Nuclear Journal on ‘Fukushima Plutonium Effect’: Melting MOX fuel may lead to neutron flux blow-up — ‘Surprisingly’ there’s absolutely no reference data in any scientific literature

Published: January 6th, 2014 at 10:06 am ET


Fukushima Plutonium Effect and Blow-Up Regimes in Neutron-Multiplying Media, World Journal of Nuclear Science and Technology (2013) h/t majia:

Fukushima Plutonium Effect & Blow-Up Regimes in Neutron-Multiplying Media

It is shown that the capture and fission cross-sections of 238U and 239Pu increase with temperature within 1000 K – 3000 K range, in contrast to those of 235U, that under certain conditions may lead to the so-called blow-up modes, stimulating the anomalous neutron flux and nuclear fuel temperature growth. […]

It is known that after the loss of coolant at three nuclear reactors during Fukushima nuclear accident its nuclear fuel melted. It means that the temperature in the active zone at some moments reached the melting point of uranium-oxide fuel [the third block partially used MOX-fuel enriched with plutonium], i.e. ~3000˚C. Surprisingly enough, scientific literature today contains absolutely no either experimental or even theoretically calculated data on behavior of the 238U and 239Pu capture and fission cross-sections depending on temperature at least in 1000˚C – 3000˚C range. At the same time there are serious reasons to believe that the cross section values of the mentioned elements increase with temperature. […] it is very important to know the anomalous temperature behavior of 238U and 239Pu capture and fission cross-sections, and furthermore it becomes critically important to know their influence on the heat transfer kinetics, since it may become a reason of the positive feedback (PF) with neutron kinetics leading to undesirable solution stability loss (the nuclear burning wave) as well as to a trivial reactor runaway with a subsequent nontrivial catastrophe. A special case of PF is a non-linear PF, which leads to the system evolution in so-called blow-up mode, or in other words, in such a dynamic mode when one or several modeled values (e.g. temperature and neutron flux) grows to infinity at a finite time. In reality, a phase transition is observed instead of the infinite values in this case, and this can in its turn become a first stage or a precursor of the future technogenic disaster. […]

One of the causes of a possible fuel temperature growth may lie, for instance, in a deliberate or spontaneous coolant loss, analogous to what happened during the Fukushima nuclear accident. […] the coolant loss may become a cause of the nonlinear heat source formation in the nuclear fuel, and consequently emergence of the mode with the temperature and neutron flux blow-up. In our opinion, the preliminary investigation of the heat transfer equation with nonlinear heat source points to an extremely important phenomenon of the anomalous of the temperature and neutron flux blow-up modes behavior. […]

Full journal article here

See also:  Study: Evidence of "uncontrollable nuclear reaction" at Fukushima after 3/11 -- "Emerged criticality" supported by data (PHOTOS)

And: New Book: Nuclear explosion may have occurred at Fukushima Unit 3 after 'supercritical condition' -- Sudden increase in plutonium, uranium recorded by U.S. at several EPA stations

And: L.A. Times: Speculation that "supercritical fission event" occurred at Fukushima reactor irradiating plutonium, says nuclear expert -- Explosion so massive investigators found fuel rod fragments a mile away

Published: January 6th, 2014 at 10:06 am ET


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