ML19317G936
| ML19317G936 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 12/15/1977 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004020593 | |
| Download: ML19317G936 (3) | |
Text
o DISTRIBUTION AFIEE ISSUANCE OF OPE 10"'T.NG LICENSE U.S.NUCLEA9 f.E!UI.ATORY COMMISSI MCKET NUM SED 30 -3/a2 RC PopM If ss w C DISTRIBUTION PoM PART 50 DOCKET MATERIAL 0^T80'""*"'"Y FROR SMUD 0-Mr. Robert W. Reid 12/1s/77 Sacramento, Ca.
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,,$}{ft[ct.ASSIPf E D i JI 6 A16O Ocopy ENCLOSU RE cascniPTioN purnishing response to NRC's Itr dtd 09/14/77... Consists of analysis of the potential for, and consequences of, boron dilution accidents at Rancho Seco, Unit 1.
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, Box 15830. Sacramento, California 95813; (916) 452-3211 December 15, 1977 Director of Nuclear Reactor Regulation Attention:
Mr. Robert W.
Reid, Chief Operating Reactors, Branch 4
.; 3 wj U.
S. Nuclear Regulatory Commission b e..e -
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Rancho Seco Nuclear Generating Station, Unit No. 1
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Dear Mr. Reid:
Your letter of September 14, 1977 requested the Sacramento Municipal Utility District to provide an analy-sin of the potential for, and consequences of, boron dilu-tion accidents at Rancho Seco Nuclear Generating Station, Unit No. 1.
In this letter you referred to an incident at an operating PWR facility where there was an inadver-tent injection of a portion of the contents of the NaOH tank into the reactor coolant systen while surveillance testing was being performed on the NaOH tank isolation valve.
The design of the spray additive system at Rancho Seco Unit No. 1 is substantially different from that at the above facility.
At the above plant,.NaOH is added to the reactor building spray and decay heat removal systems by gravity draining through one motor operated safety features valve into either of the two legs in each system.
The Rancho Seco Unit No. 1 design incorporates spray additive eductors which force the NaOH into only the reactor building spray system.
This does not provide a path for the injection of NaOH into the reactor coolant system.
There is a provision for adding NaOH to the decay heat system for pH control following a loss of coolant accident.
This is through two 2-inch lines, one from each leg of the reactor building spray system to the corresponding leg of the decay heat system, and each line contains two manually operated valves.
This provision would not be utilized until well after a LOCA.
A single failure of one of these two valves would not permit the injection of NaOH into the reactor coolant system.
AN ELECTRIC SYSTEM S E RVIN G MORE THAN 600,000 IN THE HEART OF C A LI F0 R N I A
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a Mr. Robert W. Reid December 15, 1977 The Sacramento Municipal Utility District has therefore concluded that a moderator dilution accident is not-possible at Rancho Seco Unit No.
1.
The District considers the moderator dilution accident analysis pra-sented in the Rancho Seco FSAR, Section 14.1.2.4 to be'still cpplicable.
Sincerely.yours, kN ohn
. Mattimoe Assistant General Manager and Chief Engineer i
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