Japan PM to visit nuclear disaster zone

(Reuters) - Japan's prime minister was headed on Saturday to the disaster zone where workers are braving radiation from a crippled nuclear plant to battle the world's worst atomic crisis since Chernobyl.

Naoto Kan was due to visit a sports camp turned into a base for military, firefighters and engineers working inside an evacuation zone to cool the six-reactor Fukushima Daiichi complex and contain contamination before Japan seeks a permanent solution.

The base camp itself is located inside the 20-km (12-mile) radius evacuation area.

Kan has warned of a "long-term battle" at Fukushima, where the nuclear crisis entering its fourth week has compounded national anguish after an earthquake and tsunami that left 28,000 people dead or missing.

"We are focusing on stabilizing the conditions there using every bit of expertise available," he said before leaving. "I am convinced we will be able to achieve it. I do not know for now how long this will take."

The 64-year-old Kan's popularity was already low before the disaster. Critics have accused him both of poor leadership during the crisis and of hampering emergency efforts by flying over Fukushima Daiichi the day after the quake.

As well as seeing the operation first hand on Saturday, Kan aimed to give a morale boost to workers operating in appalling conditions as they enter dark and mangled corners of the complex to try to restart pumps needed to stop fuel rods overheating.

He was also to visit the beach town of Rikuzentakata, flattened into a wasteland of mud and debris by the wave that crashed into the northeast Pacific coast on March 11.

Kan is leading Japan during its toughest moment since World War Two. As well as the nuclear crisis, the Asian nation has more than 166,200 people in temporary shelters and a damage bill that may top $300 billion -- the world's biggest from a natural disaster.

Japan's prime minister is not the only one under pressure.

Plant operator Tokyo Electric Power Co (TEPCO), Asia's largest power company, has seen its shares lose 80 percent -- $32 billion in market value -- since the disaster.

With its president, Masataka Shimizu, in hospital, an enormous compensation bill looming and mounting criticism of both its handling of the crisis and prior safety preparations, TEPCO may need state help, according to media reports.

Prime Minister Kan said he wanted TEPCO to continue to "work hard as a private company," but some sort of injection of public funds looks inevitable.

Standard & Poor's on Friday cut its long-term rating on TEPCO by three notches to "BBB+," in its second downgrade on the electric utility in as many weeks.

"We expect TEPCO's operating performance to remain weak, and we believe it will take a prolonged period of time for it to recover," the credit ratings agency said in a statement.