[Federal Register Volume 68, Number 233 (Thursday, December 4, 2003)]
[Proposed Rules]
[Pages 67811-67812]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-30148]
========================================================================
Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
========================================================================
Federal Register / Vol. 68, No. 233 / Thursday, December 4, 2003 /
Proposed Rules
[[Page 67811]]
NUCLEAR REGULATORY COMMISSION
10 CFR Part 50
[Docket No. PRM-50-74]
Nuclear Energy Institute; Denial of Petition for Rulemaking
AGENCY: Nuclear Regulatory Commission.
ACTION: Petition for rulemaking: denial.
-----------------------------------------------------------------------
SUMMARY: The Nuclear Regulatory Commission (NRC) is denying a petition
for rulemaking (PRM-50-74) submitted by the Nuclear Energy Institute
(NEI or petitioner). The petitioner requested that the NRC amend its
regulations regarding emergency core cooling systems to allow licensees
the optional use of the 1994 American Nuclear Society (ANS) decay heat
standard and to allow the use of any future NRC-approved revisions of
the standard without additional rulemaking. The NRC is denying the
petition primarily because an option to use best-estimate evaluation
models is already available to its licensees, which would allow
additional operational flexibility. Also, the requested rulemaking
would reduce conservatism in an individual portion of NRC regulations
without consideration of other potential overall non-conservatism
within that portion of the regulations.
ADDRESSES: Publicly available documents related to this petition for
rulemaking may be viewed electronically on the public computers located
at the NRC's Public Document Room (PDR), O1 F21, One White Flint North,
11555 Rockville Pike, Rockville, Maryland. Documents may be copied by
the PDR reproduction contractor for a fee.
These documents are also available electronically at NRC's
Electronic Reading Room on the Internet at http://www.nrc.gov/reading-rm/adams.html. From this site, the public can gain entry into the NRC's
Agencywide Document Access and Management System (ADAMS), which
provides text and image files of NRC's public documents. For further
information contact the PDR reference staff at 1-(800) 387-4209 or
(301) 415-4737 or by e-mail to [email protected].
Selected documents, including comments, may be viewed and
downloaded electronically via the NRC rulemaking web site at http://ruleforum.llnl.gov.
FOR FURTHER INFORMATION CONTACT: Peter C. Wen, Office of Nuclear
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC
20555-0001, telephone (301) 415-2832, e-mail [email protected].
SUPPLEMENTARY INFORMATION:
Background
Section 50.46 specifies the performance criteria against which the
emergency core cooling system (ECCS) must be evaluated. The criteria
include the maximum peak cladding temperature, the maximum cladding
oxidation thickness, the maximum total hydrogen generation, and
requirements to assure a coolable core geometry and abundant long-term
cooling. This regulation also states that the calculated ECCS cooling
performance following postulated loss-of-coolant accidents (LOCAs) must
be calculated in accordance with either a realistic (also called best-
estimate) evaluation model that accounts for uncertainty or an
evaluation model that conforms with the required conservative features
of Appendix K evaluation models. The use of the 1971 ANS standard on
decay heat calculation is one of the features required in the Appendix
K ECCS evaluation models.
The Petition
On September 6, 2001, the Nuclear Energy Institute (NEI) submitted
a petition for rulemaking (PRM), designated PRM-50-74. NEI proposed a
rulemaking to amend Appendix K to 10 CFR part 50 to allow licensees the
optional use of the 1994 ANS decay heat standard and to allow the use
of any future NRC-approved revisions of the standard without additional
rulemaking.
In PRM-50-74, the petitioner stated that the 1994 ANS decay heat
standard incorporates more precise results and uses a statistical
approach to address uncertainty. The petitioner proposed a rulemaking
to amend Appendix K to 10 CFR part 50 to allow licensees the optional
use of this most current consensus decay heat standard. The petitioner
indicated that the amendment would (1) allow licensees to gain
operating margin for ECCS equipment based on the more realistic decay
heat assumptions in the 1994 ANS standard; (2) result in more effective
utilization of resources in operating and maintaining the ECCS
equipment; and (3) result in the potential for higher extended power
uprates.
Public Comments on the Petition
The notice of receipt of the petition and request for public
comment was published in the Federal Register (FR) on October 11, 2001
(66 FR 51884). The public comment period ended on December 26, 2001.
Five letters of public comment were received in response to PRM-50-74.
Four letters from industry (the Progress Energy Company, the Tennessee
Valley Authority, Strategic Teaming and Resource Sharing, and the
Nuclear Management Company) were in favor of the proposal, and one
letter from an individual (Mr. Bob Leyse) was opposed. Mr. Leyse stated
that ``the entire body of ECCS evaluation models should be reviewed by
the NRC rather than a piecemeal approach of selecting only those
aspects that may be unduly restrictive.''
Reasons for Denial
The NRC is denying PRM-50-74 primarily because Sec. 50.46 already
includes provisions for the use of best-estimate evaluation models by
NRC licensees. In addition, the request would reduce conservatism in an
individual portion of NRC regulations without consideration of other
potential overall non-conservatism within that portion of the
regulations.
The provisions of Sec. 50.46 allow licensees use of ``best-
estimate'' evaluation models to perform analysis of ECCS cooling
performance during LOCAs. This approach provides licensees with a more
accurate determination of their plants' response to a LOCA, while
allowing additional operational flexibility. The best-estimate
evaluation represents improved and modern techniques in analyzing LOCA
behavior. Thus, the NRC prefers the use of best-estimate models, rather
than the piecemeal approach to updating the Appendix K evaluation
models.
[[Page 67812]]
A concomitant factor that influenced the NRC's position is the
NRC's awareness of a number of phenomena that are known to contribute
non-conservatism to the Appendix K evaluation models. These phenomena
include boiling in the downcomer annulus during reflood, downcomer
entrainment and inventory reduction due to steam bypass, and fuel
relocation following cladding swelling during the temperature
transient. The NRC believes that if changes are made in the decay heat
standard, then changes would also have to be considered in other models
to ensure that an appropriate level of overall conservatism is retained
in the ECCS evaluation model package.
In addition, the NRC has evaluated the advantages and disadvantages
of the rulemaking requested by the petitioner with respect to the four
NRC Strategic Performance Goals as follows:
1. Maintaining Safety: The NRC believes that the requested
rulemaking would not make a significant contribution to maintaining
safety because the overall conservatism provided by the Appendix K
evaluation models may not be appropriately accounted for if the
conservatism of using the 1971 ANS decay heat standard is individually
removed.
2. Enhancing Public Confidence: The proposed rulemaking would not
enhance public confidence without an overall assessment of ECCS
evaluation model conservatism. The NRC believes that if changes are
made in the decay heat standard, then changes would also have to be
considered in other models to ensure that an appropriate level of
overall conservatism is retained in the ECCS evaluation model package.
3. Improving Efficiency and Effectiveness: The NRC staff believes
that it would not be efficient and effective to modify the Appendix K
evaluation model using a piecemeal approach when the ``best-estimate''
evaluation model is already available for licensees use.
4. Reducing Unnecessary Regulatory Burden: The NRC agrees that the
proposed rule would reduce licensees' regulatory burden. However, the
NRC does not agree that the associated burden is ``unnecessary'' in the
absence of a demonstration that overall conservatism retained in the
Appendix K evaluation models would remain adequate. For reasons cited
in this document, the NRC denies the petition.
Dated at Rockville, Maryland, this 26th day of November, 2003.
For the Nuclear Regulatory Commission.
J. Samuel Walker,
Acting Secretary of the Commission.
[FR Doc. 03-30148 Filed 12-3-03; 8:45 am]
BILLING CODE 7590-01-P