Brookhaven Technical Basis Document for the Internal Dosimetry

Brookhaven Technical Basis Document for the Internal Dosimetry Program (2004) Casper Sun, Ph.D. CHP CASPER@BNL.GOV Radiological Control Division Brookhaven National Laboratory Upton, NY 11973-5000 Environment Safety Health and Quality Directorate James Tarpinian, Assistant Laboratory Director Radiological Control Division Manager Quality Assurance Representative EMS Representative ESH&Q ESH/RCD Training/Work Control Coordinator Administrative Assistant Admin. Secretary HP-Technical Services Section Training RAP Facility Support Section Analytical Services Lab Rad Eng Personnel Monitoring Group BGRR Instrumentation & Calibration - Bioassay Program - TLD Program ESHQ&T - Records Management Radiological Control Division April 2003 Internal Dosimetry Personnel Manager, Personal R. Reciniello Monitoring Program QA Officer S. Sengupta Internal Dosimetrist C. Sun Internal Dosimetry L. Michel Assistant Summaries of Internal Dosimetry Program at Brookhaven (mSv/#) Year 2004 2003 2002 2001 Non-3H 3H Direct In-Direct Bioassay Bioassay Bioassay ~312 264 253 378 DAC-hr program (Positive) ~0.05/2 0/0 1.88/20 1.67/19 ~94 133 136 231 ~3 --60 2000 447 263 28 -- History of BNL TBD Revision 0 1A Effective Date May 5, 1999 September 12, 2000 2 3 4 --March 29, 2001 (March 2003) What is it ?   A program to assess intake of radionuclides and the resultant dose. A program to assess potential uptake of radionuclides and the resultant dose. Why ?  10CFR835.402 (c) Requirements  For the purpose of monitoring individual exposures to internal radiation, internal dosimetry programs (including routine bioassay programs) shall be conducted for:  Radiological workers who under typical conditions, are likely to receive a CEDE of 1 mSv or more from all occupational radionuclide intakes in one year… US Occupational Dose Limits. 10CFR835 or 10CFR20  Except for planned special exposures…, no person shall transfer, receive, possess or use any radiation source so as to cause any individual adult to receive an occupational dose from all sources of radiation that exceeds any of the following limits: (i) The annual limit, which is the more limiting of: (a) The TEDE being equal to 0.05 Sv; or (b) The sum of the deep dose equivalent and the CDE to any individual organ or tissue other than the lens of the eye being equal to 0.50 Sv. (ii) The annual limits to the lens of the eye, to the skin, and to the extremities which are: (a) An eye dose equivalent of 0.15 Sv, and (b) A shallow dose equivalent of 0.50 Sv to the skin or to any extremity. Total Effective Dose Equivalent  TEDE  The sum of the external dose equivalent and the committed effective dose equivalent (internal and external dose) The dose limit is 5 cSv per year.  Drivers for TBD  Internal Dosimetry Program Guide for use with Title 10 CFR, Part 835, Occupational Radiation Protection (DOE G 441.1-3: 0317-99) DOE STANDARDInternal Dosimetry, (DOE-STD-1121-03) DOE Laboratory Accreditation Program (DOELAP), DOE-STD-1112-98, 1998 DOELAP HPS/ANSI DOE-STD-1121 10 CFR 835   How to Bioassay?  Whole Body Count (Invivo)   Fission and Activation products Am-241?  Urine/Fecal sampling (In-vitro)        Tritium C-14, P-32 Sr/Y-90 Radium Uranium TRU Dosimetry Terms  Intake   The amount of radionuclide that is taken into the body through inhalation, ingestion, absorption through skin, or wounds. E.g., material that was inhaled or swallowed Dosimetry Terms  Uptake    The material that is reached in systemic blood or taken into the body organs. Eventually retain in the body or be eliminated via urine. By inhalation it is the material taken in (intake) minus the material that has been exhaled or By ingestion, the materials passed through the GI tract and excreted via feces. Retention Function 1 Fraction of intake Sr/Y-90 0.1 0.01 0.001 0 1 10 100 Days 1000 10000 100000 Dosimetry Terms (ICRP)  Effective Dose Equivalent  The sum over specified tissues of the products of the dose equivalent in a tissue (T) and the weighting factor for that tissue, (wT), i.e.,  HE =  (wTHT) = Hwb.  Committed Dose Equivalent  The dose delivered to an organ or tissue over a period of 50 years. This 50 year dose is assigned in the year of the intake Dosimetry Terms, EDE  Effective Dose Equivalent, EDE= wT × HT  HT = Organ CDE  wT = tissue weighting factor Relationship of Dose Assessment Terms  Uptake = f1 × Intake Effective Dose = Equivalent Dose   wT×  TEDE= CEDE + External Dose Technical Basis Document (TBD)  Tech Basis of Internal Dosimetry at BNL for how to:      Selection of participants Monitoring; baseline, termination, routine, and special Detection limits and interpretation Dose Assessment & Bioassay models Technological Shortfall Table of Contents (Main) 1 2 Introduction – Brookhaven National Laboratory (BNL). Objectives and Drivers- Descriptions of regulatory drivers and internal dosimetry program objectives. Organization and Agreements - Descriptions of organization in terms of functions and responsibilities. 3 4 5 Source Terms and Selection of Participants - Criteria for internal dosimetry monitoring. Assessing Intakes of Radionuclides - How individual intakes are estimated. Assessing Internal Radiation Doses - How the estimated intakes are interpreted to doses. 6 7 Follow-up Actions - Action plans and dose criteria, if so warranted. Records and Reports - BNL radiation dose reporting system. Documentation - Dose generated and control, the paperwork. 8 9 TOC (Appendix) A B C D E F G H I J Cross reference with DOE-STD-1121-98 Acronyms Definitions of terms Required contract laboratory specification Tritium monitoring and dose assessment Fission/activation product monitoring and dose assessment Iodine monitoring and dose assessment Strontium monitoring and dose assessment Uranium and transuranium monitoring and dose assessment Air monitoring (DAC-hr) and dose assessment BNL - Introduction  There are approximately 3,000 workers and 1,500 visitors or contractors at BNL each year.[1] Of these, approximately 300 per year are participants in the internal dosimetry program.  This TBD has a total of 9 chapters and 10 appendixes that provides the rationale for the BNL radiation protection and safety control program, which is defined as a composite of equipment, trained personnel, and procedures that are used to monitor personnel for intakes of radioactive material and maintain integrated exposure records. The TBD serves as BNL’s scientific basis of bioassay protocol, operational procedures, method of internal dose assessments, dose records and documentations, and related radiation monitoring and safety implementing guides. At BNL, workers include both employees and guest researchers.  [1] Consensus Standards                ICRP Publication 23, “Report of the Task Group on Reference Man” ICRP Publication 26, “Recommendations of the International Commission on Radiological Protection ICRP Publication 30, “Limits for Intakes of Radionuclides by Workers” ICRP Publication 48, “The Metabolism of Plutonium and Related Elements” ICRP Publication 54, “Individual Monitoring for Intakes of Radionuclides by Workers: Design and Interpretation” ICRP Publication 56, “Age Dependent Dose to Members of the Public from Intake of Radionuclides: Part 1.” ICRP Publication 60 “1990 Recommendations of the International Commission on Radiological Protection” ICRP Publication 66 “Human Respiratory Tract Model for Radiation protection.” ICRP Publication 67, “Age Dependent Dose to Members of the Public from Intake of Radionuclides: Part 2” NCRP Report No. 84, “General Concepts for the Dosimetry of Internally Deposited Radionuclides” NCRP Report No. 87, “Uses of Bioassay Procedures for Assessment of Internal Radionuclide Deposition” NUREG/CR-4884, “Interpretation of Bioassay Measurements” NUREG/CR-5631, “Contribution of Maternal Radionuclide Burdens to Prenatal Radiation Doses” EPA Federal Guidance Report No. 11, “Limiting Values of Radionuclide Intake and Air Concentration and Dose Conversion Factors for Inhalation, Submersion, and Ingestion” NUREG-1400, “Air Monitoring in the Work Place”            ANSI N10.4, “Verification and Validation of Scientific and Engineering Computer Programs for the Nuclear Industry”. ANSI/HPS N13.1, “Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stacks and Ducts of Nuclear Facilities” ANSI/HPS N13.6, “Practice for Occupational Radiation Exposure Records Systems” ANSI N42.17B, “Performance Specifications for Health Physics Instrumentation - Occupational Airborne Radioactivity Monitoring Instrumentation” HPS N13.14, “Internal Dosimetry Programs for Tritium Exposure Minimum Requirements” HPS N13.30, “Performance Criteria for Radiobioassay” HPS N13.42, “Internal Dosimetry for Mixed Fission and Activation Products” ANSI N42.23, "Measurement and Associated Instrumentation Quality Assurance for Radioassay Laboratories". ANSI N323, "American National Standard for Radiation Protection Instrumentation Test and Calibration". ANSI Z88.2, "American National Standard for Respiratory Protection". ANSI/HPS N13.39-2000, "Design of Internal Dosimetry Programs". TBD -- Agreements  Brookhaven Science Associates (BSA) operates the laboratory (BNL) for the US. DOE pursuant to Contract No. DE-ACO2-98CH10886. BSA's ability to achieve high ratings in its effectiveness of the Internal Dosimetry Program in which it is integrated into site-wide radiological health, monitoring, protection, and control activities. BNL relies upon the support services of both on-site and outside organizations or services to maintain its programmatic objective. MOU and SOW    Radiological Control Policy outlined in the 10 CFR835 (1999)    Radiation exposure of the work force and members of the public shall be controlled such that their radiation exposures are well below the national regulatory limits and that there is no exposure without commensurate benefit (JUSTIFICATION). All radiation exposures and intake shall be maintained as low as reasonably achievable, i.e., ALARA, (OPTIMIZATION). Individual doses are maintained below regulatory dose limits (DOSE LIMITS). A process of continual improvement is in workplaces monitoring and at the administration control to enhance the radiological safety and control program over time. Radiological Control Policy outlined in the 10 CFR835 (continue)  JUSTIFICATION, OPTIMIZATION, DOSE LIMITS.   Excellent performance is evident when below regulatory limits are maintained, radioactivity is safeguarded, radiological contamination and spills are prevented, and uncontrolled release is minimum, and, Each person involved in radiological work is expected to demonstrate responsibility and accountability through an informed, disciplined and cautious attitude toward handling radiation and radioactivity. Basis for BNL Radiological Control  ICRP radiological protection philosophy (justification, optimization, and dose limits) DOE STANDARD-Internal Dosimetry, (DOE-STD1121-98: May 2003) ANSI/HPS N13.39 “Design of Internal Dosimetry Program” ANSI/HPS N13.30 “Performance Criteria for Radiobioassay”    Criteria for Monitoring  Workers with the potential to incur intakes of radioactivity that may result in a CEDE in excess of 100 mrem. This requirement is necessary to comply with 10CFR835.402(c).  BNL also requires individuals with the potential to incur intakes resulting in a CDE in excess of 1,000 mrem to be monitored. Monitoring Types (Bioassay)  At BNL, there are several types of direct (in-vivo) and indirect (in-vitro) bioassay monitoring programs are:  Baseline  Termination  Routine  Special  Confirmatory Bioassay Implementation at BNL  Routine Bioassay (Initial & Termination)  Program to monitor those individuals that by their work assignments are potentially exposed to internal intakes of radioactive materials.  Those individuals that:  Routinely enter contamination areas  Wear respiratory protection for radionuclides Bioassay Implementation At BNL  Non Routine Bioassay Program  RWP Requirements (prejob & postjob)  Incidents:  Contamination  Suspected intake  Acute unexpected airborne activity  Special Bioassay Sampling Approach for Dose Determinations  All doses of record are determined by the methodology promulgated by the ICRP in Publications 26 and 30. The following internal radiation doses are assessed:  Committed Effective Dose Equivalent (CEDE) Committed Dose Equivalent (CDE) to tissues of concern Total Effective Dose Equivalent (TEDE) Cumulative Total Effective Dose Equivalent (CTEDE)   Quality Control Program (QC)  QC/QA applies to everything (i.e., sample preparation, radiochemistry, and dose assessment)  Manager periodically reviews mathematical function and data interpretation methods including error propagation. Independent auditing and review, V&V software and COC samples are used to enhance the program. BNL – SBMS, ISO-14001, PM-QAPs   Independent Review (QA)  A review and audit by a qualified individual other than the person responsible for the dose assessment is performed if the calculated dose exceeds the IL[1] V&V all Doses estimated using a person-specific approach by qualified individuals. During peer review, the assumptions and models used to derive the radiation dose must be evaluated, with mathematical derivations and the associated uncertainty, as necessary.   [1] U.S. DOE-STD-1112-98, “Department of Energy Laboratory Accreditation Program for Radiobioassay Programs”, Section 11.2, 1998. TBD Periodic Review (QC)   TBD review cycle is a 24-month maximum. TBD can be reviewed and implemented by members of the RCD who are knowledgeable of the topic, but not directly associated with day-to-day operation of the BNL program or an external reviewer who is an internal dosimetrist in the USDOE community [1] TBD must have a current scientific basis and appropriately reflect change in existing standards, anticipated change and new standards, and all routine internal dosimetry operations at BNL must be addressed.  [1] 10 CFR §835.102, “Internal Audits ”. Source Terms  BNL routine bioassay program for internal dose monitoring has been designed to meet both DOE and BNL objectives as they pertain to these categories. Further, each facility at BNL that uses radionuclides provides a "Source Term" document that includes, at the minimum, the following information:      Type radiation and quantity (annual amount) of each radioisotope in use How/when determined Physical and chemical forms) of the material (i.e., sealed, bulk material, gas) Schedule for re-evaluating isotopic ratios and inventory Bioassay requirement estimation calculation. (BNL Forms HP3120 and PM 6420) Source Term Assessment      Facility History Historical air sample data Smear Survey data Waste characterization data Resuspension factors Source Term Assessment Pre job Air Samples/Smear Samples Isotopic data  Alpha Counts  Beta Counts   What is the potential for airborne levels ?   SOP 4025, Laboratory Assessment Resuspension factors Source Term: An Example Nuclide Co-60 Sr-90 Pu-238 Pu-239 Pu-240 Pu-241 Am-241 Total Activity (Ci) 1.4E3 1.4E1 9.5E-3 7.1E–1 1.3E–1 3.7E–1 7.2E-2 ALI (uCi) 2,000 4 0.007 0.006 0.006 0.3 0.006 ALI Fraction 7E5 3E6 1E6 1E8 2E7 1E6 1E7 1.36E8 % 1.44 2.10 0.84 73 14 0.77 7.48 99.63 Ratio to AM-241 0.193 0.28 0.11 9.75 1.84 0.103 1.00 13.4 Resuspension Factors?   Method to assess the potential for surface radioactivity to produce airborne radioactivity Factors     1E-6 1E-5 1E-4 1E-3 No activity Walking moderate activity vigorous activity Tritium Source Term Description    A source of occupational exposure to tritium is in the magnet cooling water of the Alternating Gradient Synchrotron (AGS), where tritium is produced by spallation and neutron activation of the water, with concentrations ranging to 0.016 mCi per liter. Other sources of tritium include bulk inventories used for biological and medical research, in quantities that seldom exceeds 10,000 mCi in a year. Background sources are also present in drinking water (concentrations of 0.1 to 0.4 mCi/mL, and in commercially-manufactured devices (i.e., upper-scale watches, clocks, and exit signs). Fission & Activation Product Source Term Description  Currently, assorted biological, chemical and medical research using radioactive materials, environmental restoration programs, and waste management activities are underway. Each of the facilities where these operations occur is a potential source of fission or activation (corrosion) products.  There is a large spectrum of fission/activation products that may cause a significant internal dose. However, only a limited number of these are present in sufficient amounts to offer any dosimetric significance. For the activation products, it is the elements found in steel and alloys used in reactor components (i.e., cobalt, manganese, and iron). For fission products, the higher yield elements, such as cesium, strontium, iodine, and europium are the most predominant. Iodine Source Term Description  Personnel at the BNL may encounter isotopes of iodine during charcoal filter exchanges at reactor facilities. In addition, medical and biological research infrequently include the use of iodinated compounds. The typical isotopes of iodine found at the facility include I-131, I-125 and I-129, and to a lesser extent, I-133 and I-123.  Strontium Source Term Description  Sr-90/Y-90 exist at BNL wherever decommissioning activities are undertaken. Because of its 30-year radiological half-life, Sr-90 (with its Y-90 daughter in secular equilibrium) is now the strontium isotope of significance at BNL.  Areas that have strontium may be expected to have Cs-137, and it is common practice to use Cs-137 as an indicator of potential Sr-90. Daily dietary intake of Sr-90 estimated between 2.7 and 10.8 pCi d-1 according to UNSCEAR (1982). The concentration in milk is between 1.1 and 5.4 pCi L-1. These levels are attributed to worldwide fallout and natural variability.  U & TRU Source Term Description  TRU exist at the BNL in a variety of locations, thus the spectrum of radionuclides that may cause an internal dose of significance at BNL is large. However, only one (1) of these is present in sufficient amounts or offers any dosimetric significance. That radionuclide is Am-241. Also present, however, are Pu-238, Pu-239, U-235, and U-238. In many cases, Am-241 is used as the primary indicator of transuranic intake, and is thus used to demonstrate the methodology. The remaining transuranic elements are addressed similarly, with any deviations from what appears herein (i.e., those associated with half-life and/or chemical form differences) captured in the implementing procedures for the internal dosimetry program.  STANDARD OPERATING PROCEDURES -- Internal Dosimetry No. 17 DATE 10/10/02 Rev. 3 Title Evaluating & Reporting Tritium Doses 18 320 10/10/02 12/16/02 3 4 Non-Tritium in Vitro monitoring Maintenance of Liquid Nitrogen Supply to WBC Detectors 324 326 336 08/01/00 12/16/02 11/19/01 1 4 3 Detector Drive Adjustments and Safeguards QA: System Performance Verification and Trending Whole body Counting Service 338 340 342 344 11/19/01 12/16/02 2/24/03 04/15/02 5 5 3 1 Internal Dosimetry Recording and Reporting Protocols IN VIVO Monitoring: Whole Body Counts. Internal Dose Assessment Guidance Accuscan II Software & Data Management Operation 346 348 352 353 370 371 04/12/02 4/11/02 12/16/02 12/16/02 4/15/02 12/16/02 2 2 4 1 2 2 WBC Parameter Selection and Modification Accuscan II System (Hardware) Operations Accuscan II WBC System Calibration Operations Development of Accuscan II WBC Systems Control Charts In Vivo Monitoring Iodine Measurements using HPGe Detectors In Vivo Monitoring: Iodine-125 Measurements WBC Detection (nCi) at BNL Radionuclide Annihilation Be-7 Co-57 Co-58 KeV 511.00 477.59 122.06 810.76 MDA@ 2.46 22.2 2.44 3.23 Co-60 Cs-134 Cs-137 I-131 1332.49 604.70 661.65 364.48 3.65 3.08 4.77 3.47 Ce-139 K-40 @ November 21, 2003 165.85 1460.81 2.93 131.54 Technological Shortfall  Technological Shortfall  Where the normal means of monitoring is unable to detect a CEDE of 100 mrem  The MDA of the the method is greater than 100 mrem. Which is the 10CFR835 requirement.  Alternative or indirect methods of assessment are necessary  Such as source term ratios and DAC-hr tracking DAC-Hr Tracking Method    DAC= ALI/Annual Air Intake Breathing rate = 0.02 m3/min. 1 DAC-Hr of exposure = 2.5 mrem of CEDE based on 2,000h (50 weeks at 40 h per week) at “light” activity. DAC-Hr Action Levels Action Levels Mode DAC-h No tracking all* <1 Routine Bioassay acute  10 Timely Special bioassay all  40 Dose Assessment all  10 Contractor Discretion cumulative < 10 * Acute and cumulative within a calendar year.  10 means “equal” and “greater” TBD is a Living Document COMPLIANCE EFFECTIVENESS REVIEW