Information Notice No. 89-82: Recent Safety-Related Incidents at Large Irradiators

                                UNITED STATES
                           WASHINGTON, D.C. 20555

                              December 7, 1989

Information Notice No. 89-82:  RECENT SAFETY-RELATED INCIDENTS AT 
                                   LARGE IRRADIATORS 


All U.S. Nuclear Regulatory Commission (NRC) licensees authorized to possess 
and use sealed sources at large irradiators. 


This notice is intended to inform recipients of recent safety-related 
incidents at large irradiators and emphasizes the need for proper management 
actions and attention to preventive maintenance programs.  This notice also 
serves to remind licensees of other safety-related incidents at irradiators 
covered in Information Notice 87-29.  It is expected that licensees will 
review this information, distribute the notice to responsible radiation 
safety staff, and consider actions, if appropriate, to ensure both proper 
preventive maintenance programs and proper management actions to preclude 
similar situations from occurring at their facilities.  However, suggestions 
contained in this notice do not constitute any new NRC requirements, and no 
written response is required. 

Description of Circumstances: 

A description of each of the following events is provided in Attachment 1.  
In summary, these events included: 

x    Deliberate bypass of the radiation monitor interlock system and another 
     safety system designed to protect individuals from radiation-produced 
     noxious gases.

x    Significant contamination of pool water remaining unnoticed, which 
     could have been detected sooner, had the pool water been continuously 
     circulated and monitored through the demineralizer. 

x    An uncontrolled descent of a shipping cask into an irradiator pool, due 
     to brake malfunction on a lifting crane.

x    Leaks in the irradiator pool caused by localized caustic stress 
     corrosion in pool liner welds. 


                                                       IN 89-82 
                                                       December 7, 1989 
                                                       Page 2 of 3 


Licensees are reminded of the importance of ensuring the safe performance of 
licensed activities in accordance with NRC regulations and the requirements 
of their licenses.  Irradiators with high activity sealed sources are 
capable of delivering life-threatening exposures in a short period of time.  
Therefore, compliance with regulatory requirements and proper equipment 
maintenance is critical to safe operation. 

Event Nos. 1, 2 and 3 on Attachment 1 illustrate a failure by management to 
assure that proper safety and maintenance procedures are followed.  In June 
1987, NRC brought to the attention of irradiator licensees other incidents 
that were caused by similar management practices.  (See Attachment 2).  
Event No. 4 on Attachment 1 is included in this notice to remind licensees 
of the possibility of pool leakage, the need to investigate the causes of 
such occurrences, and their responsibility to take appropriate corrective 

In view of the current and past incidents at irradiator facilities, it is 
strongly recommended that supervisory personnel be reminded of their 
responsibilities to evaluate potential safety hazards and assure safe 
operation at their facilities.  The incidents described in Attachment 1 
demonstrate the importance of: 

1.   Not bypassing interlock systems and other safety systems.

2.   Adhering to regulatory requirements, license conditions and authorized 
     operating procedures.

3.   Continuously using demineralizers equipped with radiation monitors, or 
     alternatively, frequently monitoring pool water conductivity and 
     radioactivity concentration.

4.   Properly maintaining equipment used with or incident to handling 
     licensed materials. 

5.   Taking appropriate and effective action when operational abnormalities 
     are observed. 

Licensees are reminded that NRC must review and approve operating and 
emergency procedures prior to implementation at irradiator facilities.  
Licensees are also reminded that operating procedures approved by NRC during 
the licensing process are incorporated by reference into the license as 
requirements.  Such operating procedures cannot be modified without prior 
approval.  If you have developed alternate procedures that could be used 
temporarily to keep your facility operating during maintenance intervals, 
you must file an amendment with NRC regional offices, for review and 
approval, before such procedures can be used at your facility. 

                                                       IN 89-82 
                                                       December 7, 1989 
                                                       Page 3 of 3 

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:  Tony Huffert, NMSS
                    (301) 492-0529

1.  Events That Occurred at Large Irradiator Facilities
2.  Information Notice No. 87-29
3.  List of Recently Issued NMSS Information Notices
4.  List of Recently Issued NRC Information Notices


Event No. 1 occurred at Isomedix, Inc. (Docket Nos. 030-08985 and 030-19752) 
  at their Parsippany, NJ and Northboro, MA plants in August 1987. 

Event No. 2 occurred at Radiation Sterilizers, Inc. (State of GA licensee) 
  at the Decatur, GA plant in June 1988.

Event No. 3 occurred at Radiation Sterilizers, Inc. (State of GA licensee) 
  at the Decatur, GA plant in July 1989. 

Event No. 4 occurred at the Defense Nuclear Agency's Armed Forces 
  Radiobiology Research Institute (Docket No. 030-06931) in Bethesda, MD in 
  April 1989. 

                                                            Attachment 1 
                                                            IN 89-82 
                                                            December 7, 1989
                                                            Page 1 of 2 


1.   A licensee deliberately bypassed the radiation monitor interlock 
     systems and substituted an administrative procedure for the engineered 
     safeguard provided by the radiation monitor interlock.  The substituted 
     cell entry procedure was implemented without NRC review, approval and 
     incorporation in the license.  The alternate procedures did not 
     constitute an entry control device that functioned automatically to 
     prevent inadvertent entry and did not comply with the requirements of 
     10 CFR Subsection 20.203(c)(6)(i).  In addition, the licensee installed 
     jumper cables to bypass ventilation system interlock which were 
     designed to automatically protect individuals from noxious gases 
     produced as a result of irradiation. 
     Because of the extremely high radiation exposures that could result if 
     interlock are not operational, NRC concluded this incident was a very 
     serious violation of safety requirements.  The licensee was not allowed 
     to operate the irradiator until all safety systems were fully 
     operational.  This violation of NRC requirements, along with other 
     safety-related violations, resulted in NRC proposing a substantial 
     civil penalty. 

2.   Leaking cesium-137 source capsules contaminated pool water at Radiation 
     Sterilizers, Inc.'s (RSI's) Decatur, GA plant and remained undetected 
     for an extended period of time, because the licensee did not use the 
     pool water monitoring system associated with the demineralizer.  The 
     contamination problem was finally discovered when the licensee took 
     discrete samples and performed radiation surveys of the pool water, 
     after activation of the radiation-level monitoring system, which had 
     automatically locked the sources in the safe storage position, due to 
     excessive radiation levels while the sources were in the stored 
     Failure to continuously use the demineralizer/pool-water monitoring 
     system was contrary to the licensing Agency's understanding of the 
     operations.  Had the demineralizer been operated continuously, pool 
     water contamination possibly could have been detected earlier and 
     enabled the licensee to begin mitigating the contamination. 
     The facility has been shut down since June 1988.  The U.S. Department 
     of Energy (DOE), its contractors, and the State of Georgia are managing 
     decontamination efforts at the site, which have been estimated to cost 
     several million dollars so far.  The DOE and RSI are also in the 
     process of removing all the Waste Encapsultion Storage Facility sources 
     from the RSI facilities at Decatur, Georgia and Westerville, Ohio and 
     shipping them to DOE. 


                                                            Attachment 1 
                                                            IN 89-82 
                                                            December 7, 1989
                                                            Page 2 of 2 



     The State of Georgia and DOE are conducting investigations of other 
     aspects and lessons learned as a result of this event.  NRC has been 
     periodically providing information in the NMSS Licensee Newsletter on 
     the status of the DOE investigation into the cause of the source 
     leakage.  Licensees will be sent further information when it becomes 

3.   A contractor providing lifting crane services at a licensed facility 
     was moving a shipping cask from the source storage pool to a mezzanine 
     area, when the cask made an uncontrolled descent of approximately 19 
     feet.  The cask stopped its descent approximately five feet below the 
     surface, only after an operator activated a manual brake.  No personnel 
     were injured and there was no damage to, or contamination of, the 
     licensee's facility or equipment as a result of this event.  However, 
     had the cask not been secured quickly, it could have damaged the 
     radioactive sources in the pool or the pool itself. 
     This incident was a result of improper brake adjustment of the crane 
     hoist.  The crane brake was subsequently repaired and recertified for 
     normal operations in accordance with current Occupational Safety and 
     Health Administration regulations.  Braking system inspection and 
     adjustment, as well as functional load testing, are now established 
     daily procedures before crane operation.

4.   A licensee experienced a loss of pool water for several weeks that was 
     approximately three times higher than expected from evaporative losses.  
     The licensee performed tests to characterize the nature and quantity of 
     the water loss and began daily assays of the pool water to determine 
     compliance with release limits for unrestricted areas.  Suspecting a 
     leak in the irradiator pool, the licensee inspected the stainless steel 
     liner and found localized caustic stress corrosion in many welds. 
     Apparently, welds made during construction of the facility in 1968 were 
     not in accordance with industry standards.  Thus, these faulty welds 
     were subject to caustic stress corrosion which resulted in the recent 
     pool water losses. 

     The facility has been shut down pending completion of repairs. 

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