ML18081A616
| ML18081A616 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 11/03/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18081A615 | List: |
| References | |
| NUDOCS 7911280224 | |
| Download: ML18081A616 (2) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY.THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING WATER HAMMER IN FEEOWATER. PIPING AT SALEM NUCLEAR GENERATING STATION, UNIT NO. 1 DOCKET NO. 50-272 INTRODUCTION Steam generator water hammer has occurred in certain nuclear power plants as a result of the rapid condensation of steam in a steam generator feedwater line and the consequent acceleration of a slug of water which upon impact within the piping system causes undue stresses in the piping and it~ support system.
The significance of these events varies from plant to plant. Since the total loss of feedwater could affect the ability of the plant to cool down ~fter a reactor shutdown, the NRC is concerned about these events occurring, even though an event with potentially serious consequences is unlikely to happen.
Because of the continuing occurrence of water hammer events, the NRC in September 1977, informed all PWR licensees that water haJ'IITler events due to the rapid condensation of-steam in the feedwater lines of steam generators represented a safety concern and that further actions by licensees for Westinghouse and Combustion Engineering designed nuclear steam supply systems are warranted to assure that an acceptablylow risk to public safety due to such events is maintainedo Accordingly, these licensees were requested to submit proposed hardware and/or procedural modifications, if any, which would be necessary to assure that the feedwater lines and feedrings remain
.filled with water during normal as well as transient operating conditions.
At the S?me time, the NRC provided each PWR licensee with a copy of its consultant 1 s report, "An Evaluation of PWR Steam Generator Water Hammer",
In its response, the licensee described the means employed at Salem-1 to reduce the potential for steam gener*ator water harrmer include loop seals, J-Tubes, automatic initiation of auxiliary feedwater flow and an administrative limit on the flow of auxiliary feedwater in the event that a feedwater line might contain steam.
EVALUATION Our consultant, EG&G Idaho Inc., prepared the attached evaluation of steam generator water hammer at Salem-1 *as part of our technical assistance program.
We have reviewed this report together with the licensees submittals dated June 27, 1975 and January 10, 1978.
- e CONCLUSION Based on our knowledge of water hammer phenomena, and our review of the licensee responses and the enclosed evaluation report, we concur with our consultants conclusion that the means for reducing the potential for steam generator water harrmer at this facility are adequate. These means are, therefore, acceptable to the staff and no further action is required of the licensee with regard to steam generator water hanuner.
REFERENCES
- 1. Letter from R. L *. Mittl to W. A. Giambusso, Subject - "Steam Generator Feed Line Water Hanvner 11, June 27, 1975.
- 2.
Letter from F. P. Librizzi to G. Lear, Subject - "Steam Generator Feedwater Water Hammer", January 10, 1978.