ML19276H341
| ML19276H341 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/03/1974 |
| From: | METROPOLITAN EDISON CO. |
| To: | |
| Shared Package | |
| ML19276H306 | List: |
| References | |
| NUDOCS 7910160681 | |
| Download: ML19276H341 (3) | |
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Metropolitan Edison Cc pany Three Mile Island Uuclear Station, Unit 1 Operatinc License Ho. DPP.-50 Ucnroutine 10-Day Report ik-01
~ Infortation ?e aEdin-Septem.ber 5, 6, and 7, 197L, Uncicer.ed Releases of Radioactivity 1.
Description of Incidents:
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September 5 Incident a.
On September 5, 197L, the Control Ro = received an alarn from the particulate =onitor which samples the ventilated air frca the Auxiliary 3nilding.
Health Physics personnel icrediately 133 e and 135Xe, and sampled the Auxiliary Building air.
Only X
85Kr and 88 r in lower concentraticns, were found to be present.
Operations personnel then tried to locate the source of the release, but 147 the tire they were able to begin their search, the radiation level had decreased back to normal.
It was later deter =ined that the cause of the incident van that the loop seal On the Miscellaneous Waste Evaporator Feed Tank had blevn, thereby allowing radioactive gases to escape from the tank and the associated vent header through the bicen loop seal into the auxiliary building sucp.
The loop seal was refilled by an auxilitry operator and the evaporator va:
restarted.
t b.
Septc=ber 6 Incident fdf9 32l On September 6, the came auxiliary building particulate level alarm was received in the Control Rocm.
hcalth Phycies and Operations personnel respcaded as before.
It was determined that the radioactive release had come thrcuch the loop coal on the Miscellanctus Waste Evaporator Fced Tank.
It was found that the - ter in the loop seal had been blown out although the ressen for this was not apparent.
Following the second incident, the eal was once again refilled.
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c.
September 7 Incident Prior to the third incident en Septc=ber 7, a full inventica-tion van begun to d:termine the cauce of the two previous J7 loop scal blovouts, but before taic invcatiCation could bc
of sealant was attributed to a trip of a Misecllaneous Evaporator Feed Tank pu=p in that when the feed pu=p no longer took suctiot on the feed tank, the level increased at a rcte which was sufficJ.ent to increase the air pressure above the liquid in the tank to a point where the loop seal was blevn.
The trip of the evaporator feed pu=p could not, however, be attributed to having caused either of the first two incidents.
d.
General Co==ent Regarding All Three Incidents During the course of the three incidents, no personnel over-exposures occurred although a total of four people vere exposed to liquids and gases of higher than normal radio-activity levels.
2.
Designation of Apparent Cause of Incidents:
Following consultations with the Architect Engineer, it has beea determined that the bleving of the loop seal in the case of all three incidents was due to inadeouate desien, in that the as-built syste= is not capable of handling normal operating pressure transients.
3.
Safety Analysis:
For the following reasons it is believed that the unplanned releases of radioactivity frcu the loop seal did not endanger the health and safety of the public:
During all three incidents, at no ti=e were the releases significan a.
respect to the li=iting conditions of the Technical Specificaticns.
b.
A thorough =onitoring of the four station personnel directly exposed to the releases shoved no detectable levels of ingested radioactive =aterial due to these incidents.
This, together with a review of the conditions to which they were subjected, has resulted in a deter =ination that these four ind! ' duals were not exposed to har=ful levels of radioactivity; and for all practical purposes, it is i=possible for the public to have been exposed to radiation which was = ore intense than this.
4.
Corrective Actions:
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In addition to those carrective actions =entioned in part 1. above, the overflow leg of the loop seal was plugged i==ediately following the Septenber 7 incident; and this plug vill remain in place until design modifications of the seal have been co=pleted (described in section 5. belov); cnd any overpressure in the feed tank vill be relieved to the vent header which is valved to the feed tank during evaporator operation.
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s 5
Preventative Action:
The Plant Oparaticn: ?.evicv Cc=ittee (FCP.C) convened after each of the three incidents and, together with the Stc.tien Superintendent, approved of all corrective actions previously described in this report.
In additien, FC?.C recc= ended that preventr.tive action be taken to redesign s.i sciify the 1 cop seal piping and valve system in such a way the.t 'cicvcut, siphoning, and backsurce vill be prevented while overflev prctecticn of the evaporator vill still be afforded.
The Station Superintendent concurred with"these reco=endations and has taken steps to ensure their ec=pletion.
It is presently anticipated that =ciificaticn of the loop se_al vill be executed shortly after cc:pleticn of the required design studies.
6.
Failure Data:
Not cpplicable.
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