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SCHOOL OF EARTH, ATMOSPHERIC AND ENVIRONMENTAL SCIENCES UNIVERSITY OF MANCHESTER LOCAL RULES IONISING RADIATIONS (Open and Sealed Sources) 2004 Radiation Protection Supervisor Dr R. Burgess EMERGENCIES IN EMERGENCY: KEY 9999 ON A PUSH-BUTTON TELEPHONE AND GIVE DETAILS CLEARLY AND CONCISELY 1. FIRE INVOLVING SOURCES OF IONISING RADIATIONS Proceed as per the fire instructions for your School but remember to tell all parties concerned that radiation is involved. The possibility of Fire Brigade personnel and University Staff becoming contaminated should be kept in mind. This may involve the setting-up of a contamination zone for me and their equipment, so that a radiation check can be made before they leave the zone. 2. INJURY INVOLVING ACTUAL OR POSSIBLE CONTAMINATION FROM RADIOACTIVE MATERIALS (a) Serious injury Treatment of the patient takes priority over all decontamination procedures. Request the attendance of an ambulance, emphasising to the ambulance control that the casualty involved has been exposed to radioactive contamination. A competent person with knowledge of the type and extent of the radiation hazard should accompany the casualty to hospital. The Casualty Department should also be given forewarning that a potential radioactive contaminated victim is en route to the hospital. (b) Minor injury Provide first aid - then proceed as in 3 below. 2 3. ACCIDENTS AND INCIDENTS INVOLVING SOURCES OF IONISING RADIATIONS In the event of any accident or incident involving the use of any source of ionising radiation, the following people must be contacted immediately after the above action has been completed: (i) (ii) The School Radiation Protection Supervisor; and The Radiological Protection Adviser. In any emergency steps must always be taken to minimise the doses received from sources of penetrating radiations and also to avoid the spread of contamination from open sources of radioactive materials. 3 SCHOOL OF EARTH, ATMOSPHERIC AND ENVIRONMENTAL SCIENCES (SEALED AND UNSEALED SOURCE) LOCAL RULES FOR THE PROTECTION OF PERSONS EXPOSED TO IONISING RADIATIONS IN RESEARCH AND TEACHING SCHOOL RADIATION PROTECTION SUPERVISORS Dr R.Burgess Room G13 Telephone No.: Internal 53958 Home No.: 0161 427 1672 Dr C. Percival (Atmospheric Sciences) Telephone No Internal 63945 RADIOLOGICAL PROTECTION Radiological Protection Adviser Dr. S. Bidey Internal Phone No.: 56983 Enquiries Secretary Internal Phone No: 56980 Technicians Internal Phone No: 56982 Web address: http://intranet.man.ac.uk/rsd/personnel/hss/radio2.html The cover shows the International Radiation Symbol within the standard hazard warning triangle. This should be displayed at the entrance to all areas where ionising radiations are used or where radioactive materials are stored or discharged. 4 Within the School areas where work is carried out with radioactive material or radiation emitting equipment are as follows: 1. Work with sealed sources One gas chromatograph containing a Nickel-63 (10 mCi) source Phillips gas chromatograph type PU-4410 Serial No. GE 411341 – Room 1.25C (non-designated). Work with X-ray equipment – Room B14A (X-ray diffractometer) - Supervised and when necessary controlled. Work where there is an external hazard – Room G61 (neutron-irradiated rock samples) - Supervised. 4. Work where there is both an internal and external hazard – Rooms G69A (neutron irradiated rock samples) and Room B26 (Technetium-99 and Uranium238) - Supervised and when necessary controlled. 2. 3. 5 LABORATORY RULES - SEALED SOURCES 1. 2. Always USE the MINIMUM ACTIVITY SOURCE required for the experiment. SOURCES EMITTING PENETRATING RADIATIONS SHOULD NEVER BE MANIPULATED DIRECTLY BY HAND. To CONTAIN PENETRATING RADIATIONS use appropriate SHIELDING to keep DOSE RATES BELOW 2.5 µSvh-1 whenever reasonably practicable. WEAR YOUR FILM BADGE AND FINGER DOSIMETERS if these have been issued to you. Any SOURCE NOT PERMANENTLY MOUNTED should be KEPT in properly LABELLED CONTAINERS and in an APPROVED LOCKED STORE when not in use. All SOURCES should be ENGRAVED or otherwise permanently marked with a UNIQUE IDENTIFICATION CODE. If permanently mounted in a source holder, this should bear the identification mark along with details of the isotope, activity and a radiation trefoil if this is reasonably practicable. If a SOURCE is PERMANENTLY MOUNTED in a piece of equipment, it should NOT BE READILY REMOVABLE and the EQUIPMENT should have a suitable WARNING LABEL. DO A FULL MONITORING SURVEY of the LABORATORY when directed by your D.R.P.S. The results of these surveys should be recorded for future reference. KEEP ACCURATE RECORDS OF ALL RECEIPTS AND CURRENT STOCK. It is an offence under the Radioactive Substances Act 1993 not to have these UP TO DATE AT ALL TIMES. 10. LOCATION OF SOURCES should be CHECKED on at least a MONTHLY basis. For sources permanently mounted. For portable sources, every 24 hrs. In the event of any ACCIDENT or INCIDENT involving radioactive materials INFORM your RPS or RADIATION SAFETY UNIT IMMEDIATELY. 3. 4. 5. 6. 7. 8. 9. 11. 6 LABORATORY RULES - UNSEALED SOURCES 1. EATING, DRINKING, SMOKING, SNUFF-TAKING, APPLYING COSMETICS etc. are FORBIDDEN. NO MOUTH OPERATIONS, pipetting etc. WEAR LABORATORY COATS and other protective clothing if necessary. WEAR GLOVES when there is a possibility of the hands becoming contaminated. Then USE TISSUES when handling taps and switches, etc. WEAR YOUR FILM BADGE and FINGER DOSIMETERS if these have been issued to you. KEEP PERSONAL BELONGINGS AWAY FROM RADIOACTIVE AREAS. To CONTAIN CONTAMINATION use CLING FILM and TRAYS. Keep CONTAMINATION AS LOW AS REASONABLY ACHIEVABLE and BELOW PRESCRIBED LIMITS. To CONTAIN RADIOACTIVE GAS, DUST or FUMES use an APPROVED FUME CUPBOARD or GLOVE BOX. To CONTAIN PENETRATING RADIATIONS use appropriate SHIELDING to keep DOSE RATES BELOW 2.5µSvh-1 whenever reasonably practicable. MONITOR YOURSELF and the immediate WORK AREA at the end of each work session, whenever radioactive substances have been used. ALWAYS WASH YOUR HANDS after working with radioactive substances. DO A FULL MONITORING SURVEY of the LABORATORY when directed by your D.R.P.S. The results of these surveys should be recorded for future reference. THE MINIMUM OF EQUIPMENT should be kept in the RADIOISOTOPE AREA. Wherever possible, equipment should be clearly marked and set aside solely for use with radioisotopes. Any such tools or equipment should be kept in the store. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 7 14. SEGREGATE CONTAMINATED ITEMS and CLEAN THOROUGHLY. DO NOT REMOVE ANY ITEM from the radioisotope area until it has been MONITORED and found to be FREE OF CONTAMINATION. KEEP RADIOACTIVE MATERIALS IN PROPERLY LABELLED CONTAINERS IN THE STORE - see D.R.P.S. KEEP ACCURATE RECORDS OF ALL RECEIPTS, CURRENT STOCK AND WASTE. It is an offence under the Radioactive Substances Act 1993 not to have these UP-TO-DATE AT ALL TIMES. In the event of any ACCIDENT or INCIDENT involving radioactive materials INFORM your RPS or the RADIATION SAFETY UNIT IMMEDIATELY. 15. 16. 17. 8 Monitoring - General Guidelines A suitable monitor is provided for use when working with radioactive substances, both for use whilst you are working and for monitoring yourself and the immediate work area at the end of each work session. This routine monitoring does not need to be recorded but is recommended. A full monitoring survey of the laboratory should be performed on a regular basis and this survey should be recorded. A monitoring log book for these surveys should be kept . The frequency of this survey will be dependent upon: the designation of the area; the amount of radioactive work and the frequency of the radioactive work. The following should be used as a guideline: non-designated area supervised area controlled area monthly weekly at least weekly and the same day after loading /unloading of furnaces etc. Monitors Mini E Mini 5.44A Mini 5.44B hard betas and beta-gammas, e.g. P-32, Rb-86, I-131, Na-22 X-ray emitters, gamma emitters & hard betas, e.g. I-125, Tc-99m, Na-22, Co-57, P-32. As for 5.44A and in addition, Cr-51 Contamination Monitoring There should always be a suitable contamination monitor available in areas where unsealed sources are used. It should have a check source with it, so that it can be tested before and during use, to make certain that the monitor is functioning correctly. Every time you handle radioactive rock samples you should use the appropriate contamination monitor to monitor your immediate work area - bench top, equipment, bench front and floor - at the end of each work session. Any contamination found should be removed immediately, or if this is not practicable, a suitable warning notice should be displayed. On no account should contamination be left unmarked which would pose a hazard to others. 9 At regular intervals, a full monitoring survey should be carried out to establish that:(a) the area is correctly designated (on grounds of contamination); and (b) any contamination that has occurred has been dealt with efficiently and has not been spread to - cupboard doors, floors, door handles, etc. These monitoring surveys have to be recorded in the monitoring log and must be carried out after every loading/unloading and whenever open source material is handled, 10 Laboratory Grading Designation of Areas Three types of radiation area are recognised by the Ionising Radiation Regulations, 1999: Controlled Area where an employee is likely to receive doses of radiation in excess of three-tenths of any dose limit where an employee is likely to receive doses of radiation in excess of one-tenth but not exceeding three-tenths of any dose limit where an employee is unlikely to receive doses of radiation in excess of one-tenth of any dose limit. Supervised Area Non-designated Area In the School we have all three. These are: 1. 2. Work with X-ray equipment - B14A. (Supervised and when necessary controlled) Work where there is both an internal and external hazard - G69A and B26 (Supervised and when necessary controlled) 3. 3. Work where there is an external hazard only - G61 (non-designated). Work with Ni-63 sealed sources – 1.25C (non-designated). 11 External Hazard A controlled area is required where the instantaneous dose is greater than 7.5 µSvh -1 to the body and greater than 75 µSvh-1 to the hands. A supervised area is required where the instantaneous dose rate exceeds 2.5 µSvh -1 to the body and 25 µSvh-1 to the hands. A non-designated area can be used where the instantaneous dose rates do not exceed 2.5 µSvh-1 to the body or 25 µSvh-1 to the hands. X-rays THIS INFORMATION IS IN SCHOOL’S LOCAL RULES FOR X-RAY EQUIPMENT. Use of unsealed sources presenting a combination of internal and external hazards When an area is required to be designated as a supervised area, either: (a) (b) in relation to both external and internal radiation; or in relation to internal radiation by reason that both the air concentration and the surface contamination exceed one third of the levels that would require a controlled area on their own then that area should be designated as a controlled area. 12 Access to Laboratories The entrance to Designated Radiation Laboratories must bear the appropriate warning notice and, if required, a notice limiting access. Access to radiation areas is restricted as follows:(a) controlled areas classified radiation workers and others following a written system of work. registered radiation workers and other persons whose presence, work or duties can be so controlled that they will not be exposed to significant amounts of radiation. The latter must be advised as to how they may fulfil this requirement. (c) non-designated no restriction on the grounds of radiation hazard (b) supervised areas Access by Service Personnel Before work is undertaken on any article, equipment, structure or service where a radiation hazard is indicated, the School’s Radiation Protection Supervisor (RPS) or his/her deputy must be contacted in order that he/she may summon assistance from the Radiological Safety Unit (RSU). Work must not start until clearance has been given by RSU, and any recommended protective measures implemented. 13 Storage of Radioisotopes It is essential that radioactive materials should be kept under conditions which present no radiation hazard, particularly to non-radiation workers. A requirement of the Radioactive Substances Act 1993, also demands that all necessary measures be taken to prevent any person having access to radioactive materials without authority, and that when not in use materials be, where this is reasonably practicable, securely stored in a locked store or designated locked cupboard i. e. (within G69A). A locked store, suitably shielded, is provided within G69A. This is set aside solely for the purpose of storing radioactive material. Every effort must be made to prevent sources being damaged, broken open or spilled, and steps must be taken to minimise the effect of any accident which might occur. Suitable shielding, usually lead, should be sufficient to keep the dose rate on the outside of the store below 7.5 µSvh-1, and if reasonably practicable, below 2.5 µSvh-1. 14 Record Keeping The following records are required by the Ionising Radiations Regulations 1999, or by Certificates of Registration or Authorisation issued under the Radioactive Substances Act 1993, or as called for by the Approved Code of Practice. They have to be kept for a varying number of years, and for some the School has a responsibility. Record Keeper Non-Classified Personnel Dose Assessment Records Monitor tests (14 monthly) Leakage tests (26 monthly) 2 yrs from date of report RSU/School Time to be retained 2 yrs from date of test RSU/School 3 yrs from date of test RSU/School Laboratory monitoring Isotope records relating to ordering, storing & disposal of radioactive materials RSUS/School 2 years from date of report Dept. 2 years from date of last entry RSU - Radiological Safety Unit 15 General Information Ionising radiations are a natural component of the environment in which we live. They come from constituents of the air we breathe, the ground we walk on and the food we eat. We are also bombarded by a never-ending stream of cosmic radiation from the sun and space. Today, we may also be exposed to varying levels of man-made radiation, the most significant of which is medical X-rays, and everyone appreciates the benefits which they have brought us. You, by the nature of your work, may be exposed to higher levels of radiation than the general public, and an important principle of radiation protection is that the benefits of the work that you do should far outweigh any risks involved. The purpose of this booklet is to provide radiation workers in the School of Earth, Atmospheric and Environmental Sciences with useful information on ionising radiations and details of the procedures they should follow to ensure safe working practices and compliance with the law. If the procedures are strictly adhered to, then the risks associated with your work with ionising radiations and your exposures to them should be minimal. Legislation & Codes of Practice Work with ionising radiations is now covered by three main Acts of Parliament. These are: (a) (b) (c) Health and Safety at Work etc. Act 1974 - Ionising Radiations Regulations 1999; Radioactive Substances Act 1993; and Radioactive Materials (Road Transport) (Great Britain) Regulations 1996. 16 The Health and Safety at Work etc. Act introduced a new concept into safety legislation, in that for the first time, the employee as well as the employer has responsibilities to himself and to others who may be affected, not only by the work he performs, but also by any failure to perform his duties. The detailed requirements for work with ionising radiations under the Health and Safety at Work etc. Act are provided by the Ionising Radiations Regulations 1999 and the Approved Code of Practice for the protection of persons against ionising radiations arising from any work activity. The Radioactive Substances Act 1993 was designed to control the use of radioactive materials, and all University buildings where radioactive materials are used hold Registration Certificates, issued to them by the Environment Agency under this Act. These spell out the radioisotopes which are allowed to be used and the amounts which can be held in store at any one time. The Environment Agency also issue Authorisation Certificates for the disposal of radioactive waste, which place limits on the amount which can be disposed of at any one time, and also specify the permitted means of disposal. A notice indicating the various limits and conditions of the Certificates as they affect the School of Earth, Atmospheric and Environmental Sciences should be displayed. It is important that the School keeps within the limits of the Environment Certificates. The Radioactive Substances (carriage by Road) Regulations 1974 were brought out under the Radioactive Substances Act 1948 and now the Radioactive Materials (Road Transport) (Great Britain) Regulations 1996, together with the Ionising Radiation Regulations 1999 govern the movement and transport of radioactive materials. This subject is dealt with in detail in APPENDIX B. Copies of the above documents are held by Radiation Protection Supervisor and should be available for viewing at any reasonable time. These local rules and requirements of the Ionising Radiation Regulations are based upon all current Regulations, and provide the radiation worker with guidance which should enable him to observe them. There are enforcement agencies - The Health and Safety Executive and the Environment Agency - which, from time to time, inspect work with ionising radiations at the School to ensure that the Regulations are complied with. They have the power to enter premises unannounced and to withdraw licences or issue prohibition notices if they find an unsatisfactory situation. 17 Radiation Worker The individual radiation worker, before starting work with ionising radiations, should familiarise himself with all pertinent local rules, and with the physical, chemical and biological properties of the radioactive material, or physical properties of other ionising radiations, which he proposes to use. The radiation worker has a personal responsibility to protect both himself and others from any hazard arising from his work, and he must not expose himself or others to ionising radiations to a greater extent than is reasonably necessary for the purpose of his work. Dose Limits and Assessments One great difficulty in working with ionising radiations is that one cannot sense their presence, and one can be subjected to a lethal dose of radiation (5Gy to the whole body) and not be aware of it until some time after the event. Early workers found, to their cost, the hazards of working with ionising radiations, and international concern led to the setting up of the International Commission on Radiological Protection (ICRP) in 1928. The Commission has brought together all the information available on the biological effects of ionising radiations, and has then recommended dose limits and good working practices in order to minimise the risks from working with ionising radiations. ICRP recommendations form the basis of all the national regulations. Biological Effects These can be divided into two groups: somatic effects which affect the person irradiated, and genetic effects where it is the offspring of the person irradiated who is affected, because of damage to germ cells in the reproductive organs. The cells of the body which are most likely to be affected by radiation are those that are dividing, and therefore, those parts of the body where there is a high cell turnover as most sensitive to radiation damage, e.g. blood forming organs, gonads, gut wall, skin. It also follows that growing animals, especially the unborn foetus, are more sensitive to radiation than adults. Therefore, particular consideration is given in setting dose limits for pregnant women and women of reproductive capacity and it is essential that a female worker informs her Radiation Protection Supervisor as soon as she suspects she is pregnant. 18 The ICRP has introduced new terms - stochastic and non-stochastic - to describe the effects of ionising radiations. The term stochastic relates to those effects when the probability of the effect occurring is dependent upon the dose received, i.e. the higher the dose received the greater the risk of the effect occurring. The term non-stochastic relates to effects which only occur after a certain dose has been received, and where the severity of the effect is directly related to the dose received. The most obvious stochastic effects are the development of cancers. Examples of non-stochastic effects are the development of cataracts (15Gy to the lens of the eye); sterility in men (3Gy to the gonads); and death (5Gy to the whole body). All the information we have on the effects of radiation is based upon relatively high exposures. This is because of the long latent period of most cancers and the fact that cancer is such a common natural cause of death that it is virtually impossible to distinguish between radiation induced cancers and natural cancers. One therefore requires a large number of additional cancers induced in order to obtain statistically significant results. Risk estimates have been based upon these high exposures, and it has been assumed that there is a linear relationship between risks and dose, such that even the smallest dose carries some risk. This may be an over-cautious approach, but it is the basis upon which the dose limits recommended by the ICRP have been set. Dose Limits The dose limits recommended by the ICRP, and adopted by our own legislators, are constantly under review as our knowledge of the effects of radiation improves. They are set on the basis that a lifetime's exposure to the maximum dose limits will not result in any non-stochastic effects, and that the risk of stochastic effects can be kept to an acceptable level for the average exposure of a radiation worker (4 mSv/annum). Exposure up to the dose limits is not considered acceptable, and all doses should be kept AS LOW AS REASONABLY ACHIEVABLE. Dose Limits for Radiation Workers Whole body exposure Individual organ or tissue or hands Lens of the eye 50 mSv/annum 500 mSv/annum 150 mSv/annum 19 Women - abdomen of woman of reproductive capacity - dose constraint applied to the foetus 13 mSv/3 month 1 mSv Dose limits for members of the general public have generally been set at 1/10th of the above values, but it is now widely accepted that their whole body exposure should be restricted to 1 mSv/annum, except in exceptional circumstances. It is worth noting that the average individual exposure from background radiation is 2.15 mSv/annum. This is predominantly from natural sources, and can vary considerably depending upon where you live. Personnel Dose Assessments Any person who is likely to receive a dose of radiation in excess of three-tenths of any relevant dose limit is required to be a classified radiation worker and must have his exposure to radiation monitored. Also, any worker who works in a controlled area either has to be classified or work under a System of Work, and this normally entails personal monitoring. All staff are monitored by film badge, unless their possible exposure is negligible. It is important that, if you are issued with a film badge, it should be worn at all times whilst working with ionising radiations, and worn correctly (see Appendix C .). A few people who come into close contact with particularly penetrating radiations will be requested to wear finger thermoluminescent dosimeters (TLD's), and they will be given guidance as to their usage at the time. The minimum detectable level of radiation on a film or TLD is 0.2 mSv and, the official investigation level for radiation exposures is 15 mSv. 20 Restriction of Exposure In order to minimise the exposure to ionising radiations, one needs to appreciate the properties of the ionising radiations and the two principal hazards which they can present. We can be irradiated by a source of radiation which is outside the body - this presents us with an external hazard, or we can accidentally incorporate radioactive materials into the body - this presents us with an internal hazard. All hazards from ionising radiations can be minimised by using the lowest activity source or energy of X-rays consistent with experimental requirements. External Hazard External hazards can arise from any source of penetrating radiation, e.g. X-ray sets, gamma emitters, neutron sources and hard beta emitters. The more penetrating the radiation, generally the greater the hazard, although in some ways hard betas and soft X-rays, which are absorbed by the surface layers of tissue, can be more hazardous than more penetrating radiations which might go straight through the body (medical X-rays). There can only be a hazard from X-ray sets whilst the set is switched on. Sealed sources, used under normal conditions, should only present an external hazard, but this will always be present. Open sources can also present an external hazard, and as with other external radiation hazards, doses can be minimised by:(a) (b) (c) use of effective shielding; keeping one's distance; and exposing oneself for the minimum of time. Inverse Square Law The dose rate associated with any point source of gamma or X-radiation is inversely proportional to the square of the distance from the source. D 1 r2 21 Therefore, by doubling the distance from the source, the dose rate will be reduced by a factor of 4. Always remember that closeness endangers - distance protects. A useful expression for calculating the approximate dose rate from a gamma source is:D = ME6r2 D is dose rate in µSvh-1 M is activity in MBq E is energy/disintegration in MeV r is distance from source in metres This of course assumes no shielding, and a monitor should always be used to establish the true dose rate . The expression is useful, however, in estimating how much shielding you may require. The table below gives some examples of dose rates at 1 m from 10 MBq sources, using information on the energy and intensity of their gamma emissions from ICRP publication 38. Isotope - dose rate at 1 metre in µSvh-1 for 10 MBq source 3.65 6.86 0.05 1.98 0.21 4.17 0.07 0.63 Na-22 Na-24 Cr-51 Fe-59 Co-57 Co-60 I-125 I-131 Shielding Beta particles are best shielded by materials of low atomic number to prevent the production of bremsstrahlung: Perspex makes good shields, because it is robust and easily worked. Glass is also very effective, and thick walled glass vessels are particularly useful. The table below shows the thickness required for complete shielding. 22 E max (MeV) Glass Perspex 0.5 1mm 2mm 1.0 2mm 4mm 2.0 4mm 7mm 3.0 7mm 12mm Gamma rays and X-rays are far more penetrating than beta particles of the same energy and require dense shielding materials - lead is the material which is usually used. They are attenuated exponentially, and a knowledge of the half-value layer (HVL) or tenth-value layer (TVL) is useful in determining the amount of shielding required. 1 HVL is the thickness required to reduce the intensity to one half the incident value and 1 TVL is the thickness needed to reduce the intensity to one tenth the incident value. Some approximate values of HVL and TVL are given in the table below. Gamma energy MeV 0.5 1.0 1.5 2.0 millimetres of lead shielding HVL 4 11 15 19 TVL 12.5 35 50 60 The detailed precautions which are provided for work with X-ray crystallographic equipment are spelled out in School of Earth Sciences, Atmospheric and Environmental Sciences Ionising Radiation Local Rules for X-ray Crystallography. The good working practices required for work with sealed sources are given: in the laboratory rules for sealed sources (see Appendix D). 23 Internal Hazard When working with open or unsealed sources of radioactive material, as well as having a possible external hazard to contend with, one is faced with the possibility that radioactive material might find its way into the body. One would then be faced with an internal radiation hazard, and shielding, distance and time would no longer afford protection. Only by a combination of physical half-life and biological half-life can the material be eliminated from the body - some may remain there forever. It can easily be appreciated that small amounts of radioactive material inside the body can be more harmful than much larger amounts outside the body. Every effort must be made, therefore, to prevent radioactive material from entering the body. Routes of entry into the body are via the mouth by inhalation or ingestion and through the skin via cuts or absorption. Internal contamination can be avoided by adopting good working practices, and by following some basic precautions, such as:1. 2. 3. 4. 5. use of materials of minimum radiotoxicity; presence in the laboratory of the minimum quantities; containment, to prevent spread of contamination; cleanliness and good housekeeping; and use of appropriate protective equipment. The good working practices required for work with unsealed sources are spelt out in the Laboratory Rules for this work (see APPENDIX E ). Detailed guidance notes for all the common isotopes should be available from your Radiation Protection Supervisor. A useful indication of the radiotoxicity of an isotope is its annual limit of intake (ALI). This is the amount which, if taken into the body in a year, will result in the individual receiving the full annual dose limit from this source of radiation alone. 24 Unsealed Sources (Neutron activated "rock" samples.) The rock fragments are small enough (less than 3mm) to be regarded as "dispersable material "and thus can be accounted for by keeping precise records of received material and waste in accordance with the Code of Practice IRR 1999, Reg. 19,para. 112, 113, 115, 119(c) and 121. In addition it is prudent to make a record of individual sample details in the Irradiated Sample Log Book . This log must contain all information necessary in order to that the exact location of individual samples can be ascertained , i.e. where and when loaded, or whether in storage or awaiting disposal after runs are finished, and the date when the waste leaves the School. Failure to keep this information up to date may lead to a delay in tracing the location of a sample. The Radiation Protection Supervisor will keep a record of irradiations arrivals and their activity when received. If any full or partial irradiations are sent to other institutions then all relevant information regarding this will be logged. 25 Sealed Sources A record of all sealed sources in a School should be kept by the Radiation Protection Supervisor. All sealed sources are affected by this record keeping requirement - even reference sources and those in liquid scintillation counters. The exemption limits of the Radioactive Substances Act are very low indeed (0.4 Bq/g and, therefore, of no help in easing this requirement). The whereabouts of all portable sealed sources must be checked every 24hrs and ones installed in equipment every month. All such checks must be recorded in a log to prove compliance with the regulations. 26 Waste Disposal Solid Waste. Waste is disposed of by School of Earth, Atmospheric and Environmental Sciences by Methods 1 and 2. 1. 2. Disposal with ordinary waste. Disposal to the Private waste disposal companies licensed to deal with radioactive substances. This is carried out via RSU. Disposal with ordinary waste Small amounts of solid radioactive waste are permitted to be disposed of with ordinary waste. The limits for such 'dustbin disposals' are given in the table below:- Limit H-3 & C-14 Other beta & gamma emitters Alpha emitters & Sr-90 In 0.1m3 per article 4000kBq 400kBq 400kBq 40kBq None None Please consult the Radiation Protection Supervisor before disposing of waste by this route, as radioactive waste disposal can be a very sensitive subject. Aqueous waste (beta and gamma emitters only) may be disposed of via a designated sink in room B26 up to a maximum of 4MBq per calendar month. For disposal of aqueous waste containing alpha emitters, tritium and C-14 aqueous waste, contact RSU. 27 IMPORTANT The law requires the maintenance of suitable records for the discharge of any form of radioactive waste. Each and every user must ensure that such records are properly kept. Failure to do so, or to comply with the other requirements of the Radioactive Substances Act 1993, could result in prosecution with penalties of fines and imprisonment. A " dustbin" log must be kept if this route is used. APPENDIX A GENERAL INFORMATION Radiation Units With the introduction of the Ionising Radiations Regulations 1999, it has been obligatory to adopt the International System of Units (SI) for use with ionising radiations. These will be used throughout the local rules, but conversion factors to the old units will be found below in this section, Activity The SI unit of activity is the Becquerel, and is equal to one disintegration per second. This is a very small unit in relation to the Curie, which is the activity of 1g of radium, equivalent to 3.7 x 1010 dps. Absorbed Dose When ionising radiations pass through matter, some or all of the energy they possess is given up, and the absorbed dose is a measure of this energy deposition. In the SI units, 1 gray (Gy) is defined as the energy deposition of 1 joule per kilogram. Dose Equivalent For the same absorbed dose of radiation, some types of ionising radiations have a greater biological effectiveness. To allow for this quality factors have been introduced which reflect the ability of different ionising radiations to cause damage, and if we multiply the absorbed dose by the appropriate quality factor, we arrive at what is called the Dose Equivalent. This is measured in Sieverts. For work with , and X-ray 28 emissions, this factor has been assigned a value of 1 and, therefore, will be of no concern to most people. A summary of quality factor values is given below. Type of radiation , and X-ray emissions Thermal neutrons Fast neutrons and protons particles Quality Factor 1 2.3 10 20 29 Summary of units Quantity New SI Unit Old Unit _________________________________________________________________ Activity becquerel - Bq curie - Ci (1 disintegration s-1) (3.7 x 1010 disintegrations s-1) rad (0.01 J.kg-1) Absorbed Dose gray - Gy (1 J.kg-1) Dose Equivalent sievert - Sv rem (Gy x quality factor) (rad x quality factor) Prefixes used with Si Units Prefix tera giga mega kilo milli micro nano Some useful conversions Symbol T G M k m µ n Factor 1012 109 106 103 10-3 10-6 10-9 Dose Equivalent 1.0 Sv 50mSv 200µSv 7.5µ Svh-1 = = = = 100 rem 5.0 rem 0 20mrem 0.75mrem.h-1 1 µCi = 37 kBq 1 mCi = 37 MBq 1.0 Ci = 37 GBq Activity 1 kBq = 27 nCi 1 MBq = 27µCi 1 GBq = 27 mCi 30 APPENDIX B Transport and Movement of Radioactive Substances Definitions 'Movement' shall be taken to mean all movements of radioactive substances by hand inside a University building and outside a University building, so long as the movement is not in a public place. 'Transport' shall be taken to mean all movements of radioactive substances through a public place, whether on a conveyance or not. This, therefore, includes movements by hand through a public place. 'Radioactive substance' means any substance having an activity concentration of more than 70 Bq g-1 (for transport purposes only). Movement of Radioactive Substances It is not permissible to take a vial, flask or sample tube containing radioactive substances from one laboratory to another without first putting them into suitable receptacles. A suitable receptacle most provide adequate shielding for the person carrying it, and be robust enough not to break on being dropped. If there is the possibility of a spill, then sufficient absorbent material should be enclosed in the receptacle to contain it, or the receptacle should be adequately sealed to prevent leakage. 31 The following containers, or combinations of them, could be considered suitable:- (a) (b) (c) (d) a screw top plastic or metal container - new Amersham cans ideal; a plastic snap top container; a push fit plastic or metal container adequately taped up; a lead pot adequately taped up (would require absorbent packing for liquids in glass vials if used on its own; and (e) for sealed sources, the lockable money boxes would be suitable. Although the radioactive substance itself should be adequately labelled, no additional information or specific labelling of the receptacle is required for the movement of radioactive substances. However, if the material is likely to remain in its receptacle for some time, or left unattended, then some indication of its contents would be advisable. Any packaging/receptacle used for the transport of excepted or Type A packages in line with IAEA Regulations 1985 can be taken to be suitable for the movement of a radioactive substance. Transport of Radioactive Substances These guidelines are intended for the transport of limited quantities of radioactive materials by road or by hand when in a public place. For transport by air or post, special authorisation may be required, and you should contact the Radiological Protection Unit well in advance so that the necessary arrangements can be made. See the RPS (or RSU) for limits on activity that may be transported as an excepted package, or Type A, and on the documentation and packaging requirements. See the RPS or RSU before organising transportation. He will advise you on the type of package excepted, Type A, etc., the activity limits and surface dose rates. You should find that the vast majority of radioactive substances that need to be transported around the University or to another establishment can be transported as excepted packages. 32 General Packaging Requirements for Excepted Packages (a) When necessary, shielding should be provided to ensure that the dose rate at the surface of the excepted package does not exceed 5 µSvh -1. For instruments or articles, there is the additional restriction that the does rate 10 cm from any point on the external surface of any unpackaged instrument or article is not greater than 0.1mSvh-1. Non-fixed contamination on the external surface of the excepted package shall not exceed:(i) 0.4 Bq cm-2 for beta, gamma and low toxicity alpha emitters, e.g. natural Uranium and thorium; and (ii) 0.04 Bq cm-2 for all other alpha emitters. The package shall bear the marking "Radioactive" on an internal surface in such a manner that a warning of the presence of radioactive material is visible on opening the package. The package shall be so designed in relation to its mass, volume and shape that it can be easily and safely handled and retain its contents under conditions likely to be encountered in routine transport (e.g. taking into account acceleration, vibration, braking etc.) As far as practicable, the packaging shall be so designed and finished that the external surfaces are free from protruding features and can be easily decontaminated. As far as practicable, the outer layer of the package shall be so designed as to prevent the collection and retention of water. Any features added to the package at the time of transport, which are not part of the package, shall not reduce its safety. The materials of the packaging and any components or structures shall be physically and chemically compatible with each other and with the radioactive contents. Account shall be taken of their behaviour under irradiation, when applicable. In addition to the radioactive properties, any other dangerous properties of the contents of the package, such as explosiveness, flammability, pyrophoricity, chemical toxicity and corrosiveness, shall be taken into account in the packaging. (Also note any additional labelling requirements etc. that might be required by the relevant Transport Regulations for dangerous goods). (b) (c) (d) (e) (f) (g) (h) (i) 33 Transport Documents/Labelling Requirements for Excepted Packages (a) All items and materials transported as excepted packages shall be described in the transport documents as "RADIOACTIVE MATERIAL, EXCEPTED PACKAGE", and shall include the United Nations Number "2910" and the proper shipping name of the substance, as appropriate, e.g. LIMITED QUANTITY OF MATERIAL, INSTRUMENTS OR ARTICLES. The information that should accompany an excepted package being transported should include:(i) a description of the radioactive substance, e.g. the radioisotope, its quantity and physical form etc.; and (ii) any additional information which would be required to enable the person opening it to do so safely. It is recommended that the most effective way of tackling the documentation is to use a label (see Fig. 1), appropriately filled in, attached to the external surface of the excepted package. Any additional information that is required could be in an accompanying letter, or as a technical note to be found immediately on opening the package (i.e. before gaining access to any containment system inside the package). FIG. 1. - Example of label for external surface of excepted package RADIOACTIVE MATERIAL, EXCEPTED PACKAGE 2910 - LIMITED QUANTITY OF MATERIAL Date: ................. Physical form: ............ Isotope: .............. Chemical form: ............ Activity: ............. The MANCHESTER UNIVERSITY, SCHOOL OF EARTH, ATMOSPHERIC & ENVIRONMENTAL SCIENCES There is no requirement for the placarding of vehicles, either internally or externally, when transporting excepted amounts of radioactive material. However, it has always been considered good practice to carry an internal fireproof placard when transporting radioactive materials by car. Before transporting any radioactive material by car, you should check to see that this does not invalidate your car insurance policy. (b) 34 Transport of Type A Packages The packaging requirements for Type A packages are more stringent in that they require the package to satisfy various performance tests to demonstrate an ability to withstand the normal conditions of transport. The School has some reusable Type A packages. See the RPS for these. There are also different labelling requirements and the need for a consignment certificate. These will also be dealt with by Radiological Safety Unit or the RPS as the need arises. 35 APPENDIX C SCHOOL OF EARTH, ATMOSPHERIC AND ENVIRONMENTAL SCIENCES NOTES ON THE USE OF RADIATION MONITORING FILMS 1. Your film and film badge cassette are enclosed. All films bear the user’s name and identification number, and you should only wear films with which you are issued. You should never wear another person's film. Films should always be worn in the special cassettes. They should be inserted correctly in the cassette, i.e. with the name and number fully visible in the open window at the front of the cassette. It is important that they should not be turned in the cassette during an exposure period. If a film has been inserted incorrectly it should be left in this position for the remainder of that period and the matter reported when the films are collected. 3. Film badges should not be worn, or retained, for longer than the set period of issue (eight weeks), as doses estimated on such films cannot be assessed with any accuracy due to the effect of age on the emulsion. For an accurate assessment of dose it is essential that films are exposed in cassettes which have all their filters intact and in their correct position. If you suspect yours of being faulty in any way contact your Radiation Protection Supervisor. The cassette is only on loan to you. It should be returned when you leave the University or when monitoring is discontinued. 5. Your film badge should be worn at all times when exposure to ionising radiations is likely. In general, they are worn on either lapel of your laboratory coat. If, however, you feel that some other part of your body receives a larger dose it should be worn as near that site as possible. 6. Care should be taken to avoid exposure of films to ionising radiations when they are not being worn, particularly when they are not in cassettes. Films should be handled with care. Any action which permits fogging, e.g. piercing with pins, is liable to render them useless. Bending of films, exposure to excessive heat, etc., is also liable to produce blackening. 2. 4. 7. 36 APPENDIX D LABORATORY RULES - SEALED SOURCES 1. 2. Always USE the MINIMUM ACTIVITY SOURCE required for the experiment. SOURCES EMITTING PENETRATING RADIATIONS SHOULD NEVER BE MANIPULATED DIRECTLY BY HAND. To CONTAIN PENETRATING RADIATIONS use appropriate SHIELDING to keep DOSE RATES BELOW 2.5 µSvh-1 whenever reasonably practicable. WEAR YOUR FILM BADGE AND FINGER DOSIMETERS if these have been issued to you. 5. Any SOURCE NOT PERMANENTLY MOUNTED should be KEPT in properly LABELLED CONTAINERS and in an APPROVED LOCKED STORE when not in use. 6. All SOURCES should be ENGRAVED or otherwise permanently marked with a UNIQUE IDENTIFICATION CODE. If permanently mounted in a source holder, this should bear the identification mark along with details of the isotope, activity and a radiation trefoil if this is reasonably practicable. If a SOURCE is PERMANENTLY MOUNTED in a piece of equipment, it should NOT BE READILY REMOVABLE and the EQUIPMENT should have a suitable WARNING LABEL. DO A FULL MONITORING SURVEY of the LABORATORY when directed by your D.R.P.S. The results of these surveys should be recorded for future reference. KEEP ACCURATE RECORDS OF ALL RECEIPTS AND CURRENT STOCK. It is an offence under the Radioactive Substances Act 1993 not to have these UP TO DATE AT ALL TIMES. 10. LOCATION OF SOURCES should be CHECKED on at least a MONTHLY basis. For sources permanently mounted. For portable sources, every 24 hrs. In the event of any ACCIDENT or INCIDENT involving radioactive materials INFORM your RPS or RADIATION SAFETY UNIT IMMEDIATELY. 3. 4. 7. 8. 9. 11. 37 Further information can be found in the local rules, and help and guidance is always available from Safety Services - telephone numbers below: Safety Services: Your Radiation Protection Supervisor (RP.S.) is: Dr R. Burgess Tel. Internal: 53958 Home: 0161 427 1672 RADIOLOGICAL PROTECTION Radiological Protection Adviser Dr. S. Bidey Internal Phone No.: 55177 Enquiries Secretary Internal Phone No: 56980 Technicians Internal Phone No: 56982 38 APPENDIX E LABORATORY RULES - UNSEALED SOURCES 1. EATING, DRINKING, SMOKING, SNUFF-TAKING, APPLYING COSMETICS etc. are FORBIDDEN. NO MOUTH OPERATIONS, pipetting etc. WEAR LABORATORY COATS and other protective clothing if necessary. WEAR GLOVES when there is a possibility of the hands becoming contaminated. Then USE TISSUES when handling taps and switches, etc. 5. WEAR YOUR FILM BADGE and FINGER DOSIMETERS if these have been issued to you. KEEP PERSONAL BELONGINGS AWAY FROM RADIOACTIVE AREAS. To CONTAIN CONTAMINATION use CLINGFILM and TRAYS. Keep CONTAMINATION AS LOW AS REASONABLY ACHIEVABLE and BELOW PRESCRIBED LIMITS. To CONTAIN RADIOACTIVE GAS, DUST or FUMES use an APPROVED FUME CUPBOARD or GLOVE BOX. To CONTAIN PENETRATING RADIATIONS use appropriate SHIELDING to keep DOSE RATES BELOW 2.5µSvh-1 whenever reasonably practicable. MONITOR YOURSELF and the immediate WORK AREA at the end of each work session, whenever radioactive substances have been used. ALWAYS WASH YOUR HANDS after working with radioactive substances. DO A FULL MONITORING SURVEY of the LABORATORY when directed by your RPS. The results of these surveys should be recorded for future reference. 2. 3. 4. 6. 7. 8. 9. 10. 11. 12. 39 13. THE MINIMUM OF EQUIPMENT should be kept in the RADIOISOTOPE AREA. Wherever possible, equipment should be clearly marked and set aside solely for use with radioisotopes. Any such tools or equipment should be kept in the store. 14. SEGREGATE CONTAMINATED ITEMS and CLEAN THOROUGHLY. DO NOT REMOVE ANY ITEM from the radioisotope area until it has been MONITORED and found to be FREE OF CONTAMINATION. KEEP RADIOACTIVE MATERIALS IN PROPERLY LABELLED CONTAINERS IN THE STORE - see RPS. KEEP ACCURATE RECORDS OF ALL RECEIPTS, CURRENT STOCK AND WASTE. It is an offence under the Radioactive Substances Act 1993 not to have these UP-TO-DATE AT ALL TIMES. In the event of any ACCIDENT or INCIDENT involving radioactive materials INFORM your RPS or the RADIATION SAFETY UNIT IMMEDIATELY. 15. 16. 17. Further information on monitoring, dealing with spills and the disposal of waste etc. can be found in the Local Rules and help and guidance is always available from the Radiation Safety Unit - telephone numbers below. Radiation Safety Unit: Your School Radiation Protection Supervisor (RPS) is: R. Burgess Tel: Internal: 53958 Home: 0161 427 1672 40
"DEPARTMENT OF EARTH SCIENCES"