By Mari Saito
TOKYO (Reuters) - U.N. nuclear experts arrived in Japan on Monday to assess the decommissioning of the wrecked Fukushima nuclear plant and the operator's progress in removing fuel rods from a destroyed reactor building and minimizing leaks of contaminated water.
The International Atomic Energy Agency (IAEA), the U.N.'s watchdog for nuclear power, is conducting its second review of plans for decommissioning that may take four decades after the world's worst nuclear accident since Chernobyl in 1986.
The Fukushima Daiichi nuclear plant, 220 km (130 miles) north of Tokyo, was wrecked by a huge earthquake and tsunami in March 2011. More than 150,000 residents were evacuated after the natural disasters triggered three nuclear meltdowns.
During their last review in April, the IAEA was critical of the cleanup effort by the plant's operator, Tokyo Electric Power Co, saying its plan had an unrealistic time frame and calling for a comprehensive approach to handling contaminated water.
The government, academics and other experts have since roundly criticized the utility, known as Tepco, over a long series of leaks of contaminated water. The company acknowledged in July that radiated water had been reaching the Pacific Ocean, probably since the disaster.
"There continues to be significant public disquiet over the disclosure of various issues around the Fukushima plant, including the water contamination issue into the Pacific Ocean despite the government's increased involvement in the clean-up activities," Tom O'Sullivan, founder of independent energy consultancy Mathyos Japan.
A team of 19 experts from the IAEA and other bodies will tour the plant on Wednesday and evaluate Tepco's fuel extraction process at the No. 4 reactor and its handling of contaminated water. It concludes its review on Dec 4.
"They must look into Tepco's overall management of the site," Masashi Goto, a retired Toshiba' nuclear engineer and critic of Tepco. "They shouldn't just look at each little issue. They should look at the organizational challenges at Tepco that have created the recent string of incidents."
IMPROVED WATER MANAGEMENT
After the government said in September it would step in to oversee the process, water management has improved. That has allowed Tepco to turn to the real decommissioning work and start removing the spent fuel rods - a process described by one expert as similar to removing cigarettes from a crushed pack.
Tepco last week completed the removal of the first batch of rods from a cooling pool. Its technicians must pluck more than 1,500 brittle and potentially damaged assemblies from a pool stored 18 meters (59 feet) above ground level in a building now tilted from the quake.
The fuel extraction is an early stage in the decommissioning process and serves as an important test for a skeptical government and public that the utility can handle the cleanup.
The experts will also assess efforts to treat and find storage space for hundreds of tonnes of radioactive water that Tepco dumps over the wrecked reactors every day to keep them cool.
The acknowledgement that 300 tonnes of highly radioactive water had leaked from one of the hastily built tanks on site triggered international alarm over Japan's handling of the cleanup.
The government has pledged additional funds to deal with radioactive water.
Tepco has also promised to double pay for workers after coming under fire for labor conditions inside the wreckage of the plant.
A Reuters investigation last month found that workers' pay was being skimmed, some employees had been hired under false pretences and some contractors had links to organized crime gangs.
(Editing by Aaron Sheldrick and Ron Popeski)