[Federal Register Volume 60, Number 206 (Wednesday, October 25, 1995)]
[Notices]
[Pages 54710-54711]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-26420]



-----------------------------------------------------------------------

NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-280 and 50-281]


Virginia Electric and Power Company; Surry Power Station, 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-32 and DPR-37, 
issued to Virginia Electric and Power Company, (the licensee), for 
operation of the Surry Power Station, Units 1 and 2 located in Surry 
County, Virginia.

Environmental Assessment

Identification of Proposed Action

    The proposed action would grant an exemption from certain 
requirements of 10 CFR 50.60, ``Acceptance Criteria for Fracture 
Prevention Measures for Light-Water Nuclear Power Reactors for Normal 
Operation,'' to allow application of an alternate methodology to 
determine the low temperature overpressure protection (LTOP) setpoint 
for the Surry Power Station, Units 1 and 2. The proposed alternate 
methodology is consistent with guidelines developed by the American 
Society of Mechanical Engineers (ASME) Working Group on Operating Plant 
Criteria (WGOPC) to define pressure limits during LTOP events that 
avoid certain unnecessary operational restrictions, provide adequate 
margins against failure of the reactor pressure vessel, and reduce the 
potential for unnecessary activation of pressure-relieving devices used 
for LTOP. These guidelines have been incorporated into Code Case N-514, 
``Low Temperature Overpressure Protection,'' which has been approved by 
the ASME Code Committee. The content of this code case has been 
incorporated into Appendix G of Section XI of the ASME Code and 
published in the 1993 Addenda to Section XI.
    The philosophy used to develop Code Case N-514 guidelines is to 
ensure that the LTOP limits are still below the pressure/temperature 
(P/T) limits for normal operation, but allow the pressure that may 
occur with activation of pressure-relieving devices to exceed the P/T 
limits, provided acceptable margins are maintained during these events. 
This philosophy protects the pressure vessel from LTOP events, and 
still maintains the Technical Specification P/T limits applicable for 
normal heatup and cooldown in accordance with Appendix G to 10 CFR Part 
50 and Sections III and XI of the ASME Code.

The Need for the Proposed Action

    Pursuant to 10 CFR 50.60, all light-water nuclear power reactors 
must meet the fracture toughness and material surveillance program 
requirements for the reactor coolant pressure boundary as set forth in 
Appendices G and H to 10 CFR Part 50. Appendix G to 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. 
It is specified in 10 CFR 50.60(b) that alternatives to the described 
requirements in Appendices G and H to 10 CFR Part 50 may be used when 
an exemption is granted by the Commission under 10 CFR 50.12.
    To prevent transients that would produce pressure excursions 
exceeding the Appendix G P/T limits while the reactor is operating at 
low temperatures, the licensee installed an LTOP system. The LTOP 
system includes pressure relieving devices in the form of Power-
Operated Relief Valves (PORVs) that are set at a pressure low enough 
that if a transient occurred while the coolant temperature is below the 
LTOP enabling temperature, they would prevent the pressure in the 
reactor vessel from exceeding the Appendix G P/T limits. To prevent 
these valves from lifting as a result of normal operating pressure 
surges (e.g., reactor coolant pump starting, and shifting operating 
charging pumps) with the reactor coolant system in a water solid 
condition, the operating pressure must be maintained below the PORV 
setpoint.
    The reactor coolant system pressure/temperature operating window at 
low temperatures is defined by the LTOP setpoint. Minimal operating 
margin is available between the LTOP setpoint and the pressure 
experienced at low temperatures due to the startup of a reactor coolant 
pump, or as a result of normal operating pressure surges with the 
reactor coolant system in a water solid condition. Implementation of a 
LTOP setpoint that is valid from 15 EFPY to the end-of-license without 
the additional margin allowed by ASME Code Case N-514 would restrict 
the pressure/temperature operating window and would potentially result 
in undesired PORV lifts. Therefore, the licensee proposed that in 
determining the PORV setpoint for LTOP events for Surry, the allowable 
pressure be determined using the safety margins developed in an 
alternate methodology in lieu of the safety margins required by 
Appendix G to 10 CFR Part 50. The alternate methodology is consistent 
with ASME Code Case N-514. The content of this code case has been 
incorporated into Appendix G of Section XI of the ASME Code and 
published in the 1993 Addenda to Section XI.
    An exemption from 10 CFR 50.60 is required to use the alternate 
methodology for calculating the maximum allowable pressure for LTOP 
considerations. By application dated June 8, 1995, the licensee 
requested an exemption from 10 CFR 50.60.

Environmental Impacts of the Proposed Action

    The Commission has completed its evaluation of the proposed action.
    Appendix G of the ASME Code requires that the P/T limits be 
calculated: (a) using a safety factor of 2 on the principal membrane 
(pressure) stresses, (b) assuming a flaw at the surface with a depth of 
one-quarter (1/4) of the vessel wall thickness and a length of six (6) 
times its depth, and (c) using a conservative fracture toughness curve 
that is based on the lower bound of static, dynamic, and crack arrest 
fracture toughness tests on material similar to the Surry reactor 
vessel material.
    In determining the PORV setpoint for LTOP events, the licensee 
proposed to use safety margins based on an alternate methodology 
consistent with the proposed ASME Code Case N-514 guidelines. The ASME 
Code Case N-514 allows determination of the setpoint for LTOP events 
such that the maximum pressure in the vessel would not exceed 110% of 
the P/T limits of the existing ASME Appendix G.
    The change 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 non-radiological impacts, the proposed 
change involves use of a lower safety margin on fracture toughness for 

[[Page 54711]]
determining the PORV setpoint during LTOP events; but reduces the 
potential for activation of pressure relieving devices, thereby 
improving plant safety. It does not affect non-radiological plant 
effluents and has no other environmental impact. Therefore, the 
Commission concludes that there are no significant non-radiological 
environmental impacts associated with the proposed action.

Alternatives 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 
Surry Power Station, Units 1 and 2.

Agencies and Persons Consulted

    In accordance with its stated policy, on October 13, 1995, the 
staff consulted with the Virginia State official, Mr. Foldesi of the 
State Health Department, 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 June 8, 1995, 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 Swem Library, College of William and Mary, 
Williamsburg, Virginia 23185.

    Dated at Rockville, Maryland, this 18th day of October 1995.

For the Nuclear Regulatory Commission
David B. Matthews,
Director, Project Directorate II-1, Division of Reactor Projects--I/II, 
Office of Nuclear Reactor Regulation.
[FR Doc. 95-26420 Filed 10-24-95; 8:45 am]
BILLING CODE 7590-01-P