ML20246L344
| ML20246L344 | |
| Person / Time | |
|---|---|
| Issue date: | 05/09/1989 |
| From: | Remick F Advisory Committee on Reactor Safeguards |
| To: | Zech L NRC COMMISSION (OCM) |
| References | |
| ACRS-R-1357, NUDOCS 8905180298 | |
| Download: ML20246L344 (4) | |
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o, e,, p May 9, 1989 The Honorable Lando W. Zech, Jr.
Chairman U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Dear Chairman Zech:
SUBJECT:
GENERIC LETTER RELATED TO OCCUPATIONAL RADIATION EXPOSURE OF SKIN FROM HOT PARTICLES During the 349th meeting of the Advisory Committee on Reactor Safeguards, May 3-6, 1989, we reviewed the referenced draft generic letter, including a draft Interim Standard on Occupational Dose for Skin from Beta Radiation Emitted from a' Hot Particle. Our Subcommittee on Occupational and Environmental Protection Systems, its consultants, and invited expert Dr. Dade W. Moeller, discussed this matter during a meeting held on April 20,-1989 with represen-tatives of the NRC staff, the National Council on Radiation Protection and Measurements (NCRP), and the Nuclear Management and Resources Council (NUMARC). We also had the benefit of the documents referenced.
During the past few years, high sensitivity personnel contamination monitor-ing equipment has been installed in most nuclear power plants to improve their radiation protection programs. This has resulted in the occasional discovery of microscopic hot particles on workers' skin and clothing at many nuclear power plants. (Fragments from Stellite faced components containing cobalt-60 and irradiated fuel fragments are the most common hot particles.)
It is clear that hot particles have always been around nuclear power plants but generally were not detected. We have been told that there is no evidence that these hot particles have caused workers any adverse health effects. The staff has concluded that the existing 10 CFR Part 20 limits intended for I exposures of large areas of skin (7.5 rem per quarter for skin of the whole body and 18.75 rem per quarter for the extremities) are overly restrictive when highly localized exposure results from a hot particle. The staff plans to amend 10 CFR Part 20 to provide a less restrictive limit for exposure of the skin by hot particles. Until this amendment to 10 CFR Part 20 becomes effective, the staff proposes to use the interim standard, that is enclosed in draft form with the generic letter, in taking enforcement actions.
Industry representatives have been expressing concern since 1987 that, as a result of the current interpretation of the regulation, an unduly high level of attention and emphasis is being given to hot particle doses at nuclear power plants. These representatives have indicated that this situation is causing unnecessary fear and concern among nuclear power plant workers. We e
believe this to be a very serious issue. Industry has also provided data showing that workers could be exposed to substantially less whole-body ty$ sit $MS - ;q
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The Honorable Lando W. Zech, Jr. May 9, 1989 l
radiation (from sources other than hot particles) by setting a more realistic hot particle exposure limit. In order to avoid what the staff is considering as " overexposure" from hot particles, licensee radiation protection programs require that workers be monitored frequertly for hot particles during work in areas that have the potential for hot particle exposures. This more frequent monitoring increases the time workers spend in radiation areas to complete a given task and thus increases whole-body radiation exposures. The results of an industry survey reported by NUMARC indicate that implementation of a more realistic limit (discussed below) for hot particle exposure would result in ;
an estimated reduction in whole-body dose of 5 to 45 person-rem per year per nuclear power plant unit. (For 1987, the average total collective dose per unit was 420 person-rem.)
Other concerns expressed by industry are cost related (reduced worker pro-ductivity and the need for more health physics technicians), increased radwaste volume, impact on SALP ratings, and potential insurance and legal considerations.
Industry representatives have emphasized that a change in the NRC position would not result in a decrease in the protection of workers or the general public nor in the controls that have been established to prevent hot parti-cles from being transported off-site.
The staff, in March 1987, asked the National Council on Radiation Protection and Measurements (NCRP) to study the health significance of exposure from hot particles on the skin and to provide recommendations based on the findings of this study. (NCRP has an international reputation for excellence in the field of radiation protection and has been chartered by Congress to work with federal a matters.)gencies and NCRP A five-person otherssubcommittee in developing madeguidance this study,inand radiation the NCRPprotection provided a report entitled, " Recommendations on Limits of Exposure to ' Hot Particles' on the Skin" to the staff on June 17, 1988. This report was subsequently reviewed and approved by the full 75-member NCRP.
The NCRP recommendations are " based on ensuring that ulceration of minute areas of the skin" does not occur. The risk of radiation-induced skin cancer from exposure to a hot particle was not considered to be significant or controlling by NCRP. NCRP's recommended exposure limit for particles less than 1 mm in diameter is IE+10 beta particles emitted from the surface of the particle. (This limit is expressed as 75 microcurie-hours where one beta particleisemittedperdisintegration.) They recommend that any overexposed individual be previded with follow-up medical evaluation with respect to skin ulceration. Depending on particle size and isotopic composition, this results in a dose limit ranging from 300 to 800 rad. To place this dose in perspective, a 2000 rad dose is the accepted limit for radiotherapy treatment involving large areas of the skin. This limit is also based on avoiding skin ulceration.
In its June 17, 1988 transmittal letter, NCRP stated that its recommendations may be considered " firm" (subject to final editorial changes) and " ray be
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~ The Honorable Lando W. Zech, Jr. - Stay 9, 1989 used and quoted as appropriate." This letter indicated that the NCRP report would be published in final form in the fall of 1988. The staff subsequently raised a number of technical and philosophical questions with respect to the-NCRP recommendations that are currently in the process of being answered.
NCRP also requested that NUMARC provide comments on the NCRP report.
NUMARC's comments supported NCRP's approach to the hot particle problem but pointed out what NUMARC believed to be considerable conservatism used in the NCRP recommendations. - As a result of ~ the staff and NUMARC coments, there is no firm schedule for final publication of the NCRP report.
' The staff plans to revise appropriate sections of 10 CFR Part 20 to limit hot particle exposure of the skin and will consider the final NCRP recommenda-tions and recent research results. However, the staff recognizes that it will be at least two years- until this revision can become effective and believes that it is appropriate to use an interim standard in the exercise of its enforcement discretion regarding hot particle exposures.
The staff considered implementing the recommendations in the NCRP report in its interim standard for skin exposures to hot particles. However, the staff decided, for a variety of reasons cited in the draft generic letter, that it would be inappropriate to implement these NCRP recommendations at this time.
Instead, the interim standard enclosed with the draft generic letter, in effect, changes the limit for exposure of the skin to radiation from hot particles from 7.5 rem (skin of the whole body) or 18.75 rem (skin' of the hands and forearms, and feet and ankles) per calendar quarter to 50 rad per hot particle exposure.
Recommendations We do not endorse the staff's proposal to issue the generic letter and interim standard in its present form. Industry, in its presentation to us, has made a strong case that the proposed interim standard for hot particle exposure would provide very little relief in addressing the hot particle problem and believes that the interim standard should be based on the NCRP recommendations.
The staff, on the other hand, has obvious difficulty in basing an interim standard on an unpublished NCRP report. Accordingly, we recomend that staff senior management take an active role in effecting a timely resolution of remaining outstanding issues with NCRP so that its report may be published.
The staff should then develop on an expedited basis an interim standard based l on. the NCRP recommendations. Based on what we have been told, we believe that this interim standard could be completed by September 1989. To the extent the standard differs from the NRCP recommendations, the staff's reasons for such modifications should be clearly and completely documented.
Also, the staff concurrently should move ahead with its planned revision of 10 CFR Part 20 rulemaking on this subject.
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e The Honorable Lando W. Zech, Jr. May 9, 1989 There are two additional items concerning the draft generic letter and interim standard that we believe should be corrected in the final interim standard.
First, the draft interim standard fails to define a hot particle with respect to size for purposes of regulatory control. This is a very important issue, ,
since the size of the exposed area of skin is central to the determination as to whether the exposure limits for large areas of skin or hot particles o should be used. NCRP uses 1 millimeter as the maximum size that should be used in implementing its recommendations. We believe that this issue needs ?
to be clarified in the final version of the interim standard and in the planned revision of 10 CFR Part 20 on hot particles.
Second, we recommend that the regulatory concept contained in Section 4, Occupational Exposure Limit, of the draft interim standard be reconsidered.
The section states that the NRC will not issue a notice of violation (N0V) for a single hot particle exposure (less than the proposed limit) to an individual during a calendar quarter. It further states that the staff may issue an NOV if any individual is exposed to two or more hot particles during a single event or to hot particles in two or more separate events during a calendar quarter. This policy appears to be an unnecessary and complicating feature of the draft interim standard given the existing regulatory require-ments of 10 CFR Part 20.201, Surveys, which requires that licensees must perform " adequate surveys." It is also inconsistent with the staff's posi-tion that hot particle exposures are not to be added to skin dose for record-keeping purposes and are not themselves additive unless they occur in the same location on the skin.
We intend to follow the progress of the interim and final resolutions of this difficult and controversial issue and will provide you with further comments as appropriate.
Sincerel ,
/
/
Forrest J. Remick Chairman
References:
- 1. Letter dated February 9,1989 from J. H. Sniezek, Office of Nuclear Reactor Regulation, to E. L. Jordan, Committee to Review Generic Re-l quirements,
Subject:
Generic Letter and Interim Standard Concerning Hot Particle Exposures of Skin l 2. Letter dated June 17, 1988 from W. R. dey, National Council on Radiation Protection and Measurements, to R. E. Alexander, Office of Nuclear Regulatory Research, transmitting NCRP Report 80-1, " Recommendations on Limits of Exposure to ' Hot Particles' on the Skin" (draft of June 1988/Rev. 3)
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