[Federal Register Volume 63, Number 82 (Wednesday, April 29, 1998)]
[Notices]
[Pages 23477-23478]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-11339]
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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-282 and 50-306]
Northern States Power Company (Prairie Island Nuclear Generating
Plant, Units 1 and 2); Environmental Assessment and Finding of No
Significant Impact
The U.S. Nuclear Regulatory Commission (the Commission) is
considering issuance of an exemption from certain requirements of its
regulations to Facility Operating License Nos. DPR-42 and DPR-60,
issued to Northern States Power Company (NSP or the licensee), for
operation of Prairie Island Nuclear Generating Plant, Units 1 and 2,
located in Goodhue County, Minnesota.
Environmental Assessment
Identification of the Proposed Action
The proposed action would permit the licensee to use American
Society of Mechanical Engineers (ASME) Code Case N-514 for setting the
pressure setpoint of each unit's overpressure protection system (OPPS)
so that the pressure-temperature (P-T) limits required by 10 CFR Part
50, Appendix G, could be exceeded by 10 percent during a low
temperature pressure transient. By application dated March 6, 1998, the
licensee requested an exemption from certain requirements of 10 CFR
50.60, ``Acceptance Criteria for Fracture Prevention Measures for
Lightwater Nuclear Power Reactors for Normal Operation,'' and 10 CFR
Part 50, Appendix G, ``Fracture Toughness Requirements.''
The Need for the Proposed Action
Pursuant to 10 CFR 50.60, all lightwater nuclear power reactors
must meet the fracture toughness requirements for the reactor coolant
pressure boundary as set forth in 10 CFR Part 50, Appendix G. Appendix
G of 10 CFR Part 50 defines P-T limits during any condition of normal
operation, including anticipated operational occurrences and system
hydrostatic tests to which the pressure boundary may be subjected over
its service lifetime, and specifies that these P-T limits must be at
least as conservative as the limits obtained by following the methods
of analysis and the margins of safety of the ASME Code, Section XI,
Appendix G.
By letter dated March 6, 1998, NSP submitted an exemption request
to enable the use of ASME Code Case N-514 as an alternative method for
determining the OPPS setpoint. NSP
[[Page 23478]]
determined that the exemption request from the provisions of 10 CFR
50.60 and Appendix G was necessary since these regulations require, as
noted above, that the reactor vessel conditions not exceed the P-T
limits established by Appendix G. In referring to 10 CFR 50.12 on
specific exemptions, NSP cited special circumstances as stated in 10
CFR 50.12(a)(2)(ii) on achieving the underlying purpose of the
regulations as its basis for requesting this exemption.
The underlying purpose of 10 CFR Part 50, Appendix G, is to
establish fracture toughness requirements for the reactor coolant
system (RCS) pressure boundary to provide adequate margins of safety
during any condition of normal operation. The OPPS provides a physical
means of protecting these limits. NSP proposed that establishing the
OPPS pressure setpoint per the N-514 provisions such that the vessel
pressure would not exceed 110 percent of the P-T limit allowables would
still provide an acceptable level of safety and mitigate the potential
for an inadvertent actuation of the OPPS.
The plant operators must operate the plant in a pressure window
that is between the minimum pressure required to preserve reactor
coolant pump seals and at a maximum pressure that does not challenge
the power-operated relief valve setpoint. Without the application of
ASME Code Case N-514, Prairie Island would have an operating window
that is too narrow to permit reasonable system makeup and pressure
control. Further reduction of the OPPS setpoint below 500 psig would
increase the probability that the reactor coolant pumps' no. 1 seal
will fail as a result of OPPS operation, and that such a seal failure
could produce a breach in the RCS boundary that could not be isolated.
Therefore, inadvertent OPPS actuation could lead to a small break loss-
of-coolant accident and the unnecessary release of reactor coolant
inside containment.
Environmental Impacts of the Proposed Action
The Commission has completed its evaluation of the proposed action
and concludes that the proposed action involves features located
entirely within the protected areas as defined in 10 CFR Part 20.
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 offsite, and there is no significant
increase in the allowable individual or cumulative occupational
radiation exposure. Accordingly, the Commission concludes that there
are no significant radiological environmental impacts associated with
the proposed action.
With regard to potential nonradiological impacts, the proposed
action does involve features located entirely within the restricted
area as defined in 10 CFR Part 20. It does not affect nonradiological
plant effluents and has no other environmental impact. Accordingly, the
Commission concludes that there are no significant nonradiological
environmental impacts associated with the proposed action.
Alternative to the Proposed Action
Since the Commission has concluded there is no measurable
environmental impact associated with the proposed action, any
alternatives with equal or greater environmental impact need not be
evaluated. As an alternative to the proposed action, the staff
considered denial of the proposed action. 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
Prairie Island Nuclear Generating Plant.
Agencies ad Persons Consulted
In accordance with its stated policy, on April 7, 1998, the staff
consulted with the Minnesota State official, Mike McCarthy of the
Department of Public Service, regarding the environmental impact of the
proposed action. The state official had no comments.
Finding of No Significant Impact
Based upon the environmental assessment, the Commission concludes
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 March 6, 1998, 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 Minneapolis Public Library, Technology and
Science Department, 300 Nicollet Mall, Minneapolis, Minnesota 55401.
Dated at Rockville, Maryland, this 23rd day of April, 1998.
For the Nuclear Regulatory Commission.
Cynthia A. Carpenter,
Director, Project Directorate III-1, Division of Reactor Projects--III/
IV, Office of Nuclear Reactor Regulation.
[FR Doc. 98-11339 Filed 4-28-98; 8:45 am]
BILLING CODE 7590-01-P
