Radiation Protection Program Update: The Details. July 2010

Transcription

1 Radiation Protection Program Update: The Details July 2010

2 Update Topics 2 Changes mandated by Title 10, Code of Federal Regulations, Part 835, Occupational Radiation Protection (10 CFR 835) How changes affect your work / dose Resources Code of Federal Regulations Federal Registers Guidance Documents Additional improvements

3 References 3 10 CFR 835 new regulations ICRP 60/68 source documents that prompted most of the changes Federal Register, Vol. 72, No. 110 (Friday, June 8, 2007) amendments to 10 CFR 835 promulgated See discussion (changes made and why) Radiation Protection Programs Guide for Use with 10 CFR 835 Implementation Guide (G C)

4 Background 4 DOE adopted the system of radiation dosimetry recommended in ICRP Publication 60 in 2007 Allows us to assess and record radiation dose received by DOE workers in accordance with updated accepted methods

5 What Was Changed? 5 New dosimetric terminology based on ICRP 60/68 in place of ICRP 26/30 New ICRP 60 Tissue Weighting Factors in place of ICRP 26 Weighting Factors New ICRP 60 Radiation Weighting Factors in place of ICRP 26 Quality Factors Amendments to other parts of the regulations that changed as a result of adopting the ICRP 60 dosimetry system and the resultant ICRP 68 dose conversion factors

6 New Terms 6 Old Dosimetric Term Committed effective dose equivalent Committed dose equivalent Cumulative total effective dose equivalent Dose equivalent Effective dose equivalent Quality factor Weighting factor Total effective dose equivalent New Dosimetric Term Committed effective dose Committed equivalent dose Cumulative total effective dose Equivalent dose Effective dose Radiation weighting factor Tissue weighting factor Total effective dose Deleted Terms (not in ICRP 60/68) Replacement Terms (not added to definitions because meaning is clear) Depth in Tissue (cm) Deep dose equivalent Equivalent dose to the whole body Shallow dose Equivalent dose to the skin or an extremity equivalent Lens of the eye dose equivalent Equivalent dose to the lens of the eye 0.300

7 Definitions 7 Equivalent dose (H T ) - the product of average absorbed dose in a tissue or organ and a radiation weighting factor (W R ). For external dose, the equivalent dose to the whole body is assessed at a depth of 1 cm in tissue; the equivalent dose to the lens of the eye is assessed at a depth of 0.3 cm in tissue, and the equivalent dose to the extremity and skin is assessed at a depth of cm in tissue. Committed equivalent dose (H T,50 )- the equivalent dose received by a tissue or organ over a 50-year period after the intake of a radionuclide into the body. It does not include contributions from radiation sources external to the body. Committed effective dose (E 50 )- the sum of the committed equivalent doses to various tissues or organs in the body multiplied by the appropriate tissue weighting factor E 50 = ΣW T H T,50 + w Remainder H Remainder,50 Where W Remainder is the tissue weighting factor assigned to the remainder organs and tissues and H Remainder,50 is the committed equivalent dose to the remainder organs and tissues.

8 Definitions 8 Effective dose (E) The summation of the products of the equivalent dose received by specified tissues or organs of the body and the appropriate tissue weighting factor (W T ) E = Σ W T H T Includes the dose from radiation sources internal and/or external to the body. For purposes of compliance with this part, equivalent dose to the whole body may be used as effective dose for external exposures. Total effective dose (TED) The sum of the effective dose (for external exposures) and the committed effective dose. Cumulative total effective dose The sum of all total effective dose values recorded for an individual plus, for occupational exposures received before the implementation date of this amendment, the cumulative total effective dose equivalent (as defined in the November 4, 1998 amendment to this rule) values recorded for an individual, where available, for each year occupational dose was received, beginning January 1, 1989.

9 9 Q changes to W R Radiation Type Q W R Neutrons, energy < 10 kev 3 5 Neutrons, energy 10 kev to kev Neutrons, energy > 100 kev to 2 MeV Neutrons, energy > 2 MeV to MeV Neutrons, energy > 20 MeV 10 5 Neutrons, unknown energy Spectral data are sufficient to identify the energy of the neutrons Table titled Quality Factors for Neutrons (10 CFR 835 section 2(b)) Formula taken from ICRP 60., appendix A, paragraph A12.

10 10 Q changes to W R Radiation Type Q W R X-rays, gamma rays, positrons, electrons 1 (including tritium beta particles) Photons, electrons and muons, all energies 1 Protons and singly-charged particles of unknown energy with rest mass greater than one atomic unit 10 Protons, other than recoil protons, energy > 2 MeV 10 Alpha particles and multiple-charged particles (and particles of unknown charge) of unknown energy 20 Alpha particles, fission fragments, heavy nuclei 20

11 New Tissue Weighting Factors (W T ) 11 Tissue/Organ Weighting Factor Tissue Weighting Factor Gonads Red bone marrow Colon 0.12 Lungs Stomach 0.12 Bladder 0.05 Breast Liver 0.05 Esophagus 0.05 Thyroid Skin 0.01 Bone surface Remainder* Whole body

12 New Tissue Weighting Factors (W T ) 12 The remainder is treated differently: Remainder = the five other organs or tissues, excluding the skin and lens of the eye, with the highest dose (e.g., liver, kidney, spleen, thymus, adrenal, pancreas, stomach, small intestine, and upper large intestine) The weighting factor for each remaining organ or tissue is 0.06 Remainder = adrenals, brain, extrathoracic airways, small intestine, kidneys, muscle, pancreas, spleen, thymus, and uterus. The equivalent dose to the remainder tissues is normally calculated as the mass-weighted mean dose to the preceeding ten organs and tissues. In those cases in which the most highly irradiated remainder tissue or organ receives the highest equivalent dose of all the organs, a weighting factor of (half of remainder) is applied to that tissue or organ and (half of remainder) to the mass-weighted equivalent dose in the rest of the remainder tissues and organs to give the remainder equivalent dose.

13 Other Changes 13 Revised for consistency with ICRP 68 dose conversion factors and 5 μm default AMAD for particles: Appendix A (DAC values for inhalation) Appendix C (DAC values for immersion) Appendix E (sealed source accountability values and requirements for posting and labeling radioactive material) Clarify transportation exclusion Radioactive material transportation not performed by DOE / DOE contractor is excluded Posting and access control is not needed for radioactive material transportation performed by DOE / DOE contractor under continuous control or labeled per DOT Receipt monitoring is not required for onsite shipments which have been under continuous control Exclude material, equipment, and real property approved for release in accordance with DOE approved authorized limits HS-20 developing guidance

14 Other Changes 14 Lowers the maximum amount of radioactive material which need not be labeled to 0.1 Ci labeling threshold would otherwise be 16 Ci for tritium! Allows use of thresholds for recording internal occupational exposures less than 10 mrem per result less than monitoring threshold per year Establishes DAC default values for radionuclides not listed in the rule Non-alpha emitters with radioactive half-life greater than two hours 4 E 11 μci/ml Alpha emitters 2 E 13 μci/ml Appendix D not significantly changed

15 15 Full compliance required by July 9, 2010!!

16 References 16 Slides by Peter V. O Connell: 10 CFR 835 Amendment, Office of Health and Safety, U.S. Department of Energy. ISCORS Public Meeting, Washington, DC. October 1, 2008.

17 Additional RPP Changes 17 In addition to the updates needed to be in compliance with 10 CFR 835, additional updates improve the rigor and quality of the Radiation Protection Program. Changes include: Dosimeter storage racks Supplemental dosimetry Sealed source custodians and training

18 Personnel Dosimeters 18 Dosimeter Use Keep dosimeter away from all medical, dental, and airport radiation exposures Dosimeter Return Promptly return your dosimeter at the end of the wear period Dosimeter Storage Leave your dosimeter on your assigned rack at the end of the work day. If your work area does not have a rack contact your POC or Henry Tran at ext

19 Supplemental Dosimeter 19 Pocket ion chambers (PICs) are prohibited for supplemental dosimetry because of calibration requirements. Do not use a PIC when radiological controls specify the use of supplemental dosimetry (i.e. entering a high radiation area). 1. Return any PICs you have to RPD 2. Contact RPD at x4299 to request an electronic dosimeter as needed to monitor and record your dose

20 Sealed Source Training 20 Sealed source training is dependent on the radionuclide, activity, and exposure rates. The training requirements are listed in the table below. In addition, sealed source custodians must be appointed by their supervisor. This can be accomplished by completing a form memo and sending to RPD. Contact RPD x4299 for details. Source Exposure Rate Training required Dosimetry required > 5 30 cm RWT I Personnel Dosimeter > cm GERT Personnel Dosimeter < cm GERT N/A How this affects you If you are a sealed source custodian: Have your supervisor appoint you if you have not done so already. Brief users on the new training requirements when issuing sources. If you are a sealed source user: Check with your custodian or RPD to verify you have the appropriate training.

21 Radioactive Materials and Sources 21 Notify Radiation Protection at ext prior to bringing any radioactive material onsite such as 1. Naturally occurring radioactive material, including thorium welding rods and sand blasting media 2. Sealed sources 3. Radiation generating devices such as radiography units, x ray generators, and soil density gauges

22 Summary 22 Change New dosimetry terminology New radiation weighting factors New source accountability classifications New DAC Values Dosimeter use and return Dosimeter boards Supplemental dosimeters Sealed source training RAM Notification How it Affects You Your dose report will look different, but the values are still in mrem. Limits are unchanged. Only affects neutron dose reporting. Sealed source custodians and sealed source users will be notified of any classification or radiological control changes. Radiological controls remain unchanged. To encourage prompt return, reminders will be sent to any dosimeter wearer who has not returned their dosimeter within 15 days after the wear period ends. After 30 days their supervisor will be notified. Please leave your dosimeter on the dosimeter board in your area at the end of the work day. If supplemental dosimeter is required, contact RPD to obtain a new supplemental electronic dosimeter. Sealed source custodians and sealed source users need to verify they have appropriate training. Notify Radiation Protection at ext prior to bringing any radioactive material onsite.