Before today’s updates, we might return to an issue that has continued since mid-March…the possibility of a Zirconium fire in the spent fuel pools (SPF). Many reputable sources continue to mention the unlikely potential for Zirconium cladding catching on fire, and sources of questionable repute make it a factual possibility. After researching several metallurgical sites, we find the possible foundation of the issue. All of these knowledgeable sites say the same thing…in it’s solid, metallic form Zirconium is non-flammable. (The site referenced below has it all on one page.) Any metal, including steel, will burn at incredible temperatures in excess of 4,000oC (~7,500oF). The problem with it actually happening is reaching a temperature that extreme in some place other than a laboratory or a facility specifically designed to reach those temperatures. A nuclear power plant SPF is simply the wrong kind of facility, and it’s the wrong kind of Zirconium.

It seems the Zirconium fire possibility comes from the same confabulated kernel of truth that spawned the Zirconium explosion rumor/myth in March. If the Zirconium is powdered, it can burn at temperatures as low as 200oC. In a granular form (like sand), it can burn at ~500oC. But in a solid form (like nuclear fuel bundle cladding), it burns at a higher temperature than solid Aluminum (~4,000oC). For Zirconium metal, the boiling/burning temperature is 4,377oC. Decay heat levels in Fukushima’s SPFs at the moment of the tsunami would have taken at least 10 days of accelerated evaporation to completely uncover the stored fuel and leave it dry. (Necessary for any ignition). The fuel bundles at Fukushima would then have been in an open-air environment, where reaching 4,000oC is essentially impossible. In fact, it’s questionable that they could ever reach the Zirconium melting point of 1852oC.

Why so many highly regarded nuclear organizations continue to keep the Zirconium fire issue alive is a befuddling mystery.

See :; ESPI Metals; ESPI Corporation, Incorporated; Ashland, Oregon; January, 2008

Now, back to Japan and the Japanese Atomic Industrial Forum’s information…

  • The internal temperatures of RPVs #1, 2 & 3 remain stable, though the readings seem to fluctuate a few degrees C from day to day. All temperatures are consistently at or below 120oC.
  • A SPF cooling system for unit #2 has been completed and is being tested. Water from the pool is being sent through a heat exchanger outside the reactor building walls, where the water is cooled. The cooled water is then returned to the SPF. This is a relatively small cooling system and the cool-down will be slow.
  • TEPCO says they will have a sea-water “purification” system working by Thursday to remove the high contamination levels found just outside the unit #2 and 3 intake structure. This has been the location of highest radioactivity. The clean-up will be from waters inside the first ring of silt dams, installed last month. They expect the clean-up system will remove enough activity to stop the recent build-up outside the inner dam. It should be noted, the inner water’s 2,300-times-government-limit contamination reading from Monday has dropped to about 5 times the limit this morning. The sudden increase on Monday is attributed to the leak discovered, and stopped, on May 11.
  • Two Fukushima unit #1 control room operators have been discovered to have ingested sufficient radioactive material to expose them to greater than the 250 msv/yr emergency dose limit. Japan Times reports they were in the control room when the #1 upper refueling deck experienced its hydrogen explosion on March 12. It is unlikely any operating personnel would have been wearing face masks, at that point. Thus, they probably breathed in a high concentration of airborne activity from the explosion’s burst of contamination, swept into the control room through the ventilation ducting. JAIF continues that another 30 workers, also at the plant site on March 12, have internal contamination that will give them ~ 100msv exposures. As a result, the government has ordered TEPCO to immediately test more workers for internal radioactivity.It has taken way too long for this to be discovered and reported! TEPCO says the sensitive devices used to make these determinations were not available for use until March 22. That’s slow, but forgivable considering the monitoring locations were without power until then. Regardless, whole body scans should have started immediately on those who were on duty at the time of the explosion. Yet, these two operators were not scanned until mid-April, nearly a month after scans began. Why were they not the first in line, and why has it taken more than another month to get their scan results out?TEPCO is full of thin excuses. They say the actual “reading” of each person takes a “long time”, and then at least a week to verify the results. Plus, they originally had only four units available. (They now have nine counting those at Fukushima Daini)This writer had annual whole body counts in the late 1980s (required in US plants) which took less than 30 minutes for the scan itself, and the detailed read-out was ready within the hour. They could tell me whether or not I had a banana on my cereal that morning! The Japanese whole body counters could be lower-grade than those we used in the 1980s, but this is unlikely with one of the most electronically advanced nations on Earth. However, not examining the workers most-at-risk before examining others, is inexcusable!
  • On Tuesday, an “impact sound” emanated from a rubble pile adjacent to reactor building #4. A remote-controlled machine removing the rubble seems to have hit a buried oxygen tank and caused it to burst. No-one was hurt and no increases in airborne activity were detected.
  • Numerous parents in Fukushima Prefecture, living outside the no-entry zone, have sent their children to schools in other prefectures. The school-child exodus numbers about 10,000. The reported reason is fear of radiation. In addition, another 5,000 children have been enrolled in new schools inside Fukushima Prefecture, away from the higher contamination areas mapped out in April from airplane monitors. Those children who remain in their schools are being urged to wear long-sleeved shirts to accommodate parental fears of their kids getting Fukushima “fallout” on their skin.
  • The International Atomic energy Agency (IAEA) has submitted a preliminary report on their Fukushima investigation to the Japanese government. The report points out that “Japan” initially underestimated the impact of the tsunami on Fukushima Daiichi, but eventually took all conceivable and appropriate measures. The JAIF article summarizes, “It (the report) urges the government to correctly assess the risks of all natural disasters, and draw up protective measures in the design and operation of nuclear power plants. The report adds that Japan’s Nuclear and Industrial Safety Agency (NISA) should be independent and given a clear role based on IAEA standards, so it can respond appropriately to disasters.”
  • 59 evacuees from the no-entry zone have been allowed to re-enter and re-claim their automobiles. The cars were found to be free of contamination. As each day passes, more “clean” cars will be returned to their owners.
  • JAIF has confirmed the plans for financial compensation to companies and businesses proven to have lost income due to rumors concerning radiation. Public evacuees forced to leave the no-entry zone will also be compensated for “mental suffering”.

Now, from the rest of Japan…

  • NISA reports the slow, relatively small oil leak from units 5 & 6, which has gained some media attention since Monday, was completely contained within the break-walls of the “dedicated port of Fukushima Daiichi, NPS”. None of the oil has reached the open sea. This morning, TEPCO says the leak has stopped.
  • NHK World News and Kyodo News report the “opposition parties” (e.g. those not in government control) have submitted a “no-confidence motion” to the Lower House of Representatives. This means they have lost confidence in Prime Minister Kan and want the immediate resignation of his cabinet (and him). The House will formally vote on the motion Thursday. If it passes, prior governmental practice demands the resignation of the cabinet occur as soon as possible, followed by the Prime Minister. The opposition parties claim Kan’s responses to the quake/tsunami were inept and inadequate. It is somewhat surprising that several House members from Kan’s own party agree with the opposition and have signed the motion. In addition, former Democratic Party leader Ichiro Ozawa and former prime minister Yukio Hatoyama say they intend to vote in favor the motion. Ozawa says he feels Kan’s handling of the nuclear emergency has been poor, but he cannot formally vote since Kan recently asked for (an received) Ozawa’s resignation from Kan’s cabinet. Is Kan’s ship sinking? The opposition parties outnumber Kan’s DPJ party in the House, so the motion has to be taken seriously by everyone. Of course, Kan rejects the motion as something inappropriate at this point in time. By law, he can respond to the passed motion by dissolving the House and demanding a new, nation-wide election.Regardless, it seems to this writer that changing captains in the middle of a storm, even one demonstrated to be unworthy, is not the way to go.
  • Japan Times reports that Diva Soprano Anna Netrebko and lead tenor Joseph Calleja of the Metropolitan Opera have refused to go to Japan for the upcoming tour of Nagoya and Tokyo. They both cite fears of radiation from Fukushima. It is implied that they don’t trust the “official” reports that radiation levels have returned to normal in both cities. It doesn’t matter that opera mega-star Placido Domingo safely performed in Japan last month, either. The tour, the Met’s seventh in Japan, begins Saturday and runs through June 19. Is this yet another example of the Hiroshima Syndrome’s world-wide psychological impact? Of course it is!