ML20237G869
| ML20237G869 | |
| Person / Time | |
|---|---|
| Site: | 05000000, San Onofre |
| Issue date: | 06/23/1987 |
| From: | Scarano R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Novak T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| Shared Package | |
| ML20237F649 | List: |
| References | |
| FOIA-87-377, RTR-NUREG-0090, RTR-NUREG-90 NUDOCS 8709030006 | |
| Download: ML20237G869 (4) | |
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ech a J oui MEMORANDUM FOR:
Thomas M. Novak, Director Division of Safety Programs, AEOD FROM:
Ross A. Scarano Director Division of Radiation Safety & Safeguards
SUBJECT:
POTENTIAL ABNORMAL OCCURRENCE REPORT ON A 512 rem HAND EXPOSURE f
By memo, dated June 17,1987(J.B.MartintoE.L. Jordan),RegionY responded to AE00's May 27th request for input to the first quarter Abnonnal Occurrence Report to Congress. The June 17th memo stated that Region Y would be providing a separate write-up covering the potential A0 involving the San Onofre, Unit 3 overexposure from a small " hot particle." The enclosed A0 write-up is provided for AE0D's consideration. The San Onofre event has been written as an A0, pending staff consensus and Commission approved guidelines j
for handling such events.
Should you have questions regarding the enclosed write-up, please contact Frank Wenslawski of my staff.
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Ross A. Scarano, Director j
Division of Radiation Safety & Safeguards l
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P. Bobe. AE0D/TPAB i
F. Congel, NRR/DREP l
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1 POTENTIAL A0 SCE 87 -
OVEREXPOSURE OF A MAINTENANCE WORKER'S HAND Date and Place During maintenance activities at San Onofre Unit 3 during October 1986, a l
licensee mechanic received an exposure to his right hand on the order of j
512 rem. The exposure was not reported until December 12, 1986. San Onofre Unit 3 is a Combustion Engineering designed pressurized water reactor (PWR) operated by Southern California Edison Company (the licensee) and located in San Diego County, California.
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Nature and Probable Consequence On December 12, 1986, the licensee reported that an overexposure of a l
worker's right hand may have occurred during the month of October,1986.
l The licensee did not discover the possibility of an overexposure occurring l
until December 11, 1986, because an error in their computer software had I
truncated the number reported to them electronically b l
The report was followed by Licensee Event Report (LER)y their vendor.86-015 (ref. 1)
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which detailed current information about the event but indicated the l
l investigation was continuing. The licensee issued Revision 1 of LER 86-015 J
(ref. 2) on February 22, 1987, reporting their conclusion that the overexposure did not occur. The licensee issued Revision 2 of LER 86-015 (ref. 3) on May 7,1987, stating that it had not been possible to detennine whether or not an exposure occurred and providing their estimate of the
" dose equivalent" to be 5.6 rem in this instance.
NRC inspections during the periods December 15, 1986; January 12-16, 1987; March 16-20, 1987; and May 8-14, 1987, (refs. 4 & 5) found that no valid basis existed for discrediting or adjusting downward the reported dose of 511.99 rem. Highly radioactive irradiated fuel fragments capable of delivering the dose were known to exist at the site and could have been deposited in the systems on which the mechanic worked. The radiation and contamination surveys performed during the mechanics work were routine, not documented and performed by technicians untrained in methods needed i
to detect fuel fragments. The physical examination of the worker did not occur until two months after the potential event. No physiological effects to the hand were observed. Cytogenetic findings, although inconclusive, I
could be consistent with a partial body exposure of the indicated magnitude.
The physically small irradiated fuel fragments that have been observed at San Onofre Nuclear Generating Station and at other utilities can be intensely radioactive particles,1E-3 to 1E+3 microcuries, yet are very i
difficult to detect. The contact dose rate of a 1 microcurie particle can j
range from 3 to 9 rem /hr to one square centimeter of skin, depending on the age of the particle, yet it will be almost undetectable with commonly used hand held radiation survey instruments in moderate background radiation areas unless the instrument is within a few centimeters of the particle.
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-The particles are primarily beta emitters, beta maximum 3.5 MeV, with only l
an insignificant gamma component. They appear to present an acute exposure l
hazard to small areas of the skin at high doses; i.e. 200-600 rem, erythema i
(reddening); 800-1100 rem, dry desquamation (scaling); 1300-2000 rem, wet l
i desquamation(blisters); 2000-2500 rem, ulceration. As the skin is relatively
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insensitive to radiogenic cancer initiation, the stochastic consequences of particle exposure appear to be minimal.
l Cause The ultimate cause of the exposure appeared to be a failure of the licensee to take action to control the spread of irradiated fuel fragments within I
primary plant and radioactive waste systems and to protect workers from the consequences of exposure to the particles after their discovery in late 1985 during fuel reconstitution. Licensee management appeared to have adequate-warning that a hazard could exist but failed to fully implement action to ameliorate its consequences outside their fuel handling building until December 1985.
Action Taken To Prevent Reoccurrence I
Licensee _ - The licensee began a station-wide program to control irradiated i
l fuel fragments in December 1986. This included general employee training on the nature of the particles and their hazards, specific training of health physics technicians in the characteristics of the particles and methods needed to detect and control them, institution of a task force to recomend and implement action to minimize production and movement of particles, and procurement and use of highly sensitive whole body beta contamination detectors. The licensee also implemented, in January 1987, specific radiation protection procedures to establish a three-zone control approach to protect workers from the particle hazards.
Nuclear Regulatory Commission - A special inspection of the event was conducted at San Onofre on the dates noted above. Additionally, a Region V branch chief and a consulting physicist visited the dosimetry vendor to review the processing of the TLD badge in question. The Region also i
obtained further assistance from a consulting physician and a contract laboratory. The inspection results were forwarded to the licensee in a letter dated April 13, 1987.
An enforcement action is presently being prepared by the NRC staff.
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REFERENCES,
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1.
Letter from H. E. Morgan, San Onofre Station Hanager, Southern Californ'ia Edison Company; to U.S. Nuclear. Regulatory Commission, Document Contral Desk; dated January 12, 19B7.
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Letter from H. B. Ray, Vice Peer.ident and'Sitt Manager, Southern California Edison Company; to U'5.Juclear Regulatory Comission, Document Control Desk; dated February 42, 1987, Letter from H. B. Ray, hice President and Site Manay!or, Southern Califcrnia 3.
Edison Company; to U.S Nuclear Regulatory Commission, Document Control Desk; dated May 7.
1987.
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Letter from R. A. Scarano, Director, Division of Radiation Safety and Safeguards, USNXC, Region V; to K. P. Baskin, Vice President, Southern California Edi d n Company; dated April 13, 1987; forwarding inspection report number 50-362/86-37.
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Letter from R. A. Scarano, Director Division of Radiation Safety and Safeguards, USHUC, elegion.V; to K. P. Baskin, Vice President, Southern California Edison Company; dated May 28, 1987, forwarding inspection report number 50-362/87-13.
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