ML20067B181
| ML20067B181 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/08/1982 |
| From: | Crane P PACIFIC GAS & ELECTRIC CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8212060078 | |
| Download: ML20067B181 (2) | |
Text
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assevaar soiteat couantt November 8, 1982 Mr. R. H. Engelken, Regional Administrator U.S. Nuclear Regulatory Commission, Region V 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596-5368 Re: Docket No. 50-323 Diablo Canyon Unit 2 10 CFR 50.55(e) Report -
Water Hammer Phenomenon in ASW System
Dear Mr. Engelken:
On October 8, 1982, Mr. D. F. Kirsch of yo"r office was notified by telephone of a water hammer phenomenon in the Auxiliary Saltwater ( ASW) System of Diablo Canyon Unit 1.
Mr. J. D. Shiffer's letter of the same date to Mr. R. H. Engelken confirmed our telephone notification and was submitted pursuant to Technical Specification 6.9.1.12.1 for Unit 1 and 10 CFR 50.55(e) for Unit 2.
This submittal represents the final report on the subject for Unit 2.
The ASW System design is essentially identical for both Units 1 and 2; therefore the same water hammer phenomenon is expected in Unit 2.
Testing performed on the ASW system for Unit I has shown that the system is susceptible to water hammer effects during anticipated operational transients.
These transients include pump trip and restart sequences such as would occur f ollowing a loss of of fsite power. While the peak pressure observed during this testing exceeded the system design pressure of 100 psig specified in the FSAR, no system failure or degradation was observed which would have
, prevented the system from performing its intended safety function.
Ie Is 0212060078 821108 PDR ADOCK 05000323 hA"&
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Mr. R. H. Engelken Novembzr 8, 1982 Page 2.
A test to definitely establish the cause of the water hammer was perfo rmed. An isolatable vacuum breaker was added to the ASW system as a method of eliminating the water hammer effect in the system. The results of the test indicated that 1) without the vacuum breaker installed, water column separation-recombination caused a detectable water hammer, and
- 2) with the vacuum breaker installed, no water hammer or excessive pressure transients were observed.
A determination was made that installation of the vacuum breaker would eliminate the water hammer effect from the ASW System. The addition of the vacuum breaker will not degrade the safety function of the system.
j A design change is being prepared to install the vacuum breaker on the ASW system piping. This is expected to be implemented prior to Unit 2 fuel
- loading, i
Very truly yours, Philip A. Cranc, Jr.
cc:
Mr. George W. Knighton, Chief Licensing Branch No. 3 Division of Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Service List l
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