FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W53917076> ?p ?o ?g. }

• W53917076 abstract "The objective of this thesis, which in clearly inspired by an framework, is to try and narrow the gap between theoretical neutron modelling and application in the context of nuclear reactor design. This thesis is divided into three main chapters, preceded by a general overview. This structure reflects the three main topics which were chosen for this research project. The first topic develops the Spectral Element Method (SEM) approach and its use in conjunction with transport approximations. As it is documented in the specialized numerical analysis handbooks and in previous works by the author, the method has an excellent convergence rate which outperforms most classical schemes, but it has also some important drawbacks which sometimes seem to discourage its use for linear transport problems applied to nontrivial benchmarks. In order to elaborate the methodology of the specific problems encountered in reactor physics, three aspects are addressed looking for improvements. The first topic analyzed is related to the convergence order, whose value is less straightforward to define a priori by means of functional analysis than other numerical schemes. The adjective spectral refers in fact to the maximum order claimed, exponential with respect to the average size of the mesh. A comprehensive set of convergence tests is carried out applying SEM to a few transport models and with the aid of manufactured solutions, thus isolating the numerical effects from the deviations which are due only to modelling approximations. The hypothesis of grid conformity is also relaxed, replacing the classical Galerkin variational formulation with the Discontinuous Galerkin theory, characterized by a more flexible treatment of the mesh interfaces; this scheme allows local grid refinement and opens the way, in perspective, to mesh adaption. Finally, a simple and sufficiently flexible technique to deform the boundaries of each mesh is introduced and applied, in order to adapt the grid to curved geometries. In this way, the advantages of SEM can be applied to a vast class of common problems like lattice calculations. Moreover, thanks to a change of the basis functions used in SEM, it is possible to obtain elements with three sides (straight or deformed), that are a typical war horse of the Finite Element approach. The second topic is essentially devoted to the most industrial part of the thesis, developed entirely during the stay of the author in the AREVA NP headquarters in Paris. In AREVA, and in all other nuclear engineering enterprises, neutron diffusion is still the preferred neutronic model for full-core studies. Better approximations are reserved for library preparation, fuel studies and code validation, none of these being typically too much time or budget-constrained. Today needs start to require a certain level of improvement also in full-core analyses, trying to fitly model localized dis-homogeneities and reduce the penalizing engineering margins which are taken as provisions. On the other hand, a change in the model does not mean only an effort to write a new code, but has huge follow-ups due to the validation processes required by the authorities. Second-order transport may support the foreseen methodology update because it can be implemented re-using diffusion routines as the computational engine. The AN method, a second-order approximation of the transport equation, has been introduced in some studies, and its effect is discussed. Moreover, some effort has been reserved to the introduction of linear anisotropy in the model. The last topic deals with ray effects; they are a known issue of the discrete ordinate approach (SN methods) which is responsible for a reduction in the accuracy of the solution, especially in penetration problems with low scattering, like several shielding calculations performed for operator safety concerns. Ray effects are here characterized from a formal point of view in both static and time dependent situations. Then, quantitative indicators are defined to help with the interpretation of the SN results. Based on these studies, some mitigation measures are proposed and their efficacy is discussed" @default.
• W53917076 created "2016-06-24" @default.
• W53917076 creator A5044776368 @default.
• W53917076 date "2014-01-01" @default.
• W53917076 modified "2023-09-23" @default.
• W53917076 title "Numerical Methods for Neutron Transport Calculations of Nuclear Reactors" @default.
• W53917076 doi "https://doi.org/10.6092/polito/porto/2561774" @default.
• W53917076 hasPublicationYear "2014" @default.
• W53917076 type Work @default.
• W53917076 sameAs 53917076 @default.
• W53917076 citedByCount "0" @default.
• W53917076 crossrefType "dissertation" @default.
• W53917076 hasAuthorship W53917076A5044776368 @default.
• W53917076 hasConcept C111472728 @default.
• W53917076 hasConcept C121332964 @default.
• W53917076 hasConcept C121864883 @default.
• W53917076 hasConcept C126255220 @default.
• W53917076 hasConcept C127162648 @default.
• W53917076 hasConcept C135628077 @default.
• W53917076 hasConcept C138885662 @default.
• W53917076 hasConcept C151730666 @default.
• W53917076 hasConcept C152568617 @default.
• W53917076 hasConcept C162324750 @default.
• W53917076 hasConcept C186899397 @default.
• W53917076 hasConcept C199343813 @default.
• W53917076 hasConcept C2777303404 @default.
• W53917076 hasConcept C2777686260 @default.
• W53917076 hasConcept C2779343474 @default.
• W53917076 hasConcept C28826006 @default.
• W53917076 hasConcept C31258907 @default.
• W53917076 hasConcept C33923547 @default.
• W53917076 hasConcept C41008148 @default.
• W53917076 hasConcept C50522688 @default.
• W53917076 hasConcept C57869625 @default.
• W53917076 hasConcept C62520636 @default.
• W53917076 hasConcept C66963500 @default.
• W53917076 hasConcept C71924100 @default.
• W53917076 hasConcept C75553542 @default.
• W53917076 hasConcept C86803240 @default.
• W53917076 hasConcept C92244383 @default.
• W53917076 hasConcept C97355855 @default.
• W53917076 hasConceptScore W53917076C111472728 @default.
• W53917076 hasConceptScore W53917076C121332964 @default.
• W53917076 hasConceptScore W53917076C121864883 @default.
• W53917076 hasConceptScore W53917076C126255220 @default.
• W53917076 hasConceptScore W53917076C127162648 @default.
• W53917076 hasConceptScore W53917076C135628077 @default.
• W53917076 hasConceptScore W53917076C138885662 @default.
• W53917076 hasConceptScore W53917076C151730666 @default.
• W53917076 hasConceptScore W53917076C152568617 @default.
• W53917076 hasConceptScore W53917076C162324750 @default.
• W53917076 hasConceptScore W53917076C186899397 @default.
• W53917076 hasConceptScore W53917076C199343813 @default.
• W53917076 hasConceptScore W53917076C2777303404 @default.
• W53917076 hasConceptScore W53917076C2777686260 @default.
• W53917076 hasConceptScore W53917076C2779343474 @default.
• W53917076 hasConceptScore W53917076C28826006 @default.
• W53917076 hasConceptScore W53917076C31258907 @default.
• W53917076 hasConceptScore W53917076C33923547 @default.
• W53917076 hasConceptScore W53917076C41008148 @default.
• W53917076 hasConceptScore W53917076C50522688 @default.
• W53917076 hasConceptScore W53917076C57869625 @default.
• W53917076 hasConceptScore W53917076C62520636 @default.
• W53917076 hasConceptScore W53917076C66963500 @default.
• W53917076 hasConceptScore W53917076C71924100 @default.
• W53917076 hasConceptScore W53917076C75553542 @default.
• W53917076 hasConceptScore W53917076C86803240 @default.
• W53917076 hasConceptScore W53917076C92244383 @default.
• W53917076 hasConceptScore W53917076C97355855 @default.
• W53917076 hasLocation W539170761 @default.
• W53917076 hasOpenAccess W53917076 @default.
• W53917076 hasPrimaryLocation W539170761 @default.
• W53917076 hasRelatedWork W1505328129 @default.
• W53917076 hasRelatedWork W1527961967 @default.
• W53917076 hasRelatedWork W1980756889 @default.
• W53917076 hasRelatedWork W1998100805 @default.
• W53917076 hasRelatedWork W20143435 @default.
• W53917076 hasRelatedWork W2023233205 @default.
• W53917076 hasRelatedWork W2030127415 @default.
• W53917076 hasRelatedWork W2036617335 @default.
• W53917076 hasRelatedWork W2136173462 @default.
• W53917076 hasRelatedWork W2288846939 @default.
• W53917076 hasRelatedWork W2324337765 @default.
• W53917076 hasRelatedWork W2416779119 @default.
• W53917076 hasRelatedWork W2463714931 @default.
• W53917076 hasRelatedWork W2583186796 @default.
• W53917076 hasRelatedWork W2600217100 @default.
• W53917076 hasRelatedWork W2985019967 @default.
• W53917076 hasRelatedWork W3023143511 @default.
• W53917076 hasRelatedWork W329794753 @default.
• W53917076 hasRelatedWork W591578596 @default.
• W53917076 hasRelatedWork W981857033 @default.
• W53917076 isParatext "false" @default.
• W53917076 isRetracted "false" @default.
• W53917076 magId "53917076" @default.
• W53917076 workType "dissertation" @default.