ML19247B798
| ML19247B798 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/31/1979 |
| From: | Crews J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML19247B793 | List: |
| References | |
| NUDOCS 7908130513 | |
| Download: ML19247B798 (2) | |
Text
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'hA L.wT C A E EX. CA U FO R ?a A H.%i .E WY ;! Si- @g MEMORANCUM FOR: M. C. Moseley, Director, Division of Reactor Operations g Inspection, IE:HQ mg? FRCH: J. L. Crews, Chief, RCNS Branch, Region V My SUSJECT: RANCHO SECO TURBINE AHD FEECWATER REACTOR TRIP M00IFICATIONS The purpose of this memorandunt is to highlight the design of the hard-wired e3 centrol-grade reactor trips that have been installed at Rancho Seco to actuate A on loss of main feedwater and turbine trip. m e W In a letter to Harold Denton dated May 14, 1979, SMUD described the design of T the above identified trips. Attached to the letter was a simplified drawing of a the trip circuit which is being subctitted as Enclosure A. As shcan in this (('g~ drawing, the two fee 6ater pressure switches PSL 31757 and PSL 317CS are in serii g which requires the loss of both feedwater pumps to initiate a reactor trip. Eg The circuit is designed such that the pressure switch contacts cust close to F;P energize the reactor trip relay (RXT). W 8t;; @3 Even though it is understead the trip circuits are to be installed as control r Er grade circuits, Region V is concerned that the non-fail safe design (need-to-h energize) may be less reliable than intended by the Ccamission's Order. -d! The Princical Inspector at Rancho Seco (Mr. Al Johnsen) has expressed sericus sc,, reservattens regarding the non-fail safe design. He reccarends that the license: MS be required to modify the circuit to make it fail safe. On May 18, 1979, Regian V con: acted Mr. Dale Thatcher (Electrical Engineer on MR Rd EM Revfew Task Force) and inforced nim of cur concern regarding the design of the above described Rancho Seco trip circuit. ,Q This matter was also discussed by telephone (J. L. Crews to E. L. Jorcan) wi:n I on May 16, 1979. _2... %s .-- ?.. g ; ;....._. Ycuc offfce cay wish ~ro Jdiscuss this,cencern with the Office of MRR'-for early -- ~ r --I:._.:resaluticn:&.. :: _QW.~~~--.sc_ '?.S1%-W _) - Wf:. * -~~ ~ ~ ~- ._..,:.-=v-_._.--.-~.-_ - ; - -;. -- : - . }- n, ~.= w w . :~2 ;._ = k ~h h [ b.$ q.- ~ t m
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