ML20084E427
| ML20084E427 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 01/12/1970 |
| From: | Nelson E ROCHESTER GAS & ELECTRIC CORP. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084E428 | List: |
| References | |
| NUDOCS 8304150063 | |
| Download: ML20084E427 (3) | |
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ROCHESTER GAS AtID ELEC1RIC,CORPORAllON e 89 EAST AVENUE, ROCHESTER, ti.Y.1405' j
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c..g., 3 p-Dr. Peter A. Morris, Director
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Division of Iteactor Licensing bb ~ M, s g ' 7-United States Atomic Energy Commission L'
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Subject:
Failure of one safety injection train to operate on signal, Ginna Station Unit No. 'l Docket No.' 50-244
Dear Dr. Morris:
Cn January 3,1070, at 1022 hour0.0118 days <br />0.284 hours <br />0.00169 weeks <br />3.88871e-4 months <br />'s., a safety injection signal v/as properly initiated and the "B" train of this safeguards system failed to J,,f operate. At the time of the incident, the plant status was that the reactor gas.ccltical at less than one (1) per cent thermal power, and the secondary.
plant was dowH fbFplanned maintenance. Zero power tests'and flux f,
mappings were being performed on the reactor.
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The Instrument and Control personnel had requested peimission
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F to run calibration checks on the six main steam line pressure transmitters.
Id These transmitters are arranged equally in two channels and failure of any two transmitters in either one of the two channels will generate the safety,
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'f7 injection signal.
3 The Instrument and Control repairmen had received permission' to
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isolate and calibrate transmitter PT483. While calibrating th16 trans-
~ f mitter with a dead weight tester, the repairmen noted that transmitter..[ rj I
Pl'478 isolation valve bonnet was lealdng stetun. One of the Instrument '
A and Control repairmen closed the isolation valve PT478 and proceeded to t
3 notify the control room. However, as transmitter PT483 and transmitter y
PT478 are both in the "B" train, a safety injection signal had already been-
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initiated and the reactor tripped before any corrective action could be taken.
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- 3F On the signal only the "A" train associated equipment add valves n the safety injection ^ system operated. ' Since reactor conditions pre-y )),
cluded an accident, the pumps were stopped and the safeguards valves
,M reset to their normal operating position. Simulation of the condition which.
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. caused the initiation of the safety injection signal was duplicated and again
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' only the "A" train safety injection' system operated..
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' oarc January 12,16 V
2 m Dr. Ibter A. Morris Invectigation of the "E" train alac1cced failure of an W;-0 type relay contact to cloce properly and prevented the initiation tuid operation of the train of cafeguards equipment. Thic was evidenced when finger precettie applied to the relay contact leaves completed the circuit and the "B" c!Lfety injecticn train functioned.
The contactc on this relay were cleaned and when cafety injection cignal was initiated both traina operated.
However, with the cuecessful operation of the "B" train, three cafeguardo val'ces did not indi,cate r,aropor croration on the statuc b:nrd.
Thece valvec were:
(st) Air operated valve 053 (pressuricer liquid cpace icolation valve incide containment)
(b) Air operated valve 066C (Loop "B" hct leg sample line icglation valve outcide containment)
(c)
Meter operated valve 878B (2" cafety injecticn line to icop "B" cold leg incide centainment)
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The twc above air operated valves, 953 and 0600 were found to be < go4 (
operating properly, but their respective position indicator cwitchec were o
out of pacition and unable to make contact for proper position indication, y,
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Thece were adjusted.
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Motor operated valve MOV878B was found to have an open limit s
cwitch contact. This was also adjucted and the valve exerciced catic-factcrily seven concecutive times.
Thece equipment failures and adjustmento were reported by tele-phone on the day of cecurrence to Mr. Norman Mosely of the AEC Division of Compliance and thic was follcwed by a telegram to Mr. R. W. Kirkman, Director - Region I, Division of Compliance.
The safety injection "B" train was lact operated on Cetaber 22,1960, by cafety injection unblock cignal and the syctem performed correctly.'
Containment isolation valvec 953 and 966C were also operated cuccessfully cn this signal at that tirne.
MOV878 valve had been stroked by operation from the control board cwitch during the performance of cafeguard valve exercise on December 17, 1969. Atithat time automatic dicengagement of the manual operator did not occur and the valve failed to open. 'Ihe valve apparently k.
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ROCIIC5 T i'N C M Mm L t CC Tktr CORI'.
WCl I W onc.lanuary 12, 1970 3
ro Dr. Peter A. Morris hati been run down manually to a tightly closed positic,n and the Limitorque would 110t dicengage the manual operatoc Adjustmenta were made to the manual operator and the valve was r" sed succeasfully neveral times.
C'n the day of January 3,1970, and prior to the adjuctment of the limit cwitch cn MOVS78B the reactor was made critical to resume tecting.
l Within the next half hcur it was determined that returning the reactor to criticality wac in violation of the. Technical Specifications becauce the abow cafeguard was not operating properly. The reactcr was inunediately l
placed in hot chutdown at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, some fifty minutec after criticality.
l Thi:s waa reperted ac required. A FlanE Opsating Review Ccmmittee meeting,was called immediately to discuca the cituation. It was agreed that the reactor coulti te 1;eturned to cervice when the adjustments were satisfactorily completed.
Despite the reccgnized durability and overall reliability of the MG-0 type relay and the decigned action of this relay to wipe the contact curfaces upon operation there is the poasibility of random failure. It has been recommended by the Ginna Nuclear Safety Audit and Review Board that this particular relay be replaced and then examined thoroughly at our Company's laboratory and at the Wectinghouse laboratory. Design specifications for thic relay will be obtained for comparicon.
There are fourteen (14) additional LIG-6 auxiliary relaya in the safeguarde cystem. Each will be examined for cleanlineos and given continuity checka before return to power.
Very truly youra, kg&L
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hiward J. IIelcon l
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