2/10/2005
Radiation Safety Manual
Duke University Free Electron Laser Laboratory February 2005
2/10/2005
1. INTRODUCTION ...................................................................................................................... 3 A. BIOLOGICAL EFFECTS OF EXPOSURE TO RADIATION ............................... 3 B. PERMISSIBLE RADIATION EXPOSURES ........................................................... 4 2. RADIATION SAFETY POLICIES AND RESPONSIBILITIES................................ 6 A. THE DFELL RADIATION SAFETY COMMITTEE ........................................... 7 B. RADIATION SAFETY MANAGER (RSM)........................................................... 9 C. OPERATIONS SUPERVISOR (OS)....................................................................... 9 D. ACCELERATOR OPERATOR (AO) .................................................................. 10 E. THE EXPERIMENTER ....................................................................................... 11 F. RADIATION WORKERS. .................................................................................... 11 G. VISITORS............................................................................................................. 12 3. ADMINISTRATIVE REQUIREMENTS ......................................................................... 13 A. TRAINING ........................................................................................................... 13 B. POSTING AND LABELING REQUIREMENTS .................................................. 13 C. RADIATION SAFETY LOGBOOK ..................................................................... 15 D. RADIOACTIVE SOURCES .................................................................................. 15 E. REMOVAL OF RADIOACTIVE MATERIALS .................................................... 16 F. PERSONNEL DOSIMETERS ............................................................................... 16 4. RADIATION MONITORS .................................................................................................... 18 A. PORTABLE RADIATION SURVEY METERS .................................................... 18 B. AREA RADIATION MONITORS - ACTIVE ...................................................... 18 C. AREA RADIATION MONITORS - PASSIVE ..................................................... 18 5. ACCESS CONTROLS AND THE PERSONNEL PROTECTION SYSTEM ..... 19 A. DFELL AREA ACCESS ..................................................................................... 19 B. PPS SYSTEM ........................................................................................................ 24 C. TURN ON PROCEDURE ..................................................................................... 28 D. PPS TESTING ..................................................................................................... 30 E. RESTRICTED ACCESS MODE FOR TUNNEL, RING AND BOOSTER .......... 30 F. GAMMA MODE.................................................................................................. 31 APPENDIX A - Emergency Procedures ................................................................................. 34 APPENDIX B—Training Coursework .................................................................................... 36 APPENDIX C—Beam Permit .................................................................................................... 40 APPENDIX D—Work Permit .................................................................................................... 41
1. INTRODUCTION
The Radiation Safety Program at the Duke University Free-Electron Laser Laboratory (DFELL) has been established to protect faculty, staff, students, researchers and visitors, the general public and the environment. We have a legal and moral responsibility to operate our facilities in a safe manner in accordance with North Carolina and Federal regulations. Radiation Safety is a part of the DFELL Safety Program, and is integrated into the lab culture that safety of people is of paramount importance in all situations. This manual contains radiation safety policies and procedures that are specific to DFELL. DFELL houses four major systems of ionizing radiation: the Mark III FEL, the linac, the storage ring and the booster. In addition, ionizing radiation is produced by high-power RF sources used to drive our accelerators. Finally, ionizing radiation can be produced by components of the accelerator which may have been made radioactive by interaction with the accelerated electron beams. The ionizing radiation produced may be any or all of energetic electrons, photons (x-ray and gamma) and neutrons. A. BIOLOGICAL EFFECTS OF EXPOSURE TO RADIATION It was recognized early after the discovery of x-rays and radioactivity that exposure to ionizing radiation could have detrimental effects on biological systems The effects of radiation exposure depend upon several factors, such as the portion of the body exposed, the amount of radiation absorbed in the exposure (dose), and the rate at which the exposure was accumulated (dose rate). Some of the terms used to describe radiation and the biological effects of exposure are: • • • • • Acute – dose received in a short period of time (compared to the time required for biological recovery mechanisms to operate, generally less than 4 days) Chronic – dose received in a long period of time Somatic – exposure effects which occur in the individual receiving the dose Genetic – exposure effects which occur in the descendant(s) of the individual receiving the dose Stochastic – exposure effects which vary in probability of occurrence as a function of dose, and do not have a threshold dose below which no effects occur. • Non-stochastic – exposure effects which vary in severity as a function of dose, and have a “safe” threshold dose below which no effects occur. 3
Minimizing stochastic effects is now the main concern of radiation protection. Radiation dose limits have been established far below the dose where non-stochastic (threshold) effects would occur, even if a person were to be exposed to the dose limit over his entire working life. Limiting the stochastic effects (especially cancer induction) is achieved by keeping all justifiable exposures As Low As Reasonably Achievable (ALARA). Different dose limits have been set for various organs in the body because of varying sensitivity of tissues or organs to stochastic effects. Also, young individuals are more sensitive than adults to damage from ionizing radiation, which is especially true if an embryo or fetus is exposed in utero. For this reason, occupational exposure is more restricted (by a factor of 10) for individuals below the age of 18. Also, current regulations require that pregnant individuals restrict their occupational exposure so that a fetus does not receive more than 1/10 the yearly dose equivalent limit for workers. For more
information on the biological effects of exposure to radiation, consult the DFELL Radiation Training Manual. Radiation dose is measured and expressed in the unit rem, which accounts for both the amount of energy absorbed (measured in rads) and the effectiveness to cause biological damage (expressed by the quality factor) of the different types of radiation. The SI unit for absorbed radiation is the sievert (Sv), which is equal to 100 rem. For more information on the types of radiation, and radiation measurements and units, consult the DFELL Radiation Training Manual. Dose limits refer to measured doses from which the background radiation has been subtracted, either by use of Control dosimeters or careful radiation measurements in areas where only background radiation is present.
B. PERMISSIBLE RADIATION EXPOSURES
Unnecessary radiation exposures must be avoided.
All doses must be kept As Low As Reasonably Achievable.
The limits listed below are regulatory limits and should not be considered as being acceptable doses. The ALARA policy is the overriding guideline for setting radiation exposure. The Duke Radiation Safety Office will provide guidance on various methods to minimize 4
exposure which are suited to the particular requirements of DFELL personnel. These may include installation of additional shielding, moving or reconfiguring work areas, and limiting time spent in radiation areas. For example, during the maintenance of equipment in the linac tunnel during accelerator shutdowns, radiation from activated components of the accelerator may create dose rates that could cause a dose of 50 mrem in one month. Work in this area should be limited in duration as much as reasonably possible, or the work should be delayed until the activity has decayed to acceptable levels. The following regulatory annual exposure limits apply to trained radiation workers over the age of 18 years (from NC Regulations, 15A NCAC 11): 1. 5 rem (0.05 Sv) to the whole body 2. 15 rem to: a. the lens of eye (where major fraction of body trunk is not exposed) b.a single organ c. the skin of the whole body d.the extremities 3. 500 mrem over full gestation period of a fetus due to occupational exposure of mother
The regulatory exposure limits in uncontrolled (public) areas are: 1. 2. 100 mrem in any one year. 2 mrem in any one hour; or,
The regulatory annual exposure limits for individuals 18 years of age or under is one-tenth of the limits given above for public areas.
To provide a comparison, the average annual dose to persons living in the Durham area from background radiation is about 360 mrem (about 82% from natural sources) and a typical annual exposure from medical procedures is about 100 mrem.
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2. RADIATION SAFETY POLICIES AND RESPONSIBILITIES
The radiation safety policies and procedures set forth here are prepared specifically for the professional research staff employing the electron accelerators in DFELL. All statements relating to radiation protection comply with the requirements of the Duke University Occupational and Environmental Safety Office (OESO) - Division of Radiation Safety (hereafter, Duke Radiation Safety), Duke University Radiation Safety Committee and Radiation Safety Manual, and North Carolina Regulations for Protection Against Radiation. All persons involved with the use of the Mark III FEL, linac, storage ring and booster must have a working knowledge of these guidelines and must comply with them. Failure to comply with the procedures in this document may result in disciplinary action. The precise formulation of the radiation safety program at an experimental facility such as DFELL will change with the experimental configuration. Consequently, radiation rules and procedures will change with time. Sections of these procedures will be revised as to reflect such changes as needed. The formal statement of these rules and regulations must be approved by the DFELL Radiation Safety Committee and by Duke Radiation Safety. This Radiation Safety Manual is a part of our application for the DFELL Accelerator License, and compliance with the manual is required to maintain this License. This Manual, the License, the NC Regulations and Notices to Workers and to the Licensee are all available in the DFELL control room. The Duke Radiation Safety Office (in the Environmental Safety Building, phone - 6842194) is available to give assistance in matters relating to radiation safety from 8:30 A.M. to 5 P.M., Monday through Friday. In the event of an emergency, call 911. Emergency procedures are given in Appendix A. The following diagram shows the structure of authority for radiation safety at Duke University.
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Provost Duke Radiation Safety Committee Duke Radiation Safety Office DFELL Radiation Safety Committee FEL Lab. Radiation Safety Manager Operations Supervisor
Laboratory Staff
Operators
Visitors
Figure 1. Radiation safety authority.
A. THE DFELL RADIATION SAFETY COMMITTEE The Radiation Safety Committee assists in creating and formulating DFELL radiation safety policies. The committee has the following responsibilities: •
Updating and approving the rules and procedures contained in this document and accelerator operating modes and procedures, to reflect new information or changing conditions.
•
Reviewing and approving proposed changes in accelerator and shielding configurations that could change the radiation dose rates to personnel and the general public.
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• • •
Reviewing the operation and operational records for the lab. Reviewing unusual or abnormal occurrences or performance of workers and equipment. Approving operators capable of safely operating the accelerators.
The DFELL Radiation Safety Committee has six members: 1. The DFELL Radiation Safety Manager (chair) 2. 3. 4. The DFELL Director The DFELL Associate Director for Research The DFELL Operations Supervisor
5. An appointee of Duke Radiation Safety 6. One member from the Duke University Radiation Safety Committee
This committee will meet as needed to review radiation safety issues for the Laboratory’s accelerators, but at least four times per year. Any member of the committee can call a meeting of the committee, as well as the Duke University Radiation Safety Officer and the Chair of the Duke University Radiation Safety Committee. The committee chair will develop the agenda with assistance from other members. The quorum for a committee meeting will be three members. Situations will arise where the rules and procedures in this document may need special interpretation. When a special interpretation is needed quickly (i.e. before a meeting with the Radiation Safety Committee can give an authoritative opinion), it may be given by the DFELL Operations Supervisor, the Radiation Safety Manager, or the DFELL Director. All operations involving rule interpretations must be recorded in the Radiation Safety Logbook located in the control room, with written notification to the RSM and DFELL Director, for later consideration by the DFELL Radiation Safety Committee. The person authorizing the action must be recorded and that person must sign off on the action. It is the responsibility of the person making the interpretation or extension of the rules to bring this to the attention of the full committee, at its next meeting. In the event of a dispute, the Radiation Safety Manager or the Director of the Laboratory can give a decision. If the Radiation Safety Manager or the Director cannot resolve a dispute, the matter should be presented to the DFELL Radiation Safety Committee for a decision. The 8
ultimate authority for interpretation of radiation safety related issues resides with Duke University Radiation Safety Officer and the Duke University Radiation Safety Committee.
B. RADIATION SAFETY MANAGER (RSM) The Radiation Safety Manager, is authorized to terminate immediately any project or operation that is found to be a threat to the health of employees or members of the public, or to property and environment of the University or local community. Operational decisions made and actions taken by the local RSM are subject to full review by Duke Radiation Safety and by the Duke University Radiation Safety Committee. The RSM is responsible for: • • • Ensuring that established policies of radiation safety are followed and ensuring compliance with the State of North Carolina Accelerator License conditions. Provides local oversight of radiation control activities, including providing any material needed for the issuing of the Beam Permit by Duke Radiation Safety (see Appendix C). Halting operations if unsafe or unacceptable conditions exist. Operation may resume only when authorized by Duke Radiation Safety upon recommendation of the RSM.
The RSM’s responsibility is one of oversight. The responsibility for implementation of the rules, procedures and policies in regard to radiation safety is vested in the DFELL Operations Supervisor and carried out by all DFELL personnel. C. OPERATIONS SUPERVISOR (OS) The DFELL Operations Supervisor (OS) is responsible for the day-to-day supervision of accelerator operations and for the implementation of radiation safety procedures and policies. The OS supervises the accelerator operators and provides direction to all radiation workers and visitors to DFELL. As a member of the DFELL Radiation Safety Committee, the OS also acts as an intermediary between that committee and the experimental users of the facilities. In matters of Radiation Safety, the OS will report to the Radiation Safety Manager. If the OS will be away from the laboratory for an extended period of time, one of the members of the FEL Radiation Safety Committee will assume the responsibilities for radiation safety in day-to-day operations, with the approval of the Radiation Safety Manager.
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D. ACCELERATOR OPERATOR (AO) An Accelerator Operator is a person who has been trained as an operator, and has been approved by the DFELL Radiation Safety Committee. An AO may be given authority to operate any of the DFELL accelerators. A list of approved Accelerator Operators will be posted in the control room, with the operator’s name and which accelerator(s) the operator has been trained to operate. During normal operation of the accelerators, monitoring and enforcing radiation safety is carried out by the AO, who has the responsibility of ensuring safe operation of the accelerator. The AO reports to the OS, who will provide continuing advice on issues regarding the safe operation of the accelerator. When in doubt, the AO must consult the OS, the RSM or DFELL Director for decision authority. The AO must always choose actions which will best protect people, the equipment and the environment. Safety will always take precedence over operation of an accelerator. The most important responsibility of the operator is to ensure personnel safety, and that the Personnel Protection System (see section 5.b) is not compromised. Safe operation is partially assured through hardware interlocks. Complete safety is only ensured by AO vigilance. The operator must not permit or perform any unauthorized action that might compromise the personnel protection interlocks. The operator must insist that all experimenters follow the DFELL rules and regulations and procedures. If in the operator's opinion an experimenter is not complying with the radiation rules or if a dangerous situation arises due to excessive production of radiation, the operator must discontinue operation, and report the incident to the OS. The number of operators required in the control room will depend on the number of accelerators operating. If only one accelerator is operating, one operator is required. However, a second individual, who is a trained DFELL radiation worker, must be available in the facility to help in the event of an emergency. This individual must remain in close contact with the accelerator operator while the machine is running. If the Mark III and any other accelerator are operating, two operators must staff the control room. The operator is responsible for: • • Operation of the accelerators in a safe manner, following the requirements of the Beam Permit Terminating any unsafe operations 10
• • •
Maintaining records in the Radiation Safety logbook Performing routine checks of radiation safety monitors and interlocks Performing radiation surveys of accelerator beam lines and posting any activated areas
E. THE EXPERIMENTER The experimenter is responsible for radiation safety aspects associated with his experiment. In planning his experiment, potential radiation hazards must be studied, and wherever possible radiation levels generated during the experiment must be maintained as low as reasonably achievable, by the incorporation of shielding or other appropriate methods. In cases where access to accelerator components is required, a Work Permit (see appendix D) regarding radiation safety is to be submitted through the OS to the DFELL Radiation Safety Manager for approval. Particular care must be exercised if it is proposed to change the configuration of an accelerator system. Advice and assistance in planning may be obtained from the OS, the RSM, and from members of the DFELL Radiation Safety Committee. In the event of unusual operational conditions, the experimenter must consult with the OS. The DFELL Radiation Safety Committee must approve experiments that will involve modification of radiation shielding, new accelerator beamlines, or that have the potential of producing a large quantity of activated components. Detailed plans for such experiments will be submitted to the OS for approval and then, if accepted at that stage, be forwarded to the RSM for communication to the DFELL Radiation Safety Committee for consideration. Experimenters and all collaborators, coworkers and visitors in an experiment must fulfill all of the responsibilities of Radiation Workers, given below. F. RADIATION WORKERS. Authorized radiation workers are responsible for following all applicable regulations in this document and the Duke University Radiation Safety Manual. An authorized radiation worker is a person who has satisfied the radiation safety training requirements for unescorted access to the Controlled Areas of the DFELL (see Training in Appendix B). An authorized radiation worker need not necessarily be a Duke University Employee. Radiation workers must carry out the following responsibilities: • Understand and implement the appropriate radiation safety policies and procedures for DFELL. • Conduct operations so as to minimize exposure (internal and external) to all personnel in the laboratory.
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•
Wear a personnel monitor as directed in Section 3.f. (Dosimeter Badges) and make the monitor available for scheduled exchanges.
G. VISITORS Persons who are not authorized DFELL radiation workers are considered to be visitors and are not allowed to enter the Controlled Areas without an escort. Only authorized DFELL radiation workers may act as visitor escorts. Escorted visitors: • All visitors must be advised that they are entering a controlled area. The visitor must be instructed that they are authorized to go to only specific locations within the lab, and that there are specific locations where they may not enter without an escort. • • A pocket dosimeter must be given to each visitor (to each individual, or one per group if the group will remain together). All visitors must be logged in the logbook at ring room main entry. On entry, log the name of visitor or all members of a group, time of entry, dosimeter number and reading, and name of escort. On exit, log time of exit and dosimeter reading. • If a visitor will be unescorted in the controlled area at any time, they must receive a Visitor Instruction Sheet, listing these requirements. The specific locations in the lab where the visitor is expected to be present must be written on the sheet, and the sheet must be signed by the visitor and by the escort. The sheet will be placed in the Visitor Instruction box, for recording and archiving. • All visitors to the controlled areas must be under the supervision of a trained radiation worker. Most visitors are expected to be escorted at all times in the controlled areas, and must be admitted to these areas only by a trained radiation worker. Visitors who require unsupervised access must be trained as radiation workers, i.e. receive orientation materials, pass the Radiation Safety Quiz, and be issued a dosimeter badge.
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3. ADMINISTRATIVE REQUIREMENTS
Certain administrative procedures are required to protect laboratory personnel, to comply with North Carolina State radiation safety guidelines and the requirements of the DFELL Accelerator License, and to control radiation exposures. These include training, proper posting of radiation sources, keeping proper records of the performance of the personnel protection system and radiation survey meters, establishing emergency procedures, and handling radioactive sources. These procedures are detailed in this section. The following official records must be kept: • • • • Radiation Safety logbook Visitor log and sign out log for temporary pocket dosimeters, and visitor’s TLD badges. Record of training of operators and radiation workers Beam Permit
A. TRAINING All DFELL radiation workers (including experimenters and research visitors) who require unescorted access for work in the controlled area must have a working knowledge of the radiation rules and procedures and be familiar with the facility. Each worker must read the DFELL Radiation Safety Manual, DFELL Radiation Training Manual and Duke University Radiation Safety Manual, and successfully pass the DFELL Radiation Safety Quiz. DFELL staff and other Duke University employees must also participate in update training, either a safety presentation or using the online update training provided by Duke OESO. New members of DFELL staff will also receive an orientation from their supervisor explaining hazards, procedures and policies at DFELL. An outline of the topics covered in Radiation Safety Training can be found in Appendix B. Accelerator operators will receive more complete training (see Appendix B). This will acquaint the operator with a general knowledge of the effects of radiation, dose reduction techniques, accelerator operating procedures, the personnel protection system, and administrative safeguards.
B. POSTING AND LABELING REQUIREMENTS
The following is a description of the types of radiation warning signs which may be found at DFELL.
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1.
A "CAUTION CONTROLLED AREA" sign to identify an area where radiation dose must remain below 5 mrem per hour. A controlled area is a restricted access area, and acts as a buffer between public areas and areas where higher levels of radiation may be present. “Controlled Area” warning signs are posted at all entries into the ring room.
2.
A "CAUTION RADIATION AREA" sign to identify an area where a person could receive a whole body dose in excess of 5 mrem in any one hour.
3.
A "CAUTION HIGH RADIATION AREA" sign to identify an area where a person could receive a whole body dose greater than 100 mrem per hour. Access to such areas is by interlocked entries.
4.
5.
A "VERY HIGH RADIATION AREA - GRAVE DANGER" sign to identify an area where a person could receive a whole body dose greater than 500 rem per hour. Entry to such areas is by redundantly interlocked entries. Breaking any interlock will prevent radiation producing operations, such as injection. The tunnel, the interior of the ring shielding and the interior of the booster are the only such areas in DFELL. A "CAUTION RADIOACTIVE MATERIAL" sign to identify a spot along the beam line where induced radioactivity has been measured using a radiation survey meter. This sign must include specific information describing the level of measured radioactivity, including the observer’s name, date and time, distance at which the radiation was measured, and dose rate (mrem/hour). This sign should also be used on any radioactive items removed from the accelerator tunnel and on any radioactive sources used by DFELL personnel. A “PUSH RED BUTTON IN CASE OF RADIATION
6.
EMERGENCY/Notify Radiation Safety (911) in case of suspected overexposure” sign in the control room refers to the large red panic button mounted on the personnel protection (PPS – see section 5.B) panels. Pressing one of these panic buttons breaks the PPS panic button interlock, and prevents the production of microwave power in the accelerator sections of the Mark III and the linac.
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C. RADIATION SAFETY LOGBOOK
The DFELL must keep a radiation logbook in the accelerator control room. The AO is responsible for entering information and maintaining the radiation logbook. This log should include the following information: 1. Radiation levels measured during operations if above background. 2. Radiation levels measured during tunnel entry or restricted access to the tunnel, ring or booster, if above background level. This should include locations, dose rate, and the source of any abnormal readings. Entries must be made when dose rates are >100 mrem/hr (High Radiation Area), or when visitors enter areas with dose rates above 0.5 mrem/hr. 3. Radiation Alarms. If any of the controlled area (not Very High Radiation Areas such as the tunnel) area radiation monitor alarms activates, the time of the fault, the level of the radiation and the reason for the excess radiation should be entered in the log. 4. Investigations of unusual exposures to personnel. 5. Failures in the personnel protection system and corrective measures. 6. The results of measurements on components removed from the accelerators and the destination of the components. 7. The override of any interlock or protective system. Circumstances may arise where it is necessary to override an element of the personnel protection system on a temporary basis. Overriding of an interlock must be authorized by the Operations Supervisor or the Radiation Safety Manager. The operator must list in the radiation logbook the reasons for the override, the name of the individual who authorized the override, and methods of assuring personnel safety. The person authorizing the override must notify all of the following: Operations Supervisor, Radiation Safety Manager, DFELL Director, and Duke Radiation Safety. An acknowledgement signature is required from each next shift operator who receives the machine with personnel protection system compromised. To ensure that next shift operators note that the personnel protection system is compromised, a tag stating the change must be attached to the personnel protection panel in clear sight of the operator console. 8. A record of operations in abnormal conditions. 9. Loss of, or damage to, interlock keys and corrective actions taken.
D. RADIOACTIVE SOURCES
Radioactive sources may be used to check or calibrate radiation monitors or experimental equipment. These sources must be used according to the Procedures Guide prepared by Duke
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Radiation Safety for each source, and are also subject to posting and labeling requirements as specified in the North Carolina Regulations for Protection against Radiation. Anyone planning to use radioactive sources at DFELL must first inform the RSM. The RSM will consult with Duke Radiation Safety to ensure the appropriate procedures are in place for safe use of the source, and that the source is permitted onto the campus under the Duke University Radioactive Materials License. All radioactive sources must be shipped to Duke Radiation Safety, who then deliver the material to the Authorized User. For more details, see the Duke Radiation Safety web site.
E. REMOVAL OF RADIOACTIVE MATERIALS
Equipment or material exposed to the high-energy electron beams of all DFELL accelerators may become radioactive. Such equipment includes vacuum pipes and components, vacuum flanges, gaskets, vacuum pumps, magnets (injection and bending), beam dumps, and accelerator cavities. No item may be removed from any operational accelerator beamline without being surveyed for radioactivation and appropriately tagged if necessary. Any accelerator beamline component which will be cut, drilled or machined must be surveyed and wipe tested for radioactivity. There is also the potential for activation of surface particles and dust, which could contaminate the skin and clothing of workers as well as their tools and equipment. Before any operations involving the removal of accelerator beamline components is begun, Duke Radiation Safety must be contacted so that monitoring and tagging can be performed. Duke Radiation Safety will arrange for the disposal of unwanted radioactive material. It is illegal to discard radioactive materials in the regular trash receptacles. In the event of an accelerator being decommissioned, the Operations Supervisor must prepare a decommissioning plan. The plan must be forwarded to the DFELL Radiation Safety Committee for approval. If approved by the DFELL Radiation Safety Committee, the decommissioning plan must receive final approval from the Duke University Radiation Safety Committee. Decommissioning will also require a change or cancellation of an accelerator license and approval by NC DENR - Division of Radiation Protection.
F. PERSONNEL DOSIMETERS
All laboratory personnel who require unescorted access to the controlled areas are issued dosimeter badges. Dosimeters for new personnel are requested by completing a Personnel Dosimeter Request form and submitting this along with the DFELL Radiation Safety Quiz. Dosimeter badges must be worn at all times in the controlled areas. Visitors to the laboratory must be issued badges or pocket dosimeters if they will enter controlled areas. These are available at the west hall entrance to the ring room. 16
Duke Radiation Safety is responsible for examining dosimeter reports and for investigating any exposures exceeding the Duke University ALARA Policy Investigational Levels. All such exposures are discussed with the personnel involved so that future exposures are reduced. The pocket dosimeters are calibrated annually by Duke Radiation Safety. The dosimeter reports are reviewed by the DFELL Radiation Safety Committee. Duke Radiation Safety receives and sends requests for individuals' occupational exposure records. Exposure records are confidential and a Release Form (available from Duke Radiation Safety) must be obtained from the requester and must be included in outgoing requests to other institutions. Any lose of a dosimeter badge must be reported immediately to the Operations Supervisor. The badge owner must make a written report to the OS indicating the circumstances surrounding the loss of the dosimeter, as well as a Certification of Lost Badge for Duke Radiation Safety. The OS will report the loss to the RSM and Duke Radiation Safety. If a badge is found which may have been lost, report this immediately to the Operations Supervisor, including the name on the badge, and the time and place of the discovery. The OS will report the badge to Duke Radiation Safety. Failure to promptly respond to this situation, especially when the badge is found in a radiation area, may severely impair the efforts to assess the badge wearer's actual exposure.
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4. RADIATION MONITORS
A variety of radiation detectors are used at DFELL to monitor the performance of the shielding and personnel protection system. These detectors are described below. A. PORTABLE RADIATION SURVEY METERS Portable ionization chamber radiation survey meters are used to monitor gamma radiation levels, and moderated proportional gas tube survey meters for neutron radiation levels. DFELL personnel must use a survey meter whenever entering any area where the possibility of a high radiation level exists. Geiger counters and all other pulse counting radiation monitors should not be used when the accelerators are operating because they can show false radiation levels due to pulse pile-up. Only ionization chamber meters should be used with an accelerator running. There are ionization chamber survey meters (such as Victoreen model 450P) available in the control room. These meters are checked for operation on a monthly schedule by the DFELL accelerator operators, and calibrated annually by Duke Radiation Safety. B. AREA RADIATION MONITORS - ACTIVE Area radiation monitors are in use at various locations in the lab to provide real-time measurement of dose rates, and in some cases to provide active interlock switch closures due to high radiation levels for the personnel protection system. These alarms are tested for operation and alarm activation during testing of the personnel protection system, and a complete list of the area monitors is contained in the test procedure. If an area radiation monitor alarm activates, personnel in the area should contact the accelerator operator about the excess radiation level indicated by the monitor. The cause of the alarm will be investigated and noted in the Radiation Safety Logbook by the AO. C. AREA RADIATION MONITORS - PASSIVE Duke Radiation Safety monitors radiation levels at various locations in and around the DFELL accelerators, using integrating passive detectors (called area dosimeters inside the controlled areas, to monitor dose to radiation workers, and environmental dosimeters outside the controlled areas to monitor dose to the public). These must not be moved or tampered with. The environmental dosimeter reports are reviewed by the DFELL Radiation Safety Committee. 18
5. ACCESS CONTROLS AND THE PERSONNEL PROTECTION SYSTEM
The primary hazard from ionizing radiation at DFELL arises from accelerated electrons, which create radiation when striking atoms in a solid, liquid or gas, and from the prompt x-ray and gamma-ray bursts generated by the accelerators and high voltage equipment. A secondary hazard arises from residual activation of beamline components following operations. The Personnel Protection System (PPS) is a hardware system designed to protect personnel from hazards associated with ionizing radiation present during accelerator operation. This
system must be maintained with utmost care since its proper functioning is essential to ensure the safety of laboratory personnel. When the DFELL accelerator systems are not being operated, there may be other sources of radiation, including induced radioactivity of accelerator and beam transport components, target assemblies and beam dumps, radioactive components removed from the accelerator, radioactive sources used for calibration or other purposes, and x-rays emitted by high voltage systems (e.g. klystrons, RF cavities). Personnel may not be protected from these sources by the PPS system. All radioactive sources, source storage areas, radioactive components, and areas of high radiation must be clearly marked. It is the duty of all workers to observe and comply with the restrictions listed on these signs.
A. DFELL AREA ACCESS Shown below are diagrams of the DFELL tunnel and the ring room areas. Because of the ongoing upgrades and associated reconfigurations, certain items may not be located exactly where indicated on these diagrams.
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20
Fenced Area North of Ring Room Gate
DFELL Phase 2
Ring Room
d
p 7
p 8 p 3 p 4 p p 5
p p
p 9
s
Linac / Mark III Tunnel
p 2
p
p 1
p
p 6
s s
a d f
Ring Shielding
Keck Building 1st Floor
d
DFELL Offices
p 11
s
d d p 9 f
s
p p p 8 p
s
p p 10
DFELL Phase 3
p 3
p p 4
s
p 6 p p 5
p 2
p
p 1
p p p 7
s
a d
f
s
d
Note: drawing not to scale
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Uncontrolled Areas: These are areas in which the yearly dose does not exceed 100 mrem and the dose rate does not exceed 2 mrem/hr. ALARA goal dose rates are a factor of ten below this. Outside of the DFELL building and the office areas in the FEL lab are uncontrolled areas. No active monitors are needed in these areas. Environmental dosimeter monitoring is performed to demonstrate that the dose rates do not exceed permissible dose limits, and to help with improvements in shielding and operations to achieve ALARA goals. Controlled Areas: This is the lowest level of limited access area at DFELL, one with a potential for dose levels up to 5 mrem/hr. Our ALARA goal is to keep radiation dose rates below 1 mR/hr in all Controlled Areas of the laboratory. Access to these areas is controlled by locked doors or gates, which are not interlocked, i.e. authorized personnel may come and go through these access points while the accelerators are operating. These doors or gates must not be left open and unattended at any time. Radiation warning signs are posted warning that radiation may be present. Radiation monitoring TLD badges must be worn in the Controlled Radiation Area at all times. Radiation Areas (5-100 mrem/hr) and High Radiation Areas (>100 mrem/hr): Such areas may exist from time to time at DFELL. Posting and safety procedures are implemented as necessary. Very High Radiation Area: This is an area where a dose rate of 500 rem/hr or greater is possible. This category includes the interior of the linac tunnel when the Mark III or linac is operating, and the interior of the storage ring shielding during beam injection. These areas have several levels of interlocks, described below. The following table shows the status of various areas in DFELL under different operating modes.
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Zone In Ring room, outside Ring shielding In Keck building, First floor In Ring room, Inside Ring shielding In Ring room, Inside Booster shielding In Linac / Mark III Tunnel Outside Ring Room, In fenced area above Tunnel Outside Ring Room, In fenced area north of Ring room Outside Ring Room, On roof of Ring room In DFELL office area and Conference room 2nd floor storage mezzanine Booster vault roof, north side
No Operations Controlled Area ** Controlled Area Controlled Area Controlled Area Controlled Area
Uncontrolled Area (public) Uncontrolled Area (public) Uncontrolled Area (public) Uncontrolled Area (public)
Mark III Operation Controlled Area Controlled Area Controlled Area Controlled Area Very High Radiation Area Controlled Area
Uncontrolled Area (public) Uncontrolled Area (public) Uncontrolled Area (public)
Linac Operation Controlled Area Controlled Area Very High Radiation Area Very High Radiation Area Very High Radiation Area Controlled Area
Uncontrolled Area (public)
Booster Operation * Controlled Area Controlled Area Very High Radiation Area Very High Radiation Area Very High Radiation Area Controlled Area
Uncontrolled Area (public)
Controlled Area
Uncontrolled Area (public)
Controlled Area
Uncontrolled Area (public)
Controlled Area Very High Radiation Area Booster vault roof, Controlled Controlled Very High Very High Radiation Radiation south side Area Area Area Area * - Access restrictions during Booster operation will be verified during booster commissioning by radiation surveys ** - During extended shutdowns, certain areas may be made Uncontrolled Areas on a temporary basis following radiation surveys Following the termination of an operational run, the tunnel will make a transition from very-high radiation area to controlled area. Before the tunnel is opened for general access by
Controlled Area Controlled Area
Controlled Area Controlled Area
Controlled Area Controlled Area
radiation workers by breaking the tunnel search PPS interlock, the AO will be responsible for carrying out a radiation survey around electron guns and sources, beam dumps, energy 23
spectrometers, magnets and known aperture restrictions, checking for possible radiation sources and activated components. In areas where doses from residual activation exceed 1 mrem/hr at a distance of 3 feet from the source, a warning sign (see section 3.B) must be posted before allowing anyone else to enter the tunnel. The opening of the accelerator for worker access, and posting of warning signs must be entered in the Radiation Safety Logbook. If the search has not been broken, and another radiation worker requires access to the tunnel, they will enter with AO permission using the restricted access mode, and carry a portable survey meter (see section 5.E), or else the AO must perform the required survey and break the tunnel search. If an accelerator has not been in operation since the previous survey recorded in the Radiation Safety Logbook, the survey is not required before worker access is allowed.
B. PPS SYSTEM The personnel protection system is a hard-wired relay logic system. While computers may be used to monitor the status of elements of the PPS system, there is no active computercontrolled component in the PPS system. The core of the PPS system is a set of hardware boxes in the control room. These boxes accept signals from the various PPS indicators such as door switches, search indicators, or the keybanks, and use them to activate the actuators of the systems such as warning lights, klaxons, and the switches to enable or disable accelerator operation. Each PPS signal controls a latching failsafe interlock relay and an indicating LED for status. There is a reset button that resets all interlock relays in a PPS box. The interlock relays are connected in series so that if any one relay is de-energized, the accelerator system is disabled. If the entire series of relays is energized, a relay which supplies power to the actuators will close. The power relays, the power supplies for the interlock relays as well as the LEDs are all mounted in boxes next to the door of the south ring stairs entry and next to the tunnel entry. When the entire PPS system for an accelerator is energized, a final signal called the “PPS grant” is active, and the accelerator controlled by the PPS can be operated. The PPS system is designed such that any failure state is latched. For example, if someone enters through a door the interlock relay for that door will de-energize. The door must be closed again before the PPS system can be reset. The system will also not reset until a search is carried out since the opening of the door will break the search loop. Also any PPS buttons or switches inside of an accelerator area can only be reset by entering and then making a new search. If any 24
interlock opens, it is mandatory that the reason be found and the problem be corrected before the machine is restarted. Interlocks The DFELL accelerator PPS have many interlocks which are similar (listed first), and several which are special to each accelerator. The common interlocks include: 1. Entries and Entry Switches: All entries into the tunnel, ring and booster have doors locked from the outside (which can be opened from the inside without a key) with multiple switches with closed contacts when the door is closed. Each of two redundant door switches provide input for an interlock relay. The door (and therefore switch) must be closed for each interlock relay to remain energized after being reset. If the door is opened, the interlock relay will de-energize. 2. Search System: The third switch on each entry door is part of the search system for each accelerator. A thorough search of each accelerator area must be made before the accelerator can be started. The search procedure assumes that there may be someone in the area who may be unconscious and hidden. A series of pushbuttons are used to ensure that the search has been carried out prior to startup. The search system consists of a loop of relays in boxes and a control box at the door. Each box contains a relay, a pushbutton and multicolor LED. The search boxes are wired in series, and each relay in the chain derives its power from the previous relay so that the relays must be reset in the correct order. All LEDs start out red before the search. When the search is started the LED on the first box turns yellow. When the search button is pressed, this LED turns green and the LED on the next box turns yellow. The power for the entire loop comes through the entry door search switches, so the entire search is cancelled if a door is opened during a search. Once the search is completed, a push button at the exit door will give the searcher a short interval to leave the tunnel and close the exit door. A buzzer sounds when the search interlock is bypassed. The search process will have a time limit of up to 10 minutes. If the search is not finished within this time period, the system will reset and the search must be restarted. 3. Entry Keys: The tunnel and the ring/booster/gamma vault each have a set of matched keys which open the respective entry doors to each accelerator. All door entry keys must be locked into a keybank at the control room PPS panels for the interlock to be made up. Removal of any key disables the accelerator. There are no spares for these keys. If a key is lost, the entire key bank must be re-keyed before operations can resume, to prevent the use of an unauthorized duplicate key. If a key is damaged, a replacement key may be made by having the damaged key destroyed at the Duke University Key/Lock Shop, the
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replacement key authorized by the DFELL Key Controller, and the destruction of the damaged key certified by the RSM in the Radiation Safety Logbook. 4. Panic Buttons: There is a set of panic buttons that can be used to disable the accelerator in an emergency. The panic buttons are mounted in the search boxes and in other boxes inside of the tunnel, ring, booster and gamma vault, and on each control room PPS box. Pressing any panic button will immediately disable the accelerator. 5. Visual and Audible Warnings: Visual and audible warnings are given to personnel in and around the tunnel or the interior of the ring room shielding when the search is complete and the PPS reset button is pressed, before the accelerator operation starts. There is a rotating red light at the entrance of the tunnel, ring and booster indicating that the accelerator is prepared for operation (i.e., all interlocks made up and PPS grant is energized). There is a klaxon inside the tunnel and at the entry to the ring which sounds for 15 seconds after the PPS reset button is pressed. There is a two-minute delay after the PPS reset is pressed before the PPS grant is energized. This two minute delay is necessary in order to give a person inside the tunnel, ring or booster time to disable the accelerator or to leave the tunnel/ring/booster. The PPS grant signals are derived from the power for these warning devices so that the accelerator cannot operate without applied power. Special Tunnel Interlocks 1. Emergency Exit Hatch: This is located at the east end of the linac tunnel and can only be opened from the inside. It has two door switches wired to interlock relays. 2. Tunnel Blocks: These removable blocks close off the west end of the tunnel, and there is a switch to sense that the top block is in place which is wired to an interlock relay. 3. Tunnel Pull Rope: This is mounted between the Mark III and the linac. Pulling the rope opens the switch at the west end which is wired to an interlock relay. 4. Tunnel Radiation Monitors: Two interlocked area radiation monitors are wired to interlock relays, one located above the tunnel on the berm inside the fenced area, and one in the control room under the tunnel PPS box. There are also non-
interlocked radiation monitors with detectors in the tunnel and displays in the control room.
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Special Ring Interlocks: 1. Stacked Block Shielding: The primary radiation hazard in the storage ring room is from beam that is lost during injection from the linac into the ring. A concrete shielding wall (2 feet thick and 8 feet high) surrounds the storage ring and linac to ring beam transport section. Some parts of the wall, adjacent to the mezzanine floor, are 12 feet high. The concrete wall consists of interlocking pre-cast blocks. The integrity of these blocks is required by the Beam Permit, and these must be inspected before commissioning after an extended shutdown, and must only be removed under an approved Work Permit. High Energy Spectrometer (HES): When energized, the HES magnet in the tunnel directs the beam from the linac into a beam dump. The HES magnetically sensitive switch is wired to an interlock relay. The HES magnetic field must be above the limit set by the switch location to energize the relay. There are two modes of HES permit: Startup mode: A HES interlock is closed when the HES is energized above threshold. In this mode the electron beam is directed to the beam dump and injection into the ring is not possible. Injection mode: To allow injection of beam from the linac into the ring, the HES PPS bypass key must be activated. This key must be stored in the interlock key safe when not in use, and is to be inserted only by an accelerator operator. Ring Permanent Magnet: This magnet is located inside the ring shielding on the beginning of the gamma beam pipe. The magnet will deflect any electrons which might go straight out of the south straight section of the ring (say, due to a fault in the first bending magnet) into the floor of the ring, inside of the ring shielding. The permanent magnet magnetically sensitive switch is wired to an interlock relay, and the switch is closed only if the magnet and switch remain in close proximity. Tunnel PPS Grant: The tunnel PPS must be completed and the tunnel PPS grant energized before the ring PPS can be completed. The tunnel PPS grant is wired to an interlock relay. Operating Mode Dependant Interlocks: Several signals are developed in the Gamma PPS box and interact with the ring PPS box. If the ring is operating in Gamma mode, and any of the interlocked area radiation monitors mounted along the gamma beam pipe reaches a high alarm state, the switch wired to the Gamma BL Rad Monitor interlock relay in the ring PPS box will open (disabling the linac), and the southeast periscope will insert into the beam line (preventing operation of the FEL). If the ring is operating in gamma mode, and any of three ring interlock relays (ring keybank, ring search, ring panic buttons) deenergize, the SE periscope will insert into the beam line. If the ring is operating in
2.
3.
4.
5.
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normal mode, and the southeast interlocked radiation monitor reaches a high alarm state, the SE periscope will insert into the beam line.
Special Booster Interlocks: 1. Stacked Block Shielding: The booster vault is primarily a poured concrete structure with 2 foot thick walls and a 1 foot thick roof. The two large entries to the booster are closed with interlocking pre-cast concrete blocks. The integrity of these blocks is required by the Beam Permit, must be inspected before commissioning after an extended shutdown, and must only be removed under an approved Work Permit. 2. Tunnel PPS Grant: The tunnel PPS must be completed and the tunnel PPS grant energized before the booster PPS can be completed. The tunnel PPS grant is wired to an interlock relay.
C. TURN ON PROCEDURE The proper turn-on procedure for the Mark III FEL, linac, storage ring and booster consists of the following steps: 1. The tunnel PPS search is enabled with the tunnel search key using a switch in the box mounted at the tunnel entrance. This provides power to the PPS search. 2. The operator initiates the search and enters the tunnel. The door must be closed during the search. The operator should check that all the removable blocks in the maze and local shielding bricks are in place during the search. 3. The operator searches the tunnel, pressing each search button in sequence. Any personnel who are found during the search must report to the exit door but must not leave the tunnel until the operator completes the search and exits the tunnel. 4. The operator activates a temporary override of the door interlock to exit the tunnel. 5. All entry keys must be inserted into the tunnel keybank and the keybank must be locked. At this point the tunnel personnel protection loop should be satisfied and all relay monitors should indicate yellow. Pressing reset will turn all LEDs green and start the delay relays for enabling the Mark III FEL. A yellow light on the tunnel PPS panel will
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light. The rotating red lights are energized and the klaxon inside the tunnel sounds for 15 seconds. 6. When the two-minute delay is finished the tunnel PPS grant is active, and a green beam permit light should light on the tunnel PPS panel. With this level of PPS grant, it is possible to operate the Mark III FEL only. 7. The booster PPS search is enabled with the booster search key using a switch in the box mounted near the search entry. 8. The operator initiates the search and enters the booster. All entries must be closed during the search. 9. The operator searches the booster, pressing the search buttons in sequence. Any
personnel who are found during the search must report to the exit door but must not leave the booster until the operator completes the search and exits the booster. 10. The operator activates a temporary override of the search interlock to exit the booster. 11. All entry keys must be inserted into the ring keybank and the keybank must be locked. At this point the booster PPS loop should be satisfied and pressing the system reset, should turn all LEDs green and start the delay relays for enabling the linac and the booster. A yellow light on the booster PPS panel will light. The rotating red lights are energized and the klaxon on the booster wall sounds for 15 seconds. 12. When the two-minute delay is finished, the booster PPS grant is energized and a green permit light on the ring PPS panel should light. 13. The ring PPS search is enabled with the ring search key using a switch in the box mounted near the search entry. 14. The operator initiates the search and enters the ring. All entries must be closed during the search. 15. The operator searches the ring, pressing the search buttons in sequence. Any personnel who are found during the search must report to the exit door but must not leave the ring until the operator completes the search and exits the ring. 16. The operator activates a temporary override of the search interlock to exit the ring. 17. All entry keys must be inserted into the ring keybank and the keybank must be locked. At this point the ring PPS loop should be satisfied and pressing the system reset, should turn all LEDs green and start the delay relays for enabling the linac and the storage ring. A
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yellow light on the ring PPS panel will light. The rotating red lights are energized and the klaxon on the ring wall sounds for 15 seconds. 18. When the two-minute delay is finished, the ring PPS grant is energized and a green permit light on the ring PPS panel should light.
D. PPS TESTING The personnel protection system is tested to ensure the operation of each interlock and to ensure that the PPS grant is not energized if any one interlock is not satisfied. This test is performed prior to and as a requirement of completing and issuing a new Beam Permit. During extended shutdowns for upgrades or repairs, issuing of a new Beam Permit is delayed, and therefore PPS testing. However, any accelerator which remains active must have the PPS tests performed at least every 6 months. The PPS test is performed by at least two workers. They will follow the PPS Test
Procedure available in the control room, which is kept updated to include every interlock in each PPS system. PPS testing must demonstrate 100% functioning of all interlocks – any failed interlock must be repaired or replaced before the PPS test can be considered complete. The Operations Supervisor will be responsible for assigning personnel to test the PPS system. A least one member of the test team will be an Accelerator Operator.
E. RESTRICTED ACCESS MODE FOR TUNNEL, RING AND BOOSTER
After the search is completed for the tunnel, booster or ring, it is possible to go into a restricted access mode for intermittent brief access to these areas under carefully controlled conditions. After searching the tunnel, booster or ring, these become restricted areas. During a restricted access, the search status is not broken, so no search needs to be redone, unless there is a violation of the restricted access rules. A video camera is mounted at the entrance to the tunnel, the ring and the booster to assist the operator in verifying from the control room that no person enters the restricted area who does not have a key from the appropriate keybank. The accelerator operator has control over granting access to restricted areas. It is the responsibility of the operator to:
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•
Ensure that the current operational state of the accelerator in the restricted area is safe for entry of personnel, and that restricted access entry complies with any requirements of the Beam Permit.
• • • • •
Issue an entry key to each individual who enters a restricted area. Log the time of entry and names of the individuals who enter the restricted area. Activate the bypass button on the PPS panel in the control room. Secure all entry keys from each person when they exit the restricted area. Be on duty in the control room at all times during a restricted access-mode entry.
Each person wishing to enter a restricted area must coordinate with the operator, and is responsible to: • Receive an entry key and keep it with them at all times during the restricted access (one person = one key). Having a key ensures that the keybank interlock is off, and the accelerator is disabled. • • • • Observe any caution signs in the restricted area, and any warnings of operating equipment given by the operator. Use an operating radiation survey meter, to ensure that no one will enter an area with a radiation dose over 5 mrem per hour (one survey meter per group). Press the search bypass button near the entry door before opening the door. Return the entry key to the operator when access is completed.
It is important that only the search interlocks can be bypassed in this procedure. The door interlocks, the keybank interlocks, the panic buttons, pull rope and all other interlocks are all still active during this procedure. It is also important that permission to enter a restricted area must be from the operator in charge. Thus, two people must be present for this procedure to work: one who enters the restricted areas, and one who activates the restricted access button in the control room.
F. GAMMA MODE The lower floor of the Keck building is dedicated to beam lines emerging from the south east corner of the ring shielding. The gamma beam line is aligned with the ring south straight section. It provides an unbroken vacuum path for transporting gamma rays to the inside of the 31
Gamma Vault. The beam pipe consists of 4” stainless steel tube with no radiation shielding. As this passes through an occupied area, it is essential that the beam pipe remain clear of all obstructions that could scatter the gamma beam during gamma operation. To ensure this, all valves and periscopes are fitted with position switches. The switches provide inputs to the Gamma PPS box. The gamma PPS disables gamma production by inserting the upstream
periscope to interrupt the optical cavity and thereby inhibit operation of the laser unless all downstream valves and periscopes are out. Area radiation monitors are positioned along the gamma beam pipe to monitor radiation levels, and these are also interlocked in the gamma PPS. The gamma PPS box has LED indicators to show the status of the interlocked devices. A lit LED signifies that the switch is closed and the interlock relay is energized. There are indicator lamps and buttons having the same functions as the corresponding controls on the tunnel and ring PPS boxes. One special interlock on the gamma PPS is the vacuum ion pump controller for each pump has a window detector to ensure that the measured pressure is in the correct range. The vacuum pump controllers have a switch wired to an interlock relay in the gamma PPS box. The periscope key must be used to initiate the search of the gamma vault, and this key can only be removed in the “In” position, thus ensuring that no laser operation can occur while the gamma vault and collimator shack searches are in progress. When the gamma vault and
collimator shack searches are completed and all other interlocks are energized, pressing the reset button will initiate the warning delay sequence. After the warning delay, the gamma beam permit light will be on and a yellow sign will flash in the control room and at the gamma vault. The gamma PPS grant requires: ! ! ! All interlock switches are closed, including the search, all insertable device position switches and the beamline vacuum controller pressure interlock switches. The reset button is pressed. A start up delay of completes.
The upstream periscope position is first controlled by the periscope key. If the key is in the “In” position, the periscope will be inserted at all times. The second control of the periscope position depends on the position of the gamma key, which can be in “Gamma” or “Normal” mode. In the normal mode, the southeast Optics area radiation monitor interlock must be energized as well as the chain of gamma beam pipe area radiation monitors. For any high alarm state, these radiation monitor interlocks open and cause
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the upstream periscope to be inserted. The relay may be reset when the radiation dose rate falls below 5 mrem/hour, and the reset button pressed. In the gamma mode, following conditions must be true: • • • • • The gamma PPS grant is available. The startup delay has completed. The chain of gamma beam pipe area radiation monitor interlocks is closed. Three ring interlock relays are energized – ring keybank, ring search and ring panic buttons. The periscope keyswitch is in the “Out” position.
It is then possible to remove the upstream periscope using the EPICS controls.
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APPENDIX A - Emergency Procedures
EMERGENCY PROCEDURES FOR RADIOACTIVE MATERIAL SPILLS OR CONTAMINATION
In Case of Emergency, Always Call for Help: Duke Police, 911 1) Notify Emergency Responders and Lab Personnel Treat every spill as if radioactive contamination has occurred, until it is demonstrated by Emergency Responders that contamination has not occurred. • • • Notify other persons in the area of the spill. Notify the Radiation Safety Division. (see contact numbers below) Notify the DFELL Radiation Safety Manager, the DFELL Operations Manager, and the DFELL Director. (see contact numbers below)
For serious incidents and injuries - call the emergency number (911) to arrange transport to the Emergency Department. Tell them this is an accident involving radioactive materials. Communicate with the accelerator operator so that accelerator operation can be halted, until emergency responders have completed their work and left DFELL
2) In the Spill Area Mark the spill area and limit access to avoid the inadvertent spread of contamination. Any person who enters the spill area should remain in the vicinity until any needed decontamination can be completed. Keep a written list of all people who enter the area of the spill. Evacuate if the spill is of a volatile material.
34
Immediately remove contaminated shoes or clothing. Write down as much detail as possible about how the spill occurred. Let the Emergency Responders, who have extensive training, direct the isolating and cleanup of any spill.
3) In Case of Fire If the spill involves a fire, evacuate the area and pull the Fire Alarm on the way out of the building. Duke University Police will notify the Radiation Safety Division. Close any windows and doors that can be reached safely. As quickly as possible, shut down all operating accelerators and high voltage power supplies in the area. Primary Contacts in Radiation Safety Division of Duke OESO Phone Vashek Vylet (accelerators) Greta Toncheva (accelerators) Greg Egan (sealed sources) David Jorgensen (operation mgr) 668-3189 668-3187 668-3158 668-3183 Pager 970-1224 970-7798 970-8754 970-3619
Contacts in FEL Laboratory Phone Pat Wallace (Rad Safety Manager) Ping Wang (Operations Manager) Glenn Edwards (Lab Director) 660-2661 660-2669 660-2674
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APPENDIX B—Training Coursework
This section gives a synopsis of the training course for radiation workers and operators of accelerators at DFELL. Some of the training material may be given to the trainees in written form. Written material will include the DFELL Radiation Safety Manual, and the Duke University Radiation Safety Manual. Radiation Workers The following topics will be covered in the user orientation and facility tour. 1.) Definition of terms a.) Roentgen b.) Rad c.) Rem, Gray d.) Curie, Bequerel e.) Conversion equations Dose limits a.) Radiation workers b.) Non-radiation workers The ALARA concept Types of radiation present in the FEL Laboratory facility a.) X-rays b.) Gammas c.) Neutrons d.) Beta rays Biological effects of exposure to radiation Precautions and procedures to minimize exposure to radiation North Carolina regulations and DFELL accelerator license Dosimeters a.) Badges b.) Personal active dosimeters c.) Geiger counters d.) Ionization chambers e.) Local area ionization chambers f.) Area monitoring TLDs
2.)
3.) 4.)
5,) 6.) 7.) 8.)
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9.)
10.)
Warning signs, lights, and sirens a.) Posted signs b.) Radiation warning beacons and sirens Personnel protection system a.) Interlocks for tunnel and beam dump area access b.) Key system c.) Panic buttons and pull ropes d.) Search procedures e.) Emergency procedures
A facility tour will review the last three major topics, showing the trainees the actual hardware in question. The trainee will be required to pass a quiz on the material of the course. Operator training course The Operator training course consists of : • The general radiation worker training course • Additional topics outlined below • Hands-on apprenticeship under the guidance of a Class I operator
1.
RADIATION FUNDAMENTALS 1.1 Definitions 1.2 Introductory concepts 1.2.1 Structure of the atom 1.2.2 Mass and Energy 1.3 Ionizing Radiation–Introductory concepts 1.3.1 Biological effects due to ionizing radiation 1.3.2 Effects of ionizing radiation on materials 1.3.3 Detection of ionizing radiation 1.3.4 Accelerator produced radiation 1.3.5 Klystron produced radiation 1.3.6 Radiation from activated materials 1.4 Protective measures 1.4.1 Units of radiation 1.4.2 Action to reduce dose 37
1.4.3 Shielding for the accelerator 2. THE NATURAL RADIATION ENVIRONMENT 2.1 Cosmic rays 2.2 Terrestrial sources 2.2.1 Medical exposures 2.3 Summary 2.4 Biological effects of ionizing radiation 2.4.1 Cellular biology 2.4.2 Cancer biology 2.4.3 Causes of Cancer—what is known 2.4.4 Summary 2.4.5 Heredity and cancer induction 2.4.6 Fetal effects from radiation exposure 2.4.7 Acute effects REGULATIONS AND PROCEDURES 3.1 Organization 3.1.1 Duke Radiation Safety Office and Duke University Radiation Safety Committee 3.1.2 FEL lab Radiation Safety committee 3.1.3 Operations Supervisor Duties and Authority 3.1.4 Radiation Safety manager Duties and Authority 3.1.5 Operator duties and authority 3.2 Labeling and record keeping 3.2.1 Radiation warning signs 3.2.2 Radiation logbook 3.2.3 Radiation source logbook 3.2.4 Dosimeter logbook 3.3 Handling of sealed radioactive sources 3.4 Removal of activated components from beamlines RADIATION SAFETY SYSTEMS AT DFELL 4.1 Dosimeters 4.1.1 Film badges 4.1.2 Personal active dosimeters 4.1.3 Geiger counters 38
3.
4.
4.1.4 Ionization chambers 4.1.5 Local area ionization chambers 4.1.6 Area monitoring TLDs 4.1.7 Calibrating ionization chambers
4.2
Personnel protection system 4.2.1 Architecture 4.2.2 Interlocks for tunnel and beam dump access 4.2.3 Warning systems 4.2.4 The key system 4.2.5 Panic buttons and pull ropes 4.2.6 Search procedures 4.2.7 Restricted access modes 4.2.8 Maintenance of the system 4.2.9 Administrative procedures for system modification
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APPENDIX C—Beam Permit
The DFELL operates under a Beam Permit, which is used to document the conditions for operation of DFELL accelerators. The Beam Permit is created and issued by Duke Radiation Safety, and lists the pre-running conditions which must be met before accelerator operations are allowed, as well as the running conditions and Beam Permit Modifications which must be reviewed and signed off by accelerator operators on every operation shift. The beam permit also requires the review of all active Work Permits (see Appendix D), to ensure the pertinent ones are completed and signed before operations begin. A Beam Permit is issued: 1. After the passage of six months since the existing Beam Permit was issued. During extended shutdowns for upgrades, issuing of a new Beam Permit can be postponed until the shutdown is complete. 2. In the case of significant changes to an accelerator, shielding, or radiation safety equipment. A complete test of the PPS system is required before issuing a new Beam Permit. Following the issue and signing of the Beam Permit, modifications are allowed, with joint approval of Duke Radiation Safety, the DFELL Radiation Safety Manger, and the Operations Supervisor. Modifications and approvals are listed in the Beam Permit, which provides a record of all changes in accelerator operations. Prior to each operation shift, the AO on duty must review the Running Conditions and the Modifications, and check off that operations meet the Beam Permit conditions on the provided check-off sheet.
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APPENDIX D—Work Permit
The DFELL has a Work Permit procedure, intended to reduce the possibility of an accident due to poor communications. The work permit procedure is intended to ensure that multiple checks are carried out whenever changes are made to radiation safety systems, equipment and shielding. All work on shielding and PPS systems will require authorization, signed by the person requesting the work, submitted to the Operations Supervisor, and approved by the DFELL Radiation Safety Manager, before the work begins. After the work has been completed, the affected radiation safety items listed on the Work Permit must be inspected and signed off as safe to resume operations (Part 3), before the resumption of accelerator operations can be authorized (Part 4). The work permit is available from the RSM.
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