PNO-III-86-052B, on 860601,reactor Level Switches Failed to Actuate Properly.Testing of Operability of Switches Begun. Licensee Declared All ECCS Inoperable for Both Units

PNO-III-86-052B:on 860601,reactor Level Switches Failed to Actuate Properly.Testing of Operability of Switches Begun. Licensee Declared All ECCS Inoperable for Both Units

ML20211E461
Person / Time
Site:	LaSalle
Issue date:	06/09/1986
From:	Guldemond W, Wright G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-86-052B, PNO-III-86-52B, NUDOCS 8606160079
Download: ML20211E461 (1)

. DA Date June 9, 1986 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-III-86-52B AV This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region III staff on this date.

Facility: Commonwealth Edison Companuy Licensee Emergency Classification:

LaSalle Unit I and 2 Marseilles, IL 61341 Notification of an Unusual Event XX Alert Do.cket Nos: 50-373; 50-374 Site Area Emergency General Emergency Not Applicable

Subject:

REACTOR TRIP PROBLEM-STATUS REPORT FROM NRC AUGMENTED INVESTIGATION TEAM (SECONDUPDATE)

The Augmented Investigation Team (AIT) is continuing its review of the June 1, 1986, incident in which reactor level switches failed to actuate properly.

toch unit at LaSalle has approximately 65 Static-0-Ring switches in a variety of safety-related applications. The licensee has begun testing the operability of the switches in these applications.

Testing of the switches in two of three of the Residual Heat Removal Systems and the Higii Pressure Core Spray System showed that the switches did not actuate at the calibrated flow levels. However, in one of the Residual Heat Removal Systems, the switch actuated within the Technical Specification allowable value. The switches in these systems function to control the minimum flow valves, which open to permit a minimum flow through the system pumps.

The minimum flow provides cooling to the pumps.

The Static-0-Ring switch in the HPCS system, calibrated to actuate at a flow rate of 1,300 gallons per minute (gpm), actuated in the test at 530 gpm. Two switches in the RHR system, calibrated to actuate at 1,000 gpm, actuated in tests at flow rates rancing from 480 to 800 gpm.

As a result of these tests, the licensee has declared all Emergency Core Cooling Systems inoperable for both units.

! The AIT is monitoring the licensee's testing activities. The State of Illinois will be informed of this updated information.

! Region III (Chic ) was 1 rmed of th s update information by the AIT M 1 p.m., June 9, 1986.

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l This infonn curr t so t - m.

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CONTACT: . t . emond FTS 388-569 FTS 388-5574 i DISTRIBUTION:

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ACRS

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PDR RIII ResidenA,0f[o Licensee: 7. / (Corp. Of ice - Reactor Lic. Only) g61 79 860609 0 l PNO-III-86-452 PDR e o ber 1985 3h M