05000280/LER-1980-033-01, /01T-0:on 800530,assumed Value for Spray Nozzle Thermal Effectiveness for Outside Recirculation Spray Sys Was Less Conservative than Assumed in NPSH Mod Analysis. Caused by Error in NPSH Calculations

/01T-0:on 800530,assumed Value for Spray Nozzle Thermal Effectiveness for Outside Recirculation Spray Sys Was Less Conservative than Assumed in NPSH Mod Analysis. Caused by Error in NPSH Calculations

ML18139A331
Person / Time
Site:	Surry
Issue date:	06/12/1980
From:	Joshua Wilson VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18139A330	List: 05000280/LER-1980-033, Fowards LER 80-033/01T-0 05000280/LER-1980-033-01, /01T-0:on 800530,assumed Value for Spray Nozzle Thermal Effectiveness for Outside Recirculation Spray Sys Was Less Conservative than Assumed in NPSH Mod Analysis. Caused by Error in NPSH Calculations
References
LER-80-033-01T, LER-80-33-1T, NUDOCS 8006180476
Download: ML18139A331 (2)

LER-1980-033, /01T-0:on 800530,assumed Value for Spray Nozzle Thermal Effectiveness for Outside Recirculation Spray Sys Was Less Conservative than Assumed in NPSH Mod Analysis. Caused by Error in NPSH Calculations

Event date:
Report date:
2801980033R01 - NRC Website

text

RC FORM 366~-

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U.S. NUCLEAR REGULA I UR t COIVIIYIISSIU!i AICENSEE EVENT REPORT

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(PLEASE PRINT OR TYPE. REQUIRED INFORMATION)

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° 10 I o I 6 I 1 I 2 I 8 I o 10 60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (,a)

!During steady state operation, it was'-aetermined that the assumed value for spray noz-zle thermal effectiveness for the Outside Recirc. Spray system was less conservative than assumed in the analysis for the interim NPSH modifications and the resulting Condi~

tion of License issued August 1978. This condition modified the basis for T.S.3.8. There-

]:JI] !fore, the containment internal air partial pressure and temperature may have been opera-1

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I ted in a manner that was less conservative than assumed in the revised_accident analysisr This is reportable per T.S.6.6.2.a.9. The health & safety of the public was unaffected.

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20 31 ACTION FUTURE EFFECT SHUTDOWN

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32 COMPONENT MANUFACTURER TAKEN ACTION ON PLANT METHOD HOURS ~ SUBMITTED FORM :;us.

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 43 44 47 1 1 I O I 1operation with containment temperature and air partial pressure in a non-conservative Lill] direction was caused by the error in the assumed spray thermal effectiveness value in [I))] !the NPSH report calculations performed for the interim NPSH modifications. AdministrativT I controls were instituted to assure operation within the new analysis.

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~kT~ACHMENT I (PAGE 1 OF 1)_.a.,

SURRY POWER STATION, UNIT ~l

.. DO.G1($T NO:

50-280 REPORT NO:

80-033/0lT-O EVENT DATE: 5-30-80 TITLE OF EVENT:

EXCESSIVE CONTAINMENT PRESSURE AND TEMPERATURE

1.

DESCRIPTION OF EVENT

During normal steady state operation, a non-conservative assumption in the interim NPSH analysis of the Outside Recirc. Spray Pumps (Unit 1) was identified that was less conservative than that in the analysis for the basis of T.S.3.8 as amended by the August 1978 Condition of License.

Therefore, the containment internal air partial pressure and temperature may have been operated in a manner that was less conservative than assumed in the revised accident analysis.

2.

PROBABLE CONSEQUENCES AND STATUS OF REDUNDANT SYSTEMS:

/

Implementation of a portion of the long term NPSH modifications have been recently completed during the Unit 1 outage to correct the reduced spray thermal effective-ness.

With the interim NPSH modification installed, certain temperature and air partial pressure conditions in the containment and certain service water tempera-tures~ the Outside Recirc. Spray Nozzle thermal effectiveness would have been less than assumed in the interim analysis if accident conditions had existed.

There-fore, the containment pressure transient could have been extended and require longer to return to and remain at sub-atmospheric conditions than determined by the revised accident analysis.

All equipment remained operational and the health and safety of the public was not affected.

3.

CAUSE

Due to NPSH considerations of the Unit 1 Outside Recirc. Spray pumps, flow was restricted.

This reduced the nozzle thermal effectiveness which was not taken into consideration in performing the interim NPSH analysis.

Initial analysis indicated that plant operation could continue with existing containment tempera-ture and pressure limits.

However, reanalysis indicated that more restrictive changes are needed for T.S. 3.8.

A request to change Technical Specification has been.submitted and administrative controls implemented to maintain proper tempera-ture pressure relationships.

4.

IMMEDIATE CORRECTIVE ACTION

Action was taken to implement administrative controls to assure containment air partial pressure and temperature are maintained within the limits of the proposed T.S. change.

5.

SUBSEQUENT CORRECTIVE ACTION:

None required.

6.

FUTURE CORRECTIVE ACTION:

The final design change has been completed on Unit 2 during the present outage and the balance of the final design change on Unit 1 will be completed during the next refueling.

These interim requirements will then not be required.

7.

GENERIC IMPLICATIONS:

None.