ML20066A879

Final Deficiency Rept Re Centrifugal Charging Pump Operation After Secondary Side High Energy Line Rupture.Initially Reported on 800508.Studies Indicate Change in Charging Sys Necessary to Satisfy Requirements

ML20066A879
Person / Time
Site:	Wolf Creek, Callaway, 05000000
Issue date:	10/29/1982
From:	Petrick N STANDARDIZED NUCLEAR UNIT POWER PLANT SYSTEM
To:	Jay Collins, James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, SLNRC-82-42, NUDOCS 8211060261
Download: ML20066A879 (2)

Text

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4 SNUPPS Standardised Nuclear Unit Power Plant System 5 Choke Cherry Road Nicholas A. Petrick Rockville, Maryland 20050 Executive Director moil see.e010 October 29, 1982 SLNRC 82- 42 FILE: M-00BG SUBJ: Centrifugal Charging Pump Operation Follow-ing Secondary Side High Energy Line Rupture; 50.55(e) Report 80-02 Mr. James G. Keppler USNRC Office of Inspection and Enforcement 799 Roosevelt Road Glen Elyn, Illinois 60137 Mr. John T. Collins USNRC Office of Inspection and Enforcement 611 Ryan Plaza Drive Arlington, Texas 76102 Docket Nos.: STN 50-482 and 50-483

Reference:

1. SLNRC 80-28, Same Subject, dated 6/6/80

2. Westinghouse Letter (T. M. Anderson), NS-TMA-2245, to USNRC (V. Stello), dated May 3,1980, Same Subject

3. IE Bulletin No.80-18, dated 7/24/80

4. SLNRC 80-45, Same Subject, dated 9/15/80

5. SLNRC 81-22, Interim Reports on 10 CFR 50.55(e)

Matters, dated 4/1/81 Gentlemen:

On May 8,1980, SNUPPS informed the Nuclear Regulatory Commission, Region I Office of Inspection and Enforcement, of a potential deficiency in-volving centrifugal charging pump operation following a secondary side line rupture. Reference 1 reported this potential deficiency stating additional evaluation was required to determine if the potential problem was applicable to the SNUPPS plants. Reference 2 provided detailed information on the deficiency, described plant specific calculations that are required, and discussed possible corrective modifications. Sub-sequent to these submittals this same topic was addressed in Reference 3, but SNUPPS was not required to respond to the Bulletin. It was stated in -

Reference 4 that several potential design change alternatives were being evaluated and Reference 5 provided an interim report on this matter.

This letter provides the final SNUPPS response to this matter.

Extensive studies have been performed by Westinghouse and have shown that a change in the charging system design is necessary in order to satisfy the dual requirements of: (1) adequate minimum flow delivered by the centrifugal charging pumps to prevent pump damage and (2) adequate 8211060261 821029 PDR ADOCK 05000482 gy Ig S PDR ggy

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' Centrifugal Charging Pump Operation Following-ing Secondary Side High Energy Line Rupture Page 2.

mininum flow delivered to the reactor coolant system (RCS) for small-break LOCA's. The problem is that the miniflow recirculation valves (BG-HV 8110 & 8111) must be open when the charging pumps are not de--

livering flow to the RCS and must be closed when the pumps are providing flow to the RCS. Existing flow transmitters in the boron injection tank (BIT) injection lines (EM-FT 917A & 9178) are to be used to sense flow delivered to the RCS and to provide open or close signals to valves HV 8110 and 8111. Because the discharge lines of the two centrifugal charging pumps and the positive displacement charging pump are all interconnected, many combinations of centrifugal charging pump (CCP) flows and boron injection tank path flows are possible. This makes it extremely difficult to define setpoints for FT 917A & B to open and close HV 8110 and 8111 as needed to meet the functional requirements of the system.

The simplest solution to this problem is to operate the plants with either one of the manual valves (BG 8483A & C) in the CCP discharge lines closed. These valves are downstream of their respective BIT flowpath connections. This serves to decouple the discharge lines of the two CCP's and enables unambiguous setpoints for FT 917A & B to be defined.

SNUPPS will implement this solution. Therefore, the Significant Def-iciency Report No.80-2 regarding the centrifugal charging pumps is considered closed.

Very truly yours, Nicholas A. Petrick J0C/nid/1a26

. cc: G. L. Koester KGE D. T. McPhee KCPL D. F. Schnell UE i

J. H. Neisler NRC/ CAL i

T. E. Vandel NRC/WC