[Federal Register Volume 61, Number 6 (Tuesday, January 9, 1996)]
[Notices]
[Pages 661-669]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-283]
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NUCLEAR REGULATORY COMMISSION
Abnormal Occurrence Reports: Implementation of Section 208 Energy
Reorganization Act of 1974; Proposed Policy Statement
AGENCY: Nuclear Regulatory Commission.
ACTION: Proposed policy statement.
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SUMMARY: This policy statement presents the revised criteria the
Commission is considering for use in submitting the quarterly abnormal
occurrence (AO) reports to Congress and the public in a timely manner
as stated in Section 208 of the Energy Reorganization Act of 1974, as
amended. The AO policy statement has been revised to provide more
specific criteria for determining those incidents and events that the
Commission considers significant from the standpoint of public health
and safety for reporting to Congress, and to make the AO policy
consistent with recent changes to NRC regulations. The revised AO
criteria contain more discrete reporting thresholds making them easier
to use and ensuring more consistent application of the intended AO
reporting policy set forth by the Commission.
DATES: The public comment period on this proposed policy statement ends
April 8, 1996. Comments received after the public comment period will
be addressed if it is practicable to do so, but the Commission is able
to ensure consideration of only those comments received on or before
the last day of the comment period.
ADDRESSES: Send comments to: Secretary, U.S. Nuclear Regulatory
Commission, Washington DC 20555, Attn: Docketing and Service Branch.
Hand deliver comments to 11555 Rockville Pike, Rockville, Maryland,
between 7:45 a.m. and 4:15 p.m. Federal workdays.
Examine comments received at the NRC Public Document Room, 2120 L
Street NW (Lower Level), Washington, DC.
FOR FURTHER INFORMATION CONTACT: Harriet Karagiannis, Office for
Analysis and Evaluation of Operational Data, U.S. Nuclear Regulatory
Commission, Washington, DC 20555, telephone: (301) 415-6377.
SUPPLEMENTARY INFORMATION:
Background
Section 208 of the Energy Reorganization Act of 1974 (Public Law
93-438, 42 U.S.C. 5848), as amended, provides that:
The Commission shall submit to Congress each quarter a report
listing for that period any AOs at or associated with any facility
which is licensed or otherwise regulated pursuant to the Atomic Energy
Act of 1954, as amended, or pursuant to this Act. For the purposes of
this Section, an AO is an unscheduled incident or event which the
Commission has determined to be significant from the standpoint of
public health and safety. Nothing in the preceding sentence shall limit
the authority of a court to review the determination of the Commission.
Each such report shall contain:
(1) The date and place of each occurrence;
(2) The nature and probable consequence of each occurrence;
(3) The cause or causes of each; and
(4) Any action taken to prevent recurrence.
The Commission shall also provide as wide dissemination to the
public of the information specified in clauses (1) and (2) of this
section as reasonably possible within 15 days of its receiving
information of each AO and shall provide as wide dissemination to the
public as reasonably possible of the information specified in clauses
(3) and (4) as soon as such information becomes available to it.
In July 1975, in the exercise of the authority conferred upon the
Commission by Congress to determine which unscheduled incidents or
events are significant from the standpoint of public health and safety
and are reportable to Congress as AOs, the Commission developed interim
criteria for evaluating licensee incidents or events. On the basis of
these interim criteria and as required by Section 208, the Commission
began issuing quarterly reports to Congress on AOs. These reports
1 ``Report to Congress on Abnormal Occurrences,'' have been issued
in NUREG 75/090 and NUREG-0090-1 through 5 for the period from January
1975 through September 1976. On the basis of its experience in the
preparation and issuance of AO reports, the Commission issued a general
statement of policy that described the manner in which it will, as part
of the routine conduct of its business, carry out its responsibilities
under Section 208 of the Energy Reorganization Act of 1974, as amended,
for identifying AOs and making the requisite information concerning
each such occurrence available to Congress and the public in a timely
manner. This general statement of policy was published in the Federal
Register on February 24, 1977 (Vol. 42, No. 37, pages 10950-10952) and
provides criteria and examples of types of events that the Commission
uses in determining whether a particular event is reportable to
Congress as an AO. The Commission has since refined this statement of
policy on a number of occasions to reflect changes in regulation and
policy. On the basis of these criteria, and as required by Section 208
of the Energy Reorganization Act of 1974, as amended, the Commission
has issued quarterly reports to Congress on AOs since March 1977. These
reports,
[[Page 662]]
``Report to Congress on Abnormal Occurrences,'' have been issued in
NUREG-0090-6 through 10 and NUREG-0090, Volumes 1 through 18.
\1\ Copies of the NUREG-0090 series may be obtained from the
Superintendent of Documents, U.S. Government Printing Office, Mail
Stop SSOP, Washington, DC 20402-9328, the National Technical
Information Service, 5285 Port Royal Road, Springfield, VA 22161,
and the NRC Public Document Room, 2120 L Street, NW (Lower Level),
Washington, DC. 20037
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Based on its experience to date in the preparation and issuance of
AO reports, the Commission has decided that its responsibilities under
Section 208 can be carried out more appropriately if the existing AO
criteria are updated to reflect changes in the Commission's policy and
changes to the regulations. Accordingly, the Commission is issuing this
general statement of policy that describes the manner in which the
Commission will, as part of the routine conduct of its business, carry
out its responsibilities under Section 208 of the Energy Reorganization
Act of 1974, as amended, for identifying AOs and making the requisite
information concerning each such occurrence available to Congress and
the public in a timely manner. Included in the policy statement are
criteria that the Commission will use in determining whether a
particular event is a reportable AO within the meaning of Section 208.
It is expected that as additional experience is gained, changes in the
criteria may be required.
Paperwork Reduction Act Statement
This proposed policy statement does not contain a new or amended
information collection requirement subject to the Paperwork Reduction
Act of 1995 (44 U.S.C. 3501 et seq.). Existing requirements were
approved by the Office of Management and Budget, approval 3150-0014, 10
CFR Part 20; 3150-0017, 10 CFR Part 30; 3150-0016, 10 CFR Part 31;
3150-0001, 10 CFR Part 32; 3150-0015, 10 CFR Part 33; 3150-0007, 10 CFR
Part 34; 3150-0010, 10 CFR Part 35; 3150-0158, 10 CFR Part 36; 3150-
0130, 10 CFR Part 39; 3150-0020, 10 CFR Part 40; 3150-0011, 10 CFR Part
50; 3150-0135, 10 CFR Part 61; 3150-0009, 10 CFR Part 70; 3150-0008, 10
CFR Part 71; and 3150-0132, 10 CFR Part 72; 3150-0002, 10 CFR Part 73;
and 3150-0093, 10 CFR Part 100.
Public Protection Notification
The NRC may not conduct or sponsor, and a person is not required to
respond to, a collection of information unless it displays a currently
valid OMB control number
Abnormal Occurrence Reporting
The general statement of policy has been developed to comply with
the legislative intent of Section 208 of the Energy Reorganization Act
of 1974, as amended, to keep Congress and the public informed of
unscheduled incidents or events which the Commission considers
significant from the standpoint of public health and safety. The policy
reflects a range of health and safety concerns and is applicable to
incidents and events involving a single occupational worker as well as
those having an overall impact on the general public.
The policy statement contains criteria that include the reporting
thresholds for determining those incidents and events that are
reportable by NRC for the purposes of Section 208 of the Energy
Reorganization Act of 1974, as amended. The Commission has established
the reporting thresholds at a level which will assure that all events
that should be considered for reporting to Congress will be identified.
At the same time, the thresholds are generally above the normal level
of reporting to NRC to exclude those events which involve some variance
from regulatory limits, but are not significant from the standpoint of
public health and safety.
Licensee Reports
This general statement of policy will not change the reporting
requirements imposed on NRC licensees by Commission regulations,
license conditions, or technical specifications (TS). NRC licensees
will continue to submit required reports on a wide spectrum of events,
including events such as instrument malfunctions and deviations from
normal operating procedures that are not significant from the
standpoint of the public health and safety but which provide data
useful to the Commission in monitoring operating trends of licensed
facilities and in comparing the actual performance of these facilities
with the potential performance for which the facilities were designed
and/or licensed. Information pertaining to all events reported to NRC
will continue to be made available and placed in the public document
rooms for public perusal. In addition, NRC publishes annual reports on
events (NUREG-1272 series). Information can also be obtained by writing
to the U.S. Nuclear Regulatory Commission, Public Document Room,
Washington, DC 20555. In addition, the Commission will continue to
issue news announcements on events that seem to be newsworthy whether
or not they are reported as AOs.
The Commission invites all interested persons who wish to submit
written comments or suggestions on the AO criteria in this policy
statement. A period of 90 days from the date of publication has been
established for receiving comments pertaining to this proposed policy
statement. The NRC staff will analyze all comments and revise the
policy statement accordingly and then resubmit it to the Commission for
final approval. The policy statement is currently scheduled to be
presented to the Commission for final approval during the summer of
1996.
General Statement of Policy on Implementation of Section 208 of the
Energy Reorganization Act of 1974, as Amended
1. Applicability--Implementation of Section 208 of the Energy
Reorganization Act of 1974, as amended, Abnormal Occurrence Reports,
involves the conduct of Commission business and does not impose
requirements on licensees. Reports will cover certain unscheduled
incidents or events related to the manufacture, construction, or
operation of a facility or conduct of an activity subject to the
requirements of Parts 20, 30 through 36, 39, 40, 50, 61, 70, 71, or 72
of Chapter I, Title 10, Code of Federal Regulations (10 CFR).
Under an exchange of information program, Agreement States provide
information to NRC on incidents and events involving applicable nuclear
materials that have occurred in their States. Those events reported by
Agreement States that reach the threshold for reporting as an AO are
also published in the quarterly ``Report to Congress on Abnormal
Occurrences.''
2. Definition of terms--As used in this policy statement: (a) An
abnormal occurrence means an unscheduled incident or event at a
facility or associated with an activity that is licensed or otherwise
regulated, pursuant to the Atomic Energy Act of 1954, as amended, or
the Energy Reorganization Act of 1974, as amended, that the Commission
determines to be significant from the standpoint of public health and
safety; and (b) an unintended radiation exposure includes any
occupational exposure, exposure to the general public, or exposure as a
result of a medical misadministration (as defined in 10 CFR 35.2)
involving the wrong individual that exceeds the reporting values
established in the regulations. All other reported medical
misadministrations will be considered for reporting as an AO under the
criteria for medical licensees. In addition, unintended radiation
exposures include any exposure to a nursing infant, fetus, or embryo as
a result of an exposure (other than an occupational exposure to an
undeclared pregnant woman) to a nursing mother or pregnant woman.
3. Abnormal occurrence general statement of policy--The Commission
will apply the following policy in
[[Page 663]]
determining whether an incident or event at a facility or involving an
activity that is licensed or otherwise regulated by the Commission is
an AO within the purview of Section 208 of the Energy Reorganization
Act of 1974, as amended.
An incident or event will be considered an AO if it involves a
major reduction in the degree of protection of the public health or
safety. Such an incident or event would have a moderate or more severe
impact on the public health or safety and could include but need not be
limited to the following:
(1) Moderate exposure to, or release of, radioactive material
licensed by or otherwise regulated by the Commission;
(2) Major degradation of essential safety-related equipment; or
(3) Major deficiencies in design, construction, use of, or
management controls for licensed facilities or material.
Criteria by type of event used to determine which incidents or
events will be considered for reporting as AOs are set out in Appendix
A of this policy statement.
4. Commission dissemination of AO information.
(a) The Commission will provide as wide a dissemination of
information to the public as reasonably possible. A Federal Register
notice will be issued on each AO with copies distributed to the NRC
Public Document Room and all local public document rooms. When
additional information is anticipated, the notice will state that the
information can be obtained at the NRC Public Document Room and in all
local public document rooms.
(b) Each quarter, the Commission will submit a report to Congress
listing for that period any AOs at or associated with any facility or
activity which is licensed or otherwise regulated pursuant to the
Atomic Energy Act of 1954, as amended, or the Energy Reorganization Act
of 1974, as amended. This report will contain the date, place, nature,
and probable consequence of each AO, the cause or causes of each AO,
and any action taken to prevent recurrence.
Appendix A--Abnormal Occurrence Criteria
Criteria by types of events used to determine which incidents or
events will be considered for reporting as AOs are as follows:
I. For All Licensees
A. Human Exposure to Radiation from Licensed Material:
1. Any unintended radiation exposure to an adult (any individual 18
years of age or older) resulting in an annual total effective dose
equivalent (TEDE) of 250 millisievert (mSv) (25 rem) or more; or the
sum of the annual deep dose equivalent and committed dose equivalent to
any individual organ or tissue, other than bone marrow, the lens of the
eye, or gonads of 2500 mSv (250 rem) or more; or an annual dose
equivalent to bone marrow, the lens of the eye, or gonads of 500 mSv
(50 rem) or more; or an annual shallow-dose equivalent to the skin or
extremities of 2500 mSv (250 rem) or more.
2. Any unintended radiation exposure to any minor (an individual
less than 18 years of age) resulting in an annual TEDE of 50 mSv (5
rem) or more, or to an embryo/fetus resulting in a dose equivalent of
50 mSv (5 rem) or more.
3. Any radiation exposure that has resulted in unintended permanent
functional damage to an organ or a physiological system as determined
by a physician.
B. Discharge or Dispersal of Radioactive Material from its Intended
Place of Confinement:
1. The release of radioactive material to an unrestricted area in
concentrations which, if averaged over a period of 24 hours, exceed
5000 times the values specified in Table 2 of Appendix B to 10 CFR Part
20, unless the licensee has demonstrated compliance with 10 CFR 20.1301
using 20.1302(b)(1) or 20.1302(b)(2)(ii).
2. Radiation levels in excess of the design values for a package,
or the loss of confinement of radioactive material resulting in one or
more of the following: (a) A radiation dose rate of 10 mSv (1 rem) per
hour or more at 1 meter (3.28 feet) from the accessible external
surface of a package containing radioactive material, (b) a radiation
dose rate of 50 mSv (5 rem) per hour or more on the accessible external
surface of a package containing radioactive material and that meet the
requirements for ``exclusive use'' as defined in 10 CFR 71.47, or (c)
release of radioactive material from a package in amounts greater than
the regulatory limits in 10 CFR 71.51(a)(2).
C. Theft, Diversion, or Loss of Licensed Material, or Sabotage or
Security Breach 2:
\2\ Information pertaining to certain incidents may be either
classified or under consideration for classification because of
national security implications. Classified information will be
withheld when formally reporting these incidents in accordance with
Section 208 of the Energy Reorganization Act of 1974, as amended.
Any classified details regarding such incidents would be available
to the Congress, upon request, under appropriate security
arrangements.
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1. Any lost, stolen, or abandoned sources that exceed 0.01 times
the A1 values, as listed in 10 CFR Part 71, Appendix A, Table A-1,
for special form (sealed/nondispersible) sources, or the smaller of the
A2 or 0.01 times the A1 values, as listed in Table A-1, for
normal form (unsealed/ dispersible) sources or for sources for which
the form is not known. Excluded from reporting under this criterion are
those events involving sources that are lost, stolen, or abandoned
under the following conditions: sources abandoned in accordance with
the requirements of 10 CFR 39.77(c); sealed sources contained in
labeled, rugged source housings; recovered sources with sufficient
indication that doses in excess of the reporting thresholds specified
in AO criteria I.A.1 and I.A.2 did not occur during the time the source
was missing; and unrecoverable sources lost under such conditions that
doses in excess of the reporting thresholds specified in AO criteria
I.A.1 and I.A.2 were not known to have occurred.
2. A substantiated case of actual or attempted theft or diversion
of licensed material or sabotage of a facility.
3. Any substantiated loss of special nuclear material or any
substantiated inventory discrepancy that is judged to be significant
relative to normally expected performance, and that is judged to be
caused by theft or diversion or by substantial breakdown of the
accountability system.
4. Any substantial breakdown of physical security or material
control (i.e., access control containment or accountability systems)
that significantly weakened the protection against theft, diversion, or
sabotage.
D. Other Events (i.e., those concerning design, analysis,
construction, testing, operation, use, or disposal of licensed
facilities or regulated materials):
1. An accidental criticality [10 CFR 70.52(a)].
2. A major deficiency in design, construction, control, or
operation having significant safety implications requiring immediate
remedial action.
3. A serious deficiency in management or procedural controls in
major areas.
4. Series of events (where individual events are not of major
importance), recurring incidents, and incidents with implications for
similar facilities (generic incidents) that create a major safety
concern.
II. For Commercial Nuclear Power Plant Licensees
A. Malfunction of Facility, Structures, or Equipment:
[[Page 664]]
1. Exceeding a safety limit of license TS [10 CFR 50.36(c)].
2. Serious degradation of fuel integrity, primary coolant pressure
boundary, or primary containment boundary.
3. Loss of plant capability to perform essential safety functions
such that a release of radioactive materials, which could result in
exceeding the dose limits of 10 CFR Part 100 or 5 times the dose limits
of 10 CFR Part 50, Appendix A, General Design Criterion (GDC) 19, could
occur from a postulated transient or accident (e.g., loss of emergency
core cooling system, loss of control rod system).
B. Design or Safety Analysis Deficiency, Personnel Error, or
Procedural or Administrative Inadequacy:
1. Discovery of a major condition not specifically considered in
the safety analysis report (SAR) or TS that requires immediate remedial
action.
2. Personnel error or procedural deficiencies that result in loss
of plant capability to perform essential safety functions such that a
release of radioactive materials, which could result in exceeding the
dose limits of 10 CFR Part 100 or 5 times the dose limits of 10 CFR
Part 50, Appendix A, GDC 19, could occur from a postulated transient or
accident (e.g., loss of emergency core cooling system, loss of control
rod system).
III. For Fuel Cycle Licensees
1. A required plant shutdown as a result of violating a license
condition safety limit.
2. A major condition not specifically considered in the SAR or TS
that requires immediate remedial action.
3. An event that seriously compromises the ability of a confinement
system to perform its designated function.
IV. For Medical Licensees
A medical misadministration that:
(a) results in a dose that is (1) equal to or greater than 1 gray
(Gy) (100 rads) to a major portion of the bone marrow, to the lens of
the eye, or to the gonads, or (2) equal to or greater than 10 Gy (1000
rads) to any other organ; and
(b) represents either (1) a dose or dosage that is at least 50
percent greater than that prescribed in a written directive or (2) a
prescribed dose or dosage that (i) is the wrong
radiopharmaceutical,3 or (ii) is delivered by the wrong route of
administration, or (iii) is delivered to the wrong treatment site, or
(iv) is delivered by the wrong treatment mode, or (v) is from a leaking
source(s).
\3\ The wrong radiopharmaceutical as used in the AO criterion
for medical misadministrations refers to any radiopharmaceutical
other than the one listed in the written directive or in the
diagnostic clinical procedures manual.
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V. Guidelines for ``Other Events of Interest''
The Commission may determine that events other than AOs may be of
interest to Congress and be included in an Appendix to the AO report as
``Other Events of Interest''. Guidelines for events to be included in
the AO report for this purpose are as follows:
Items that may possibly be perceived by the public to be of health
or safety significance. Such items do not involve a major reduction in
the level of protection provided for public health or safety;
therefore, they are not reportable as abnormal occurrences. An example
is an event where upon final evaluation by an NRC Incident
Investigation Team, or an Agreement State equivalent response, a
determination is made that such event does not meet the criteria for an
abnormal occurrence.
Supplemental Information--Bases for Revised Abnormal Occurrence
Reporting Policy Statement
1. Discussion--The AO reporting policy has been developed to comply
with the legislative intent of Section 208 of the Energy Reorganization
Act of 1974, as amended, to keep Congress and the public informed of
unscheduled incidents or events which the Commission considers
significant from the standpoint of public health and safety. The policy
reflects a range of health and safety concerns related to production
and utilization facilities and the possession and use of byproduct,
source, and special nuclear materials licensed or otherwise regulated
pursuant to the Atomic Energy Act of 1954, as amended, or to the Energy
Reorganization Act of 1974, as amended. These safety concerns can
include events ranging from an overexposure of a single occupational
worker to those having an overall impact on the general public.
The revised policy statement provides a more usable policy for
determining which events will be reported to Congress as AOs. The
revised AO criteria in Appendix A contain more discrete reporting
thresholds than those previously provided in the examples of AOs for
easier and consistent application of the provisions established by the
policy statement for reporting to Congress.
The consistent application of the AO criteria by the staff,
Agreement States, and licensees for proposing events as potential AOs
to the Commission is important and requires established reporting
thresholds whenever practicable. These reporting thresholds were
selected with the intent of capturing the majority of the significant
events and eliminating nonsignificant events from those to be proposed
to the Commission.
An additional criterion has been added for those uncommon
significant events that could occur without triggering a reporting
threshold. This new criterion would require radiation exposures that
have resulted in unanticipated permanent functional damage of an organ
or physiological system, as determined by a physician, be reported to
Congress. See Criterion I.A.3 in Appendix A.
The policy statement has also been revised to include changes that
have been made to the regulations.
The revised criteria have been applied to events previously
considered as potential AOs to ensure that the new criteria will
identify significant events and eliminate nonsignificant events from
those to be proposed to the Commission. A similar review of events
involving lost, stolen, and abandoned source events has also been
performed. The results of these reviews were documented in Attachments
2, and 3 to the Commission paper, SECY-95-083, ``Revised Abnormal
Occurrence Criteria,'' dated April 5, 1995.
2. Definition of terms--Terms relating to the bases for the AO
reporting criteria are defined as follows:
(a) Nonstochastic effects are those health effects, the severity of
which varies with the dose, and for which a threshold is believed to
exist. Radiation-induced cataract formation is an example of a
nonstochastic effect (also called deterministic effect). [10 CFR
20.1003]
(b) Stochastic effects are those health effects that occur randomly
and for which the probability of the effect occurring, rather than its
severity, is assumed to be a linear function of dose without threshold.
Hereditary effects and cancer incidence are examples of stochastic
effects. [10 CFR 20.1003]
(c) Threshold dose denotes the amount of radiation below which no
effect under consideration is likely to occur. Threshold dose is
applicable to deterministic effects.
(d) Reporting threshold denotes a discrete value at or above which
an occurrence will be considered for reporting as an AO.
3. Abnormal occurrence criteria-- The AO criteria provide the
reporting threshold for determining those events that are reportable
for purposes of
[[Page 665]]
Section 208 of the Energy Reorganization Act of 1974, as amended. The
Commission has established criteria that contain reporting thresholds
intended to identify those events that are likely to be significant
from the standpoint of public health and safety. At the same time, the
AO reporting thresholds established by the criteria are generally above
the normal level of reporting events to NRC to exclude those events
which involve some variance from regulatory limits, but are not
significant enough from the standpoint of public health and safety to
be reported to Congress.
4. Basis--The following discussion provides the basis for the
changes to the AO reporting criteria as documented in Appendix A of the
policy statement.
I. For All Licensees:
A. Human Exposure to Radiation from Licensed Material:
Criterion I.A.1: Any unintended radiation exposure to an adult (any
individual 18 years of age or older) resulting in an annual total
effective dose equivalent (TEDE) of 250 millisievert (mSv) (25 rem) or
more; or the sum of the annual deep dose equivalent and committed dose
equivalent to any individual organ or tissue, other than bone marrow,
the lens of the eye, or gonads of 2500 mSv (250 rem) or more; or an
annual dose equivalent to bone marrow, the lens of the eye, or gonads
of 500 mSv (50 rem) or more; or an annual shallow-dose equivalent to
the skin or extremities of 2500 mSv (250 rem) or more. [10 CFR
20.1201(a)(1), 20.1201(a)(2), and 35.2]
Criterion I.A.2: Any unintended radiation exposure to any minor (an
individual less than 18 years of age) resulting in an annual TEDE of 50
mSv (5 rem) or more, or to an embryo/fetus resulting in a dose
equivalent of 50 mSv (5 rem) or more. [10 CFR20.1207, and 20.1301]
Criterion I.A.1 and Criterion I.A.2 have been revised to reflect
guidance provided by the Commission, and to incorporate the changes to
10 CFR Part 20, that became mandatory on January 1, 1994.
Criterion I.A.1 has been revised to establish reporting thresholds
for unintended exposures to adults including TEDEs, and individual
doses to organs, lens of the eye, skin, and extremities. The changes to
this criterion takes into consideration deterministic and stochastic
effects for the purposes of radiation protection. The bases for the
reporting thresholds are as follows.
(a) The reporting threshold for an unintended radiation exposure to
an adult (18 years of age and older) resulting in an annual TEDE of 250
mSv (25 rem) or more, is based on the following:
It is greater than the regulatory allowable TEDE limit (50
mSv [5 rem]) for annual occupational exposure established in 10 CFR
20.1201(a)(1)(i).
It is equal to the generally accepted level of exposure
that is considered by the industry to be a significant unplanned
occupational overexposure.
It is at a level of exposure for which the potential for
morbidity is considered for individuals with an increased organ and
tissue sensitivity to radiation (e.g., a genetic condition causing an
individual to be heterozygous as a result of the ataxia telangiectasia
gene 4).
\4\ T.J. McMillian; ``The Molecular Basis of
Radiosensitivity;'' In The Biological Basis of Radiosensitivity,
Second Edition; (EDS: G.G. Steel, G.E. Adams, and A. Horwich);
Elsevier Science Publishers B.V.; copyright 1989.
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(b) The reporting threshold for an unintended radiation exposure to
an organ of an adult (other than bone marrow, lens of the eye, and
gonads) resulting in the sum of the annual deep dose equivalent and
committed dose equivalent to any individual organ or tissue of 2500 mSv
(250 rem) or more is based on the following:
It is greater than the allowable regulatory limit for
occupational exposure (500 mSv [50 rem]) for the sum of the deep-dose
equivalent and the committed dose equivalent to an organ or tissue
(other than the lens of the eye) established by 10 CFR
20.1201(a)(1)(ii).
It is below the different morbidity threshold doses for
deterministic effects in radiosensitive organs such as gastrointestinal
track mortality, pulmonary lethality, and mental incapacitation.
[National Council on Radiation Protection and Measurements (NCRP)
Commentary No. 7]
(c) The reporting threshold for an unintended radiation exposure to
bone marrow, lens of the eye, or gonads of an adult resulting in 500
mSv (50 rem) or more is based on the following:
It is equal to the allowable regulatory limit for the sum
of the annual deep dose equivalent and committed dose equivalent for
occupational exposures (0.5 Sv [50 rem]) to the bone marrow or gonads;
and greater than the allowable regulatory limit (150 mSv [15 rem]) for
an annual occupational dose equivalent to the lens of the eye as
established in 10 CFR 20.1201(a)(2)(i).
It is at the threshold dose for initial signs of temporary
bone marrow depression. [NCRP Commentary No. 7]
It is at the minimum threshold dose for known
deterministic effects in the lens of the eye. [NCRP Commentary No. 7]
It is below the threshold dose for permanent sterility
from a single dose to the gonads. [NCRP Commentary No. 7]
(d) The reporting threshold for an unintended annual shallow-dose
equivalent to the skin or extremities (extremities include the hand,
elbow, arm below the elbow, foot, knee, leg below the knee) of an
adult, resulting in 2500 mSv (250 rem) or more is based on the
following:
It is greater than the allowable regulatory limit (500 mSv
[50 rem]) for annual occupational shallow-dose equivalent to the skin
or to any extremity as established in 10 CFR 20.1201(a)(2)(ii).
It is below the threshold dose for detrimental
deterministic effects in the tissue of the skin, and the bone (other
than the bone marrow) and muscle of the extremities. [NCRP Commentary
No. 7]
Criterion I.A.2 has been added in response to the Commission's
request in the SRM of May 19, 1994 on SECY-93-259, to reaffirm that a
single reporting threshold for unintended exposure is acceptable. The
potential for adverse health effects from radiation is independent of
an individual's status as a radiation worker, wrong individual, or
member of the general public. Therefore, assigning a single dose value
for unintended radiation exposures is consistent with the requirements
of Section 208 of the Energy Reorganization Act of 1974, as amended.
However, health effects are age dependent because organs and tissues in
minors, fetuses, and embryos are more radiosensitive than in a typical
adult. Because of increased radiosensitivity, a lower dose threshold
for minors (including occupational exposures to minors), fetuses, and
embryos has been included for AO reporting.
Criterion I.A.2 contains the reporting thresholds for unintended
radiation exposures to any minor. This criterion considers both
deterministic and stochastic effects for the purpose of radiation
protection.
(a) The reporting thresholds for an unintended radiation exposure
resulting in an annual TEDE of 50 mSv (5 rem) or more to a minor or a
dose equivalent of 50 mSv (5 rem) or more to an embryo/fetus are based
on the potential for permanent adverse health effects during the most
radiosensitive period from the point of conception to adulthood and
include the following:
It is greater than the allowable regulatory limit (1 mSv
[0.1 rem] or 10 percent of the limits established in 10
[[Page 666]]
CFR 20.1201) for annual exposures to individuals other than radiation
workers and occupational dose limits for minors as established in 10
CFR 20.1301 and 20.1207, respectively.
It is below the minimum threshold doses for permanent
deterministic effects in selective organs of minors because the annual
TEDE reporting threshold for minors of 50 mSv (5 rem) equates to
individual organ doses less than the known doses that will result in
deterministic effects. (Refer to item (b) below.) [NCRP Commentary No.
7]
It is below the individual threshold dose (100 mSv [10
rem]) for known permanent adverse health effects (mental retardation)
during the most radiosensitive period (8 to 15 weeks of gestation) of
embryo or fetus development. The reporting threshold (50 mSv [5 rem])
is at the threshold dose for reduced head size but no adverse health
effects are anticipated at this dose. [NCRP Commentary No. 7]
(b) Organ doses limits are not provided in this criterion because
the intent of Section 208 is addressed with the single TEDE limit based
on the following:
Individual organ doses for minors as members of the
general public would not be consistent with the requirements of 10 CFR
20.1301, ``Dose limits for individual members of the general public.''
Individual occupational organ doses for minors are defined
in 10 CFR 20.1207. The 50 mSv (5 rem) TEDE reporting threshold for
minors is 20 percent of the threshold dose established for adults in
Criterion I.A.1. If individual organ reporting thresholds for minor
occupational workers were also reduced by 20 percent (Refer to Table 1,
``Conversion from TEDE to Organ Dose''), the resulting dose values
would be close in magnitude or more conservative than organ doses that
would equate to the 50 mSv (5 rem) TEDE reporting threshold. This
assessment is based on the ``Organ Dose Weighting Factors'' as provided
in 10 CFR 20.1003 which result in the following data:
Table 1.--Conversion From TEDE to Organ Dose
----------------------------------------------------------------------------------------------------------------
Reduced** reporting
Organ Weighting Organ dose to yield threshold for Criterion I.A.1
factor 50 mSv* minors threshold
----------------------------------------------------------------------------------------------------------------
Whole Body......................... 1.0 50 mSv 50 mSv 250 mSv
Gonads............................. 0.25 200 mSv 100 mSv 500 mSv
Breast............................. 0.15 330 mSv 500 mSv 2500 mSv
Bone marrow........................ 0.12 420 mSv 100 mSv 500 mSv
Lungs.............................. 0.12 420 mSv 500 mSv 2500 mSv
Thyroid............................ 0.03 1670 mSv 500 mSv 2500 mSv
Bone surface....................... 0.03 1670 mSv 500 mSv 2500 mSv
----------------------------------------------------------------------------------------------------------------
* Organ Dose/Weighting Factor.
** 0.2 x Criterion I.A.1 reporting thresholds.
[10 CFR 20.1003, 20.1201, 20.1207, and 20.1301]
Individual organs that do not have a weighting factor are
still considered in the revised criteria by Criterion I.A.3, which
requires reporting to Congress any permanent functional damage as a
result of an exposure to an individual organ. [10 CFR 20.1003 and
20.1301]
Criterion I.A.3: Any radiation exposure that has resulted in
unintended permanent functional damage to an organ or a physiological
system as determined by a physician. [General]
Criterion I.A.3 has been added to identify for reporting those
incidents or events that have resulted in an organ or physiological
system morbidity or mortality at dose levels below the established AO
reporting thresholds.
B. Discharge or Dispersal of Radioactive Material from its Intended
Place of Confinement:
Criterion I.B.1: The release of radioactive material to an
unrestricted area in concentrations that, if averaged over a period of
24 hours, exceed 5000 times the values specified in Table 2 of Appendix
B to 10 CFR Part 20, unless the licensee has demonstrated compliance
with 10 CFR 20.1301 using 20.1302(b)(1) or 20.1302(b)(2)(ii). [10 CFR
20.1301, 20.1302(b)(1), or 20.1302(b)(2)(ii)]
Criterion I.B.1 has been revised to reflect changes to 10 CFR Part
20 that became mandatory on January 1, 1994, and to maintain the same
thresholds for reporting as required by the existing AO criterion. The
existing reporting threshold of ``500 times the regulatory limit of
Appendix B, Table II, 10 CFR Part 20'' was increased to ``5000 times
the values specified in Table 2 of Appendix B to 10 CFR Part 20''
because the implied dose limit of 5 mSv (500 mrem) used to calculate
the concentration values in Table 2 of Appendix B was decreased to 0.5
mSv (50 mrem) in the revision to 10 CFR Part 20.
Criterion I.B.2: Radiation levels in excess of the design values
for a package, or the loss of confinement of radioactive material
resulting in one or more of the following: (a) a radiation dose rate of
10 mSv (1 rem) per hour or more at 1 meter (3.28 feet) from the
accessible external surface of a package containing radioactive
material, (b) a radiation dose rate of 50 mSv (5 rem) per hour or more
on the accessible external surface of a package containing radioactive
material and that meet the requirements for ``exclusive use'' as
defined in 10 CFR 71.47, or (c) release of radioactive material from a
package in amounts greater than the regulatory limits in 10 CFR
71.51(a)(2). [10 CFR 71.47(a) and 71.51(i)(1)]
Criterion I.B.2 has been revised to take into consideration
additional regulatory requirements in 10 CFR Part 71. This criterion
has been changed to include limits for packages that meet the
requirements for ``exclusive use'' as defined in 10 CFR 71.47, a
radiation dose rate of 50 mSv (5 rem) per hour or more on the
accessible external surface of a package containing radioactive
material, or the loss of confinement of radioactive material from a
package in amounts greater than the regulatory limits.
The contamination requirement was removed from this criterion
because certain shipping casks often experience contamination beyond
licensee control after decontamination requirements had
[[Page 667]]
been met as a result of contaminants ``leaching'' from the pores of the
outer surface of the shipping cask. This leaching effect typically
occurs as a result of condensation on the exterior of the shipping cask
that occurs during shipping. Contamination from this phenomena is not a
public health and safety concern and will not be reported to Congress.
C. Theft, Diversion, or Loss of Licensed Material, or Sabotage or
Security Breach:
Criterion I.C.1: Any lost, stolen, or abandoned sources that exceed
0.01 times the A 1 values, as listed in 10 CFR Part 71, Appendix
A, Table A-1, for special form (sealed/non-dispersible) sources, or the
smaller of the A2 or 0.01 times the A1 values, as listed in
Table A-1, for normal form (unsealed/ dispersible) sources or for
sources for which the form is not known. Excluded from reporting under
this criterion are those events involving sources that are lost,
stolen, or abandoned under the following conditions: sources abandoned
in accordance the requirements of 10 CFR 39.77(c); sealed sources
contained in labeled, rugged source housings; recovered sources with
sufficient indication that doses in excess of the reporting thresholds
specified in AO criteria I.A.1 and I.A.2 did not occur during the time
the source was missing; and unrecoverable sources lost under such
conditions that doses in excess of the reporting thresholds specified
in AO criteria I.A.1 and I.A.2 were not known to have occurred. [10 CFR
20.2201(a)(i), 30.50(a), 40.60(a), and 70.50(a)]
Criterion I.C.1 has been revised to include the reporting of lost
or stolen sources that exceed 0.01 times the A1 values, as listed
in 10 CFR Part 71, Appendix A, Table A-1, for ``special form'' (sealed/
nondispersible) sources, or the smaller of the A2 or 0.01 times
the A1 values, as listed in Table A-1, for ``normal form''
(unsealed/dispersible) sources. Excluded from reporting under this
criterion are those events involving sources that are lost, stolen, or
abandoned under the following conditions: sources abandoned per the
requirement of 10 CFR 39.77(c); sealed sources contained in labeled,
rugged source housings; recovered sources with sufficient indication
that doses in excess of the reporting thresholds specified in AO
criteria I.A.1 and I.A.2 did not occur during the time the source was
missing; and unrecoverable sources lost under such conditions that
doses in excess of the reporting thresholds specified in AO criteria
I.A.1 and I.A.2 were not known to have occurred. These reporting
thresholds are based on not exceeding an effective or committed
effective dose equivalent of 50 mSv (5 rem); a committed dose
equivalent to any individual organs including the skin of 0.5 Sv (50
rem); or in special cases, a 0.15 Sv (15 rem) dose to the lens of the
eye of any member of the general public, assuming that an exposure
occurs as a result of a source being stolen or lost.
(a) The A1 values in 10 CFR Part 71, Appendix A, Table A-1,
represent the source strength for sealed (nondispersible) sources that
will result in exceeding an effective dose equivalent of 50 mSv (5
rem), from an exterior exposure at 1 meter (3.28 feet [ft]) for 30
minutes. The proximity and duration factors of 1 meter (3.28 ft) for 30
minutes are based on the estimated exposure conditions during a
transportation accident involving licensed materials, typically a
controlled situation.
For the loss or theft of a sealed source, it has been
conservatively calculated in a study 5 performed by Oak Ridge
Institute for Science and Education (ORISE) that the accident-weighted
average exposure proximity and duration factors are 1 meter for 46
hours for the improper transfer or disposal of licensed material. To
account for the longer duration at 1 meter, from 30 minutes to 46 hours
(approximately 1:100), conservatively assuming that the entire exposure
is received by one individual, the A1 values in 10 CFR Part 71,
Appendix A, Table A-1, will need to be decreased by a factor of 100.
The multiples (0.01 x A1 values) of the A1 values in 10 CFR
Part 71, Appendix A, Table A-1, will determine the source strength of a
source that will result in exceeding an effective dose equivalent of 50
mSv (5 rem) from external exposures.
\5\ Daniel J. Strom, Ph.D., C.H.P., Staff Scientist, Operational
Health Physics Group, Health Protection Department, Pacific
Northwest Laboratory, ``Improper Transfer/Disposal Scenarios for
Generally Licensed Devices Study,'' Task 7, June 3, 1994.
---------------------------------------------------------------------------
(b) The A2 values in 10 CFR Part 71, Appendix A, Table A-1,
represent the source strength for an unsealed source (dispersible) that
will result in a deep dose equivalent or committed dose equivalent to
any individual organs of 0.5 Sv (50 rem), a shallow dose equivalent to
the skin of 0.5 Sv (50 rem), or in special cases, a 0.15 Sv (15 rem)
dose equivalent to the lens of the eye. These dose values are based on
the assumptions that the estimated release fraction ranges from 10
-3 to 10 -2 and the uptake fraction ranges from 10 -4 to
10 -3 from inhalation and/or ingestion (average fraction-taken-in
= 10 -6).
In the ORISE study, the average fraction-taken-in from inhalation
and ingestion of an improper transfer or disposal of an unsealed
(dispersible) source was calculated to be 2 x 10 -6. This
calculated value was based on the review of an actual accident with
extensive uptake information (for 194 cleanup workers and 77 members of
the general public). Both average fraction-taken-in values for
transportation accidents, and events involving lost or stolen sources
are comparable. Therefore, the A2 values can be used directly to
determine the source strengths for lost and stolen unsealed sources
that will result in a deep dose equivalent, committed dose equivalent,
or shallow dose equivalent of 0.5 Sv (50 rem).
The smaller of the two values, the A2 or 0.01 times the
A1 values, is used for a dispersible source because the material
may not be dispersed and can perform as a sealed source resulting in
external exposure. Therefore, if the source strength is greater than
the 0.01 times the A1 value or greater than the A2 value, the
potential exists for exceeding an effective or committed effective dose
equivalent of 50 mSv (5 rem); a committed dose equivalent to any
individual organs, including the skin, of 0.5 Sv (50 rem); or in
special cases, a 0.15 Sv (15 rem) dose equivalent to the lens of the
eye. If the form of the source material is unknown, the smaller of the
two values is also used to ensure all potentially reportable incidents
and events are submitted to the Commission for consideration as an AO.
(c) Sources abandoned in accordance with the requirement of 10 CFR
39.77(c) are excluded from reporting because these sources do not
represent an uncontrolled condition or potential effects adverse to
public health and safety.
(d) Sealed (nondispersible) sources contained in labeled, rugged
source housings are excluded from reporting to Congress because public
health and safety have been shown to be reasonably protected during the
loss or theft of sources that are maintained in source housings. This
exclusion is based on the following reasons:
A sealed source as defined in NRC Regulatory Guide 10.10
is radioactive material contained in a protective envelope (capsule),
contained in a foil, or plated on an inactive surface that serves as a
dispersion barrier.
A source housing as defined in American National Standard
Institute (ANSI) N538 is an enclosure containing or incorporating the
source, source holder, and a means of attenuation (shielding) of the
radiation.
A source housing is generally required to be designed and
constructed
[[Page 668]]
with ``rugged'' characteristics so that its integrity will be
maintained under normal conditions of use and under likely accident
conditions and with safety mechanisms installed to prevent accidental
access to the source. In addition, many general licensed housings are
designed to restrict access to the source for other than its specific
intended use.
ANSI N538 3.4.1 recommends sufficient shielding for
shielded gauges to limit dose rates to 0.05 mSv (5 mrem) per hour at 30
centimeters (cm) (11.8 inches), and 10 CFR 34.21(a) requires sufficient
shielding for radiography sources to limit exposure rates to 12.9 x
10 -5 coulombs per kilogram (50 milliroentgen) per hour at 15.2 cm
(6 inches). Assuming a conversion factor of 1 roentgen to 1 rem, these
shielding recommendations will ensure that an effective dose equivalent
of 50 mSv (5 rem) is not exceeded, or in special cases, a 0.15 Sv (15
rem) dose equivalent to the lens of the eye from a 46-hour exposure to
these shielded sources at 1 meter.
The A1 values in 10 CFR Part 71, Appendix A, Table A-
1, assumes that the shielding and containment are completely lost. This
loss, however, on the basis of a historical review of 1991-1993 events
involving lost and stolen sources that were later found, is unlikely
for sources contained in source housings.
The source housings typically used in these applications
make it difficult to access the source.
Source housings with the proper ``radioactive labels''
displayed have often been reported by members of the general public to
the proper authorities. The radiation symbol is easily identified,
relatively well known, and readily recognized as an indicator of a
safety hazard.
A review of the events reported for 1991-1993 that
involved the loss or theft of portable gauges and radiography devices
contained in rugged source housings verified that no known exposure
from the loss of these types of devices had occurred.
(e) Many lost or stolen sources are recovered with sufficient
indication that doses in excess of the reporting thresholds specified
in AO criteria I.A.1 and I.A.2 did not occur during the time the source
was missing. A recovered source, without any indication of exceeding
the dose thresholds specified in AO criteria I.A.1 or I.A.2 is not
significant from the standpoint of public health and safety.
(f) Any unrecoverable source lost under such conditions (e.g.,
plane crash, fire, etc.) that doses in excess of the reporting
thresholds specified in AO criteria I.A.1 and I.A.2 were not known to
have occurred is not significant from the standpoint of public health
and safety.
Criterion I.C.2: No change to this criterion.
Criterion I.C.3: No change to this criterion.
Criterion I.C.4: No change to this criterion.
D. Other Events (i.e., those concerning design, analysis,
construction, testing, operation, use or disposal of licensed
facilities or regulated materials):
Criterion I.D.1: No change to this criterion.
Criterion I.D.2: No change to this criterion.
Criterion I.D.3: No change to this criterion.
Criterion I.D.4: No change to this criterion.
II. For Commercial Nuclear Power Plant Licensees
A. Malfunction of Facilities, Structures, or Equipment:
Criterion II.A.1: No change to this criterion.
Criterion II.A.2: Serious degradation of fuel integrity, primary
coolant pressure boundary, or primary containment boundary.
Criterion II.A.2 was edited to better paraphrase the wording in 10
CFR 50.72(b)(B)(ii).
Criterion II.A.3: Loss of plant capability to perform essential
safety functions such that a release of radioactive materials, which
could result in exceeding the dose limits of 10 CFR Part 100 or 5 times
the dose limits of 10 CFR Part 50, Appendix A, General Design Criterion
(GDC) 19, could occur from a postulated transient or accident (e.g.,
loss of emergency core cooling system, loss of control rod system). [10
CFR Part 50.34(a)(1), 50.72(b)(2)(iii), and 50.73(a)(2)(v)]
Criterion II.A.3 has been revised to include a reference to 5 times
the dose limits in 10 CFR Part 50, Appendix A, GDC 19. This reference
adds control room habitability reporting requirements consistent with
the AO overexposure reporting requirements established in Criterion
I.A.1, ``For All Licensees.''
B. Design or Safety Analysis Deficiency, Personnel Error, or
Procedural or Administrative Inadequacy:
Criterion II.B.1: No change to this criterion.
Criterion II.B.2: Personnel error or procedural deficiencies that
result in loss of plant capability to perform essential safety
functions such that a release of radioactive materials, which could
result in exceeding the dose limits of 10 CFR Part 100 or 5 times the
dose limits of 10 CFR Part 50, Appendix A, GDC 19, could occur from a
postulated transient or accident (e.g., loss of emergency core cooling
system, loss of control rod system). [10 CFR 50.34(a)(1) and
50.73(b)(2)(ii)(J)]
Criterion II.B.2 has been revised to include a reference to 5 times
the dose limits in 10 CFR Part 50, Appendix A, GDC 19. This reference
adds control room habitability reporting requirements consistent with
the AO overexposure reporting requirements established in Criterion
I.A.1, ``For All Licensees.''
III. For Fuel Cycle Licensees
Criterion III.1: A required plant shutdown as a result of violating
a license condition safety limit. [10 CFR 50.36(c)]
Criterion III.1 has been revised to more appropriately reference
all license conditions rather than just TS.
Criterion III.2: No change to this criterion.
Criterion III.3: No change to this criterion.
IV. For Medical Licensees
The criterion for AO reporting of medical misadministrations to
patients intended to receive a diagnostic or therapeutic exposure has
been revised as follows:
A medical misadministration that:
(a) results in a dose that is (1) equal to or greater than 1 gray
(Gy) (100 rads) to a major portion of the bone marrow, to the lens of
the eye, or to the gonads, or (2) equal to or greater than 10 Gy (1000
rads) to any other organ; and
(b) represents either (1) a dose or dosage that is at least 50
percent greater than that prescribed in a written directive or (2) a
prescribed dose or dosage that (i) is the wrong radiopharmaceutical, or
(ii) is delivered by the wrong route of administration, or (iii) is
delivered to the wrong treatment site, or (iv) is delivered by the
wrong treatment mode, or (v) is from a leaking source(s). [10 CFR Part
35, International Council on Radiation Protection (ICRP) 41, and NCRP
Commentary No. 7]
Medical uses of radiation result in diagnostic or therapeutic
exposures for the purpose of diagnosing or treating a disease,
alleviating pain, and/or minimizing the spread of disease. With this in
mind, the AO reporting criterion has been revised to provide a simpler
method for evaluating medical misadministrations, and to assure that
only those events determined to be significant from the standpoint of
public health and safety are reported. The
[[Page 669]]
threshold doses that were selected are sufficiently below the
thresholds for deterministic effects recognizing the normal treatment
practice of collimation and fractionation of doses, where one would
expect to see permanent organ and tissue damage for most radiosensitive
organs in a typical adult, and provide a margin of error to identify
the potential for harm.
Doses used for diagnostic purposes are relatively small and result
in limited risk of adverse health effects. However, the risk, albeit
small, that exists for selected diagnostic procedures has been
considered during the selection of the reporting thresholds for the
revised criterion.
Doses used for therapeutic purposes in treating cancer customarily
approach or exceed the tolerance of normal tissue. Therefore, because
therapeutic radiation doses are intended to kill cells, harmful side-
effects might be expected from the radiation dose prescribed. The
difference between the intended and most misadministered doses has
little added effect on long-term risk such as cancer. The demonstrated
benefits from the use of byproduct materials in medical applications
and the long-term and/or short-term consequences as a result of a
medical misadministration, were considered in developing the revised
criterion.
The criterion for medical licensees has been revised to consider
dose limits that are applicable to teletherapy, brachytherapy, gamma
stereotactic radiosurgery, radiopharmaceutical therapy, and sodium
iodide and diagnostic misadministrations. A medical misadministration
(as defined by 10 CFR 35.2) involving the wrong individual will be
considered for reporting as an AO under the revised criteria for
unintended exposure (criteria I.A.1 and I.A.2) because it involves an
individual who did not give prior consent to being exposed, and who is
not expected to receive any benefit from an exposure to radiation.
However, an administration to the wrong individual must meet the
requirements for a medical misadministration as specified in 10 CFR
35.2 before being considered for reporting as an AO.
(a) The threshold dose of 1 Gy (100 rads) for bone marrow, lens of
the eye, or gonads is based on the following:
It is below the threshold (1.5 Gy [150 rads]) for bone
marrow mortality with minimum medical care. [NCRP Commentary No. 7]
It is equal to the threshold where cataracts begin to
form. [NCRP Commentary No. 7]
It is below the initial threshold (3 Gy [300 rads]) where
permanent sterility may be seen from a single exposure. [NCRP
Commentary No. 7]
(b) The reporting threshold of 10 Gy (1000 rads) selected for all
organs other than bone marrow, lens of the eye, and gonads, is based on
the following:
It is below the threshold doses at which one would expect
to see permanent organ or tissue damage from normal treatment practices
for most radiosensitive organs in adults. [NCRP Commentary No. 7]
It provides a margin of safety for errors in established
threshold doses for most radiosensitive organs in adults.
It is at the estimated threshold dose for some clinically
detrimental deterministic effects from conventionally fractionated
therapeutic irradiation that can result in permanent adverse health
effects in 1 to 5 percent of the patients treated. The permanent
effects seen at this threshold dose include the absence of development
and arrested growth in the breast and cartilage of children,
respectively. [NCRP Commentary No. 7]
These values are based on the minimal normal tissue tolerance dose,
which is defined as the dose to which a given population of patients is
exposed, under a standard set of treatment conditions, resulting in no
more than a 5-percent severe complication rate within 5 years after
treatment. These threshold doses apply to conditions of irradiation
relevant to radiotherapy, that is, doses of conventionally fractionated
``x'' or gamma radiation that must be delivered to tissue to cause a
serious deterministic effect. In addition, these thresholds allow for a
higher dose to be delivered differentially to the tumor. [ICRP 41, and
NCRP Commentary No. 7]
V. Guidelines for ``Other Events of Interest''
The Commission may determine that events other than AOs may be of
interest to Congress and the public and therefore should be included in
an Appendix to the AO report as ``Other Events of Interest''. The
guidelines for ``Other Events of Interest'' have been revised to
include events that may be perceived by the public to be of health and
safety significance and involve substantial regulatory response, but do
not otherwise meet the AO criteria. An example is an event where upon
final evaluation by an NRC Incident Investigation Team, or an Agreement
State equivalent response, a determination is made that such event does
not meet the criteria for an abnormal occurrence.
Dated at Rockville, Maryland, this 3rd day of January 1996.
For the Nuclear Regulatory Commission.
John C. Hoyle,
Secretary of the Commission.
[FR Doc. 96-283 Filed 1-8-96; 8:45 am]
BILLING CODE 7590-01-P
