United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 81-13: Jammed Source Rack in a Gamma Irradiator

                                                              SSINS: 6870  
                                                              Accession No: 
                                                              8103300371   
                                                              IN 81-13     

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C. 20555
                                     
                               April 14, 1981

INFORMATION NOTICE NO. 81 13: JAMMED SOURCE RACK IN A GAMMA IRRADIATOR 

Purpose: 

This information notice provides information about a general potential 
problem area involving product pass systems and the source rack in certain 
types of gamma irradiators used for research and product sterilization. This
information should be brought to the attention of all persons involved in 
the administration and operational aspects of your irradiator facility. 

Description of Event: 

During manual shutdown of a gamma sterilizing irradiator, the source rack 
failed to return to the shielded position in the storage pool. Subsequent 
review of the event determined that the source rack was prevented from 
returning to the shielded position by product carrier boxes that were 
damaged and in disrepair. The product boxes had bent out corner edges and 
flaps that extended into the travel path of the source rack. The source 
remained in the unshielded position for approximately 24 hours. 

Beginning about 10 hours after the jamming of the source rack and continuing
until it was returned to the shielded position, several fires occurred in 
the product and product boxes. The fires were extinguished by the sprinkler 
system. After approximately 24 hours, the source rack was successfully 
lowered to the shielded position by a service crew from the manufacturer of 
the irradiator. The jammed source rack defeated emergency shutdown systems. 
Even though there was no damage to the source pencils, there was some damage
to the source pass conveyor that caused several days of down time. 

This incident is significant relative to irradiator safety in that the 
damaged product boxes prevented shutdown of the irradiator. Subsequent fires
also occurred in the combustible product and product boxes as a result of 
prolonged gamma irradiation. 

If your irradiator system uses a product pass system and/or product carrier 
boxes, you should have procedures for inspection and removal of product 
boxes that are damaged or in any other way could interfere with the source 
rack travel. 

No written response to this information notice is required. If you need 
additional information regarding this subject, you should contact the 
Director of the appropriate Regional Office. 

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