JAEA to Recreate a Core Melt to Better Understand #Fukushima I NPP Accident

Japan Atomic Energy Agency (JAEA) of Monju fame (most recently with free video playback software download that infected the PC in the central control room at Monju) will conduct an experiment that creates a small-scale core melt (commonly referred to as "meltdown").

Let's see. JAEA had a fire at Monju, which they hid. They dropped the fuel handling machine in the reactor. There were so many irregularities that Nuclear Regulation Authority was recommending shutting down the organization, when the pro-nuclear Abe administration came in and pledged to continue fuel recycle using Monju operated by JAEA.

(I would be much more comfortable if it weren't JAEA who will be doing the experiment.)

From Yomiuri Shinbun (1/8/2014):

炉心溶融を実験で再現…原子力機構、事故対策へ

JAEA to recreate core melt in an experiment, [result] to be utilized in dealing with Fukushima I NPP accident

日本原子力研究開発機構は、東日本大震災の際に東京電力福島第一原子力発電所で起きた炉心溶融（メルトダウン）を再現する小規模実験を、新年度に行う。

Japan Atomic Energy Agency will conduct a small-scale experiment in the new fiscal year (that starts April 1, 2014) that will recreate a core melt that happened at Fukushima I Nuclear Power Plant after the March 11, 2011 earthquake/tsunami.

事故の際、核燃料の過熱や溶融がいつごろ、どのように進んだのかは、これまで限られたデータを基にコンピューター計算で推定されただけで、不明な点が多い。実際の核燃料を冷却水のない「空だき」で過熱させる実験により、機構は「事故で起きた現象を明らかにして、今後の原発の事故対策に役立てたい」と話している。

So far, the progression of core melt has only been simulated by computer models based on limited data, and there is much that are still unknown. By using an actual fuel rod and overheat it without coolant [water], JAEA hopes to "better understand what actually happened in the accident and utilize the knowledge gained from the experiment in dealing with the accident."

実験は、茨城県東海村にある原子炉安全性研究炉で行う。研究炉の中心部にステンレス製のカプセル（長さ１・２メートル）を入れ、ミニ燃料棒（同３０センチ）１本を水に触れないようにして収める。カプセルの周囲の核燃料から飛んでくる中性子によって、ミニ燃料棒の中のウランも核分裂し、２０００度以上の高温になって溶ける。

The experiment will be carried out in JAEA's Nuclear Safety Research Reactor (NSRR) in Tokai-mura in Ibaraki Prefecture. A stainless steel capsule (1.2 meter long) will be inserted in the center of the reactor, and a miniature fuel rod (30 centimeters long) will be placed in the capsule without touching water. Uranium in the miniature fuel rod will undergo nuclear fission as it is being hit by neutrons emitted from the nuclear fuels surround the capsule, causing the temperature to rise above 2,000 degrees Celsius and causing the fuel rod to melt. [See the diagram by Yomiuri. English labels are by me.]

機構によると、実際の原発で使う長さ約４・５メートルの燃料棒の束に比べて少量で、核分裂はすぐに止まり、溶けて数分後には冷えて固まるという。固まった燃料は分析した後、他の核燃料と同様に、敷地内のプールで冷やして保管する。

According to JAEA, since [the fuel rod to be used] is much smaller than 4.5 meter-long fuel rods used in a real nuclear power plant, nuclear fission will stop shortly, and the melted fuel will cool and solidify in a few minutes. The solidified fuel will be analyzed, and then stored in the pool on the premises with other nuclear fuels.

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