Fukushima Daiichi Nuclear Power Station

TEPCO release images from inside Fukushima Nuclear plant

Tokyo Electric Power Company (TEPCO) released images from inside their stricken Fukushima Daiichi Nuclear power plant, NHK revealed.

“This photo of the first floor of the No.3 reactor building shows a sheet-like object hanging from the ceiling and what appears to be equipment for moving the control rods. TEPCO says it cannot identify whether there are any pools of water on the floor.

The bright area at the innermost part of the building is an entrance for vehicles to bring in large machinery and materials.”

Fukushima Daiichi nuclear power plant suffered heavy damage following a massive 9.0 magnitude Earthquake, and tsunami that struck Northeastern Japan in early March 2011. The International Atomic Agency rated the catastrophe at Fukushima as a Level 7 on its Nuclear Event Scale, the highest level, and describes it as a major accident.

Fukushima nuclear power plant situation explained

I’ll try to explain this without having to go talk about Nuclear plant design. For non-science majors, I wrote “Fukushima nuclear power plant meltdown explained simply” on Blog Watch. This article is going to be a little more technical, but it still won’t be Physics major-level. Pardon its simplistic explanation.

The 2011 Sendai Earthquake was without a doubt the most powerful earthquake to hit Japan, as we have recorded it. People didn’t start keeping record until 1900, so you can imagine that there is vast amount of information that we do not know about. Fukushima started producing electricity in 1971. In February 2011, Japanese nuclear energy regulators gave it another 10 years to operate. Fukushima nuclear power plant was designed to take on an 8.2 earthquake. And the beauty of Japanese Engineering showed through how Fukushima successfully withstood a 9.0 Earthquake, and a 7 meter high tsunami.

Nuclear power plants are designed in such a way that there are cascading backups. And Fukushima had redundancy written all over it. Fukushima suffered what experts call, “Level 4 Nuclear Event Scale. In English, it means an accident has occured but without significant off-site risk. The accident involves a significant damage to the core such as a partial core meltdown, or an overexposure of one or more workers that may lead to death. It also means an off-site release of radiation dose, measured in millisieverts.

There are seven levels of Nuclear Event Scale. The highest is Level 7, which is a Chernobyl-level type of accident where a major level of radioactive material is released causing widespread health and environment problems.

What the Japanese are now doing at Fukushima is preventing a core meltdown. One Unit 1 of the reactor, they have already flooded it with SeaWater mixed with boron. This forces the Core from cooling down.

So what’s the status now? According to Brave New Climate:

“Unit 1: Seawater injection continues and it is thought the reactor core is now sufficiently cool. Safety regulators consider reactor pressure of 353 kPa an indication of a stable condition.

Unit 2: The normal reactor core isolation cooling system is in use. Fuel rods are covered by about 3.8 metres of water.

Unit 3: Operations to relieve pressure in the containment of Fukushima Daiichi 3 have taken place after the failure of a core coolant system. Seawater is being injected to make certain of core cooling. Malfunctions have hampered efforts but there are strong indications of stability.

What of the explosions? Here’s a bit technical explanation of the explosion:

“Gas pressure in steel reactor pressure vessel rises when coolant systems are not active and is vented to reactor building by engineers. {In my view there is not yet plausible evidence that the temperature of the PV water was sufficiently high to spontaneously split water}

j. The hydrogen in the reactor building is ignited in an explosion which blows out the walls but is not likely to have damaged Steel pressure vessel or concrete containment.

{this is true of both scenarios –but the source of the hydrogen is also external to the PV and containment in my explanation, overcoming the problem of why there was not a hydrogen explosion within the containment and outside the PV!}”

The problem really is that there are mixed-signals being given. World Nuclear News reports:
“The Japan Atomic Industry Forum (JAIF) reported back from a press conference given by the Nuclear and Industrial Safety Agency (NISA) at 11.30pm. The trade body said that a malfunctioning guage means that water levels cannot be confirmed. The gauge in question reads that water levels are around two metres below the top of the nuclear fuel assemblies, which would represent a very serious situation with the risk of fuel damage.

“It is unknown whether [the reading] is real or not,” said JAIF. Other readings from the reactor system do not indicate that the reading – and the associated potential damage to fuel – are the true situation. Pressure levels stand at around 250 kPa, compared to reference levels of 400 kPa – and a high of 840 kPa recorded at unit 1 yesterday. Radiation levels have dropped during the seawater injection, said NISA.”

The situation is serious, but manageable.

FAQ on the Japan Nuclear power plant situation.

Japan Fukushima Daiichi Nuclear Power Station meltdown

The Fukushima Daiichi Nuclear power station in quake and tsunami devastated Miyagi prefecture suffered a meltdown of the reactor core, Japan’s Nuclear and Industrial Safety Agency (NISA) announced. In a last ditched effort to avoid a full meltdown, the Japanese government ordered that seawater flood the reactor core to avoid a full meltdown.

The Japanese Nuclear and Industrial safety agency revealed that at least 160 people may have been exposed to radiation. Japanese officials also revealed that while no major health risk is anticipated, they have informed the International Atomic Energy Agency that they are distributing iodine to people living near Daiichi, as well as a second plant. Iodine would help protect thyroid gland from radiation exposure.

Flooding the plant with seawater means it is effectively scrapped. Fukushima Daiichi nuclear power station is almost 40 years old. The exact sequence of failures have not been explained.

NISA is the Japanese agency that reports to the Agency for Natural Resources and Energy, a branch of the Ministry of Economy, Trade and Industry. NISA works with the International Atomic Energy Agency, and provides oversight to Japan’s Nuclear industry. NISA have been criticized for approving nuclear plants near fault lines, and it was also NISA who issued the order to open valves to release pressure from the plant.