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JAEA Reports

Calculation of nuclear core parameters for HTTR; Report of summer holiday practical training 2021

Isogawa, Hiroki*; Naoi, Motomasa*; Yamasaki, Seiji*; Ho, H. Q.; Katayama, Kazunari*; Matsuura, Hideaki*; Fujimoto, Nozomu*; Ishitsuka, Etsuo

JAEA-Technology 2022-015, 18 Pages, 2022/07

JAEA-Technology-2022-015.pdf:1.37MB

As a summer holiday practical training 2021, the impact of 10 years long-term shutdown on critical control rod position of the HTTR and the delayed neutron fraction ( $_{rm eff}$ ) of the VHTRC-1 core were investigated using Monte-Carlo MVP code. As a result, a long-term shutdown of 10 years caused the critical control rods of the HTTR to withdraw about 4.00.8 cm compared to 3.9 cm in the experiment. The change in critical control rods position of the HTTR is due to the change of some fission products such as $^{241}$ Pu, $^{241}$ Am, $^{147}$ Pm, $^{147}$ Sm, $^{155}$ Gd. Regarding the $_{rm eff}$ calculation of the VHTRC-1 core, the $_{rm eff}$ value is underestimate of about 10% in comparison with the experiment value.

Journal Articles

Sensitivity and uncertainty analysis of $beta_{rm eff}$ for MYRRHA using a Monte Carlo technique

Iwamoto, Hiroki; Stankovskiy, A.*; Fiorito, L.*; Van den Eynde, G.*

EPJ Nuclear Sciences & Technologies (Internet), 4, p.42_1 - 42_7, 2018/11

https://doi.org/10.1051/epjn/2018023

This paper presents a nuclear data sensitivity and uncertainty analysis of the effective delayed neutron fraction $beta_{rm eff}$ for critical and subcritical cores of the MYRRHA reactor using the continuous-energy Monte Carlo transport code MCNP. The $beta_{rm eff}$ sensitivities are calculated by the modified -ratio method proposed by Chiba. Comparing the $beta_{rm eff}$ sensitivities obtained with different scaling factors introduced by Chiba shows that a value of is the most suitable for the uncertainty quantification of $beta_{rm eff}$ . Using the calculated $beta_{rm eff}$ sensitivities and the JENDL-4.0u covariance data, the $beta_{rm eff}$ uncertainties for the critical and subcritical cores are determined to be 2.2 0.2% and 2.0 0.2%, respectively, which are dominated by delayed neutron yield of $^{239}$ Pu and $^{238}$ U.

Journal Articles

Kinetic parameter $beta_{rm eff}/ell$ measurement on low enriched uranyl nitrate solution with single unit cores (600, 280T, 800) of STACY

Tonoike, Kotaro; Miyoshi, Yoshinori; Kikuchi, Tsukasa*; Yamamoto, Toshihiro

Journal of Nuclear Science and Technology, 39(11), p.1227 - 1236, 2002/11

https://doi.org/10.3327/jnst.39.1227

Times Cited Count：21 Percentile：77.32(Nuclear Science & Technology)

Kinetic parameter $beta_{rm eff}/ell$ of low enriched uranyl nitrate solution was measured by the pulsed neutron source method in the STACY. This measurement was repeated systematically over several uranium concentrations from 193.7 gU/ to 432.1 gU/. Used core tanks were two cylindrical tanks whose diameters are 600 mm and 800 mm and one slab tank which has 280 mm thickness and 700 mm width. In this report, experimental data such as solution conditions, critical solution level for each solution condition, subcritical solution levels where measurements were conducted, measured decay time constants of prompt neutron and extrapolated $beta_{rm eff}/ell$ values are described as well as basic principle of the pulsed neutron source method. $beta_{rm eff}/ell$ values were evaluated also by computation with the diffusion code CITATION in SRAC and the nuclear data library JENDL 3.2. Both experimental and computational $beta_{rm eff}/ell$ values show good agreement.

Journal Articles

Adjustment of total delayed neutron yields of $^{235}$ U, $^{238}$ U and $^{239}$ Pu by using results of in-pile measurements of effective delayed neutron fraction

Sakurai, Takeshi; Okajima, Shigeaki

Proceedings of International Conference on the New Frontiers of Nuclear Technology; Reactor Physics, Safety and High-Performance Computing (PHYSOR 2002) (CD-ROM), 12 Pages, 2002/10

The cross section adjustment method was applied to total delayed neutron yields of $^{235}$ U, $^{238}$ U and $^{239}$ Pu of the JENDL-3.2 file by using experimental results of effective delayed neutron fraction $beta_{eff}$ at six cores built in two fast critical facilities of the MASURCA and FCA and a thermal critical facility of the TCA to improve these yields. The adjustment was carried out on the yields given at several incident neutron energy points in the file. Furthermore, to validate these adjusted delayed neutron yields, analyses were performed for the $beta_{eff}$ experiments at ZPR fast critical facility. These adjusted yields brought a reduction of uncertainty of calculated $beta_{eff}$ and an improvement in agreement of $beta_{eff}$ between experiment and calculation.

Journal Articles

Adjustment of total delayed neutron yields of $^{235}$ U, $^{238}$ U and $^{239}$ Pu in JENDL-3.2 using benchmark experiments on effective delayed neutron fraction $beta_{eff}$

Sakurai, Takeshi; Okajima, Shigeaki

Journal of Nuclear Science and Technology, 39(1), p.19 - 30, 2002/01

https://doi.org/10.3327/jnst.39.19

Times Cited Count：6 Percentile：39.48(Nuclear Science & Technology)

The cross section adjustment method was applied to total delayed neutron yields of $^{235}$ U, $^{238}$ U and $^{239}$ Pu of the JENDL-3.2 file by using experimental results of effective delayed neutron fraction $beta_{eff}$ at six cores built in two fast critical facilities of the MASURCA and FCA and a thermal critical facility of the TCA to improve these yields. The adjustment was carried out on the yields given at several incident neutron energy points in the file. After the adjustment, the yield of $^{238}$ U was almost uniformly decreased by about 3% below 7 MeV. The yield of $^{239}$ Pu was increased by 2.6% and that of $^{235}$ U was decreased by 0.9% at the thermal energy point, while the change of yield was less than 0.3% at the other energy points for these nuclides. By using these adjusted yields, the uncertainty of calculated $beta_{eff}$ was reduced and the agreement of $beta_{eff}$ between experiment and calculation was improved.

Journal Articles