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Journal Articles

Soil microbial community responding to moderately elevated nitrogen deposition in a Japanese cool temperate forest surrounded by fertilized grasslands

Nagano, Hirohiko; Nakayama, Masataka*; Katata, Genki*; Fukushima, Keitaro*; Yamaguchi, Takashi*; Watanabe, Makoto*; Kondo, Toshiaki*; Atarashi-Andoh, Mariko; Kubota, Tomohiro*; Tateno, Ryunosuke*; et al.

Soil Science and Plant Nutrition, 67(5), p.606 - 616, 2021/10

 Times Cited Count:2 Percentile:23.6(Plant Sciences)

We analyzed the relationships between nitrogen deposition (deposition of nitrate and ammonium ions) and soil microbial properties in a cool temperate forest surrounded by normally fertilized pasture grasslands in northern Japan. The aim of the present study was to gain the primary information on soil microbial response to moderately elevated nitrogen deposition ($$<$$ 10 kg N ha$$^{-1}$$ y$$^{-1}$$). We established three experimental plots in the forest edge adjacent to grasslands and other three plots in the forest interior at least 700 m away from the grasslands. During May to November 2018, nitrogen deposition in each plot was measured. In August 2018, litter and soil (0-5 cm depth) samples were collected from all plots to measure net nitrogen mineralization and nitrification rates as indicators of microbial activity, and microbial biomass carbon and nitrogen and various gene abundances (i.e. bacterial 16S rRNA, fungal ITS, bacterial amoA, and archaeal amoA genes) as indicators of microbial abundance and structure. Nitrogen deposition in the forest edge was 1.4-fold greater than that in the forest interior, even while the maximum deposition was 3.7 kg N ha$$^{-1}$$. Nitrogen deposition was significantly correlated to the net nitrogen mineralization and nitrification rates and the 16S rRNA and bacterial amoA gene abundances. Microbial community structures were different between litter and soil samples but were similar between the forest edge and interior. Significant correlations of nitrogen deposition to the soil carbon to nitrogen ratio, and the nitrate and ammonium contents were also observed. Thus, our results show that moderately elevated nitrogen deposition in nitrogen-limited forest edges can stimulate microbial activities and abundances in soils.

Journal Articles

Recent progress in the fusion neutrons, 3; Nuclear analysis by automatic conversion of CAD data

Sato, Satoshi; Kondo, Keitaro

Purazuma, Kaku Yugo Gakkai-Shi, 92(4), p.266 - 268, 2016/04

In the nuclear analysis of ITER, fusion DEMO reactor and IFMIF, etc., radiation transport calculations are conducted by using MCNP geometry data automatically created from 3-dimensional CAD data with CAD/MCNP conversion codes. In this review paper, we introduce the present status of the development on the CAD/MCNP conversion codes and examples of application. Also, we introduce how to visualize calculation results by MCNP.

Journal Articles

Measurement of ion species in high current ECR H$$^+$$/D$$^+$$ ion source for IFMIF (International Fusion Materials Irradiation Facility)

Shinto, Katsuhiro; Sen$'e$e, F.*; Ayala, J.-M.*; Bolzon, B.*; Chauvin, N.*; Gobin, R.*; Ichimiya, Ryo; Ihara, Akira; Ikeda, Yukiharu; Kasugai, Atsushi; et al.

Review of Scientific Instruments, 87(2), p.02A727_1 - 02A727_3, 2016/02

 Times Cited Count:8 Percentile:40.22(Instruments & Instrumentation)

Journal Articles

Present status of the injector for IFMIF Linear Prototype Accelerator (LIPAc)

Shinto, Katsuhiro; Ichikawa, Masahiro; Takahashi, Hiroki; Kondo, Keitaro; Kasugai, Atsushi; Gobin, R.*; Sen$'e$e, F.*; Chauvin, N.*; Ayala, J.-M.*; Marqueta, A.*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.493 - 495, 2015/09

Development of the prototype accelerator (LIPAc) for the engineering validation of the International Fusion Materials Irradiation Facility (IFMIF) which is an accelerator driven neutron source has been progressed at Rokkasho. The LIPAc is a deuteron linear accelerator consisting of an injector, a radio-frequency quadrupole (RFQ) linac and a superconducting linac. The objective of LIPAc is to produce a CW beam with the energy and current of 9 MeV and 125 mA, respectively. The injector was developed at CEA/Saclay and succeeded to produce CW proton and deuteron beams of 100 keV/140 mA by autumn 2012. After the test at CEA/Saclay, the injector was shipped to the International Fusion Energy Research Centre (IFERC) in Rokkasho, Aomori and started to reassemble from the end of 2013. It was successfully produced proton beams in November 2014 at Rokkasho. While the ion source conditioning was done, the beam test was progressed. In this paper, the present status of the LIPAc injector at Rokkasho with some experimental results will be presented.

Journal Articles

Progress of the high current Prototype Accelerator for IFMIF/EVEDA

Okumura, Yoshikazu; Ayala, J.-M.*; Bolzon, B.*; Cara, P.*; Chauvin, N.*; Chel, S.*; Gex, D.*; Gobin, R.*; Harrault, F.*; Heidinger, R.*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.203 - 205, 2015/09

Under the framework of Broader Approach (BA) agreement between Japan and Euratom, IFMIF/EVEDA project was launched in 2007 to validate the key technologies to realize IFMIF. The most crucial technology to realize IFMIF is two set of linear accelerator each producing 125mA/CW deuterium ion beams up to 40MeV. The prototype accelerator, whose target is 125mA/CW deuterium ion beam acceleration up to 9MeV, is being developed in International Fusion Research Energy Center (IFERC) in Rokkasho, Japan. The injector developed in CEA Saclay was delivered in Rokkasho in 2014, and is under commissioning. Up to now, 100keV/120mA/CW hydrogen ion beams and 100keV/90mA/CW duty deuterium ion beams are successfully produced with a low beam emittance of 0.21 $$pi$$.mm.mrad (rms, normalized). Delivery of RFQ components will start in 2015, followed by the installation of RF power supplies in 2015.

Journal Articles

The Accomplishment of the engineering design activities of IFMIF/EVEDA; The European-Japanese project towards a Li(d,xn) fusion relevant neutron source

Knaster, J.*; Ibarra, A.*; Ida, Mizuho*; Kondo, Keitaro; Kikuchi, Takayuki; Ohira, Shigeru; Sugimoto, Masayoshi; Wakai, Eiichi; Watanabe, Kazuhito; 58 of others*

Nuclear Fusion, 55(8), p.086003_1 - 086003_30, 2015/08

 Times Cited Count:58 Percentile:95.66(Physics, Fluids & Plasmas)

The International Fusion Materials Irradiation Facility (IFMIF), presently in its Engineering Validation and Engineering Design Activities (EVEDA) phase under the frame of the Broader Approach Agreement between Europe and Japan, has accomplished in summer 2013, on schedule, its EDA phase with the release of the engineering design report of the IFMIF plant, which is here described. Many improvements of the design from former phases are implemented, particularly a reduction of beam losses and operational costs thanks to the superconducting accelerator concept. In the Test Cell design, the separation of the irradiation modules from the shielding block gaining irradiation flexibility and enhancement of the remote handling equipment reliability and cost reduction. The released IFMIF Intermediate Engineering Design Report, which could be complemented if required concurrently with the outcome of the on-going EVA carried out since the entry into force of IFMIF/EVEDA in June 2007, will allow the decision making on its construction and/or serve as the basis for the definition of the next step, aligned with the evolving needs of our fusion community.

Journal Articles

Development of small specimen test techniques for the IFMIF test cell

Wakai, Eiichi; Kim, B. J.; Nozawa, Takashi; Kikuchi, Takayuki; Hirano, Michiko*; Kimura, Akihiko*; Kasada, Ryuta*; Yokomine, Takehiko*; Yoshida, Takahide*; Nogami, Shuhei*; et al.

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 6 Pages, 2013/03

Journal Articles

Effect of sweep gas species on tritium release behavior from lithium titanate packed bed during 14MeV neutron irradiation

Kawamura, Yoshinori; Ochiai, Kentaro; Hoshino, Tsuyoshi; Kondo, Keitaro*; Iwai, Yasunori; Kobayashi, Kazuhiro; Nakamichi, Masaru; Konno, Chikara; Yamanishi, Toshihiko; Hayashi, Takumi; et al.

Fusion Engineering and Design, 87(7-8), p.1253 - 1257, 2012/08

 Times Cited Count:15 Percentile:74.15(Nuclear Science & Technology)

Tritium generation and recovery study on lithium ceramic packed bed was started by use of FNS in JAEA. Lithium titanate was selected as tritium breeding material. In this work, the effect of sweep gas species on tritium release behavior was investigated. In case of sweep by helium with 1% of hydrogen, tritium in water form was released sensitively corresponding to the irradiation. This is due to existence of the water vapor in the sweep gas. On the other hand, in case of sweep by dry helium, tritium in gaseous form was released first, and release of tritium in water form was delayed and was gradually increased.

Journal Articles

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

 Times Cited Count:9 Percentile:64.26(Nuclear Science & Technology)

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 $$^{93}$$Nb(n,2n)$$^{rm 92m}$$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.

Journal Articles

Investigation on the TPR prediction accuracy in blanket neutronics experiments with reflector at JAEA/FNS

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

Fusion Engineering and Design, 86(9-11), p.2184 - 2187, 2011/10

 Times Cited Count:2 Percentile:18.56(Nuclear Science & Technology)

In the neutronics experiment for the ITER test blanket module with a $$^{6}$$Li-enriched Li$$_{2}$$TiO$$_{3}$$ layer and a beryllium layer conducted at the FNS facility of Japan Atomic Energy Agency, the calculated tritium production rate (TPR) was by approximately 10% larger than the measured one only when a neutron source reflector composed of SS316 was attached. On the other hand, the influence of the reflector on the TPR prediction accuracy was not seen in the recent blanket experiment with a natural Li$$_{2}$$TiO$$_{3}$$ layer, beryllium layers and the reflector. We investigated the former experiment in detail, and found an unphysical tendency in the measured TPR distribution. In order to clarify whether the deterioration of the TPR prediction accuracy originates from the reflector or not, we have conducted the same experiment as the previous experiment again. In the present experiment, the measured TPR distribution inside the $$^{6}$$Li-enriched Li$$_{2}$$TiO$$_{3}$$ layer well agreed with the calculated one within an estimated experimental error of 6%. We conclude that the overestimation of TPR observed in the previous experiment would be due to some experimental errors and that the TPR prediction accuracy is good even in the case with the reflector.

Journal Articles

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

 Times Cited Count:4 Percentile:33.04(Nuclear Science & Technology)

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 $$^{57}$$Fe and angular distribution of elastic scattering of $$^{56}$$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.

Journal Articles

Performance analysis of fusion nuclear-data benchmark experiments for light to heavy materials in MeV energy region with a neutron spectrum shifter

Murata, Isao*; Ota, Masayuki*; Miyamaru, Hiroyuki*; Kondo, Keitaro; Yoshida, Shigeo*; Iida, Toshiyuki*; Ochiai, Kentaro; Konno, Chikara

Journal of Nuclear Materials, 417(1-3), p.1127 - 1130, 2011/10

 Times Cited Count:2 Percentile:18.56(Materials Science, Multidisciplinary)

Nuclear data are indispensable for development of fusion reactor candidate materials. However, benchmarking of the nuclear data in MeV energy region is not sufficient even now. In the present study, benchmark performance in the MeV energy region was investigated theoretically in case of experiments by using a 14MeV neutron source. We carried out a systematical analysis for light to heavy materials. As a result, the benchmark performance for neutron spectrum was confirmed to be acceptable, while for $$gamma$$-ray it was not sufficient. This indicates it was effective to use a spectrum shifter. As a shifter beryllium had the best performance. Moreover, it was preliminarily examined whether it is really acceptable that only the spectrum before last collision is considered in the benchmark performance analysis. It was pointed out that not only the last collision but also more previous collisions should be taken into account equally in the benchmark performance analysis.

Journal Articles

Important remarks on latest multigroup libraries

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

Progress in Nuclear Science and Technology (Internet), 2, p.341 - 345, 2011/10

We have already pointed out that the background cross sections and weighting flux are not adequate in multigroup libraries VITAMIN-B6 and JSSTDL-300. This time we examined if the latest multigroup libraries, MATXS-J33, MATJEFF3.1.BOLIB, VITJEFF3.1. BOLIB, VITENEA-J, HILO2k and AMPX file of ENDF/B-VII.0 in SCALE6 and MTXS file in ADS-2.0 have the same problems. The followings are found out from our simple calculations. (1) MATXS-J33 has no problem. (2) VITJEFF3.1.BOLIB, VITENEA-J, HILO2k and AMPX file of ENDF/B-VII.0 in SCALE6 are produced by using the inadequate weighting flux. (3) VITJEFF3.1.BOLIB, MATJEFF3.1.BOLIB and MTXS file in ADS-2.0 have inadequate background cross sections. Note that the self-shielding correction in calculations with VITJEFF3.1.BOLIB, VITENEA-J, HILO2k and AMPX file of ENDF/B-VII.0 in SCALE6, MATJEFF3.1.BOLIB and MTXS file in ADS-2.0 is not always adequate.

Journal Articles

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

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.

Journal Articles

Measurement of reaction rates in Li/V-alloy assembly with 14 MeV neutron irradiation

Tanaka, Teruya*; Sato, Satoshi; Kondo, Keitaro; Ochiai, Kentaro; Murata, Isao*; Takakura, Kosuke; Sato, Fuminobu*; Kada, Wataru*; Iida, Toshiyuki*; Konno, Chikara; et al.

Fusion Science and Technology, 60(2), p.681 - 686, 2011/08

 Times Cited Count:1 Percentile:10.81(Nuclear Science & Technology)

Irradiation experiments of 14 MeV neutrons have been performed on a Li block assembly of 46 $$times$$ 51 $$times$$ 51 cm$$^3$$ with a 5 cm thick V-alloy layer inside to examine the accuracy of neutronics calculations for the Li/V-alloy blanket design. Foils of Nb, Ni, In and Au for reaction rate measurements of $$^{93}$$Nb(n,2n)$$^{rm 92m}$$Nb, $$^{58}$$Ni(n,p)$$^{58}$$Co, $$^{115}$$In(n,n')$$^{rm 115m}$$In, $$^{197}$$Au(n,$$gamma$$)$$^{198}$$Au reactions and $$^6$$Li enriched ($$^6$$Li: 95.5%) and $$^7$$Li enriched ($$^7$$Li: 99.9%) Li$$_2$$CO$$_3$$ pellets for tritium production rate measurements were installed in the assembly. Results of the measurements were compared with those of calculations with MCNP5, JENDL-3.3 and JENDL/D-99. The comparisons for the reaction rates in the Nb, Ni and In foils indicate that measurements and calculations of the fast neutron transport are consistent almost within 10%. In the comparison for the reaction rates in the Au foils, the underestimation of 15% was found at a surface of the V-alloy layer. There is a possibility that this is due to the elastic scattering cross section of V around 4 keV as previously reported. The comparisons for tritium production rates in the $$^6$$Li enriched and $$^7$$Li enriched Li$$_2$$CO$$_3$$ pellets indicate that calculated rates were larger than results of the measurements by 2-8% and 1-4%, respectively.

Journal Articles

Measurement of charged-particle emission double-differential cross section of fluorine for 14.2 MeV neutrons

Kondo, Keitaro; Murata, Isao*; Ochiai, Kentaro; Kubota, Naoyoshi*; Miyamaru, Hiroyuki*; Konno, Chikara; Nishitani, Takeo

Journal of Nuclear Science and Technology, 48(8), p.1146 - 1157, 2011/08

 Times Cited Count:3 Percentile:26.3(Nuclear Science & Technology)

We carried out a detailed measurement of the double-differential cross sections of fluorine for emitted protons, deuterons, tritons and $$alpha$$-particles with 14.2 MeV neutron incidence. An improved charged-particle spectrometer with a pencil DT-neutron beam furnished at the FNS facility of Japan Atomic Energy Agency enabled us to obtain precise data with a fine energy resolution in wide energy range and angular range from 15 to 150 $$^{circ}$$. The obtained data were compared with the nuclear data evaluated in JENDL-3.3 and ENDF/B-VII.0. As a result, large differences in the energy and angular distributions of emitted particles and the charged-particle production cross sections were found between the measured and evaluated data. Angular-differential cross sections for several discrete peaks corresponding to excited states of residual nuclei were extracted to discuss the reaction mechanism of charged-particle emission. The obtained data suggest that the charged-particle emission reaction of fluorine has a quite complicated mechanism where both the direct reaction process and the pre-equilibrium process contribute. The present experiment is the first simultaneous measurement of the four different kinds of charged particles and would provide useful data to confirm previous experimental data as well as to establish a nuclear reaction model of fluorine.

Journal Articles

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

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

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.

Journal Articles

DT neutronics benchmark experiment on lead at JAEA-FNS

Ochiai, Kentaro; Kondo, Keitaro; Onishi, Seiki; Takakura, Kosuke; Sato, Satoshi; Abe, Yuichi; Konno, Chikara; Suzuki, Chihiro*; Yagi, Takahiro*

Journal of the Korean Physical Society, 59(2), p.1953 - 1956, 2011/08

 Times Cited Count:3 Percentile:27.8(Physics, Multidisciplinary)

Lead is an important candidate material as multiplier of nuclear fusion reactor. Few DT neutron integral benchmark experiments were performed for lead so far. Therefore, we have carried out an integral benchmark experiment on lead at the DT neutron source facility of JAEA, FNS. A cubic lead assembly on a side of 45.3 cm was set up and was irradiated with the DT neutron source. Reaction rates of the $$^{27}$$Al(n,$$alpha$$)$$^{24}$$Na, $$^{93}$$Nb(n,2n)$$^{rm 92m}$$Nb, $$^{90}$$Zr(n,2n)$$^{89}$$Zr and $$^{115}$$In(n,n')$$^{rm 115m}$$In reactions were measured as fast neutron spectrum indices in the assembly. A small NE213 spectrometer was also used for measurement of neutron spectra in the assembly. A Monte Carlo calculation code, MCNP5, was adopted to calculate the above neutron spectra and activation reaction rates. Nuclear data libraries, JENDL-3.3, ENDF/B-VII.0, JEFF-3.1 and FENDL-2.1, were used in the calculation. The calculation results of the three libraries except for JENDL-3.3 agreed with the measuring ones. In case of JENDL-3.3, some remarkable disagreements were found. From our investigations, it was pointed out that the inappropriate evaluation of the (n,2n) and inelastic cross sections of lead in JENDL-3.3 caused such disagreement.

Journal Articles

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

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 $$^{115}$$In(n,n')$$^{rm 115m}$$In, $$^{197}$$Au(n,$$gamma$$)$$^{198}$$Au and $$^{6}$$Li(n,$$alpha$$)T reactions and a $$^{235}$$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 $$^{235}$$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.

Journal Articles

Neutron flux measurements in ITER-TBM simulating assemblies by means of multi-foil activation method

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

Progress in Nuclear Science and Technology (Internet), 1, p.142 - 145, 2011/02

Nuclear performances of the ITER Test Blanket Module (TBM) can be calculated with a neutron transport code and nuclear data library. Neutron flux spectra in the TBM should be measured in order to validate the calculated nuclear performances of the TBM. The multi-foil activation method (MFAM) is considered to be one of the most prospective candidates for the neutron flux spectrum measurement. We have examined to measure neutron flux spectra in TBM simulating assemblies with a DT neutron source by using MFAM. We deduced neutron flux spectra in the simulated assemblies with a Monte Carlo code MCNP4C, some nuclear data and unfolding code NEUPAC. The results indicated that the adjusted neutron flux was reasonable for fast neutrons and that measured reaction rate data of more (n,$$gamma$$) reactions were necessary for more adequate adjustment for slow neutrons.

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