The following information was received via E-mail:
The Agency [Illinois Emergency Management Agency] was contacted on 12/1/20 by Sterigenics U.S., LLC to advise that one of their pool irradiator source racks at the Schaumburg location had become stuck in the unshielded position on 11/30/20. The source rack, containing approximately 1.3 MCi of Co-60, was successfully returned to the shielded position and no exposures to personnel or the public resulted. All safety interlocks functioned as designed. This event did not result in any compromises to source security or to any safety or security systems. There is no indication of intentional misuse, theft or diversion at this time.
On 12/1/2020, the Agency was contacted by the Radiation Safety Officer for Sterigenics U.S., LLC, to advise that in the middle of performing scheduled routine safety checks on 11/30/2020, authorized engineers reported that the east source rack failed to return to the shielded position as designed upon completion of a check. The west source rack lowered as designed without incident. Sources contained in the east source rack remained unshielded from approximately 1400 CST until 1648 CST. The event was immediately reported to the Radiation Safety Officer by the two authorized engineers performing the safety checks that day. The Radiation Safety Officer immediately responded to the site to assist in assessment and formulation of an action plan. After consultation with the Corporate Radiation Safety Officer, the Radiation Safety Officer and staff engineers were able to use a hand winch to successfully lower the rack of sources into the shielded position within the pool. Safety and security systems remain operational and functioned as designed throughout the source lowering process. There is no immediate hazard to workers or members of the public as a result of this incident.
This morning [12/1/2020], source modules were removed without incident from the east source rack and are currently shielded and in safe storage at the bottom of the pool. Sterigenics staff are continuing their investigation into the cause for the stuck rack. All interlocks and safety systems were reported as operational. An action plan was formulated in conjunction with Corporate staff to safely and slowly raise the empty east rack using a hand winch so that it can be adequately inspected. IEMA staff will follow up later this afternoon for an update.
A reactive inspection by inspectors is planned for later this week.
Illinois Reference Number: IL200024