ML19273B658
| ML19273B658 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 05/03/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19273B653 | List: |
| References | |
| NUDOCS 7906120101 | |
| Download: ML19273B658 (2) | |
Text
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a SAFETY EVALUATION MODIF_ICATIO_N TO SAFETY INJECTION ACTUATION __ SYSTEM PRAIRIE ISLAND UNITS 1 AND 2
_IJNTRODUCTION I.
T The licensee, Northern States Power Company, in its sub..ittal of April 26, 1979, proposed certain modifications to the safety injection actuation system logics for Units 1 and 2 in response to Item 3 of IE Bulletin 79-06A dated April 14, 1979.
II.
EVALUATION Since the date of licensing until the issuance of IE Bulletin 79-06A, safety injection was initiated, in addition to other parameters, from a coincident trip of 1/3 matched pairs of low pressurizer level and low pressurizer pressure.
Item 3 of IE Bulletin 79-06A directed all facilities using pressurizer water level coincident with pressurizer pressure for automatic initiation of safety injection to trip the low pressurizer level setpoint bistables so that when pressurizer pressure reaches the low setpoint, safety injection would be initiated regard-less of the pressurizer level. This change was ccmpleted on April 27,1979 by the licensee.
Bectuse of the concern that this action has resulted in placing Prairie Island Units 1 and 2 in a condi;icn which is more susceptible to spurious actuation of the safety injection system, the licensee has proposed the following modifications and Technical Specification changes to correct this situation!
The proposed modification to the safety injection actuation system entails removing the pressurizer level signal from each of the pressurizer level / pressure channel trip and converting the system to a two-out-of-three pressurizer low pressure trip. The instrumentation logic takes pressurizer pressure signals from three pressure transmitters and initiates a safety injection actuation whenever two of the three signals reach the low pressure setpoint of 1815 psig.
These modifica-tiens will satisfy the requirements of IEEE 279-1971, and other standards of installation required during the plant construction stage. We find these modifications acceptable.
2350 166 7 9 0 6120 lo t
. The proposed Technical Specifications (TS) change the discussion in the basis Sections of TS 3.5-2 and TS 3.5-3, and revise Item 3 of Table 3.5-1 and Item 1 of Table 3.5-3 to specify automatic safety injection actuation on a two-out-of-three pressurizer low pressure of 1815 psig. We find the changes to the Technical Specifi-cations to be acceptable.
Based on our review of the licensee's submittal, we conclude that the modifications to the safety injection actuation system logic satisfy the requirements of IEEE 279-1971 and that the associated Technical Specifications are correct; and therefore, are acceptable.
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