PROBLEMS CONTINUE TO mount at Japan’s damaged nuclear complex as the crisis stretches into a third week.

Highly radioactive iodine seeping from Japan’s damaged nuclear complex may be making its way into seawater farther north of the plant than previously thought, officials said on Monday, adding to radiation concerns.

Mounting problems, including badly miscalculated radiation figures and no place to store dangerously contaminated water, have stymied emergency workers struggling to cool down the overheating plant and avert a disaster with global implications.

The coastal Fukushima Daiichi power plant, located 220 kilometres northeast of Tokyo, has been leaking radiation since a magnitude 9.0 quake on 11 March triggered a tsunami that engulfed the complex.

The wave knocked out power to the system that cools the dangerously hot nuclear fuel rods.

On Monday, workers resumed the laborious yet urgent task of pumping out the hundreds of tons of radioactive water inside several buildings at the six-unit plant.

The water must be removed and safely stored before work can continue to power up the plant’s cooling system, nuclear safety officials said.

The contaminated water, discovered last Thursday, has been emitting radiation that measured more than 1,000 millisieverts per hour in a recent reading at Unit 2 — some 100,000 times normal amounts, plant operator Tokyo Electric Power Co. said.

As officials scrambled to determine the source of the radioactive water, chief Cabinet Secretary Yukio Edano repeated Monday that the contaminated water in Unit 2 appeared to be due to a temporary partial meltdown of the reactor core.

He called it “very unfortunate” but said the spike in radiation appeared limited to the unit.

However, new readings show contamination in the ocean has spread about a mile further north of the nuclear site than before.

Radioactive iodine-131 was discovered just offshore from Unit 5 and Unit 6 at a level 1,150 times higher than normal, Hidehiko Nishiyama, a spokesman for the Nuclear and Industrial Safety Agency, told reporters on Monday.

Closer to the plant, radioactivity in seawater tested about 1,250 times higher than normal last week and climbed to 1,850 times normal over the weekend but the contamination posed no immediate threat to human health, according to an official.

Up to 600 people are working inside the plant in shifts.

Nuclear safety officials say workers’ time inside the crippled units is closely monitored to minimize their exposure to radioactivity, but two workers were hospitalised Thursday when they suffered burns after stepping into contaminated water.

They are expected to be released from the hospital today.

Meanwhile, a strong earthquake shook the region and prompted a brief tsunami alert early Monday, adding to the sense of unease across Japan.

The quake off the battered Miyagi prefecture coast in the northeast measured magnitude-6.5, the Japan Meteorological Agency said.

No damage or injuries were reported, and TEPCO said the quake would not affect work to stabilise the plant. Scores of strong earthquakes have rattled Japan over the past two weeks.

Confusion at the plant has intensified fears that the nuclear crisis will last weeks, months or years amid alarms over radiation making its way into produce, raw milk and even tap water as far as Tokyo.

One official acknowledged it could take a long time to clean up the Fukushima complex.

“We cannot say at this time how many months or years it will take,” he said.

- AP