AECL provides update on NRU activities
(June 10, 2009)
The following information bulletin is in accordance with Atomic Energy of Canada Limited's (AECL) commitment to enhance its voluntary public disclosure of events related to the Chalk River Laboratories (CRL). (2009 June 10) AECL provides the following status report on the unplanned shutdown of the NRU reactor at its Chalk River Laboratories.
AECL reports that the ongoing process to remove fuel from the NRU reactor is continuing, with 63 of the fuel rods removed as of June 9th. There were approximately 100 rods in the reactor at the time NRU was shut down on May 14th. Of this total, 81 were used for fuel and the remaining used for isotope production and reactor control. Completion of rod removal and the subsequent removal of heavy water from the reactor is projected to be complete by the end of this month.
Measures have been taken to reduce the leak rate with the addition of a solution to temporarily plug the leak site. Results of this action will take time to become evident. The leak rate remains steady at about 4kg/hr. A small portion of the leakage evaporates and results in a monitored airborne tritium release through the NRU reactor ventilation system. While this airborne tritium release remains about 1/1,000 of the regulatory limit, the action level for tritium release to the atmosphere was exceeded this week due to the leak.
Preparation for vessel inspection continues. Special examination equipment to perform this function has been commissioned. A scan on the inside wall of the reactor vessel, at a location adjacent to the leak site, was successfully completed using ultrasonic and eddy current probes. Analysis of the data will require several days to complete.
A team of industry specialists has recently conducted a workshop to review cleaning, inspection and repair technologies for the reactor vessel. AECL will draw on advice provided by this group to determine the best approach to proceed with vessel repairs. Hugh MacDiarmid, President and CEO of AECL stated "We view the production of medical isotopes as part of our core mission, for Canada, and indeed for the world. As such, we have a duty to resume production as soon as it is safe and practical to do so. AECL staff has been working around the clock to complete the investigations and we will draw on all available expertise, both internal and external, so that we apply the best minds to resolve this issue."
Further guidance on a return to service date will be provided once a final decision has been made with respect to the repair technique chosen. AECL continues to communicate closely with CNSC on NRU outage issues, and CNSC safety inspectors at Chalk River are monitoring all NRU work.
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.