ML19220B070
| ML19220B070 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/12/1978 |
| From: | Grimes B Office of Nuclear Reactor Regulation |
| To: | Allen P NORTH ANNA ENVIRONMENTAL COALITION |
| Shared Package | |
| ML14358A173 | List: |
| References | |
| NUDOCS 7904250266 | |
| Download: ML19220B070 (4) | |
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UNITED STATES fg,gg NUCLEAR REGULATORY COMMisSICN
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May 12,1978 Mrs. P. M. Allen North Anna Environmental Coalition 112 Hallmark North Briarcrest Gardens Hershey, Pennsy,1yania 17033
Dear Mrs. Allen:
I am writing in answer to your letter of March 29, 1978, which asks several questions regarding the neutron exposure issues raised by Mr. Glen W. Zimmer in his January 25, 1978 memorandum to Rocer Boyd.
I'm sure much of your concern was answered by the presentation of Mr. Seymour Block to the ACRS on April 7,1978, which I underr*and you attended. Mcwever, we will answer your questions in this letter as well.
There have been several meetincs amonc the NRC staff and several memoranda (enclosedl that summarize the staff interactions and the results of inquiries to Battelle Pacific Northwest Laboratory (BNWL) and to the HRC regional offices. These enclosures include (1) a re-view of the facts in the case in a memorandun from D. Eisenhut and R. Yollmer to L. Higcinbothan of March 6,1978, which asks the Of fice of Inspection and Enforcement to review reactor licensee neutron moni-toring programs and (2) a memorandum from E. G. Case to S. Levine of April 3,1978, requestino a research study on effectiveness of neutron dosimetry at operating reactors.
Mr. Block's April 7, 1978 presenta-tion before the ACRS indicated that there does not appear to be a significant neutron exposure problem at cperating reactors.
In response to your scecific questions, we are providing the following responses:
Question f What are the names of those reactors where eersonnel are
" receiving seme neutron exposure which heretofore has been unkncwn"? or is this a newly-known problem at all reactors (PUR's)?
Response
We are not aware of any scecific reactors wh'ere personnel are receiving neutron exoosures which heretofore have been unknown.
The Zimmer memorandum was based on linited tecn-nical data frca a yet uncompleted technical p. ogram. We have discussed this matter with Mr. Zimmer and otner involved 73 103 7 ?o %2 f d 2 f C
P-P. M. Allen 2
May 12, 1978 people (see Attacnment 1) and have concluded that personnel neutron monitoring inaccuracies (if any) are not significant concerns.
Standard techniques of personnel neutron monitoring recuire that neutron radiation measurements be made with neutron dose equivalent ratemeters prior to personnel entry into
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radiation areas where neutrons may be present.
Neutron radiation exposures are then controlled by health physics personnel by limiting occupancy time in these areas in ac-cordance with the dose limit requirements of the Code of Federal Regulation, Section 10 CFR 20.101. Addi ti onally,
personnel may wear passive monitoring devices in accordance with the recommendation of Regulatory Guide 3.14 to corroco-rate the radiation survey measurements.
Question 2 Since your receipt of tnis January 25 memo, what new meas-urement technioues have been instituted at the reactors in question to remecy the " inadequacy" described in the memo?
Response
No new measurement technicues have been instituted because, at present, the staff feels that they are not warranted.
Licen-sees are using state-of-the-art dosimetry, including neutron /
gamma, ratio techniques.
By the request of the March 6 memo-randum (Enclosure 1), NRC Office of Inspection and Enforcement will review neutron dosimetry programs at pcwer reactors, to further ascertain that the programs are in accordance with the aforementioned regulations and Regulatory Guidance. Ve ri fi ca-tion that current regulatory guidance is being folicwed will provide assurance that neutron exposures are being properly assessed by licensees.
Question 3 If new measurenent techniques have not yet been instituted, what measures are beine taken 30 orciect workers from pre-viously unknown neutron exoosure?
Response
The enclosure and answers to the above questions answer this question. We do not believe there are "previously unknown neutron exocsures" but several checks are being instituted to review existing programs and further research (Enclosure 2) will attempt to determine if guidance can be given that will lead to greater accuracy in neutron measurement.
Question 4 What assessment is being made of catentially inadecuate reactor shieldinc?
Response
Assessments of the adequacy of reactor shielding are made at several points in the desion and operation of a commercial power reactor. First, the reactor snielding designers per-form calculations to estimata the effectiveness of their 93-104
C.
Mrs. 7.' M. Allen
-3 May 12,1978 shield design. During the licensing review process, the NRC reviews the design and the radiation field estimates made by the designers. During start-up testing, extensive survey measurements are made of the reactor shielding to en-sure that radiation dose rates (neutron and gamma) are not above design excectations and these are controlled as neces-sary by adding shi'. _'ng or restricting access to those areas.
Question 5 Have the workers at risk frca neutron exposure been so noti-fied and allcwed a voice in their assignments?
If workers have not been infomed of catential neutron exoosure, the Coalition nerecy recuests tnat sucn notification ce mace.
Response
With respect to workers being infomed of potential neutron exposures, the Code of Federal Regulations, Title 10, Part 19.12 and Part 20.206, requires that all individuals be in-fomed that they are entering an area where they may be ex-posed to radiation, including neutron radiation, and be in-structed in safety precautions associated with radiation hazards. 10 CFR 20.202 requires that licensees supply per-sonnel monitoring equipment to specified individuals.
For personnel neutron monitoring, Regulatory Guide 8.14 "Per-sonnel Meutron Dosimeters" was developed *.o provide acceptable guidance to licensees where exposure to neutrons may occur.
All of the above sections of the regulations :re inspected for compliance by the Office of Inspection and Er.forcement and appropriate enforcement actions are taken as discrepancies are noted.
The risks from neutrons per unit dose equivalent (REM) are not different from the risks from gamma radiation for the same dose equivalent.
In either case, the permissible limit for occuoational radiation exposure is as described in the Code of Federal Regulations Section 10 CFR 20.101.
Data on actual neutron exposures, obtained from licensees wnen employees teminate, have shcwn that neutron dose is a small fraction of the radiation exposure received by nuclear power plant workers.
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Sin arely, p/n 4 m~
Brian K. Grines, Assistant Directcr for Engineering and Projects Division of Operating Reactors
Enclosures:
As stated M+
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