ML19338F768

Interim Deficiency Rept Re Centrifugal Charging Pump Operation Following Secondary Side High Energy Line Rupture.Design Changes Being Evaluated.Final Rept Will Be Provided in First Quarter 1981

ML19338F768
Person / Time
Site:	Wolf Creek, Callaway, Sterling
Issue date:	09/15/1980
From:	Petrick N STANDARDIZED NUCLEAR UNIT POWER PLANT SYSTEM
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19338F766	List: ML19338F768
References
10CFR-050.55E, 10CFR-50.55E, IEB-80-18, SLNRC-80-45, NUDOCS 8010270208
Download: ML19338F768 (2)

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6NUPPS Standardised Neeleer Unit l'ower Plant System 5 ' hoke Cherry Road Nicholas A.Petrick Ekvine, Maryland 20s50 Executive Director (30 J S064010 September 15, 1980 SLNRC 80-45 FILE: 0491.10.2 SUBJ: Centrifugal Charging Pump Operation Following Secondary Side High Energy Line Rupture Mr. Boyce Grier Director, Region I Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 Docket Nos.: STN 50-482, STN 50-483, STN 50-486 Ref.: 1. SLNRC 80-28, dated June 6,,1980, Same Subject

2. IE Bulletin No. 80-18, dated July 24, 1980

Dear Mr. Grier:

Reference 1 reported a potential deficiency involving the subject postu-lated transient. The letter also stated additional evaluation was re-quired to determine if the potential problem was applicable to the SNUPPS plants. Reference 2 addressed this same topic, but SNUPPS was not re-quired to respond to the Bulletin.

The analysis of this transient, using the calculational method provided by Westinghouse, has been completed for SNUPPS. The results indicate that the maximum and minimum developed heads for the centrifugal charging pumps are 2640 psi and 2516 psi, respectively. For both pumps to attain minimum flow by discharging into the reactor coolant system, the maximum system pressure is 2288 psig. The set pressure of the power-operated relief valves (PORVs) is 2350 psig. Therefore, even though the SNUPPS plants will have qualified PORVs, the problem described by the references is applicable to the SNUPPS plants.

Design changes that would correct this situation are being evaluated.

It is estimated that any such changes will not be completed until at least the first quarter of 1981. In addition, the following matters will be evaluated: .

1) Transient analysis assiing charging pump operation with wear to the Technical Specification limit for discharge pressure,

2) Operator action to reduce system pressure by PORV operation in order to assure minimum pump flow, i

l 8010 210 '20 Y

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SLNRC 80- 45 Page Two

3) Use of safety injection pumps in combination with the PORVs to provide backup capability in case of centrifugal charging pump degradation,

4) Loss of one centrifugal charging pump foi.owing a system re-pressurization transient,

5) Capability of the pumps with short term operation below the continuous duty minimum flow rate, and

6) Transient analysis assuming operation of the positive displace-ment charging pump.

Since any necessary design changes and evaluations o' i.5e above matters will be completed prior to operation of the SNUPPS plants, the interim procedural changes discussed in Reference 2 will not be implemented.

A final report on this matter will be provided for the SNUPPS plants when the necessary information is available. It is expected that this

, will occur in the first quarter of 1991. i Ver truly yours,

( -9.44 l

Nicholas A. Petrick l l

RLS:dck:la21 cc: Mr. James G. Keppler, Director, Region III, USNRC  !

Mr. Karl V. Seyfrit, Director, Region IV, USNRC Mr. Victor Stello, Jr., Office of I&E, USNRC, Washington, D.C.

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