[Federal Register Volume 64, Number 84 (Monday, May 3, 1999)]
[Notices]
[Pages 23688-23689]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-11117]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-275 and 50-323]
Pacific Gas and Electric Company; Diablo Canyon Power Plant,
Units 1 and 2; Environmental Assessment and Finding of No Significant
Impact
The U.S. Nuclear Regulatory Commission (the Commission) is
considering the issuance of an exemption from certain requirements of
its regulations for Facility Operating License Nos. DPR-80 and DPR-82
that were issued to Pacific Gas and Electric Company (the licensee) for
operation of the Diablo Canyon Power Plant (DCPP) Units 1 and 2,
located in San Luis Obispo County, California.
Environmental Assessment
Identification of the Proposed Action
The proposed action would exempt Pacific Gas and Electric Company
(PG&E) from the requirements of 10 CFR 50.60 and 10 CFR Part 50,
Appendix G, to allow use of the American Society of Mechanical
Engineers (ASME) Code Case N-514 as an alternate method for
establishing the setpoints for the low temperature overpressure
protection (LTOP) systems that have been installed for overpressure
protection of the DCPP reactor coolant pressure boundary.
The proposed action is in accordance with the licensee's
application for exemption dated September 3, 1998, as supplemented by
letters dated January 22, February 5, and March 17, 1999.
The Need for the Proposed Action
The provisions of 10 CFR 50.60 and 10 CFR Part 50, Appendix G,
restrict the operating conditions for the DCPP reactor coolant systems
from exceeding the pressure/temperature (P/T) limits established in
compliance with Appendix G to Section XI of the ASME Boiler and
Pressure Vessel Code. The requirements in 10 CFR Part 50 were
established to protect the integrity of the reactor coolant pressure
boundary in nuclear power plants. As part of these requirements, 10 CFR
Part 50, Appendix G, requires that the P/T limits be established for
reactor pressure vessels during normal and hydrostatic or leak rate
testing conditions. Specifically, 10 CFR Part 50, Appendix G, states
that ``The appropriate requirements on . . . the pressure-temperature
limits and minimum permissible temperature must be met for all
conditions.'' Pressurized water reactor licensees have installed cold
overpressure mitigation systems(COMS)/low temperature overpressure
protection systems (LTOP) in order to protect the reactor coolant
pressure boundaries from being operated outside of the boundaries
established by the P/T limit curves and to provide pressure relief of
the reactor coolant pressure boundaries during low temperature
overpressurization events. DCPP technical specifications require them
to update and submit the changes to its LTOP setpoints whenever PG&E is
requesting approval for amendments to the P/T limit curves. The use of
Code Case N-514 would provide an acceptable level of safety against
overpressurization events of the DCPP reactor pressure vessels. Based
on the conservatism that is incorporated into the methods of Appendix G
of the Section XI to the ASME Code for calculating P/T limit curves, it
is concluded that permitting the LTOP setpoints to be established in
accordance with the Code Case (e.g., at a level 110 percent
of the limit defined by the P/T limit curves) would provide an adequate
margin of safety against brittle fracture failure of the reactor
pressure vessels. Therefore, the requirements of 10 CFR Part 50,
Appendix G and Appendix G to Section XI of the ASME Code, are not
necessary
[[Page 23689]]
to prevent brittle fracture of the reactor pressure vessel from
occurring during low temperature operation.
Environmental Impacts of the Proposed Action
The Commission has completed its evaluation of the proposed action
and concludes that the use of Code Case N-514 as an alternative method
for establishing the setpoints for the LTOP systems at DCPP Units 1 and
2 would provide an adequate margin of safety against brittle fracture
of the DCPP reactor vessels.
The proposed action will not increase the probability or
consequences of accidents, no changes are being made in the types of
any effluents that may be released off site, 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 non-radiological impacts, the proposed
action does not involve any historic sites. It does not affect non-
radiological plant effluents and has no other environmental impact.
Therefore, there are no significant non-radiological environmental
impacts associated with the proposed action.
Accordingly, the Commission 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 Statement for Diablo
Canyon Power Plant dated May 1973, and the Addendum dated May 1976.
Agencies and Persons Consulted
In accordance with its stated policy, on April 22, 1999, the staff
consulted with the California State official, Mr. Steve Hsu of the
Radiologic Health Branch of the State Department of Health Services,
regarding the environmental impact of the proposed amendments. The
State official had no comments.
Finding of No Significant Impact
On the basis of the environmental assessment, the Commission
concludes that the proposed amendments will not have a significant
effect on the quality of the human environment. Accordingly, the
Commission 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 application dated September 3, 1998, as supplemented dated
January 22, February 5, and March 17, 1999, which are available for
public inspection at the Commission's Public Document Room, The Gelman
Building, 2120 L Street, NW., Washington, DC, and at the local public
document room located at the California Polytechnic State University,
Robert E. Kennedy Library, Government Documents and Maps Department,
San Luis Obispo, California 93407.
Dated at Rockville, Maryland, this 28th day of April 1999.
For the Nuclear Regulatory Commission.
Steven D. Bloom,
Project Manager, Section 2, Project Directorate IV & Decommissioning,
Division of Licensing Project Management, Office of Nuclear Reactor
Regulation.
[FR Doc. 99-11117 Filed 4-30-99; 8:45 am]
BILLING CODE 7590-01-P
