ML20010F258
| ML20010F258 | |
| Person / Time | |
|---|---|
| Issue date: | 07/15/1981 |
| From: | Cain C, Everett R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML20010F227 | List: |
| References | |
| NUDOCS 8109090538 | |
| Download: ML20010F258 (6) | |
Text
7.
U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT REGION IV REPORT OF INVESTIGATION IE Investigation Report:
81-01 License:
42-17552-01 Priority:
VI Category: E. 2 Mustang Services Company 10222 Georgibelle Houston, Texas 77043 Investigation at:
Mustang Services District Office 3504 South Meridian Oklahoma City, Oklahoma
SUBJECT:
Cesium-137 Sealed Source Lost from Tube Wall Caliper Period of Investigation:
June 26-30, 1981 Inspector:
O_Y bim 7/13 /SI C. L. Cain, Raciation Specialist Oate
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Reviewed by:
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R. J. iiverett, Chief, Materials Raciation Data Protection Section Investigati.
Summary Investigation c, June 26-30, 1981 (Recort No. 81-0J)
Areas Investicate, Investigation of the loss of licensed material consisting of one 1.5-curle c.
'um-137 sealed source used in a tube wall caliper.
The investigation inclut 'd interviews with personnel and involved one hour on site and eight hours off s,'te by one NRC inspector.
Results:
Three violations were identified:
1.
Failure to use or supervise use of licensed material by an autnorized individual in accordance with License Condition 12.
2.
Failure to perform radiation surveys during activities using sealed sources in accordance with License Condition 16.
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Failure to supply appropriate personnel monitoring equipment in accordance with 10 CFR 20.202(a)(1) to personnel using ifcensed material.
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REASON FOR INVESTIGATION The NRC Regiot. IV office was notified by a consultant representing Mustang Services Company at 10:45 a.m. on June 25, 1981, that the licensee was unable to locate a 1.5-curie cesium-137 sealed source last known to be installed in a tube wall calfper at the licensee's facilities in Oklahoma City.
The unshielded source was subsequently found along a highway in Texas.
SCOPE OF INVESTIGATION On June 29, 1981, a Region IV inspector interviewed licensee representatives in Oklahoma City to determine the circumstances relating to the loss of the source.
Various licensee representatives in Houston were contacted by tele-phone during the search for the source and after its recovery.
CONCLUSION The investigation revealed that one member of the public was likely to have received a whole-body dose no greater than 1.4 rem due to the loss.
A licensee employee, who was present at the time of source expulsion from its shielded enclosure, also received an exposure estimated to be less than 600 millirems.
The inspector identified three violations of NRC regulations and license conditions during the investigation.
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i OETAILS i
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A.
Persons Contacted Steve Dunbar, District Manager, Mustang Services Company
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i Steve Smith, Technician Bob Gallagher, Nuclear Sources and Services (licensee consultant)
Con Stone, Plastic Applicators, Inc., Truck Driver Larry Ricketson, Texas Department of Health Resources N. M. Howard, Vice President, Mustang Services Company 3.
Investigation Findings Discussions with the district manager in Oklahoma City on June 29, 1981, disclosed that a 1.5-curie cesium-137 sealed source was last known to l
be installed in a tube wall caliper on June 18, 1981, when the device was mounted in an inspection trailer located at the facilities of the licensee in Oklahoma City., The trailer had been sold to a firm identified as Plastic Applicators in Houston.
Since Plastic Aoplicators had act i
yet been licensed to possess the source, the licensee planned to remove the caliper from the trailer; prior to the new owner taking possession of the tra11er in Oklahoma City, and transporting the trailer to the licensee's Houston facilities.
A former employee of the licensee, who had terminated employment apprtximately a month earlier, was contracted to perform the task of removing the caliper from the trailer, transferring the caliper to a licensee pickup truck, and transporting the caliper to the licensee's i
facilities in Houston.
The technician commenced the dismantlement operation alone at 11:00 p.m.
on June 18.
He had not been supplied with personnel dosimetry for use during the task:
Survey meters were locked within the office to which the technician was unable to gain access.
The technician, who was interviewed by telephone on June 29, stated that he removed and rep 1wd a number of bolts and caliper components during the attempt to free the device frem 1
its mounting.
The source shield plug was later thought to be one of the i
components removed and replaced.
The small encapsulated source, which is
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3/8" in diameter and 1 1/4" long, was suspected to have unknowingly fallen i
into a " belly pan" beneath the caliper and associated pipe handling apparatus.
The belly pan was described as a receptacle recessed below I
trailer floor level for use in collecting debris removed from pipes during the inspection process.
The pan was known to have several large wear holes several inches in length.
The technician stated that the dismounting opera-tion was completed in approximately 30 minutes and that he had left the 4
site bound for Houston by midnight.
The trailer was locked uoan his departure.
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A Plastic Applicators employee transferred the locked trailer from Oklahoma City to the new owner's Houston facilities during the after-noon of June 23.
The truck stopped in Nonr.an, Oklahoma, for engine repairs; Ardmore, Oklahoma, for refueling; and then proceeded to Houston on Interstate Highway 35.
The licensee discovered that the source was not in the caliper on the afternoon of June 24.
The licensee consultant performed radiation surveys of the caliper, pick-up truck, trailer, and the facilities and grounds of the licensee and Plastic Applicators.
The consultant informed the 1
l Region IV office of the loss at 10:45 a.m. on June 25, 1981, and stated that the health departments of Texas and Oklahoma had been notified and were assisting the consultant in a highway search for the lost source.
A Texas Department of Health Resources representative located the source j!
on a bridge near Lewisville, Texas, while perfonning a highway instrument survey at approximately 7:00 p.m. on June 26. The Texas representative stated that the source had fallen onto a structural member of the bridge several feet below the surface of the roadway.
He stated that the dose rate at the bridge surface was 5 mR/h.
The source was retrieved and returned to the licensee's Houston facilities by an employee of the f
consultant.
The source is believed to have fallen through one of the holes in the belly pan of the trailer during transport.
The pickup truck was new, i
had no holes in the bed, and the source would not have likely dropped from the truck, if it had been successfully transferred to it.
Since the Plastic Aoplicators employee, who was driving the truck pulling the trailer, was unaware of the presence of the source, the likelihocd of his being exposed by the source was investigated.
The driver, who was interviewed by telephone, stated that he stood beside the trailer for four hours during the engine repair work in Norman on June 23.
The i
closest estimated distance between the source and the individual during this time was four feet.
Therefore, based upon an exposure rate constant for cesium-137 of 3.6 R/h per curie at one foot, the maximum estimated 3
whole-body dose to the driver was cslculated as follows:
3.6 R
. 1.5 Ci. Ah. (1 ft)2 rem 2 u rem i
h-Ci (4 ft)
R Shielding provided by the aluminum trailer was considered negligible. The driver stated that no other persons were observed near the trailer during transport.
The exposure received by the licensee technician who performed the dis-assembly was conservatively calculated based uoan the assumption that ne stood no closer than three feet frem the source for one hour.
The estimated dose was calculated as 600 mrem.
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The technician was initially employed by the licensee during August 1980 and was given training in radiation safety by the consultant during November 1980.
He had left the permanent employ of the licensee during May 1981.
The technician was not listed on the license as one authorized to use licensed material.
C.
ixit Briefing The Oklanoma City facilities of the licensee were vacated at the time of the investigation except for the district manager whose employment was terminated f'er June 30.
Therefore, an exit briefing was performed by telephone on June 30 with N. M. Howard, Vice President, Mustang Services Company, in Houston.
The inspector outlined three viciations of NRC regulations and license conditions identified during the investigation:
1.
The technician who dismounted the caliper was not listed in License Condition 12 as one authorized to use or supervise the use of licensed material.
2.
Instrument surveys were not performed during activities using a sealed source as prescribed in the license application.
This was identified as a violation of License Condition 16.
3.
Personnel monitoring equipment was not supplied to personnel in accordance with 10 CFR 20.202(a)(1).
The inspector called attention to ID CFR 20.402(b) which requires a written report of the incident te n nd,:mitted to the Region IV office.
The licensee representative s4TM M since the Oklahoma facility had been closed, the licensee p.a ry*
request termination of the license.
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