[Federal Register Volume 66, Number 134 (Thursday, July 12, 2001)]
[Proposed Rules]
[Pages 36502-36509]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-17448]


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NUCLEAR REGULATORY COMMISSION

10 CFR PART 20

RIN 3150-AG25


Revision of the Skin Dose Limit

AGENCY: Nuclear Regulatory Commission.

ACTION: Proposed rule.

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SUMMARY: The Nuclear Regulatory Commission (NRC) is proposing to amend 
its regulations to delete a reference to averaging over 1 square 
centimeter from its definition of shallow-dose equivalent (SDE). In 
addition, the proposed rule would change the method of calculating SDEs 
by specifying that the assigned SDE must be the dose averaged over the 
10 square centimeters of skin receiving the highest exposure. A result 
of this rulemaking is to make the skin dose limit less restrictive when 
small areas of skin are irradiated and to address skin and extremity 
doses from all source geometries under a single limit. This change 
would permit measuring or calculating SDEs from discrete radioactive 
particles (DRPs) on or off the skin, from very small areas ( 1.0 square 
centimeters) of skin contamination, and from any other source of SDE by 
averaging the measured or calculated dose over the most highly exposed, 
contiguous 10 square centimeters for comparison to the skin dose limit 
of 50 rem (0.5 Sv).

DATES: Submit comments by September 25, 2001. Comments received after 
this date will be considered if it is practical to do so, but the 
Commission is able to

[[Page 36503]]

ensure consideration only for comments received on or before this date.

ADDRESSES: Submit comments to the Secretary, U.S. Nuclear Regulatory 
Commission, Washington, DC 20555-0001, ATTN: Rulemakings and 
Adjudications Staff. Deliver comments to 11555 Rockville Pike, 
Rockville, Maryland, between 7:30 a.m. and 4:15 p.m. on Federal 
workdays.
    You may also provide comments via the NRC's interactive rulemaking 
Website at http://ruleforum.llnl.gov. This site provides the capability 
to upload comments as files (any format) if your Web browser supports 
that function. For information about the interactive rulemaking 
Website, contact Ms. Carol Gallagher, (301) 415-5905 (e-mail: 
[email protected]).
    Certain documents related to this rulemaking, including comments 
received, may be examined in the NRC Public Document Room, 11555 
Rockville Pike, Rockville, Maryland. These same documents may be viewed 
and downloaded electronically via the rulemaking Website. The 
regulatory analysis and the environmental assessment may be accessed 
via the NRC's Agencywide Documents Access and Management System (ADAMS) 
on the internet at http://www.nrc.gov/NRC/ADAMS/index.html.
    Obtain single copies of the environmental assessment and the 
regulatory analysis from Alan K. Roecklein, Office of Nuclear Reactor 
Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 20555-
0001, telephone (301) 415-3883, e-mail: [email protected].

FOR FURTHER INFORMATION CONTACT: Alan K. Roecklein, Office of Nuclear 
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001, telephone (301) 415-3883, e-mail: [email protected].

SUPPLEMENTARY INFORMATION:

I. Background

    With the installation in the mid and late 1980s of very sensitive 
portal monitors, many nuclear power plants detected contamination of 
individuals and their clothing by small, usually microscopic, highly 
radioactive beta or beta-gamma emitting particles having relatively 
high specific activity. These particles, known as ``discrete 
radioactive particles'' (DRPs) and sometimes ``hot particles,'' most 
commonly contain 60Co or fission products. DRPs apparently 
become electrically charged as a result of radioactive decay and, 
therefore, tend to be fairly mobile. DRP movement in the workplace is 
unpredictable and thus worker contamination is difficult to control. A 
unique aspect of DRPs on or very near the skin is that very small 
amounts of tissue can be exposed to large, highly nonuniform doses. 
These intense localized irradiations may produce deterministic effects, 
such as reddening of the skin, transient breaks in the skin or necrosis 
of small areas of the skin.
    In the late 1990s, reports of DRP exposures by a materials licensee 
were made when workers were exposed to DRPs while manufacturing 
radiographic sources. In addition to the DRP concern, several events 
have occurred involving very small areas ( 1. 0 square centimeters) of 
skin contamination, primarily in the handling of solutions of highly 
concentrated radiopharmaceuticals. These contamination events produce 
relatively large doses to very small areas of skin, resulting in an 
insignificant health detriment. Under existing provisions in NRC 
regulations, several of these contamination events have resulted in 
overexposures, as well as enforcement actions, with the result that 
workers could not be assigned work in radiation areas for the balance 
of the year. The consequences of these overexposures were not 
commensurate with the actual health detriment.
    The principal stochastic risk associated with irradiation of the 
skin is non-melanoma skin cancer, that is, basal cell and squamous cell 
skin cancers. The risk of skin cancer following irradiation of the skin 
by DRPs, or from very small areas of contamination, is not comparable 
to irradiation of extended areas of the skin because of the very small 
number of cells involved and the greater potential for high local beta 
particle dose to kill cells rather than cause transformation to a 
precancerous stage. The Congressionally-chartered National Council on 
Radiation Protection and Measurements (NCRP) in Report No. 106, Limit 
for Exposure to ``Hot Particles'' on the Skin (1989), conservatively 
estimated the risk of skin cancer following a DRP dose of 50 rem (0.5 
Sv) to an area of 2 mm2 to be 7 x 10-7 
Gy-1 (7  x  10-9 rad-1), and the risk 
of skin cancer mortality to be about 1  x  10-9 
Gy-1 (1  x  10-11 rad-1). Because the 
risk of stochastic effects (i.e., cancer) from gamma and beta radiation 
from DRPs has been shown to be negligible for DRP exposures to the 
skin, induction of skin cancer is of less concern than the potential 
for deterministic effects.
    In 1991, the NRC revised 10 CFR part 20 and its occupational dose 
limit for the skin of the whole body to 50 rem (0.5 Sv) SDE per year to 
prevent deterministic effects (56 FR 23360; May 21, 1991) that might 
result from a lifetime exposure at the dose limit. This dose limit for 
the skin is in 10 CFR 20.1201(a)(2)(ii) and is intended to prevent 
damage to areas of the skin that are large relative to areas exposed by 
DRPs, on the skin, and that could compromise skin function or 
appearance. The NRC noted in that rulemaking that certain issues ``are 
being resolved in other rulemaking proceedings because of either their 
scope, complexity, or timing.'' One of the issues that was listed 
concerned limits and calculational procedures for dealing with the DRP 
issue. It was recognized that the current skin dose limit was overly 
conservative for DRP doses and SDE to very small areas of the skin. The 
final rule stated that there would be a rulemaking to set limits for 
skin irradiation by DRPs. This proposed amendment to Part 20 responds, 
in part, to that commitment.
    The existing Part 20 skin dose limit of 50 rem (0.5 Sv) averaged 
over 1 cm2 is intended to apply to a relatively uniform dose 
to a larger area of skin than that usually exposed by DRPs and was 
intended to prevent deterministic damage to the skin. Because this 
limit was considered by the NCRP to be overly conservative for DRPs on 
or very near the skin, the NRC announced an interim enforcement 
discretion policy in Information Notice (IN) 90-48, ``Enforcement 
Policy for Hot Particle Exposures'' (55 FR 31113, July 31, 1990), that 
addressed reporting and mitigation if a DRP dose exceeded the existing 
50 rem over 1 cm2 limit, and enforcement action for 
overexposures would be taken if the DRP beta emission exceeded 75 
Ci-hrs (300-500 rads). To avoid DRP doses greater than 50 rem 
(0.5 Sv) and the resulting reporting requirement, licensees monitor 
workers frequently during the work shift for DRP contamination. This 
results in additional external dose either to the workers, who incur 
additional exposure time in exiting and reentering the restricted area, 
or to the radiation protection staff, who must enter the restricted 
area to perform the monitoring.
    In 1988, the NRC contracted with Brookhaven National Laboratory 
(BNL) to study the health effects of DRPs on the skin and initiated a 
contract with the NCRP to develop guidance on controlling DRP doses. In 
NUREG/CR-6531, ``Effects of Radioactive Hot Particles on Pig Skin,'' 
June 1997, BNL provided data on the probability of producing breaks in 
the skin from irradiation of the skin by DRPs in contact with or near 
the skin and

[[Page 36504]]

demonstrated that these effects would not pose any serious health 
problems to workers. On the basis of the BNL data, and many other 
reported studies and similar experiments performed by the Electric 
Power Research Institute (EPRI) and reported on in EPRI TR-104781, 
``Skin Injuries From Discrete Radioactive Particles,'' (1994) the NCRP 
recommended in Report No. 130, ``Biological Effects and Exposure Limits 
for ``Hot-Particles,'' (1999) a dose-limiting guideline for DRPs of 50 
rads (0.5 Gy) averaged over the most highly exposed 10 square 
centimeters. The BNL work only examined the nonuniform, highly 
concentrated dose to 1 square centimeter from DRPs in contact with or 
near the skin and not the dose that would be delivered to the adjacent 
skin tissue.
    In October 1998, the NRC staff submitted a rulemaking plan (SECY-
98-245) entitled ``Protection Against Discrete Radioactive Particle 
(DRP) Exposures (10 CFR part 20).'' The NRC staff proposed establishing 
a constraint of 300 rads (3 Gy) over 1 cm2 as a program 
design guideline or action level, and a limit of 1000 rads (10 Gy) per 
1 cm2 for DRPs on or near the skin. The existing skin dose 
limit would have been retained for all other skin doses. The intent of 
that proposed amendment was to reduce the additional external dose 
incurred by workers in monitoring for DRPs during work shifts and to 
reduce unnecessary regulatory burden by adopting more realistic 
thresholds for DRP dose control and reporting requirements. In a staff 
requirements memorandum (SRM) dated December 23, 1998, the Commission 
directed the NRC staff to proceed with rulemaking as proposed, but to 
use 500 rads (5 Gy) per 1 cm2 as the dose limit to be 
consistent with the NCRP recommendations in NCRP Report No. 106.
    In March 1999, several industry experts who had reviewed the 
publicly available rulemaking plan and SRM suggested that the planned 
action would not accomplish one of the intended objectives of the 
proposed rulemaking, that is, to reduce the frequency of worker 
monitoring. The following industry concerns were raised arguing against 
use of a DRP dose constraint with a 500-rem (5.0 Sv) limit and 
supporting use of the NCRP recommended skin dose limit that is proposed 
in this rule: Of all DRP events, fewer than 10 percent are on, or near 
enough to, the skin for the proposed constraint and limit to apply. 
Most DRP events (>90 percent) are DRPs on clothing, on hair, or are far 
enough away from the skin (and most likely moving) so that the dose to 
the skin is more uniform and is spread over a larger area. In that case 
the existing 50-rem (0.5 Sv) skin dose limit would be applicable. This 
information suggested that a reduction in DRP monitoring frequency, and 
the associated external dose, could not be realized for most DRP 
exposures, because of the need to prevent exceeding the existing skin 
dose limit. Because the licensee may not know in advance whether the 
DRP is on the skin or moving the licensee would need to assume that the 
existing skin dose limit was applicable.
    The justification for proposing a constraint, or action level, of 
300 rads (3.0 Gy) over 1 cm2 was in large part to reduce the 
additional external dose incurred by plant staff from frequent 
monitoring to avoid having to report a DRP dose that exceeded the 
existing 50-rem (0.5 Sv) skin dose limit. If more than 90 percent of 
DRPs are off the skin and irradiating a relatively large area, the 
existing skin dose limit would be controlling and the constraint would 
only rarely be used. The NRC staff concluded that little relief from 
monitoring dose would result from implementing the constraint and the 
500 rad (5 Gy) limit. In a memorandum to the Commission dated October 
27, 1999 (COMSECY-00-0009) the staff explained why the constraint with 
a limit of 500 rads (5 Gy) would not accomplish this intended 
objective, and recommended further staff work to identify an effective 
regulatory approach. In an SRM dated March 16, 2000, the Commission 
directed the staff to contract with the NCRP to provide additional 
technical support on this issue.
    In December 1999, the NCRP had published Report No. 130, 
``Biological Effects and Exposure Limits for ``Hot Particles.'' The 
NCRP recommended that the dose to skin at a depth of 70  (7 
mg/cm2) from hot particles on skin (including the ear), 
hair, or clothing be limited to no more than 50 rads (0.5 Gy) averaged 
over the most highly exposed 10 cm2 of skin.
    The averaging area of 10 cm2, recommended by the NCRP, 
would permit treating both the case when a DRP is on the skin or a very 
small area of skin is contaminated, and the case when a DRP is on 
clothing and moving about exposing an area on the order of 10 
cm2 or more. In the former case, averaging the very 
localized dose over 10 cm2 results in a dose value that more 
appropriately reflects the risk associated with a small area exposure. 
In the latter case, averaging relatively uniform dose to the entire 10 
cm2, results in an dose limit that is equivalent to the 
current 50 rem over 1 cm2. Thus the limit decreases as the 
exposed skin area increases to 10 cm2, consistent with the 
expectation that the risk of an effect increases with increasing area 
of skin exposed to a given dose level. This averaging area is also 
consistent with the skin dose limiting system adopted by the Department 
of Energy in 10 CFR part 835.
    In an effort to find the least burdensome regulatory requirement 
for controlling DRP doses, as well as other skin doses, while 
maintaining an adequate level of worker protection, the NRC staff 
requested the NCRP to consider the advisability of applying its 
proposed limit for DRP exposures to all skin dose geometries. In March 
2001, the NCRP published Statement No. 9, ``Extension of the Skin 
Exposure Limit for Hot Particles to Other Sources of Skin 
Irradiation.'' The statement can be found on the NCRP website at 
www.ncrp.com/statemnt.html. In this statement, the NCRP recommended 
that the absorbed radiation dose to skin at a depth of 70 m (7 
mg/cm2) from any source of irradiation be limited to 50 rads 
(0.5 Gy) averaged over the most highly exposed 10 cm2 of 
skin.
    Dr. John Baum, Ph.D., an NRC consultant, reviewed the health 
effects implications of the NCRP recommendation. Dr. Baum wrote a 
technical paper that was published in the June 2001 issue (pp. 537-543) 
of the peer-reviewed journal, Health Physics, entitled ``Analysis of 
Potential Radiobiological Effects Related to a Unified Skin Dose 
Limit.'' In this paper, the probabilities and severity of both 
stochastic and deterministic risks were estimated by Dr. Baum for a 
wide range of exposure scenarios based on the research done at 
Brookhaven National Laboratory, at other research facilities, and on 
additional information found in NCRP Reports Nos. 106 and 130. 
Published data from experimental and epidemiological studies, as well 
as calculations of radial-and depth-dose distributions, show that skin 
exposures at the dose limit of 50 rem (0.5 Sv) of SDE averaged over 10 
cm2 could result in stochastic risks of 3.3  x  
10-7 fatal skin cancers and 1.6  x  10-4 nonfatal 
skin cancers, confirming that stochastic risks at the proposed limit 
are small.
    Given exposures at the proposed skin dose limit, i.e., 50 rem (0.5 
Sv) averaged over 10 square centimeters, the worst case deterministic 
effects were estimated by Dr. Baum to be a 5 percent probability of 
erythema if all of the dose (500 rem) were delivered to an area of 2.5 
cm2, and a 50 percent probability that measurable dermal 
thinning would be observable if all of the dose were delivered to an 
area 0.5 cm2. At this

[[Page 36505]]

dose, no acute cell killing or skin ulceration was predicted for DRPs 3 
or more mm off of the skin because the dose is distributed over too 
large an area. The worst case probability of producing a barely 
detectable scab due to acute cell killing was estimated at 10 percent 
for 60Co or activated fuel DRPs located about 0.4 mm off the 
skin. A copy of this copyrighted article is available for viewing 
during the public comment period for this rulemaking at NRC's Public 
Document Room located in Rockville, MD.
    Additional discussion of implications of the health effects 
associated with the proposed unified skin dose limit can be found in 
the regulatory analysis developed for this rulemaking.

II. Summary and Discussion of the Proposed Changes

    The Commission is proposing to amend Sec. 20.1003, 
Sec. 20.1201(a)(2)(ii), and Sec. 20.1201(c).

Section 20.1003--Definitions

    In Sec. 20.1003 Definitions, the definition of shallow-dose 
equivalent would be revised to delete the words ``averaged over an area 
of 1 square centimeter.'' The purpose of these words was to specify the 
area over which the dose to the skin was to be measured or calculated 
for comparison to the limit. The proposed revision to permit averaging 
over 10 square centimeters for measuring and recording SDE would be 
found in Sec. 20.1201(c), along with other procedural requirements.

Section 20.1201--Occupational Dose Limits for Adults

    Section 20.1201, Occupational Dose Limits for Adults, would be 
changed in two places. Section 20.1201(a)(2)(ii) would be changed to 
make it clear that the SDE limit of 50 rem (0.5 Sv) is the dose limit 
to the skin of any extremity as well as the skin of the whole body. The 
Commission believes that this specification makes it clear that the 
only dose limit for the extremities is a SDE limit on the dose 
delivered at a depth of 0.007 cm (7 mg/cm2), not a deep dose 
limit.
    Section 20.1201(c) would be amended to specify that the assigned 
SDE must be the dose averaged over the 10 contiguous square centimeters 
of skin receiving the highest exposure. This is the significant change 
proposed in this rulemaking.
    Note that the NCRP made recommendations regarding limiting dose 
from DRPs in the ear and on the eye. The NRC staff believes that these 
are special cases only with respect to measuring or calculating the 
dose, and that the proposed skin dose limit, and the existing limit for 
dose to the lens of the eye, are adequate to control DRP doses to these 
areas.
    It is also important to note that it had been considered relevant 
to distinguish between doses from DRPs that were on or off the skin. 
With the proposed rule, this distinction is only relevant to dosimetric 
consideration, and the proposed limit is independent of source or 
exposure geometry.
    The NRC staff has elected to retain the units rem and Sievert for 
the skin dose limit. According to data published in reports of the 
International Commission on Radiation Protection, the unit for dose 
equivalent, rem (Sv) is acceptable for deterministic effects, 
especially at lower doses. The highest Relative Biological 
Effectiveness (RBE) values for deterministic effects in the skin are 
all less than the Q values, or dose weighting factors that are used to 
convert dose in rads (Gy) to dose equivalent in rem (Sv). The use of 
dose equivalent in units of rem (Sv) would be conservative and would 
have the advantage that all of the dose limits would be in the same 
units. The Department of Energy, in its regulations, uses the rem and 
Sievert for SDE.
    NCRP Statement No. 9 referred to NCRP Report No. 130 (NCRP 1999) 
for guidance on good practices, and recommended that in addition to 
numerical limits, observation of the exposed area of skin should be 
performed for four to six weeks whenever the DRP dose at a depth of 70 
m exceeds 10 rads (0.1 Gy) averaged over the most highly 
exposed 10 cm2 of skin. The observational level of 0.1 Gy is 
well below the proposed limit of 0.5 Gy, and is essentially equivalent 
to the current skin dose limit, at which no clinically significant 
effects have ever been reported. For those reasons the NRC is not 
proposing to incorporate the NCRP recommendation into the proposed 
rule.
    The objective of the rulemaking is to establish a uniform, risk-
informed skin dose limit for all sources of SDE, including DRPs, and 
small area contamination that: trades a higher risk of occurrence of 
deterministic effects to the skin for a reduction in the risk of whole-
body stochastic effects; allows licensees to reduce whole-body 
exposures and nonradiological health risks such as heat stress to 
workers subject to unnecessary DRP monitoring; and provides a common 
limit for SDE from all external sources of ionizing radiation. The 
proposed rule also reduces the unnecessary regulatory burden on 
licensees for reporting skin exposures that have insignificant health 
implications.
    The current statement of the skin and extremity dose limit, along 
with the current definition of SDE, requires that skin doses be 
averaged over 1 square centimeter. The proposed rule would permit 
averaging the SDEs delivered to the 10 most highly exposed, and 
contiguous, square centimeters. It is important to discuss the 
consequences of this proposed change in the context of different source 
geometries.
    In the case of large-area exposures of the skin from surface 
contamination or other external sources, areas on the order of 10 
square centimeters or more would be likely to receive a relatively 
uniform dose. There is little difference to be expected in recorded 
doses from the current requirement that would attempt to identify the 
most highly exposed 1 square centimeter and the new approach that would 
sum the SDE to the 10 highest-exposed, adjacent square centimeters and 
divide by 10. The recorded doses would be identical for the large-area 
(10 square centimeters or more) exposures that form the great majority 
of skin dose events.
    Under the proposed rule, exposed areas of the skin less than 10 
square centimeters would be treated in a less restrictive manner. For 
example, a dose of 250 rem (2.5 Sv) to each of 2 square centimeters 
would result in a 50-rem (0.5 Sv) SDE when averaged over 10 square 
centimeters. A dose as high as 500 rem (5.0 Sv) would be permitted to 1 
square centimeter and would be recorded as 50 rem (0.5 Sv) when 
averaged over 10 square centimeters. This change would effectively 
permit higher doses to small areas of skin than currently permitted by 
regulations.
    Although, as previously noted, the Commission is proposing a skin 
dose limit that in some source geometries is likely to permit more 
frequent occurrence of observable though transient deterministic 
effects, it is expected that the less restrictive limit would permit a 
reduction in the conservative use of protective clothing and other 
devices intended to prevent contamination and skin doses. As a result, 
workers should experience reduced exposure to nonradiological health 
hazards such as heat stress, and be subject to fewer industrial 
accidents caused by impaired motion. By reducing the overly 
conservative use of protective equipment, work should be performed more 
efficiently. Reduced time in the restricted area is expected along with 
a concomitant reduction in whole-body dose and stochastic risks. The 
Commission intends this change to lead to a reduction in overly 
conservative

[[Page 36506]]

efforts to prevent skin contaminations, that will result in decreased 
stress and lower whole-body doses. Numerous studies of the impacts on 
worker efficiency and safety resulting from the use of protective 
clothing and equipment have been published in the journal, Health 
Physics, in Radiation Protection Management, and by the Electric Power 
Research Institute (EPRI). A recent discussion of this issue and 
specific references can be found in NUREG/CR-0041, ``Manual of 
Respiratory Protection Against Airborne Radioactive Material,'' January 
2001.
    A final geometry of interest is the case of DRPs on or very near 
the skin, such that a relatively small volume of tissue receives a 
large dose, resulting in cell killing and possible observable breaks in 
the skin. Under the current dose limit a DRP could deliver 50 rem (0.5 
Sv) to an area of 1 square centimeter that when averaged over 1 square 
centimeter would yield a recorded dose of 50 rem (0.5 Sv). Under the 
proposed rule, the NCRP recommended limit, a dose of 500 rem (5.0 Sv) 
delivered to 1 square centimeter, when averaged over 10 square 
centimeters, would yield a recorded dose of 50 rem (0.5 Sv). Thus, for 
DRPs on the skin, and other small area exposures, the proposed rule 
change is in effect a tenfold relaxation of the current limit and might 
permit some increased number of observable, transient deterministic 
effects to the skin. This new limit would be approximately equivalent 
to the emission criterion of 75 Ci-hr in the interim 
enforcement policy stated in IN 90-48. The 500 rem (5.0 Sv) to 1 square 
centimeter (worst) case is estimated to result in a 50 percent chance 
of an observable but transient effect. NRC records include only one DRP 
dose that was calculated to exceed 500 rem (5.0 Sv), and no effects 
were observed in that case.
    On the basis of extensive research performed at BNL and elsewhere, 
the NCRP stated in Report No. 130 that ``if exposures are maintained 
below the recommended limits, few, if any, deterministic biological 
effects are expected to be observed, and those effects would be 
transient in nature. If effects from a hot-particle exposure are 
observed, the result is an easily treated medical condition involving 
an extraordinarily small stochastic risk. Such occurrences would be 
indicative of the need for improvement in radiation protection 
practices, but should not be compared in seriousness to exceeding 
whole-body exposure limits.''
    Reactor licensees are currently monitoring workers frequently 
during each work shift to prevent exceeding the interim 50-rem (0.5 Sv) 
reporting threshold for doses from DRPs. Industry estimated that up to 
5 person-rem (0.05 person-Sv) of whole-body dose per outage could be 
attributed to this monitoring. Workers are either brought out of the 
workplace to be monitored, incurring nonproductive exit-entry dose, or 
technicians enter the restricted area to monitor workers for DRPs. The 
proposed, less restrictive, skin dose limit would eliminate the need to 
perform this DRP monitoring during work shifts for all but the highest 
activity DRPs\1\, especially those having a high gamma component. The 
possibility of some additional number of observable deterministic 
effects, such as a small break in the skin, is considered by the NRC to 
be justified by the reduction of the whole-body dose and associated 
stochastic risks from monitoring for DRPs.
---------------------------------------------------------------------------

    \1\ For example, one recent event at a nuclear power plant 
involved a CO-60 DRP with an activity of about 75 mCi. The deep-dose 
equivalent estimated from this particle (had it been on the skin) 
was calculated to be about 10 rem/hr per mCi. For particles in this 
activity range, the deep-dose equivalent (DDE) limit of 5 rem per 
year can be exceeded in less than 1 minute. The proposed skin dose 
limit could be exceeded in even less time.
---------------------------------------------------------------------------

    The Radiation Exposure Information Reporting System (REIRS) 
database includes reports of nearly 15,000 individual DRP doses since 
1990. Fewer than 10 have exceeded the current 50-rem (0.5 Sv) reporting 
limit. It is unlikely that this proposed revision of the skin dose 
limit will result in any large increase in the number of DRP doses. The 
as-low-as-is-reasonably-achievable (ALARA) principle will continue to 
apply to any occupational doses, so the revised skin dose limit should 
not permit a large number of high DRP doses. It would be unacceptable 
for a licensee to permit large numbers of high DRP exposures on a 
continuing basis without attempting some mitigating procedures or 
engineering controls.
    The Commission believes that the less restrictive limit on skin 
dose to small areas that might permit more observable, transient, 
deterministic effects will also result in a less hazardous workplace 
and reduced whole-body occupational dose. The Commission considers this 
tradeoff to represent a substantial increase in worker protection. This 
represents a shift in emphasis toward a risk-informed approach that 
would possibly permit more frequent deterministic effects in order to 
avoid the physical stress and whole-body doses associated with 
monitoring workers and the use of protective measures. The NRC is 
specifically soliciting comments on the acceptability of this approach.

III. Issue of Compatibility for Agreement States

    Under the ``Policy Statement on Adequacy and Compatibility of 
Agreement State Programs'', which became effective on September 3, 1997 
(62 FR 46517), NRC program elements, including regulations, are 
assigned compatibility categories. In addition, NRC program elements 
can also be identified as having particular health and safety 
significance or as being reserved solely to the NRC.
    Compatibility Category A includes those program elements that are 
basic radiation protection standards and scientific terms and 
definitions that are necessary to understand radiation protection 
concepts. An Agreement State should adopt Category A program elements 
in an essentially identical manner in order to provide uniformity in 
the regulation of agreement material on a nationwide basis.
    Compatibility Category B includes those program elements that apply 
to activities that have direct and significant effects in multiple 
jurisdictions. An Agreement State should adopt Category B program 
elements in an essentially identical manner.
    Compatibility Category C includes those program elements that do 
not meet the criteria of Category A or B but represent essential 
objectives that an Agreement State should adopt to avoid conflict, 
duplication, gaps, or other conditions that would jeopardize an orderly 
pattern in the regulation of agreement material on a nationwide basis. 
An Agreement State should adopt the essential objectives of the 
Category C program elements.
    Compatibility Category D includes those program elements that do 
not meet any of the criteria of Category A, B, or C above and, thus, do 
not need to be adopted by Agreement States for purposes of 
compatibility.
    Health and Safety (H&S) includes program elements that are not 
required for compatibility (i.e., Category D) but that have been 
identified as having a particular health and safety role (i.e., 
adequacy) in the regulation of agreement material within the State. 
Although not required for compatibility, the State should adopt program 
elements in this category that embody the essential objectives of the 
NRC program elements because of particular health and safety 
considerations.
    Compatibility Category NRC includes those program elements that 
address

[[Page 36507]]

areas of regulation that cannot be relinquished to Agreement States 
pursuant to the Atomic Energy Act (AEA) or provisions of Title 10 of 
the Code of Federal Regulations. These program elements should not be 
adopted by Agreement States.
    The proposed modifications to Secs. 20.1003 and 20.1201, which 
contain definitions and basic radiation protection standards that are 
necessary to understand radiation protection concepts, are designated 
as compatibility Category A. Therefore, the Agreement State program 
element should be essentially identical to NRC's in order to provide 
uniformity in skin dose determinations on a nationwide basis.
    These proposed amendments were provided to the Agreement States via 
the NRC Technical Conferencing Forum. As of 5/24/01, only one comment 
had been received from the States.

IV. Plain Language

    The Presidential memorandum dated June 1, 1998, entitled ``Plain 
Language in Government Writing'' directed that the Government's writing 
be in plain language. This memorandum was published on June 10, 1998 
(63 FR 31883). The NRC requests comments on the proposed rule 
specifically with respect to the clarity and effectiveness of the 
language used. Comments should be sent to the address listed under the 
ADDRESSES heading of the preamble.

V. Voluntary Consensus Standards

    The National Technology Transfer and Advancement Act of 1995, Pub. 
L. 104-113, requires that Federal agencies use technical standards that 
are developed or adopted by voluntary consensus standards bodies unless 
using such a standard is inconsistent with applicable law or is 
otherwise impractical. In this proposed rule, the NRC is modifying its 
definition of Shallow-dose equivalent. This action does not constitute 
the establishment of a standard that contains generally applicable 
requirements.

VI. Environmental Assessment: Finding of No Significant 
Environmental Impact: Availability

    The NRC has determined under the National Environmental Policy Act 
of 1969, as amended, and the Commission's regulations in subpart A of 
10 CFR part 51 that this rule, if adopted, would not be a major Federal 
action significantly affecting the quality of the human environment 
and, therefore, an environmental impact statement is not required.
    An environmental assessment has determined that the proposed 
amendment addresses technical and procedural improvements in the 
provisions for determining by measurement or by calculation the dose to 
the skin for comparison to the skin dose limit for the whole body or 
for the extremities. None of the impacts associated with this 
rulemaking have any effect on any places or entities outside of a 
licensed site. An effect of this proposed rulemaking is expected to be 
a decrease in the use of protective equipment used by nuclear power 
plant workers and others potentially exposed to skin contamination, to 
prevent the skin contaminations. No changes are expected in licensee 
programs and procedures designed to mitigate the production and spread 
of DRPs in the workplace and to prevent the unauthorized release of 
radioactive materials off site. It is expected that there would be no 
change in radiation dose to any member of the public as a result of the 
revised regulation. The proposed amendment is expected to result in a 
reduction in external occupational dose to workers onsite.
    The determination of this environmental assessment is that there 
will be no significant offsite impact to the public from this action. 
However, the general public should note that the NRC is seeking public 
participation. The NRC has also committed to complying with Executive 
Order (E.O.) 12898, ``Federal Actions to Address Environmental Justice 
in Minority Populations and Low-Income populations,'' dated February 
11, 1994. The NRC evaluated environmental justice for this 
environmental assessment and has determined that there are no 
disproportionate high and adverse impacts on minority and low-income 
populations. In the letter and spirit of E.O. 12898, the NRC is 
requesting public comment on any environmental justice considerations 
or questions that the public thinks may be related to this proposed 
rule but somehow were not addressed. E.O. 12898 describes environmental 
justice as ``identifying and addressing, as appropriate, 
disproportionately high and adverse human health or environmental 
effects of its programs, policies, and activities on minority 
populations and low-income populations.'' Comments on any aspect of the 
environmental assessment, including environmental justice, may be 
submitted to the NRC as indicated under the ADDRESSES heading.
    The NRC has sent a copy of the environmental assessment and this 
proposed rule to every State Liaison Officer and requested their 
comments on the environmental assessment.
    The draft environmental assessment is available for inspection at 
the NRC's Public Document Room, One White Flint North, 11555 Rockville 
Pike (first floor), Rockville, Maryland. Single copies of this document 
are available as indicated in the ADDRESSES heading.

VII. Paperwork Reduction Act Statement

    This proposed rule would decrease the burden on licensees reporting 
under
    Section 20.2202(b)(iii) on DRP and other small area skin 
overexposures. The public burden for this information collection is 
estimated to average 40 hours per request. Fewer than 10 reports have 
been received by the NRC over the past 12 years. Because the burden for 
this information collection is insignificant, Office of Management and 
Budget (OMB) clearance is not required. Existing requirements were 
approved by the OMB, approval number 3150-0114.

Public Protection Notification

    If a means used to impose an information collection does not 
display a currently valid OMB control number, the NRC may not conduct 
or sponsor, and a person is not required to respond to, the information 
collection.

VIII. Regulatory Analysis

    The NRC has prepared a regulatory analysis for the proposed 
amendment. The analysis examines the benefits and impacts considered by 
the NRC. The regulatory analysis is available for inspection in the NRC 
Public Document Room, One White Flint North, 11555 Rockville Pike 
(first floor), Rockville, Maryland. Single copies of the analysis are 
available as indicated in the ADDRESSES heading.
    The Commission requests public comment on the analysis. Comments on 
the analysis may be submitted to the NRC as indicated under the 
ADDRESSES heading.

IX. Regulatory Flexibility Certification

    As required by the Regulatory Flexibility Act of 1980, 5 U.S.C. 
605(b), the NRC certifies that, if adopted, this proposed rule would 
not have a significant economic impact on a substantial number of small 
entities. The anticipated impact of the proposed changes would not be 
significant because the revised regulation basically represents a 
continuation of current practice. The benefit of the proposed rule is 
that it would permit averaging doses to the skin over the most highly 
exposed 10 square centimeters, incorporate an NCRP recommendation

[[Page 36508]]

for a less restrictive skin dose limiting procedure, and permit reduced 
use of protective equipment known to expose workers to workplace 
stresses and unnecessary whole-body radiation dose.
    The NRC is seeking public comment on the initial regulatory 
flexibility certification. The NRC is seeking comment particularly from 
small entities as defined under the NRC's size standards in 10 CFR 
2.810 as to how the proposed regulations would affect them and how the 
regulations may be implemented or otherwise modified to impose less 
stringent requirements on small entities while still adequately 
protecting the public health and safety. Any small entity subject to 
this regulation that determines that because of its size it is likely 
to bear a disproportionate adverse economic impact should offer 
comments that specifically discuss the following items:
    (a) The licensee's size and how the proposed regulation would 
result in a significant economic burden or whether the resources 
necessary to implement this amendment could be more effectively used in 
other ways to optimize public health and safety, as compared to the 
economic burden on a larger licensee;
    (b) How the proposed regulation could be modified to take into 
account the licensees' differing needs or capabilities;
    (c) The benefits that would accrue, or the detriments that would be 
avoided, if the proposed regulation were modified as suggested by the 
licensee;
    (d) How the proposed regulation, as modified, could more closely 
equalize the impact of NRC regulations or create more equal access to 
the benefits of Federal programs as opposed to providing special 
advantages to any individual or group; and
    (e) How the proposed regulation, as modified, would still 
adequately protect the public health and safety.
    The comments should be sent to the Secretary of the Commission, 
U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, ATTN: 
Rulemaking and Adjudications Staff. Hand-deliver comments to 11555 
Rockville Pike, Rockville, Maryland, between 7:30 a.m. and 4:15 p.m. on 
Federal workdays.

X. Backfit Analysis

    Although the NRC has concluded that the changes being proposed 
constitute a reduction in unnecessary regulatory burden, the 
implementation of these changes will require revisions to licensee 
procedures, thereby constituting a potential backfit under 10 CFR 
50.109(a)(1). Under Sec. 50.109(a)(2), a backfit analysis is required 
unless the proposed rule meets one of the exceptions listed in 
Sec. 50.109(a)(4). This proposed rule meets the exception at 
Sec. 50.109(a)(4)(iii) in that it is redefining the level of adequate 
protection embodied in the occupational dose limit for doses to the 
skin of the whole body and to the skin of the extremities. In addition, 
the implementation of this proposed rule is expected to result in a 
substantial increase in worker industrial safety.
    Section II, Summary and Discussion of the Proposed Changes, 
discusses the proposed changes to the definition of shallow-dose 
equivalent (SDE) and the provision for averaging SDE over the most 
highly exposed 10 square centimeters. This change would, in effect, 
raise the skin dose limit for discrete radioactive particles (DRPs) on 
or near the skin and for small-area (1.0 cm\2\) contaminations. This 
revision makes it possible for licensees to measure or calculate skin 
doses for comparison to the 50-rem (0.5 Sv) limit that when divided by 
10, result in dose values according to NCRP that more appropriately 
reflect the risk associated with small area exposures. The increased 
limit in the case of DRPs will remove the need to frequently monitor 
workers for DRP contamination during work shifts for all but the 
highest activity DRPs, especially those having a high gamma component. 
This reduced monitoring will eliminate most of the whole-body dose and 
stochastic risk associated with monitoring performed to avoid exceeding 
the current more restrictive skin dose limit. In addition, the relaxed 
skin dose limit, based on NCRP recommendations, should make it clear 
that the consequences of transient skin contamination are less 
significant than the radiological and nonradiological risks incurred by 
workers as a result of licensee efforts to avoid skin contaminations. 
The overly conservative use of multiple layers of protective clothing 
and other devices worn to prevent skin contamination cause exposure to 
nonradiological hazards such as heat stress, as well as a reduction in 
worker efficiency estimated by industry to be as much as 15-25 percent 
which, in turn, increases whole-body dose. Licensees will be able to 
choose to use less protective gear at the cost of more frequent skin 
contamination, but with the benefit of less physical stress and reduced 
whole-body dose to workers.
    In conclusion, the Commission believes that the proposed changes 
constitute a reduction in unnecessary regulatory burden that redefines 
the level of adequate protection and that should result in a 
substantial increase in worker safety. The proposed changes are 
therefore the type of change for which a backfit analysis is not 
required under Sec. 50.109(a)(4)(iii).

List of Subjects in 10 CFR Part 20

    Byproduct material, Licensed material, Nuclear materials, Nuclear 
power plants and reactors, Occupational safety and health, Packaging 
and containers, Penalty, Radiation protection, Reporting and recording 
requirements, Source material, Special nuclear material, Waste 
treatment and disposal.

    For the reasons set out in the preamble and under the authority of 
the Atomic Energy Act of 1954, as amended; the Energy Reorganization 
Act of 1974, as amended; and 5 U.S.C. 553; the NRC is proposing to 
adopt the following amendments to 10 CFR part 20.

PART 20--STANDARDS FOR PROTECTION AGAINST RADIATION

    1. The authority citation for Part 20 continues to read as follows:

    Authority: Secs. 53, 63, 65, 81, 103, 104, 161, 182, 186, 68 
Stat. 930, 933, 935, 936, 937, 948, 953, 955, as amended, Sec. 1701, 
106 Stat. 2951, 2952, 2953 (42 U.S.C. 2073, 2093, 2095, 2111, 2133, 
2134, 2201, 2232, 2236, 2297f), Secs. 201, as amended, 202, 206, 88 
Stat. 1242, as amended, 1244, 1246 (42 U.S.C. 5841, 5842, 5846).

    2. In Sec. 20.1003 the definition of Shallow-dose equivalent 
(Hs) is revised to read as follows:


Sec. 20.1003  Definitions.

* * * * *
    Shallow-dose equivalent (Hs), which applies to the 
external exposure of the skin or an extremity, is taken as the dose 
equivalent at a tissue depth of 0.007 centimeter (7 mg/cm2).
* * * * *
    3. In Sec. 20.1201 the introductory text of paragraph (a)(2), and 
paragraphs (a)(2)(ii) and (c) are revised to read as follows:


Sec. 20.1201  Occupational dose limits for adults.

    (a) * * *
    (2) The annual limits to the lens of the eye, to the skin of the 
whole body, and to the skin of the extremities, which are:
* * * * *
    (ii) A shallow-dose equivalent of 50 rem (0.5 Sv) to the skin of 
the whole body or to the skin of any extremity.
* * * * *
    (c) The assigned deep-dose equivalent must be for the part of the 
body receiving the highest exposure. The assigned shallow-dose 
equivalent must

[[Page 36509]]

be the dose averaged over the contiguous 10 square centimeters of skin 
receiving the highest exposure. The deep-dose equivalent, lens-dose 
equivalent, and shallow-dose equivalent may be assessed from surveys or 
other radiation measurements for the purpose of demonstrating 
compliance with the occupational dose limits, if the individual 
monitoring device was not in the region of highest potential exposure, 
or the results of individual monitoring are unavailable.
* * * * *

    Dated at Rockville, Maryland, this 6th day of July, 2001.

    For the Nuclear Regulatory Commission.
J. Samuel Walker,
Acting Secretary of the Commission.
[FR Doc. 01-17448 Filed 7-11-01; 8:45 am]
BILLING CODE 7590-01-P