ML20212F538

Safety Evaluation of Water Hammer Events & Corrective Actions Taken to Ensure Nuclear Svc Water Cooling Water Sys Integrity & long-term Operability.Sys Functional Integrity & long-term Operability Capability Adequate

ML20212F538
Person / Time
Site:	Vogtle
Issue date:	01/08/1987
From:	NRC
To:
Shared Package
ML20212F524	List: ML20212F520 ML20212F538
References
NUDOCS 8701120047
Download: ML20212F538 (2)

Text

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b ENCLOSURE SAFETY FVALUATION GN THE V0GTLE NSCW WATERHAMMFR EVENTS The staff has reviewed the applicant's report, " Loss of Offsite Power Transient Test of the Nuclear Service Cooling Water System," (NRC Accession No. 8612790179) and met with the applicant on December 15,19P6, to discuss waterharner events in the nuclear service cooling (NSCW) system.

In a letter dated December 23, 1986, frcm J. A. Bailey to B. J. Youngblood, the applicant provided further discussion of the woterhammer events and the corrective actions taken to ensure the systen integrity and long-tem operability in response te cucstionb raised at the meeting.

During recent testing on train A of the hSCW system, two unanticipated waterhammer events were experienced. The tests were conducted to determine the hydraulic behovior of the NSCW system during a loss-of-offsite power (LOOP) pump restart.

Except for the two waterhamer events described belew, the test confirmed that the NSCW system in the final tuned configuration will not result in significant waterhammer loads during LOOP or normal restart ccnditions.

For the two waterhamer events experienced, one event was causec by a missing temporary jumper in an electrical circuit which prevented a tower valve from opening. The second more severe event was caused by a premature manual punip start with two valves not in their required pump start position. The peak pressure during the second (more sevt.e) event was estimated to be a maximcr cf 900 psig at certain locations in the systent and in the range of 400-600 psig et other locations.

The applicent developed corrective actions to detemine the effects of the waterhammer on system integrity and Icng-term operational capability. The prcgram consisted of (1) piping and pipe support walkdowns to identify damage, (2) a system operability check for affected valves, (3) inspecMon of heat exchangers for leakages, (A) snubber operability tests, and (t; piping stress

' analyses to evaluate local and general membrane stresses in the system. In addition, affected a review was components (e.g., conducted pumps, heat to evaluate valves exchangers, the acequacy of potentially ) and and irstrerents the overall effect of the transient on the system.

The results of the above-described walkdowns, inspections, tests, and analyses, identified re darrage to components which could be directly attributed to the waterhamer events. However, in the inspection process, one snubber was iden-tified which failed its operability (stroke) test. The failed snubber was part of a tandem peir in which the other (parallel) snubber was tested and found fully operational. Thus, it could not be established conclusively whether the damage to the failed snubber was caused by the waterhammer event. The two snubbers have since been upgraded to a larger capacity (as part of a previously planned design change for increased seismic anchor motions).

Based on its review of the applicant's submittal, the staff concludes that the NSCW system adequate. functional isintegrity This conclusion based onend (1 Icng-) term operational the results capability are of the applicant's walkdowns, inspections, tests, and analyses verifying the adequacy of the NSCW system functional integrity and (2) the results of the final tuned configuration tests demonstrating that future waterhammer events are not likely to cause significant loads in the otoing system during LOOP or pump restart.

8701120047 870108 PDR ADOCK 05000424 A PDR

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g Mr. J. P. O'Reilly Georgia Power Company Vogtle Electric Gererating Plant cc:

Mr. L. T. Gucwa Restdent Inspector Chief Nuclear Engineer Nuclear Peculatory. Coi111ssion Georgia Power Company P. O. Box 57? ~-

P.O. Cox 4545 Vaynesboro, Georgia 30830 Atlanta, Georgia 30302 Fr. Ruble A. Thomas Deonish Kirkland, III, Counsel Vice President - Licensing Office of the Consumr s' Utility Vogtle Project Council Georgia Power Cemrany/ Suite 225 Southern Company Services, Inc. 32 Peachtree Street, N.W.

P.O. Box 2625 Atlanta, Georgia 30303 Binningham, Alabama 35202 James E. Joiner Pr. Donald 0. Foster Troutman, Sanders, Lcckeman,. '

Vice President & Project General l'.anager & Ashmore Georgia Power Company Candler Building ,

Post Office Box 299A, Route 2 127 Peachtree Street, N.E.

Waynesboro, Georgia 30830 Atlanta, Georgia 30303 Danny Feig Mr. J. A. Bailey 1130 Alta Avenue Project Licensing Manager Atlanta, Georgia 30307 Southern Company Services, Inc.

P.O. Box 2625 Carol Stangler Birmingham, Alabama 35202 Georgians Against Nuclear Errrgy 425 Euclid Terrece Ernest L. Blake, Jr. Atlanta, Georgia 30307 Bruce W. Churchill, Esq.

Shaw, Pittman, Potts and Trowbridae 2300 N Street, N.W.

' Washington, D. C. 20037 Mr. G. Bockhold, Jr.

Vogtle Plant Manager Georgia Power Cor.cany Route 2, Box 299-A Waynesboro, Georgia 30830 Regional Administrator, Region II U.S. Nuclear Regulatory Counission 101 Marietta Street, N.W., Suite 2900 Atlanta, Georgia 30323 Mr. R. E. Conway Senior Vice President and Project Director Georgia Power Company Rt. 2, P. O. Box 299A Waynesboro, Georgia 30830 l

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