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JAEA Reports

Verification of the tables for control rods calibration at NSRR

Motome, Yuiko; Agake, Toshiki; Yanagisawa, Hiroshi

JAEA-Technology 2024-015, 30 Pages, 2025/01

JAEA-Technology-2024-015.pdf:1.36MB

The tables for calibration of control rods were verified, which is used positive period method and improved rod drop method of periodic inspection at Nuclear Safety Research Reactor (NSRR). Those tables are "DOUBLING TIME-REACTIVITY" and "DECAY OF NEUTRON FLUX AFTER INSTANTANEOUS REDUCTION OF REACTIVITY". They are prepared around 1975. Since those tables do not clearly express source of values and records of data used in calculations, the authors verified those tables again. For the verification, the tables were reproduced as follows. For the positive period method, the relationship between the period and reactivity was analytically evaluated by using the inhour equation with NSRR's parameters. For the improved rod drop method, the ratios of neutron flux after the rod drop with parameters of negative reactivities was calculated using the EUREKA- 2 code. As a result, the values described in the tables well agree with those by the present evaluation because it is confirmed that standard deviations of the differences in the value by between the present evaluation and the tables are less than 0.035%. For this reason, it is verified that these tables are valid in the practical use for NSRR operations.

Journal Articles

Transient response of LWR fuels (RIA)

Udagawa, Yutaka; Fuketa, Toyoshi*

Comprehensive Nuclear Materials, 2nd Edition, Vol.2, p.322 - 338, 2020/08

https://doi.org/10.1016/B978-0-12-803581-8.11682-0

Journal Articles

Heat transfer characteristics of the steam reformer in the HTTR hydrogen production system

Takeda, Tetsuaki

Proceedings of 12th International Conference on Nuclear Engineering (ICONE-12) (CD-ROM), 4 Pages, 2004/00

no abstracts in English

JAEA Reports

Determination of reactivity and source intensity based on the maximum likelihood method

Nishihara, Kenji; Iwanaga, Kohei; Yamane, Tsuyoshi; Okajima, Shigeaki

JAERI-Research 2002-030, 63 Pages, 2002/12

JAERI-Research-2002-030.pdf:3.81MB

During the experiments using the critical assembly such that reactivity is added to the stationary state and the core shifts to the other stationary state, the neutron flux transitionally changes after some change of the reactivity or source. Inverse kinetics method (IK method) can generally adopted as the technique of obtaining the reactivity and/or source by analyzing the neutron flux. However, the conventional analysis method was not able to obtain the solution with the maximum likelihood considering the error of the measured neutron flux and to estimate the error of the solution. In the present research, by adopting the maximum likelihood methodology to the problem, developed is the technique to obtain the reactivity and source intensity with maximum likelihood and the errors of them. Moreover, the technique is applied to the rod drops experiment in FCA, and the validity of a technique is checked.

Journal Articles