[Federal Register Volume 64, Number 144 (Wednesday, July 28, 1999)]
[Notices]
[Pages 40901-40903]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-19256]
-----------------------------------------------------------------------
NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-269, 50-270, and 50-287]
Duke Energy Corp.; Oconee Nuclear Station, Units 1, 2, and 3;
Environmental Assessment and Finding of No Significant Impact
The U.S. Nuclear Regulatory Commission (the Commission) is
[[Page 40902]]
considering issuance of an exemption from certain requirements of Title
10 of the Code of Federal Regulations (10 CFR) part 50, Sec. 50.60(a)
to the Duke Energy Corporation (the licensee) for operation of the
Oconee Nuclear Station, Units 1, 2, and 3, located in Seneca, Oconee
County, South Carolina.
Environmental Assessment
Identification of the Proposed Action
The proposed action would exempt the licensee from certain
provisions of 10 CFR part 50, Sec. 50.60(a) and 10 CFR part 50,
appendix G. The NRC has established requirements in 10 CFR part 50 to
protect the integrity of the reactor coolant pressure boundary (RCPB)
in nuclear power plants. As part of these requirements, 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 that ``[t]he
appropriate requirements * * * on pressure-temperature limits and
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 (ASME) Code,
Section XI, Appendix G limits.
Pressurized water reactor licensees have installed cold
overpressure mitigation systems/low temperature overpressure protection
(LTOP) systems in order to protect the RCPB from being operated outside
of the boundaries established by the P-T limit curves and to provide
pressure relief on the RCPB during low temperature overpressurization
events. The licensee is required by the Oconee Units 1, 2, and 3
Technical Specifications (TS) to update and submit the changes to its
LTOP setpoints whenever the licensee is requesting approval for
amendments to the P-T limit curves in the Oconee Unit 1, 2, and 3 TS.
Therefore, in order to address provisions of amendments to the TS
P-T limits and LTOP curves, the licensee requested in its submittal
dated May 11, 1999, that the staff exempt Oconee Units 1, 2, and 3 from
application of specific requirements of 10 CFR part 50, Sec. 50.60(a)
and 10 CFR part 50, appendix G, and substitute use of three ASME Code
Cases as follows:
1. N-514 as an alternate methodology for determining the low
temperature overpressure protection system enable temperature,
2. N-588 for determining the reactor vessel P-T limits derived from
postulating a circumferentially-oriented reference flaw in a
circumferential weld, and
3. N-626 as an alternate reference fracture toughness for reactor
vessel materials for use in determining the
P-T limits. (As a result of recent ASME code committee action, the
designation for Code Case N-626 was changed to
N-640. Therefore, Code Case N-640 will be discussed below rather than
Code Case N-626, the designation referenced in the submittal.)
The proposed action is in accordance with the licensee's
application for exemption contained in a submittal dated May 11, 1999,
and is needed to support the TS amendments that are contained in the
same submittal and are being processed separately. The proposed
amendments will revise the P-T limits of TS 3.4.3 for Oconee Units 1,
2, and 3 related to the heatup, cooldown, and inservice test
limitations for the Reactor Coolant System of each unit to a maximum of
33 Effective Full Power Years (EFPY). It will also revise TS 3.4.12,
Low Temperature Overpressure Protection System, to reflect the revised
P-T limits of the reactor vessels.
The Need for the Proposed Action
During staff review of this submittal, the staff determined that
granting of an exemption for the use of Code Case
N-514 was not necessary.
ASME Code Case N-588 and Code Case N-626 (which is now Code Case N-
640) are needed to revise the method used to determine the RCS P-T
limits, since continued use of the present curves unnecessarily
restricts the P-T operating window. Application of the code cases will,
therefore, relax the LTOP operating window and reduce potential
challenges to the reactor coolant system power operated relief valves.
In addition, the present restrictions require that, under certain low
temperature conditions, only one reactor coolant pump in a reactor
coolant loop may be operated. The licensee has found from experience
that the effect of this restriction is degradation of the reactor
coolant pump impellers from cavitation sustained when either one pump
or one pump in each loop is operating. Application of the Code Cases
will allow operation of two reactor coolant pumps in a single loop,
which will eliminate this condition.
In the associated exemption, 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 Commission 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 Oconee Units
1, 2, and 3 reactor vessels.
The proposed action will not increase the probability or
consequences of accidents, no changes are being made in the types or
amounts 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 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 the
Oconee Nuclear Station, Units 1, 2, and 3, dated March 1972.
Agencies and Persons Consulted
In accordance with its stated policy, on July 15, 1999, the staff
consulted with the South Carolina State official, Mr. Virgil Autry of
the Division of Radioactive Waste Management, Bureau of Land and Waste
Management, Department of Health and Environmental Control, 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 Commission
concludes
[[Page 40903]]
that the proposed action 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 letter dated May 11, 1999, which is 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 Oconee County Library, 501 West South
Street, Walhalla, South Carolina.
Dated at Rockville, MD, this 23rd day of July 1999.
For the Nuclear Regulatory Commission.
Richard L. Emch, Jr.,
Section Chief, Section 1, Project Directorate II, Division of Licensing
Project Management, Office of Nuclear Reactor Regulation.
[FR Doc. 99-19256 Filed 7-27-99; 8:45 am]
BILLING CODE 7590-01-P
