Japanese engineer: ‘There was a nuclear explosion in Reactor 3 in addition to a hydrogen explosion’

By arevamirpal::laprimavera
12 December 2011 There are foreign nuclear experts who have said the explosion in Reactor 3 on March 14 at Fukushima I Nuclear Power Plant was a nuclear explosion. But this Japanese engineer and whistleblower at JNES (Japan Nuclear Energy Safety Organization) Setsuo Fujiwara says there were two explosions at Reactor 3: a hydrogen explosion, and a nuclear explosion at the Spent Fuel Pool. The following is my best-effort translation of the interview Fujiwara did with the SPA magazine, without detailed technical knowledge of nuclear physics, subject to revision. […] 「３号機の燃料プール内では、爆発が生じるまでに冷却水が少なくなり、ジルカロイ・水反応で水素が発生。上方の燃料被覆管が溶けて、中のペレットはブロック崩し状態。プール内が原子炉さながら、小出力で臨界状態となって水が沸騰したと思われます。そして、プール水面上方で水素爆発。その圧力で沸騰水中のボイド（水蒸気）が圧縮。ボイド反応度係数はマイナスなので、一気に核分裂の反応度が高まり、即発臨界の核爆発が起きた。３号機爆発のスローモーションビデオを観ると、爆発音が３回聞こえる。これが、水素爆発の後に核爆発が生じた証拠です」 “The amount of cooling water decreased in the Reactor 3 SFP prior to the explosion, and hydrogen was generated from the zircaloy-water reaction. The upper part of the cladding melted, and the pellets fell out and piled [at the bottom of the pool?]. Inside the SFP, it was like a nuclear reactor becoming critical, and the water boiled. Then there was a hydrogen explosion above the surface of the water in the SFP, and due to the pressure from the explosion, voids (steam bubbles) in the boiling water were compressed. The void coefficient was negative, so the reactivity of nuclear fission was suddenly heightened, resulting in a nuclear explosion from the prompt criticality. When you see the slow-motion video of Reactor 3’s explosion, you hear three explosive sounds. It is the evidence that the nuclear explosion occurred after the hydrogen explosion.” […]