M. A. Leblanc
Canadian Nuclear Safety Commission
November 16, 2001
This document summarises significant developments for the period of
October 2 to October 30, 2001.
Section 2 was added to the Significant Development Report after its publication
of October 30, 2001.
Signed / Signé le
M. A. Leblanc
Secretary of the Commission
Significant Development Report No. 2001-8
1 Power Reactors
1.2 CANDU Feeder Piping Impairment Issues
This information is to update the Commission on the Feeder Piping Aging and Management Strategy. The licensees individually, and through the CANDU Owners Group [COG], have recently made advances in nondestructive inspection technology. In 2000-2001 they have inspected outlet feeder bends at Point Lepreau, Gentilly-2, Pickering Units 1, 4 and 7, Bruce Unit 8 and Darlington Units 1 to 4. Inspections include both verification of wall thinning due to flow-assisted corrosion [FAC] and inspection for cracking at the outlet bends immediately downstream of the feeder coupling to the end-fitting.
1.2.1 Status of the Outlet Bend Cracking
The COG program has examined, by various techniques, a number of artifacts from both the 1997 and 2001 leaks at Point Lepreau. All of the cracks occurred at the same location on the lateral flanks of the bends. Metallurgical examinations show the leaks were from groups of small inner-surface cracks that linked up and propagated through the feeder pipe.
Hydro-Québec and NB Power have enhanced their feeder cabinet leak detection capabilities and can detect small leaks before they grow. CNSC staff is discussing with OPG and Bruce Power the need to upgrade their feeder detection systems.
The COG program has not yet been able to explain why the cracking is occurring and if the cracking behaviour is unique to the Point Lepreau facility or if it is generic to CANDU reactors. The cracking may be related to high residual stresses in cold bent piping. Point Lepreau, Gentilly-2 and Darlington and Pickering B have cold-bent pipes. Pickering A and Bruce A have hot-forged elbows while Bruce B bent pipes were stress-relieved after bending.
As reported to the Commission in CMD 01-M81, three cracked bends were detected at Point Lepreau this Spring. NB Power staff removed and replaced them with new piping. CNSC staff conditionally approved the Point Lepreau restart for a one-year period of operation, ending
April 30, 2002. NB Power was also required to address CNSC staff concerns with the material properties in aging feeders, inspection procedure sensitivity for detecting small cracks, Primary Heat Transport system chemistry mechanisms for both initiation and propagation of cracks, the inspection acceptance criteria, and performance demonstrations of nondestructive examination technicians’ ability to detect cracks.
Subsequent inspections for cracking were carried out at all stations, and no cracks were detected in any of these inspections. More inspections are planned for 2002.
1.2.2 Feeder Piping Thinning
Wall thinning by flow-assisted corrosion has been observed in all CANDU reactors. The licensees have been conducting inspections and studies to investigate this thinning.
The licensees confirmed during the recent feeder conference that wall thinning continues at various rates at each facility. Feeder piping is predicted for each unit to remain above the thickness required by the original design code for the current operating cycle at all facilities. However, if FAC continues at current rates, it may require repair or replacement of feeders in the next few years.
2. Canadian Nuclear Safety Commission (CNSC) Response to Events of September 11, 2001
Following the attacks on the World Trade Center towers and the Pentagon on September 11, 2001, the CNSC security staff instructed all Canadian nuclear power plants and Atomic Energy of Canada Limited (AECL) to go to the enhanced security state. Shortly thereafter, at about 9:30 am EDT, the CNSC activated its emergency organization, and established contact with domestic security agencies, other government departments and the United States Nuclear Regulatory Commission. Staff monitored the situation closely over the next two weeks. The enhanced security measures put into effect by licensees on September 11 remain in place. The President established the CNSC Security Review Project on September 27 to review the security for licenced facilities and activities as well as internal CNSC security.
The CNSC is not aware of any specific, credible threats to nuclear facilities. However, the CNSC considers it prudent to review the security risks at all nuclear facilities and licenced activities, and to take steps to bolster security where appropriate. The CNSC is approaching this task on an urgent but orderly basis using a risk based approach. Staff initially focussed on those facilities with the greatest risk in the first phase of its review, then moved to review security at less risky facilities and is now beginning its review the security measures of security of the medical and industrial uses of radioisotopes as well as other licenced activities such as transportation.
Phase I: Security at nuclear power plants and Chalk River
The CNSC’s initial priority was to implement, as soon as possible, new security measures at nuclear power plants and the AECL Laboratory at Chalk River. On October 18, the Commission held an in camera meeting to discuss Order 01-1, issued under section 47 of the Nuclear Safety and Control Act. The order requires licensees to carry out a number of measures covering items such as:
-armed presence on-site with improved equipment;
-enhanced security screening of employees and contractors;
-protection against forced vehicle penetration of the secure area;
-improved physical identification checks of personnel; and,
-searching of personnel and vehicles.
The CNSC is satisfied that the recommended ordered requirements are reasonable and practicable. The CNSC’s objective with this order was to achieve a uniform reduction in risk. Some licensees were already in compliance with some of the requirements when the order was issued.
On October 19, the President of the Commission met with the senior executives of Ontario Power Generation, Bruce Power, New Brunswick Power, Hydro-Quebec and AECL to deliver the order, to make the CNSC’s expectations clear, and address questions. It was also made clear to licensees that the Order was the Commission’s first response to the events of September 11; some security-related initiatives, such as hardening vital areas, longer term provisions for armed security personnel, and air and marine exclusion zones are not amenable to orders. Other measures can be expected to follow once these issues have been addressed. Licensees were also reminded, at the October 19 meeting, of their obligations under section 21 to 23 of the General Nuclear Safety Regulations to safeguard the prescribed content of the Order. CNSC staff provided licensees and other stakeholders with a Backgrounder on the CNSC’s security initiative and some Frequently Asked Questions, in order to assist the them in addressing questions on the CNSC initiative from citizens, staff and the media in their communities.
The CNSC is also reviewing the capability of Canadian nuclear power plants to withstand a terrorist strike. This robustness study will include the impact of a modern large-body commercial aircraft fully loaded with fuel, and the resulting fire as well as other threats. CNSC staff is conferring with colleagues at the United States Nuclear Regulatory Commission and at the U.K. Nuclear Installation Inspectorate. Any decisions with respect to “hardening” nuclear power plants to withstand terrorist attacks such as those of September 11 will be taken after a review of plant vulnerabilities. Given the variations in design at Canadian nuclear stations, measures to harden these facilities may need to be tailored for each site.
Phase II: Security at other nuclear facilities
Phase II of the Security Review Project addresses the security requirements at other Class IA facilities, Class 1B facilities, and uranium mines and mills. CNSC staff assigned these facilities into one of three risk categories, based on the potential vulnerability of the facility to theft and sabotage by either internal or external agents, or a combination of both, and the potential consequences. Licensees were advised in writing, on November 2, of the actions proposed by CNSC staff and their comments were solicited.
Following disposition of the licensees comments, the Director General of the Directorate of Fuel Cycle and Materials Regulation will issue an order, under paragraph 37(2)(f) of the Nuclear Safety and Control Act, to the licensees of those facilities that the CNSC requires take immediate or fast action to enhance security (Group 1). The order will address issues similar to the October 18 order to nuclear power plant licensees and AECL. The licensees being subject to an order in Phase II will also sent a Request under sub-section 12(2) of the General Nuclear Safety and Control Regulations to perform a vulnerability assessment (threat-risk assessment). It will be emphasized to licensees that the Orders and Requests that other there may be other actions in the future.
Those Phase II licensees operating nuclear facilities with lower security risks but nonetheless requiring gradual or longer term action to enhance security (Group 2) will be issued a request under sub-section 12(2) of the General Nuclear Safety and Control Regulations on specific security areas and the performance of a vulnerability assessment. Finally, those licensees with facilities with no security concerns will be sent a letter recommending the consideration of enhanced security measures.
As with Phase I, licensees will be reminded of their obligation under sections 21 to 23 of the General Nuclear Safety and Control Regulations to protect the details of the Designated Officer Order, and provided with a communication information including a Backgrounder and Frequently Asked Questions for their use in answering questions from the public, their staff and the press on the CNSC’s initiative.
Phase III: Review of security requirements for remaining licensees
Staff has recently started scoping its review of security at the CNSC’s remaining licensees, numbering approximately 4000. This group includes Class II nuclear facilities, licensees using radioisotopes and radioisotope-containing devices for medical and industrial purposes; companies licensed to transport nuclear substances; dosimetry services, etc. As before, CNSC staff will take a risk-based approach to the review. Given the low risk associated with these activities, the CNSC’s initial approach to these licensee will be encourage the licensee to review their security provisions and take practical measures to improve security.
It is expected that Phase III will begin the week of November 19.
CNSC staff will update Members of the Commission on the progress of the Nuclear Security Project at the Commission’s December 13, 2001, meeting.