TEPCO starts removing fuel from Fukushima No. 4 pool

TOKYO (Kyodo) -- The operator of the Fukushima Daiichi nuclear power plant started a yearlong mission Monday to remove fuel from a pool at a damaged reactor building, in a move to address one of the major hazards remaining at the accident-stricken plant.

While the process of removing fuel assemblies from the spent fuel pool of the No. 4 reactor unit is a milestone toward the decommissioning of Tokyo Electric Power Co.'s Fukushima plant, the work will require careful attention so as not to result in another radiation-leaking incident.

The Nos. 1 to 4 units lost their cooling systems during the 2011 nuclear crisis, as huge quake-triggered tsunami waves knocked out most of the emergency diesel power generators at the site.

The No. 4 unit suffered damage to the building due to a hydrogen explosion, but avoided a reactor meltdown, unlike the Nos. 1 to 3 reactors, as all of its fuel was stored in the spent fuel pool due to the reactor undergoing periodic maintenance work at that time.

However, the condition of the spent fuel pool on the highest floor of the crumbling building was a major source of concern in the early days of the crisis, as the water level was suspected to have dropped low enough to expose the fuel. TEPCO later said the fuel of the No. 4 unit was unlikely to have sustained major damage.

To ensure radioactive substances will not spread outside during the fuel removal work, TEPCO has created a huge cover, supported by steel frames, to blanket the reactor building.  (CONTINUED) (LINK)

Japan's Fukushima nuclear plant begins fuel rod removal

The delicate operation is seen as a necessary step in stabilising the site.

It will take about two days to remove the first 22 fuel rod assemblies, plant operator Tepco says.

Overall, more than 1,500 assemblies must be be removed in what correspondents describe as a risky and dangerous operation set to take a year.

Experts say hydrogen explosions after the earthquake and tsunami in March 2011 have made the current storage facility vulnerable to further tremors.

The fuel rod assemblies are four-metre long tubes containing pellets of uranium fuel, and the fear is that some may have been damaged during the disaster.

Removing fuel rods

• The fuel rods - 4m-long tubes containing pellets of uranium fuel - are in a precarious state in the Unit Four storage pool
• The rod assemblies will be lifted out in batches of 22 in casks filled with water, using a crane - each batch will take 7-10 days
• Two critical issues are whether the rods were damaged during the disaster and so are likely to leak, and whether the casks remain watertight so the rods have no contact with air
• The fuel rods will be deposited into a new "common" pool with a cooling system

• (continued)  (LINK)

Operator at Japan's Fukushima starts hazardous year-long fuel removal

TOKYO (Reuters) - The operator of Japan's wrecked Fukushima nuclear plant took the first step on Monday in the long and hazardous process of decommissioning the facility, extracting four fuel rods from their container for later removal.

Tokyo Electric Power Co, known as Tepco, said it transferred the rods to a steel cask within the same cooling pool in a badly damaged reactor building, beginning the delicate and unprecedented task of removing 400 tonnes of highly irradiated spent fuel from that reactor.

"We will continue with the work from tomorrow and proceed, paying close attention to safety," Tepco said in a statement.

While battling leaks of radiation-contaminated water around the plant, which was knocked out by Japan's mammoth March 2011 earthquake and tsunami, Tepco has embarked on decommissioning four reactors at the Fukushima Daiichi plant. That task is likely to take decades and cost tens of billions of dollars.

The company must carefully pluck more than 1,500 brittle and potentially damaged assemblies from the unstable reactor No. 4. Tepco estimates that removing all the rods from the reactor will take a year, although some experts say that is an ambitious target.

The cask holds 22 rods. Transferring this first batch will take about two days and it will take about a week to get the cask to the common storage pool in another building, a Tepco spokesman said.

Moving them is urgent because they are being stored 18 metres (59 feet) above ground level in a building that has buckled and tilted and could collapse if another quake strikes. (continued)  (LINK)