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In Japan’s recent devastating earthquake and tsunami, the Fukushima Dai-Ichi nuclear plant structures remarkably survived the 9.0 quake intact, but suffered major damage when the tsunami destroyed external electrical transmission.
It also topped the seawall and inundated the backup diesel generators that power pumps for cooling water to the cores and adjacent spent fuel storage pools.
It is a severe loss of coolant event. The frantic reporting is reminiscent of Three Mile Island – inflated and misinterpreted.
It is hard to separate the facts from the assertions and the media are not helping, but with each passing day more information relevant to the outcome emerges and the hand wringing of previous days lessens.
The reactors shut down automatically when the quake struck so there is no fission heat involved. However, decay of fission products continues to produce a little less than a tenth of the heat of an operating reactor.
Cooling is crucial and the problem faced by the Japanese is cooling the reactor cores and the newer spent fuel in the storage pools. New fission heating is not expected now.
Because the tsunami also damaged the fresh water supply, the Japanese had no choice but to attempt cooling with seawater. That step ruined the reactor cores but averted most of the heat damage. The situation improves by the day and it appears that cooling will be restored.
Hydrogen explosions have occurred, 137-cesium and,131-iodine have been detected around reactor units one through four, resulting from intentional venting to relieve strain on containment. No massive radiation releases have occurred, containment appears to remain intact, and nobody has been killed.
In the worst case, the reactor cores will melt but remain contained without massive release of a radioactive plume.
Residual heat in an uncooled but shut down reactor is enough to melt the core.
The Three Mile Island core melted, the containment held, no significant radiation was released, and no one was injured or killed--not even a grasshopper. The search for cesium at Three Mile Island was intense.
Finally, a pike from the Susquehanna River gave evidence of 134- and 137-cesium but it turned out to be from a nine-month-old Chinese atmospheric weapons test, not from Three Mile Island.
The story illustrates the incredible sensitivity of detection instruments.
The information that “radiation” has been detected on returning commercial aircraft, dutifully reported by the distracted press, also illustrates the remarkable sensitivity of detection devices, as does reporting of 131-Iodine in local milk, and activity on leafy vegetables.
Little information on amounts or identity of contributing nuclides escaping from the reactor complex is available except that measured spikes of radioactivity exceed accepted emergency annual worker exposure limits fivefold (500 Millisieverts.) That value suggests that relatively small amounts have been released consistent with the notion that it comes from intentional venting and not a breach.
To put the event in perspective, the four reactor cores and associated spent fuel pools are being stabilized, iodine and cesium releases are relatively small but indicate damage to the reactor cores, exposures of recovery personnel are low, and there have been no fatalities.
Thus, Fukushima Dai-Ichi is worse than Three Mile Island, but far, far less serious than Chernobyl.
The event is inconsequential by comparison with the awful calamity that has befallen the Japanese people, and eventually someone should take the melodramatic media to task for misplaced priorities that virtually ignore the genuine tragedy.
Don Petersen and Bill Stratton are retired from LANL and write for the Los Alamos Education Group.