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Problems with the Emergency Response to the Fukushima Accident (Part 1)

Published on Nov.19 ,2012 : The Denki shinbun(The Electric Daily News)
Dr. Michio Ishikawa
Chief Adviser(Former President & CEO of JANTI

This isn't something I want to talk about but unfortunately it's necessary if we are to discuss everything that went wrong during the Fukushima Daiichi accident. It is however difficult to discern exactly where the problems lie. One of the reasons for this is because the workers who were at the scene and suffered through the ordeal will not discuss what happened.

They are keeping their mouths shut because of potential liability issues that could arise if what they say differs from the reports of the government or the Diet's accident investigation committees. This aspect of Japanese society is one reason why progress into ascertaining the causes of accidents is not made very often.

Additionally, the accident investigation committees did not invite experts in the field of nuclear power. That's why the investigation has not gotten to the core of the matter.

It is in this manner that the pressing issues, including pointing out problems with the emergency response, are not sufficiently examined and are rather relegated to our emotional faculties through vulgar discussions on TV. There is no point making a lawyer perform open heart surgery.

And, if they won't talk, then all we can do is make inferences based on our experience up until this point. I know I don't have all the information but it's a lot better than those vulgar discussions.

Let's review what happened at the time of the accident. All power was wiped out by the earthquake and tsunami. A day later Unit 1 melted down and exploded, two days after that Unit 3 exploded, and one day after that Unit 4 exploded. Around the same time, the Unit 2 reactor containment vessel was damaged and radiation levels around the power station rose suddenly one hundred times. That's what happened.

The evacuation troubles around that time and the mid-air water injection into the fuel pools are off the subject so I will exclude them.

One of the problems has to do with misidentification of operation of isolation condensers (ICs). This mistake is what led to the meltdown and explosion of Unit 1, the damage to the power cables that so much energy was put into laying, and similar incidents at Units 2 to 4. I consider this to be one reason why response was delayed and the disaster escalated as much as it did.

ICs are equipment that cools the core using the natural circulation of steam and requires no electricity to operate. ICs activated automatically when power was lost after the earthquake. But, the reactor was cooled too much, and it was decided to shut down the ICs and operate one of them by manually opening and closing the isolation valve. Unfortunately, the valve had been closed just before the tsunami arrived. Since power was lost due to the tsunami, the valve could not be opened, which resulted in the loss of reactor cooling functions.

However, TEPCO's top-level engineers at the site and head office all assumed, or rather took it for granted, that the isolation valve was open and that reactor cooling was continuing. This is the launching point of the operation misidentification problem and the accident that followed.

Having lost cooling function the core started to get hotter, naturally. The hot cladding reacted with water to create hydrogen and this reaction heat melted the core.

The only thing that could have corrected this mass misdiagnosis was accurate information from the field. After the tsunami had partially subsided, the shift supervisor requested of site headquarters that steam discharge be visually confirmed in order to confirm that ICs were operating. At around 5pm, he received word that “steam was being discharged” and determined that the ICs were working.

At around the same time, the shift supervisor sent shift personnel to the reactor building to check the water level of the ICs. This was to double-check that the ICs were operating. However, operators turned back at the entrance to the building because of higher-than-normal radiation levels. This is a mystery to me.

At around 6pm, DC power was temporarily restored. At this time, the shift supervisor opened the isolation valve, leaving the ICs on and conveyed this fact to headquarters. However, not a lot of steam was released and the discharge immediately stopped so he once again closed the valve. But, this operation was not conveyed to headquarters. This caused a clear divergence between what was happening in the field and the information that upper management had ascertained.

I'm sure this was because of the hectic scene in the field with the blackouts and continuing aftershocks. But, cooling the reactor was of the highest priority at that time. I can't understand why this fact wasn't reported.

If these two things had been done, they would have realized that cooling had been interrupted and been able to easily implement corrective measures. At this point in time, the core had not yet melted. It's regrettable that this opportunity was missed.

When the IAEA inspectors visited the site immediately after the accident, they praised the workers in the field saying that they devoted themselves to doing the best they could. I agree. While they did their best, mistakes and mysteries also occurred. But, I am sure there must be good reasons why these mistakes and mysteries were able to occur.

We are all human and perfection in the face of crisis cannot be expected. However, publicly releasing the reasons and background behind these mistakes and mysteries is the key to solving bigger issues and will aid in making better improvements in the future. I would like to see them brought to light.

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