Chernobyl by the Sea
The terrible accident at Chernobyl, triggered by an attempted test of the very conditions that came to pass in Fukushima loss of continuous electric power supply has been widely chalked up to that bad old Soviet technology, and therefore understood to be something that just wouldn't happen in a modern high-tech democracy.
Brushing away this terrible new disaster, in the land of the Prius, the Walkman, and the ductless inverter heat pump, should not be quite so pat.
Developed by cross-referencing point samples with weather modeling, the early estimates by ZAMG suggested iodine-131 releases comparable to 20% of the total amount released in the Chernobyl accident, and cesium-137 releases comparable to 50% of the total amount released in the Chernobyl accident just from the first four days of the Fukushima disaster which as of Friday, March 25, had been going on for 14 days.
Spreading contamination began to show up on Monday, March 14, when the U.S. Seventh Fleet reported that 17 members of three helicopter crews from the U.S. Ronald Reagan aircraft carrier, providing disaster assistance off the coast of Japan, returned with measurable radiation contamination and underwent decontamination procedures. Their aircraft also had measured radiation contamination and were washed down for decontamination. The radiation is believed to be from a plume of material released from the Fukushima Daiichi Power Plant.
The U.S. Navy ships relocated to avoid being directly downwind of the damaged plant. News media report that naval operations continue to work around areas of heightened radioactivity. On Tuesday, March 15, a no-fly zone with a 32-kilometer (20-mile) radius around the Fukushima Daiichi plant was established for commercial aviation.
A week later, on Tuesday, March 22, "Japan's science ministry [said] radiation exceeding 400 times the normal level was detected in soil about 40 kilometers (25 miles) from the troubled Fukushima Daiichi nuclear power plant." (NHK)
Radiation was measured on food products including milk and spinach grown at distances 30 kilometers (19 miles) and even father from the Fukushima nuclear plant, indicating contamination with radioactive materials.
On Wednesday, March 23, warnings on feeding tap water to infants were issued for Tokyo a metropolitan area with 35 million or more residents. That seemed to bring out a new round of placating and typically garbled messages from mainstream media on radiation units and relative exposures.
Daily updates in German from the Austrian weather agency ZAMG have included an animation of the emissions plume over time, winding out to sea, and sometimes curling back over the land, since the beginning of the disaster.
Thankfully for the mainland of Japan, and especially for the Tokyo area, the great majority of the Chernobyl-level of radioactive emissions from the Fukushima Daiichi plant so far have been carried out over the Pacific Ocean by favorable westward winds, and gradually diluted.
Beyond Three Mile Island
It was likely from the second day onward that Fukushima Daiichi was in the midst of a triple-Three-Mile-Island level of accident, but not until the ZAMG modeling results were released was there information to show something close to the level of a Chernobyl-type accident, with its widespread distribution of dangerous nuclear material.
Also late in the second week of the disaster, the exvacuation zone around the Fukushima plant was expanded from a radius of 20 kilometers (12 miles) to 30 kilometers (19 miles).
On Monday, March 21, as smoke was observed coming from reactor units #2 and #3, about 100,000 nuclear accident evacuees were reported as sheltering at 220 evacuation centers outside the 20-kilometer (12-mile) official evacuation area.
Thirty kilometers was also the evacuation radius around the Chernobyl plant, with 135,000 people displaced, and to this day the 30 kilometer radius marks Chernobyl's continuing exclusion zone.
The ongoing outcome of the triple-reactor nuclear accident will likely be determined by the degree of nuclear fuel damage probably already very significant at all three reactors at present, and how much further fuel melting in the reactors and fuel storage pools can be prevented by emergency cooling efforts.
The emergency cooling with seawater that was initiated during the first week of the disaster is an open-loop process (unlike normal closed-loop reactor cooling), and it creates heightened radiation releases because the water pumped into the reactor vessel is contaminated there, and then as the water boils, pressure has to be relieved, and the radioactive steam is vented into the atmosphere.
Furthermore, seawater is more corrosive than the purified water usually circulated through the reactor. In addition, under partial meltdown conditions, damaged fuel rods can include additional radionuclides generated in the uncontrolled nuclear reactions, and the nuclear material in damaged fuel rods is more likely to react with the coolant.
All these conditions make the ongoing venting to the atmosphere of steam from seawater cooling dangerously problematic. However, at this point, apparently only the emergency cooling with seawater is preventing further nuclear fuel core melting, and the possibility of a runaway meltdown, "recriticality," or "nuclear recursion," in any of the three most-crippled reactors.
The emergency procedure of cooling with salt water has apparently never been used before at a commercial reactor, over the 57-year history of the nuclear power industry (World Nuclear News (WNN)).
A long snorkel concrete pump truck was used successfully, for three hours late on Tuesday, March 22, to pump water into the fuel storage pool at reactor #4 (NHK).
Nuclear Crises Continuing
Fukushima Daiichi Nuclear Power Plant (Fukushima Number One) includes six boiling-water-type reactor units. Reactor #1, which suffered a partial core meltdown (NHK) and lost roof and wall cladding in a hydrogen explosion on Saturday, seawater is being used to cool the nuclear fuel.
NHK World (Japan) reported at the stricken Fukushima Daiichi reactor #3, fuel rods were exposed "2.2 meters [6.5 feet] above water for two hours". Any exposure of fuel rods is disastrous. As of Monday morning, seawater was also being used for emergency core cooling at Fukushima Daiichi reactor #3. Around 11:01AM om Monday, Tokyo time, a significant hydrogen explosion occurred at reactor #3 that destroyed much of the walls and roof of the containment building, with reports of additional worker casualties. The hydrogen explosion reportedly did not damage the reactor containment vessel.
Several people working on the Fukushima plants are reported to have radiation sickness, and the increasing radiation conditions have greatly increased the risk to plant workers. At least one nuclear plant worker is dead (WNN), perhaps from the explosion on Saturday that destroyed the roof of the reactor #1 building.
Fukushima Daiichi reactor units 4, 5, and 6 were already on scheduled shutdown at the time of the earthquake. These units were believed to be stable in shutdown mode, until fire erupted at reactor unit #4, and TEPCO acknowledged cooling problems in the onsite spent fuel storage pools.
At the Fukushima Daiichi Nuclear Power Plant reactor #2, cooling problems were reported off and on since Friday or Saturday. As of 5:00PM Monday in Japan, cooling had again become ineffective, fuel rods had become significantly exposed (80 cm (31 in.) or more), and around 8:00PM seawater injection to the reactor #2 was "resumed" (NHK). The crisis at this reactor is continuing.
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