New America Media, News Analysis, Yoichi Shimatsu, Posted: Mar 12, 2011

A day after Japan’s devastating Tohoku earthquake and tsunami, core meltdown is underway the Fukushima No.1 nuclear power plant and, at this point, appears to be unstoppable. A mid-afternoon blast on Saturday demolished the structure housing an overheated and leaking reactor, raising the probability of a full-scale nuclear disaster, which could release radiation across the U.S. and even parts of Europe.

Just past noon in Japan, the Industrial Nuclear Safety Agency reported that the radioactive isotopes cesium and iodine had been detected by a monitoring station near the Fukushima plant. The facility has six reactors, three of them operating at the time of the earthquake. Two of these are overheating and Reactor 1 is leaking radioactive particles into the atmosphere.

The presence of these isotopes in air samples is a sure indicator of an uncontrolled chain reaction. Japanese nuclear engineers are explaining that overheated uranium rods seared through their metal casings, triggering the start of nuclear fission. The regulatory agency's statement contradicts the earlier claim of the plant’s operator, TEPCO, that all uranium rods were intact.

The afternoon explosion, which injured four workers, is hampering efforts by emergency workers to pump cold water into the reactor and release steam through safety valves. The internal steam pressure inside the reactor vessel is more than twice the approved level of the original design.

Truck-mounted generators have restored electrical power. The government has been frantically trying to locate robots to reopen the control room, which is now 1,000 times more radioactive than safe levels for humans. The cooling water is being provided by a common fire engine.

If temperatures and internal pressure cannot be significantly lowered soon, the likelihood of a fractured reactor barrier is increased. If the reactor shell cracks, the internal water will vaporize, creating conditions for uncontrolled fission and massive radioactive releases into the atmosphere.

Over the past 24 hours, the evacuation area for local residents has been widened from a diameter of three kilometers to 20 kilometers (12.4 miles). Over the same time period, outdoor radiation levels have risen from eight times higher than normal to 20 times higher, according to the monitoring station near Fukushima No.1.

Coming In Hot: Impact on North America

Panic is uncalled for, since cesium contamination poses a long-term rather than short-term threat, which can be reduced with timely countermeasures.

1. Pacific Jet Stream: In the spring season, the jet stream moves eastward from Japan toward the United States. Heated isotopes, riding on a cushion of steam and oceanic updrafts, will rise to the west-east jet stream at altitude 20,000 feet or higher. Areas of radioactive fallout are difficult to predict since these depend on local wind currents, temperatures, rainfall and other factors. The jet stream will cross the following states: California, Oregon, Montana, Idaho, Nevada, Colorado, Wyoming, Nebraska, the Dakotas, Iowa, Wisconsin, Illinois and possibly further depending on surface winds. Cesium can be expected to fall unevenly, so monitoring is vital to determine the long-term threat level.

2. Cesium Fallout: Dispersal in the jet stream will greatly dilute the concentration of radiation, but the long half-life of cesium will constitute a health threat to humans and animals. Following the Chernobyl disaster, much of Western Europe was cesium-contaminated. After Chernobyl, the Polish people were given potassium iodide tablets to block radioactive iodine-131 to prevent thyroid disorders, including cancer. Ukraine failed to this this, resulting in a spike in thyroid-related problems. Some countries banned the feeding of infants with breast milk, due to the concentration of radiation in human organs.

3. Cloud-seeding: Precipitation and atmospheric low pressure can force down airborne particles into the ocean. To be effective, a cloud-seeding program would have to be steadily maintained and conducted over a large area of the northwestern Pacific (just east of Japanese waters). The effort is daunting enough to require a multinational commitment of U.S., Russian, Japanese and Canadian air forces to detect radiation and spread pellets of cloud-seeding compounds. Once radioactive particles enter the fast-flowing jet stream, it will be well nigh impossible to contain the flow. Rainfall, natural or artificial, is unlikely to stop all radiation from crossing the Pacific but can lower the total volume.

4. Reactor Entombment: In event of a full-on core meltdown, entombment of a cracked reactor is necessary, as was done in Chernobyl. An out-of-control reactor will have to be encased by tons of concrete mixed with a neutron absorber like titanium dioxide. The process is slow and difficult requiring helicopter drops and high-pressure concrete pumps.

5. Herd Slaughter and Burial: Dispersed cesium is collected in the bodies of grazing animals and then concentrated in their milk and organs. In more affected areas of North America, a mass slaughter and burial of herding animals and wildlife will have to be methodically organized, as was done across Northern Europe following the Chernobyl disaster. Grain-fed animals must also be monitored for herd destruction if the grain crops were grown in contaminated soils.

Yoichi Shimatsu, former editor of the Japan Times Weekly, has covered the earthquakes in San Francisco and Kobe, participated in the rescue operation immediately after the Indian Ocean tsunami in 2004 and led the field research for an architectural report on structural design flaws that led to the tsunami death toll in Thailand.