Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
WASHINGTON, D.C. 20555
December 7, 1989
Information Notice No. 89-82: RECENT SAFETY-RELATED INCIDENTS AT
LARGE IRRADIATORS
Addressees:
All U.S. Nuclear Regulatory Commission (NRC) licensees authorized to possess
and use sealed sources at large irradiators.
Purpose:
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.
8911300050
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IN 89-82
December 7, 1989
Page 2 of 3
Discussion:
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
action.
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.
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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
Attachments:
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
RECORD NOTE:
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.
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Attachment 1
IN 89-82
December 7, 1989
Page 1 of 2
EVENTS THAT OCCURRED AT LARGE IRRADIATOR FACILITIES
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
position.
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.
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Attachment 1
IN 89-82
December 7, 1989
Page 2 of 2
EVENTS THAT OCCURRED AT LARGE IRRADIATOR FACILITIES
(continued)
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
available.
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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