Japanese Nuclear Crisis Situation

Update, 23-Apr-2011, 1800 UTC

30 Fukushima workers have now received radiation dosage exceeding 100 millisieverts.

A small piece of concrete, about 1 foot x 1 foot x 2 inches, has been found that is emitting 900 millisieverts per hour of radiation (that level is extremely dangerous to one’s health). It was found during cleanup operations of the exploded debris from Building No. 3. (no doubt there are more…)

140 tons of water was injected into the fuel rod storage pool of No.4 on Saturday as the water temperature remained above 90 degrees Celsius, much higher than normal. (10 more degrees and we have highly radioactive steam entering the world once again)

There are fears that the weight of the water might be further damaging the No. 4 reactor building. The company (TEPCO) says it will be more cautious about the volume of cooling water it injects. It promised to monitor the level and temperature of the water in the pool. (insert sarcasm: that’s reassuring…)

The Japanese government has expressed concern about the structural strength of the No. 1 reactor, saying water injections to cool fuel rods may be making the vessel less earthquake-resistant. (there has been more and more talk of this – sounds like the ‘officials’ are posturing themselves prior to a possible structural collapse in the future)

‘Experts’ have pointed out that since reactors weren’t designed to be filled up with water, the process could put strain on structures and possibly cause cracks, especially if the area were hit by another major tremor as aftershocks continue to rumble around Japan. (makes sense to me…)

Ram, have you been seeing any significant updates? IAEA hasn't even made a major update since the 21st.

No dude, i will check out today.

Edit: Updated.

Updated 4 pm, Monday, April 25, 2011. Japan government establishes unconscionable permissible radiation levels for schoolchildren: take action to overturn this. Unit 4 fuel pool heating up; concern growing about structural integrity of buildings faced with huge water weights.

April 22, 2011. Protests, rallies and other actions slated to occur in at least 16 18 states to commemorate 25th anniversary of Chernobyl catastrophe as well as ongoing Fukushima disaster.


Update, 24-Apr-2011, 1700 UTC

TEPCO has created a map of radiation levels at and around the plant as part of its removal of radioactive debris. It indicates the number of millisieverts per hour at each location.

The company says it will try to complete the clean-up work by July, but hasn’t decided on places and methods of disposing of removed debris yet.

They have decided to construct temporary storage tanks for highly radioactive waste-water that has accumulated. The radioactive water will be sorted into 3 levels of contamination – low, medium and high – and will be stored accordingly.

At the Number 4 reactor, they injected 200 tons of water on Friday and 140 tons of water on Saturday into the reactor’s storage pool for spent fuel rods as the water temperature remained above 90 degrees Celsius, much higher than normal. But there are fears that the weight of the water might be further damaging the No. 4 reactor building.



Update, 25-Apr-2011, 1600 UTC

There are 1,535 fuel rods stored in the No. 4 fuel pool, the most in the entire facility. The temperature has risen precariously close to boiling while a balancing act of water injection versus weight and structural integrity continues. They had backed off on new daily water to 70 tons (17,500 gallons) but the temperature quickly rose to within several degrees of boiling. 210 tons (52,500 gallons) will be injected Monday in an attempt to cool it down.

The no-go evacuation zone (20 km) according to NHK has more than 370 livestock farms containing 4,000 cattle, 30,000 pigs, 630,000 chickens and 100 horses. Many of these animals have died or are facing starvation since their owners evacuated. Fukushima Prefecture has launched an operation to euthanize the weakened animals, return those grazing outside to barns, and disinfect the carcasses of the dead ones.

Japan’s Tokyo Electric Power Company (TEPCO) said it would halve the total compensation of its president, chairman and other top executives as it grapples with the world’s worst nuclear crisis in 25 years at its Fukushima Daiichi plant. (Too bad this type of reprimand doesn’t happen in the U.S. where the execs and banksters compensation continues to soar amid the enormous taxpayer bailouts and government protections)

Update, 26-Apr-2011, 1700 UTC

Robots checking for suspected leaks in No.1 before attempts are made to further flood Reactor No. 1 with more water than before, in an attempt to cool it further.

News regarding this event is becoming very scarce – nothing new.

Nobody ever remembers how close Daiichi is to Daini. If Daiichi goes down it's taking the other complex with it.

IAEA Briefing on Fukushima Nuclear Accident (26 April 2011, 18:00 UTC)

Presentation:
→ Summary of Reactor Status

1. Current situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious, but there are signs of recovery in some functions, such as electrical power and instrumentation.

After the announcement on 11 April by the Government of Japan to establish 'planned evacuation zones' and 'emergency evacuation preparation zones', in a press conference on 22 April by the chief cabinet secretary of Japan Mr. Edano it was stated that "the Prime Minister, as head of the Nuclear Emergency Response Headquarters, has issued instructions to the governor of Fukushima Prefecture and the heads of municipal governments concerned." These instructions included:

* Designation of 'planned evacuation zones' to be applied to some specific zones outside the 20 km radius from the Fukushima Dai-ichi plant: "the villages of Katsurao, Namie and Iitate, part of the town of Kawamata, and part of the city of Minamisoma", where planned evacuations are expected to be implemented in approximately one month's time.
* Designation of 'emergency evacuation preparation zones', to be applied to the area within a 20-30 km radius from the Fukushima Dai-ichi plant (except for areas designated as planned evacuation zones): "the towns of Hirono and Naraha, the village of Kawauchi, and parts of the cities of Tamura and Minamisoma", in which preparations should be made so that the residents can take shelter indoors or can evacuate by their own means in the event of an emergency. In addition, with regard to the areas located within a 20-30 km radius from the nuclear power plant, the advisory for sheltering indoors that has been in effect to date has been lifted.

Changes to Fukushima Daiichi plant status

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA). Additional detail is provided in the IAEA Incident and Emergency Centre (IEC) status summary with information received by 07:00 UTC on 26 April 2011.

Management of on-site contaminated water

According to the 25 April evaluation by NISA of the report submitted by TEPCO, there is a little less than 70,000 tonnes of stagnant water with high level radioactivity in the basement of the turbine buildings of Units 1, 2 and 3.

Plant status

On 25 April the power supply for the temporary electrical pumps that supply water to the reactor pressure vessel of Units 1, 2 and 3 was switched from the off-site power supply to temporary diesel generators to allow work to enhance the off-site supply.

White smoke continues to be emitted from Units 2, 3 and 4.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power.

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

In Unit 4 140 tonnes of fresh water was sprayed over the spent fuel pool on 23 April and 165 tonnes of fresh water was sprayed over the spent fuel pool on 24 April using a concrete pump truck. The nuclear emergency response headquarters reported that temperature measurements showed the spent fuel pool temperature to be 83 °C before spraying and 66 °C after spraying on 23 April, and the spent fuel pool temperature to be 86 °C before spraying and 81 °C after spraying on 24 April.

Nitrogen gas is being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion in the containment vessel. The pressure in the reactor pressure vessel is increasing.

The reactor pressure vessel temperatures in Unit 1 remain above cold shutdown conditions. The indicated temperature at the feedwater nozzle of the reactor pressure vessel is 138 °C and at the bottom of reactor pressure vessel is 111 °C.

The reactor pressure vessel temperatures in Unit 2 remain above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 123 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure. Fresh water injection (approximately 38 tonnes) to the spent fuel pool via the spent fuel pool cooling line was carried out on 25 April.

The temperature at the bottom of the reactor pressure vessel in Unit 3 remains above cold shutdown conditions. The indicated temperature at the feed water nozzle of the reactor pressure vessel is 75 °C and at the bottom of the reactor pressure vessel is 111 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

There has been no change in the status in Unit 5 or Unit 6 or in the common spent fuel storage facility.

2. Radiation monitoring

For the period 21-25 April deposition of I-131 was detected in eight prefectures, ranging from 2.2 to 37 Bq/m2. Deposition of Cs-137 was detected in 11 prefectures, the values reported ranging from 1.3 to 69 Bq/m2.

Gamma dose rates are measured daily in all 47 prefectures. For Fukushima prefecture gamma dose rates decreased from 1.9 μSv/h on 21 April to 1.7 μSv/h on 23 April. In Ibaraki prefecture, gamma dose rates were 0.12 μSv/h. In all other prefectures, reported gamma dose rates were below 0.1 μSv/h with similar decreasing trends.

Gamma dose rates reported specifically for the eastern part of Fukushima prefecture, for distances beyond 30 km from Fukushima Dai-ichi, showed a similar general decreasing tendency, ranging from 0.1 to 19.4 μSv/h on 25 April. The latest maximum reported value for 20 April was 24 μSv/h.

The other 45 prefectures presented gamma dose rates of below 0.1 μSv/h, falling within the local natural background range.

In drinking water, I-131 or Cs-137 is detectable, but in only a few prefectures. As of 1 April, the one remaining restriction on the consumption of drinking water relating to I-131 (at a level of 100 Bq/L) applies to only one village in the Fukushima prefecture, and the restriction applies only to infants.

Food monitoring

Food monitoring data were reported by the Japanese Ministry of Health, Labour and Welfare on 21 April for a total of 62 samples taken over 18-21 April from 11 prefectures (Chiba, Fukushima, Gunma, Ibaraki, Kanagawa, Nagano, Niigata, Saitama, Tochigi, Tokyo and Yamagata). Analytical results for all of the samples of various vegetables, mushrooms, seafood and unprocessed raw milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities.

Food monitoring data were reported by the Japanese Ministry of Health, Labour and Welfare on 22, 23 and 24 April for a total of 164 samples taken in the period 19-23 April from 11 prefectures (Chiba, Fukushima, Gifu, Gunma, Hyogo, Ibaraki, Kanagawa, Niigata, Saitama, Tochigi and Yamagata). Analytical results for 158 of the 164 samples of various vegetables, mushrooms, fruit (strawberry), seafood and raw unprocessed milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities. Six samples of shiitake mushrooms (grown outdoors) taken in Fukushima prefecture on 21 April were above the regulation values set by the Japanese authorities for Cs-134/Cs-137.

Food monitoring data were reported by the Japanese Ministry of Health, Labour and Welfare on 25 April for a total of 15 samples taken on 21 and 24-25 April from seven prefectures (Fukushima, Gunma, Ibaraki, Kanagawa, Niigata, Tochigi and Yamagata). Analytical results for all of the samples of various vegetables, fruit (strawberry), beef, milk and raw unprocessed milk indicated that I-131, Cs-134 and Cs-137 were either not detected or were below the regulation values set by the Japanese authorities.

Food restrictions

On 21 April restrictions on the distribution of raw unprocessed milk produced in Soma City and Shinchi town in Fukushima prefecture were lifted, as well as the restriction on the distribution of spinach from Nasushiobara City and Shioya town in Tochigi prefecture. On 22 April, the restrictions on the distribution of spinach, shungiku, qing-geng-cai, sanchu, celery and parsley produced in Chiba prefecture were also lifted.

On 22 April the chief cabinet secretary Mr. Edano announced that "a decision has been made to prohibit the cultivation of rice for the duration of the 2011 harvest within the evacuation zones, planned evacuation zones and emergency evacuation preparation zones", in Fukushima prefecture (http://www.kantei.go.jp/foreign/incident/110422_0944.html). This measure concerns rice grown for human consumption on the land most affected by the deposition of radionuclides.

On 25 April in Fukushima prefecture restrictions on the distribution of shiitake mushrooms produced in Iwaki City were lifted. Restrictions were placed on the distribution of shiitake mushrooms from Motomiya City.

3. Marine monitoring

Marine monitoring programmes

Further to previous briefings, new monitoring points have been announced by TEPCO, with sampling starting 25 April. FIG. 1 shows existing and new TEPCO sampling points, as well as existing and new MEXT sampling points.

The Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) added further sampling points in its off-shore monitoring programme on 25 April (see FIG. 1). In addition, sampling has started (on 25 April) in five off-shore points off Ibaraki Prefecture.



FIG. 1. TEPCO and MEXT sea water sampling locations.

Monitoring at off-shore sampling points consists of:

1. Measurement of ambient dose rate in air above the sea;
2. Analysis of ambient dust above the sea;
3. Analysis of surface samples of sea water;
4. Analysis of samples of sea water collected at 10 m above the sea bottom.

UPDATE, 11 am, Wednesday, April 27, 2011. Bloomberg News reports today that 2 robots entered the Unit 1 reactor building and took radiation readings inside of 1120 MilliSieverts/hour (about 112 rems/hour)—among the highest readings measured since the onset of the accident. A worker would receive a maximum annual dose (by Japanese standards) in less than 15 minutes; in the U.S. a worker could stay less than three minutes before receiving the maximum allowable dose (a member of the public could be exposed to that level for only about a second…).

A new video from nuclear engineer Arnie Gunderson of Fairewinds Associates postulates that the Unit 3 explosion was sparked by a criticality in its fuel pool. The video includes excellent footage and a clear explanation. Worth seeing.

The New York Times today reports on a “culture of complicity” between Tepco and the Japanese government that led to unresolved safety issues at Fukushima—and Japan’s other nuclear facilities.

Tepco has released an interesting map of outdoor contamination levels at the Fukushima site, indicating where highly radioactive rubble has been found.



Update, 27-Apr-2011, 1700 UTC

(JAIF) Radiation monitors were given to 55 educational facilities from kindergartens to high schools of Fukushima Prefecture.

(JAIF) Workers are removing radiation-tainted topsoil from school grounds in the northeastern Japanese city of Koriyama.

Tests have begun on No. 1 and No.3, injecting more water into the reactors than in the past. Then, 18 hours later they will send in the Robots to check for leaks.

Japan’s science ministry has for the first time released a map projecting estimated cumulative radiation exposure near the Fukushima Daiichi nuclear power plant. The science ministry says it will update its data twice a month on its website. It also says it plans to release a map of radiation levels in the soil.

Ongoing concerns about a leak at No.4 fuel pool (This has pretty much been proven and documented since early on… why they keep mentioning it as though it’s a new thing is beyond me… I suppose this is simply a slow process of admitting that the issue exists.)

Update, 28-Apr-2011, 1600 UTC

The Japan health ministry plans to scrap the annual radiation dose limit for nuclear power plant workers… to secure enough workers for maintenance and checkups of nuclear power plants other than the Fukushima power station.

The ‘test’ injection of more water helped to cool the No. 1 reactor core faster and there appeared to be no major leakage from the No. 4 unit’s spent fuel storage pool. However…

…From the Wall Street Journal, Tepco said Thursday they would postpone their plan to cool reactors via the injection of massive amounts of water that would flood the containment vessels that house each unit. The plan to fill the containment vessels is a departure from the current system of continuously injecting water on to the fuel rods. They didn’t say when it might resume.

The trial run saw a more-than-anticipated drop in the temperature and the pressure inside the plant’s No. 1 reactor, raising the possibility that air from outside could enter and spark an explosion when oxygen hits the hydrogen inside the reactor. Similar explosions in the first week of the crisis exacerbated damage and radiation at the plant.

UPDATE, 12:30 pm, Friday, April 29, 2011. Toshiso Kosako, a University of Tokyo professor and radiation expert, resigned as a special nuclear advisor to Japan’s Prime Minister Naoto Kan today, in protest over the government’s handling of the Fukushima crisis. Kosako was appointed as an advisor on March 16. He told a news conference—apparently holding back tears-- that ''The prime minister's office and administrative organizations have made impromptu policy decisions, like playing a whack-a-mole game, ignoring proper procedures.'' Kosako specifically pointed to the government’s decision to increase allowable exposures to workers from 100 to 250 MilliSieverts/year (from 10 to 25 rems/year; U.S. allowable level for workers is 5 rems/year) and to the decision to allow schoolchildren in Fukushima Prefecture to be exposed to 20 MilliSieverts/year (2 rems/year; 20 times higher than international standards).

Today is the deadline to sign the petition to Japan’s government to object to the 20 MilliSieverts/year level for Japan’s children. Please sign this petition here: http://fukushima.greenaction-japan.com/

The International Atomic Energy Agency reports that temperatures in all three reactors (Units 1-3) with fuel in their cores remains above 100 degrees Centigrade, or above the boiling point. Thus, water continues to be boiled off and released as radioactive steam, and must be replenished. However, Tepco has called off efforts to inject massive amounts of water into the reactors to turn them into the “water coffins” described below. Tepco had begun doing that in Unit 1 but has stopped over concerns that increasing water pressure could produce leaks in the pressure vessel that could lead to outside air coming in that might result in a new hydrogen explosion.



Update, 29-Apr-2011, 1700 UTC

Arnie Gunderson’s latest video hypothesizes about the explosion that occurred in Building No. 3, likely a ‘prompt criticality nuclear reaction’ from the 50′x50′x50′ fuel pool (located above the reactor itself) which was likely empty of cooling water leading to a detonation which shot pieces of fuel rods up to 2 miles away from the building.

Gundersen Postulates Unit 3 Explosion May Have Been Prompt Criticality in Fuel Pool from Fairewinds Associates on Vimeo.

IAEA Briefing on Fukushima Nuclear Accident (3 May 2011, 19:50 UTC)

Presentation:
→ Summary of Reactor Status

On Tuesday, 3 May 2011, the IAEA provided the following information on the current status of nuclear safety in Japan:

1. Current Situation

Overall, the situation at the Fukushima Daiichi nuclear power plant remains very serious.

Changes to Fukushima Daiichi Nuclear Power Plant Status

The IAEA receives information from various official sources in Japan through the Japanese national competent authority, the Nuclear and Industrial Safety Agency (NISA). The Update Brief is based on information received by the IAEA Incident and Emergency Centre by 17:00 UTC on 2 May 2011.

Management of On-site Contaminated Water

According to the 25 April evaluation by NISA of the report submitted by the Tokyo Electric Power Company (TEPCO), there is a little less than 70 000 tonnes of stagnant water with high-level radioactivity in the basement of the turbine buildings of Units 1, 2 and 3.

The stagnant water (around 120 m3) in the basement of the turbine building of Unit 6 was transferred to a temporary tank on 1 May. The transfer of stagnant water from the basement of the turbine building of Unit 6 was resumed on 2 May.

Work to block the Unit 2 trench pit was started on 1 May.

Plant Status

On 27 April TEPCO provided an update of the estimated percentage of core damage for Units 1, 2 and 3 following an assessment (the values assessed previously which TEPCO had provided on 15 March are given in parentheses): Unit 1: 55% core damage (70%); Unit 2: 35% core damage (30%); Unit 3: 30% core damage (25%). This reflects a revised assessment rather than any recent changes in conditions in the reactor cores.

White "smoke" continues to be emitted from Unit 2 and Unit 3. There was no more white "smoke" seen emanating from Unit 4 as of 21:30 UTC on 25 April or from Unit 1 as of 21:30 UTC on 30 April.

In Unit 1 fresh water is being continuously injected into the reactor pressure vessel through the feedwater line at an indicated flow rate of 6 m3/h using a temporary electric pump with off-site power.

In Unit 2 and Unit 3 fresh water is being continuously injected into the reactor pressure vessel through the fire extinguisher line at an indicated rate of 7 m3/h using temporary electric pumps with off-site power.

On 29 April TEPCO checked the status inside the reactor building of Unit 1 using a remotely controlled robot and confirmed that there was no significant leakage of water from the primary containment vessel. Nitrogen gas is still being injected into the containment vessel in Unit 1 to reduce the possibility of hydrogen combustion inside the containment vessel. The indicated pressure in the reactor pressure vessel is still increasing.

In Unit 1, the indicated temperature at the feedwater nozzle of the reactor pressure vessel is 142 °C and at the bottom of reactor pressure vessel is 106 °C.

In Unit 2 the indicated temperature at the feedwater nozzle of the reactor pressure vessel is 118 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure. On 28 April an amount of 43 tonnes of fresh water was injected into the spent fuel pool using the spent fuel pool clean-up system.

In Unit 3 the indicated temperature at the feed water nozzle of the reactor pressure vessel is 99 °C and at the bottom of the reactor pressure vessel is 124 °C. The reactor pressure vessel and the dry well remain at atmospheric pressure.

On 2 May an amount of 55 tonnes of fresh water was injected into the Unit 2 spent fuel pool using the fuel pool clean-up system.

There has been no change in the status in Unit 5 or in the common spent fuel storage facility.

Spraying of anti-scattering agent at the site is continuing. An area of about 1 000 m2 on the south side of the turbine building of Unit 4, and an area of about 4 400 m2 of the surface on the slope around the former main office building, near the on-site gymnasium and on the west side of the shallow draft quay, were sprayed on 1 May.

2. Radiation Monitoring

The daily monitoring of deposition of caesium and iodine radionuclides for the 47 prefectures continues. Deposition of Cs-137 and Cs-134 was detected in six prefectures on 2 May. The values reported ranged from 2.6 Bq/m2 to 19 Bq/m2. Compared with recent data, deposition of these radionuclides has been detected in fewer prefectures and in lower amounts than for previous days.

Gamma dose rates are measured daily in all 47 prefectures. A general decreasing trend has been observed in all locations since around 20 March. Gamma dose rates reported on 2 May remain at 1.7 µSv/h for Fukushima prefecture and 0.11 µSv/h for Ibaraki prefecture. The other 45 prefectures had gamma dose rates of below 0.1 µSv/h, falling within the range of local natural background radiation levels.

Gamma dose rates reported specifically for the eastern part of Fukushima prefecture, for distances of more than 30 km from the Fukushima Daiichi plant, ranged from 0.1 µSv/h to 19.7 µSv/h, as reported on 2 May.

Since 1 April there has been one remaining restriction on the consumption of drinking water relating to I-131 (with a limit of 100 Bq/L), which is applicable only for one village in the Fukushima prefecture and only for infants. According to the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT), I-131 was detected in one prefecture on 29 April, with a reported value of 0.22 Bq/L; in two prefectures on 30 April, with reported levels of 0.04 Bq/L and 0.10 Bq/L respectively; and in one prefecture on 1 May, with a reported level of 0.38 Bq/L. Cs-137 was reported on 30 April in only one prefecture, with a measured level of 0.05 Bq/L. All these levels are below the limits set by the Japanese authorities for the restriction of water consumption due to the presence of radionuclides. The other samples did not show levels of radionuclides above the detection limit for I-131, Cs-134 and Cs-137.

Food Restrictions

On 1 May restrictions were lifted on the distribution of raw unprocessed milk in Fukushima prefecture from the city of Minamisouma (limited to Kashima-ku and excluding Karasuzaki, Ouchi, Kawago and Shionosaki areas) and Kawamata town (excluding Yamakiya area).

3. Marine Monitoring

The marine monitoring programme is carried out both near the discharge areas of the Fukushima Daiichi plant by TEPCO and at off-shore stations by MEXT. (The locations of the sampling positions have been provided in previous briefings.) Increased radioactivity in the marine environment occurred by aerial deposition and by discharges and outflow of contaminated water with a high radioactivity level.

Marine Discharges

In a news release issued on 25 April, NISA communicated its evaluation of a report submitted by TEPCO on 21 April in relation to contaminated water with a high radioactivity level that flowed out from Unit 2 of the Fukushima Daiichi plant. The outflow rate is estimated to have been approximately 4.3 m3/h. The concentrations of the relevant radionuclides, estimated from measurements, were 5400 MBq/L of I-131, 1800 MBq/L of Cs-134 and 1800 MBq/L of Cs-137.

Seawater Monitoring

The activity concentrations of I-131, Cs-134 and Cs-137 in sea water at the screen of Unit 2 were measured every day from 2 April to 30 April. The concentrations fell by several orders of magnitude from initial values of more than 100 MBq/L at the beginning of April to less than 10 kBq/L for Cs-134 and Cs-137 on 30 April, with a continuing decreasing trend. However, levels of I-131 remained at around 100 kBq/L from 26 April to 30 April at this sampling position. The sandbags containing Zeolite® absorbers that were placed at several locations between Unit 2 and Unit 4 to reduce the concentrations of Cs-134 and Cs-137 seem to be effective.

The concentrations of the relevant radionuclides at the other TEPCO sampling positions show a general decreasing trend up to 30 April.

Monitoring performed by MEXT at off-shore sampling positions consists of:

* Measurement of ambient dose rate in air above the sea;
* Analysis of ambient dust above the sea;
* Analysis of surface samples of seawater; and
* Analysis of samples of seawater collected at 10 m above the sea bottom.

The analysis for almost all sampling positions has shown a general decreasing trend in concentrations of the relevant radionuclides over time. Samples were taken at stations 1 - 10 every four days after 2 April. Activity concentrations at MEXT sampling points 30 km off-shore are significantly lower than those at TEPCO sampling points 15 km off-shore. None of the activity concentrations of I-131 and Cs-137 in surface samples taken from points 1, 3, 5, 7, 9 and S-3 on 27 April and from points 2, 6 and S-4 on 25 April were above the detection limits. Samples taken from points 4, 8 and 10 showed concentrations of Cs-137 between of 10.5 Bq/L and 40 Bq/L. Only the sample from point 10 had an I-131 activity concentration, at 21.5 Bq/L, that was above the detection limit.

Samples were taken at the recently added off-shore stations at the Ibaraki prefecture on 25 April. There were no activity concentrations of I-131 and Cs-137 in the surface layer of sea water that were above the detection limits.

Radiation Monitoring in Ports

On 22 April the Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) issued guidelines for radiation measurements in ports in Japan in order to provide foreign port authorities with accurate data. The guidelines cover gamma dose rate measurements for export shipping containers and shipping as well as radiation monitoring of the atmosphere and of sea water in ports.

Measurements relating to export shipping containers for export and to shipping can be conducted by the port authorities, by ship operators or by other parties. The guidelines specify the measuring locations and methodology, as well as criteria for decontamination and for reporting. If measurements have been conducted in accordance with the guidelines, attestations of the measured dose rates will be issued jointly by MLIT and the port authorities.

With regard to export shipping containers, the guidelines state that decontamination is necessary if the measured dose rate exceeds three times the dose rate due to natural background radiation. Decontamination is to be carried out in an area to be specified by the port authorities. In accordance with the International Maritime Dangerous Goods Code of the International Maritime Organization, a reporting level of 5 µSv/h is set. If the dose rate exceeds this reporting level, all relevant organizations are to be informed.

With regard to shipping, the guidelines recommend that decontamination should be carried out if the measured dose rate exceeds three times the dose rate due to natural background radiation, and decontamination must be carried out if the dose rate exceeds 5 µSv/h.

Radiation measurements in the atmosphere and in sea water in ports will be carried out by the port authorities or by MLIT.

Meltdown Confirmed at Fukushima Daiichi


Tokyo Electric Power Company (TEPCO) has announced that fuel rods in the #1 reactor at Fukushima Daiichi power plant have melted. At a press conference, they said that the reactor was in a state of “meltdown”:

The utility company said on Thursday that most of the fuel rods are likely to have melted and fallen to the bottom of the reactor. Earlier in the day, it found that the coolant water in the reactor is at a level which would completely expose nuclear fuel rods if they were in their normal position.

The company believes the melted fuel has cooled down, judging from the reactor’s surface temperature.

But it suspects the meltdown created a hole or holes in the bottom of the reactor causing water to leak into the containment vessel.

It also suspects the water is leaking into the reactor building.

High radiation levels had preventing people from entering the #1 reactor building since March 12, so there had been no way of knowing the exact state of the reactor. About a week ago, it was decided that a drop in radiation levels finally allowed workers to begin very limited work within the building. The renewed access to the reactor #1 building has allowed workers to better observe the conditions within the reactor, so we now have confirmation that fuel has indeed melted (in other words, a “meltdown”). Nobody can be 100% sure when the melting occurred, although it probably wouldn’t be unreasonable to assume that it happened back in March, when workers were unable to pump large amounts of water into the reactors.

Since March, scientists and experts had been predicting that there the situation could have resulted in partial or total melting of fuel. According to one scientist intereviewed by the Japan Times, this latest announcement is not surprising:

“It’s neither a surprise nor bad news,” Kunihiko Takeda of Chubu University told The Japan Times. “This means Tepco has been pumping lots of water in the reactor without knowing what exactly is happening in it, which is the best thing Tepco could do.” He added that reactors No. 2 and 3 may also be in the same situation.

The new finding doesn’t increase the likelihood of a hydrogen explosion because the temperature in the pressure vessel is still low, experts said.

The news will likely make TEPCO’s cooling plans take longer than expected, but it does not indicate the existence of any gigantic new radiation leak into the environment. However, radioactive water is probably leaking into the reactor building itself:

It is highly likely that water is leaking from both the pressure vessel and containment chamber and flowing into underground parts of the reactor building and the adjacent turbine building, TEPCO officials said.

If the basement of the building is flooded with water, it will make it harder to clean up the building. However, it doesn’t mean that the water from reactor #1 is going into the ocean. So far, the only known ocean leakage has occurred at reactor #2 and reactor #3.

The situation in Fukushima remains serious, but the announcement of a confirmed meltdown does not indicate a significant new danger to the safety or health of people in the region.