Posted by: daniellesabai | 2011/03/30

The Worst Has Happened at Fukushima No. 1 Nuclear Power Plant

Saito Koji

The Worst Has Happened at Fukushima No. 1 Nuclear Power Plant

TEPCO and Government Should Stop Manipulating Information !
Stop All Nuclear Power Plants Immediately !

Emergency declared around the nuclear power plant

At 3:50 p.m., JST, March 11, one hour and four minutes after the massive earthquake, the highest tsunami wave of over 7.3 meter were observed at a tide gauge station of Japan Meteorological Agency at the offshore of Soma, Fukushima Prefecture. Before the tsunami reached the peak level, the wave had already reached the coast of the prefecture and damaged the peripheral facilities of the nuclear power plant.

Let’s examine what happened in chronological order based on the announcement of the government’s disaster headquarters :

3:42 p.m. – Tokyo Electric Power Co. (TEPCO) notified the government of « the loss of all AC power supply » at the 1st, 2nd and 3rd Units, which were then operating, of Fukushima No. 1 nuclear power plant as required by the Nuclear Disaster Special Measures Law.

3:45 p.m. – The tsunami washed away oil tanks supposed to be used as the emergency diesel generator for the plant.

4:36 p.m. – After the emergency core-cooling systems of Unit 1st and 2nd were found to be incapable of injecting cooling water to the units, the government declared « nuclear emergency » and set up its disaster headquarters. The operation started to prevent a worst-case scenario, melting of the reactors, by mobilizing power supply cars and fire pumps, including those of Self Defense Forces (SDF), from nearby area. Air Self Defense Force from Komaki City, Aichi Prefecture, was mobilized to transport three units of special fire pumps from a subsidiary of Toshiba Corporation.

10:00 p.m. – TEPCO and Nuclear and Industrial Safety Agency (NISA) were said to be working on the following hypothetical scenario for the 2nd Unit, which was regarded as the most dangerous : exposure of the core on 22:50 ; fracture of the fuel cladding tube on 23:50 ; melting of the fuel on 24:50 and, two and a half hours later, releasing of radioactive material from the containment vessel (on 4:20 next day). This scenario came true to another unit earlier.

Potential damages, underestimated deliberately

On Sunday night (March 13), the president and the management of TEPCO held a press conference for the first time after the earthquake and said, « the tsunami was significantly beyond the level we had anticipatd. » It may be true that the tsunami may have exceeded the level which proponents of nuclear power plants had assumed. In fact, the level assumed by them deliberately ignored or minimized the effects of undesirable situation. Without pretending that way, they could not continue the operation of the nuclear power plants. The interest of big businesses of the electricity industry penetrated bureaucracy and academic establishment, which contributed to worsening of the damage.

On the same day, Earthquake Research Committee, which is working with the Ministry of Education, diclosed its view on the earthquake, explaining that the earthquake involved four of seven pseismic epicenters in the region at one time and the fault rupture was 500 km long and 200 km wide with the slip distance of up to 2 m. The scale of earthquake magnitude was M9.0 was the fourth in recorded history of the world, and close to the M9.1 observed at the offshore of Sumatra Island in December 2004. According to the Geospatial Information Authority of Japan (GSI), along the coast of the area, subsidence of 75 cm took place almost simultaneously with the earthquake, which further extended the scope of tsunami. As the result, at the bay along Sanriku Ria Coast, the tsunami was well over 10 meter high.

But was this really unforeseen ?

i) At the offshore of Miyagi prefecture, which has been regarded as one of the seven seismic epicenters in the region, the average interval of earthquake is 37 years and the last one was in June 1978. Well over thirty years has already passed since the 1978 earthquake. The government’s official position was that the probability of the occurrence of another earthquake in this area within thirty years was 99 percent.

ii) In the coastal area from Sanriku Coast to Boso Peninsula, it has been estimated that earthquakes of M 8.2 level followed by big tsunamis occur once in every 133 years in the average. The govoernment had assumed that the probability of the occurrence of another such earthquake within thirty years would be 20 percent.

iii) Several researchers pointed out the similarity between the earthquake and tsunami which hit this area in 869 and the 2011 case, based on historical data. In the 869 case, which hit Taga Castle area, around 1000 people drowned to death. This should have been considered in the risk assessments.

Hadn’t the promoting forces of nuclear power plants suppressed these warnings ? Verification is needed.

The situation worsened day by day

A nuclear power plant is said to be protected by fivefold barriers which prevent it from leaking radioactivity into the environment under any emergency. The first barrier is the fuel pellets : uranium is baked and hardened to pellets so that uranium powder may not be released to the atomosphere. The second is the tube sheaths of zirconium : fuel pellets are contained in these sheaths. The third is the reactor pressure vessel, the fourth is the containment vessel and the fifth is the building, which is visible from the outside. In addition to these physical barriers, « social » barriers such as the site boundary, the in-house evacuation zone and the evacuation zone are supposed to prevent the exposure in the emergency situation.

At the time of the Chuetsu Offshore Earthquake, which hit Nigata Prefecture in July 2007, the Kashiwazaki Kariwa nuclear power plant was damaged and the operation stopped automatically. The water temperature within the reactor dropped below 100 degree (Centigrade), which deemed to be a non-dangerous level, about 20 hours later. In comparison with that case, the seriousness of the danger at the Fukushima plant was already obvious in the first few days. It would have been 40 years on March 26 this year since the Fukushima No. 1 nuclear power plant was launched. NISA had just approved the extension of the duration period for another 10 years on February 7 this year. The agency also accepted the quake-resistance standard adopted for the plant.

Twenty hours after the earthquake, at which time the water temperature within the reactor should have dropped below 100 degree as had been the case in Kashiwazaki Kariwa, it was found that parts of the nuclear fuel were exposed above the water.

Twenty five hours after the earthquake, there was a curious announcement by TEPCO. It said « in the wake of a large scale inland aftershock, there was a big explosion in some area between Unit 1 and Unit 2 of the power plant, causing white smoke ». TEPCO pretended as if the explosion had been caused by some aftershocks.

It seemed that the explosion led to the reduction of the pressure inside the containment vessel and that it became possible to inject water from outside. Injection of sea water and boric acid, which absorbs neutrons and inhibits fission, began. As sea water contains impurities which degrades the steel, decommissioning of the reactors became unavoidable. No indication of cooling down was seen at the early morning of March 15.

On Monday (March 14), sixty-eight hours after the earthquake, the top of the building at Unit 3 blew in a hydrogen explosion. At Unit 3, MOX fuel containing Plutonium had been used since September 23 of last year, which had been authorized by the Fukushima prefectural government on August 6 that year. Meanwhile, a more serious explosion was observed at Unit 2. At 6 a.m. on Tuesday (March 15), the fourth day after the earthquake, an explosion occurred in the vicinity of the containment vessel and the suppression chamber, which adjusts the pressure in the vessel, and they might be damaged.

Deceptive introduction of « Rotating blackouts »

It is reported that many local residents were exposed to radiation on their way to the evacuation sites. Rescue corps from SDFs were also exposed in their tasks for cooling the reactors. The U.S. Navy, which was deployed off the coast of Sendai, is monitoring the level of radiation independently and keeps away from the area where the level of radioactivity is high.

The fact that radiation is observed in many places indicates that the fivefold barriers have all collapsed already to some extent. The exposure of the nuclear fuel above the water means that the cooling water cannot act on the heat on the surface of fuel. Therefore, it seems certain that, as TEPCO admitted, the fuel has already begun to melt.

Nevertheless, TEPCO and the government maintained that the accident was within the scenario of « level 4 » as stipulated in IAEA’s scale. The danger of « level 5 » events or melting of the core and the pressure vessel, like what happened in Three Mile Island in 1979, were already indicated in various analyses and reports. The danger of « level 7 » events cannot be excluded. « Level 7 » events mean, as was the case in Chernobyl in 1986, a huge amount of radioactive ash accumulated on the core is discharged to the atomosphere, a large tract of land has to be abandoned and a lot of lives are eventually lost because of the exposure to the radiation.

At this moment, while Prime Minister’s Office are speaking about the safety, the fire-fighters and SDF corps are working hard in the deadly situation. Although the government admitted the release of radioactivity, they pretends as if the « social » barriers could minimize the effects to a neglectable level. This kind of imprudence cannot be allowed in the face of the real danger, which always accompanies nuclear power plants.

The government and TEPCO announced the introduction of a « rotating blackout » scheme in Kanto region (Tokyo and the surrounding prefectures) as an emergency measure. The aim is to show up the necessity of the nuclear power plants.

The government under Democratic Party inherited the policy of Liberal Democrats in promoting the construction of nuclear power plants. Many nuclear power plants were built on rural area close to potential seismic epicenters. Local governments and local people have been forced to accept the plans in exchange for economic benefits. The Kan government is promoting nuclear industry as one of the pillars of its economic growth strategy. It is fully cooperating with the industry to export nuclear power plants to other Asian countries. Faced with the catastrophe in Fukushima, they have no other way than resorting to deception and oppression in order to defend the interests of the nuclear industry.

Even the possible Tokai earthquake, which would trigger a disastrous nuclear power plant failure, is supposed to be « M8.4 ». That means nuclear power plants operating in the affected area of Tokai earthquake are only prepared to resist « M8.4 ». Kashiwazaki-Kariwa nuclear power plant was also hit by a strong aftershock, but the operation of the plant is not stopped.

If the government is concerned with safety and security, it should immediately stop all nuclear power plants in the whole country.

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