ML19305C085
| ML19305C085 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/05/1980 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0578, RTR-NUREG-578 NUDOCS 8003250573 | |
| Download: ML19305C085 (2) | |
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$ SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 SMUD 95813; (916) 452 3211 March 5, 1980 Director of Nuclear Reactor Regulation Attention: Mr. Robert W. Reid, Chief Operating Reactors, Branch 4 U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Docket No. 50-312 Rancho Seco Nuclear Generating Station, Unit No.1
Dear Mr. Reid:
Section 2.1.3.b of NUREG-0578 required that the District consider additional instrumentation necessary for monitoring inadequate core cooling.
The District's letters of October 18, 1979 and November 26, 1979 committed the District to such a review. Specifically, they committed the District to consider reactor vessel level indication as a possible indicator of inadequate core cooling.
In con, junction with inadequate core cooling guideline development, the District considered reactor vessel level indication. We conclude that reactor vessel level indication is not an easily used, unambiguous indication of the inadequate core cooling. Reactor vessel level indication must be temperature compensated.
It must be compensated for delta P's induced by both nbtural circulation and reactor coolant pump flow.
The District also considered the possibility cf using hot leg level indication. Hot leg level indication would introduce most of the same ambiguities associated with reactor vessel level indication.
The results of this effort lead the District to conclude that neither reactor vessel level indication nor hot leg level indication satisfy the NRC desire for " unambiguous, easy to interpret indications of inadequate core cooling *.
Inclusion of these difficult to interpret level indications drives the operator toward sensory saturation.
Inadequate core cooling is satisfactorily indicated by existing l
instrumentation which gives more directly usable infomation. Specifically,
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8003250573
s Mr. Robert W. Reid March 5, 1980 reactor coolant system pressures and temperatures provide information related
'to reactor coolant system status. Reactor coolant system pressure and temperature are now synthesized to directly provide reactor coolant system saturation information.
In addition, incore monitor assembly thermocouples provide temperature information at the top of the core.
These existing instrument indications provide multiple capabilities to detect, analyze and eliminate inadequate core cooling situations.
Sincerely, ohn Mattimoe Assistant General Manager and Chief Engineer l
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