ML19317H017
| ML19317H017 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 10/28/1976 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| TAC-6710, NUDOCS 8004020694 | |
| Download: ML19317H017 (3) | |
Text
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1 L CeccM 195 u.s. NUCLE AO CE".ULATCGV *OMMISSiON DOC KET NUM BE R t> mi
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50-312
. NRC DISTRIBUTION Fca PART 50 DOCKET MATERIAL "
FROM:
DATE OF DOCUMLNT TO:
Sacramento Municipal Utility Dist..
10/28/76 Mr. Robert ti. Reid,
Sacramento, California oAve RECEivEo J. J. Mattimoe 11/3/76 jg.ETTE R ONoTORIZE0 PROP INPUT FORM NUMBER OF COPlES RECEIVED oRiciN AL
$UNCLASSIFIE D One signed COPY DESC RIPTION ENCLOSURE Ltr. re their 10/14/76 ltr. and our 8/11/76 ltr....concerning reactor vessel cvarpressurization events.
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REACTOR VESSEL OVERPRESSURIZATION ACKNOWLEDGED.
DISTRIBUTION PER C. BECH 10-21-76 DO NOT REMOVE Rancho Seco SAFETY FOR ATION/INFORMATION 11/4/76 RJL M ERANCH CIIIEF:
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g.sbus SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 s Street, Box 15830, Sacramento, california 95813; (916) 452-3211 October 28, 1976
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- Director of Nuclear Reactor Regulation
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h Attention: Mr. Robert W. Reid, Chief
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. Operating Reactors, Branch 4 g L(,
U. S. Nuclear Regulatory Comission n
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Washington, D. C.
20555 gf3 1976>.
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.b Rancho Seco Nuclear Generat
/f Station, Unit No. 1
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Dear Mr. Reid:
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On October 14, 1976 the Sacramento Municipal Utility District submitted an analysis of reactor vessel overpressurization events as requested in your letter of August 11,1976. As a result of this analysis, the District decided to add a dual setpoint feature to the pressurizer pilot actuated relief valve.
It is the intent of this letter to clarify the fact. that any maintenance performed on this valve would be performed during periods of reactor shutdown. At this time, a blank flange could be installed on the line where the relief valve is normally installed and automatic pressure relief would not be available through this valve.
It is reasonable to expect that during pers t when thic valve is out of service, operator action can be reliea upon to terminate any event leading to an overpressurization condition. The primary system would l
be in a cold condition when maintenance is being performed on this valve.
When the system is cold, events which could lead to overpres-j surization are precluded as described in our October 14, 1976 submittal with the exception of heatup above 200 F during which the high pressure injection system must be operable.
Additionally, in our letter of October 14, 1976, we comitted to changing operating procedures for Rancho Seco Unit 1 requiring opening the circuit breakers for the motor operators of the four high pressure injection valves during plant cooldown.
Since an auxiliary spray line from one of these high pressure injection lines is used at Rancho Seco during periods of cooldown, the District now finds it desirable to manually close and tag the stop check valve downstream of the isolation valva jn this line for this protection.
This will allow continued use of thd auxiliar spray line to the pressurizer during periods of system cooldc wn,
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- Mr. Robert W. Reid October 28, 1976 On the other hand, makeup water for level control is introduceo upstream of the stop check valve in another line.
Therefore, in this second line it is desirable to close the motor operated valve and open its breaker. Also, maintenance considerations make it desirable to have the option of closing the motor operated isolation valve or the manual stop check valve.
We intend to close one of the two valves in each line except for periods of high pressure injection system tests or when the system is required to be in service above 200 F.
The Sacramento Municipal Utility District feels that the analysis submitted on October 14, 1976 shows adequate protection of the primary system with the incorporation of these two modifications.
It is reasonable to expect that these modifications can be made by December 1,1976 and that an interim solution is not required.
Please note that the plant is now in operation.
It is never in a water solid condition even during shutdowns except for a primary system hydrotest. This greatly extends the time for operator action as described in our October 14, 1976 submittal.
Sincerely yours,
&&A u."
J.
Mattimoe Assistant General Manager and Chief Engineer l
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