[Federal Register Volume 68, Number 39 (Thursday, February 27, 2003)]
[Notices]
[Pages 9098-9099]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-4624]
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NUCLEAR REGULATORY COMMISSION
Handbook of Parameter Estimation for Probabilistic Risk
Assessment (PRA)
AGENCY: Nuclear Regulatory Commission (NRC).
ACTION: Announcement of issuance for public comment, availability, and
public meeting.
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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) has issued for
public comment a document entitled ``Handbook of Parameter Estimation
for Probabilistic Risk Assessment.'' This handbook provides guidance on
sources of information and methods of estimating distributions of
parameters used in probabilistic risk assessment. This includes
determination of both plant-specific and generic estimates for
initiating event frequencies, component failure rates and
unavailability, and equipment non-recovery probabilities. Interested
individuals may obtain a copy of this document from the person
identified under the caption FOR FURTHER INFORMATION CONTACT.
DATES: Please submit comments by May 23, 2003. Comments received after
this date will be considered if is practical to do so, but the NRC
Staff is able to ensure consideration only for comments received on or
before this date.
A public meeting will be held on April 2, 2003, from 8:30 a.m.
until 4:30 p.m. The purpose of this meeting is to discuss the document
and give guidance for its review and to address external stakeholder
comments received before the public meeting. The primary authors will
be available at the public meeting to answer questions and discuss
items of interest to the public.
The NRC is interested in receiving comments on specific topics
reviewers wish to discuss at the public meeting. Reviewers are
requested to contact Mr. Arthur Salomon at 301-415-6552 or e-mail
[email protected] by March 21, 2003, with comments or issues they wish to
have addressed at the public meeting.
ADDRESSES: Please submit comments to Chief, Rules and Directives
Branch, Office of Administration, U.S. Nuclear Regulatory Commission,
Washington, DC 20555-0001. Or, you may deliver comments to 11545
Rockville Pike, Rockville, Maryland, between 7:30 a.m. and 4:30 p.m.
Federal workdays.
The public meeting will be held at Two White Flint North, Room T10
A1, 11545 Rockville Pike, Rockville, Maryland.
The draft document and certain other documents related to this
action may be examined in the NRC Public Document Room, 11555 Rockville
Pike, Public File Area O1 F21, Rockville, Maryland.
FOR FURTHER INFORMATION CONTACT: Arthur D. Salomon, Division of Risk
Analysis and Applications, Office of Nuclear Regulatory Research, U.S.
Nuclear Regulatory Commission, Washington, DC 20555-0001. Telephone:
301-415-6552, e-mail: [email protected].
SUPPLEMENTARY INFORMATION: During the last several years the NRC and
the nuclear industry have recognized that PRA has evolved to the point
where it can be used as a tool in the regulatory decision-making
process. The increased use of PRA has led to the conclusion that the
PRA scope and model must be commensurate with the applications. Several
procedural guides and standards (such as the ``Standard For
Probabilistic Risk Assessment For Nuclear Power Plant Applications''
published by The American Society of Mechanical Engineers in 2002) have
been and are being developed that identify requirements for the PRA
models. This handbook was prepared to supplement these documents. It
provides a compendium of good practices that a PRA analyst can use to
develop parameter distributions required for quantifying PRA models. It
complements the ASME PRA Standard by providing guidance for estimation
of parameters related to initiating events; by describing statistical
techniques for estimating parameters used in analysis
[[Page 9099]]
of basic events such as equipment failures; and by addressing methods
for estimating equipment unavailability. Furthermore, the handbook
includes appendices describing the basics of probability and statistics
used in performing the more detailed analyses discussed in the main
portion of the document.
The handbook provides the basic information needed to generate
estimates of the parameters commonly used in PRA analysis. It begins by
describing the probability models and plant data used to evaluate each
of the parameters. Possible sources for the plant data are identified
and guidance on the collection, screening, and interpretation is
provided. The statistical techniques (both Bayesian and classical
methods) required to analyze the collected data and test the validity
of statistical models are described. Examples are provided to help the
PRA analyst utilize the different techniques. The handbook also
provides advanced techniques that address modeling of time trends.
Methods for combining data from a number of similar, but not identical
sources are also provided. This includes empirical and hierarchical
Bayesian approaches. Examples are provided to guide the analyst. The
handbook does not provide guidance on parameter estimation for all of
the events included in a PRA. Specifically, common cause failure and
human error probabilities are not addressed. In addition, guidance is
not provided regarding the use of expert elicitation. However,
suggested references regarding these technical areas are provided in
the handbook introduction.
Dated at Rockville, Maryland, this 21st day of February, 2003.
For the Nuclear Regulatory Commission.
Scott F. Newberry,
Director, Division of Risk Analysis and Applications, Office of
Nuclear Regulatory Research.
[FR Doc. 03-4624 Filed 2-26-03; 8:45 am]
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