I Want For You To Know What Kind Of Thing A Genpatsu (Nuclear Power Plant) Is - Parts XII ~ XIII

By: Norio Hirai（平井 憲夫）

1996

XII. Startling Mihama Genpatsu Narrow Piping Burst Accident!

People are unaware or just indifferent toward frequent genpatsu accidents that are actually startling and comparable to Three Mile Island and/or Chernobyl. In 1989, the recirculation pumps fell apart at TEPCO’s Fukushima Dai-Ni genpatsu; this accident was also the first of it’s kind in the world.

Then in 1991, the narrow piping burst accident at TEPCO’s Mihama genpatsu discharged large amounts of radioactivity directly into the air and sea.

During the Chernobyl disaster, I really wasn’t so surprised because, as a genpatsu builder, I knew an accident like Chernobyl was bound to happen someday. That’s why I just thought, “So, alas, it happened in Chernobyl and not in Japan…” However, during the accident at Mihama, I was so startled I couldn’t get up from the chair because my legs were shaking.

In this accident the genpatsu was stopped by manually engaging the ECCS (emergency core cooling system); in that sense it was a very serious accident. The ECCS is the last stronghold to protect the safety of the genpatsu. If it doesn’t work, everything is over. So the Mihama accident, where the ECCS was manually engaged, was a major accident. It’s like a bus carrying a hundred million people being driven at the speed of 100 km on the freeway with no brakes and finally stopping by crashing into a cliff.

The radioactive water in the reactor flowed out to sea and the reactor was on the verge of heating up with no water in it. The multiple protection safety valves (that Japan was so proud of…) didn’t work one after another, it was about to become Chernobyl in 0.7 seconds. It was a Saturday; luckily there was a person experienced with the ECCS, because the ECCS wasn’t engaging automatically like it was suppose to, he made a snap decision and manually activated it, so it didn’t become a major accident involving the whole world. The people in Japan, no, the people of the world were really fortunate.

The reason for this accident was because of these metal stabilizers that mount the narrow piping of about 2mm. There are thousands of these narrow pipes and the stabilizers were for anti-vibration measures but were not positioned the way designed, a construction flaw. For nearly 20 years it was not spotted during regulatory inspections, so because of this accident, lax inspections and negligence were revealed. It was also an accident where we realized what genpatsu designers would regards as unbelievable, it was the common onsite construction procedures of “If it doesn’t go in, cut and throw it away. If it doesn’t fit, pull it.”

XIII. Monju’s Major Accident

A major sodium leak accident occurred at Monju operated by PNC (Power Reactor and Nuclear Fuel Development Corporation) in Tsuruga, Fukui Prefecture on December 8th last year (1995). This wasn’t the first accident at Monju, accidents were occurring frequently. I was called 6 times during the construction. It was because the chief, director, shokunins, etc., were my former subordinates; they are also in charge of Monju. So when there are problems, they call me. I’ve already quit the company, but since genpatsu accidents are irreparable, I am unable to ignore the situation so I just go to the site.

One day, there was a phone call that said, “The pipes don’t fit, no matter what we do.” I went and took a look. All the specially made pipes and off-the-shelf pipes were the dimensions as on the drawing, but they didn’t fit. I tried hard to figure out how to get them to fit, but couldn’t understand it for a while. I thought for a night and finally understood. Various companies built Monju, such as: Hitachi, Toshiba, Mitsubishi, and Fuji Electric. The design standards of the companies were different.

When they do the drawings, at Hitachi where I was, 0.5mm was truncated, Toshiba and Mitsubishi 0.5mm was rounded up, and JAEA 0.5mm was truncated. It was only 0.5mm, but when collected from a hundred places, it makes a really big difference. So by the drawings, parts should fit, but do not.

It was not ok this way, so we re-made them. It was connected to the dignity of the nation anyhow, so we spent the money.

So why did it end up like this? It is because each company has their own knowhow, company secrets. They discuss general matters but they don’t discuss detailed matters like the 0.5mm measurements. The temperature sensors are another example and the reason for many of Monju accidents, I have doubts the manufacturers held discussions amongst each other regarding those either.

The same type of temperature sensors were attached to many of the plant pipes, I have never seen such a long sensor of the kind… There should have been someone during construction that knew it was dangerous. However, the thought was “It’s from another company, so just leave it. It’s not our company’s liability.”

Various power companies staff the PNC and various manufacturers make the parts… Obviously, operating a genpatsu in this way, accidents are bound to happen; if no accidents happen, it would be a mystery.

However, even such a serious accident, the government doesn’t say “an accident.” Just like at the Mihama genpatsu accident, they said, “there was an event.” Right after the accident, I was immediately called and went to the Fukui Prefectural Council. There is a big genpatsu with 15 reactors; the person who bid the company to set up the plant was a LDP (Liberal Democratic Party) lawmaker. I always say to people of this kind “When an accident happens, it’s your fault. The ones opposing the plants are not responsible.” These lawmakers gave me a call this time. “This time I am prepared to fight the PNC, tell me what I should do.” I was asked to consult for them.

So what I first said was “This is an accident, an accident. Do not be cheated by the word ‘event’.” In the Prefectural Assembly, the PNC started their explanation, “The event this time…” the lawmaker shouted, “It’s an accident! Accident!” It was shown on TV; that too, if you keep silent, you will be affected with a light word like “event.” Not only the local people, we should not be cheated with such a light word as “event”.

To ordinary people, the words “event” and “accident” are taken in a completely different manner. This country changes “accident” to “event” so the Japanese, in some cases, have no sense of crisis when a genpatsu accident happens.

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