Canadian Nuclear Safety Commission

Canadian Nuclear Safety Commission

December 10, 2007 18:11 ET

Canadian Nuclear Safety Commission Ready to Evaluate AECL Safety Case

OTTAWA, ONTARIO--(Marketwire - Dec. 10, 2007) - The Canadian Nuclear Safety Commission (CNSC) is a quasi-judicial independent regulator of nuclear energy and materials, whose mandate is to protect safety, health, security and the environment, and to respect Canada's international commitments on the peaceful use of nuclear energy.

The President of the Canadian Nuclear Safety Commission is today in receipt of a letter from Ministers Clement and Lunn regarding the extended outage of the National Research Universal (NRU) reactor operated by Atomic Energy of Canada Limited (AECL) in Chalk River. The CNSC is reviewing the contents of the letter.

The CNSC understands the seriousness of the situation and the importance of the beneficial use of radioisotopes in nuclear medicine. The CNSC shares the concerns of all Canadians that this issue needs to be resolved as quickly as possible.

To this end, the CNSC is working closely with hospitals and assisted them by issuing licence amendments to those requiring alternate supplies, where necessary.

As well, CNSC staff has been working on a 24/7 basis to ensure they are immediately able to respond to AECL submissions on the NRU reactor safety case, once it is ready.

When restarting operations at the NRU reactor facility, it is the CNSC's responsibility to verify that AECL meets all regulated safety requirements prior to resuming operations.

BACKGROUNDER

Safety Upgrades: Atomic Energy of Canada Limited's National Research Universal Nuclear Reactor

December 10, 2007

The Canadian Nuclear Safety Commission (CNSC) is a quasi-judicial independent regulator of nuclear energy and materials, whose mandate is to protect safety, health, security and the environment, and to respect Canada's international commitments on the peaceful use of nuclear energy.

The CNSC has issued a licence to Atomic Energy of Canada Limited (AECL) to operate the National Research Universal (NRU) nuclear reactor at Chalk River.

AECL's licence was renewed by the Commission Tribunal in August 2006 in order to operate an upgraded NRU reactor that includes improved safety standards. This licence renewal was issued after AECL provided written confirmation that all required safety system upgrades were met by December 31, 2005.

The upgrades were designed to improve the safety of the reactor by providing systems aimed at preventing accidents or, in the event of an accident, mitigating its consequences. The focus of the upgrades is on the critical safety functions needed by a nuclear reactor, that is: the ability to be shut down and to remain shut down; the ability to cool the nuclear fuel and to maintain cooling over the long term; and, to confine any fission products that could be released during an accident.

These safety upgrades include the following:

- Second Trip System (STS) - to provide a second, independent trip system separate from the existing trip and control system;

- Qualified Emergency Response Centre (QUERC) - to provide, in the event of control room unavailability, an alternate, hazards-qualified location for the initiation and monitoring of all special safety systems;

- Liquid Confinement/Vented Confinement (LCVC) - to provide a defined boundary around the reactor and the primary coolant system to confine liquid and gaseous releases under accident conditions;

- Main Pump Flood Protection (MPFP) - to protect the main heavy water pumps from flooding due to major secondary coolant leaks;

- New Emergency Core Cooling (NECC) - to provide seismically-qualified, closed-circuit, long-term cooling of the reactor core after a loss of coolant accident (LOCA);

- Qualified Emergency Water Supply (QEWS) - to provide a back-up source of secondary cooling in the event of a loss of the primary heat-sink; and

- Emergency Power Supply (EPS) - to provide dedicated, seismically-qualified emergency back-up AC and DC power to the upgrades systems.

Each upgrade has a specific purpose; however, it is the integrated operation of all the upgrades that allows the critical safety functions to be delivered. In particular, the emergency power system (EPS) delivers emergency back-up power to all the upgrades systems such that each system can perform its desired function. Of specific note is the unique need for the NRU reactor to have forced (i.e., pumped) cooling at all times (even in non-accident conditions) as opposed to other reactor systems that can be cooled by thermo-siphoning if their cooling pumps become unavailable. Thus, the uninterrupted delivery of power to the motor starters of Main Heavy Water Pumps P-104 and P-105, as provided by the EPS, is essential for the safe operation of the NRU reactor.

On November 19, 2007, during a safety inspection, CNSC staff discovered that significant safety upgrades to the NRU reactor facility had not been carried out by AECL. This is in violation of the NRU operating licence conditions.

The non-compliance revolves around the lack of connection of two heavy water pumps to an emergency power supply in order to avoid a fuel failure resulting in potential radioactive releases into the environment.

Upon discovery of the non-compliance, AECL announced its decision to voluntarily extend the shutdown of the NRU reactor to connect the two pumps in order to be in compliance with the Nuclear Safety and Control Act, regulations and licence conditions.

As indicated by AECL during a Commission Tribunal meeting on December 6, 2007, CNSC staff and AECL agreed that this is a serious safety issue.

CNSC staff has been working on a 24/7 basis to ensure they are able to respond immediately to AECL submissions related to these safety issues in order to ensure the upgrade is completed and the NRU can operate safely. The Commission is ready to respond to any requests for resumption of operations to be made by AECL. If this request modifies the approved safety case, it will be heard by the Commission Tribunal on an expedited basis.

In order for operations to resume, the CNSC must be satisfied that AECL has met all of its regulatory requirements and licence conditions, and that the reactor can operate safely.

Contact Information

  • Canadian Nuclear Safety Commission
    Aurele Gervais
    Media and Community Relations
    613-996-6860
    1-800-668-5284