Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
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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