ML19274D181

Informs NRC of Corrective Actions Taken Re Potential Significant Deficiency in Design of Svc Water Reservoir Spray Cooling Capability.Final Rept Will Be Submitted by 790210 & Will Document Efforts to Ensure Design Capability

ML19274D181
Person / Time
Site:	North Anna
Issue date:	01/10/1979
From:	Brown S VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
720A, NUDOCS 7901150133
Download: ML19274D181 (2)

Text

.

• 4 VIRGINI A EL ECTRIC AND POWER COMP ANY, RICNMOND, VIRGINI A 23261 January 10, 1979 Mr. James P. O'Reilly, Director Office of Inspection & Enforcement Serial No. 720A PSE&C/JMD:bep/mc U. S. Nuclear Regulatory Comission Region 11 101 Marietta Street, Suite 3100 Docket No. 50-339 Atlanta, Georgia 30303

Dear Mr. O'Reilly:

Under the provisions of 10CFR50.55(e) NRC Region II was notified on December 11, 1978 of a potential significant deficiency in the design of the service water reservoir spray cooling capability. On December 8, 1978 our personnel discovered that breaks occurred in underwater portions of the Unit 2A and 28 spray header piping. Several sections within the Unit 2A and 2B arrays of the service water reservoir fiberglass spray system failed during a testing sequence. The Unit 2A array failure was confined to one detached riser saddle. The Unit 2B array failures were associated with the fiberglass piping and the bonded joints. One 18 inch fiberglass pipe sepa-rated following a circunferential material failure at a transition reducer.

Two 10 inch joints, downstream of the 18 inch failure, and 3 riser saddle joints on the 10 inch line, failed as a result of the axial movement of the 18 inch lina. The service water system had been operating at steady state, at a pressure lower than the system hydrostatic test pressure, at the time of failure. It has been determined, following a surface inspection of the impervious reservoir liner, that minor erosion resulted from the affluent at the pipe break.

A minor amount of erosion would not affect the functional integrity of impervious liner.the liner, and it will continue to perfom its function as an Corrective actions have been initiated to restore the system to full operating capacity. The riser opening on the 2A array has been plu spare nozzles opened on the array to obtain 216 operating nozzles. gged Theand2A array was successfully leak tested utilizing divers to visually inspect the system under operating conditions.

The undamaged portions of the 2B array are scheduled to undergo a struc-tural integrity test at the system hydrostatic test pressure. Divers will visually arsas. inspect the array during the integrity test for possible damaged An engineering evaluation is currently underway to detemine an appropriate method of rejoining the detached portions of piping. Following completion of the 2B array repair, the system will be subjected to the system hydrostatic test pressure to verify system integrity.

D 7 901 15 01 B

Mr. James P. O'Reilly 2 This 30 day report shall be considered an interim report. A final report will be subhitted by February 10, 1978, to document the measures to be taken to ensure the design capability of the 2B spray array.

Very truly vours, Y '

, , -- , i !

,/

Sin C. Brown, Jr.

Senior Vice President Power Station Engineering and Construction cc: Mr. John G. Davis, Acting Director Office of Inspection & Enforcement Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation

.