New Fukushima Live Camera

Nuclear plant workers suffer internal radiation exposure after visiting Fukushima

A photograph shows a whole-body counter. (Photo courtesy of the Nuclear and Industrial Safety Agency)

The government has discovered thousands of cases of workers at nuclear power plants outside Fukushima Prefecture suffering from internal exposure to radiation after they visited the prefecture, the head of the Nuclear and Industrial Safety Agency said.

Most of the workers who had internal exposure to radiation visited Fukushima after the nuclear crisis broke out following the March 11 quake and tsunami, and apparently inhaled radioactive substances scattered by hydrogen explosions at the Fukushima No. 1 Nuclear Power Plant.

The revelation has prompted local municipalities in Fukushima to consider checking residents' internal exposure to radiation.

Nobuaki Terasaka, head of the Nuclear and Industrial Safety Agency, told the House of Representatives Budget Committee on May 16 that there were a total of 4,956 cases of workers suffering from internal exposure to radiation at nuclear power plants in the country excluding the Fukushima No. 1 Nuclear Power Plant, and 4,766 of them involved workers originally from Fukushima who had visited the prefecture after the nuclear crisis. Terasaka revealed the data in his response to a question from Mito Kakizawa, a lawmaker from Your Party.

The Nuclear and Industrial Safety Agency said it received the data from power companies across the country that measured the workers' internal exposure to radiation with "whole-body counters" and recorded levels of 1,500 counts per minute (cpm) or higher. In 1,193 cases, workers had internal exposure to radiation of more than 10,000 cpm. Those workers had apparently returned to their homes near the Fukushima No. 1 Nuclear Power Plant or had moved to other nuclear power plants from the Fukushima No. 1 and 2 nuclear power plants.

According to Kakizawa, one worker at the Shika Nuclear Power Plant operated by Hokuriku Electric Power Co. in Ishikawa Prefecture returned to his home in Kawauchi, Fukushima Prefecture, on March 13 and stayed there for several hours. He then stayed in Koriyama in the prefecture with his family for one night before moving out of Fukushima. On March 23, he underwent a test at the Shika Nuclear Power Plant that showed his internal exposure to radiation had reached 5,000 cpm. He was thus instructed by the company to remain on standby. The radiation reading dropped below 1,500 cpm two days later, and then he returned to work.

Another male worker in his 40s told the Mainichi that he had waited at his home, about 30 kilometers from the crippled nuclear plant, following a hydrogen explosion at one of the troubled reactors. He later went through a test which showed his internal exposure to radiation had reached 2,500 cpm. "I think most of the radiation derives from iodine (which has a short half-life), and therefore the radiation reading is expected to drop. But I am worried," the man said.

The local government in Nihonmatsu, Fukushima Prefecture, has received inquiries about internal exposure to radiation from its citizens. In response, it is considering selecting infants and people working mainly outdoors and measuring their internal radiation exposure levels using whole-body counters, officials said.

Internal exposure to radiation lasts longer and carries more risks than external exposure. People are deemed to have had internal exposure if whole-body counters detect over 1,500 cpm of radiation from them. If more than 100,000 cpm of radiation is detected from body surfaces, decontamination is said to be necessary.

A special earthquake-resistant building that serves as a base for emergency workers at the Fukushima No. 1 Nuclear Power Plant had its doors strained by hydrogen explosions at the No. 1 and 3 reactors in March, making it easier for radioactive substances to come in. "We had meals there, so I think radioactive substances came into our bodies," a male worker in his 40s said. "We just drink beer and wash them down," he added.

A 34-year-old male worker, who entered the nuclear complex earlier in May, voiced concerns over the lack of a sufficient system to check internal exposure to radiation. "Most of the workers around me have not undergone checkups at all. Those in their 20s are particularly worried," he said.

Tokyo Electric Power Co. (TEPCO), the operator of the crippled Fukushima No. 1 Nuclear Power Plant, is to check workers' internal exposure to radiation whenever deemed necessary, in addition to regular checks conducted every three months. But as of May 16, only about 1,400 workers have gone through checkups -- roughly 20 percent of the total number of workers. And only 40 of the workers have had their test results confirmed. The highest level of radiation to which a worker has been exposed so far is 240.8 millisieverts, and 39 millisieverts of radiation was from internal exposure.

Click here for the original Japanese story

(Mainichi Japan) May 21, 2011

End of the world 2011

Tokyo Electric Power Company, TEPCO, the operators of the Fukushima Daiichi nuclear power plant, have released the first analysis on the condition of the troubled power plant, and their conclusions are relatively grim. This analysis covers only Reactor 1, since it is the only reactor for which the necessary sensor data is available, but it is indicative of the problems faced at the other troubled reactors.

The analysis confirms what most already expected: the fuel in Reactor 1 melted down completely. According to the data from TEPCO, this melting occurred immediately, with almost the entire core having melted down by 16 hours after the earthquake. In a mere five hours or so, the temperature in the core rose from the stable operating temperature of 750 degrees Celsius to a high of nearly 3000 degrees. At this temperature, fuel rods melted completely and fell to the bottom of the reactor vessel.

This meltdown may have saved the reactor, as the bottom of the reactor vessel was the only area being cooled by water injection. Without this limited cooling, the heat might have caused a failure of the reactor vessel. Oddly enough, similar behavior has occurred in other near-meltdowns, in which fuel melting to the bottom of the vessel helped prevent the vessel from failing. This was the case with the partial meltdown of TMI-2 at Three Mile Island in 1979.

It is a sign of just how unstable the situation remains that the reactors have not yet reached cold shutdown. Cold shutdown is achieved when a reactor’s coolant can be depressurized, which requires that temperatures fall below 100 degrees Celsius. Despite two months of seawater and freshwater pumping, temperatures in parts of Fukushima Reactor 1 are still above boiling. So long as temperatures remain this high, water injection will have to continue, which is not ideal.

The problem with continued water injection is that major leaks in the reactor vessel have yet to be stopped. This means that radioactive water continues to leak at a high rate from the reactor, which poses the threat of groundwater contamination. If TEPCO is lucky, most of this water has been contained in the basement of the reactor building, but this still poses a threat to cleanup workers.

TEPCO’s analysis is a testament to the damage sustained by the plant in the first hours after the Tsunami, and somewhat of a relief: reactor vessels held despite temperature stresses above their design capacity, and all the radioactive fuel appears to have remained in the reactor. While TEPCO has not yet released data for the other two troubled reactors, it seems likely that they suffered similar fates to Reactor 1. If this is indeed the case, then Fukushima is a grim warning of just how bad things can go wrong.

Fukushima Daiichi Diary

By PHRED DVORAK And YUKA HAYASHI

A Wall Street Journal examination of the first 24 hours after the Fukushima Daiichi accident shows that disaster piled on disaster, worsening the nuclear crisis faster than anyone had initially thought could happen. Here's a more detailed look at some of the other problems that the stricken plant, regulators and operator Tokyo Electric Power Co. were grappling with.

The Shut-Off Cooling System

Documents released by Tepco Monday showed the isolation condenser— an emergency cooling system installed on Reactor No. 1 before the quake as a final resort in case of a total loss of power—worked only sporadically, if at all. Tepco officials explained that somebody appears to have manually closed the valves on the condenser soon after the March 11 quake—but before the tsunami hit about an hour later—to control the fluctuating pressure inside the reactor. Reopening the valves required battery power, so those valves likely couldn't be opened because the tsunami damaged the backup batteries.

If the valves hadn't been shut, things might have turned out differently. Temperatures in the reactor climbed faster than initially expected, causing more and faster damage. Tepco admitted this week the problems at Reactor 1 were far worse than originally thought. Its new projection shows fuel may have started melting rapidly only five hours after the March 11 quake. By 6:50 a.m. March 12, the fuel was likely in a heap at the bottom of the vessel.

The Offline Off-Site Center

The government's emergency response was to be coordinated out of an off-site center run by regulator Nuclear and Industrial Safety Agency, a 15-minute drive from the Fukushima Daiichi plant. But when Kazuma Yokota, the regulator charged with setting up the center, arrived at the site after the earthquake, he found that phone lines and cellphones were down, the satellite phone wasn't working and the fuel pump supplying the backup power generator was broken. That effectively cut off the office from the outside world during key early hours.

Tepco's emergency-communications systems were still up: Fukushima Daiichi's earthquake shelter was far enough inland to have escaped the tsunami flooding, so its generator powered a video link with Tokyo as well as a special phone system internal to Tepco. But with NISA's off-site center offline, the government was left to shepherd the crisis from Tokyo and depend on Tepco headquarters for its information—something that was to cause crossed signals and mounting frustration later. Mr. Yokota himself had to send staff back to the plant in order to keep tabs on what was going on; the NISA generator wasn't fixed until around 2 a.m. March 12, and it ran out of fuel within a day.

The False Positive at Reactor No. 2

At 8:35 p.m. on March 11, Tepco reported to the government what it thought was the first sign of serious trouble at Fukushima Daiichi: the final emergency cooling system at Reactor No. 2 appeared to have stopped. Experts at NISA threw together a projection showing that fuel in the reactor could start melting by around 1 a.m. By 9:23 p.m., the national government was ordering the evacuation of people within two miles of the plant. The Fukushima prefectural government, unwilling to wait so long, had already issued its own order about a half hour earlier.

In fact, as is now known, the real problem was at Reactor 1. Toward midnight, Fukushima Daiichi engineers were reporting that the cooling system at Reactor 2 had restarted, but had stopped at Reactor 1. Tepco recently admitted Reactor 1's fuel rods were likely exposed by around that time.

Lost in Transit

According to company protocols, the decision to vent radioactive gas from a reactor had to be made by Tepco's president, Masataka Shimizu. Around the time Tepco's engineers and the government were coming to that decision, though, Mr. Shimizu was stuck in the city of Nagoya, about 165 miles west of Tokyo, after trying unsuccessfully to get back to headquarters following the quake. Around 9:30 p.m., Mr. Shimizu had asked for a military transport flight back to the capital only to be denied permission by the Minister of Defense. Officials said the aircraft was needed instead to fly supplies to the tsunami zone. At 12:13 a.m.—around the time Fukushima Daiichi engineers were getting their alarming reactor-pressure reading at Reactor 1—the plane landed again in Nagoya.

Polluting the Air

In a sign of how far-fetched a crisis of this magnitude was considered, Tepco didn't take the extra step of installing a filter on its emergency vent pipe to scrub out radioactive particles. Indeed, the whole vent installation was considered voluntary, since Japanese regulators didn't think nuclear reactors would ever have to deal with the high pressures the vent system was designed to withstand. That meant venting would be accompanied by the release of significant amounts of radioactivity in the air. Before the venting, the government expanded the evacuation zone to six miles from the two miles set the night before. Tepco attributes much of its venting delay to concerns about the evacuation.

"As someone who knows a little bit about nuclear energy, I knew how urgent it was to vent," said Masashi Katayose, a 57-year-old engineer in the Fukushima prefectural government's nuclear safety section. "But as local officials, we can't say, 'go ahead and contaminate our air with radiation.'" When Mr. Katayose and others broke the news of the venting to the governor, he just nodded.

Pump Problems

Tepco workers wanted to make sure they could inject more water into the reactor as they vented. The venting process could aggravate the cooling problems by further lowering water levels in the reactor, because venting releases water in the form of steam and because water boils at higher temperatures when under higher pressure. But that faced obstacles, too, Tepco officials said. At least one of the fire trucks that would normally have been used to pump water into the reactor had been washed away by the tsunami. When the ground crew did get fire hoses hooked up to Reactor 1, they had trouble getting the water in, Tepco officials said.

Tepco didn't manage to start pumping fresh water into the reactor until 5:46 a.m. on March 12. Workers called off the operation around 3 p.m.—half an hour before the hydrogen explosion—after injecting around 80 tons, Tepco documents released Monday showed.

Taking Turns

Radiation levels at Reactor 1 were so high by the time workers went in to open vent valves manually that they had to go in short shifts to prevent high exposure. The Reactor 1 shift manager's stint exposed him to 100 times the radiation an average person gets in a year. Then, several workers followed him one by one, relay style, to turn the crank little by little. At 9:15 a.m. Saturday , the valve was open a quarter of the way, Tepco documents released Monday say.

Radiation levels delayed attempts to open the second, air-operated valve as well, Tepco officials said. They went in short shifts, carrying a portable air compressor and a power source into reactor building and hooking it up in the darkness.

A total of 18 workers were exposed to radiation that day, NISA documents say, though none were reported to have suffered any health problems. The shift manager reported a headache and was seen by doctors, but he was later sent home.

Radioactive Tea

Farmers in Kanagawa Prefecture have begun disposing of tea leaves that were tainted by radioactive material from the troubled Fukushima Daiichi nuclear plant, more than 250 kilometers away.

Radioactive cesium above the designated safety limit was detected earlier this month in tea leaves harvested in 6 municipalities in Kanagawa, neighboring Tokyo.

The prefectural government asked the municipalities and local farmers' cooperatives to voluntarily halt shipments of tea leaves.

Farmers in Kiyokawa Village began stripping their tea trees of leaves following the announcement.

The prefectural government has asked farmers to place the harvested leaves as far as possible from the trees until it decides with the central government how to dispose of them.

One farmer says he wants to get rid of the contaminated leaves as soon as possible to protect the entire plantation.

Tuesday, May 17, 2011 08:25 +0900 (JST) NHK

Fukushima: ampliata la zona di evacuazione. La centrale ancora fuori controllo

I tecnici della Tepco hanno dovuto abbandonare il tentativo di stabilizzare il reattore N.1 a causa di una “fuga” di tremila tonnellate di acqua contaminata. Evacuati cinquemila residenti di Kawamata e Iitate, città a oltre 30 km dalla centrale danneggiata dal sisma.


Tokyo (AsiaNews/Agenzie) – La zona di sicurezza intorno alla centrale nucleare di Fukushima si è ampliata, e l’operazione per riportare sotto controllo l’impianto è stata bloccata. I residenti delle città di Kawamata e di Iitate hanno passato la loro prima notte nei centri di evacuazione dopo aver abbandonato le abitazioni. I tecnici giapponesi nel frattempo hanno abbandonato il tentativo che stavano compiendo di stabilizzare uno dei reattori danneggiati dal terremoto e dalla tsunami dell’11 marzo.
Kawamata e Iitate sono a più di 30 km di distanza dalla centrale, da cui continuano fughe di materiale radioattivo. Circa cinquemila persone si sono spostate in edifici pubblici, alberghi e altre sistemazioni nelle città vicine. Ci si attende che le evacuazioni aumentino nei prossimi giorni. Mentre gli sforzi per riportare sotto controllo la centrale danneggiata si scontrano continuamente con nuovi problemi.
I tecnici della Tokyo Electric Power Company (Tepco) volevano raffreddare il reattore N.1 con l’acqua. Ma le barre di combustibile fuso hanno creato un buco nella parete della stanza, permettendo così a tremila tonnellate di acqua contaminata di disperdersi nei locali sottostanti. La Tepco ha dichiarato che il piano per cercare di stabilizzare in 6-9 mesi la centrale di Fukushima non è più possibile, La TEPCO sta ora studiando un nuovo piano.

Kamikaze nuclear workers by TEPCO

Tokyo - (PanOrient News) The operator of the crippled Fukushima Daiichi nuclear power plant, Tokyo Electric Power Co., or TEPCO, concealed data showing surges in radiation levels at the Fukushima No. 1 nuclear power plant in March, one day before a hydrogen explosion injured seven workers, the daily Asahi Shimbun reported.

The paper cited a 100-page internal TEPCO report containing minute-to-minute data on radiation levels at the plant as well as pressure and water levels inside the No. 3 reactor from March 11 to April 30.

This is certain to make another blow to the company image that is shattered by its handling of the worst nuclear accident in Japan's history.

The unpublished information shows that at 1:17 p.m. on 13 March, 300 millisieverts of radiation per hour was detected inside a double-entry door at the No. 3 reactor building. At 2:31 p.m., the radiation level was measured at 300 millisieverts or higher per hour to the north of the door. Both levels were well above the upper limit of 250 millisieverts for an entire year under the plant's safety standards for workers.

“But the workers who were trying to bring the situation under control at the plant were not informed of the levels.” 

Government preparing N-crisis road map

The Yomiuri Shimbun

The government is preparing a road map on its measures related to the nuclear crisis at the Fukushima No. 1 power plant, including assistance for victims and restoration of the areas contaminated by radiation from the plant, it has been learned.

The road map will stipulate that a third-party panel will investigate the crisis and draw up an interim report by the end of this year, sources said. Prime Minister Naoto Kan recently announced creation of the panel.

The government plans to adopt the road map on Tuesday at its Nuclear Emergency Response Headquarters, according to sources. On the same day, Tokyo Electric Power Co. plans to announce a revision of its road map for stabilizing the nuclear reactors at the Fukushima No. 1 power plant. TEPCO announced its initial road map on April 17.

By announcing its road map on the same day, the government aims to highlight its measures, according to the sources.

The third-party panel will investigate the cause of the nuclear accident and discuss measures to prevent similar accidents. It will also review the government's and TEPCO's handling of the nuclear crisis.

The government plans to stipulate in its road map that full-fledged restoration activities for areas contaminated by radiation from the Fukushima No. 1 nuclear plant will begin by autumn, so that the rebuilding activities in the areas will not lag behind those in other areas hit by the March 11 earthquake and tsunami, the sources said.

In its initial road map, TEPCO said it would seek to significantly reduce the amount of radioactive substances from the crippled nuclear complex within six to nine months. However, various newly-emerged factors forced the utility firm to review the plan.

(May. 16, 2011)

Another worker dies at Fukushima plant

The cause of the worker's death was unknown. The man, in his 60s, was employed by one of Tokyo Electric's contractors and started working at the plant on Friday. He was exposed to 0.17 millisieverts of radiation on Saturday, Tokyo Electric said.

The Japanese government's maximum level of exposure for male workers at the plant is 250 millisieverts for the duration of the effort to bring it under control.

The worker fell ill 50 minutes after starting work at 6:00 a.m. on Saturday (5 p.m. EDT on Friday) and brought to the plant's medical room unconscious. He was later moved to a nearby hospital and confirmed dead, a Tokyo Electric spokesman said.


Maybe wasn't 0.17 millisieverts/hour but more! Tepco no more lies!

Japan nuclear: Tepco make a retreat from Fukushima

Japanese engineers have abandoned their latest attempt to stabilise a stricken reactor at the Fukushima nuclear plant.

The plant's operator, Tepco, had intended to cool reactor 1 by filling the containment chamber with water.

But Tepco said melting fuel rods had created a hole in the chamber, allowing 3,000 tonnes of contaminated water to leak into the basement of the reactor building.

The power plant was badly damaged by the earthquake and tsunami on 11 March.

Cooling systems to the reactors were knocked out, fuel rods overheated, and attempts to release pressure in the chambers led to explosions in the buildings housing the reactors.

The government and Tepco (Tokyo Electric Power Company) said it would take until next January to achieve a cold shut-down at the plant.

Government spokesman Goshi Hosono said the latest setback would not affect the deadline.

"We want to preserve the timetable, but at the same time we're going to have to change our approach," he said.

Tepco says it will come up with a new plan to stabilise the reactor by Tuesday.

Japanese broadcaster NHK said Tepco was now studying a plan to circulate water from the basement through a decontamination filter and back into the reactor.

The earthquake and tsunami killed thousands of people and left many more homeless.

The tsunami flattened buildings in fishing villages and port towns, and swept debris miles in land.

Last week the government agreed a huge compensation package for those affected by the disaster.

Analysts say the final bill for compensation could top $100bn (£61bn).

Meltdown occurred at Fukushima No. 1 reactor 16 hrs after March 11 quake.

TOKYO, May 15, Kyodo

A nuclear fuel meltdown at the No. 1 reactor of the crisis-hit Fukushima Daiichi power plant is believed to have occurred around 16 hours after the March 11 quake and tsunami crippled the complex in northeastern Japan, Tokyo Electric Power Co. said Sunday.

The utility revealed its study on the subject on Sunday.

TEPCO said it analyzed the data and calculated a timeline for the developments in the No. 1 reactor on the assumption that the reactor lost its cooling system as soon as it was hit by the tsunami.

The firm said that within about 3 hours after the reactor automatically shut down, the cooling water had evaporated to a level at the top of the rods.

In the next hour and a half, parts of the fuel rods are believed to have begun melting.

The temperature of the fuel rods is believed to have reached 2,800 degrees Celsius at this stage, and the meltdown advanced rapidly.

Almost of all the fuel rods melted and dropped to the bottom of the pressure vessel by 6:50 am on March 12th.

TEPCO said the temperature dropped after water was poured into the reactor starting at 5:50 am on the same day.

The firm says the melted rods created small holes on the bottom of the vessel, but that no major problems are developing there. It believes that the amount of radioactive substances that could spread from the reactor will be limited.

Sunday, May 15, 2011 23:29 +0900 (JST)

Fukushima Media News

Tokyo, 14-05-2011

Una notevole quantita' di acqua e' stata trovata nei sotterranei dell'edificio che ospita il reattore 1 della disastrata centrale nucleare giapponese di Fukushima, facendo ipotizzare che si tratti di liquido altamente radioattivo uscito dal contenitore di pressione, danneggiato dalla fusione del combustibile nucleare.
Secondo quanto riferito oggi dall'Agenzia per la sicurezza nucleare nipponica, l'acqua, scoperta ieri da un tecnico nei pressi di una scala che conduce al piano inferiore dell' edificio, e' stata stimata a un'altezza di oltre quattro metri.
Giovedi' i tecnici della Tepco, la societa' gestrice della centrale, avevano scoperto che l'acqua di refrigerazione all'interno del contenitore di pressione del reattore 1 e' a un livello molto piu' basso di quanto stimato, lasciando completamente scoperte le barre di combustibile nucleare e andando possibilmente a causare un parziale "meltdown" (fusione), che avrebbe lesionato il fondo della struttura.
L'acqua trovata nei sotterranei spiegherebbe inoltre il livello estremamente basso di liquido refrigerante nel reattore, nonostante vi siano state immesse finora oltre 150 tonnellate di acqua. L'Agenzia per la sicurezza nucleare ha anche riferito che, sempre ieri, nella zona sud-est al piano terra dello stesso edificio un robot telecomandato ha rilevato un livello di radiazioni estremamente alto, pari a circa 2.000 millisievert/ora, il valore massimo fin qui registrato. Fonte Rainews24

Notizie da Fukushima

Ancora alto l'allarme nucleare alla centrale Fukushima Daiichi, danneggiata l'11 marzo dopo il terremoto e lo tsunami. Sono passati due mesi, ma di fatto la situazione non è affatto stabilizzata, la centrale continua a contaminare con acqua radioattiva l'Oceano. Lo stato del reattore numero 1 desta grosse preoccupazioni: i tecnici della Tepco hanno rilevato che manca l'acqua necessaria a coprire le barre del combustibile nucleare. L' acqua non si trova per via di un buco nella campana di contenimento del nocciolo del reattore causato dalla fusione delle barre nucleari, che quindi ora stanno fondendo sul fondo del reattore come a Chernobyl, in più l' acqua altamente contaminata potrebbe sversarsi direttamente nell' Oceano come già appurato per il reattore n.2 (Fine marzo) e reattore n.3 (pochi giorni fa la conferma ufficiale).  La conferma viene dal ministro dell'Economia del Commercio e dell'industria, Banri Kaieda, che sul network tv giapponese NHK ha affermato che "l'acqua pompata all'interno del reattore numero 1 fuoriesce a causa di uno o piu' buchi provocati dalla fusione". I tecnici Tepco hanno calcolato che il livello dell'acqua e' di 5 metri al di sotto delle barre, nonostante ne siano pompate ogni ora 8 tonnellate. Nel bollettino di ieri la Tepco ha detto che ha iniziato a realizzare un sarcofago per contenere il reattore n.1 come avvenne nel 1986 a Chernobyl, al fine di impedire all'acqua radioattiva di fuoriuscire provocando danni incalcolabili per l'ambiente. from (AGI) Cau/Uba