05000298/LER-1980-050, Forwards LER 80-050/03L-0

Forwards LER 80-050/03L-0

ML19341A723
Person / Time
Site:	Cooper
Issue date:	01/14/1981
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19341A724	List: 05000298/LER-1980-050, Forwards LER 80-050/03L-0 05000298/LER-1980-050-03, /03L-0:on 801216,during Surveillance Testing of RHR Motor Operated valves,RHR-MO-25B,loop B Injection Line Inboard Isolation Would Not Open.Caused by Installation Error.Close Torque Switch Was Readjusted
References
CNSS800763, NUDOCS 8101270775
Download: ML19341A723 (2)

LER-1980-050, Forwards LER 80-050/03L-0

Event date:
Report date:
2981980050R00 - NRC Website

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CNSS800763 January' 14, 1981

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Mr. K. V. Seyfrit, Director

'N U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV.

611 Ryan Pla::a Drive Suite 1000 Arlington,' Texas 76011

Dear Sir:

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This report is submitted in accordance with Section 6. 7.2. 3.2 of the Technical Specifications for Cooper Nuclear Station and discusses. a reportable occurrence that was discovered on December 16, 1980.

In accordance with the requirements of IE Bulletin 80-17, Mr. Sp ngler was notified while he was on site December 16, 1980. A licensee event report form is also enclosed.

Report No.:

50-298-80-50 Report Date:

January 14, 1981 Occurrence Date: December 16, 1980 Facility:

Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

Conditions which led to operation in a degraded mode permitted by a limiting condition for operation as delinected in Section 3.5.A of the Technical Specifications.

Conditions Prior to Occurrence:

Steady state power operation at approximately 98% reactor power.

Description of Occurrence:

During surveillance testing of RHR motor operated valves, RHR-MO-25B, the "B" loop injection line inboard isolation valve would not open.

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Designation of Apparent Cause of Occurrence:

'RHR-MO-25B is-an Anchor 900#,'24", gate valve with a Limitorque SMB-3 operator. The apparent cause of-the avent is related to the closing torque switch setting. The closing torque switch was set at "3.0" which is close to the manufacturer's maximum limit of "3.5".

- This was the original setpoint of the torque switch. The identical valve in the "A" loop was set during installation at "1.0" but was later changed to "2.0" to meet local leak rate re-quirements. Apparently the valve during previous operation was close to sticking and certain circumstances during this event prevented it from opening. An evaluation is being performed to i

determine _the possibility of a hydraulic lock occurring in the valve body.

If.there is evidence of this, an updated report will be submitted.

Analysis of.0ccurrence:

RHR-MO-253 is the loop "B" RHR inj ection line inboard isolation valve. This valve is a normally closed valve that receives an open signal for LPCI initiation.

In the event of LPCI initiation, this valve would not have opened remotely. The redundant loop was operable and uould have operated satisfactorily had it been neces-sary. In addition, both diesel generators were operable. This occurrence presented no adverse consequences from the standpoint of public health and safety.

Corrective Action

The valve was opened manually. The close torque switch for the subject valve was set at "2.0" to correspond to the setting of RHR-MO-25A.

This will prevent the valve from closing too hard. An evaluation is ongoing to determine the possibility of a hydraulic lock occurring in the valve body. An updated report will be sub-mitted if this evaluation indicates this was a contributing factor.

Unrelated to this event, it was noted during our investigation that the open torque switch was not jumpered out on both RHR-MO-25A & B as indicated on the valve wiring diagram. The intention of jumper-ing out the open torque switch is to override the open torque switch and thus in the event of an emergency, eliminate the chances of the valve torquing out in the open direction. This discrepancy a.

was corrected. It should be noted that both open torque switches 4

were set at the highest value which effectively accomplished the same result. This statement is justified in that an overload was received on the motor when the RHR-MO-25B stuck in the seat.

Sincerely, L. C. Lessor Station SuperLitendent Cooper Nuclear Station LCL:cg Attach.