Effect of fuel particles' size and position variations on multiplication factor in pebble-bed nuclear reactors
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L. Snoj
Abstract
The effect of TRISO particles' size variations and inter-particle distance on infinite multiplication factor (kinf) of a pebble bed reactor (PBR) is studied using MCNP code. It is observed that kinf decreases with increasing TRISO particles' size, mainly due to increased total particle surface leading to stronger resonance absorption. Negative temperature reactivity effect is observed at all particle sizes. The kinf increases strongly when particles form in clusters as the clusters behave as a single bigger particle. It is also observed that the white boundary condition is not an appropriate approximation of the unit-cell flux boundary condition in the calculations as it yields significantly higher values of kinf than periodic and reflective boundary conditions.
Kurzfassung
Der Einfluss von Änderungen der Größe von TRISO-Partikeln und der Abstände zwischen den Partikeln auf den Multiplikationsfaktor (kinf) eines Kugelhaufenreaktors wird mit Hilfe eines MCNP Codes untersucht. Man beobachtet, dass kinf mit steigender Größe der TRISO-Partikel sinkt, hauptsächlich wegen der wachsenden Teilchenoberfläche, die zu einer stärkeren Resonanzabsorption führt. Die negative Temperaturrückkopplung der Reaktivität wird bei allen Teilchengrößen beobachtet. Der Multiplikationsfaktor kinf steigt stark, wenn Partikel Cluster bilden, da sich die Cluster wie ein einziges großes Teilchen verhalten. Es wurde auch beobachtet, dass die „weiße“ Randbedingung bei den Berechnungen keine geeignete Näherung der „unit-cell flux“ Randbedingung ist, da sie zu wesentlich höheren Werten von kinf führt als periodische und reflektive Randbedingungen.
References
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© 2007, Carl Hanser Verlag, München
Artikel in diesem Heft
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- Effect of fuel particles' size and position variations on multiplication factor in pebble-bed nuclear reactors
- Axial flux harmonics affecting the parallel channel instabilities in boiling water reactors
- Uncontrolled withdrawal of a control rod without SCRAM
- Modelling of Carbon-14, Iodine-129 and Cesium-137 releases from near surface radioactive waste disposal and their impact on environment and humans
- Investigation of nuclear model predictions for proton induced reaction cross-sections up to 150 MeV
- The extension of the 2-D finite element/boundary element hybrid method to general multigroup neutron diffusion theory
- Extension of the HN method for solving radiation transfer problems in plane geometry for general anisotropic scattering
- The albedo problem for pure-triplet scattering
- Studies on the transmission and processing of pulse-shaped signals from nuclear radiation detectors using methods of systems theory
- The preignition problem in nuclear explosive devices (NEDs) for a sigmoidal Rossi-α and a high neutron background
- Comparison of economy and emissions of nuclear power plants and combined gas and wind electricity generators
Artikel in diesem Heft
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- Effect of fuel particles' size and position variations on multiplication factor in pebble-bed nuclear reactors
- Axial flux harmonics affecting the parallel channel instabilities in boiling water reactors
- Uncontrolled withdrawal of a control rod without SCRAM
- Modelling of Carbon-14, Iodine-129 and Cesium-137 releases from near surface radioactive waste disposal and their impact on environment and humans
- Investigation of nuclear model predictions for proton induced reaction cross-sections up to 150 MeV
- The extension of the 2-D finite element/boundary element hybrid method to general multigroup neutron diffusion theory
- Extension of the HN method for solving radiation transfer problems in plane geometry for general anisotropic scattering
- The albedo problem for pure-triplet scattering
- Studies on the transmission and processing of pulse-shaped signals from nuclear radiation detectors using methods of systems theory
- The preignition problem in nuclear explosive devices (NEDs) for a sigmoidal Rossi-α and a high neutron background
- Comparison of economy and emissions of nuclear power plants and combined gas and wind electricity generators
