ML19318A059

Deficiency Rept Re Substantial Safety Hazard in Westinghouse Centrifugal Charging Pump Operation.Interim Mods Suggested

ML19318A059
Person / Time
Site:	Summer
Issue date:	06/13/1980
From:	Crews E SOUTH CAROLINA ELECTRIC & GAS CO.
To:
Shared Package
ML19318A060	List: ML19318A059 ML19318A062
References
NUDOCS 8006180401
Download: ML19318A059 (5)

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SOUTH CAROLINA ELECTRIC & GAS COMPANY aost omes som re.

COLUM81A,$0UTH CAROLINA 29218 E.H. Catws. J n.

Mct-Pessissue ame Gaove Esscuerve

("'"**"**"C*"'""c'*" June 13, 1980 Mr. James P. O'Reilly U. S. Nuclear Regulatory Commission Region II Suite 3100 ~

101 Marietta Street, N. W.

Atlanta, GA 30303

Subject:

Virgil C. Summer Nuclear Station, Unit 1 Reportable Substantial Safety Hazard Centrifugal Charging Pump Operation Following Secondary Side High Energy Line Rupture Docket No. 50/395 i

Dear Mr. O'Reilly:

l On May 8, 1980, Westinghouse Electric Corporation notified South  !

Carolina Electric & Gas' Company orally of a reportable substantial safety hazard. On the same day, Mr. Tom Burdette of NRC Region II was i informed of the information received from We stinghouse.

By letter dated May 16, 1980, Westinghouse confirmed the telephone conversation and supplied a copy of the letter to Mr. V. Stello, Office of Inspection and Enforcement.

A review of the Westinghouse Safety Injection (SI) Termination Criteria following a secondary high energy line rupture (feedline or steamline rupture at high initial power levels) has revealed a potential for consequential damage of one or more centrifugal charging pumps (CCP's) before the SI termination criteria are satisfied and CCP operation terminated, causing a substantial safety hazard defined by 10CFR21. I Under South Carolina Electric & Gas Company's program, we are reporting I this as a significant deficiency under 10CFR50.55(e). Detailed information is presented in Attachments I and II.

Westinghouse has provided interim modifications and has initiated i efforts to perform plant specific analyses for nonoperating plants and I to develop design mcdifications to resolve y identified concerns. l When the analysis is performed and the modi ica ons are identified, we l will inform you of the final decision.

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Ver truly yours, ,

c/

E. H. Crews, Jr.

$ ;j AGA:rm Enclosureg006180 q'g

Mr.' James P. O'Reilly Page 2 June 13, 1980 CC: U. S. Nuclear Regulatory Commission-Document Management Branch Washington, DC. 20555 H. T. Babb -

E. H. Crews, Jr.

O. S. Bradham D. A. Nauman H. Radin J. Skolds V. C. Summer NPCF/Dixon File O

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ATTACHMENT I 10CFR21 - SUBSTANTIAL SAFETY HAZARD

1. Name and Address of Reporting Individual.

A. G. Alvarez South Carolina Electric & Gas Company P. O. Box 764 Columbia, SC- 29218

2. Identification of Basic Component. '

Centrifugal Charging Pump Operation Westinghouse Electric Corporation

3. Identification of Firm Supplying Component.

Westinghouse Electric Corporation PWR Systems Division Pittsburgh, PA 15230

4. Nature of Defect, Substantial Safety Hazard Created and Evaluation A review of the Westinghouse Safety Injection (SI) Termination Criteria following a secondary side high energy line rupture 1 (feedline or steamline rupture at high initial power levels) has '

revealed a potential for consequential damage of one or more centrifugal charging pumps (CCPs) before the SI termination criteria are satisfied and CCF operation terminated. Such consequential damage may adversely impact long-term recovery operations for the initiating event and is not permitted by design criteria. This concern exists for plants which utilize the CCPs as Emergency Core Cooling System (ECCS) pumps, where the CCPs are automatically started, and where the CCP miniflow isolation valves are automatically isolated upon safety injection initiation.

Following a secondary side high energy line rupture and associated reactor trip, Reactor Coolant System (RCS) pressure and temperature initially decrease. Safety injection is actuated and the CCPs start to increase RCS inventory. Reactor Coolant System pressure and temperature subsequently increase due to the loss of secondary inventory, steamline and feedline isolation, RCS inventory addition and reactor core decay heat generation. The accident scenario

.may vary with rupture size and specific plant design, but it will develop into a RCS heatup transient with accompanying increase in

'RCS pressure. As RCS pressure increases, the pressurizar power-operated relief valves (PORVs) are designed to limit RCS pressure to 2350 psia.

Although these valves are normally available, they are not designed as safety-related equipment. It can be postulated that, due to either loss of offsite power,-adverse environment inside containment,

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.the pressurizer PORV in manual mode, or the PORV block valve in a closed position, due to PORV leakage, the pressurizer PORVs may not be operable. As a result of the RCS heatup and inventory increase, the RCS pressure could rise to the pressurizer safety valve setpoint of 2500 psia within approximately 200 seconds and remain at that pressure until transient " turnaround". Transient

" turnaround" can occur between 1800 and 4200 seconds depending i on operator action and available equipment. During the initial portion i of this transient, the SI termination criteria may not be satisfied. '

Consequently, the RCS pressure can reach the pressurizer safety valve relief pressure before CCP operation is terminated. During this period, the minimum flow required for CCP operation must be ,

satisfied by flow to the RCS since the CCP miniflow isolation valves  !

are automatically closed on safety injection initiation. This requires that the CCPs be able to deliver their minimum required flow to the RCS at the safety valve setpoint pressure.

To evaluate this concern, Westinghouse has developed a calculated method, generic to all plants. Based on this generic evaluation, there is reason of concern. (Refer to Attachment II).

5. Date Information of Defect was Obtained.

Westinghouse Electric Corporation's telecon of May 8,1980 Westinghouse Electric Corporation's letter of May 16, 1980

6. Number and Location of Defect There are three (3) centrifugal charging / safety injection pumps affected by the Westinghouse Safety Injection (SI) Termination Criteria at the V. C. Summer Nuclear Station.

7. Corrective Action ,

l Westinghouse Electric Corporation has suggested interim modifications and for non-operating plants they have initiated efforts to perform additional plant specific analyses and to develop design modifications to resolve any identified concerns. Refer to Attachment II.

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- PinsburghPenr#vania15230 May 16, 1980 Mr. 0. W. Dixon, Manager -

Production Engineering S.O. CGE-1000 South Carolina Electric c. Gas Company .

g l P. O. Box 764 i Columbia SC'29218 .

Dear Mr. Dixon:

SOUTH CAROLINA ELECTRIC & GAS COMPANY VIRGIL C. SUMMER NUCLEAR STATION I Centrifugal Charging Pump Operation Following Secondary Side High Energy Line Rupture -

Potential Significant Deficiency This letter confirms a telephone conversation with R. B. Clary and A. G. Alvarez of SCE&G on May 8,1980. During this conversation Westinghouse notified SCE&G of the subject deficiency. Further, we noted that further information would be ,

forthcoming in the near future. l 1

in accord with the commitment made during the May 8, 1980 telephone conversation, attached is Westinghouse letter NS-TMA-2245 to the NRC. This letter contains additional background information on the subject potential significant deficieracy as well as recommendations and two possible Interim modifications to address the basic concern until necessary design modifications can be implemented. Further, a list of af fected plants is attached to the Westinghouse letter.

Should you have any further qt estions or comments, pl.e:sc cdvisc.

Very truly yours, WESTINGHOUSE ELECTRIC CORPORATION l l

R. A. Stough, Project Engineer SCESG Project RAS:gcc -

Attachment -

cc: 9. W..Dixon IL 1A H. T. 9:bb It'IA E. Wielkopolski 4L 4A l T. C. Nichols,'Jr. IL l

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E. H. Crews IL _:

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'R. C. Holzwarth IL lA D. A. Nauman'll H. Radin IL-O. S. Bradham Il

! Plant Numerical Records System IL 1A l Nuclear Project Central File il IA

( W. A. Williams, Jr. IL 1A

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