[Federal Register Volume 65, Number 173 (Wednesday, September 6, 2000)]
[Notices]
[Pages 54081-54082]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-22781]
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NUCLEAR REGULATORY COMMISSION
[DOCKET NO. 50-352]
Peco Energy Company; Limerick Generating Station, Unit 1;
Environmental Assessment and Finding of No Significant Impact
The U.S. Nuclear Regulatory Commission (NRC) is considering
issuance of an exemption from certain requirements of 10 CFR 50.60(a)
for Facility Operating License No. NPF-39, issued to PECO Energy
Company (PECO, or the licensee) for operation of the Limerick
Generating Station, Unit 1 (Limerick Unit 1), located in Montgomery and
Chester Counties in Pennsylvania.
Environmental Assessment
Identification of the Proposed Action
Appendix G to Title 10 of the Code of Federal Regulations, Part 50
(10 CFR Part 50, Appendix G), requires that pressure-temperature (P-T)
limits be established for reactor pressure vessels (RPVs) during normal
operating and hydrostatic or leak rate testing conditions.
Specifically, 10 CFR Part 50, Appendix G, states, ``The appropriate
requirements on both the pressure-temperature limits and the minimum
permissible temperature must be met for all conditions.'' Appendix G of
10 CFR Part 50 specifies that the requirements for these limits are the
American Society of Mechanical Engineers Boiler and Pressure Vessel
Code (ASME Code), Section XI, Appendix G, limits.
To address provisions of amendments to the technical
specifications' P-T limits, the licensee requested in its submittal
dated May 15, 2000, as supplemented May 19, 2000, that the staff exempt
Limerick Unit 1 from application of specific requirements of 10 CFR
Part 50, Section 50.60(a) and Appendix G, and substitute use of ASME
Code Cases N-588 and N-640. Code Case N-588 permits the postulation of
a circumferentially-oriented flaw (in lieu of an axially-oriented flaw)
for the evaluation of the circumferential welds in RPV P-T limit
curves. Code Case N-640 permits the use of an alternate reference
fracture toughness (KIC fracture toughness curve instead of
KIA fracture toughness curve) for reactor vessel materials
in determining the P-T limits. Since the pressure stresses on a
circumferentially-oriented flaw are lower than the pressure stresses on
an axially-oriented flaw by a factor of two, using Code Case N-588 for
establishing the P-T limits would be less conservative than the
methodology currently endorsed by 10 CFR Part 50, Appendix G, and
therefore, an exemption to apply the Code Case would be required by 10
CFR 50.60. Likewise, since the KIC fracture toughness curve
shown in ASME Code, Section XI, Appendix A, Figure A-2200-1 (the
KIC fracture toughness curve) provides greater allowable
fracture toughness than the corresponding KIA fracture
toughness curve of ASME Code, Section XI, Appendix G, Figure G-2210-1
(the KIA fracture toughness curve), using Code Case N-640
for establishing the P-T limits would be less conservative than the
methodology currently endorsed by 10 CFR Part 50, Appendix G, and
therefore, an exemption to 10 CFR 50.60 to apply the Code Case would
also be required.
The proposed action is in accordance with the licensee's
application for exemption dated May 15, 2000, as supplemented May 19,
2000.
The Need for the Proposed Action
ASME Code Case N-640 is needed to revise the method used to
determine the reactor coolant system (RCS) P-T limits, since continued
use of the present curves unnecessarily restricts the P-T operating
window. Since the RCS P-T operating window is defined by the P-T
operating and test limit curves developed in accordance with the ASME
Code, Section XI, Appendix G, procedure, continued operation of
Limerick Unit 1 with these P-T curves without the relief provided by
ASME Code Case N-640 would unnecessarily require the RPV to maintain a
temperature exceeding 212 deg.F in a limited operating window during
the pressure test. Consequently, steam vapor hazards would continue to
be one of the safety concerns for personnel conducting inspections in
primary containment. Implementation of the proposed P-T curves, as
allowed by ASME Code Case N-640, does not significantly reduce the
margin of safety and would eliminate steam vapor hazards by allowing
inspections in primary containment to be conducted at a lower coolant
temperature.
ASME Code Case N-588 allows a licensee to postulate a
circumferential flaw in circumferential RPV welds in lieu of the axial
flaw that is normally assumed to be present by the ASME Code, Section
XI, Appendix G, analysis. The staff has determined that the assumption
of an axial flaw in a circumferential RPV shell weld would provide an
overly-conservative margin of safety on stress intensities resulting
from the operating pressure, and that postulation of a circumferential
flaw in the circumferential welds would continue to satisfy the margin
of safety of two required by Appendix G to Section XI of the ASME Code.
In the requests for exemptions to use Code Cases N-588 and N-640,
the staff has determined that, pursuant to 10 CFR 50.12(a)(2)(ii), the
underlying purpose of the regulation will continue to be served by the
implementation of these Code Cases.
Environmental Impacts of the Proposed Action
The NRC has completed its evaluation of the proposed action and
concludes that the exemption described above would provide an adequate
margin of safety against brittle failure of the Limerick Unit 1 RPV.
The proposed action will not significantly increase the probability
or consequences of accidents, no changes are being made in the types of
any effluents that may be released offsite, and there is no significant
increase in occupational or public radiation exposure. Therefore, there
are no significant radiological environmental impacts associated with
the proposed action.
With regard to potential nonradiological environmental impacts, the
proposed action does not involve any historic sites. It does not affect
nonradiological plant effluents and has no other environmental impacts.
Therefore, there are no significant nonradiological impacts associated
with the proposed action.
Accordingly, the NRC concludes that there are no significant
environmental impacts associated with the proposed action.
Alternatives to the Proposed Action
As an alternative to the proposed action, the staff considered
denial of the proposed action (i.e., the ``no-action'' alternative).
Denial of the application would result in no change in current
environmental impacts. The environmental impacts of the proposed action
and the alternative action are similar.
Alternative Use of Resources
This action does not involve the use of any resources not
previously considered in the Final Environmental
[[Page 54082]]
Statement for the Limerick Generating Station, Units 1and 2, dated
April 1984.
Agencies and Persons Consulted
In accordance with its stated policy, on August 7, 2000, the staff
consulted with the Pennsylvania State official, David Ney of the
Pennsylvania Department of Environmental Protection, regarding the
environmental impact of the proposed action. The State official had no
comments.
Finding of No Significant Impact
On the basis of the environmental assessment, the NRC concludes
that the proposed action will not have a significant effect on the
quality of the human environment. Accordingly, the NRC has determined
not to prepare an environmental impact statement for the proposed
action.
For further details with respect to the proposed action, see the
licensee's letter dated May 15, 2000, as supplemented by letter dated
May 19, 2000, which are available for public inspection at the NRC
Public Document Room, The Gelman Building, 2120 L Street, NW.,
Washington, DC. Publicly available records will be accessible
electronically from the ADAMS Public Library component on the NRC Web
site, http://www.nrc.gov (the Electronic Reading Room).
Dated at Rockville, Maryland, this 29th day of August, 2000.
For The Nuclear Regulatory Commission.
Bartholomew C. Buckley,
Sr. Project Manager, Section 2, Project Directorate I, Division of
Licensing Project Management, Office of Nuclear Reactor Regulation.
[FR Doc. 00-22781 Filed 9-5-00; 8:45 am]
BILLING CODE 7590-01-P