Japanese Earthquake, Tsunami, and Nuclear Reactors

2. Radiation Monitoring

On 28 March, deposition of iodine-131 was detected in 12 prefectures, and deposition of cesium-137 in 9 prefectures. The highest values were observed in the prefecture of Fukushima with 23 000 becquerel per square metre for iodine-131 and 790 becquerel per square metre for caesium-137. In the other prefectures where deposition of iodine-131 was reported, the range was from 1.8 to 280 becquerel per square metre. For caesium-137, the range was from 5.5 to 52 becquerel per square metre. In the Shinjyuku district of Tokyo, the daily deposition of both iodine-131 and cesium-137 was below 50 becquerel per square metre. No significant changes were reported in the 45 prefectures in gamma dose rates compared to yesterday.

As of 28 March information on radioactivity in drinking water collected mainly from the Japanese Ministry of Health, Labour and Welfare indicates that recommendations for restrictions based on I-131 concentration remain in place only in four locations in the prefecture of Fukushima. To date, no recommendations for restrictions have been made based on Cs-137. The Japanese limits for the ingestion of drinking water by infants is 100 becquerel per litre.

Five soil samples, collected at distances between 500 and 1 000 metres from the exhaust stack of Unit 1 and 2 of the Fukushima Nuclear Power Plant on 21 and 22 March, were analysed for plutonium-238 and for the sum of plutonium-239 and plutonium-240. (Due to analytical reasons, the isotopes plutonium-239 and plutonium-240 cannot be measured separately). Plutonium-238 was detected in 2 of the 5 samples, while plutonium-239/240 was detected in all samples as expected.

Concentrations reported for both, plutonium-238 and plutonium-239/240 are similar to those deposited in Japan as a result of the testing of nuclear weapons. The ratio of the concentrations of plutonium-238 and plutonium-239/240 in two of the samples indicate that very small amounts of plutonium might have been released during the Fukushima accident, but this requires to be further clarified.

As far as food contamination is concerned, 63 samples taken from 24 - 29 March, and reported on from 27 - 29 March, for various vegetables, fruit (strawberries), mushrooms, eggs, seafood and pasteurized milk in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Miyagi, Niigata, Tochigi and Yamagata), stated that results for iodine-131, caesium-134 and caesium-137 were either not detected or were below the regulation values set by the Japanese authorities.

The Joint FAO/IAEA Food Safety Assessment Team met with local government authorities in Ibaraki prefecture on Monday and provided advice related to contamination of food and the environment, including the mechanisms and persistence of such contamination, examples of remediation strategies, international standards and sampling plan designs and radionuclide transfer from soil to plants, particularly as related to rice production in the area.

Local government authorities briefed the FAO/IAEA Team on the extent of contamination in Ibaraki, the principle agricultural products affected, the main production areas and production methods (greenhouse, open-air) and levels of contamination found.

The FAO/IAEA team is also meeting with the local authorities in Tochigi prefecture today, and will meet with local government officials in Gunma tomorrow.

Sea Water Samples

No new results from the marine monitoring stations 30 km off-shore were reported for 27 or 28 March. However, new analyses in seawater 330 m east to the discharges point of NPP Units 1 - 4 were made available for 27 March. These concentrations show a significant decrease from 74 000 Becquerel per litre of iodine-131, 12 000 Becquerel per litre of cesium-137, and 12 000 Becquerel per litre of cesium-134 on 26 March to 11 000 Becquerel per litre of iodine-131 and 1 900 Becquerel per litre of cesium-137 on 27 March.

Sea water samples were also collected daily at a location 30 m from the common discharge point for Units 5 - 6. These results also show an increase in the radionuclide concentrations on 26 March. The sea water samples collected on March 27 show as well a decrease of the radionuclide concentration.


It can be expected that the data will be quite variable in the near future depending on the discharge levels. In general, dilutions by ocean currents and into deeper waters as well decay of short lived radionuclides e.g. I-131 or I-132 will soon lead to lower values.

Marine Organisms

First analyses were reported in fish carried out by the National Research Institute of Fishery Research. 5 samples of fish were collected from the port of Choshi (Chiba prefecture) and 4 of 5 samples showed Cs-137 concentrations below limit of detection. In one sample Cs-137 was found with 3 Bq/kg (fresh weight) and it was reported that it was slightly above the limit of detection. This concentration is far below any concern for fish consumption.

It is still too early to draw conclusions for expected concentrations on marine food, because the situation may change rapidly, however, it is expected that the detected initial concentrations of seawater will soon drop to lower values by dilution and the levels in marine food will most likely not reach levels above given limits for consumption, (presuming that discharges of contaminated seawater from the reactor will not continue). It is not expected that fish or other marine food will be collected in a close area to the NPP Fukushima at the present situation. Some marine algae are known to accumulate in particular I-131 and Tc-99m. However, these values will soon be of no concern due to the short half-lives of the radionuclides mentioned.

Modelling Marine Dispersion

The Group SIROCCO of the Observatoire Midi-Pyrenées of the University of Toulouse, CNRS, is continuing to carry out model calculations. The model is based on an ocean circulation and current weather conditions and they results showed an initial north-eastern transport of liquid releases from the damaged reactors and the contaminated water would reach the northern monitored stations between 1 and 2 weeks later.

A model with tracer release directly in the sea show an along shore propagation in the southern direction and a northeast propagation moving away from the coast.

http://www.iaea.org/newscenter/images/dispersion-900.gif


With tracer release from atmospheric deposition, the propagation stretch offshore entering the Kuro-Shivo current in few days.

The first results are shown in Fig. 3 and 4. The data are converted into Bq/L by assuming arbitrary discharge or aerial release activities, respectively. The results should just be taken as indication of the dilution capacity and transport route of sea water.

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Areva: Fukushima Won't Affect Global New Nuclear Build -
First Published Tuesday, 29 March 2011 12:36 pm - © 2011 Dow Jones

PARIS -(Dow Jones)- New builds of nuclear reactors around the world may be delayed to integrate amended safety standards due to the Fukushima accident, but "there is no question outside of Japan to cancel new build programs or stop current constructions," French state-controlled nuclear engineering firm Areva SA (CEI.FR) believes, according to an internal document read by Dow Jones Newswires Tuesday.

In the document, Areva assessed "the potential business impacts on the nuclear industry," gauging the reactions of countries with a nuclear installed base or/and a new build program, noting that most "have had pretty rational reactions" following the accident at the Fukushima plant, operated by Japanese utility Tokyo Electric Power Co. Inc. (9501.TO).
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http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr0933/sec3/082r3.html

The risks of beyond design basis accidents in the spent fuel storage pool were examined in WASH-140016 (App. I, pp. I-96ff). It was concluded that these risks were orders of magnitude below those involving the reactor core. The basic reason for this was the simplicity of the spent fuel storage pool -- the coolant is at atmospheric pressure, the spent fuel is always subcritical and the heat source is low, there is no piping which can drain the pool, and there are no anticipated operational transients that could interrupt cooling or cause criticality.

The reasons for reexamination of spent fuel storage pool accidents were two-fold. First, spent fuel is being stored instead of reprocessed. This has led to the expansion of onsite fuel storage by means of high density storage racks, which results in a larger inventory of fission products in the pool, a greater heat load on the pool cooling system, and less distance between adjacent fuel assemblies. Second, some laboratory studies have provided evidence of the possibility of fire propagation between assemblies in an air-cooled environment.543,544 These two reasons, put together, provided the basis for an accident scenario which was not previously considered.

Safety Significance

A typical spent fuel storage pool with high density storage racks can hold roughly five times the fuel in the core. However, since reloads typically discharge one third of a core, much of the spent fuel stored in the pool will have had considerable decay time. This reduces the radioactive inventory somewhat. More importantly, after roughly three years of storage, spent fuel can be air-cooled, i.e., such fuel need not be submerged to prevent melting. (Submersion is still desirable for shielding and to reduce airborne activity, however.)

If the pool were to be drained of water, the discharged fuel from the previous two refuelings would still be "fresh" enough to melt under decay heat. However, the zircaloy cladding of this fuel could be ignited during the heatup.543 The resulting fire, in a pool equipped with high density storage racks, would probably spread to most or all of the fuel in the pool. The heat of combustion, in combination with decay heat, would certainly release considerable gap activity from the fuel and would probably drive "borderline aged" fuel into a molten condition. Moreover, if the fire becomes oxygen-starved (quite probable for a fire located in the bottom of a pit such as this), the hot zirconium would rob oxygen from the uranium dioxide fuel, forming a liquid mixture of metallic uranium, zirconium, oxidized zirconium, and dissolved uranium dioxide. This would cause a release of fission products from the fuel matrix quite comparable to that of molten fuel.545 In addition, although confined, spent fuel pools are almost always located outside of the primary containment. Thus, release to the atmosphere is more likely than for comparable accidents involving the reactor core]

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Frequency Estimate
BWR spent fuel can be uncovered either by extended loss of pool cooling, which results in boiloff, or by an accident which drains the pool. Both mechanisms were considered

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Ultimately, makeup to the pool could be supplied by bringing in a fire hose (60 gpm would suffice). Although one would expect that the failure probability associated with bringing in a hose (over a period of four or more days) would be very low, it must also be remembered that working next to 385,000 gallons of potentially contaminated boiling water on top of a 10-story building is not a trivial problem. We will assume, based purely on judgment, that the conditional failure probability for this method of makeup is on the order of 5%. When these probabilities are combined, the result is a frequency of 1.4 x 10-6/RY for an accident initiated by loss of spent fuel pool cooling.

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After a seismic event severe enough to breach a seismic Category I spent fuel pool, the probability of RHR failure is higher than that of our previous scenarios. Moreover, the RHR might not be able to supply enough makeup. Finally, the time frame is very short, considering that manual valves must be opened and other earthquake-induced problems may be distracting plant personnel. We will assume that 90% of the time the draining rate will be slow enough to both be within the capacity of RHR makeup and also allow operator diagnosis and the necessary manual lineup of RHR to the pool. We will further assume a 90% probability of RHR remaining operable after the earthquake. This gives a total failure conditional probability of 19%.

Thus, for a site with a high seismic probability, the frequency of earthquake-induced accidents is estimated to be 1.9 x 10-6/RY. Adding the tornado-induced accident frequency to this, we get a frequency for this class of accidents of 2.2 x 10-6/RY.

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dorispulaski said:

Just a question: Are any of you still finding these reports of mine interesting? I'll keep checking on stuff, and reporting, if you do?

And if there are any questions you'd like to ask, either about the situation in Japan, about radiation, reactors, weapons tests or whatever, I'll try to find you an answer.

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TSURUGA —
The Japan Atomic Energy Agency said Friday it will restart the prototype fast-breeder reactor Monju on May 6 after more than 14 years of suspension, after getting the green light Wednesday from local governments.

The reactor, located in Tsuruga, Fukui Prefecture, was suspended in December 1995 due to a sodium coolant leak and a resultant fire there. The resumption has since been postponed several times because of delays in repairs. Although the Monju reactor suffered a temporary glitch in a coolant leakage sensor Monday, the government-affiliated agency said it should be able to clarify the cause.

Unlike regular light-water reactors that run on uranium, this reactor uses an oxide mix of plutonium and uranium and is designed to generate more plutonium than it burns.

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UPDATE AS OF 6:30 P.M. EDT, TUESDAY, MARCH 29:
Tokyo Electric Power Co. said that cooling water is being added to the spent storage fuel pools at reactors 2 and 3. Reactor 2 was using a temporary motor-driven pump and reactor 3 was using a truck to pump the freshwater into the fuel storage pools. The International Atomic Energy Agency (IAEA) said that plans are being made to begin pumping freshwater into the fuel storage pool at reactor 4 starting today.

IAEA said that 63 food samples taken March 24-29 in eight prefectures (Chiba, Fukushima, Gunma, Ibaraki, Miyagi, Niigata, Tochigi and Yamagata) were below regulatory limits set by the Japanese government for iodine-131, cesium-134 and cesium-137.

New analyses of seawater about 1,000 feet from the discharge point of reactors 1 through 4 show "a significant decrease" in radiation levels from March 26, IAEA said.

Readings for iodine-131 went from 2,000,000 picocuries (1 picocurie is one-trillionth of a curie) per liter on March 26 to 297,300 picocuries per liter on March 27. Readings for cesium-137 went from 324,324 picocuries per liter on March 26 to 51,351 picocuries per liter on March 27. IAEA said that radiation readings in seawater "will be quite variable in the near future depending on water discharge levels."

Japan's National Research Institute of Fishery Science has analyzed five fish samples from the port of Choshi in Chiba prefecture and found concentrations in the fish to be "far below any concern for fish consumption." Four of five samples showed cesium-137 concentrations below the limit of detection. In the remaining sample, cesium-137 was found to be slightly above detectable levels.

IAEA said the situation was evolving, but that concentrations of radionuclides in seawater would soon drop to lower values by dilution and that the levels in marine food would most likely not reach levels above regulatory limits set for consumption.

In the United States, the U.S. Environmental Protection Agency's daily data summary from its RadNet radiation air monitors across the United States show typical fluctuations in background radiation levels as of 8:30 A.M. EDT. "The levels detected are far below levels of concern," EPA said

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On approximately 5:56 pm, March 30th 2011, TEPCO employee discovered smoke generation from power panel (*)at the turbine building Unit 1 (Reactor cold shutdown). On 5:57 pm, March 30th 2011, TEPCO immediately reported this incident to the fire department.

Subsequently the fire department consisting of TEPCO employee inspected the area. On approximately 6:13 pm, March 30th 2011,we confirmed the smoke generation stopped after interrupt electrical supply to the power panel.

From now, the fire department will conduct inspection around the area.

TEPCO will also conduct an investigation into a cause in detail. This incident will not cause any effect of radiation externally. (Previously announced on March 30th, 2011)

On 7:15 pm, March 30th 2011, the fire department made a judgmental decision that this incident was caused fault of the power panel, they found no signs of fire.

(*) power panel: power supply board to supply electricity to the motor of a drawing water pump to the outdoor duct.

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Today's work for cooling the spent fuel pools
- From 9:25 am, freshwater injection to Unit 2 was conducted by a temporary motor driven pump. But, because of the malfunction of that pump at 9:45 am, we decided to switch to the fire fighting pump. At 0:30 pm, we switched to use the fire pump. At 0:47 pm and 1:10 pm, because we find tear in a part of hose we prepare to restart freshwater injection.
- At 2:04 pm, we conducted spray water to Unit 4 by a concrete pumping vehicle.

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Today’s NHK news regarding status of Fukushima Daiichi nuclear power station as of 21:00 on March 30
●Kaieda urges safety steps at other nuclear plants
Japan's industry minister has urged power companies across the country to secure emergency energy sources for their nuclear power stations. Banri Kaieda told reporters on Wednesday that the accident at the Fukushima Daiichi plant was due to a failure to secure emergency electricity and a loss of cooling systems at the reactors. Kaieda urged utility companies to secure mobile generators as a source of emergency power that can safely cool nuclear reactors, and to ensure water-supply routes for fire engines. He demanded that the companies confirm emergency steps and conduct drills within a month, or stop operating their nuclear power plants. Kaieda added that putting an immediate end to operations at nuclear power plants is out of the question, because Japan relies on them for about 30 percent of its electricity. NHK has learned that 90 percent of the 15 nuclear power stations nationwide, excluding the 2 quake-hit plants in Fukushima, have decided to introduce new emergency power generators, including mobile generators. Some utilities have already conducted simulations for cooling procedures based on a scenario in which emergency generators have failed to work at their nuclear reactors.
Wednesday, March 30, 2011 16:57 +0900 (JST)


●TEPCO halts work to remove radioactive water
The operator of the troubled Fukushima Daiichi nuclear power plant has suspended work to move highly radioactive water from the basement of the turbine building into the turbine condenser at the No. 1 reactor. Tokyo Electric Power Company suspended the operation on Tuesday morning after the condenser became full of water. The work began on Thursday after water in the basement of the turbine building was found to contain radiation about 10,000 times higher than would normally be found inside an operating nuclear reactor. The Nuclear and Industrial Safety Agency says the water is now about 20 centimeters deep, half the initial level. TEPCO is studying a plan to move water from a tunnel outside the turbine building into an on-site waste disposal facility with a capacity of more than 25,000 tons. The water contains radioactive substances, and its level is only 10 centimeters below the top of the tunnel. TEPCO also planned to move highly radioactive water from the basements of the turbine buildings of the No. 2 and No. 3 reactors into turbine condensers with a capacity of 3,000 tons each. But both condensers turned out to be full. Plant workers are now using pumps that can draw 10 to 25 tons of water per hour to move water from the condensers' storage tanks into other tanks. They then hope to move water inside the condensers into the storage tanks and fill the condensers with the highly radioactive water from the basements.


Wednesday, March 30, 2011 16:37 +0900 (JST)
●Air may be leaking from reactors No. 2 and 3
Japan's Nuclear and Industrial Safety Agency says air may be leaking from the No 2 and No 3 reactors at the Fukushima Daiichi power plant. The agency was responding at a news conference on Wednesday to speculation that low pressure inside the 2 reactors was due to possible damage to the reactors' pressure vessels. It said some of their data show pressure is low, but there is no indication of large cracks or holes in the reactor vessels. The agency said fluctuations in temperature and pressure are highly likely to have weakened valves, pipes and openings under the reactors where the control rods are inserted.Wednesday, March 30, 2011 15:15 +0900 (JST)

●Radioactive elements in No.1 reactor tunnel
Japanese nuclear safety officials say radioactive iodine and cesium have been found in water at the Fukushima Daiichi power plant coming from a tunnel outside the turbine building of the No.1 reactor. The Nuclear and Industrial Safety Agency says the levels of radioactive substances detected are low, at one-to-ten percent of those occurring in an operating nuclear reactor. The agency says the type of radioactive substances found in the water in the tunnel indicates some relation to the contaminated water in the basement of the No.1 reactor turbine building. It says the water in the tunnel will not be released into the sea.
Wednesday, March 30, 2011 12:57 +0900 (JST)
●High radiation levels in waters off Fukushima
The Nuclear and Industrial Safety Agency says radioactive iodine in excess of 3,300 times the national limit was found in seawater near the troubled Fukushima Daiichi nuclear plant on Tuesday afternoon. This was the highest measured in waters off the plant. The level of radioactive iodine-131 found 330 meters south of a water outlet of the plant was 3,355 times regulated standards at 1:55 PM on Tuesday. The outlet is used to drain water from the plant's No. 1 to No. 4 reactors. Radioactive iodine-131 measured 50 meters north of the water outlet of the No. 5 and No. 6 reactors was 1,262 times the regulated standards at 2:10 PM on Tuesday.
This was also the highest reading at this location. An agency official told reporters on Wednesday morning that people in a 20-kilometer radius area from the troubled plant have been ordered to evacuate and the radioactive substance will be significantly diluted in the ocean by the time people consume marine products. The official added that efforts need to be made to prevent the contaminated water from flowing into the sea. Airborne radiation levels continue to decline in most prefectures, including Fukushima and nearby Ibaraki. Municipalities measured the radiation levels between 00:00 AM and 9:00 AM on Wednesday.
Wednesday, March 30, 2011 12:23 +0900 (JST)
●Aerial photos reveal Fukushima plant damage
Aerial photographs of the Fukushima Daiichi nuclear plant show the scope of the devastation caused by tsunami and hydrogen explosions. NHK obtained the high resolution photos taken from an unmanned plane on March 20th and 24th. An aerial survey firm in Niigata Prefecture, Air Photo Service, took them at the request of the plant's operator, Tokyo Electric Power Company. One photo shows a large hole on the roof of the turbine building of the No.3 reactor. It was apparently created when debris hit the roof in a hydrogen explosion. Part of a pipe is missing between the reactor building and an exhaust stack. Heavy oil tanks were swept away from the pier by the tsunami and drifted 150 meters westward, blocking a road for vehicles needed for restoration work. Containers and passenger cars are piled up at the foot of a hill to the west of the No.4 reactor. Another photo shows pump trucks connected by hoses in a line that stretches from the pier to the first four reactors.
Wednesday, March 30, 2011 08:48 +0900 (JST)
●Radiation levels falling in waters off Fukushima
The science ministry says levels of radiation in seawater near the crippled Fukushima Daiichi Nuclear Power Plant are on the decline. The ministry has been collecting seawater samples at 4 locations 30 kilometers off the coast of Fukushima Prefecture since March 23rd. The locations were at intervals of 20 kilometers from north to south. The ministry started the research after waters near the plant's drain outlets were found to be contaminated with a high density of radioactive substances. The ministry said 1.5 to 3.9 becquerels of radioactive cesium-137 per liter were found in seawater samples taken on Sunday. The amounts represent 1,000 to 2,600 times the levels measured in the same area 2 years ago. But the current levels are only one-fifth to one-tenth of those detected on March 23rd. The density of radioactive iodine-131 is also decreasing. It now stands at 5.4 to 15 becquerels per liter. The ministry said radiation density in the seawater is higher than normal, but it is declining.
Cesium-137 is said to remain in the environment for a longer time than other substances as it takes roughly 30 years to lose half of its radioactive intensity. The Marine Ecology Research Institute says cesium-137 will not be directly absorbed into fish through gills but some species can accumulate the element by eating plankton and smaller fish. It's believed that through this process, the density of cesium in fish can increase 10 to 100 times the level in the seawater. It usually takes some time for radioactive material to be detected in fish after it flows into the sea. In many cases, such substances are found in flatfish and Japanese seaperch 2 to 3 months after a confirmed leak into the sea. However, unlike mercury, such elements are eliminated from fish in several weeks.
Wednesday, March 30, 2011 06:25 +0900 (JST)
End

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UPDATE AS OF 12 P.M. EDT, WEDNESDAY, MARCH 30:
Operators of nuclear power stations in Japan have been urged to ensure their facilities have emergency power sources.

Industry Minister Banri Kaieda Wednesday attributed the nuclear emergency in Japan to the loss of cooling systems at the Fukushima Daiichi nuclear power plant, the Japan Atomic Industry Forum reported. He told utility companies they should have mobile generators on hand to cool their nuclear reactors as an added safety measure.

Kaieda said the utilities should confirm the steps they have taken and conduct drills within a month or stop operating their nuclear facilities.

According to the NHK news service, many companies are introducing emergency power generators to their facilities. Some have conducted drills for cooling operations based on a situation in which emergency generators fail.

At the Fukushima Daiichi site, workers continued to inject fresh water into reactors 1, 2 and 3 to keep them cool, while at the same time dealing with water that has pooled in the basements of turbine buildings and in concrete trenches near the units. As available storage space in the reactors' condensers is filled, Tokyo Electric Power Co. is looking to store the radioactive water in tanks that will be brought to the facility. TEPCO has switched to fresh water for spraying the spent fuel pools for reactors 1, 2, 3 and 4.

All the units at Daiichi are operating on off-site electric power and work continues to connect equipment. High radiation levels and wet equipment still hampers restoration of the plants' original machinery.

The U.S. nuclear energy industry will learn important lessons from the Fukushima Daiichi accident and "identify additional steps we can and will take to further improve safety at our nuclear plants," one of the industry's leaders told a U.S. Senate committee today.

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Levis reminded senators not to extrapolate earthquake and tsunami data from one location of the world to another when evaluating natural hazards, emphasizing that the catastrophic events in Japan occurred along a “subduction zone,” the type of tectonic region that produces earthquakes of the largest magnitude. In the continental United States, the only subduction zone lies off the coast of northern California, Oregon and Washington. None of California’s four reactors are located near this subduction zone. The California Coastal Commission last week concluded that a “nuclear emergency such as is occurring in Japan is extremely unlikely at the state’s two operating nuclear power plants,” Levis said.

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IAEA Briefing on Fukushima Nuclear Accident (30 March 2011, 16.30 UTC)
On Wednesday, 30 March 2011, the IAEA provided the following information on the current status of nuclear safety in Japan.
The TV news said that TEPCO was considering spraying the entire site with some kind of fixative to keep dust down. Neither JAIF, TEPCO, IEEA, or NEI have mentioned that.


1. Current Situation
Overall at the Fukushima Daiichi plant, the situation remains very serious.

With respect to the water that is present in the turbine buildings. In Unit 1, water has continued to be pumped into the condenser with 3 pumps (6.5 ton/hour each) and the water level has reduced from 40cm to 20cm. In Unit 2 from 07.45 UTC, pumping of water from the Condensate Storage Tank into the Surge Tank was started so that the that condenser can be drained to the Condensate Storage Tank and contaminated water can be pumped out from the Turbine building into the condenser. The same process of pumping the water from the Condensed Water Storage Tank into the Surge Tank was started on Unit 3 at 08.40 UTCon March 28.

Near the Unit 3 building, 3 workers spilled water over themselves when removing a flange from seawater pipes on the residual heat removal system (RHR). After showering, contamination was not detected.

Fresh water has been continuously injected into the Reactor Pressure Vessel (RPV) through feed-water line at an indicated flow rate of 8.0 m3/h at Unit 1. The pumping of freshwater into the RPV has been switched from fire trucks to temporary electrical pumps with diesel generator. At Units 2 and 3 fresh water is being injected continuously through the fire extinguisher line at an indicated rate of 7 m3/h using a temporary electric pump.

The indicated temperature at the feed water nozzle of the RPV of Unit 1 has decreased from 323 oC to 281 oC and at the bottom of RPV remained stable at 134 oC. There is a corresponding decrease in Drywell pressure. At Unit 2 the indicated temperature at the feed water nozzle of the RPV has increased from 154 oC to 177 oC and at the bottom of RPV has increased from 78 oC to 88 oC. Indicated Drywell pressure remains at atmospheric pressure. For Unit 3 the indicated temperature at the feed water nozzle of the RPV is about 75 oC and at the bottom of RPV is about 116 oC. The validity of the RPV temperature measurement at the feed water nozzle is still under investigation.

With respect to the Spent Fuel Pools. It was planned to commence the pumping of water into the Unit 1 Spent Fuel Pool by concrete pumping truck from 29 March. Also on 29 March pumping of fresh water into the Unit 2 spent fuel pool commenced via a temporary electrical pump. The temperature of the spent fuel pool is 46o C as of 19:00 UTC 29 March. For Unit 4 it was planned to commence pumping freshwater into the spent fuel pool on March 29. The IAEA has not received information on implementation of spraying activities in units 1 and 4.

Units 5 and 6 remain in cold shutdown


2. Radiation Monitoring

The majority of the recently measured radioactivity levels in drinking water are being reported below the levels established by the Japanese authorities which are 100 Bq/L of I-131 for infants; 300 Bq/L for adults and 200 Bq/L of Cs-137 for infants and adults. Previously imposed recommendations for restrictions on drinking water are being lifted in most of the affected locations. As of 28 March, recommendations for restrictions based on I-131 concentration remain in place in one village in the Fukushima prefecture. In three other locations of the Fukushima prefectures, restrictions continue to apply for infants only.

Two IAEA teams are currently monitoring radiation levels and radioactivity in the environment in Japan. On 29 March, one team made gamma dose-rate measurements in the Tokyo region at 8 locations. Gamma-dose rates measured ranged from 0.02 to 0.19 microsievert per hour, which is within or slightly above the background.

The second team made additional measurements at distances of 32 to 62 km, at directions North to Northwest from the Fukushima nuclear power plant. At these locations, the dose rates ranged from 0.5 to 6.8 microsievert per hour. At the same locations, results of beta-gamma contamination measurements ranged from 0.05 to 0.45 Megabecquerel per square metre.

Based on measurements of I-131 and Cs-137 in soil, sampled from 18 to 26 March in 9 municipalities at distances of 25 to 58 km from the Fukushima Nuclear Power Plant, the total deposition of iodine-131 and cesium-137 has been calculated. The results indicate a pronounced spatial variability of the total deposition of iodine-131 and cesium-137. The average total deposition determined at these locations for iodine-131 range from 0.2 to 25 Megabecquerel per square metre and for cesium-137 from 0.02-3.7 Megabecquerel per square metre. The highest values were found in a relatively small area in the Northwest from the Fukushima Nuclear Power Plant. First assessment indicates that one of the IAEA operational criteria for evacuation is exceeded in Iitate village. We advised the counterpart to carefully access the situation. They indicated that they are already assessing.

As far as food contamination is concerned, 35 samples taken from 25-29 March, and reported on 29 March, for various vegetables, fruit (strawberry), seafood, pork and unprocessed raw milk in nine prefectures (Chiba, Gunma, Ibaraki, Kanagawa, Nagano, Niigata, Saitama, Tochigi and Yamagata), stated that results for iodine-131, caesium-134 and caesium-137 were either not detected or were below the regulation values set by the Japanese authorities.

The Joint FAO/IAEA Food Safety Assessment Team met with local government officials in Tochigi prefecture on 29th March and provided advice related to contamination of food and the environment.

Local government officials briefed the FAO/IAEA Team on the extent of contamination in Tochigi, the principle agricultural products affected, the main production areas and production methods (greenhouses, open-air), levels of contamination found (principally in air, tap/ground water and vegetables) and imminent plans to monitor soil contamination. A field visit also took place to a spinach producer outside Utsanomiya City.

Based on these latest discussions with the Tochigi authorities, it is apparent that the focus of the Joint FAO/IAEA mission has changed to some extent from the mechanisms of contamination to remediation strategies and techniques related to plant and animal production, food traceability and water/soil characterization.

The FAO/IAEA team is also meeting with the local government officials in Gunma prefecture today.

No new results from the marine monitoring stations 30 km off-shore as well as from close to the discharge, were reported since 27 March.

One IAEA staff member of the Monaco marine laboratory will fly to Japan on 31 March in order to join the Japanese team assessing marine environment.

The IAEA continues activities under the Joint Radiation Emergency Management Plan of the International Organisations through regular video/teleconferences. As of March 30 the WHO liaison officer is working in the IEC.

In response to the request for data on measurement, the IEC has received information from Singapore. The Singapore Authorities have sent reports on measurements in food imported from Japan (cabbages). Some samples were over the Codex Alimentarius values recommended for international trade. In Singapore no increase in gamma dose rates have been observed and no fission products have been found in air samples.

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Edition:U.S.

Reuters
March 30th, 2010

11:35am EDT
By Sybille de la Hamaide and Mathilde Cru

PARIS | Wed Mar 30, 2011 10:19am EDT

PARIS (Reuters) - Areva Chief Executive Anne Lauvergeon arrived in Japan on Wednesday, broadening out a French delegation that has flown out to help Tokyo Electric Power bring its crippled Fukushima nuclear plant under control.

The head of the French nuclear reactor maker -- one of France's most powerful female executives -- traveled to Tokyo with three French experts in radioactive water contamination.

Two other Areva experts flew to Japan on Tuesday, after a request for help from Tokyo Electric Power (TEPCO), an Areva spokeswoman said.

Separately, President Nicolas Sarkozy will make a flying visit to Tokyo on Thursday, the first foreign leader to arrive since a March 11 earthquake and tsunami killed more than 28,000 people and set off the world's worst atomic crisis in years.

"At the moment the problem which worries TEPCO is water, so we are trying to see -- because they are specialists in the treatment of radioactive waste -- what they could advocate," she said. "They are looking at what aid we could bring them."

While Sarkozy will offer France's support to the Japanese people, Lauvergeon's experience makes her well-placed to help with technical aspects of the crisis. "She knows Japan well, she knows the industry well, it is a way to answer the Japanese request for expertise," the Areva spokeswoman said.
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The French experts will be based in the Tokyo area, where TEPCPO has offices, and not at the nuclear site itself.

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