Posts Tagged ‘TEPCO’

Fukushima radioactive water leakage now stopped

April 5, 2011

Update! BBC:

A leak of highly radioactive water into the Pacific Ocean from Japan’s crippled Fukushima Daiichi nuclear plant has been stopped, its operator reports. Tepco said it had injected chemical agents to solidify soil near a cracked pit, from where the contaminated water had been seeping out.

TEPCO reports the first signs that at least one of the leaks has been found and that preventive measures seem to be having some effect according to NHK:

TEPCO has injected a hardening agent beneath a leaking concrete pit in a bid to stem the flow of highly radioactive water into the sea. The firm says the leakage seems to be decreasing, following the infusion of the hardening agent.

The utility showed reporters a photo of the leak on Tuesday evening, saying it indicates such a decrease. TEPCO said it will infuse another 1,500 liters of liquid glass. Tokyo Electric Power Company started infusing liquid glass into gravel below the pit near the Number 2 reactor at 3 PM on Tuesday.

Leakage - before and after: screen shot from NHK

TEPCO spotted a crack in the pit 3 days ago while trying to find the source of the leakage of contaminated water into the Pacific Ocean. Since then, the utility has tried in vein to seal the pit with concrete, or to plug piping leading into it with a polymer mixture. A test using a dye agent showed the possibility that the radioactive water is leaking from a cracked pipe, and then seeping through gravel into the concrete pit.

TEPCO is planning to board up the breached sections of an offshore dike to prevent the tainted water from spreading further into the sea. It is also considering building underwater barriers at 3 locations, including one near a water intake for the Number 2 reactor

Fukushima Dai-ichi: Reactor No.2 suppression pool leaking highly radioactive water

March 27, 2011

BREAKING!

Very high levels of radiation have been measured in water leaking from reactor #2. It is thought that the breach is in the suppression pool.

TEPCO, says it has measured radiation levels of 2.9 GBq/cc in water from the basement of the turbine building attached to the Number 2 reactor. The level of contamination is about 1,000 times that of the leaked water already found in the basements of the Number 1 and 3 reactor turbine buildings. The measurements indicated 2.9 GBq/cc iodine-134, 13 MBq/cc of iodine-131, and 2.3 MBq /cc for each of cesium 134 and 137. This is clear evidence that fission is continuing.

University of Tokyo graduate school professor Naoto Sekimura says the leak may come from the suppression chamber of the Number 2 reactor, which is known to be damaged. The chamber is designed to contain overflows of radioactive substances from the reactor.

All workers have been evacuated from the reactor #2 building.

Radioactive water leaks from 3 reactors – fresh water cooling started

March 25, 2011

The path to complete cooling and stability will not be smooth or easy at Fukushima Dai-ichi nuclear plant. New complications and setbacks in Reactors #1,2 and 3 are leading to new strategies and actions. There will no doubt be many more such challenges in the days and weeks ahead.

Update 25th March midnight JST (1600 CET):

TEPCO said Friday it has begun injecting freshwater into the No. 1 and No. 3 reactor cores at the crisis-hit Fukushima Daiichi nuclear plant to enhance cooling efficiency, although highly radioactive water was found leaking possibly from both reactors as well as the No. 2 reactor.

The latest efforts to bring the troubled reactors at the plant under control are aimed at preventing crystallized salt from seawater already injected from forming a crust on the fuel rods and hampering smooth water circulation, thus diminishing the cooling effect, the plant’s operator said.

A day after three workers were exposed to water containing radioactive materials 10,000 times the normal level at the turbine building connected to the No. 3 reactor building, highly radioactive water was also found in the turbine buildings of the No. 1 and No. 2 reactors.

Early Friday, concern grew that the high-level radiation leak detected with the workers’ exposure Thursday could indicate possible damage to the No. 3 reactor vessel, but the government’s nuclear safety agency later denied the possibility, saying no data, such as on the pressure level, have suggested the reactor vessel has cracked or been damaged. The No. 3 reactor used plutonium-uranium mixed oxide fuel for so-called ”pluthermal” power generation.

While the high-level radiation is suspected to have come from the reactor, where overheating fuel rods are believed to have partially melted, it remains uncertain how the leak occurred, said Hidehiko Nishiyama, spokesman for the government’s Nuclear and Industrial Safety Agency.

He said further verification is needed to find out how the radioactive water reached the underground site where the workers were exposed. Huge volumes of water have been poured into the reactor as well as its apparently boiling spent fuel pool since they lost their cooling functions.

In addition to the infusion of freshwater to the No. 1 and No. 3 reactors, it injected seawater to the spent fuel pools of the No. 2 and No. 4 reactors through pipes, and firefighters sprayed a massive amount of seawater onto the No. 3 fuel pool, the utility said.

The government, meanwhile, encouraged residents within 20 to 30 kilometers of the plant to leave voluntarily, citing concerns over access to daily necessities, while maintaining its directives for them to remain indoors and for residents within 20 km of the plant to evacuate.

Fukushima Dai-ichi diary for Friday 18th: Radiation decreasing – Is the worst over?

March 17, 2011

Today will be one week since the Great Sendai quake and the subsequent tsunami slammed north east Japan. Today will also be a fateful day for the efforts being made to cool the reactors and the spent fuel ponds at the Fukushima Dai-ichi nuclear plant. Though the nuclear plant incident causes much more alarm than anything else the quake and tsunami caused, it is worth bearing in mind that it is still just an incident at the nuclear plant. Radiation leakage has not itself caused any deaths or any destruction so far. If unchecked it has the potential of becoming a disaster but if the eforts to cool the reactor today succeed then it will remain at the level of a very serious nuclear incident caused by the quake and the tsunami.

It needs to be remembered that the massive death and destruction was caused by the quake and the tsunami and has resulted  in 20,000+ killed or missing and the wiping out of whole towns. Over 500,000 are displaced and some have lost everything they owned and many of their families. The nuclear plant incident should not be allowed to divert attention from the dire condition further north.

(Sources for my diary are mainly NHK, Kyodo, Asahi, Reuters, BBC, CNN, AFP, IAEA, JAIF and  a few private sources. Some interpretation of the news reports is necessary since they all seem to have some bias.)

2200 JST (1400 CET): Sendai Airport has been cleared with the help of US forces and is now being used to fly in relief supplies. Considering the pictures of the tsunami wave flowing across the airport one week ago, that itself is remarkable. It is still very cold tonight for the evacuees but warmer weather is expected tomorrow.

No further news conferences scheduled today and no further news which at least means no further deterioration. If power is restored to the nuclear plant during tonight the corner would have been turned, I think.

2100 JST (1300 CET): It looks like water spraying activities are over for the day and the focus is back on connecting the new high voltage power line. Current effort is to connect to a transformer in the reactor building but work times are very short since the radiation level here is about 20 milli Sieverts / hr. Tokyo police and fire fighters are trying to devise a system which allows spraying for long periods using the high capacity fire trucks designed for tall buildings.

A small reduction in radiation was observed when spraying was finished but assessment will take some time.

A description of the quake, tsunami and consequences for the plant operation are well described here.

1900 JST (1100 CET): The authorities are warning of tidal floods in the north east. Due to the earthquake, parts of the coast have sunk and in some areas tides could be 40cm higher than usual. Spring tides will last 8 days but flooding will be slow compared to the tsunami.

1800 JST (1000 CET): Japan’s nuclear safety agency is now calling it a level 5 incident at reactors 1, 2 and 3 of Fukushima Dai ichi, and a level 3 incident at reactor 4. I think the incident at reactor no. 4 where the problems with the spent fuel pond have been so turbulent could be reclassified later to level 4. Three Mile Island was classified at level 5.

The Japanese nuclear agency says it expects electrical cables to be connected at reactors 1 and 2 by Saturday morning.

1700 JST (0900 CET): 5.4 magnitude quake off Ibaraki subjecting Tokyo to some shaking as well.

General Electric has sent nuclear engineers to a Japanese emergency response centre where they are working with Tokyo Electric Power Co. GE designs nuclear reactors, including all six at the Fukushima Dai-ichi plant though the plants were constructed by Toshiba.

Reuters reports that US data collection flights have confirmed that contamination has not spread beyond the 30km zone established by the Japanese Government – which of course begs the question why the US established 80 km as the no-go zone  for their citizens and which was immediately adopted by many other countries. Abundant caution is no doubt the reason but some accompanying explanation would have helped to prevent some of the questioning of the Japanese imposed 30km zone.

Chief Cabinet Secretary Edano explained that the water spraying operations were being carried out in shifts to limit exposure and the further spraying operations would be continuing as the personnel were rotated. No details about the effects were yet available but it seemed clear that the water was reaching the target.

1600 JST (0800 CET): In Severe Accident Management, the key step and that which is being carried out now is the use of water for the removal of heat. More stringent operations include the use of sand or rubble or boron in some form to cover the radiating components. It is not impossible to even consider concrete. But all uses of solid materials would limit any further heat removal and would only come into play if heat removal was considered impossible.

An SDF spokesman said  “We think got water on the main part today” and “Troops doing the work only absorbed a few millisieverts at most” says the Daily Yomiuri. The Assistant Head of the SDF said that the radiation levels did not significantly hamper the water spraying operations.

1500 JST (0700 CET): 7 days have gone since the quake hit.

More fire trucks including US military trucks are on their way. It will probably take a few hours to make any evaluation of the effects of the water spraying. But the amount of steam rising suggests that the water was reaching its target. But the amounts contained in the sprays (total around 50 tons) is small compared to the capacity of the spent fuel ponds (about 1200 tons). Water spraying is to continue.

There are some 180 people working at the site and braving the radiation levels.

1414 JST: 2 more water jets can be seen – apparently the 3rd wave. Steam continues to rise and is “billowing” rather than a plume.

1410 JST (0610 CET): The strong plumes of steam(?) have subsided somewhat and are now more like clouds rising.

1406 JST: One wave of water spray with 2 trucks seems to be over and plumes of steam(?) can be seen rising from the reactor. Something is being cooled.

1400 JST (0600 CET): Water spraying has resumed at reactor no.3 by the SDF. Seven trucks are being used. The water jets are clearly visible from NHK pictures from 30km away and – at least by eye – are much more accurately directed onto the building than yesterdays helicopter drops.

1300 JST (0500 CET): Radiation levels have been consistently falling at one measuring point since the water spraying on Thursday evening. The measurement location is at one station about 1km west of reactor no. 2. The radiation reading at 5 a.m. Friday came to 279.4 microsievert per hour, compared with 292.2 microsievert per hour at 8:40 p.m. At around 9am this was down to 271 micro Sieverts. Thursday. It is not certain that this was due to the water spraying but the situation is at least stable and is not deteriorating. The trend is encouraging.

This morning the focus has been on the power line installation and on Friday at 2pm the water spraying will restart. It seems it was not possible to do both simultaneously. The SDF fire trucks will address reactor no.3 and police fire trucks will be working on reactor no.1. More fire trucks have been despatched from Tokyo. The performance of the trucks is such that helicopter water drops are not being considered. Over 30 trucks are expected to be in operation including trucks especially designed to fight fires in very tall buildings with a water discharge point 22m above street level. But water spraying is only a stop-gap measure and the real stability will only come once the cooling systems and water circulation has been restored.

The new power cables are in place but they now have to be reconnected to the cooling system pumps once the pumping systems have been checked out. Working shift durations are still restricted by the radiation levels. Reactor no.2 systems could be connected sometime during Friday night. Reactors no. 3 and 4 will be next to be reconnected and this is targeted for Sunday.

0600 JST: Summary of the status by Japan Atomic Industry Forum is here Fukushima status 2200 17th March

IAEA Slide show on BWR’s and the Fukushima status is here

18th March – 0500 JST (2100 CET 17th): The spraying of water by the fire trucks (and possibly even the helicopter water dumps) on the evening of the 17th did give some small but measurable decrease in radiation levels at the gate of the power plant. Spraying activities stopped at around 8pm on 17th and will resume this morning. Hopefully the high voltage power line which has now been laid upto the plant can be activated and the cooling systems brought back into operation today. This work will be slow since exposure to radiation leads to very short working shifts. This could take till tomorrow. This makes the spraying operations particularly critical for today to win the time necessary to get the power restored. The plan is for engineers to reconnect power to unit 2 once the spraying of water on the unit 3 reactor building gives some effect. The water spraying operations are being carried out by SDF and police personnel and TEPCO has even come in for criticism from the SDF for insufficient information which could have endangered their personnel.


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