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Community Information Bulletins/False Radiological Readings in the Vicinity of Building 150 (NRU)
February 01, 2021

False Radiological Readings in the Vicinity of Building 150 (NRU)

The following information bulletin is in accordance with Canadian Nuclear Laboratories’ (CNL) ongoing commitment to voluntary public disclosure of events related to the Chalk River Laboratories (CRL).

Chalk River, ON – 2021 February 01 – During routine radiological monitoring in the NRU facility building, higher readings than expected were detected. As a result, response measures were implemented by CNL, including additional radiological monitoring in and around the vicinity of Building 150 (NRU).

As an added precaution, measures also included the activation of Chalk River Laboratories’ Emergency Operations Centre or EOC. The EOC oversaw the follow-up radiological assessment.

All readings and samplings in the follow-up monitoring were within normal and expected levels.  It was determined the initial reading was incorrect, the initial elevated reading was confirmed to be a unique response of the sensitive instrument to sunlight during outdoor measurements.

The Canadian Nuclear Safety Commission was notified of this occurrence and the findings related to the follow-up radiological surveys.

Building 150 houses the NRU Reactor. Following the final shutdown of the reactor on March 31, 2018, the NRU Permanent Safe Shutdown Project has safely and systematically closed key facility systems, significantly reduced nuclear hazards in the facility, and has made significant progress in progressing toward a Storage-with-Surveillance (SWS) state.

CNL confirms that there is no threat to workers, the public, the environment or nuclear safety related to this event.



Patrick Quinn
Director, Corporate Communications
CNL, 1-866-886-2325