ML19261F234
| ML19261F234 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/14/1974 |
| From: | METROPOLITAN EDISON CO. |
| To: | |
| Shared Package | |
| ML19261F231 | List: |
| References | |
| 74-02, 74-03, 74-04, 74-2, NUDOCS 7910250658 | |
| Download: ML19261F234 (2) | |
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ENCLOSURE (1)
Metropolitan Edison Company Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Docket No. 50-289 O perating License DPR-50 Supplement to Nonroutine 10-Day keports 74-02, 03, and 04 Supplementary Information on Three Unplanned Releases of Radioactive Material Occurring on October 6, 8, and 9-10,1974 1.
Description of Releases October 6 1
1.
For the first release, the average release rate was 2 3 x 10 3
b m /sec. and the maximum release rate was 5.74 x 101 m /sec.
2.
For the second release, the average release rate was 1.9 x 101 3
3 m /sec. and the maximum release rate was 5.74 x 101 m /sec.
October 8 The average release rate was 5 x 103 3
m /sec. The maximum release rate was 1.9 x 104 3
m /sec., which is lower than the value reported in our telegram of October 9 (4.2 x 104 m3/sec.). This lower value is con-sidered to be more accurate because it was determined from differential pressure readings on the Low Pressure Vent Header. These readings were not available when the telegra a wcs sent.
October 9-10 The average release rate was 8.3 x 103 3
m /sec. and the maximum release rate was 2.92 x 104 =3/gce, The duration of the release was 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, which differs from the value reported in our telegram of October 11 (2.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) because a detailed investigation of the release could not be performed in the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> allowed for sending the telegram.
2.
Apparent Cause of the Release October 6 October 8 This release involved the Loop Seal of the Reactor Coolant (RC) Waste Evaporator Storage Tank and not the Miscellaneous Waste Evaporator 1481 208 7910250 h N
Storage Tank; however, both Loop Seals were cut and plugged because of a suspected design problem which was first identified on the Loop Seal of the Miscellaneous Waste Evaporator Storage Tank (see Non-routine 10-Day Report 74-01, dated October 3,1974). It should also be noted, however, that it has been determined that this design problem does not exist on any of the other loop seals of the Radio-active Waste Systems.
October 9-10 Whether or not there was a loose plug on the Loop Seal of the RC Waste Evaporator Feed Tank cannot be verified; but a cracked Rupture Disc was found and is thought to have contributed to the release.
Although this was in part a cause of the release, it cannot be verified that this was the sole cause.
3.
Analysis of Releases 4.
Corrective Action It should be noted that collected leakage from various sources into the Reactor Coolant Drain Tank (RCDT) had given rise to a higher than normal concentration of radioactive gases in the vent header that is common to the RCDT and the evaporator storage tanks. The leaks have been repaired.
Regarding the design problem with the two loop seals, the Architect Engineer is in the process of proposing a design modification; and with regard to the written report that nas been prepared, it is under review.
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