Frank Yee

Chief Nuclear Engineer

  

What was your reaction to the natural disaster in Japan on March 11 and the subsequent accident at Fukushima?

Simply put, the first videos of the tsunami rolling over the coastal regions were shocking. It was difficult to comprehend the scale and magnitude of the destruction and loss of life.

The subsequent accident at Fukushima raised many questions in our minds. Was this preventable? As designers, we design for these types of events, so what was missed? What can we learn from this so that it does not happen again?

Has your company been involved in the recovery operations at Fukushima?

Candu Energy Inc. has not been directly involved in the recovery operations at Fukushima. In response to queries from the IAEA however, we did identify individuals with technical expertise who could assist.

What actions has Candu carried out in response to Fukushima?

Candu has carried out the following activities:

• Immediately set up an internal task team to review our current nuclear power plant (NPP) design, to determine whether there were any vulnerabilities in our design, and to take steps for any necessary enhancements.
• Participated as an active member of the Canadian Industry Integration Team (CIIT), composed of all the Canadian utilities, AECL (Chalks River Laboratories) and the CANDU Owners Group. Several international members, including KHNP, NPCIL and TQNPC also participated in the CIIT meetings, as well as WANO. Topical meetings were held between Candu and the CIIT to reach alignment on technical issues relevant to severe accident management and progression. This active participation and integration effort has resulted in a well-aligned response across the industry, including the NPPs supported by Candu.
• Provided technical support to Cernavoda 1 and 2 NPPs, to address the requirements of the European Commission "Stress Tests"
• Attended special meetings organized by the IAEA to discuss with experts the lessons learned and what actions must be collectively taken
• Held focus meetings with the Canadian Nuclear Safety Commission (CNSC), our Nuclear regulator, on their expectations as an outcome of Fukushima
• Continued to develop our plant designs to address severe accidents

The Task Team continues to follow any new information that comes out of Fukushima.

What does the nuclear industry as a whole need to do in response to Fukushima?

The nuclear industry needs to fully understand the lessons learned from Fukushima. This is on-going, and there has been considerable work and sharing of information at organizations such as IAEA, WANO, INPO and CANDU Owners Group, and with the national regulators such as the CNSC in Canada. All the stakeholders must make a concerted effort. The nuclear industry needs to show that nuclear energy is safe and will continue to provide a reliable and cost-effective source of power.

What has and can be done at existing nuclear plants to ensure their safety in response to learning from Fukushima?

The existing NPPs have done assessments in response to WANO, INPO and regulatory requirements. In addition they have done their own assessments for vulnerabilities, especially for beyond-design-basis natural hazards through extensive walkdowns and analyses to determine whether there are any "cliff edges" in which there are low margins of safety. Some NPPs have made design improvements to address any potential vulnerabilities to beyond-design-basis natural phenomena. In addition, NPPs are making provisions to bring in additional portable sources of water and portable power supplies to ensure that there is adequate cooling for the reactor. Enhancements have been added such as passive autocatalytic recombiners and a containment filtered air discharge system to prevent overpressure of containment. The utilities have also looked at improved emergency response procedures in place, followed up by practice drills.

What features do new reactor designs offer to address the issues faced at Fukushima?

New reactors designs have redundancy and passive design features to ensure the ability to contain, control and cool the reactor, even in the event of a severe natural event. Designs that have passive heat sinks, large inventories of water to provide more time for operator action, additional systems and components will be included specifically to address severe accidents. The focus will be to ensure that the core does not get damaged. But even in that event, the new designs will have provisions to ensure that corium will be cooled and will not be released outside containment.

Has Fukushima changed your opinion of nuclear power?  

As designers of CANDU NPPs, we have always developed a safe design with defence in depth. Even though the powerful earthquake and resulting tsunami was a catastrophic event at Fukushima, we believe that we will learn from this event and collectively we will make nuclear power even safer.

Although the events at Fukushima have not changed our opinion of the value of nuclear power, and its significant benefit to society, they have reinforced for us the critical role that we, as designers, have in ensuring that our reactor designs are robust, and in providing the operators of those plants with the flexibility to respond to events that have not been envisioned in the original design.

What do you now see as the future for nuclear power?

We have learned and will continue to learn from the events at Fukushima. We see nuclear power remaining an important part of the energy mix for the world