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1. Dr. Farnan is going to
1) lead the group of companies.
2) dispose of nuclear waste.
3) study radioactivity.
2. In Fukushima, radioactivity leaked through
1) broken pipes.
2) different fractures.
3) interaction with water.
3. After the tsunami struck, the plant
1) had about 8 hours to take action.
2) had no way of pumping the water.
3) disabled backup generators.
4. The main reason for the explosion was the reaction between
1) the fuel and hydrogen.
2) hydrogen and zirconium.
3) hydrogen and oxygen.
5. Even though the nuclear reactor had been shut down, it was still
1) producing electrical power.
2) producing thermal power.
3) being cooled.
6. The plant was unable to restore the energy supply because
1) the tsunami was too high.
2) they had no backup generators.
3) they had no diesels.
7. Dr. Farnan is sure that
1) the Fukushima accident is no worse than the Chernobyl disaster.
2) scientists are unable to evaluate the effects of the Fukushima accident.
3) radioactive contamination decreased in the first two to three weeks of the event.
1 – 1
2 – 3
3 – 1
4 – 3
5 – 2
6 – 1
7 – 2
Chris: To bring us up-to-date with events at the Fukushima Nuclear Power Plant, we’re joined by Dr Ian Farnan from the Department of Earth Sciences at Cambridge University.
Dr. Farnan: Hello, Chris.
Chris: First of all, could you just give us a quick round up on what you work on?
Dr. Farnan: My main research is on the disposal of nuclear waste and in particular I’m going to head up a research consortium funded by the nuclear authority on disposing of spent nuclear fuel. The way that radioactivity leaks from spent nuclear fuel is by its interaction with water. Actually, radioactivity can leak out through broken pipes and other fractures. However, what’s happening in Fukushima is the interaction of water with fresh fuel.
Chris: When the tsunami struck, it knocked out the backup generators, which were there to pump water through the core, and disabled those generators. What then unfolded?
Dr. Farnan: Well, there was a little bit of extra leeway. The plant had some batteries which ran for a little while, for about 8 hours, and then they just ran out. At that point they had no way of pumping the water through the reactor to keep it cool. So the water in the reactor started to boil and eventually, it came out to what’s called a pressure regulator which is below the reactor in a large pit. The dramatic thing that you saw on TV was the problem that there must have been some interaction with the zirconium alloy, which started to get oxidised at high temperatures. The fuel heated up and that produced some hydrogen. So there was a mixture of hydrogen gas in this big pit below the reactor. At some point, the pressure was getting too high and the operators realised that in order to preserve the integrity of the reactor pressure vessel, they needed to vent that pit. When they did that, the hydrogen came out and it obviously encountered some oxygen and there was an explosion, and that’s what you saw on TV.
Chris: But subsequent to that, what was then the threat, the fact that you had no way of cooling a nuclear core that was still producing quite a bit of heat?
Dr. Farnan: Exactly. If you take the Daiichi-1, I think it was about 700-megawatts. So, when the batteries ran out, the reactor was immediately shut down, but even though you stop the critical reaction at that point with the rods in, you still get 5% of the power, and that’s the thermal power. So the thermal power reactor is three times the electrical power. That’s just the efficiency of the generating process. So you have to keep a nuclear reactor cool after it shuts down. Now, what happened at Fuku-shima was that it went into what is called a ‘station blackout,’ and people planned to get the power back in four or five hours. That didn’t happen at Fukushima because the tidal wave was so great that it overwhelmed their diesels and it overwhelmed something called ‘service water 2’. But in any event, they couldn’t get any power to the big pumps.
Chris: Could you compare the Chernobyl disaster and the Fukushima accident?
Dr. Farnan: I have already said that it’s worse than Chernobyl and I’ll stand by that. There was an enormous amount of radiation given out in the first two to three weeks of the event. And add the wind blowing in-land. It could very well have brought the nation of Japan to its knees. I mean, there is so much contamination that it could have cut Japan in half. We are well beyond where any science has ever gone at that point and the accident at the Fukushima Daiichi plant is not a condition that anyone has ever analyzed.