PNO-V-87-059, on 870831,five People Involved in Operating Cooling Suction Valve 2HV-9378 Found Contaminated by I-131 Due to Unisolable Leak in Valve.Caused by Failure of Valve & Valve Packing.Nature of Failure Under Investigation

PNO-V-87-059:on 870831,five People Involved in Operating Cooling Suction Valve 2HV-9378 Found Contaminated by I-131 Due to Unisolable Leak in Valve.Caused by Failure of Valve & Valve Packing.Nature of Failure Under Investigation

ML20238C323
Person / Time
Site:	San Onofre
Issue date:	09/01/1987
From:	Johnson P, Tatum J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-87-059, PNO-V-87-59, NUDOCS 8709100037
Download: ML20238C323 (2)

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.PREL1MINARY NOTIFICATION OF EVE R UNUSUAL OCCURRENCE--PNO-V-87-59 Date 09/01/87 u -This. preliminary notification constitutes EARLY notice of events of POSSIBLE safety or -

Epublic interest _ significance. The information presented is as initially received without verification or evaluation and is basically all that is known by Region V staff

on this date.

I FACILITY: . SOUTHERN CALIFORNIA EDISON Emergency Classification j SONGS UNIT 2 hutification of Unusual Event i DOCKET N0. 50-361 Alert SAN CLEMENTE, CA Site Area Emergency General Emergency X Not Applicable

SUBJECT:

UNIS0LABLE LEAK IN SHUTDOWN COOLING SYSTEM-At 6:45 p.m.- (PDT) on 8/31/87, with the reactor in Mode 5 on shutdown cooling and one reactor coolant' pump (RCP) in operation, maintenance personnel reported leakage from shutdown cooling suction valve 2HV-9378, which is not isolable from the reactor coolant system (RCS) (shutdown cooling was and is still in service through another valve in a . parallel line). Initial licensee estimates of the leak rate were 60 - 100 GPM at a RCS temperature of 125 degrees F and a RCS pressure of 350 psig, maintained with a pressurizer bubble. The leaking valve is located inside containment. The licensee maintained RCS inventory by using charging pumps for makeup, and pumped the leakage from the containment sump to a radwaste collecting tank.

The licensee. stopped the operating RCP at 7:25 p.m., began reducing RCS temperature, and initiated auxiliary spray to reduce RCS pressure and cool down the pressurizer. The containment equipment hatch, which was initially open, was closed at 8:17 p.m. Pressure'and temperature had been reduced to ibout 100 psig and 100 degrees F by about 9:00 p.m., with an estimated leakage rate of 30 - 35 GPM under these conditions. The pressurizer was taken

-solid at 9:40 p.m. An attempt by maintenance personnel to stop the leakage at about this time (by inserting packing) was unsuccessful. Pressurizer cooldown and RCS pressure reduction continued through the night. The RCS reached essentially atmospheric pressure at about 7:00 a.m. on September 1, with about 25 psig static head pressure at the valve. The estimated leak rate under these conditions was approximately 20 GPM. A containment entry was in progress as of about 9:30 a.m. to attempt to stop the leakage. As of 11:30 a.m. PDT, i the licensee reported that packing had been installed in the valve packing gland ano leakage had been' essentially stopped (reduced to a drip).

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An update on radiological considerations, provided by the licensee at 8:00 a.m. on September  ;

'1, revealed _that between 7:00 p.m. on August 31 and 7:00 a.m. on September 1 a total of 326 curies of noble gas and 8 millicuries of Iodine-131 had been released, and that the leak rate )

was decreasing. The maximum concentrations at the site boundary were calculated to have occurred between 9:00 and 10:00 p.m. on August 31. and were 17% of maximum permissible concentration (MPC) of noble gas and 0.7% MPC of Iodine-131. The release rate from 7:00

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p.m. to 7:00 a.m. was approximately 25% of the Technical Specifications release rate limit.

The integrated dose at the site boundary during this period was 0.017 mrad gamma, 0.052 mrad beta, and 0.017 mrem to the thyroid. The licensee also reported that five people initially involved in efforts to operate the valve were contaminated. The maximum level observed was 30,000 CPM (using an RM-14) on the hand of one individual. Initial whole body counts were inconclusive with regard to uptakes due to residual external contamination. The primary contaminating isotope was identified as Iodine-131. ,

i 8709100037 870901 PDR 18rE PNO-V-87-059 PDR

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'h The resident inspectors are following the licensee's continuing efforts to isolate the .; 1 leakage. The nature of the mechanical failure of valve 2HV-9378 and the failure of'the valve l packing are still being determined by the licensee. -

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The licensee is preparing a statement for the news media, but has not decided whether toi j issue it as a press release or to use it only as a response to a query. ,

The above informat, ion is current as of 11:30 a.m. (PDT) on September 1, 1987.

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CONTACT: P, i an J. Tatum F1 / -3745 (714)492-2641 l

l DISTRIBUTION BY 5520: FAX T0:

Date Time Date Time  ;

Chairman Zech E00 R1 INP0 g tv3 I Comm. Roberts AEOD RII NSAC 6/YO  !

Comm. Bernthal PA0 RIII LICENSEE G16'/ )

Comm. Carr SLITP RIV RESIDENT INSPECTOR 61F7 Comm. Rogers NRR HQS. OPERATIONS OFFICER WJ7

.SECY NMSS CA ARM MAIL T0:

PDR 01 DCS(Original)

OGC OIA DOT:(Trans. Only, Applicable State)

ACRS RES GPA RV FORM 211 Revised: 8/19/87 I'

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