Science from the initial operation of HRC

Ito, Shinichi*; Yokoo, Tetsuya*; Masuda, Takatsugu*; Yoshizawa, Hideki*; Soda, Minoru*; Ikeda, Yoichi*; Ibuka, Soshi*; Kawana, Daichi*; Sato, Taku*; Nambu, Yusuke*; et al.

JPS Conference Proceedings (Internet), 8, p.034001_1 - 034001_6, 2015/09

https://doi.org/10.7566/JPSCP.8.034001

New integral experiments for large angle scattering cross section data benchmarking with DT neutron beam at JAEA/FNS

Onishi, Seiki*; Kondo, Keitaro*; Azuma, Tetsushi*; Sato, Satoshi; Ochiai, Kentaro; Takakura, Kosuke; Murata, Isao*; Konno, Chikara

Fusion Engineering and Design, 87(5-6), p.695 - 699, 2012/08

https://doi.org/10.1016/j.fusengdes.2012.02.002

A new integral experiment with a deuteron-triton fusion (DT) neutron beam started in order to validate scattering cross section data. First the DT neutron beam was constructed with a collimator. The characteristics of the DT neutron beam were examined experimentally. Second a new integral experiment for type 316 stainless steel (SS316) was carried out with this DT neutron beam. Reaction rates of the Nb(n,2n)Nb reaction on the center of the beam axis and at 15 cm and 30 cm apart from the axis in the assembly were measured with the activation foil method and were calculated with the Monte Carlo transport calculation code MCNP and nuclear data libraries, JENDL-4.0, JENDL-3.3 and ENDF/B-VI.8. The ratios of calculation to experiment became smaller than 1 with the distance from the beam axis for all the nuclear libraries. It was pointed out that the diagonally forward cross section data had some problems.

Detailed benchmark test of JENDL-4.0 iron data for fusion applications

Konno, Chikara; Wada, Masayuki*; Kondo, Keitaro; Onishi, Seiki; Takakura, Kosuke; Ochiai, Kentaro; Sato, Satoshi

Fusion Engineering and Design, 86(9-11), p.2682 - 2685, 2011/10

https://doi.org/10.1016/j.fusengdes.2011.01.097

JENDL-4, the major revised version of Japanese Evaluated Nuclear Data Library (JENDL), was released in spring, 2010. We analyzed the fusion neutronics benchmark experiments on iron at JAEA/FNS with JENDL-4.0 and MCNP4C as the detail benchmark test of JENDL-4.0 iron data. As a result, it is found out that the problems of iron data in JENDL-3.3 are adequately revised in JENDL-4.0 iron data; e.g. the first inelastic scattering cross section data of Fe and angular distribution of elastic scattering of Fe. The iron data in JENDL-4.0 are comparable to and are partly better than those in ENDF/B-VII.0 and JEFF-3.1.

Benchmark test of JENDL-4.0 based on integral experiments at JAEA/FNS

Konno, Chikara; Takakura, Kosuke; Wada, Masayuki*; Kondo, Keitaro; Onishi, Seiki*; Ochiai, Kentaro; Sato, Satoshi

Progress in Nuclear Science and Technology (Internet), 2, p.346 - 357, 2011/10

https://doi.org/10.15669/pnst.2.346

The major revised version of Japanese Evaluated Nuclear Data Library (JENDL), JENDL-4, was released in 2010 spring. As the benchmark test of JENDL-4.0 in the shielding and fusion neutronics fields, we analyzed many integral benchmark experiments (in-situ and Time-of-Flight (TOF) experiments) with DT neutrons at JAEA/FNS with the MCNP code and JENDL-4.0. The experiments with assemblies including beryllium, carbon, silicon, vanadium, copper, tungsten and lead, nuclear data of which were revised in JENDL-4.0, were selected for this benchmark test. As a result, it is found that JENDL-4 improved some problems pointed out in JENDL-3.3 and that it is comparable to ENDF/B-VII.0 and JEFF-3.1.

Implementation of a collimated DT neutron beam at the 1st target room of JAEA/FNS for new integral benchmark experiments

Onishi, Seiki; Kondo, Keitaro; Sato, Satoshi; Ochiai, Kentaro; Takakura, Kosuke; Konno, Chikara; Murata, Isao*

Journal of the Korean Physical Society, 59(2), p.1949 - 1952, 2011/08

https://doi.org/10.3938/jkps.59.1949

So far we carried out many integral benchmark experiments (in-situ experiments and Time-Of-Flight experiments) for nuclear data with DT neutrons at the Fusion Neutronics Source facility in Japan Atomic Energy Agency. In addition to those, we have a plan to perform new integral benchmark experiments for nuclear data with a DT neutron beam, which can investigate nuclear data for almost the whole angle and the whole energy. Because the large-size tritium target in FNS is difficult to procure, we have started to build a new DT neutron beam with the small tritium target, which is easy to obtain, at the first target room of FNS. We already designed a collimator system for the DT neutron beam based on calculations. In this work, under that design, the collimator was constructed. Then the characteristics of the neutron field were measured in order to confirm the DT neutron beam performance. It was demonstrated that the DT neutron beam was realized as calculated.

Integral experiment on beryllium with DD neutrons for nuclear data benchmarking

Kondo, Keitaro; Ochiai, Kentaro; Tatebe, Yosuke; Yagi, Takahiro; Onishi, Seiki; Takakura, Kosuke; Sato, Satoshi; Konno, Chikara

Progress in Nuclear Science and Technology (Internet), 1, p.61 - 64, 2011/02

https://doi.org/10.15669/pnst.1.61

At the Fusion Neutronics Source (FNS) facility of JAEA we have conducted various integral experiments with DT neutrons for fusion reactor materials and have made a significant progress in the verification of their nuclear data. Recently we started a new series of integral experiments with DD neutrons at FNS in order to verify nuclear data relating to DD neutrons effectively. An integral experiment on beryllium with the DD neutron source will be presented in this conference. A beryllium pseudo-cylinder assembly of 45 cm in thickness and 63 cm in the diameter was built at the distance of 20 cm from the DD neutron source, and reaction rates of the In(n,n')In, Au(n,)Au and Li(n,)T reactions and a U fission rate were measured. The measured values were compared with calculations with the MCNP5 code and the latest nuclear data libraries; JENDL-3.3, ENDF/B-VII.0 and JEFF-3.1. A slight disagreement between the measurement and the calculation was found in the reaction rate of In, which is sensitive to neutrons above 0.3 MeV. We identified that the disagreement originated from the angular differential cross section data of the elastic scattering around 3 MeV and from the (n,2n) reaction cross section data near its threshold energy. The calculated reaction rates of Au, Li and U, which are sensitive to low energy neutrons, showed a large overestimation, which also appeared at the beryllium integral experiment with DT neutrons previously carried out at FNS. This problem has not been solved yet.

Collimator system design for a DT neutron beam at the first target room of JAEA/FNS

Onishi, Seiki; Sato, Satoshi; Ochiai, Kentaro; Takakura, Kosuke; Kondo, Keitaro; Konno, Chikara

Progress in Nuclear Science and Technology (Internet), 1, p.73 - 76, 2011/02

https://doi.org/10.15669/pnst.1.73

There are two target rooms at the Fusion Neutronics Source (FNS) facility in Japan Atomic Energy Agency (JAEA). Recently it becomes increasingly difficult to meet needs for experiments with a DT neutron beam such as instrument development for ITER, because of shortage of the large target. Therefore we plan to construct a neutron beam inside TR1 by using the small tritium target of TR1, which is easier to obtain. We designed the collimator system based on the cylindrical assembly used in the previous ITER shielding experiments at JAEA/FNS. Neutron spectra at the exit of the collimator and at the offset position by 20 cm from the collimator axis were calculated with the two dimensional Sn code DORT and FENDL/MG-2.1 multi-group library in order to investigate the effect of the collimator system.

Detail analysis of fusion neutronics benchmark experiment on beryllium

Konno, Chikara; Ochiai, Kentaro; Takakura, Kosuke; Onishi, Seiki; Kondo, Keitaro; Wada, Masayuki*; Sato, Satoshi

Fusion Engineering and Design, 85(10-12), p.2054 - 2058, 2010/12

https://doi.org/10.1016/j.fusengdes.2010.07.026

In the last ISFNT, we presented re-analyses of fusion neutronics benchmark experiments on beryllium at JAEA/FNS and reported that all the calculations with JENDL-3.3, FENDL-2.1, JEFF-3.1 and ENDF/B-VII.0 overestimated experimental data on low energy neutrons and that the calculation with JEFF-3.1 had a strange peak around 12 MeV. Here we investigate reasons for these problems. As a result, It was found out that the official ACE file MCJEFF3.1 of JEFF-3.1 had an inconsistency with the original JEFF-3.1, which caused the strange larger neutron peak around 12 MeV. We also find out that the calculated thermal neutron peak is probably too large. It is indicated that the coherent elastic scattering cross section data in the thermal neutron flux law data of beryllium metal are too large.

Measurement of DT and DD neutrons with a TOF spectrometer for determination of fuel ion density ratio in ITER

Okada, Koichi*; Kondo, Keitaro; Ochiai, Kentaro; Sato, Satoshi; Konno, Chikara; Okamoto, Atsushi*; Kobuchi, Takashi*; Kitajima, Sumio*; Sasao, Mamiko*

Journal of Plasma and Fusion Research SERIES, Vol.8, p.666 - 669, 2009/09

Measurement of fuel ion density ratio, /, is required for burning control on ITER. The measured / ratio must be fed back in real time. A neutron measurement system to measure / should be operable at high counting rate. It is estimated that the number of emitted DT neutrons is 200 times higher than that of DD neutrons under the condition of ITER standard operation. A neutron measurement system was developed using a DT/DD generator, where DT neutrons are dominant and DD neutrons are contaminated slightly in the neutron beam. The measurement instrument was a TOF spectrometer. Signals originating from each neutron must be distinguished in order to measure the fuel ratio. We developed a circuit system with discrimination windows to distinguish each signal pulse, and DT and DD neutrons were measured separately and simultaneously with this system. The experimental result indicates a possibility that this system is suitable for measurement of fuel ion density ratio on ITER.

Thin slit streaming experiment for ITER by using D-T neutron source

Ochiai, Kentaro; Sato, Satoshi; Wada, Masayuki*; Kubota, Naoyoshi; Kondo, Keitaro; Yamauchi, Michinori; Abe, Yuichi; Nishitani, Takeo; Konno, Chikara

Fusion Engineering and Design, 82(15-24), p.2794 - 2798, 2007/10

https://doi.org/10.1016/j.fusengdes.2007.05.076

Neutron streaming experiments have been conducted by using the FNS D-T neutron source at Japan Atomic Energy Agency under the ITER/ITA Task 73-10 in order to evaluate effects of the slit on nuclear properties and validate prediction accuracies on numerical simulations. The experimental assembly with a slit of 2 cm in width and 55 cm in depth was prepared with two iron blocks of 30 cm in height, 100 cm in width and 55cm in thickness as first campaign. The slit was located in the 12-cm upper part from the D-T neutron source point. In order to evaluate distributions of the neutron fluxes along the slit as a function of the depth from the assembly surface, fission reaction rates were measured by U-238 and U-235 micro-fission chambers. The experimental accuracies of these fission reaction rates are within 5%. Monte-Carlo calculation code, MCNP-4c, was used to calculate the U-238 and U-235 reaction rates and neutron energy spectra due to each measured position. From our first experiment, the following facts were found: (1) At d = 20 and 40 cm, reaction rates on U-238, which represent fast neutron flux, decreased by about three orders of magnitude along slits with 50 cm in depth. Monte Carlo calculation results agree well with measured values within 6 %. (2) Reaction rates on U-235, which represent thermal neutron flux, decrease by about one order of magnitude along slits with 50 cm in depth. Values of C/E of U-238 and U-235 reaction rates were 1.10-1.22 and 1.10-1.23 respectively and the calculated values overestimated slightly.