ML19319D983
| ML19319D983 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 01/06/1977 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML19319D984 | List: |
| References | |
| NUDOCS 8003270694 | |
| Download: ML19319D983 (2) | |
Text
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t eM SACRAMENTO MUNICIPAL UTILITY DISTRICT C 1708 59th Street. Box 15830, Sacramento, California 95813;(916)452 3211 January 6, 1977 4
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N Mr.
R. !!. Engelken Director of Regulatory Operations gy NRC Operations Of fice, Region V
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1990 N. California Boulevard Walnut Creek Plaza, Suite 202
%j Walnut Creek, California 94596
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Re: Operating License DPR-54 III Docket No. 50-312 Reportable Occurrence 76-18
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Dear Mr. Engelken:
In accordance with Technical Specifications for Rancho Seco
.J Nuclear Generating Station, Section 6.9.1, and Regulatory Guide 1.16, Revision 4, Section C.2.a(5), the Sacramento Municipal Utility District
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hereby submits a written follow-up report on Reportable Occurrence 76-18, initially submitted to NRC on December 28, 1976.
As stated in the initial report, Babcock and Wilcox has informed the District that studies indicate the possibility that Westinghouse Model 59Pl! pressure transmitters will fail when subjected to a post-
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LOCA environment.
It is postulated that these failures would result in high pressure readings from these transmitters.
In the Rancho Seco plant, one of these transmitters (PT 21099) is in use as an interlock signal for the second isolation valve on the Decay lleat Removal System.
If this transmitter were to fail with a reading higher than 255 poig, the interlock would not permit the isolation valve to open.
As described in our letter to Mr. Reid of NRC, Washington, on
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March 11, 1976, this valve must be opened within seven days following a LOCA to allow recirculation flow through the core for the prevention of boron precipitation. To prevent loss of the recirculation due to E
the valve interlock, Emergency Procedure D.5, " Loss of Reactor Coolant /
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Reactor Coolant System Pressure", has been temporarily revised. The revision details a method to bypass the interlock if in fact the transmitter does fail following a LOCA. This method has been verified by a special l
test, STP-604, " Decay lleat Valve (llV-20002) Interlock Override Test", the n
l results of which were reviewed and approved by the Plant Review Committee.
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THIS DOCUMENT CONTAINS POOR QUALITY PAGES 7g,
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l Mr. R. H. Engelken. January 6, 1977 The NSSS vendor, Babcock and Wilcox, has committed to provide the 6
District with a permanent solution in the form of a Field Change Notice.
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The changes required by this Notice will be implemented by March 31, 1977.
There was no plant transient associated with this event.
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l Respectfully submitted, V ".
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l J. J. Mattimoc j'
Assistant General Manager l
and Chief Engineer 1
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l cs: Director, MIPC (3) l.
Director, IE (30) i I
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