05000280/LER-1981-033-03, /03L-0:on 810822 & 23,post-reactor Trip Specific Activity Samples of RCS Indicated Dose Equivalent I-131 Level Greater than Tech Spec Limit.Caused by Fuel Element Defect in Reactor Core Resulting in Iodine Spike

/03L-0:on 810822 & 23,post-reactor Trip Specific Activity Samples of RCS Indicated Dose Equivalent I-131 Level Greater than Tech Spec Limit.Caused by Fuel Element Defect in Reactor Core Resulting in Iodine Spike

ML20010H238
Person / Time
Site:	Surry
Issue date:	09/15/1981
From:	Joshua Wilson VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20010H231	List: 05000280/LER-1981-053-03, /03L-0:on 810816,shaft of Standby Pump 2-SW-P-10B Found to Be Rotating Backwards Due to Failure of Check Valve L-SW-108 to Seat Properly.Caused by Wear Resulting in Excessive Play & Binding in Disc ML20010H230
References
LER-81-033-03L-04, LER-81-33-3L-4, NUDOCS 8109240254
Download: ML20010H238 (3)

LER-1981-033, /03L-0:on 810822 & 23,post-reactor Trip Specific Activity Samples of RCS Indicated Dose Equivalent I-131 Level Greater than Tech Spec Limit.Caused by Fuel Element Defect in Reactor Core Resulting in Iodine Spike

Event date:
Report date:
2801981033R03 - NRC Website

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On August 22 and 23, post reactor trip specific a.:tivity samples of the reactor i

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limit. Since the integrity of the steam generator tubes was maintained and the J

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activity remained below the TS-3.1.D.3 limit, the health and safety of the public 1

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cAusE DESCRIPTION AND CORRECTIVE ACTIONS

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50-280 REPORT NO:

81-033/03L-0 EVENT DATE:

3-22-81 TITLE OF EVZhT:

JJQGH I-131 IN RCS 1.

DESCRIPTION OF EVENT

At 0410, on August 22,1981, following a reactor trip from 100% power, the specific activity sample of the reactor coolant showed a peak dose equiva-lent I-131 level of 2.73 microcuries/ce, exceeding the T.S.3.1.D.2 limit of < l.0 microcuries/ce, The dose equivalent I-131 returned to within the T.S. limit at 2115 and remained within the limit until 0303 on August 23.

The second peak measured 1.01 nicrocuries/cc. This event is reportable per T. S. -6. 6.2. b (2) and TS-3.1.D.4.

2.

PROBABLE CONSEQUENCES:

The limitations on the specific activity of the primary coolant ensure that the ecsulting 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> doses at the site boundary will not exceed an appro-priately small fraction of 10CFR 100 limits following a postulated steam generator tube rupture. Since the dose equivalent 1-131 peak was below the technical specification upper limit of 10 microcaries/ce, the reactor coolant gross activity was below the value analyzed in t he FSAR for a tube rupture and 1% failed fuel. Therefore, the health and safety of the public were not af f ect ed.

3.

CAUSE OF EVENT

The iodine spike was caused by known, yet not specifically located, fuel element defects in the reactor core. Post trip conditions enhanced the release of fission products, specifically I-131, to the reactor coolant system, causing an increase in the coolant specific activity level.

4.

I!BIEDIATE CORRECTIVE ACTION:

The immediate corrective action was to implement the actions requirs by T.S.

table 4.1-2B.

Specifically, the level of dose equivalent 1-131 was mao! yred every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> until the level returned to less than 1.0 microcurie /ce, at which time the reactor was restarted and returned to power.

5.

SCHEDULED CORRECTIVE ACTION:

No further corrective actions will be taken at this time.

6.

ACTIONS TAKEN TO PREVENT RECURRENCE:

The specific activity of the reactor toolant system will continue to be monitored ae required by T.S. table 4.1-2B.

7.

GENERIC IMPLICATIONS:

There nie no generic implications associated with this event.

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.,. v ATTAC101ENT:

PAGE 2 of 2 REPORT NO. 81-033/03L-0 l

SUPPLEMENTAL INFORMATION:

The supplemental information required by T.S.3.1.D.4 "Special Report" is included as follows:

1.

Resctor power history 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> prior to these events August 20,1981 - 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at 100%

August 21,1981 - 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at 100%

August 22,1981 - 0258 Reactor Trip August 22,1981 - 2248 Reactor Startup 2.

Fuel Burnup by core region - as of 2400, August 22,1981; Fuel Batch 4A: 12548 MND/MTU 6B: 12447 MWD /MTU 4C:

25800 MUD /MTU 6C:

22386 MWD /MTU 7A: 17848 MWD /MTU 7B:

16943 MWD /MTU 8A: 1586 MWD /MTU 8B: 1378 MWD /MTU Cycle 6 Burnup - 1364.77 MWD /MTU 3.

Normal letdown prior to trip and dilution to criticality.

Average flow rate of letdown 116 gpm.

4.

No De-gassing operations were performed.

5.

Duration of I-131 spike August 22,1981 - Post Trip sample (0410) 2.73 microcuries/cc 2001 - 1.02 microcuries/cc 2115

.927 microcuries/cc August 23,1981 0303 - 1.01 microcuries/cc 0539

.769 microcuries/cc Duration approximately 18.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.