Atomic Energy of Canada Ltd. is just about to release the following update on the status of the National Research Universal reactor at Chalk River, Ont.. My annotation is in bold …
Atomic Energy of Canada Limited (AECL) provides the following update of activities related to the unplanned shutdown of NRU at Chalk River Laboratories:
· The remaining Moly-99 available for isotope supply has now been removed from the NRU reactor and will be processed today.
· As reported on May 18th, the location of the heavy water leak has been identified at the base of the reactor vessel in a location where there is corrosion on the outside wall.
· The heavy water leak rate remains stable at approximately 5 kg/hr. Options to reduce the leak rate while inspections are ongoing are being considered.
· Due to high airflow in the area, a small portion of the leakage evaporates and results in a monitored tritium release through the NRU ventilation system. Although the airborne release is well below regulatory limits, the release has reached action levels for tritium. [I have asked AECL to explain what it means to have reached these “action levels” and what actions are triggered when this level is reached. I'll post any update here when I receive it.]
· Visual inspections using remote imaging devices are ongoing and will provide AECL with a better understanding of the nature of the leak and repair options.
· An internal reactor vessel inspection using remote imaging was carried out at the leak location. No abnormalities were visible.
· Remote imaging inspection of the external wall of the reactor is ongoing.
· Ultrasonic investigation of the interior vessel wall is set to begin this weekend.
AECL anticipates that the NRU reactor will remain out of service for more than one month. However, the visual inspection process, once completed, will provide a more accurate return to service timeframe.
AECL confirms that there is no threat to workers, the public, the environment or nuclear safety related to this event. AECL will continue to provide updates to the CNSC and stakeholders when new information becomes available.