ML19294A512

LER#78-025/03L-0 on 781031:condensate Storage Tank Was Leaking Due to Galvanic Corrosion.Leak & Other Weak Spots Were Patch Welded

ML19294A512
Person / Time
Site:	Oyster Creek
Issue date:	11/30/1978
From:	Ross D JERSEY CENTRAL POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19294A511	List: ML19294A510 ML19294A512
References
LER-78-025-03L, LER-78-25-3L, NUDOCS 7812070220
Download: ML19294A512 (3)

Text

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EVENT D ATE 74 ?b REPOAT DATE b3 G1 DOCK ET NuvSER EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h a 2 On October 31, 1978 a leak was discovered at the base of the condensate j

o 3  ; storage tank. The_ water in the tank at the time had an activity con-  ;

o 4 l centration of 4.30 E-05 pCi/ml. After the tank was emptied and the bot- l 0 5 l tom cleaned, a small hole (0 5 cms. dia.) was found. Isotopic analyses l gs j made of core samples taken at distances of four and twelve feet from o 7 [ the tank to a depth of twenty-five f eet showed no significant amount of l o y  ; activity above background. The event has minimal safety significance.  ;

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44 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i O lThe cause of the failure is attributed to calvanic corrosion from be-

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neath the tank. The tank was emptied and the area of the leak was l patch welded. Patches were also welded over other areas where wall thinn- l

, 3 ing was made evident by ultrasonic means. An engineering evaluation l

[i ;4 ] [will be made to determine an appropriate corrosion protection scheme. I 7 8 9 80 STA S  % POWE R OTHER STATUS ISCOV RY DISCOVERY DESCRIPTION i 5 lHl@ l0l0l0l@l NA l B l@l Personnel Observations ACTIVITY CO TENT RELEASE AMOUNT OF ACTIVITY LOCATION OF RELE ASE W [_L_j @D OF RELEASE lMl@lSmall l Tank to around l 7 8 9 to 11 44 45 80 PERSONNEL EXPOSURES NUMBER TYPE DE SCRIPTION i 7 l0]Ol0l@lZl@l NA l PERSONNE L INJURIES NUVRER DESCmPTION@

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i y Maison Avenue a: Punen Bcd Road Morr:stown, New Jersey 07960 (201)455 4203 OYSTER CREEK NUCLEAR GENERATING STATION Forked River, New Jersey 08731 Licensee Event Report Reportable Occurrence No. 50-219/78-25-3L Report Date December 1, 1978 Occurrence Date October 31, 1978 Identification of Occurrence Unmonitored release of radioactive water from the base of the condensate storage tank. This event is considered to be a reportable occurrence as defined in the Technical Specifications, paragraph 6.9.2.b.4.

Conditions Prior to Occurrence The plant was shut down for a scheduled refueling / maintenance outage.

Reactor subcritical.

Reactor mode switch locked in refuel.

All control rods fully inserted.

Source range monitors < 40 cps.

Cavity flooded.

Reactor coolant 93 F.

Description of Occurrence On October 31, 1978, at approximately 0700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br />, a leak at the base of the condensate storage tank was discovered. Following this observation, action was initiated to correct the problem. The water in the tank was transferred to the hotwell and to the radwaste building. The bottom of the' tank was cleaned and inspected. Repair commenced approximately five days after the discovery of the leak and completed on November 11, 1978.

At approximately 1330 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.06065e-4 months <br />, on October 31, 1978, a sample of the water in the condensate storage tank was collected. An isotopic analysis was run and a concentration of 4.30 x 10-5 uti/m1 of activity was detected.

Apparent Cause of Occurrence The cause of the event is component failure which is attributed to galvanic corrosion from beneath the tank.

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• Reportable Occurrence No. 50-219/78-25-3L Page 2 December 1, 1978 Analysis of Occurrence Based on the change of water level in the condensate storage tank and the size of the hole (approximately 0.5 cm in diameter), a very small amount of wa~ter was released. On November 6, 1978, at approximately 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br />, a sample of the sand beneath the condensate storage tank was collected directly under the failure. An isotopic analysis indicated a concentration of 7.38 x 10-1 pCi/ml. In addition to the sample beneath the condensate storage tank, core samples were taken four feet and twelve feet f rom the tank on November 20, 1978. These samples were taken at ground elevation, five feet, ten feet, fifteen feet, and twenty feet below the surface. No significant amount of activity was detected above background. The safety significance of this occurrence is, therefore, considered to be minimal.

Corrective Action Upon discovery that the condensate storage tank was leaking, the water was transferred to the hotwell and to the radwaste building. The area of the leak has been patch welded. The entire bottom <f the storage tank was spot checked by ultrasonic testing and other locations were identified where wall thinning was evident. Patches were welded over each of the locations. An engineering evaluation will be performed to determine an appropriate corrosion protection scheme.

Failure Data Condensate Storage Tank Type - Vertical Conical Roof Nominal Capacity - 525,000 gallons Dimensions Diameter - 45.0 feet Height - (Cylindrical Portion) 45.0 feet Material - Aluminum Alloy