Cross section generation strategy for advanced LWRs

B. Herman, E. Shwageraus, J. Leppänen, B. Forget

Research output: Book/ReportBook (author)

Abstract

A method for generating few-group homogenized cross sections using three-dimensional Monte Carlo assembly calculations is described and compared to a traditional two-dimensional assembly homogenization method. It is demonstrated that the traditional two-dimensional method of few-group homogenized cross section generation for full core analyses may not be sufficient for high conversion LWR designs. In these types of reactors, such as the Hitachi RBWR, separate fissile and blanket zones are required for breeding and for managing void reactivity feedback, resulting in highly axially-heterogeneous assemblies. In the two-dimensional calculation, each zone was decoupled from other zones by assuming zero net current boundary conditions. In the three-dimensional calculation, the presence of other axial zones that influence the generation of homogenized cross sections is explicitly captured. Differences in flux energy spectra were seen, leading to differences in 2-group homogenized cross sections of up to 50%. The differences in the homogenized parameters were highest in interface zones and near the top of the assembly due to the presence of an axial reflector and a high coolant void fraction. It was determined that these errors may be significant and propagate to the full core analysis of these types of advanced LWRs.
Original languageEnglish
Publication statusPublished - 2011
MoE publication typeC1 Separate scientific books

Publication series

SeriesINIS
NumberINIS-FR--13-0283
Volume44

Fingerprint

assembly
cross sections
voids
blankets
coolants
homogenizing
assemblies
reflectors
energy spectra
reactivity
reactors
boundary conditions

Keywords

  • bwr type reactors
  • computerized simulation
  • group constants

Cite this

Herman, B., Shwageraus, E., Leppänen, J., & Forget, B. (2011). Cross section generation strategy for advanced LWRs. INIS, No. INIS-FR--13-0283, Vol.. 44
Herman, B. ; Shwageraus, E. ; Leppänen, J. ; Forget, B. / Cross section generation strategy for advanced LWRs. 2011. (INIS; No. INIS-FR--13-0283, Vol. 44).
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Herman, B, Shwageraus, E, Leppänen, J & Forget, B 2011, Cross section generation strategy for advanced LWRs. INIS, no. INIS-FR--13-0283, vol. 44.

Cross section generation strategy for advanced LWRs. / Herman, B.; Shwageraus, E.; Leppänen, J.; Forget, B.

2011. (INIS; No. INIS-FR--13-0283, Vol. 44).

Research output: Book/ReportBook (author)

TY - BOOK

T1 - Cross section generation strategy for advanced LWRs

AU - Herman, B.

AU - Shwageraus, E.

AU - Leppänen, J.

AU - Forget, B.

PY - 2011

Y1 - 2011

N2 - A method for generating few-group homogenized cross sections using three-dimensional Monte Carlo assembly calculations is described and compared to a traditional two-dimensional assembly homogenization method. It is demonstrated that the traditional two-dimensional method of few-group homogenized cross section generation for full core analyses may not be sufficient for high conversion LWR designs. In these types of reactors, such as the Hitachi RBWR, separate fissile and blanket zones are required for breeding and for managing void reactivity feedback, resulting in highly axially-heterogeneous assemblies. In the two-dimensional calculation, each zone was decoupled from other zones by assuming zero net current boundary conditions. In the three-dimensional calculation, the presence of other axial zones that influence the generation of homogenized cross sections is explicitly captured. Differences in flux energy spectra were seen, leading to differences in 2-group homogenized cross sections of up to 50%. The differences in the homogenized parameters were highest in interface zones and near the top of the assembly due to the presence of an axial reflector and a high coolant void fraction. It was determined that these errors may be significant and propagate to the full core analysis of these types of advanced LWRs.

AB - A method for generating few-group homogenized cross sections using three-dimensional Monte Carlo assembly calculations is described and compared to a traditional two-dimensional assembly homogenization method. It is demonstrated that the traditional two-dimensional method of few-group homogenized cross section generation for full core analyses may not be sufficient for high conversion LWR designs. In these types of reactors, such as the Hitachi RBWR, separate fissile and blanket zones are required for breeding and for managing void reactivity feedback, resulting in highly axially-heterogeneous assemblies. In the two-dimensional calculation, each zone was decoupled from other zones by assuming zero net current boundary conditions. In the three-dimensional calculation, the presence of other axial zones that influence the generation of homogenized cross sections is explicitly captured. Differences in flux energy spectra were seen, leading to differences in 2-group homogenized cross sections of up to 50%. The differences in the homogenized parameters were highest in interface zones and near the top of the assembly due to the presence of an axial reflector and a high coolant void fraction. It was determined that these errors may be significant and propagate to the full core analysis of these types of advanced LWRs.

KW - bwr type reactors

KW - computerized simulation

KW - group constants

M3 - Book (author)

T3 - INIS

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ER -

Herman B, Shwageraus E, Leppänen J, Forget B. Cross section generation strategy for advanced LWRs. 2011. (INIS; No. INIS-FR--13-0283, Vol. 44).