The Development of a Nodal Method for the Analysis of PWR Cores with Advanced Fuels
Author(s)
Hall, Sheldon
Type
Thesis
Abstract
This thesis outlines the development of a nodal method with the purpose of addressing difficulties
encountered in the modelling of advanced fuels. The standard calculational route used when
modelling a Uranium (U) fuelled Pressurised Water Reactor (PWR) is not accurate enough to
analyse a PWR containing U and Plutonium (Pu). This is because the assumptions made
when developing the standard route are not necessarily representative of situations involving
advanced fuels.
To address some of these poor assumptions a nodal method has been developed which can
solve the SPN equations in multiple energy groups. The SPN equations are an asymptotic
approximation of the full neutron transport equation, and as such will include more physical
effects than the neutron diffusion equation. The theory behind the development of this nodal
method is outlined in this thesis along with an extensive set of benchmark tests for verification
of the method. It is found that through a similarity transformation of the determining equations,
existing nodal diffusion solvers can obtain solutions to the SPN equations without any
approximations.
Previously EDF Energy have developed an embedded methodology to address the shortcomings
of the standard calculational route. This procedure solves the diffusion equation in greater detail
on local sub-meshes in order to correct the standard 2 group nuclear data, and reduces the pin
power errors by ≈ 50% by capturing spectral effects on the interface between two significantly
different fuel types. In this thesis the incorporation of the SPN nodal method into the embedded
methodology is described.
A small light water reactor benchmark is solved to test the accuracy of the embedded methodology
combined with the SPN nodal method. It is concluded that similar accuracy to diffusion
is attained with the SPN equations. This is because the homogenisation procedure produces
an error larger than the improvements due to the use of the SPN equations. To address the
limitations discovered in this thesis future work is proposed based on the author’s experience
of research in the area.
encountered in the modelling of advanced fuels. The standard calculational route used when
modelling a Uranium (U) fuelled Pressurised Water Reactor (PWR) is not accurate enough to
analyse a PWR containing U and Plutonium (Pu). This is because the assumptions made
when developing the standard route are not necessarily representative of situations involving
advanced fuels.
To address some of these poor assumptions a nodal method has been developed which can
solve the SPN equations in multiple energy groups. The SPN equations are an asymptotic
approximation of the full neutron transport equation, and as such will include more physical
effects than the neutron diffusion equation. The theory behind the development of this nodal
method is outlined in this thesis along with an extensive set of benchmark tests for verification
of the method. It is found that through a similarity transformation of the determining equations,
existing nodal diffusion solvers can obtain solutions to the SPN equations without any
approximations.
Previously EDF Energy have developed an embedded methodology to address the shortcomings
of the standard calculational route. This procedure solves the diffusion equation in greater detail
on local sub-meshes in order to correct the standard 2 group nuclear data, and reduces the pin
power errors by ≈ 50% by capturing spectral effects on the interface between two significantly
different fuel types. In this thesis the incorporation of the SPN nodal method into the embedded
methodology is described.
A small light water reactor benchmark is solved to test the accuracy of the embedded methodology
combined with the SPN nodal method. It is concluded that similar accuracy to diffusion
is attained with the SPN equations. This is because the homogenisation procedure produces
an error larger than the improvements due to the use of the SPN equations. To address the
limitations discovered in this thesis future work is proposed based on the author’s experience
of research in the area.
Date Issued
2013
Date Awarded
2013-05
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Pain, Christopher
Eaton, Matthew
Sponsor
EDF Energy (Firm) ; Engineering and Physical Sciences Research Council
Publisher Department
Earth Science and Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Engineering Doctorate (EngD)