ML023510312
| ML023510312 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/17/2002 |
| From: | Shukla G NRC/NRR/DLPM/LPD4 |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| TAC MB6760, TAC MB6761 | |
| Download: ML023510312 (4) | |
Text
December 17, 2002 MEMORANDUM TO: Biweekly Notice Coordinator FROM:
Girija S. Shukla, Project Manager, Section 2
/RA/
Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation
SUBJECT:
REQUEST FOR PUBLICATION IN BIWEEKLY FR NOTICE -
NOTICE OF CONSIDERATION OF ISSUANCE OF AMENDMENTS TO FACILITY OPERATING LICENSES, PROPOSED NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION, AND OPPORTUNITY FOR A HEARING (TAC NOS. MB6760 AND MB6761)
Pacific Gas and Electric Company, Docket Nos. 50-275 and 50-323, Diablo Canyon Nuclear Power Plant, Unit Nos. 1 and 2, San Luis Obispo County, California Date of amendment requests: August 27, 2002 Description of amendment requests: The proposed license amendments would revise the term "minimum measured flow per loop" to "measured loop flow" in the allowable value and nominal trip setpoint for the Reactor Coolant Flow-Low reactor trip function contained in Table 3.3.1-1, "Reactor Trip System Instrumentation," of Technical Specification (TS) 3.3.1.
In addition, the proposed amendments would allow for an alternate method for the measurement of reactor coolant system (RCS) total volumetric flow rate through measurement of the elbow tap differential pressures on the RCS primary cold legs. The use of elbow tap differential pressures normalized to Diablo Canyon Power Plant Cycle 1 and 2 precision flow calorimetrics would improve the accuracy of the RCS flow measurement through reduction of the effect of hot leg temperature streaming that is present in the current flow calorimetric method.
Biweekly Notice Coordinator Basis for proposed no significant hazards consideration determination: As required by 10 CFR 50.91(a), the licensee has provided its analysis of the issue of no significant hazards consideration, which is presented below:
1.
The proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
The proposed change revises the Technical Specification (TS) 3.3.1 Table 3.3.1-1 term "minimum measured flow per loop" to "measured loop flow" in the allowable value and nominal trip setpoint for the Reactor Coolant Flow-Low reactor trip function and allows an alternate method for the measurement of reactor coolant system (RCS) total flow to meet TS surveillance requirement (SR) SR 3.4.1.4 through measurement of the elbow tap differential pressures on the RCS primary cold legs.
The change will not increase the probability of an accident previously evaluated because adequate RCS flow will still be assured. The Reactor Coolant Flow-Low reactor trip function allowable value and nominal trip setpoint are accident mitigation functions and are not an accident initiator.
The elbow tap method to measure RCS flow and the change to the flow definition associated with the Reactor Coolant Flow-Low reactor trip function do not involve a plant modification.
For the elbow tap method to measure RCS flow, sufficient margin exists to account for all reasonable instrument uncertainties and therefore the RCS flow will continue to be maintained at a value which is bounded by the design basis accident initial conditions. The change to the flow definition associated with the Reactor Coolant Flow-Low reactor trip function allowable value and nominal trip setpoint does not change a design basis accident initial condition or the conditions at the time of reactor trip during a design basis accident and therefore has no adverse effect on the design basis accidents which credit the Reactor Coolant Flow-Low reactor trip setpoint.
Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
2.
The proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.
The proposed change to the flow definition associated with the Reactor Coolant Flow-Low reactor trip function allowable value and nominal trip setpoint and the proposed elbow tap method to measure RCS flow will not create the possibility of a new or different type of accident from any previously evaluated. There are no physical changes being made to the plant and there are no changes in operation of the plant that could introduce a new failure mode, creating an accident which has not been evaluated.
Biweekly Notice Coordinator Therefore, the proposed change does not create the possibility of a new or different accident from any accident previously evaluated.
3.
The proposed change does not involve a significant reduction in a margin of safety.
The proposed change to the flow definition associated with the Reactor Coolant Flow-Low reactor trip function allowable value and nominal trip setpoint and the proposed elbow tap method to measure RCS flow will not reduce the margin of safety. For the proposed elbow tap flow method, sufficient margin exists to account for all reasonable instrument uncertainties and thus the RCS flow will continue to be maintained at a value which is bounded by the design basis accident initial conditions, and no adverse effect on the plant response to design basis accidents is created. The change in the flow definition associated with the Reactor Coolant Flow-Low reactor trip function allowable value and nominal trip setpoint does not change a design basis accident initial condition or the conditions at the time of reactor trip during a design basis accident, and therefore has no effect on the plant response to design basis accidents which credit the Reactor Coolant Flow-Low reactor trip setpoint. Since the change does not affect the response to design basis accidents, it does not result in a decrease in departure from nucleate boiling margin or reactor coolant system peak pressure margin for the design basis accidents.
Therefore, the proposed change does not involve a significant reduction in a margin of safety.
The NRC staff has reviewed the licensees analysis and, based on this review, it appears that the three standards of 10 CFR 50.92(c) are satisfied. Therefore, the NRC staff proposes to determine that the amendment requests involve no significant hazards consideration.
Attorney for licensee: Christopher J. Warner, Esq., Pacific Gas and Electric Company, P.O. Box 7442, San Francisco, California 94120 NRC Section Chief: Stephen Dembek
ML023510312 NRR-041 OFFICE PDIV-2/PM PDIV-2/LA PDIV-2/SC NAME GShukla:rkb EPeyton SDembek DATE 12/16/02 12/13/02 12/16/02 DOCUMENT NAME: G:\\PDIV-2/DiabloCanyon/bwn MB6760-61.wpd