ML19276H328
| ML19276H328 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/14/1974 |
| From: | METROPOLITAN EDISON CO. |
| To: | |
| Shared Package | |
| ML19276H306 | List: |
| References | |
| RO-50-289-74-03, RO-50-289-74-04, RO-50-289-74-3, RO-50-289-74-4, NUDOCS 7910160670 | |
| Download: ML19276H328 (2) | |
Text
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?!c tropolitan Edison Compan; Threc 7 tile Island Nuclear Station, Unit 1 (ntI-1).
Docket No. 50-289 O perating License DPR-50 Supplement to Nonroutine 10-Day Reports 74-02, 03, and 04
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Supplementary Information on Threc Unplanncd Relcases of Radioactive Material Occurring on October 6, 8, and 9-10,1974 -
1.
Description of Releases
_0ctober 6
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1.
For the first release, the average release rate was <2<fx 10 3
3 m /sec. and the ca:<icu c. release rate was ji.R x,101 m /sec.
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2.
For the second release, the average release rate was -id x 18 3
3 m /sec and the caximum release rate was Wx 141 m /sec.
_0ctober 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 f rom d1f ferential pressure readings on the Low Pressure Vent 11eader.
These readings were not available when the telegram was sent.
October 9-10 The average release rate uns S.3 x 103 3
m / sac. and the caximum relesne 6
3 m /33c, rate was 2.92 x 10 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 perforced 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 Reicase
_0ctober 6
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October 8 This relense involved the 1.oop Scal of-the Reactor Coolant (RC)1[aste Evaporator Storanc Tank and not the !!isec11ancous 11aste Evaporator 7910160[79
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2 Storage Tank; however, botli Loop Scalu were cut cnd plugged because of a suspected design problem which.was first identified on the Loop Seal of the Miscellaneous b'aste Evaporator Storage Tank (see Non-routina 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 nadio-active Uaste Systcas.
October 9-10 Julether or not there was a loose plug on-the Loop Seal of the RC Waste Evaporator Feed Tank cannot be verified; but a cracked Rupturc 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 frca 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 Engince is in the process of proposing a design modification; and with regard to the written report that has been prepared, it is under revisi.
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