Report on neutron beams — Has a reactor at Fukushima gone “critical”?

Published: March 30th, 2011 at 5:18 pm ET
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Has Fukushima’s Reactor No. 1 Gone Critical?, Time Magazine blog, March 30, 2011:

[Emphasis Added]

On March 23, Dr. Ferenc Dalnoki-Veress, a Research Scientist at the Monterey Institute of International Studies saw a report by Kyodo news agency that caught his eye. It reported that Tokyo Electric Power Company (TEPCO) had observed a neutron beam about 1.5 km away from the plant.  Bursts of neutrons in large quantities can only come from fission so Dalnoki-Veress, a physicist, was faced with an alarming possibility: had portions of one of Fukushima’s reactors gone critical?

To nuclear workers, there are few events more fearful than a criticality accident. In such a scenario, the fissile material in a reactor core–be it enriched uranium or plutonium–undergoes a spontaneous chain reaction, releasing a flash of aurora-blue light and a surge of neutron radiation; the gamma rays, neutrons and radioactive fission products emitted during criticality are highly dangerous to humans. …

Dalnoki-Veress did not see any further reference to a neutron release. But two days after the Kyodo agency report, on March 25, TEPCO made public measurements of different isotopes contributing to the extremely high measured radioactivity in the seawater used to cool reactor No 1. Again, a piece of the data jumped out at Dalnoki-Veress: the high prevalence of the chlorine-38 (CL-38) isotope. CL-38 has a half-life of 37 minutes, so would decay so rapidly as to be of little long-term safety concern. But it’s very presence troubled Dalnoki-Veress. Chlorine-37 (CL-37) is part of natural chlorine that is present in seawater in the form of ordinary table salt. In order to form CL-38, however, neutrons must interact with CL-37. Dalnoki-Verress did some calculations and came to the conclusion that  the only possible way this neutron interaction could have occurred was the presence of transient criticalities in pockets of melted fuel in the reactor core. …

Read the Time report here.

Read Dalnoki-Veress’ report here.

Published: March 30th, 2011 at 5:18 pm ET
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10 comments to Report on neutron beams — Has a reactor at Fukushima gone “critical”?

  • Slick Vick

    Yep… and you’re not going to hear about this on the news..


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  • xdrfox

    He said it in the Plural !


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  • Move along Nothing to see here American Idol will start in five minutes.


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  • jimstewart

    4/8/2011 I saw a ethereal blue flash in the distance during the footage on the 7.1 Aftershock. It was unmistakable. But no mention so far? This was on TV about 2 hours ago. The filming location was probably in tokyo, the flash was very far off but very massive.


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  • Cyclops2

    I do not hear to much from the Nukie Lovers anymore. Maybe they do not like having small dirty Atomic Bombs going off in the safe G E reactors ?

    Get used to that Blue Light.

    I hope a completly melted down fuel pile does not do a big dirty A bomb in Japan.

    The real Baddy, is the HUGE Community Fuel Dump.


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  • SteveMT

    These neutron beams seen at Fukushima on 3/23 were indeed true, based on recent disclosures. “Did a Reactor go critical?” is now a rhetorical question times THREE.


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    • Can we ever expect “gravitas” in Governments, news agencies, nuclear & utility personnel or just plain “Joe Citizen” to grab this festering carbuncle by the short hairs & get some coordinated action started??


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    • Dbug

      Containment steel stops neutrons. That’s why it is so thick. Neutrons are normal in operation. It would have had to be a fuel pond, probably when water with no boric acid went in (boosts reaction) hot cladding made the hydrogen which exploded momentarily forcing a couple of the hotter more recently used assemblies close together (maybe some that had pellets packed differently due to damage). The sudden energy increase from critically would almost instantly making a huge steam burst pushing the fuel back apart. Criticality should also stop with the water gone, even bubbles reduce it. So it was over in a flash.

      In an improperly designed reactor an excessive surge can make a powerful shockwave of steam.
      While not an atomic explosion it still packs a punch. Read about the 1961 accident where a little 26,000 pound experimental reactor jumped 9 feet in the air. They learned quite a bit from that.

      http://wikimedia.org/wikipedia/en/wiki/SL-1


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