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福島原子力発電所
福島第一原子力発電所 Number 1
福島第二原子力発電所 Number 2
Fukushima Number One nuclear power plant
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. Fukushima, radiation . . .
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Since March 18, 2011, from the Japan Times
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Fukushima prefecture
(the fortunate island, the blessed island 福島) is a large prefecture and a big producer of agricultural products. Only a small part along the coast is affected by the Fukushima reactor problems.
But the vegetables and other products of the whole prefecture are now under scrutiny and face difficulties in selling.
The town of Iwaki is especially "damaged by the wind",
fuuhyoo higai 風評被害) harmful rumors.
Farmers want the authorities to apply special lables to their vegetables, saying they are safe.
Distance from the reactor to major towns in Fukushima prefecture:
(in case of furthere evacuation radius)
* ca. 53 km - Iwaki (ca. 342.000 inhabitants)
* ca. 57 km - Kooriyama (ca. 340.000 inhabitants)
* ca. 75 km - Fukushima (ca. 292.000 inhabitants)
Fukushima Prefecture 福島県 Fukushima-ken
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Fukushima Town 福島市 Fukushima-shi
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Timeline of the Fukushima nuclear accidents
Wednesday, 30 MarchSmoke escaped from the Fukushima II (Dai-ini) nuclear plant. Fukushima II plant is 6 miles from the Fukushima I (Dai-Ichi) facility, and was thought not to be at risk.
All the details are HERE:
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March 15, 2011
source : NHK www3.nhk.or.jp
No.1 reactor chronology
On Friday night, the Tokyo Electric Power Company informed the government that there was a state of emergency at the No. 1 reactor of its Fukushima No. 1 nuclear power plant.
The utility explained that the emergency power generator for cooling the reactor was not functioning, and that it was unable to confirm the status of the reactor's cooling systems.
The level of cooling water continued to decline through Saturday, while the pressure in the nuclear containment vessel increased.
To prevent the container from being damaged, workers began to release air, which included radioactive substances. But the water level continued to fall, exposing the fuel rods up to 1.7 meters above the surface of the water.
Radioactive substances, including cesium and iodine, were detected around the reactor, suggesting the possibility that the fuel rods had melted.
While the air-release and water-pumping work was continuing on Saturday, the housing of the No.1 reactor suddenly exploded. The building's ceiling and walls were blown off, and 4 workers sustained injuries.
Experts think that hydrogen gas created by the damaged fuel rods filled the inside of the building and exploded in a chemical reaction with oxygen.
On Saturday night, after detecting no damage to the containment vessel, workers began pumping seawater into the reactor to cool it down. By Sunday morning, the reactor was filled with seawater.
The Nuclear and Industrial Safety Agency says the reactor would pose no danger if the pumps continued working and filling it with seawater.
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No.2 reactor chronology
Three of the 6 nuclear reactors at the Fukushima Number One nuclear power plant automatically halted operations at 2:46 PM on Friday after the earthquake struck.
But the emergency power generator to cool the reactors failed to work.
Tokyo Electric Power Company notified the government that a state of emergency existed based on laws governing nuclear issues. The government then instructed nearby residents to evacuate.
At the No.2 reactor, the cooling water had partially evaporated, considerably reducing the water level inside the nuclear containment vessel.
Two days after the earthquake, on Sunday, the pressure rose.
To prevent the container from being damaged, work began to release the inside air which includes radioactive substances.
But on Monday, the pressure increased further, and the water level also dropped.
TEPCO began to pump in sea water on Monday afternoon. But the pump ran out of fuel and the water level remained low. The 4 meter tall fuel rods are believed to have been fully exposed for 2 hours and 20 minutes.
Shortly after 9:30 PM, high levels of radiation measuring 3,130 microsieverts per hour were recorded near the plant gates. It is believed that the fuel rods were likely damaged and melted.
At around 6:10 Tuesday morning, an explosion was heard near a facility known as the suppression pool, which adjusts the pressure of the No.2 reactor.
At one point immediately after the explosion, radiation levels near the power plant reached 965.5 microsieverts.
The facility is believed to have sustained damage, and radioactive substances are unlikely to have been sufficiently contained.
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No.3 reactor chronology
Immediately after the earthquake, water was pumped into the No.3 nuclear reactor of the stricken Fukushima plant to prevent overheating.
But 2 days later, on Sunday, the system to provide water stopped operating and an emergency was declared.
The pressure in the reactor's containment vessel rose while the water level dropped, leaving some of the fuel rods exposed and possibly damaging and causing them to melt.
So work began to pump sea water into the reactor, but the operation was suspended due to a lack of water.
Shortly after 11:00 AM on Monday, the hydrogen which had accumulated inside the No.3 reactor exploded, blowing away the ceiling and outer walls.
Eleven TEPCO employees and Self Defense Force members were injured.
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No.4 reactor chronology
The No.4 reactor at the Fukushima No.1 nuclear power plant had been shut down for regular inspection since November last year.
There was no nuclear fuel in the reactor, and its 783 fuel rods had been removed to a pool for spent nuclear waste.
The pool's temperature more than doubled to 84 degrees Celsius as of 4:18 AM on Monday after its cooling system broke down.
An explosion occurred at around 6:00 AM on Tuesday. The roof of the No.4 reactor building was found to have been damaged.
At around 9:00 AM, a fire was confirmed in the reactor building. The plant's operator promptly issued an emergency alert.
The fire was later put out, but a radiation level of 100 millisieverts per hour was detected around the reactor building at 10:22 AM on Tuesday.
The blast may have been a hydrogen explosion triggered by vaporization of the pool water, which resulted in fuel rods being exposed.
The plant's operator is rushing to cool the reactor by injecting water, as it did for the No.1 and No.3 reactors.
Fire at No.4 reactor put down
Tokyo Electric Power Company says the fire has been extinguished at the No.4 reactor at the quake-hit nuclear power plant in Fukushima prefecture.
Company officials said that the fire had started at 9:38 AM local time on Tuesday near the northwestern part of the 4th floor of the building that houses the reactor at the Fukushima No.1 nuclear power plant.
The officials said before the fire, an explosion was heard and that an area near the roof of that building was found to have been damaged.
TEPCO is confirming reports that the temperature of the pool which contains spent nuclear fuel had risen from its usual 40 degrees Celsius to 84 degrees.
A company official says a hydrogen explosion is thought to have occurred at the No.4 reactor, but details including its relation to the fire are unknown.
Chief Cabinet Secretary Yukio Edano told reporters shortly after 11:00 AM on Tuesday that a fire had broken out at the No.4 reactor.
He said the reactor has not been operating after the earthquake, but hydrogen is being produced because spent fuel creates its own heat.
He said so it can be inferred that a hydrogen explosion similar to those that took place at the No. 1 and 3 reactors occurred.
Tuesday, March 15, 2011 13:48 +0900 (JST)
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Wednesday, March 16, 2011 17:19
Here's what has happened so far on Wednesday at the Fukushima Daiichi Nuclear Power Station.
At around 5:45 AM, a Tokyo Electric Power Company, or TEPCO, employee noticed flames coming out of the Number Four reactor building. The power company says the flames were not visible half an hour later.
The fire occurred at almost the same place where a blaze erupted Tuesday morning. TEPCO had said that fire died out by itself.
Wednesday's fire occurred where two 8-square-meter holes could be seen on the building's outer wall on Tuesday.
The cause of the fire has not been determined. The fire may be linked to the temperature rise in the pool for spent fuels.
Shortly before 10:00 AM, an NHK helicopter caught footage of what appeared to be white smoke rising from the nuclear power station. The footage showed the smoke rising intermittently. The helicopter was flying more than 30 kilometers away from the site.
TEPCO told reporters that the smoke appeared to be steam coming out of the Number Three reactor building. The steam could indicate that water in the pool is vaporizing. If that is the case it would mean that the cooling system for the pool, which contains 514 spent fuel rods, is not working.
At the Number Two reactor, where the suppression pool was found to be damaged on Tuesday, the likelihood of a radiation leak grew stronger on Wednesday.
The suppression pool is designed to work as a reactor's pressure control system.
The Nuclear and Industrial Safety Agency said the radiation level near the power station's main entrance spiked to 10 millisieverts per hour at around10:40 AM.
The safety agency cited reports from TEPCO that damage to the suppression pool at the Number Two reactor may responsible for the rise in the radiation level.
The company evacuated its workers to safety as soon as it detected a surge in the radiation level near the plant's main entrance.
The evacuation order was lifted less than an hour later, as the radiation level dropped.
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As of morning, March 16, we get closer to the meltdown
White ?smoke?steam is coming out of reactor Nr. 5 now.
READ MORE
. My Daily Report
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quote
The Fukushima I Nuclear Power Plant
(福島第一原子力発電所, Fukushima Dai-Ichi Genshiryoku Hatsudensho, Fukushima I NPP), often referred to as Fukushima Dai-ichi (Dai-ichi simply means first or number 1), is a nuclear power plant located in the town of Okuma in the Futaba District of Fukushima Prefecture, Japan, first commissioned in 1971.
The Fukushima II Nuclear Power Plant, 11.5 kilometres (7.1 mi) to the south, is also run by TEPCO.
The Fukushima II Nuclear Power Plant
(福島第二原子力発電所, Fukushima Dai-Ni Genshiryoku Hatsudensho, Fukushima II NPP, 2F)
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The International System of Units (SI)
specifies a set of seven base units from which all other units of measurement are formed.
System for Prediction of Environmental Emergency Dose Information (SPEEDI):
Rate of space dose (nGy/h)
source : www.bousai.ne.jp values in Japan
The unit gray (Gy) measures absorbed radiation which is absorbed into any material.
absorbed dose (of ionizing radiation)
The unit sievert (Sv) specifically measures absorbed radiation which is absorbed by a person.
1 rem = 0.01 Sv = 10 mSv
equivalent dose (of ionizing radiation)
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The becquerel (symbol Bq) is the SI-derived unit of radioactivity. One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second.
radioactivity (decays per unit time)
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half-life, half time (Halbwertzeit)
Half-life is the period of time it takes for a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms (radioactive decay), but may apply to any quantity which follows a set-rate decay.
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When measuring radioactivity of a sample with a detector:
"counts per second" (cps) or
"counts per minute" (cpm)
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. . . . . July 12, 2011
quote
REALITY CHECK:
It's 1 step forward, 2 steps back at Fukushima plant
Four months after the Great East Japan Earthquake, Tokyo Electric Power Co. still has a long and winding road to go before bringing the crisis at the Fukushima No. 1 nuclear power plant under control.
The company has been unable to inject nitrogen into the containment vessel of the No. 3 reactor to prevent another hydrogen explosion.
High levels of radiation have barred workers from entering the reactor building, which was badly damaged by a hydrogen explosion on March 14.
In early July, TEPCO tried to remove radioactive materials from the floor with a robot cleaner, but radiation levels did not fall as expected.
The company laid steel sheets to prevent workers' exposure to radiation.
TEPCO has been injecting nitrogen into the No. 1 reactor building since early April and into the No. 2 reactor building since late June to prevent a hydrogen explosion.
The No. 1 reactor building was damaged by a hydrogen explosion on March 12. Part of the No. 2 reactor building was also damaged by an explosion at the suppression pool on March 15.
At the No. 4 reactor, the water temperature at the storage pool for spent nuclear fuel remained high at about 85 degrees.
MORE
source : www.asahi.com
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. . . . . July 20, 2011
Wednesday, July 20, 2011 10:26 - NHK world news
Expert:
Risks remain at Fukushima Daiichi plant
An expert says that radiation could be released from the Fukushima Daiichi nuclear plant in about 2 and half days if the injection of cooling water into reactors is halted for any reason.
Masanori Naito, 内藤 正典 director in charge of nuclear safety analysis at the Institute of Applied Energy, was speaking to NHK about the revised plan to bring the troubled plant under control. The Japanese government and Tokyo Electric Power Company, the plant's operator, announced the plan on Tuesday.
The government and TEPCO said in a joint assessment that the target of the first stage of the original plan ---- to steadily reduce the level of radiation being released from the plant ---- has been met over the past 3 months.
They said the amount of radioactive substances spewing from the No.1 to No.3 reactors has been cut to one 2-millionth of the peak recorded just after the nuclear accident in March.
The effort to stabilize the nuclear facility now shifts to the second stage, when workers will focus on further cutting the release of radioactive substances over the next 6 months. Emphasis will be on reactor cooling systems that recycle contaminated water. The goal is to achieve cold shutdown by reducing reactor water temperatures to below 100 degrees Celsius.
Naito says nuclear fuel levels at the plant have dropped below one-tenth of what they were immediately after the accident, but warns of remaining risks.
He says the government and TEPCO should explain these risks to nearby residents and whether the existing measures will be sufficient.
コールド シャットダウン 冷温停止 reion teishi
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