Nuclear reactor safety: Multiplicity Distribution of Prompt Neutron Fission, Frehaut and Terrel Comparison

Fabrice Pelestor Université de Toulon Ingénieur atomicien (diplômé de l’INSTN) Ingénieur mécanicien énergéticien (diplômé de l’ENSIMEV) Mathématiques spéciales (Lycée Dumont D’Urville)

ABSTRACT : multiplicity of neutrons when a fission occur has probability laws given by two authors, Terrel and Frehaut. This intrinsic random phenomena can have important implications on nuclear safety (when a reactor start, there is, then, for example, a certain probability that the reactor may go beyond prompt critical before any neutron signal is detected (Bell & Glasstone, Nuclear Reactor Theory, ed Van Nostrand, 1970,Reinhold, page 36). Its study is so important. I show this study must be completed.

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I) Introduction : fluctuations and Boltzmann equation

Man use currently chemical energy since many years, 500 000 for fire, without any bigs problems. Even if sometimes this dragon escape from its hands, the damages aren’t too excessive. Nuclear energy is only in use since an instant, opposite to the fire. But its power is more strong, many order of scale. So, an accident can injure millions peoples. If we want to use safety for thousands years this splendid energy, it is necessary to study it very carefully in all its aspects, without taboos. The simulation of start of a nuclear engine turns aside from the beaten track. I want to say there is not only the classical Boltzmann equation. Of course it’s a very important equation, but it must not mask underlying phenomenas, radio active behaviour of fission, which are of greatest important, particularly in this phase. Indeed, the radio actives phenomenas have intrinsics uncertains (for don’t say random) behaviours. This behaviour is taking into account by probabilities laws. The determinist Boltzmann equation use, in classical neutronic (in classical statistic mechanic too), cross sections as a traduction of this «