Status of quake-stricken reactors at Fukushima nuclear power plants
TOKYO, March 19, Kyodo
Michele Kearney's Nuclear Wire - Major Energy and Environmental News and Commentary affecting the Nuclear Industry. Nuclear Activities
Saturday, March 19, 2011
Official ASME Statement on Events in Japan
Subject: Official ASME Statement on Events in Japan
I’d like to share the official ASME statement on Japan that we will be releasing later today.
On behalf of our members, volunteers and staff worldwide, ASME expresses its heartfelt sympathies and concerns to all those affected by the historic earthquake and tsunami causing major widespread damage in Japan, and the unfolding events at the Fukushima Daiichi nuclear power station. This disaster is truly unprecedented in its scope and nature, particularly to Japan’s transportation and energy infrastructure, including nuclear power, thermal power, hydro power, electric transmission, oil refining and beyond. ASME will be monitoring events as they continue to emerge and will be collaborating with our colleagues in Japan and elsewhere to understand the dimensions of these tragic events. We are deeply saddened by the loss of life and the scale of destruction, and we want to acknowledge the valiant and selfless efforts being made by our engineering colleagues in Japan to ensure public safety, along with the many other workers and officials who are heroically responding to this tragedy. Our thoughts and prayers are with the Japanese people at this difficult time.
Your collective efforts on behalf of ASME during this time are greatly appreciated.
Bob Simmons,
ASME President
Friday, March 18, 2011
JAIF HIgh Level Timeline and Sequence of Events
Here is the initial high level timeline and sequence of events from JAIF
THE NUCLEAR COMMUNICATIONS NETWORK Japan Update / Brief No 72 / 18 March 2011
THE NUCLEAR COMMUNICATIONS NETWORK
Japan Update / Brief No 72 / 18 March 2011
Radiation Levels Above Normal, But Falling, Say Authorities
18 Mar (NucNet): Radiation levels on the site and at the site boundary of the Fukushima-Daiichi nuclear power plant in Japan are slowly falling, but are still far above normal levels, according to figures from Tokyo Electric Power Company (Tepco) and Japan’s Nuclear and Industrial Safety Agency (NISA).
At a monitoring post near one of the gates, readings have fallen from 310 microsieverts per hour (microSv/hr) yesterday to 264 microSv/hr (at 12:00 Japan time on 18 March), they said.
Readings from a mobile monitoring post on the plant site have not been updated today, but final readings from yesterday (17 March) at 20:00 Japan time showed 3,600 microSv/hr.
In most countries, the natural background radiation level is in the range of 0.2 to 0.5 microSv/hr, including the natural radon background radiation in buildings.
Unit Status: 18 March 06:00 Japan Time
Unit 1: Cooling with seawater continues.
Unit 2: Cooling with seawater continues. White smoke has been discharged from the reactor building, where damage is suspected to the containment vessel. The cause of the smoke has not been confirmed.
Unit 3: Cooling with seawater continues. After dropping water four times from helicopters yesterday, five tanks of water have been injected from the ground to the spent fuel pool sector using a water-cannon truck. The results are being evaluated.
Unit 4: Work continues to stabilise the reactor, which was shut down at the time of the earthquake and has no fuel in it. Work also continues to stabilise the spent fuel pool, which is almost full of spent fuel. The plan is to fill this pool with cooling water from water cannon and from the unit’s normal pumps as soon as power is re-established onsite. The International Atomic Energy Agency (IAEA) said the temperature of the spent fuel at unit 4 was 84 degrees Celsius on 14 March at 04:08 Japan time.
There are no newer readings.
Units 5 and 6: The status of these reactors and of their fuel pools remains stable as long as the emergency power diesel engine for unit 6 – the only one that is working – remains operational and supplies power to the pool cooling system and essential water cooling components. Tepco said it hopes the situation can be improved with restoration of the plant’s main external power supply. The IAEA said the temperature of the fuel in the unit 5 fuel pool was 65.5 degrees Celsius at 03:00 Japan time on 18 March.
At unit 6 it was 62 degrees Celsius.
External power supply: A connection has been laid from the Tohoku high-voltage line to the site and at 06:30 Japan time today it was being checked. Final connection must wait until water injection can be interrupted. The IAEA said engineers had also begun to lay an external grid power line cable to unit 2 at the plant. The operation was continuing as of 05:30 Japan time. They plan to reconnect power to unit 2 once the spraying of water on the unit 3 reactor building is completed.
The latest status update from the Japan Atomic Industrial Forum is
online:
>>Related reports in the NucNet database (available to subscribers)
THE NUCLEAR COMMUNICATIONS NETWORK
Japan Update / Brief No. 73 / 18 March 2011
Fukushima-Daiichi Events Provisionally Rated INES Level 5
18 Mar (NucNet): The reactor core damage and loss of all cooling function at units 3 and 4 of the Fukushima-Daiichi nuclear power plant, and the abnormal rise of radiation dose rates at the plant site boundary due to releases by unit 1 following an earthquake and tsunami on 11 March 2011, have been provisionally rated at Level 5 on the International Atomic Energy Agency’s International Nuclear and Radiological Event Scale (INES).*
Level 5 on the scale means an “accident with wider consequences”.
The event at unit 4, where there was loss of coolant to the spent fuel pool, has provisionally been rated as Level 3, which means “serious incident”.
Incidents at units 1, 2 and 4 of the Fukushima-Daini nuclear plant have provisionally been rated as Level 3.
In a report to the IAEA on units 1, 2 and 3 at Fukushima-Daiichi, Japan’s Nuclear and Industrial Safety Agency (NISA) said electricity rooms and seawater pump rooms were flooded when the tsunami struck, and the only cooling function available was from a turbine driven pump.
The operation of this pump increased the pressure in the reactor’s suppression chamber and the pump had to be stopped. This resulted in the loss of all cooling function and the declaration of a state of emergency, the report says.
In an effort to cool units 1, 2, and 3, seawater was injected into the reactor vessels using fire pumps. The gas in the containment vessels was also vented. When venting the containments, the radiation dose rate at the boundary level of the site exceeded the limit of 0.5 millisievert per hour, and for this reason the initial Level 4 classification for unit 1 was revised upwards.
The report says the explosions at the reactors on 12 to 14 March were believed to have been caused by hydrogen gas.
It adds that the behaviour of the pressure of the reactor vessel and the containment vessel, and the behaviour of the rector vessel’s water level, were “complicated” and some measurements could not be taken because of failures of measurement equipment.
* The International Nuclear and Radiological Event Scale
The International Nuclear and Radiological Event Scale (INES) was developed by the IAEA and the OECD in 1990 to better communicate and standardise the reporting of nuclear incidents or accidents to the public.
Events are classified on the scale at seven levels: Levels 1–3 are called “incidents” and Levels 4–7 “accidents”. The scale is designed so that the severity of an event is about 10 times greater for each increase in level on the scale. Events without safety significance are called “deviations”
and are classified Below Scale / Level 0.
Chernobyl rated as 7 (Major Accident) on the scale and Three Mile Island rated 5 (Accident with Wider Consequences).
7 Major Accident
6 Serious Accident
5 Accident With Wider Consequences
4 Accident with Local Consequences
3 Serious Incident
2 Incident
1 Anomaly
0 Below Scale/No Safety Significance
US deploying unmanned high-altitude reconnaissance to check status of spent-fuel pool in Fukushima 4
Status of Fukushima power plant
The Federation of Electric Power Companies of Japan (FEPC) Washington DC Office
As of 10:15AM (EST), March 17, 2011
Radiation Levels
o At 9:20AM (JST) on March 17, radiation level at elevation of 1,000ft above Fukushima Daiichi Nuclear Power Station: 4,130 micro sievert.Fukushima Daiichi Unit 1 reactor
o At 9:20AM on March 17, radiation level at elevation of 300ft above Fukushima Daiichi Nuclear Power Station: 87,700 micro sievert.
o At 11:10AM on March 17, radiation level at main gate (approximately 3,281 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 646.2 micro sievert.
o At 7:50PM on March 17, radiation level outside main office building (approximately 1,640 feet from Unit 2 reactor building) of Fukushima Daiichi Nuclear Power Station: 3,599 micro sievert.
o For comparison, a human receives 2,400 micro sievert per year from natural radiation in the form of sunlight, radon, and other sources. One chest CT scan generates 6,900 micro sievert per scan.
o Since 10:30AM on March 14, the pressure within the primary containment vessel cannot be measured.Fukushima Daiichi Unit 2 reactor
o At 12:50PM on March 17, pressure inside the reactor core: 0.185MPa.
o At 12:50PM on March 17, water level inside the reactor core: 1.7 meters below the top of the fuel rods.
o At 12:25PM on March 16, pressure inside the primary containment vessel: 0.40MPaabs.Fukushima Daiichi Unit 3 reactor
o At 12:50PM on March 17, pressure inside the reactor core: -0.027MPa.
o At 12:50PM on March 17, water level inside the reactor core: 1.8 meters below the top of the fuel rods.
o At 12:40PM on March 16, pressure inside the primary containment vessel: 0.23MPaabs.Fukushima Daiichi Unit 5 reactor
o At 6:15AM on March 17, pressure inside the suppression chamber was observed to fluctuate.
o At 7:00AM on March 17, pressure inside the suppression chamber: 0.22MPa.
o At 7:05AM on March 17, pressure inside the suppression chamber: 0.44MPa.
o At 7:10AM on March 17, pressure inside the suppression chamber: 0.26MPa.
o At 7:15AM on March 17, pressure inside the suppression chamber: 0.52MPa.
o At 7:20AM on March 17, pressure inside the suppression chamber: 0.13MPa.
o At 7:25AM on March 17, pressure inside the suppression chamber: 0.57MPa.
o At 9:48AM on March 17, a Self Defense Forces helicopter made four water drops aimed for the spent fuel pool.
o At 4:35PM on March 17, pressure inside the reactor core: 0.005MPa.
o At 4:35PM on March 17, water level inside the reactor core: 1.95 meters below the top of the fuel rods.
o At 7:05PM on March 17, a police water cannon began to shoot water aimed at the spent fuel pool until 7:22PM.
o At 7:35PM on March 17, five Self Defense Forces emergency fire vehicles shot water aimed at the spent fuel pool, until 8:09PM.
o At 2:00PM on March 16, the temperature of the spent fuel pool was measured at 145 degrees Fahrenheit.
Fukushima Daiichi Unit 6 reactor
o At 2:00PM on March 16, the temperature of the spent fuel pool was measured at 140 degrees Fahrenheit.
Fukushima worst case scenario from an ex-Sandia Engineer - Other experts disagree about worst case from this point
Fukushima worst case scenario from an ex-Sandia Engineer - Other experts disagree about worst case from this point
Dr Michael Allen describes how a Fukushima worst case scenario could develop. He is an ex-Sandia Engineer. Other experts disagree about worst case from this point. Also, these scenarios are avoided with fresh water in the reactors and on the spent fuel ponds.Dr. Michael Allen, vice provost for research and dean of graduate studies at Middle Tennessee State University, spent much of his early career at Sandia National Labs studying nuclear reactor accidents of the worst kind and performing simulations to better understand how bad things happen -- including core meltdowns.
Allen wouldn't say if he thinks the crisis in Japan will become the worst nuclear accident in history or whether he believes a full-scale meltdown is inevitable, although he described how it could happen. The situation, he said, is far from over.
"I'm concerned about Japan because I think this is a really bad accident and concerned about their people, their infrastructure," Allen said today in a telephone interview. "I don't think this is an accident that is going to go away anytime soon."
Allen has been at MTSU since 2007, but earlier in his career he worked more than 14 years at Sandia National Laboratories in New Mexico, where -- among other assignments -- he headed the federal lab's work on "severe accident phenomenology." That work included using a research reactor to actually melt the core of another reactor to better assess how the core relocates in an accident, as well as the release of fission products. He also conducted hydrogen and steam explosions at desert test sites outside Albuquerque, using reactor fuel simulants to assess the results.
Much of his research directly addressed accident scenarios in which the nuclear fuel is no longer submerged in water, a situation that Japanese workers have been battling for days at the Daiichi reactor complex.
Allen agrees with reports that explosions caused by a hydrogen buildup likely blew the roof off the outer containment buildings at least two of the reactor sites, exposing pools that store highly radioactive spent nuclear fuel rods to the environment. But, based on reports he's heard or read, he thinks the explosion that occurred March 14 at the Daiichi Unit 2 reactor was a steam explosion inside the reactor pressure vessel that probably occurred when part of the exposed fuel core melted and allowed some of the liquefied fuel or super-hot fragments to drop into the water below.
"When that happens, you're going to have a massive steam explosion, which creates extremely high pressure in the reactor pressure vessel," Allen said. As has been noted in various news reports, the pressure dropped inside the reactor and radiation levels outside the unit rose significantly at about that time. That, he said, would seem to support conjecture that the vessel protecting the nuclear core may have been damaged or possibly ruptured and released some of the radioactive constituents.
"I've done many of these experiments," he said. "When you drop a molten core into water, there's a big explosion."
The worst of the worst could come if Japan can't come up with a way to sufficiently cool down the reactor fuel cores. That has reportedly become increasingly difficult with workers evacuating the sites -- at least temporarily -- because of high radiation fields.
"These things play out over a long period of time, longer than people would think," Allen said. "You have an earthquake that lasts maybe a minute, a tsunami that lasts maybe 15 minutes. But these things could go on for months. You could lose all six of the reactors."
If workers are unable to get additional cooling water into the reactor vessel, the molten fuel core will collapse into the water in bottom of the vessel. Eventually the heat from the decaying fuel would boil away the water that's left, leaving the core sitting on the vessel's lower head made of steel.
Should that happen, "It'll melt through it like butter," Allen said.
That, in turn, would cause a "high-pressure melt injection" into the water-filled concrete cavity below the reactor. Because the concrete would likely be unheated, the reaction created by the sudden injection of the reactor's ultra-hot content would be immense, he said.
"It'll be like somebody dropped a bomb, and there'll be a big cloud of very, very radioactive material above the ground," Allen said, noting that it would contain uranium and plutonium, as well as the fission products.
Should these events happen, the best outcome would be if the winds are blowing east and push the radioactive plume over the Pacific Ocean, he said. "It (the radioactivity) will fall out in the ocean and everything will be fine," he said.
The worst case, Allen said, would be if winds pushed a radioactive cloud south toward Tokyo and Japan's highly populated cities. If that were to happen, he said, the consequences would likely be greater than the 1986 accident at Chernobyl, where an entire area of Ukraine had to be evacuated because of the radioactive conditions that increased the risk of developing cancer.
Electrical Power cable progress at Fukushima Daiichi Unit 2 and one diesel units is working again
IAEA - Japanese authorities have informed the IAEA that engineers were able to lay an external grid power line cable to unit 2. The operation was completed at 08:30 UTC. It is now 6:30 PM UTC (14:30 UTC)
The spraying of water on the unit 3 reactor building was temporarily stopped at 11:09 UTC (20:09 local time) of 17 March.
World Nuclear News - The power cable was to be connected when radiation levels had died down after a planned venting operation at unit 2.
In addition, one of the emergency diesel units can now be operated and will be used to supply unit 5 and 6 alternately to inject water to their used fuel pools. Later, the power will be used to top up water in the reactor vessels.
Casualties among power plant workers
* Two Tepco employees have minor injuries.
* Two contractors were injured when the quake struck and were taken to hospital, one suffering two broken legs.
* A Tepco worker was taken to hospital after collapsing and experiencing chest pains.
* A subcontract worker at an "important earthquake-proof building" was found unconscious and was taken to hospital.
* Two Tepco workers felt ill whilst working in the control rooms of Fukushima Daiichi units 1 and 2 and were taken to the medical centre at Fukushima Daini.
* Four workers were injured in the hydrogen explosion at Fukushima Daiichi 1. They were all taken to hospital.
* Eleven workers (four Tepco workers, three subcontract workers and four members of Self Defence Force) were hurt following a similar explosion at Fukushima Daiichi 3. They were transferred to the Fukushima Daini plant. One of the Tepco employees, complaining of pain in his side, was later transferred to hospital.
* The whereabouts of two Tepco workers, who had been in the turbine building of Fukushima Daiichi unit 4, is unknown.
* Only one casualty has been reported at the Fukushima Daini plant. A worker in the crane operating console of the exhaust stack was seriously injured when the earthquake struck. He subsequently died.
Contamination cases
* One Tepco worker working within the reactor building of Fukushima Daiichi unit 3 during "vent work" was taken to hospital after receiving radiation exposure exceeding 100 mSv, a level deemed acceptable in emergency situations by some national nuclear safety regulators.
* Nine Tepco employees and eight subcontractors suffered facial exposure to low levels of radiation. They did not require hospital treatment.
* Two policemen were decontaminated after beng exposed to radiation.
* An unspecified number of firemen who were exposed to radiation are under investigation.
Obama says it is unlikely that radiation will harm anyone in USA and update on Fukushima from NEI and BraveNewClimate
It is unlikely that radiation released from the nuclear reactors in Japan will harm anyone in the United States, President Obama said in a press briefing this afternoon.
Japan's Nuclear and Industrial Safety Agency reported on Thursday that the backup diesel generator for reactor 6 is working and supplying electricity to reactors 5 and 6. TEPCO is preparing to add water to the storage pools that house used nuclear fuel rods at those two reactors.
UPDATE AS OF 1:30 P.M. EDT, THURSDAY, MARCH 17
Radiation readings at the Fukushima Daiichi site boundary were measured today at a lower level, between 2 and 3 millirem per hour.
Brave New Climate analysis from Barry Brook
Are the spent fuel in the pools in Units 3 and 4 are now uncovered? The big concern here is that unlike the releases from damaged fuel in the reactor cores of Units 1, 2, and 3, which were largely filtered by scrubbing in the containment suppression pools (wetwell torus), releases of volatile fission products (e.g., cesium and iodine) from these spent fuel pools have direct pathways to the environment, if they remain dry for an extended period.
Efforts to deliver water to these pools have proven to be very difficult, and fuel damage may be occurring. If they are exposed, then the use of the evaporation of salt water as a heat sink over periods of more than a few days is not viable because the quantities of salt deposited as the water evaporates becomes large in volume and plugs the flow paths through the fuel, degrading heat removal. Everything that is cooled becomes a heat sink to condense anything volatilized. Unfortunately, a fresh water supply seems difficult to come by.
In sum, this accident is now significantly more severe than Three Mile Island in 1979. It resulted from a unique combination of failures to plant systems caused by the tsunami, and the broad destruction of infrastructure for water and electricity supply which would normally be reestablished within a day or two following a reactor accident. My initial estimates of the extent of the problem, on March 12, did not anticipate the cascading problems that arose from the extended loss of externally sourced AC power to the site, and my prediction that ‘there is no credible risk of a serious accident‘ has been proven quite wrong as a result. It remains to be seen whether my forecast on the possibility of containment breaches and the very low level of danger to the public as a result of this tragic chain of circumstances will be proven correct. For the sake of the people there, I sure hope it does stand the test of time.
So it is now generally agreed that this is an International nuclear and radiological event scale 6 event. Worse than Three mile island (5) but not yet to Chernobyl (7).
Greater Danger Lies in Spent Fuel Than in Reactors
Radiation Spread Seen; Frantic Repairs Go On
Fukushima March 18 evening update, Barry Brook on the future of nuclear energy
The following is not a significant new update on the situation at Fukushima (see here for the 18 March morning update), because so little information has emerged since my last update this morning. But there is some new information.Below I summarise what news and data I've gathered today, and then provide a 25 minute video of me, recorded just a few days ago, talking about the potential impact of the Fukushima Nuclear Accident on the future of nuclear power deployment, and the prospects of new technologies.
First to Fukushima News. Here is what I've gathered so far today:
1. There have been no new updates from World Nuclear News or NEI updates. The IAEA provided an 'update' on Temperature of Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant, which didn't really say anything new. The latest TEPCO news release doesn't add much.
2. NHK news shows some footage of the fire trucks of the self defence forces and Tokyo fire department (including some borrowed trucks from the locally deployed US military), in the act of hosing down units 3 and 4 with the aim of raising the water levels in the open-topped spent fuel storage ponds (see here for more details) -- they are doing this in serial rather than parallel, due to the difficulty in site access because of debris. They think this will be just as effective anyway. There was clearly steam rising as a result of this addition of some 50 tonnes of water, and a measured drop in on-site radioactivity as a result, so it does seem to be having some effect. I can't say much more than this.
3. The external power line is now stretched to the site and they hope to have AC power connected by early Saturday (JST). The goal is to allow operators to restart Emergency Core Cooling System and Residual Heat Removal pumps for the reactor. TEPCO continues to install cables, transformers and distribution equipment to restore offsite grid power to Fukushima Daiichi reactors 1 and 2. Reactor 1 has now been included in the power restoration plan. Radiation around the reactor buildings are still around 20 mSv/hr, which although much lower than previously, is still hampering operations.
4. Kyodo News reports the following (extract)
The Tokyo Fire Department is slated to join in the operation at the Fukushima plant with 30 trucks capable of discharging massive amounts of water to high places and some 140 firefighters of its ''hyper rescue'' team, who are specialists in rescue operations in large-scale disasters.Read more of this post
But a Tokyo police water cannon truck, whose contribution Thursday was revised Friday to 44 tons from the initially reported 4 tons, and the SDF choppers were not mobilized Friday.
Radiation readings at the troubled nuclear plant have consistently followed a downward path through Friday morning, according to data taken roughly 1 kilometer west of the plant's No. 2 reactor, but plant operator Tokyo Electric Power Co. stopped short of calling the move a trend.
The radiation level at 11 a.m. dropped to 265.0 microsievert per hour from 351.4 microsievert per hour at 12:30 a.m. Thursday. It measured 292.2 microsievert per hour at 8:40 p.m. Thursday, shortly after SDF trucks sprayed water at the No. 3 reactor pool as part of efforts to avert any massive emission of radioactive materials into the air from the facility.
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