[Federal Register Volume 60, Number 27 (Thursday, February 9, 1995)]
[Notices]
[Pages 7804-7805]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-3366]



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NUCLEAR REGULATORY COMMISSION

Public Service Electric and Gas Company; Environmental Assessment 
and Finding of No Significant Impact

[Docket Nos. 50-272 and 50-311]
    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-70 and DPR-75, 
issued to the Public Service Electric and Gas Company, PECO Energy 
Company, Delmarva Power and Light Company, and Atlantic City Electric 
Company, licensees for the Salem Nuclear Generating Station, Units 1 
and 2. The plants are located at the licensee's site in Salem County, 
New Jersey. The exemption was requested by the licensee by letter dated 
December 22, 1994.

Environmental Assessment

Identification of Proposed Action

    The proposed action requests 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 Salem 
Nuclear Generating 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 Specifications 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.
    In addition, in order to prevent cavitation of a reactor coolant 
pump, the operator must maintain a differential pressure across the 
reactor coolant pump seals. Hence, the licensee must operate the plant 
in a pressure window that is defined as the difference between the 
minimum required pressure to start a reactor coolant pump and the 
operating margin to prevent lifting of the PORVs due to normal 
operating pressure surges. The licensee's current LTOP analysis, which 
removes the non-conservatism in a previous analysis by assuming one 
reactor coolant pump in operation, indicates that using the Appendix G 
safety margin to determine the PORV setpoint would result in a new 
pressure setpoint within the current operating window of Salem 1 and a 
new setpoint just outside the current operating window of Salem 2. In 
both cases, there would be no margin for normal operating pressure 
surges. Operating with these limits could result in the lifting of the 
PORVs and cavitation of the reactor coolant pumps during normal 
operation. Therefore, the licensee proposed that in determining the 
PORV setpoint for LTOP events for Salem, 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 December 22, 1994, 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 Salem 
reactor vessel material.
    In determining the PORV setpoint for LTOP events, the licensee 
proposed to [[Page 7805]] 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. This results in a safety factor of 1.8 on the principal membrane 
stresses. All other factors, including assumed flaw size and fracture 
toughness, remain the same. Although this methodology would reduce the 
safety factor on the principal membrane stresses, use of the proposed 
criteria will provide adequate margins of safety to the reactor vessel 
during LTOP transients.
    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 occupation radiation exposure.
    Accordingly, the Commission concludes that this proposed action 
would result in no significant radiological environmental impact.
    With regard to potential non-radiological impacts, the proposed 
change involves use of more realistic safety margins for determining 
the PORV setpoint during LTOP events. 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.

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 to 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 
equivalent.

Alternative Use of Resources

    This action did not involve the use of any resources not previously 
considered in the Final Environmental Statements related to operation 
of the Salem Nuclear Generating Station, dated April 1973.

Agencies and Persons Consulted

    The NRC staff consulted with the state of Pennsylvania regarding 
the environmental impact of the proposed action. The state official had 
no comments.

Finding of No Significant Impact

    The Commission has determined not to prepare an environmental 
impact statement for the proposed exemption.
    Based upon the foregoing environmental assessment, the Commission 
concludes that the proposed action will not have a significant effect 
on the quality of the human environment.
    For further details with respect to this action, see the request 
for exemption dated December 22, 1994, which is available for public 
inspection at the Commission's Public Document Room, 2120 L Street, 
NW., Washington, DC and at the local public document room located at 
the Salem Free Public Library, 112 West Broadway, Salem, New Jersey 
08079.

    Dated at Rockville, Maryland, this 7th day of February 1995.

    For The Nuclear Regulatory Commission.
Chester Poslusny,
Acting Director, Project Directorate I-2, Division of Reactor 
Projects--I/II, Office of Nuclear Reactor Regulation.
[FR Doc. 95-3366 Filed 2-8-95; 8:45 am]
BILLING CODE 7590-01-M