You are here

Three meltdown at Fukushima; evidence severe damage before tsunami hit reactors

Nuclear Monitor Issue: 
#727
6132
27/05/2011
WISE Amsterdam
Article

Despite the lack of coverage in the international media, the situation at the Fukushima Daiichi nuclear plant in Japan remains, in the words of the International Atomic Energy Agency’s weekly bulletin, “very serious”. Meanwhile, it's becoming more and more clear that, contrary to earlier assumptions, the reactors were damaged by the earthquake rather than the tsunami, although the earthquake "did not exceed design base values significantly".

According to the Tepco 6-9 months scheme to stabilize the Fukushima Daiichi reactors, announced on April 17, the utility expected a sustained drop in radiation levels at the entire plant by July. Following that, a cold shutdown of reactors No. 1, 2 and 3 may take place as early as October, the utility announced then.

But that was predicated on the notion that it could efficiently cool the fuel in several reactors – a harder task if water is leaking out. The company had long suspected that the containment vessels at two other reactors were breached and leaking, but it had hoped the No. 1 reactor was intact and therefore easiest to bring under control.

Tepco was able to better access the reactor on May 12, because workers had recently been able to get close enough to fix a water gauge. It showed that the water level in the reactor was much lower than expected despite the infusion of tons of water. Previous readings had shown the water level to be at 1.6 meters below the top of the fuel rods in the reactor core. As it turned out, these measurements were false. The actual water level was five meters below the top of the fuel rods, leaving them fully exposed.

Tepco has been pumping water into the pressure vessels of reactors 1, 2 and 3 for weeks in a bid to lower temperatures. The low level of water in reactor 1 indicates that the molten fuel might have created a hole in the bottom of the steel pressure vessel. Tepco general manager Junichi Matsumoto told a press conference: “There must be a large leak... The fuel pellets likely melted and fell, and in the process may have damaged... the pressure vessel itself and created a hole.”

The discovery that the pressure vessel is leaking certainly complicates efforts to permanently stabilise the reactor and prevent the further spread of radiation.

Earthquake main reason for failures?
Meanwhile, evidence is growing that Unit 1’s meltdown was initiated by the earthquake and only exacerbated by the ensuing tsunami. Bloomberg reports that a radiation alarm inside Unit 1 went off before the tsunami even arrived, indicating coolant already had been lost and fuel melting had begun. If true, this could also require a re-assessment of how quickly reactors can melt down. Tepco said May 16, that radiation levels inside Unit 1 were measured at 300 MilliSieverts/hour within hours of the earthquake - meaning that fuel melting already had begun. For melting to have begun that early, coolant must have been lost almost immediately. It’s now believed that fuel melted and dropped to the bottom of the containment - melting a hole into it, within 16 hours. Most likely, a major pipe carrying cooling water to the core was damaged by the earthquake, which should lead to a new evaluation of the ability of key reactor components to withstand seismic events.

According to Arnie Gunderson (a former nuclear industry senior vice president, and energy advisor with 39-years of nuclear power engineering experience) of Fairewind Associates, who is citing a report by Siemens, Unit 4's fuel pool cracked from the earthquake, not from the tsunami.

The Nuclear and Industrial Safety Agency has so far said (as has the international nuclear industry) that the reactor withstood shaking but tsunami of an unexpected scale caused power loss, which led to an explosion.

On May 16, Tepco disclosed internal documents and data indicating the isolation condenser may have been manually shut down around 3 p.m. March 11 following the massive quake at 2:46 p.m. The plant was hit by tsunami around 3:30 p.m.  The isolation condenser is designed to inject water into the reactor for at least eight hours after the main coolant system loses power, as happened March 11. "It is possible that a worker may have manually closed the valve (of the isolation condenser) to prevent a rapid decrease in temperature, as is stipulated by a reactor operating guideline," Tepco spokesman Hajime Motojuku told The Japan Times. A worker may have stopped the condenser to keep cold water from coming into contact with the hot steel of the reactor to prevent it from being damaged.

However, nuclear reactors are designed to withstand this procedure in case of an emergency, said Hiromi Ogawa, a former nuclear plant engineer at Toshiba Corp. According to Tepco, the isolation condenser's valve was confirmed open at 6:10 p.m. March 11 but it is unknown whether it was open between 3 p.m. and 6:10 p.m. The valve was confirmed closed at 6:25 p.m. and confirmed open again at 9:30 p.m. Finally, the condenser was shut down due to a pump malfunction at 1:48 a.m. March 12, roughly eight hours after the tsunami, matching the battery life of the isolation condenser.

Radiation leak before Tsunami?
Only a few days after the revelations about the failure of the cooling before the tsunami hit the plant, another revelation, with possible grave consequences, hit the media.

A radiation monitoring post on the perimeter of the Daiichi plant about 1.5 kilometers from the No. 1 reactor went off at 3:29 p.m., minutes before the station was overwhelmed by the tsunami that knocked out backup power that kept reactor cooling systems running, according to documents supplied by the company. The monitor was set to go off at high levels of radiation, an official said.

“We are still investigating whether the monitoring post was working properly,” said Teruaki Kobayashi, the company’s head of nuclear facility management. “There is a possibility that radiation leaked before the tsunami arrived.” Kobayashi said he didn’t have the exact radiation reading that would trigger the sensor.

Until recently Tepco said the plant stood up to the magnitude-9 quake and was crippled by the tsunami that followed.  This early radiation alarm has implications for other reactors in Japan, one of the most earthquake prone countries in the world, because safety upgrades ordered by the government since March 11 have focused on the threat from tsunamis, rather than earthquakes.

So it's becoming more and more clear that, contrary to earlier assumptions, the reactors were already severely damaged by the earthquake before the tsunami hit the reactors. And that is despite the fact that the earthquake "did not exceed design base values significantly", according to an important Dutch nuclear lobbyist of the Technical University Delft Jan Leen Kloosterman, before news of damage before the tsunami even hit the reactors became public. He put it this way in a meeting on May 13: "If seismic data can be confirmed, practically all damage at Fukushima-Daiichi would have to be contributed to the tsunami." That would suit  them well. Gunderson: "This wasn't, at Fukushima, that big an earthquake. It was, out at sea a nine, but by the time it got to Fukushima, they should have been able to ride out that storm, at least the seizmic issues of it. But what that says is that what we have been relying on in analyzing these plants may not be working. Two out of the four plants developed cracks from an earthquake and they should have been able to get through this."

On May 24, Tepco confirmed finally what everybody except Tepco and the international pro-nuclear community already knew: that fresh data from Units 2 and 3 indicate that fuel rods in those reactors are “in a similar state as that in reactor number 1”. That is: fallen into a lump at the bottom of the pressure vessel. Three melt downs confirmed.

More evacuations; and more to come?
More than 2 months after March 11, residents of Kawamatamachi and Iitatemura, both in Fukushima Prefecture, began evacuating on May 15, to avoid high-level radiation. Farewell ceremonies were held in both municipalities. About 1,200 residents in Kawamatamachi will evacuate from their homes. In Iitatemura, about 4,500 residents will move from the village to accommodations in Fukushima city, such as housing for local government officials and hot spring hotels. Most of Iitatemura is located more than 30 kilometers from the Fukushima No. 1 power plant.

Around 70,000 people, including 9,500 children aged up to 14, live in  the area, "the most contaminated territory outside the evacuation zone," according to a report by France's Institute for Radiological Protection and Nuclear  Safety (IRSN). Updating its assessment of the March 11 disaster, IRSN highlighted an area northwest of the plant that lies beyond the 20-km zone whose inhabitants have already been evacuated. Radioactivity levels in this area range from several hundred  becquerels per square meter to thousands or even several million becquerels per square meter, the IRSN report, issued May 23, said. "These are people who are still to be evacuated, in addition to those who were evacuated during the emergency phase in March," Didier Champion, IRSN’s environment director, told AFP.

Internal contamination after visiting Fukushima
The engineering details of the Fukushima tragedy are beginning to be admitted publicly, while the biomedical details are still being glossed over. With fuel melting, vastly greater amounts of radio-active materials are released from the core than occur with the lesser types of fuel damage that had been postulated earlier.

Dozens of different species of radioactive materials were released in the form of vapours or particulates, susceptible for inhalation or ingestion by humans and animals, likely to be tracked into homes, schools and offices after being deposited in clothing, skin or hair.

The discovery that almost 5000 nuclear workers have now shown signs of internal radioactive contamination after simply visiting the Fukushima site guarantees that Japanese citizens of all ages from the nearby areas have also experienced some degree of internal deposition of radioactive materials in their bodies.  Nursing mothers are now showing measurable amounts of radioactive contamination from Fukushima in their milk.

The decision of the Japanese government to allow children in dozens of schools to be exposed to levels of atomic radiation up to 20 millisieverts per year is irresponsible and deserves to be denounced. Not only are children much more susceptible to the harmful effects of radiation exposure than adults, but they are much more likely to track radioactive contaminants into their homes and schools in the form of dirt and dust, soiled hands and fingernails, and dirty play-clothes.

June 11: Global Day of Action
Meanwhile, anti-nuclear protest continue. On  May 23, furious parents from the Fukushima region and hundreds of their supporters rallied in Tokyo against revised nuclear safety standards in schools (see also Nuclear Monitor 726). Japanese children can now be exposed to 20 times the radiation that was permissible before the March 11 earthquake and tsunami that caused  meltdowns at Fukushima Daiichi. Around 400 protesters, many from areas around the stricken plant, flocked to the education and science ministry to demand a rethink on the new limit, which allows exposure of up to 20 millisieverts a year. A group of Fukushima residents submitted a letter for the education minister demanding the ministry do all it can to lower radiation levels at schools and offer financial support.

Many citizens and groups in Japan have started organizing June 11 actions like demonstrations or parades. The day marks three months after the Fukushima nuclear disaster triggered by the earthquake and tsunami. The plants are still spewing radioactive materials. No one wants such dirty electricity harmful to human and nature.

“Join Japanese groups on June 11th with million-people action throughout the world and let our voice be heard. We need your support to spread our message and hear from as many people on Earth as possible. We appreciate it if you decide to organize your own demonstrations, parades, gatherings, or anything on June 11th or 12th.

Our solidarity, if you are in Japan, in Asia, in Europe, in Americas, or anywhere in this world, will soon end this dark age of nuclear power generation”.

Please, endorse the June 11 actions and list your own action at: http://nonukes.jp/wordpress/?page_id=137
Endorsing groups or organizations will be publicized on the website.

Sources: Mainichi Daily News, 15 & 21 May 2011 / Godon Edwards CCNR, 24 May 2011 / AFP, 24 May 2011 / Japan Times, 17 May / Bloomberg, 12 & 19 May 2011 / Japan Today, 24 May 2011 / http://www.fairewinds.com/content/implications-fukushima-accident-worlds... / Daily Yomiuri Online, 16 May 2011 / NIRS updates / Jan Leen Kloosterman, presentation Fukushima 2011 on 13 May, The Hague, Netherlands, available at: http://www.nrg.eu/docs/kivi/2011/20110513-fukushima-ongeval.pdf (in English)

Contact: Citizens' Nuclear Information Center (CNIC), Akebonobashi Co-op 2F-B, 8-5, Sumiyoshi-cho, Shinjuku-ku, Tokyo, 162-0065, Japan
Tel: +81-3-3357-3800

Email: [email protected]


Fukushima’s temporarily sarcophagus. According to an article in the Daily Mail (U.K.) polyester tents will be placed over the Fukushima Daiichi nuclear reactors in a bid to try and contain the escape of radioactive substances into the atmosphere. In June Tepco will start work on installing the first cover at the Daiichi No.1 reactor. The Japanese government plans to erect a steel framework and place a giant polyester tent-like cover around the reactor building - similar covers will be placed around units 3 and 4.  Work on the huge protective tents is expected to be completed by the end of the year.


 

About: 
Fukushima-Daiichi-1Fukushima-Daiichi-2Fukushima-Daiichi-3Fukushima-Daiichi-4Fukushima-Daiichi-5Fukushima-Daiichi-6