As reported in an earlier post some evidence emerging from few sources has lead experts to speculate that the reactor core in Unit 1 is still undergoing periodic Nuclear Fission.
Today Tokyo Electric Power Co. announced they are to inject nitrogen into reactor unit 1 at the crippled Fukushima Daiichi nuclear power complex, aiming to reduce the risk of a hydrogen explosion.
The nitrogen, is expected to be injected into the containment vessel of unit 1 reactor. The process is expected to take several days. However Hidehiko Nishiyama, government’s nuclear agency spokesman denied there is an immediate danger of explosion.
What make experts think Unit 1 may have become critical again?
Data released by TEPCO the plant operator indicates that although Fukushima Unit 1 was shut down during the March 11 earthquake, it appears to have “gone critical” again without human intervention. The detection of short-lived radioactive isotopes, substantiates the existence of this inadvertent criticality.
When Uranium atom splits, it also produces 2 Neutrons, those hit the next Uranium atom and causes it to split and on and on. That is called ‘chain reaction’. So when Neutrons are present, it indicates a chain reaction in a nuclear reactor.
On the 23 of March The Kyodo news published an item titled “Neutron Beam observed 13 times at crippled Fukushima nuke plant” It said: “The measured neutron beam may be evidence that uranium and plutonium leaked from the plant’s nuclear reactors and spent nuclear fuels have discharged a small amount of neutron beams through nuclear fission.”
Last week a reputable scientific paper was published on Japanfocus.org titled “What Caused the high Cl-38 Radioactivity in Fukushima Daiichi Reactor #1?” Where it discuses the discovery of an isotope called Chlorine-38, which does not exist in nature.
Chlorine-38 is created from Chlorine-37 absorbing a Neutron. Chlorine-37 is present in sea water and sea water has been used inside the reactors in an attempt to cool it. The paper suggests that nuclear chain reaction with sea water was responsible for the Chlorine-38 isotope found.
On the 1st of April, TEPCO the plant operator published it’s own report where they presented that the isotope Tellurium 129 was found in Fukushima unit 1. According to Arnold Gundersen A former nuclear industry senior vice president, with 39-years of nuclear power engineering experience, Tellurium 129 has 70 minute half life and that can only exist if Nuclear Fission is still going on. This isotope decays very quickly and should not have been found had the reactor has been shut down. The report also indicate 10 times higher levels of iodine 131 in Unit 1 compared with measurements in Unit 2 and 3.
KyodoNews reports today “A seawater sample taken near reactor No. 2 water intake on Saturday, showed a radioactive iodine-131 concentration of 7.5 million times the maximum level permitted under law, or about 300,000 becquerels per cubic centimeter.”