Abstract
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. Some features of the blow-up regimes in neutronmultiplying media are discussed.
Highlights
It is known that after the loss of coolant at three nuclear reactors during Fukushima nuclear accident its nuclear fuel melted
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
Capture and fission cross-sections, and it becomes critically important to know their influence on the heat transfer kinetics, since it may become a reason of the positive feedback2 (PF) with neutron kinetics leading to undesirable solution stability loss as well as to a trivial reactor runaway with a subsequent nontrivial catastrophe
Summary
It is known that after the loss of coolant at three nuclear reactors during Fukushima nuclear accident its nuclear fuel melted. At least we may point, for example, to the qualitative estimates by Ukraintsev [1], Obninsk Institute of Atomic Energetics (Russia), that confirm the possibility for 239Pu cross-sections growth in 300 ̊C - 1500 ̊C range Such anomalous temperature dependence of 238U and 239Pu capture and fission cross-sections may change the neutron and heat kinetics of nuclear reactors drastically. It is very important to know the anomalous temperature behavior of 238U and 239Pu. capture and fission cross-sections, and 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. Investigation of the temperature dependence of 238U and 239Pu capture and fission cross-sections in 300 ̊C 3000 ̊C range, and correspondingly, the heat transfer kinetics and its influence on neutron kinetics in TWR, is the main goal of the present paper
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