Fukushima Daiichi crisis: international reaction
The UK utility response15 August 2011
In the days after the Japanese earthquake and tsunami in mid-March, the UK’s EDF Energy set up a crisis team and performed some short-term engineering checks of the seven advanced gas-cooled and one PWR stations it operates.
Mark Hartley, head of design authority for EDF’s existing nuclear fleet (which includes its safety case), introduces the company’s early actions to Will Dalrymple.
“First, it is important to emphasise that I myself and most of the people in the industry really feel for the people of Japan. Our thoughts are with them, and it is hard to imagine how difficult are the circumstances under which they have been working for the last few weeks. We must be careful not to forget the human side of things.
“It is worth setting the context as well. First is the context of the earthquake zone. Japan is well-known to be in a highly-active earthquake zone. The UK is not; it is in the middle of a big continental plate, and the nearest edge is in the Aegean [Sea in Greece]. That said, it is important not to be complacent. It is clearly key that we and the international community learn from such an event. As Vincent de Rivaz said [on 17 March; see also box], we have to have humility and leadership. This means that we will listen to others and learn, and have the leadership to do the right thing now and in the future.
“For any operational experience originating from something like this, our immediate response is to check that any new information does not change our view on the safety case to operate our plants. Following that we promptly review a number of wider areas based on what we know now. That includes some of the things that de Rivaz mentioned: checking backup systems or refresher training. It is important to note that this work complements our normal processes. We carry out regular periodic safety reviews that take into account any operational experience or events as well as reviewing the plant and safety case against modern standards. Operational experience is also reviewed as part of normal business and if urgent action is required, it can be taken, which may result in amendments to the safety case, or the changes to the plant in the long term. It is normal business for us to review our safety systems on a regular basis. As a prudent operator, what we are doing now is over and above what we do anyway. So what has happened on our plants?
“Seismic walkdowns have been carried out to confirm that the plant is able to withstand an earthquake. The review covers simple things such as making sure objects that could move are anchored where they need to be, right down to ‘is the backup plant as expected?’ Those checks were carried out, and there were no significant issues identified. As a follow-on, key backup electrical systems have been reviewed. And again, there are no significant issues. That is what we expect, given our normal review process.
“So we can state that there is confidence in the safety case. There is nothing here to challenge the view of that. That was the purpose of the special board meeting of the licensee board. Nonetheless, we will work with [UK head regulator] Mike Weightman to ensure that we continue to assess our plants critically in light of what is learned from Japan. We are not complacent.”
What was included in the fault operation review that de Rivaz mentioned?
“I presented to the main board [on 15 March]. We reviewed the safety case for operations, that everything that should be in place was, and that what we understood of the event then had not challenged our safety case. As the events have gone on, that has remained the case. The events have been reviewed with reference to the periodic safety review, confirming that any issues that could be significant have been closed down satisfactorily. An initial review of all the required backup plant looked at defence-in-depth and involved a safety-case check, to make sure that the stations have got all the things available to ensure safe shut down and cooling. This was confirmed to be the case.”
The problems at Fukushima Daiichi have to do with station black-out (SBO). How do you deal with station black-out?
“We calculate the frequency of the event. A one-in-10,000 year event is a design-basis event, which we, like many others across the world, base our design protection on. We protect against a complete station blackout through diversity. All of our stations have backup generators in multiple forms. It is highly unlikely that there will be a station black-out, because of the backup plant we have. But we have arrangements in place to deal with that eventuality. To give an example of that, Heysham 2 has different types of backup diesel that are segregated and separated. The diesel houses are on the four corners of the site, and each diesel could supply all of the power required. In emergency planning, one asks, “What could happen if we lost everything—where does that take you,” and the answer is that the company can ensure that there are appropriate arrangements in place so that we can respond in the timescales required to cool the plant.
“For a gas-cooled reactor, which are the majority of the reactors in the fleet, then we have a significant period of time to act; much longer than with water reactors. Gas-cooled reactors allow time for a response; they have a low power density and a high thermal mass. The action time (depending on the situation) can be measured in days, which allows us to do things to recover our position. There is an offsite arrangement, including access to equipment to restore power. I can’t be specific about exact timetables or exact equipment used because of the security implications.”
What about Sizewell B?
“As a PWR, it is part of a large family. The approach taken is similar to France and the rest of the world. This is a more recent reactor design, and it has some quite advanced design features, such as a double-skinned containment (which is also included in the EPR design) and numerous backup cooling and electrical systems, which are segregated and separated. It also has steam-driven pumps which have the ability to cool the plant in conditions of a total blackout. So while a faster response is required for it, there is equipment designed in, so that there is plenty of time to restore offsite power.”
Please would you talk about the refresher training?
“Our initial review was to check if there are areas where increased operator training would be a benefit in light of the Fukushima event. We are also considering the benefit of bringing planned refresher training forward. One area we have brought forward in training sooner than planned is how to respond to beyond-design basis accidents. The key message coming out of the event in Japan so far is the need to consider how recovery from a beyond-design basis event is best achieved if significant infrastructure in the country has been lost. What view can you take on an emergency when the infrastructure of the country may be damaged? That is not an issue that is unique to EDF, it is a lesson worldwide.”
Isn’t this also about the issue of where to draw the line between design-basis and beyond design-basis?
“There is a well-trodden path about how to draw that line. When you look at beyond-DBA, there is an extra dimension, beyond engineered lines of protection, about what arrangements in the emergency scheme give us confidence that equipment could be brought into our sites in the required time.
“In this country, our emergency systems mirror national emergency arrangements. So we have a direct connection to the national infrastructure to resolve any issue, whether it is the military to airlift a component, those sort of arrangements can be made. As an emergency controller, that is something I have thought about. A key element is to review the emergency plan to consider what additional equipment may be required and how we would get it to the right place.
“To illustrate: if I wanted extra protection, I might buy packaged diesels to connect up to the plant—this is the sort of thing that we already have. There is an argument for holding them on site, but then the hazard that affects the site could affect those as well. If I hold them offsite, how quickly can they get there and be connected? What arrangements can be put in place; do we expect them to transported by road? But the bridges might be down. Would they need to be airlifted?
How do you justify the expense of beyond-DBA mitigation?
“There are a whole range of factors. In the UK, it comes down to demonstrating that the risk is ‘as low as reasonably practicable’. That means balancing the risk to the public in terms of radiation release against the practicability of mitigating the risk. There is not a straightforward equation for that. It often depends more on what is practicable in engineering terms than it does on cost. You might say, “Okay, I am worried about flooding, I will put all my backup diesel generators high up in the air,” but then you might be worried about its susceptibility to another hazard (such as an airplane strike) and need to think more broadly about it.
“I am confident that our normal processes will deal with this. In case of less severe events, we have a procedure of reviewing operational experience worldwide, and have systems of reacting to such experience on our sites, in collaboration with WANO and INPO, to make sure we are taking a holistic approach.
“What we have chosen to do within EDF Energy is for a short period to enact a shadow version of our emergency arrangements, essentially to look at the information coming in and react to it if needed. Through this team we can provide help to the Japanese if requested. This team has now moved into a project structure that is controlling any short-term actions, and will then also take on anything long-term. This system is just how we have chosen to mobilise people (inside the company). We have used a version of the emergency arrangements to mobilise people centrally to take project control of the event.
It is an expedient way to keep control of information. About a dozen people have been involved; that is not looking at the plant, but just a team of people sharing relevant information. We have had daily calls within the company. Two special meetings of the licensee board have been held to formally review information. We practice our emergency arrangements regularly, and they are a well-trodden path when we need to act quickly.”
How are your actions linking up with France?
“We have a lot of contact with our French colleagues. They have a team organised in much the same way as ours, and the communications are linked up. We are now looking across the whole group to respond in a consistent manner. The EDF approach across the board is similar, although there are subtle differences in detail.”
Where would you expect to be six months from now?
“We will not prejudge the Mike Weightman report [on the lessons of Fukushima Daiichi for the UK industry. An interim version is due in May, with a final version in September]. The key thing is that we have robust arrangements, and we are taking in and reviewing information as it becomes available, and thinking seriously about what it means to us. Any actions that come out of the Japan event will be taken forward, remembering that we need to be working closely with the Nuclear Installations Inspectorate.”
|Leading from the top|
EDF Energy CEO Vincent de Rivaz introduced EDF Energyâ€™s actions in a speech at the UKâ€™s Nuclear Development Forum on 17 March. He said: