Background-Cross-Section-Dependent Subgroup Parameters

Yamamoto, Tadahiro

doi:10.3327/jnst.40.370

Cited by 6 publications

(7 citation statements)

References 8 publications

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“…(8) and (9) It may be worth noting that the 'plus terms' h t n i uþ appear only at relatively high order of power series in Eq. (8): this result is understood more easily if Eqs. (5) are multiplied by 0 N in advance and shown that the 'plus terms' are existent only in high order terms in the both equations.…”

Section: A General Comparison Of Fitting Methods and The Moment Mementioning

confidence: 86%

“…(8) and (9) does not directly appear in the actual derivation of the parameters in the fitting and the moment method. Let us look into the derivation scheme of the two methods.…”

Section: More Detailed Comparisonmentioning

confidence: 99%

“…8) The direct application of the formula can produce the 'best' definition of the subgroup parameters for a given set of subgroup boundaries, i.e., the lower and upper boundaries of the total cross sections of each subgroup. At the same time, the equation is general in the sense that it is extendable to the both subgroup methods.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Generalized Approach to Optimize Subgroup Parameters

Yamamoto

2004

Journal of Nuclear Science and Technology

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The comparison of the two subgroup methods, the fitting method and the moment method, was made. It was proved that the both methods are identical under a special condition for the background cross section. More detailed analysis was done from the actual derivation process of the two methods and a generalized formulation was shown that is applicable to the both methods. It became clear that the moment method is regarded as a modified version of the fitting method with a flexible weighting function. It was also concluded that the two methods are identical when the parameter of the moment method takes a specified value (I¼1).Two optimization procedures were proposed to obtain the best subgroup parameters by the use of the least square fitting. One of the methods enables to reduce the error in effective cross section from 6 to 2%.

show abstract

Section: A General Comparison Of Fitting Methods and The Moment Mementioning

confidence: 86%

“…(8) and (9) does not directly appear in the actual derivation of the parameters in the fitting and the moment method. Let us look into the derivation scheme of the two methods.…”

Section: More Detailed Comparisonmentioning

confidence: 99%

See 1 more Smart Citation

A Generalized Approach to Optimize Subgroup Parameters

Yamamoto

2004

Journal of Nuclear Science and Technology

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“…This equation is originally proposed for sub-group parameter generation [11], but s b dependency for the usual multi-group cross-section is larger than that for the sub-group cross-section. In order to improve the interpolation accuracy of s g , the polynomial hyperbolic tangent formulation is derived in the present study as a natural extension of Equation (11):…”

Section: New Derivation Of Polynomial Hyperbolic Tangent Format Librarymentioning

confidence: 99%

Advanced resonance self-shielding method for gray resonance treatment in lattice physics code GALAXY

Koike

Yamaji

Kirimura

et al. 2012

Journal of Nuclear Science and Technology

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A new resonance self-shielding method based on the equivalence theory is developed for general application to the lattice physics calculations. The present scope includes commercial light water reactor (LWR) design applications which require both calculation accuracy and calculation speed. In order to develop the new method, all the calculation processes from cross-section library preparation to effective cross-section generation are reviewed and reframed by adopting the current enhanced methodologies for lattice calculations. The new method is composed of the following four key methods: (1) cross-section library generation method with a polynomial hyperbolic tangent formulation, (2) resonance selfshielding method based on the multi-term rational approximation for general lattice geometry and gray resonance absorbers, (3) spatially dependent gray resonance self-shielding method for generation of intra-pellet power profile and (4) integrated reaction rate preservation method between the multi-group and the ultra-fine-group calculations. From the various verifications and validations, applicability of the present resonance treatment is totally confirmed. As a result, the new resonance self-shielding method is established, not only by extension of a past concentrated effort in the reactor physics research field, but also by unification of newly developed unique and challenging techniques for practical application to the lattice physics calculations.

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“…In the previous paper, the author derived a general formula that define the subgroup parameters including the background-cross-section dependence of the parameters. 8) The direct application of the formula can produce the 'best' definition of the subgroup parameters for a given set of subgroup boundaries, i.e., the lower and upper boundaries of the total cross sections of each subgroup. At the same time, the equation is general in the sense that it is extendable to the both subgroup methods.…”

Section: Introductionmentioning

confidence: 99%

A Generalized Approach to Optimize Subgroup Parameters

Yamamoto

2004

J. Nucl. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

The comparison of the two subgroup methods, the fitting method and the moment method, was made. It was proved that the both methods are identical under a special condition for the background cross section. More detailed analysis was done from the actual derivation process of the two methods and a generalized formulation was shown that is applicable to the both methods. It became clear that the moment method is regarded as a modified version of the fitting method with a flexible weighting function. It was also concluded that the two methods are identical when the parameter of the moment method takes a specified value (I¼1). Two optimization procedures were proposed to obtain the best subgroup parameters by the use of the least square fitting. One of the methods enables to reduce the error in effective cross section from 6 to 2%.

show abstract

Background-Cross-Section-Dependent Subgroup Parameters

Cited by 6 publications

References 8 publications

A Generalized Approach to Optimize Subgroup Parameters

A Generalized Approach to Optimize Subgroup Parameters

Advanced resonance self-shielding method for gray resonance treatment in lattice physics code GALAXY

A Generalized Approach to Optimize Subgroup Parameters

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