The nature of two explosions that were witnessed within 3 s at the Chernobyl-4 reactor less than a minute after 21:23:00 UTC on April 25, 1986, have since then been the subject of sprawling interpretations. This paper renders the following hypothesis. The first explosion consisted of thermal neutron mediated nuclear explosions in one or rather a few fuel channels, which caused a jet of debris t...

For either nuclear fusion or generation IV fission reactors to be viable as a commercial energy source the decommissioning and waste disposal solutions must considered during design. A multi-step simulation process combining Monte Carlo Neutron Transport simulations with inventory have been performed estimate activation of steels in key reactor components European Sodium-cooled fast Reactor (ES...

The primary goal of this work is to study the feasibility of designing molten salt reactors to be critical when fed with, and only with the transuranium isotopes (TUS) and long lived fission products produced in LWRS. Another goal is to estimate the transmutation characteristics which might be attainable from such a Molten Sal t Transmuting Reactor (MSTR). Both moderated and unmoderated MSTR sy...

The most important target of the concept “sustainability” is to achieve fairness between generations. Its expanding interpolation leads to achieve fairness within a generation. Thus, it is necessary to discuss the role of nuclear power from the viewpoint of this definition. The history of nuclear power has been the control of the nuclear fission reaction. Once this is obtained, then the economy...

A reliable and validated nuclear database is required for the design of a fusion reactor. Neutrons produced by the fusion reactions between deuterium and tritium have a very peaked energy spectrum at 14 MeV, requiring a substantial extrapolation with respect to the database made available from fission studies. The correct evaluation of shielding properties, damage, nuclear heating and of tritiu...

Sensitivity analysis studies the effect of a change in given parameter to response function system under investigation. In reactor physics, this usually translates into study how cross sections and fission spectrum modifications affect value multiplication factor, delayed neutron fraction or void coefficient for example. Generalized Perturbation Theory provides useful tool assessment adjoint we...

The safety report of the TRIGAMark II reactor in Vienna includes three accident scenarios and their deterministic dose consequences to the environment. The destruction of the cladding of the most activated fuel element, the destruction of all fuel elements and a plane crash were considered scenarios in that report. The calculations were made in 1978 with the software program named STRISK. In th...

The Generation IV Pebble Bed Modular Reactor (PBMR) is being considered as a promising concept to produce electricity or process heat with high efficiencies and unique safety features. The PBMR is a high-temperature, helium-cooled, graphite moderated reactor. The fuel elements consist of 6 cm diameter spherical graphite “pebbles” containing each thousands of uranium dioxide microspheres. As the...

Reactor noise, caused both by the probabilistic nature of the fission chains and external reactivity noises, is one of the basic topics in nuclear science and engineering, both in theory and practice. Modeling reactor noise (and neutron flux fluctuation in general) is traditionally performed by two main approaches: the stochastic transport equation for the probability generating function and th...

Uranium contains only one naturally occurring isotope, 235U, which will sustain a nuclear chain reaction using normal water to moderate and reflect neutrons. At present, this isotope is present in low abundance (0.72%), requiring enrichment to 3% or greater for effective use in commercial nuclear reactors. Two billion years ago, however, the natural abundance of 235U was approximately 3%. Evide...