05000346/LER-1981-031-03, /03X-1:on 810512,following Reactor Trip,Rcs Radioiodine Content Exceeded Limit.Caused by Gas Leakage Through Fuel Cladding.Levels Decayed Off Below Limits.Tech Spec Revision Being Evaluated

/03X-1:on 810512,following Reactor Trip,Rcs Radioiodine Content Exceeded Limit.Caused by Gas Leakage Through Fuel Cladding.Levels Decayed Off Below Limits.Tech Spec Revision Being Evaluated

ML20009D653
Person / Time
Site:	Davis Besse
Issue date:	07/13/1981
From:	Rowland M, Stotz J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20009D650	List: 05000346/LER-1981-031, Forwards LER 81-031/03X-1 05000346/LER-1981-031-03, /03X-1:on 810512,following Reactor Trip,Rcs Radioiodine Content Exceeded Limit.Caused by Gas Leakage Through Fuel Cladding.Levels Decayed Off Below Limits.Tech Spec Revision Being Evaluated
References
LER-81-031-03X, LER-81-31-3X, NUDOCS 8107240255
Download: ML20009D653 (2)

LER-1981-031, /03X-1:on 810512,following Reactor Trip,Rcs Radioiodine Content Exceeded Limit.Caused by Gas Leakage Through Fuel Cladding.Levels Decayed Off Below Limits.Tech Spec Revision Being Evaluated

Event date:
Report date:
3461981031R03 - NRC Website

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l (NP-33-81-37) On May 12,1981 at 1457 hours0.0169 days <br />0.405 hours <br />0.00241 weeks <br />5.543885e-4 months <br /> following a reactor trip, a Reactor 3 2 f-T~} l Coolant System (RCS) samp1' was collected in accordance with Technical Speci l

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O TOLEDO EDISON COMPANY DAVIS-BESSE. NUCLEAR POWER STATION UNIT ONE PACE 2 SUPPLEMENTAL INFORMATION FOR LER NP-33-81-37 The dose equivalent I-131 exceeded 1.0 uCi/gm at 2037 hours0.0236 days <br />0.566 hours <br />0.00337 weeks <br />7.750785e-4 months <br /> on May~ 12, 1981, and was below that limit at 0350 hours0.00405 days <br />0.0972 hours <br />5.787037e-4 weeks <br />1.33175e-4 months <br /> on May 13, 1981. The total time dura-tion was approximately 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />. The maximum level was 1.52 uci/go.

Specific Activity Analysis:

Date Time Activity (uCi/gm) Dose Equivalent I-131 5/12/81 0500 0.132 1845 0.94 2037 1.52 1.14 5/13/81 0013

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0350 0.99 0555 0.74 0815 0.16 Designation of Apparent Cause of Occurrence: A reactor trip typically causes an iodine spike in the RCS. This is caused by a slight amount of gas leakage through the' fuel rod cladding due to transient conditions. The gas leak is a result of in-creased compression of gas by the contracting cladding. Any small defects would allow some gas to escape.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station 1.arsonnel. There was no venting of containment gases until the levels had decayed. The highest levels found in any sample were still well below the allowa-ble limit of 60 uCi/gm per Figure 3.4-1 of Technical Specification 3.4.8.

Corrective Action

A corrective action is not applicable. Iodine spikes are typical following a reactor trip. No damage is indicated to the fuel. Monitoring of I-131 level was continued until it dropped below Technical Specification limit of 1 uCi/gm.

At 0555 hours0.00642 days <br />0.154 hours <br />9.176587e-4 weeks <br />2.111775e-4 months <br />.on May 13, 1981, the level dropped to.74 uCi/gm. A Technical Specifi-cation revision to change the limit is being evaluated per Facility Change Request 81-163.

Failure Data: There have been two previous reports of high iodine levels - see Licensee Event Reportis NP-33-80-114 (80-088) and NP 33-81-15 (81-016).

1

- LER #81-031 O