JOPSS - Search Results

Search Results: Records 1-20 displayed on this page of 20

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Journal Articles

Reactivity estimation based on the linear equation of characteristic time profile of power in subcritical quasi-steady state

Yamane, Yuichi

Journal of Nuclear Science and Technology, 59(11), p.1331 - 1344, 2022/11

https://doi.org/10.1080/00223131.2022.2053221

Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)

The reactivity was estimated from a time profile of neutron count rate or a simulated data in a quasi-steady state after sudden change of reactivity or external neutron source strength. The estimation was based on the equation of power in subcritical quasi-steady state. The purpose of the study is to develop the method of timely reactivity estimation from complicated time profile of neutron count rate. The developed method was applied to the data simulating neutron count rate created by using one-point kinetics code, AGNES, and Poisson-distributed random noise and to the transient subcritical experiment data measured by using TRACY. The result shows that the difference of the estimated and reference value was within about 5% or less for ( -1) for simulated data and within about 7% or less for -1.4 and -3.1 for the experimental data. It was also shown that the possibility of the reactivity estimation several ten seconds after the status change.

Journal Articles

Subcriticality determination methodology during fuel loading of accelerator-driven system

Katano, Ryota

Journal of Nuclear Science and Technology, 59(3), p.368 - 381, 2022/03

https://doi.org/10.1080/00223131.2021.1973609

Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)

We propose a subcriticality determination methodology to be applied during fuel loading of an accelerator-driven system (ADS). In this methodology, subcriticality is determined via the area ratio method (via the proton accelerator) in the first step and by the neutron source multiplication method (through the spontaneous fission neutrons of minor actinides) in subsequent steps; then, the number of fuel assemblies to be loaded in the next step is predicted. We performed a numerical simulation of the proposed methodology, and the estimated subcriticalities agreed well with those obtained by eigenvalue calculations. We also conducted an uncertainty assessment of the proposed methodology and deduced a value of 1000 pcm for the $k_{eff}$ uncertainty. The proposed methodology can be a candidate for practical subcriticality monitoring for ADS.

Journal Articles

A Linear Equation of characteristic time profile of power in subcritical quasi-steady state

Yamane, Yuichi

Journal of Nuclear Science and Technology, 57(8), p.926 - 931, 2020/08

https://doi.org/10.1080/00223131.2020.1736682

Times Cited Count：1 Percentile：12.16(Nuclear Science & Technology)

An equation of power in subcritical quasi-steady state has been derived based on one-point kinetics equations for the purpose of utilizing it for the development of timely reactivity estimation from complicated time profile of neutron count rate. It linearly relates power, , to a new variable , which is a function of time differential of the power. It has been confirmed by using one-point kinetics code, AGNES, that the calculated points () are perfectly in a line described by the new equation and that points () calculated from transient subcritical experiments by using TRACY made a line with a slope indicated by the new equation.

Journal Articles

Application of linear combination method to pulsed neutron source measurement at Kyoto University Critical Assembly

Katano, Ryota; Yamanaka, Masao*; Pyeon, C. H.*

Nuclear Science and Engineering, 193(12), p.1394 - 1402, 2019/12

https://doi.org/10.1080/00295639.2019.1624084

Times Cited Count：5 Percentile：48.99(Nuclear Science & Technology)

The author proposed the linear combination method as a subcriticality measurement method which estimates the prompt neutron decay constant (alpha) correlated with the subcriticality using measurement results obtained at multiple detector positions. In this study, we conduct the pulsed neutron experiment at Kyoto University Critical Assembly (KUCA) and measure alpha by the linear combination method using measured neutron counts. Through experiment, we experimentally show that the linear combination method can reduce the higher-mode effect compared to the conventional method. In addition, experimentally show that the linear combination has capability of the different mode extraction.

Journal Articles

Area ratio method via linear combination of the neutron counts in pulsed neutron experiment

Katano, Ryota

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 6 Pages, 2019/05

no abstracts in English

Journal Articles

Estimation method of prompt neutron decay constant reducing higher order mode effect by linear combination

Katano, Ryota

Nuclear Science and Engineering, 193(4), p.431 - 439, 2019/04

https://doi.org/10.1080/00295639.2018.1528803

Times Cited Count：6 Percentile：55.67(Nuclear Science & Technology)

We proposed "linear combination method" to reduce the higher order mode effect on the prompt neutron decay constant measured by the pulsed neutron experiment. When the spatial higher order mode effect is taken into account, the time evolution of the neutron counts after the pulsed neutron injection is given by linear combination of multiple exponential functions. However, the measurement results by the conventional method include the systematic error derived from the higher order mode effect because the conventional method fit the neutron counts with a single exponential function. The proposed method extract the single exponential function of the fundamental mode by linear combination of the neutron counts at multiple detectors, thus the proposed method reduces the higher order mode effect. As the verification, we applied the proposed method to the numerical simulation. The results indicate that the proposed method can reduce the higher order mode effect by linear combination.

Journal Articles

On-line subcriticality measurement using a pulsed spallation neutron source

Iwamoto, Hiroki; Nishihara, Kenji; Yagi, Takahiro*; Pyeon, C.-H.*

Journal of Nuclear Science and Technology, 54(4), p.432 - 443, 2017/04

https://doi.org/10.1080/00223131.2016.1274687

Times Cited Count：20 Percentile：88.58(Nuclear Science & Technology)

Journal Articles

Calculation of nuclear characteristic parameters and drawing subcriticality judgment graphs of infinite fuel systems for typical nuclear fuels

Okuno, Hiroshi; Takada, Tomoyuki

Journal of Nuclear Science and Technology, 41(4), p.481 - 492, 2004/04

https://doi.org/10.3327/jnst.41.481

Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)

Nuclear characteristic parameters were calculated and subcriticality judgement graphs were drawn for revision purposes of the Data Collection for the Nuclear Criticality Safety Handbook. The nuclear characteristic parameters were the neutron multiplication factor in infinite media, migration area and diffusion constants for 11 kinds of typical fuels encountered in criticality safety evaluation of nuclear fuel cycle facilities. These fuels included ADU-H $_{2}$ O, UF6-HF and Pu(NO $_{3}$ ) $_{4}$ -UO $_{2}$ (NO $_{3}$ ) $_{2}$ solution, of which data were not cited in the Data Collection. The calculation was made with the Japanese evaluated nuclear data library JENDL-3.2 and a sequence of criticality calculation codes, SRAC, POST and SIMCRI. The subcriticality judgement graphs that depict the region satisfying the inequality relation of the neutron multiplication factor less than 0.98 between the two variables (a) uranium enrichment, 239Pu/Pu ratio or plutonium enrichment and (b) H/(Pu+U) ratio were drawn for the same kinds of fuels except UF6-HF in infinite media.

Journal Articles

Revised data for 2nd version of Nuclear Criticality Safety Handbook/Data Collection

Okuno, Hiroshi; Ryufuku, Susumu*; Suyama, Kenya; Nomura, Yasushi; Tonoike, Kotaro; Miyoshi, Yoshinori

JAERI-Conf 2003-019, p.116 - 121, 2003/10

https://doi.org/10.11484/jaeri-conf-2003-019

This paper outlines the data prepared for the 2nd version of Data Collection of the Nuclear Criticality Safety Handbook. These data are discussed in the order of its preliminary table of contents. The nuclear characteristic parameters (k $_{rm inf}$ , M $^{2}$ , D) were derived, and subcriticality judgment graphs were drawn for eleven kinds of fuels which were often encountered in criticality safety evaluation of fuel cycle facilities. For calculation of criticality data, benchmark calculations using the combination of the continuous energy Monte Carlo criticality code MVP and the Japanese Evaluated Nuclear Data Library JENDL-3.2 were made. The calculation errors were evaluated for this combination. The implementation of the experimental results obtained by using NUCEF facilities into the 2nd version of the Data Collection is under discussion. Therefore, related data were just mentioned. A database is being prepared to retrieve revised data easily.

Journal Articles

A New static and dynamic one-point equation and analytic and numerical calculations for a subcritical system

Nishihara, Kenji; Iwasaki, Tomohiko*; Udagawa, Yutaka*

Journal of Nuclear Science and Technology, 40(7), p.481 - 492, 2003/07

https://doi.org/10.3327/jnst.40.481

Times Cited Count：17 Percentile：72.74(Nuclear Science & Technology)

A new one-point equation is derived according to the balance of the fission neutrons. The equation has the same form as the conventional equation containing keff. The variables of the equation are the number of the fission neutrons and the delayed neutron precursors, and the coefficients are the multiplication factors of a prompt fission neutron, a delayed neutron and a source neutron. In the equation derived here, all variables and coefficients have each clear physical meaning. Analytic, deterministic and probabilistic calculations of the equation are performed for an accelerator-driven system.

JAEA Reports

Measurement and analysis of neutron flux distribution of STACY heterogeneous core by position sensitive proportional counter (Contract research)

Murazaki, Minoru; Uno, Yuichi; Miyoshi, Yoshinori

JAERI-Tech 2003-029, 107 Pages, 2003/03

JAERI-Tech-2003-029.pdf:7.04MB

We have measured neutron flux distribution around the core tank of STACY heterogeneous core by position sensitive proportional counter (PSPC) to develop the method to measure reactivity for subcritical systems. The neutron flux distribution data in the position accuracy of 13mm have been obtained in the range of uranium concentration of 50g/L to 210g/L both in critical and in subcritical state. The prompt neutron decay constant, , was evaluated from the measurement data of pulsed neutron source experiments. We also calculated distribution of neutron flux and $^{3}$ He reaction rates at the location of PSPC by using continuous energy Monte Carlo code MCNP. The measurement data was compared with the calculation results. As results of comparison, calculated values agreed generally with measurement data of PSPC with Cd cover in the region above half of solution height, but the difference between calculated value and measurement data was large in the region below half of solution height. On the other hand, calculated value agreed well with measurement data of PSPC without Cd cover.