United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 91-23: Accidental Radiation Overexposures to Personnel due to Industrial Radiography Accessory Equipment Malfunctions

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
               OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
                            WASHINGTON, D.C. 20555

                               March 26, 1991


Information Notice No. 91-23:  ACCIDENTAL RADIATION OVEREXPOSURES TO 
                                   PERSONNEL DUE TO INDUSTRIAL RADIOGRAPHY 
                                   ACCESSORY EQUIPMENT MALFUNCTIONS 

Addressees:

All Nuclear Regulatory Commission (NRC) licensees authorized to use sealed 
sources for industrial radiography.

Purpose:

This information notice is being issued to alert licensees to recent 
radiography incidents involving both extremity and whole body overexposures 
of radiographers.  These occurred during industrial radiographic operations 
as a result of:  (1) not surveying a radiographic exposure device and source 
guide tube after each exposure; or (2) using either a magnetic or 
non-magnetic stand for applications that applied stresses exceeding the 
limits of the stand.  It is expected that licensees will review this notice, 
distribute it to responsible staff, and consider actions, as appropriate, to 
avoid similar problems.  However, suggestions contained in this information 
notice do not constitute any new NRC requirements, and no written response 
is required.

Description of Circumstances:

The following cases are recent events reported to NRC that have resulted in 
radiation overexposures to radiographers and radiography assistants as a 
result of improper handling of radioactive sealed sources and inattention to 
radiation safety procedures.

Case 1:  A radiographer had been performing exposures of welds at the base 
of a 300,000 gallon waste storage tank, with a radiography camera equipped 
with a 14-foot guide tube.  A tungsten collimator had been positioned on the 
end of a guide tube that was clamped to a stand that was magnetically 
attached to the tank wall.  After cranking out the 80-curie iridium-192 
(Ir-192) source for an exposure approximately 10 feet above the base of the 
tank, the radiographer heard the collimator fall.  After straightening out 
the guide tube, the radiographer fully retracted the cable, and consequently 
thought that the source was in the shielded position of the camera.  
Subsequently, the radiographer removed his dosimetry, picked up a survey 
instrument, walked up to the end of the source guide tube and removed the 
collimator, without observing the meter reading.  As he was unscrewing the 
nozzle of the guide tube, the source fell to the ground.  The radiographer 
immediately left the area, and notified the proper authorities.  Exposure 
estimates to the radiographer, based on source activity and exposure time 
estimates, are 8.9 rem whole body, and 1070 rem to the right hand.

9103200074 
.

                                                            IN 91-23
                                                            Page 2 of 3 
                                                            March 26, 1991 


Case 2:  A radiographer and his assistant were performing radiographic 
exposures of welds on a 48-inch diameter tank.  After the sixth exposure, 
the radiographer left the immediate area to load film in a belt.  While the 
radiographer was away, the assistant set up the seventh exposure and cranked 
out the source.  The assistant had turned the crank about two or three times 
when he saw that the magnetically mounted stand, that held the guide tube 
near the exterior of the tank, had fallen.  When the stand fell, the 
assistant's personnel dosimeter (chirper) began to alarm, so he quickly 
cranked the source back into the shielded position.  Because his chirper 
stopped alarming, he thought that the source was in the shielded position, 
so he did not survey the area (the licensee later reported that the chirper 
was found to be malfunctioning due to a shorted ground wire).  Instead, he 
walked over to the tank, repositioned the magnetic stand and source guide 
tube with his right hand, and returned to the camera to proceed with the 
exposure.  When he cranked out the 50-curie Ir-192 source, he noted that his 
chirper did not alarm, so he looked at his pocket dosimeter and noticed that 
it was off scale high.  When the radiographer returned, the assistant told 
him what had happened and that his pocket dosimeter had gone off scale.  The 
assistant told the radiographer that he did not think he had received an 
overexposure, but that he thought his pocket dosimeter was off-scale because 
he had bumped it earlier. The radiographer and his assistant continued to 
work and did not inform the Radiation Safety Officer of the incident until 
the assistant's hands showed clinical signs of radiation injury.  From 
reenactments, clinical observations, and calculations, the overexposure to 
the assistant radiographer's hand was estimated to be between 1500 and 3000 
rem.  The attending physician stated that amputation of one or more fingers 
could be necessary.  The whole body dose to the assistant, as measured by 
his TLD, was 365 millirem.  

Case 3:  This radiographic operation involved the use of an 80-curie Ir-192 
source.  After completing two radiographs of a pipe weld, an assistant 
radiographer disassembled the equipment in order to move the exposure device 
to another location.  While doing this, he removed the source guide tube and 
draped it around his neck so that his hands would be free to carry the 
remaining equipment approximately 50 feet.  As he removed the guide tube 
from around his neck, he noticed that the sealed source fell from the tube 
to the ground.  The assistant notified the radiographer, who telephoned the 
company owner and, following his direction, successfully retrieved the 
source to a shielded position within the exposure device.  The 
radiographer's film badge was immediately sent for processing (the assistant 
radiographer was not wearing a dosimeter and was immediately sent to a 
hospital for a medical examination).  The cytogenetic studies revealed 
equivalent whole body doses of 17 rem for the radiographer and 24 rem for 
the assistant.  The assistant developed an area of redness on the left side 
of his neck, which later showed signs of more significant damage to skin 
tissue in an area approximately 10 centimeters in diameter.  The physician 
determined that the observed effect corresponded to an overexposure to the 
skin of 5000-7000 rem.  There were no medical effects observed for the 
radiographer.
.

                                                            IN 91-23
                                                            Page 3 of 3 
                                                            March 26, 1991 

Discussion:

All licensees are reminded of the importance of ensuring the safe 
performance of licensed activities, in accordance with NRC regulations, 
requirements of their licenses, and accepted health physics practices.  The 
aforementioned cases illustrate: the lack of radiation surveys following the 
retraction of a sealed source; failure to wear a direct reading pocket 
dosimeter and either a film badge or TLD; failure to personally supervise an 
assistant radiographer while using radiographic exposure devices; the 
improper use of a magnetic or non-magnetic stand that cannot hold the weight 
of the intended equipment (such as a 12-pound collimator); the necessity of 
consistently following standard operating and, when necessary, emergency 
procedures; and the need to understand the significance of radiation doses 
that result from the misuse of large radiographic sources.  Sealed sources 
for radiography are capable of delivering significant unintended exposures 
to radiographers, assistants, and members of the general public, when source 
management procedures are not followed.

Although it might seem obvious that common sense would prevent radiation 
workers from picking up highly radioactive sources or guide tubes that might 
inadvertently contain a dislodged radiographic source, the number of 
unplanned radiation exposures of this type indicates that "common sense" 
cannot be counted on, in such a situation.  Licensees are responsible for 
ensuring the safe performance of licensed activities in accordance with NRC 
regulations and the terms of their licenses.  In so doing, licensees should 
not only provide adequate training, but should also exercise close 
supervision over their employees, to ensure compliance with procedures and 
with NRC or any other applicable requirements.  All workers should 
understand the consequences of improperly handling a radiographic source 
containing large quantities of Ir-192.  Such improper handling can cause a 
significant, undesired, radiation dose to both the whole body and 
extremities, and can easily result in the amputation of several fingers, the 
development of a tumor, or death.

No written response is required by this information notice.  If you have any 
questions about this matter, please contact the appropriate regional office 
or this office.




                                     Richard E. Cunningham, Director
                                     Division of Industrial and 
                                       Medical Nuclear Safety
                                     Office of Nuclear Material Safety
                                       and Safeguards

Technical Contact:  Cynthia G. Jones, NMSS
                    (301) 492-0629

Attachments: 
1.  List of Recent NMSS Information Notices
2.  List of Recent NRR Information Notices
.
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