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RE: Discrete Particle Threshold
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
August 2, 1990
Information Notice No. 90-48: ENFORCEMENT POLICY FOR HOT PARTICLE
EXPOSURES
Addressees:
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose:
This information notice is intended to alert addressees to a policy
statement that the U.S. Nuclear Regulatory Commission (NRC) is issuing
concerning the use of enforcement discretion in cases involving occupational
doses to the skin from exposure to radioactive particles ("hot particles")
that exceed the limits in Section 20.101 of Title 10 of the Code of Federal
Regulations (10 CFR). It is expected that recipients will review the
information for applicability to their facilities. However, the enforcement
policy is a policy statement concerning NRC actions, not a regulation
imposing requirements on licensees, and suggestions contained in this
information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Background:
The limits on occupational dose specified in the table in paragraph (a) of
10 CFR 20.101 for the hands and forearms, feet and ankles, and the skin of
the whole body apply to all exposures, including hot particle exposures.
However, because of the nature of the principal radiation involved (beta
particles), the extremely localized effects, and the lower risk of
biological injury compared to nonlocalized effects, the NRC believes a
different limit for hot particle exposures should be established through
rulemaking action. To begin the necessary rulemaking process, the
Commission has directed the NRC staff to prepare an advance notice of
proposed rulemaking by September 1990. In addition, NRC enforcement
discretion will be applied until a new limit for hot particle exposures is
established by rule.
Earlier this year, the staff proposed an NRC enforcement policy statement
(Reference 1) concerning the use of enforcement discretion in cases
involving occupational doses to the skin from hot particle exposures that
exceed the
9007270021
.
IN 90-48
August 2, 1990
Page 2 of 3
limits in 10 CFR 20.101. On July 9, 1990, the Commission approved this
statement, which is enclosed as Attachment 2. The enforcement policy
statement is based on the recommendations in Report No. 106 of the National
Council on Radiation Protection and Measurements (NCRP) (Reference 2).
In general, the policy statement increases the dose threshold for issuing a
notice of violation and decreases the severity levels for violations of the
skin dose limits and for failures to report those violations in cases of hot
particle exposures.
Discussion:
On July 30, 1990, the NRC published the new policy statement in the Federal
Register and the policy became effective on the date of publication.
As indicated in the Scope section of the attached policy, the policy applies
to occupational doses to the skin that exceed the limits of 10 CFR 20.101
for the "hands and forearms, feet and ankles" or the "skin of the whole
body" and that result from radiation emitted by a hot particle on the body
or clothing of the exposed individual. The policy does not change the
limits of 10 CFR 20.101, the methods for determining compliance with those
limits, or reporting and notification requirements of 10 CFR Parts 19 and
20. The NRC will use the notifications and reports to address issues during
the rulemaking process and to monitor licensees' continuing programs to
protect workers from hot particle exposures.
Consistent with the recommendations in NCRP Report No. 106, the definition
of a "hot particle" in the attached policy includes an upper limit on
particle size of 1 mm in any dimension. However, the NRC staff expects that
an actual measurement of the size of a particle will be necessary only if
the particle appears to have some dimension that is estimated to approach 1
mm. All particles that are not visible without magnification can be assumed
to be smaller than the limit.
NCRP Report No. 106 includes a recommendation for medical evaluation in
cases of hot particle exposures that exceed the NCRP-recommended limit of 75
microcurie hours. Because this recommendation is not considered an
enforcement issue, it is not addressed in the attached enforcement policy.
However, the NRC staff agrees with this NCRP recommendation.
The NRC staff does not intend that the implementation of this policy will
significantly alter licensee programs established to contain hot particles
within each nuclear power plant and prevent the particles from being
inadvertently transported offsite.
.
IN 90-48
August 2, 1990
Page 3 of 3
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate NRC regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: John D. Buchanan, NRR
(301) 492-3184
James E. Wigginton, NRR
(301) 492-1059
Attachments:
1. References
2. Enforcement Policy for Cases of Occupational
Doses to the Skin from Radiation Emitted
from Hot Particles
3. List of Recently Issued NRC Information Notices
.
Attachment 1
IN 90-48
August 2, 1990
Page 1 of 1
REFERENCES
1. "Modified Enforcement Policy for Hot Particle Exposures - Revision to
Incorporate Recommendations Made in NCRP Report No. 106," memorandum
for the Commissioners from James M. Taylor, Executive Director for
Operations, SECY-90-169, May 11, 1990. This NRC document is available
in the NRC Public Document Room, 2120 L Street, N.W., Washington, D.C.
2. Limit for Exposure to "Hot Particles," National Council on Radiation
Protection and Measurements (NCRP) Report No. 106, December 31, 1989.
This report is available from NCRP, 7910 Woodmont Avenue, Bethesda, MD
20814.
.
Attachment 2
IN 90-48
August 2, 1990
Page 1 of 4
Enforcement Policy for
Cases of Occupational Doses to
the Skin from Radiation
Emitted from Hot Particles
1. Purpose
The purpose of this policy statement is to explain the enforcement
policy that the Commission intends to follow (notwithstanding the
current enforcement policy in 10 CFR Part 2, Appendix C), regarding the
use of enforcement discretion in cases that involve an occupational
dose to the skin resulting from exposure to radiation emitted from a
hot particle on or near the skin. The provisions of this policy will
be followed by the NRC staff until a new limit applicable to such cases
is established by revision of 10 CFR Part 20.
2. Scope
This policy applies only to occupational doses to the skin that exceed
the limits of 10 CFR 20.101 for the "hands and forearms, feet and
ankles" or the "skin of the whole body" and that are the result of
radiation emitted from a hot particle on the body or clothing of the
exposed individual. This policy does not change criteria for
whole-body doses.
3. Definitions
As used in this policy --
"Beta emission" means either (1) the number of beta particles emitted
from the radionuclide(s) in the hot particle during the time period of
the occupational exposure of the skin or (2) the number of beta
particles emitted from the surface of the particle during that time
period.
"Hot particle" means a discrete radioactive fragment that is insoluble
in water and is less than 1 mm in any dimension.
"Hot particle exposure" means an occupational dose to the skin
resulting from exposure to radiation emitted from the radionuclides in
a hot particle on the body or on the clothing of the exposed
individual.
"Occupational dose" includes exposure of an individual to radiation (1)
in a restricted area or (2) in the course of employment in which the
individual's duties involve exposure to radiation, provided, that
"occupational dose" shall not be deemed to include any exposure of an
individual to radiation for the purpose of medical diagnosis or medical
therapy of such individual. (Note: This is the definition of this
term given in 10 CFR Part 20.)
.
Attachment 2
IN 90-48
August 2, 1990
Page 2 of 4
4. Occupational Exposure Criteria
The limits on occupational dose specified in the table in paragraph (a)
of 10 CFR 20.101 for the hands and forearms, feet and ankles, and the
skin of the whole body apply to all exposures, including hot particle
exposures. However, because of the nature of the principal radiation
involved (beta), the extremely localized effects, and the lower
biological risk, the NRC believes a different limit for hot particle
exposures should be established through rulemaking action and that
enforcement discretion should be applied until a new limit for hot
particle exposures is established by rule. Consequently, the staff
will use a new beta emission criterion and a new skin dose criterion
for determining appropriate discretionary enforcement actions and
appropriate severity levels for hot particle exposures; however, the
staff will continue to evaluate hot particle exposures in terms of
absorbed dose for comparison with the limits of 10 CFR 20.101.
For a hot particle exposure of an individual above the limits of 10 CFR
20.101 that results from a hot particle in contact with the skin, the
NRC will issue a notice of violation if the beta emission from the
particle is greater than the beta emission criterion. For purposes of
this policy, the beta emission criterion is established as a beta
emission value of 1010 beta particles (75 microcurie hours). A notice
of violation will not be issued when an individual receives a hot
particle exposure that is equal to or less than the beta emission
criterion.
For each hot particle exposure, the hot particle will be assumed to
have been in contact with the skin throughout the possible irradiation
period, even if the particle was found on the hair or clothing of the
exposed individual, unless it can be determined that the particle was
never in contact with the skin (for example, if the particle was
between two layers of clothing).
If it can be determined that the particle was never in contact with the
skin, the skin dose criterion, rather than the beta emission criterion,
applies. That is, in this case, the NRC will issue a notice of
violation if the dose to the skin exceeds the skin dose criterion. For
purposes of this policy, the skin dose criterion is established as an
occupational dose to the skin of 50 rad at a depth of 7 mg/cm 2
averaged over an area of 1 cm 2 in the region of the highest dose. A
notice of violation will not be issued when an individual receives a
hot particle exposure that is equal to or less than the skin dose
criterion.
The beta emission criterion or the skin dose criterion will be used for
each hot particle exposure. There are no quarterly or annual
limitations.
In any case, a notice of violation may be issued for violations of
other regulatory requirements associated with an event involving hot
particle exposures (e.g., violation of 10 CFR 20.201, "Surveys")
regardless of the magnitude of the hot particle exposure.
.
Attachment 2
IN 90-48
August 2, 1990
Page 3 of 4
In determining whether a hot particle exposure has exceeded the limits
of 10 CFR 20.101, the beta emission criterion, or the skin dose
criterion, hot particle exposures will not be added to skin doses from
sources other than hot particles, nor will hot particle exposures from
different particles be summed unless the different particles result in
doses to the same area (location) of skin.
5. Records, Notifications, and Reports
Nothing in this policy should be construed as changing, or in effect
changing, other requirements of 10 CFR Parts 19 and 20. In particular,
the requirements of 10 CFR 20.401 (records), 10 CFR 20.403
(notifications of incidents), 10 CFR 20.405 (reports of overexposures),
10 CFR 20.408 (reports of personnel monitoring on termination), and
10 CFR 20.409 and 10 CFR 19.13 (notifications and reports to
individuals) remain in effect and concern the current dose limits in
10 CFR 20.101. For example, a hot particle exposure resulting in a
skin dose of 75 rads to the feet, ankles, hands, or forearms must be
reported to the NRC within 24 hours. However, no notice of violation
will be issued for a failure to make an immediate notification required
by 10 CFR 20.403(a) for a skin dose that is a result of a hot particle
exposure. A Notice of Violation will be issued for a failure to make a
24-hour notification required by 10 CFR 20.403(b) or to report as
required by 10 CFR 20.405 for a dose that is a result of hot particle
exposure.
6. Enforcement Examples
In addition to the enforcement discretion concerning issuing notices of
violations, enforcement discretion also will be used concerning the
severity levels of violations. For a dose to the skin from hot
particle exposures, the following examples will be used for determining
severity levels:
a. Severity Level III - Violations involving, for example --
(1) Hot particle exposures for which the dose to the skin exceeds
the limits of 10 CFR 20.101 and exceeds three times the
relevant criterion (either the beta emission criterion or the
skin dose criterion).
(2) Failure to make a notification required by 10 CFR 20.403(b)
or a report (required by 10 CFR 20.405) for a hot particle
exposure that results in a skin dose that exceeds the limits
of 10 CFR 20.101 and exceeds three times the relevant
criterion (either the beta emission criterion or the skin
dose criterion).
b. Severity Level IV - Violations involving, for example --
.
Attachment 2
IN 90-48
August 2, 1990
Page 4 of 4
(1) Hot particle exposures for which the dose to the skin exceeds
the limits of 10 CFR 20.101 and exceeds the relevant
criterion but does not exceed three times the relevant
criterion (either the beta emission criterion or the skin
dose criterion).
(2) Failure to make a notification required by 10 CFR 20.403(b)
or a report (required by 10 CFR 20.405) for a hot particle
exposure that results in a skin dose that exceeds the limits
of 10 CFR 20.101 and exceeds the relevant criterion but does
not exceed three times the relevant criterion (either the
beta emission criterion or the skin dose criterion).
c. Severity Level V - Violations involving, for example --
(1) Failure to make a notification required by 10 CFR 20.403(b)
or a report (required by 10 CFR 20.405) for a hot particle
exposure that results in a skin dose that exceeds the limits
of 10 CFR 20.101 but that does not exceed the relevant
criterion (either the beta emission criterion or the skin
dose criterion).
Note: No numerical criteria (beta emission values or skin doses) have
been established as examples for Severity Levels I and II.
.ENDEND
Floyd Flanigan B.S.Nuc.H.P.
-----Original Message-----
From: Robinson, Stephen D. [mailto:sdrobin@nppd.com]
Sent: Tuesday, July 16, 2002 10:25 AM
To: Radsafe (E-mail)
Subject: Discrete Particle Threshold
Radsafer's:
What is the working definition of a discrete radioactive particle, or "hot
particle"? Is there an activity threshold that must be met before
radiological controls are placed into effect?
Thanks.
Stephen D. Robinson
Staff Health Physicist
NPPD, Cooper Station
(402)825-5685
sdrobin@nppd.com
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