ML20041C203
| ML20041C203 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/20/1982 |
| From: | Barrett L, Conte R, Fasano A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE), Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| PNO-TMI-82-003A, PNO-TMI-82-3A, NUDOCS 8202260331 | |
| Download: ML20041C203 (2) | |
Text
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50320-820219 February 20, 1982 o
PRELIMINARY HOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--FN0-TMI 82-03A This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance.
The information is as initially received without verifi-cation or evaluation and is basically all that is known by NRC staff on this date.
Facility: Metropolitan Edison Company Licensee Emergency Classification:
Three Mile Island, Unit 2 X
Notification of Unusual Event Docket No. 50-320
Subject:
APPARENT 0XYGEN DEFICIENT ATMOSPHERE IN THE REACTOR BUILDING (UPDATE)
An unusual event was declared by the licensee at 5:26 PM (previously reported as 5:25 PM) on February 19, 1982.
This occurred subsequent to two reactor building (RB) entries at 9:03 AM and 1:45 PM (same day) which indicated: apparent local low oxygen content (lowest instrument reading 12% - normal concentration readings are 20.5 - 21%) based on portable instruments; combustible gas mixture at 347' level; and a grab sample analysis from the 305' level of 1-1.5% H2 with no detectable C02 and CO, and 19% + 2% 0.
2 Purging of the RB was continued. Between 5:00 PM and Midnight analyses of the. RB atmosphere samples obtained via the air sampling system and portable monitor indications of the purge exhaust trains indicated normal atmospheric ruults of 20-21 % 02 and 78% N2 with no detectable combustible gas.
During an RB entry, between 12:33 AM and 12:52 AM on February 20,1982, grab air samples and portable monitors indicated normal readings except as noted below.
One of two types of portable gas mo11 tors (Gas Tech) alarmed on low oxygen upon entry into the airlock and continued to alarm throughout the entry.
However, this type instrument was being used to monitor combustible gas readings onl y.
The other type of monitors (two-Edmonts, which has seperate oxygen and combustible gas meters) indicated normal 02 concentration and no detectable combustible gases.
It was also determined that the Edmont detector alarmed and indicated abnormal readings simultaneously with radio tranceiver activation by technicians in the RB.
The operability of the Gas Tech is being reviewed.
Data collection of RB atmosphere and purge train exhaust continued throughout the night with no abnormal analysis results.
At 10:00 AM, today the purge system was shutdown and data collection continued via the installed air sampling system. No abnormal readings were detected.
The unusual event was secured at 2:04 AM, today.
The licensee intends to make another RB entry at 6:00 PM today to obtain grab air samples and assess gas monitor instrument performance. Another entry is planned for Monday, February 22, 1982, after the purge system has been shutdown for two days, to attempt to simulate conditions on the morning of February 19, 1982 Media interest occurred beceuse of licensee notification to local officials and the licensee's issuance of a press release.
NRC responded to inquiries.
The Commonwealth of Pennsylvania, EPA and DOE were infonne m g/
,a The NRC plans to continue monitoring events as Ahey occur.
An Qt report will be issued on Monday, February 22, 1982, subsequentiM the;,pla.nned try.
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PNO-TMI-82-03 A February 20, 1982 The NRC TMI Program Office received notification of this occurrence by monitoring events as they occurred and this information was current as of 1:00 PM.
A 10 CFR 50.72 report was not needed since NRC manning of the ENS circuit was alreadj' initiated etwe 5:00-5:20 PM on Februqry 19, 1982.
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