Generalized formulation of extended cross-section adjustment method based on minimum variance unbiased linear estimation

Yokoyama, Kenji; Kitada, Takanori*

Journal of Nuclear Science and Technology, 56(1), p.87 - 104, 2019/01

https://doi.org/10.1080/00223131.2018.1531078

no abstracts in English

Cross-section adjustment methods based on minimum variance unbiased estimation

Yokoyama, Kenji; Yamamoto, Akio*

Journal of Nuclear Science and Technology, 53(10), p.1622 - 1638, 2016/10

AA2015-0624.pdf:0.29MB

https://doi.org/10.1080/00223131.2016.1146637

On the basis of the minimum variance approach, the unified formulation for three types of the cross-section adjustment methods has been derived in a straightforward way without assuming the normal distribution. These methods are intended to minimize the variances of the predicted target core parameters, the adjusted cross-section set, and the calculated integral experimental values. The first and the second methods are found to be slightly different from the extended and the conventional cross-section adjustment methods based on the Bayesian approach with the normal distribution assumption, respectively. However, they become equivalent in some cases and results. The third method is a new method, which is necessary from the viewpoint of the symmetry of the formulation. The derivation procedure proposed in the present paper is potentially applicable to developing more sophisticated cross-section adjustment methods because of the less assumptions on the probability density function.

Preparation of computer codes for analyzing sensitivity coefficients of burnup characteristics

*; *; Sanda, Toshio*

PNC TJ9124 93-009, 334 Pages, 1993/03

PNC-TJ9124-93-009.pdf:7.49MB

To commertialize LMFBR, they are important subjects of research and development to improve the accuracy in neutronic design of large LMFBR cores and to make be able to design highly efficient core more rationaoy. The adjusted library has been made by being reflected the result of critical experiment of the JUPITER, etc. effectively as much as possible by using the cross-sections adjustment method based on the probabilistic theory. And the distinct improvement of the accuracy in neutronic design of large LMFBR cores has been achieved. In the design of large LMFBR cores, however, it is important to accurately estimate not only neutronic characteristics, for example, reaction rate distribution and control rod worth but also burnup characteristics, for example, burnup reactivity loss, breeding ratio and so on. Therefore the objective of the work is to improve the prediction accuracy for burnup characteristics using many burnup data of "Joyo" effectively. For the objective computer codes for analyzing sensitivity coefficients of burnup characteristics were prepared and cross-sections adjustment using burnup data of "Joyo" was done and the effect for the improvement of the accuracy for burnup characteristics was estimated. The results are as follows: (1)The computer codes which could analyze sensitivity coefficients of burnup characteristics of LMFBR taking into consideration plural cycles and refueling were prepared and their adequacy was made sure by comparing with direct calculations. (2)It was clarified that it is possible to improve the accuracy of burnup characteristics without affecting statically neutronic characteristics so much by applying the burnup characteristics to cross-sections adjustment.

Cross section adjustment methods based on minimum variance unbiased estimate

Yokoyama, Kenji; Yamamoto, Akio*

no journal, , 

no abstracts in English

Dimension-reduced cross-section adjustment method

Yokoyama, Kenji; Yamamoto, Akio*; Kitada, Takanori*

no journal, , 

no abstracts in English

Summary of derivations and equivalence between bias factor methods and adjustment methods

Yokoyama, Kenji

no journal, , 

no abstracts in English