PNO-III-87-144, on 871123,medical Physicist Received Radiation Exposure of 7.5 Rem While Performing Survey Measurements on Newly Replaced Co-60 Teletherapy Unit.Caused by Physicist Entering Area While Source Exposed
| ML20236T100 | |
| Person / Time | |
|---|---|
| Site: | 03011623 |
| Issue date: | 11/24/1987 |
| From: | Casey C, Mallett B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| References | |
| PNO-III-87-144, NUDOCS 8712010008 | |
| Download: ML20236T100 (1) | |
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PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PHO-111-87-144 Date November 24, 1987 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without c verification or evaluation, and is basically all that is known by the Region III j staff on this date.
Facility: St. Louis University Licensee Emergency Classification:
1402 S. Grand Blvd. Notification of an Unusual Event St. Louis, MO 63104 Alert Site Area Emergency -
License No. 24-04581-19 General Emergency X Not Applicable ,
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6
Subject:
OVEREXPOSURE On November 23, 1987, the licensee reported to Region III (Chicago) that its medical physicist had received a radiation exposure of 7.5 rem while performing survey measurements on newly replaced cobalt-60 teletherapy unit. The overexposure determination was based on the reading-of the individual's thermoluminescent dosimeter (TLD). The applicable exposure linit for this individual is 1.25 rem per calendar quarter.
The exposure occurred October 26, 1987, but the licensee reported that it was initially estimated that the exposure was about 2 rem. The licensee reported that the physicist and the radiation safety officer were attempting to obtain " worst case" radiation measurements.
They overrode the interlock system, intended to prevent the cobalt-60 source from being exposed when the door into the treatment area was open. They then directed the teletherapy beam toward the open doorway. The exposure occurred when the physicist reentered the treat.nent area to reposition the device, while the source was still exposed. j ,
When the licensee received the TLD results on November 20, 1987, a reenactment was monducted 1 which determined the physicist was exposed to the radiation beam for about 10 seconds instead of the 2 seconds previously calculated. Besides the whole-body TLD, a ring TLD which the physicist had in his pants pocket, registered 9.08 rems. i The radiation safety officer's whole-body TLD measured an exposure of 60 millirem.'
- No other persons were in the vicinity when the beam was exposed, according to the licensee, q i
The licensee did not have the TLDs processed immediately after the incident, and did not receive '
the results until November 20. The incident was reported to the NRC on November 23, 1987.
The State of Missouri has been notified of the incident.
Region III received initial notification of this event from the licensee at 4:20 p.m.,
November 24, 1987.
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Jhip information is current as of /#Iddh"dSr7 2 p.m , l November CONTACT: C. Cas y (FTS 388-5734) B. Mallett (FTS 388-5612) Qt/[,,4 v
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