Troubles Mount at Quake-Stricken Japanese Nuclear Reactor

An explosion blew the roof and outer walls off of the number 3 unit Monday at the Fukushima nuclear power plant in earthquake-stricken northern Japan.

A similar explosion struck the number 1 unit on Saturday at the plant, where cooling systems were knocked out by Friday's devastating earthquake and tsunami.

Officials said the inner containment vessel remained intact after Monday's explosion and they did not believe there had been a major release of radiation.

However engineers were still struggling to gain control of a new threat at the number 2 unit, where officials reported a total failure of the cooling system. The operators of the plant, Tokyo Electric Power Company, said the coolant had evaporated exposing the fuel rods, raising the risk of them melting down.

If the heat from a meltdown ruptures the containment vessel, that could permit a major release of radiation with serious health consequences. Engineers were desperately pumping sea water into all three units at Fukushima in an effort to cool them down.

Engineers have also vented steam from the plants to release a build-up of pressure. Hydrogen in the steam is believed to have mixed with oxygen, causing the two explosions.

Evacuations

Almost 200,000 people have already been evacuated from areas around Fukushima and other troubled nuclear power stations. About 600 people still in homes near the Fukushima plant were advised to remain indoors.

The commander of the aircraft carrier USS Ronald Reagan, which has been assisting in relief efforts from about 160 kilometers offshore, said the American fleet had moved away from the Fukushima plant after low levels of radiation were detected on 17 crewmen. He said the radiation was easily washed off.

The nuclear crisis has diverted attention away from a massive rescue and relief effort. The total death toll from the quake and tsunami is expected to reach more than 10,000.

The search for survivors

About 100,000 Japanese troops, backed by relief teams from more than a dozen countries, are searching for survivors in the debris of Friday's earthquake and tsunami, which reduced whole towns and villages to rubble. Power shortages and massive damage to infrastructure are complicating efforts to reach the hardest-hit areas.

More than 1,000 bodies were found Monday along the shores of one northeastern province, and the Kyodo news agency said another 1,000 bodies were found at a second location in hard-hit Miyagi province.

Also Monday, officials sounded tsunami warnings and ordered residents to head for higher ground along the devastated northeastern coast near the city of Sendai following a major aftershock. The alert turned out to be a false alarm but further jangled the nerves of a frightened population.

Markets tumble

In Tokyo, residents returned to shops and offices at the start of a new work week, coping with rolling blackouts and reduced transit service as authorities deal with limited power-generating capacity. Fears that industrial production will be disrupted helped push the main stock index to its lowest levels since November.

There is no electricity at all in vast stretches of the northeast region, where tens of thousands of homeless residents spent a third night in near-freezing temperatures without heat or running water. Relief crews are rushing to provide food and water, but are hard-pressed to reach many of those in greatest need.

Two U.S. search-and-rescue teams with 144 staff and 12 dogs were among the teams that began clawing through the ruins at first light Monday in search of survivors. A 15-member Chinese team was also at work and Japan's Kyodo news agency said the Defense Ministry will activate reserves to assist in relief operations, the first time it has ever done so.

Friday's earthquake had a magnitude of 8.9, making it the most powerful ever recorded in Japan and the fifth strongest since 1900.

Infection is main risk for most with radiation sickness

While officials in Japan and elsewhere are offering assurances that the health risks posed to the general public by three nuclear reactors are low, many are still worried.

Some are surely remembering images of the 1986 Chernobyl disaster. That disaster is thought to have caused more than 30 deaths from acute radiation sickness alone, as well as thousands of cancer deaths, and birth defects.

So far, the two events seem quite different.

At Chernobyl, explosions blew the reactor apart, which vapourized its radioactive fuel, sending a toxic cloud across the Ukraine and parts of Europe. In Japan, explosions have been contained within the reactors, and only small amounts of radioactive particles are said to have been released.

The radiation release from Chernobyl was about a million times the amount released from the partial core meltdown at Three Mile Island, which itself is considered a worse disaster than the troubles underway at Japan's Fukushima facility.

Acute radiation sickness

Nevertheless, at least three Fukushima workers have already come down with acute radiation sickness. Since it's unclear how much radioactive material they were exposed to, what kind of radiation, and for how long, their prognosis is uncertain.

Officials haven't revealed what symptoms the workers are experiencing, but they likely include nausea, fatigue, vomiting, and diarrhea. More severe radiation exposures result in fever, bloody vomit and stools, and later, hair loss, infections, and poor wound healing.

What makes ionizing radiation from radioactive material so dangerous is that it interferes with the cells' ability to divide and reproduce. The effects are usually seen first in the cells that divide rapidly. These include blood cells in bone marrow and intestinal cells, as well as reproductive and hair cells.

For most with radiation sickness, the biggest risk is infection.

Though severe radiation exposure is fatal within weeks about 50 per cent of the time, many can survive milder forms of radiation sickness.

If the Fukushima workers develop more serious symptoms in the next few weeks, they would likely be offered medications that increase white blood-cell production, which can help reduce the risk of infections.

But the risk of cancer will remain for the workers for many years down the road.

Cancer risk

For the rest of the Japanese public, there is still a risk of long-term effects of radiation exposure, particularly is officials are downplaying the severity of the situation, as some suspect they might be.

The Japanese government has ordered anyone living within 20 kilometres of the Fukushima nuclear power plant to evacuate the area as a precaution. They are also handing out iodine pills in hopes of preventing thyroid cancer.

The reason for the pills is that the thyroid gland tends to absorb iodine from wherever it can. By flooding the thyroid with ordinary iodine, it will inhibit its absorption of radioactive iodine from the atmosphere.

But Dr. David J. Brenner, director of the Center for Radiological Research at Columbia University, is not convinced that's an effective strategy. He tells The New York Times that the risk from inhaling radioactive iodine is low; almost 98 per cent of people's exposure comes from ingesting contaminated milk and other dairy products.

In fact, he believes that the epidemic of thyroid cancer around Chernobyl could have been prevented if the government had immediately stopped people from drinking milk.

Leukemia is also a risk, as many of those who survived Chernobyl eventually came down with the blood-based cancer.

Cancer is the biggest long-term risk. Usually when the body's cells reach their "sell-by date" they commit suicide. Cancer results when cells lose this ability,

The body has various processes for ensuring that cells do not become cancerous, and for replacing damaged tissue.

The damage caused by exposure to radiation can disrupt the body's ability to regenerate new cells, allowing old cells to "go rogue" and continue to divide and multiply in an uncontrolled fashion, allowing tumours to grow.

Radiation can also result in mutations to the body's genetic material, which may also be potentially passed down to offspring, leading to deformities in future generations.

These can include smaller head or brain size, severe learning difficulties, and stunted growth.