Last updated on March 1, 2013
Läges sammanfattning så här nu på kvällskvisten. TEPCO har medelat att de återigen pumpar havsvatten in i reaktorerna, man får förmoda att ventilen som hade slagit igen av okänt skäl återigen är öppen, eller attt de kommit på ett sätt att komma runt det. De är som vanligt(tyvärr) väldigt sparsamma med den information som ges ut.
För varje dag som går så blir det lättare och lättare att hantera restvärmen och för varje timme de håller vattennivåerna ok så är man ett steg närmare att klara situationen. Trots frekventa bakslag så presterar japanerna fantastiskt väl. Jag kan inte föreställa mig pressen hos de som sitter i kontrollrummen nu och gång på gång hanterar allt. Jag hoppas de alla får medaljer efter detta.
Det är nedslående att se hur så många i bloggvärlden försöker utnyttja situationen att sprida sin antikärnkraftspropaganda. Smaklöst, men positivt nog så är det många som kommenterar galenheten i vad de skriver. I en stund då alla energikällor havererat katastrofalt, där raffinaderier exploderar, naturgasledningar brinner och vattendammar spolar byrt byar, då fokuserar dom helt och hållet på kärnkraft. Den energikälla som hittills orsakat minst förödelse och vars utsläpp hittills varit små och ofarliga. Kan man säga desamma om de brinnande raffinaderierna? Vars är ropen över att lägga ner svensk vattenkraft på grund av dammhaveriet i Japan? Smaklöst att utnyttja situationen på det sättet i ett billigt försök att sprida obefogad skräck och tvivel. Depleted Craniums call to arms är värd att läsa mer än en gång!
Det är dags att säga godnatt för mig för idag om inte något nytt stort händer. Här är en bra sida med statusuppdateringar.
Energy from thorium har lagt upp en riktigt bra kurva över sönderfallsenergin och en bra Q&A. Den är för en 3000 MW reaktor, så halvera det för att få effekten för Fukushima Daiichi 1 och dra bort ungefär 30% for Fukushima Daiichi 2 och 3.
Work resumed early Tuesday morning to inject seawater into a troubled reactor unit at the quake-hit Fukushima No. 1 nuclear power plant in a bid to prevent overheating of fuel rods, Tokyo Electric Power Co. said.
As of 3 a.m., pressure inside the pressure container of the reactor dropped and seawater is believed to be pumped in, but it has not been confirmed that water levels have risen, TEPCO said.
The No. 2 reactor automatically shut down after a massive earthquake that hit the region on Friday. Its reactor cooling function was lost on Monday and water levels rapidly dropped, exposing fuel rods for around two and a half hours from 6:30 p.m.
Seawater was injected and water levels were increased temporarily but started dropped to fully expose them again late Monday night.
Pressure inside the container that houses the rods increased after the container’s steam vents were closed for some reason, preventing seawater injection, it said.
At 1:10 a.m. Tuesday, TEPCO opened some steam valves and resumed work to pump seawater and is considering opening more valves, according to the company.
With radiation levels around the facility risen, TEPCO is suspecting the reactor cores have partially melted, a critical nuclear safety situation.
Work resumed early Tuesday morning to inject seawater into a troubled reactor unit at the quake-hit Fukushima No. 1 nuclear power plant after a steam vent of the pressure container was opened, Tokyo Electric Power Co. said.
Fuel rods became fully exposed again at the No. 2 reactor late Monday night after workers recovered water levels to cover half of them in a bid to prevent overheating, according to the utility.
A series of troubles have been reported at the nuclear power plant in a Pacific coast region in Fukushima Prefecture following a massive tsunami triggered by a catastrophic earthquake on Friday.
(Reuters) – The risk of a major radiation leak in Japanis subsiding as stricken nuclear reactors cool, but there will be major clean-up costs and three reactors will probably be written off, experts said on Monday.
A massive earthquake and tsunami on Friday knocked out cooling systems at a nuclear plant in Fukushima, eastern Japan, triggering a race to flood reactor cores with seawater and stop radioactive uranium fuel from melting and leaking out.
A natural decaying process means that the amount of heat the fuel produces has fallen dramatically, by more than 90 percent, experts said on Monday.
That reduced the chance of serious damage, especially after workers flooded the three worst-affected reactors with seawater.
“The longer it goes on, the better the situation,” said Robin Grimes, director of the Center for Nuclear Engineering at Imperial College London, asked about the chances of a breach of the steel core, or “pressure vessel,” that contains the fuel.
All affected power plants, including the one in Fukushima, stopped generating power automatically when the quake struck.
That left a hot fuel mixture of radioactive materials, such as uranium, plutonium, strontium and cesium, to cool or “decay” over time.
“It’s entirely credible that the worst-case now does not involve break-out of a pressure vessel,” said Malcolm Grimston, nuclear policy and technology expert at the British think-tank Chatham House.
A breach of the core would increase local radiation but it was unclear to what levels. Japan could not repeat the Chernobyl disaster because the Japanese reactors successfully shut down.
At the Chernobyl nuclear plant in Ukraine in 1986, control rods failed to limit the production of heat — the process in which high-energy neutrons smash atoms into pieces in a chain reaction — leading to blasts which blew the reactor apart, spreading contamination across Ukraine, Russia and Europe.
The core of a nuclear reactor consists of metal rods containing pellets of uranium fuel bundled into fuel assemblies, all contained within a steel shell.
The fuel in the Japanese reactors may now not melt through the steel container, but the individual rods were probably damaged.
“I’d be amazed if one or two hadn’t split,” said Grimes.
A more serious meltdown, where the rods congealed into a mess which was hard to remove, would increase the cost of clean-up. That happened at Three Mile Island in Pennsylvania in 1979, where the site had to be sealed.
“It becomes much more complicated, you need much more radiological protection, you’ll probably need to develop new bespoke techniques and that’s where the expense piles up,” said Grimston.
(Reuters) – The United Nations atomic watchdog said on Monday there were no signs, at the moment, that fuel was melting at the Japanese nuclear plant stricken by a huge earthquake and tsunami.
“I think at this time we don’t have any indication of fuel …currently melting,” James Lyons, a senior nuclear safety official at the International Atomic Energy Agency (IAEA), told a news conference on the situation in Japan.
IAEA Deputy Director General Denis Flory said radiation monitored around the Fukushima plant had peaked early in the European day on March 12 and then fallen again that day.
Lite goda nyheter från det andra kraftverket, Fukushima Daini
Restoration work in reactor cooling function that was conducted to
achieve reactor cold shutdown has been completed and cooling of the
reactor has been commenced at 1:24 am, Mar 14th.
Restoration work in reactor cooling function that was conducted to
achieve reactor cold shutdown has been completed and cooling of the
reactor has been commenced at 7:13 am, Mar 14th.
Reactor cold shutdown at 12:15pm, Mar 12th
Restoration work in reactor cooling function is in progress to achieve
reactor cold shutdown
A crisis continued Tuesday at the troubled No. 2 reactor at the quake-hit Fukushima No. 1 nuclear power plant, as fuel rods became fully exposed again after workers recovered water levels to cover half of them in a bid to prevent overheating.
The plant operator, Tokyo Electric Power Co., said a steam vent of the pressure container of the reactor that houses the rods was closed for some reason, raising fears that its core will melt at a faster pace. It said it will try to open the vent to resume the operation to inject seawater to cool down the reactor.
Despite its earlier attempt to do so, however, water levels sharply fell and the fuel rods were fully exposed for about 140 minutes in the evening as a fire pump to pour cooling seawater into the reactor ran out of fuel and it took time for workers to release steam from the reactor to lower its pressure, the government’s nuclear safety agency said.
Water levels in the No. 2 reactor later went up to cover more than half of the rods that measure about 4 meters at one point. TEPCO began pouring coolant water into the reactor after the cooling functions failed earlier in the day.
Prior to the second full exposure of the rods around 11 p.m., radiation was detected at 9:37 p.m. at a level twice the maximum seen so far — 3,130 micro sievert per hour, according to TEPCO.
To ease concerns, Chief Cabinet Secretary Yukio Edano said he believes the problem at the plant ”will not develop into a situation similar to the (1986 accident at the atomic power reactor in) Chernobyl” in the Soviet Union, even in the worst case.
Officials of the Nuclear and Industrial Safety Agency also said the worst case scenario will be less destructive than the Chernobyl incident, as TEPCO has depressurized the reactors by releasing radioactive steam.
The utility said a hydrogen explosion at the nearby No. 3 reactor that occurred Monday morning may have caused a glitch in the cooling system of the No. 2 reactor.
Similar cooling down efforts have been made at the plant’s No. 1 and No. 3 reactors and explosions occurred at both reactors in the process, blowing away the roofs and walls of the buildings that house the reactors.
Edano denied the possibility that the No. 2 reactor will follow the same path, as the blast at the No. 3 reactor opened a hole in the wall of the building that houses the No. 2 reactor. Hydrogen will be released from the hole, he said.
The blast earlier in the day injured 11 people but the reactor’s containment vessel was not damaged, with the government dismissing the possibility of a large amount of radioactive material being dispersed, as radiation levels did not jump after the explosion.
TEPCO said seven workers at the site and four members of the Self-Defense Forces were injured.
Since the magnitude 9.0 quake hit northeastern Japan last Friday, some reactors at the Fukushima No. 1 plant have lost their cooling functions, leading to brief rises in radiation levels.
As a result, the cores of the No. 1 and No. 3 reactors have partially melted.
The government ordered residents within a 20-kilometer radius of the plant to evacuate Saturday in the wake of the initial blast at the plant’s No. 1 reactor. A total of 354 people are still attempting to leave the area, according to the nuclear agency.
The agency ruled out the possibility of broadening the area subject to the evacuation order for now.
Reuters säger att vatteninpumpningen till 2an fungerar igen. Men jag har inte kunnat bekräfta det i något japanskt media eller genom TEPCO’s statusuppdateringar.
Vattennivån har sjunkit igen på 2an
Tokyo Electric Power Co. said Monday fuel rods were fully exposed again in the No. 2 reactor of the Fukushima No. 1 nuclear power plant as of 11 p.m.
TEPCO said a steam vent of the pressure container of the reactor that houses the rods was closed for some reason, leading to a sudden drop in water levels inside the reactor.
It is premature for the technical community to draw conclusions from the earthquake and tsunami tragedy in Japan with regard to the U.S. nuclear energy program. Many opposed to nuclear power will try to use this event to call for changes in the U.S. Japan is facing beyond a “worst case” disaster since we, the technical community, did not hypotheses an event of this magnitude. Thus far, even the most seriously damaged of Japan’s 54 reactors have not released radiation at levels that would harm the public. That is testament to the way professionals in our profession operate: our philosophy of defense in-depth, excellent designs, high standards of construction, conduct of operations, and most important the effectiveness of employees in following emergency preparedness planning.
Trycket i inneslutningen verkar stabilt.
Pressure readouts from the period after the explosion were within a relatively normal range: 380 kPa at 11.13 and 360 kPa at 11.55am. These compare with comfortable levels yesterday of 250 kPa, reference levels of 400 kPa, and a high of 840 kPa recorded at unit 1 on 12 March.
Senaste TEPCO uppdateringen.
At approximately 11:01am, an explosion followed by white smoke occurred at the reactor building of Unit 3. It was believed to be a hydrogen explosion. According to the parameter, it is believed that the reactor containment vessel remains intact. However, the status of the plant and the impact of radioactive materials to the outside environment are presently under investigation. (previously announced) As of 1:30 pm, 4 TEPCO employees and 3 workers from other companies have sustained injuries (all of them are conscious). 3 ambulances are in operation to care for them and 2 have already dispatched the casualties to the hospital. As of 0:30 pm, the measured value of radiation dose near MP6 was 4μSv/h. The increase of the radiation dose cannot be confirmed at this time. As of 0:30 pm, the measured value of radiation dose at the monitoring post in Fukushima Daini Power Station located approximately 10 km south of Fukushima Daiichi Power Station remains at the same level. In light of the incidents that have occurred at Units 1 and 3, we are considering applying prevention measures to the wall of the reactor building to ventilate the hydrogen gas contained in Unit 2. TEPCO continues to take all measures to restore the safety and security of the site and are monitoring the site's immediate surroundings.
Rätt bra videosnutt som förklarar vad som hänt
TEPCO bekräftar bränsleskador.
Reuters rapporterar att bränsleknippena i Fukushima Daiichi reaktor 2 är helt avtäckta och att man börjat pumpa in havsvatten för att åter täcka dom. Detta är mycket allvarligt och kan leda till härdsmälta.
Fuel rods at the No. 2 reactor of the Fukushima No. 1 nuclear plant were fully exposed Monday, following Friday’s deadly earthquake, Tokyo Electric Power Co. said.
The plant operator said water levels fell as fuel for pumps that are used for seawater injection operations ran out.
Tokyo Electric earlier said the cooling functions of the reactor had been lost and began injecting seawater into the reactor to cool it down.
IAEA om explosionen i 3an. Det verkar som att inneslutningen klarade smällen, precis som efter explosionen vid 1an. Kontrollrummet är ännu intakt. Inga förhöjda stråldoser runt verket. Just nu ligger det på 0.02 mSv/timme vilket är ungefär 20-30 ggr över normala bakgrundsstrålningen. Inga utsläpp har alltså skett än så länge, de nivåerna har sitt upphov i ventilationen av inneslutningarna som skett tidigare.
Chief cabinet secretary Yukiyo Edamo appeared on television shortly afterwards to identify the blast was a hydrogen explosion. He said contact had been made with the plant manager whose belief is that the containment structure, important to nuclear safety, remains intact. The rationale for that statement, Edamo said, was that water injection operations have continued and pressure readings from the reactor system remained within a comfortable range.
Japan Earthquake Update (14 March 2011 07:00 CET)
Japan’s Nuclear and Industrial Safety Agency (NISA) has provided the IAEA with further information about the hydrogen explosion that occurred today at the unit 3 reactor at the Fukushima Daiichi nuclear plant. A hydrogen explosion occurred at unit 3 on 14 March at 11:01AM local Japan time.
All personnel at the site are accounted for. Six people have been injured.
The reactor building exploded but the primary containment vessel was not damaged. The control room of unit 3 remains operational.
The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.
At approximately 11:01am, an explosive sound followed by white smoke occurred at the reactor building of the Unit 3. It was believed to be a hydrogen explosion. According to the parameter, it is estimated that the reactor containment vessel remains intact. However, the status of the plant and the impact of radioactive materials to the outside environment are presently under investigation. (previously announced) As of 12:00 am, 4 TEPCO employees and 2 workers of related companies have sustained injuries (all of them are conscious) and ambulances are on their way to care for them. As of 11:44 am, the measured value of radiation dose near MP6 is 20μSv/h and the radiation level remains stable. TEPCO continues to take all measures to restore the safety and security of the site and are monitoring the site's immediate surroundings.
Reaktorbyggnaden runt reaktor nummer 3 i Fukushima Daiichi har exploderat i en vätgasexplosion. Video finns nedan.
Myndigheterna säger att inneslutningen är intakt.