ML17212B347

Technical Evaluation of Response to Position 5 of Item II.E.4.2 of NUREG-0737 Containment Isolation Setpoint for St Lucie Nuclear Power Plant Unit 1 (Docket 50-335).

ML17212B347
Person / Time
Site:	Saint Lucie
Issue date:	05/31/1981
From:	Wade W LAWRENCE LIVERMORE NATIONAL LABORATORY
To:	Office of Nuclear Reactor Regulation
Shared Package
ML17212B345	List: ML17212B347
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.E.4.2, TASK-TM SRO-272, NUDOCS 8202030057
Download: ML17212B347 (2)

Text

INTRODUCTION AND BACKGROUND As a consequence of the incident at THI-2, implementatioq of .a number of new requirements has been recomaended for operating reactors.

These new requirements are described in NUREG-0660, "NRC Action Plan Devel'-

oped as a Result of the THI-2 Accident,"- Hay 1980, and NUREG-0737, of TNI Action Plan Requirements'," November 1980. The NRC staff"Clari-'ication has also requested licensees to submit information sufficient to permit an independent evaluation of their response to these new requirements. This report provides an'valuation of the response to Action Plan Item II.E.4.2,

'osition 5, by the designated licensee.=

DESIGN BASIS OR REVIEM CRITERIA Position 5 requires that the containment pressure setpoint that initiates containment isol'ation for non-essential system containment vessel penetrations be at, or reduced to, "...the minimum compatible with normal operating conditions."

TECHNICAL EVALUATION Response evaluation is based upon the values provided for the fol 1 owing par'ameters:

(1) The maximum observed or'xpected containment pressure during normal operation.

(2) The 'loop error- and observed drift in tne pressure sensing instrumentation providing the isolation signal

'- (see note).

'(3) The containment isolation pressure setpoint.

NOTE: The clarification document (NUREG-0737) provided only the expected margin for instrument error and did not specify acceptable values for instrument drift or atmospheric changes contributing to the total sensing loop error. Additional staff guidance established a limit of 3.0 psi for an isolation setpoint margin over .

the normal containment pressure to'ccount for total loop 'error.. In addition, for subatmospheric contairr-ments, a 3.0 psi setpoint margin over atmospheric pressure is also considered acceptable.

In consideration of these values, the isolation pressure setpoint is to be as low as practical without increasing .the probability of inadver-tent activation of the isolation signal.

CONCLUSIONS

/

The letter. of April 9, 1981, submitted by Florida Power and Light Company, provided sufficient information to conclude that the containment isolation pressure setpoint for St. Lucie Nuclear Power Plant, Unit 1, meets the NUREG-0660/0737 requirements and is within the additional limit,-

ing guidelines provided by the NRC staff.

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