United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #: 9702270047



                         DEPARTMENT OF THE ARMY

                 UNITED STATES ARMY RESEARCH LABORATORY

                          2800 POWDER MILL ROAD

                      ADELPHI, MARYLAND 20783-1197



REPLY TO

THE ATTENTION OF            February 19, 1997



Risk Management Division



U.S. Nuclear Regulatory Commission

Document Control Desk

Washington, DC  20555



Dear Director:



     This letter is being submitted in accordance with 10 CFR 36.83 to

report a failure of our backup alarm system at our cobalt-60 facility

irradiator, located in building 504 of the address indicated on the

letterhead above.  The irradiator is authorized by license 19-17250-05. 

A telephonic report was made at 1:49 PM on January 21, 1997, to Ms. Betsy

Ulrich of Region I, and another on January 22, 1997, to the Operations

Center.



     On January 20, 1997, at approximately 6:00 PM, our facility

supervisor found, upon visiting the facility, that the back-up alarm

system was activated even though the facility was not being used at the

time, and the cobalt-60 sources were stored safely at the bottom of the

pool.  On January 21, 1997, our chief operator inspected the system and

determined that the semiconductor relay that activates the back-up alarm

had failed.  A replacement relay was therefore ordered.  Use of the

facility for in-air operations was suspended while awaiting arrival of

the new relay.  On February 4, 1997, the new relay arrived, was

installed, and was found to be functioning correctly upon testing.



     The relay that failed is manufactured by Crydom, model D1210S.  The

cause of the relay failure is unknown, but is believed to be due to

normal wear, tear, and fatigue.  In what we believe was an unrelated

event, heat was lost to the mechanical room that services the cobalt-60

facility.  As a result, a water pipe froze and broke in the mechanical

room, and the room was flooded with water until it was noticed and

repaired.  A small amount of moisture made its way into the cable trench

in the cobalt-60 facility control room, but the chief operator does not

believe this was the cause for the failure of the back-up alarm relay. 

It was because of the water line break that the facility supervisor was

visiting the facility on January 20, 1997, to assess any potential impact

on facility function and safety.



     Our license authorizes 60,000 curies of sealed cobalt-60, although

the current inventory is only about 21,000 curies.  No exposure was

involved with this equipment failure or the corrective actions taken.



                 ARL - A NATIONAL REINVENTION LABORATORY





                                   -2-



     If you have any further questions, please feel free to contact my

Radiation Protection Officer, Mr. Michael Borisky, at (301) 394-2218.



                                   Sincerely,





                                   O. J. Williams

                                   Colonel, U.S. Army

                                   Chief of Staff



Copies Furnished:



U.S. Army Materiel Command Safety Office (Mr. John Manfre)



U.S. Nuclear Regulatory Commission, Region I, 475 Allendale Road

King of Prussia, Pennsylvania  19406-1415





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