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The current status and the progress of R&D activities for a Fusion DEMO reactor in the QST Rokkasho Fusion Institute is reported. In order to advance the JA DEMO activity, not only Japanese domestic activity but also international collaborations of Broader Approach Activity and ITER related activities are conducted in the QST Rokkasho Fusion Institute. Activities for DEMO design and relevant R&D, design of a fusion neutron source and development of an accelerator, ITER-TBS, tritium handling technology and information technology infrastructures including a supercomputer system and a remote experimentation system are carried out for a Fusion DEMO reactor.

核融合中性子源A-FNSに関する遮蔽設計において、照射を実施する試験セルの横に設置される側方アクセスセルでは遮蔽プラグのスリット部や配管を通した放射線ストリーミングが問題となりうる。また、加速器からのビームダクトは、リチウムターゲットを直視しており、発生した中性子の後方のストリーミングによる線量上昇が懸念される。試験セルの周囲の部屋においても、ゾーニングや設置機器の耐放射線性の検討などのために線量評価が必要である。モンテカルロ計算コードMCNPを用いて、これらの線量を計算した。本講演会にて、これらの評価結果について報告する。, 第14回核融合エネルギー連合講演会

In order to assess radiation damage of a fusion material before a decision of Japanese fusion DEMO reactor construction, we have been designing an intense d-Li neutron source facility, Advanced Fusion Neutron Source (A-FNS) in Japan. A-FNS will be constructed before 2025. The main purpose of A_FNS is to acquire radiation damage data of the fusion material under fusion-like neutron irradiation testing. One of the characteristics of A-FNS is that large amounts of high energy neutrons (> MeV) are produced with an expected intensity around 6.8 x 10^16 n/s. In this study, we propose a neutron measurement system that is configured with multiple threshold reaction activation foils that are sensitive to high energy neutrons. The need to measure the cross-section data for the threshold reactions is also discussed.

We found out that probability table (p-table) data for heating number in the FENDL-3.1d ACE files for 33 nuclei included negative values. Thus we investigated its reason in detail. As a result, it was specified that the reason was that partial KERMA factors of the radiative capture reaction became too large, because the energy-balance was broken or NJOY did not treat secondary gammas of a special format. We proposed two solutions for this issue; 1) to modify NJOY so as to calculate partial KERMA factors with the kinematics method, 2) to set p-tables for heating number to “1.0” or average heating numbers. New ACE files of FENDL-3.1d produced with the two solutions had no negative p-tables for heating number.

The Linear IFMIF Prototype Accelerator (LIPAc) is designed to provide 125mA CW Deuteron beams at 9MeV. This series reports on the commissioning of the LIPAc. This work focuses on the optimization, aided by genetic algorithm, of transport optics to perform energy spread measurement after the Radio Frequency Quadrupole (RFQ) module., 2022年日本原子力学会春の年会

日本の核データライブラリーJENDL-5が2021年末に公開される。JAEA/FNSで実施した積分実験を用いて核融合中性子源A-FNSでも照射試験される予定の銅及びγ線の遮蔽体として重要な鉛核データのベンチマークテストを実施した。特に約10年間使われてきた前バージョンであるJENDL-4.0からの比較を中心に、改善点などを報告する。, 2022年日本原子力学会春の年会

日本の核データライブラリーJENDL-5が2021年末に公開された。JAEA/FNSで実施した積分実験を用いて核融合中性子源A-FNSでも照射試験される予定のトリチウム増殖材に含まれるチタンの核データのベンチマークテストを実施した。前バージョンであるJENDL-4.0からの比較を中心に報告した。, 日本原子力学会2022年春の年会

Construction and validation of the Linear IFMIF Prototype Accelerator (LIPAc) have been conducted under the framework of the IFMIF/EVEDA project. The LIPAc consists, in its final configuration, of a 100 keV injector and the world longest 5 MeV RFQ accelerator, followed by a MEBT with high space charged and beam loaded re-buncher cavities, an HWR-SRF linac, HEBT with a Diagnostic Plate, ending in a Beam Dump (BD) designed to stop the world highest deuteron current of 125 mA CW at 9 MeV. The beam commissioning at a low duty cycle of ~0.1 % led to a successful RFQ acceleration of 125 mA and 5 MeV beam in 2019. The following beam commissioning phase was initiated in July 2021 with a temporary transport line replacing the SRF linac. The major goals of this phase are to validate the RFQ, MEBT and BD performances up to CW and to characterize the beam properties in preparation to the final configuration with the SRF linac. This paper will present progresses made in this phase so far, such as a low-current and low-duty beam commissioning completed in Dec. 2021, CW operation campaign of the injector towards the nominal beam current, and RF conditioning of the RFQ towards CW., Proceedings of the 31st International Linear Accelerator Conference, LINAC2022, Liverpool, UK

核融合中性子源(A-FNS)で核融合炉材料の中性子照射試験を行う試験モジュールの設計と照射試験計画に関して紹介する。A-FNSでは、原型炉建設判断移行のための初期照射データを2035年頃までに取得する計画である。ブランケット材やダイバータ材、計測制御機器材等の照射データ取得のための9種類の試験モジュールの概念設計を行った。これらの試験モジュールは、試験セル側壁の遮蔽プラグと一体化した構造で設計し、試験モジュール交換の際には、試験モジュールと遮蔽プラグを一体化しながら、水平方向に、側方アクセスセルに搬送する。多くの試験モジュールは概ね共通化した構造で設計し、材料試験片を円筒型キャプセル内に装填する。ブランケット構造材であるF82Hの微小試験片に関しては10dpa/fpyで照射し、積算2年間の照射で、20dpaの初期照射データを取得する計画である。, ICFRM-20

Recently we tested the official ACE files of TENDL-2015 and found the following problems in the files, a)�� no p-table data except for those of 235U, 235mU and 238U in the neutron sub-library, b) no secondary gamma data for a lot of nuclei in the neutron, proton, deuteron, triton, He-3, and alpha sub-libraries. By a simple calculation, it was demonstrated that effects of the issues were not so small as follows, i) �the effect of no unresolved resonance data in ACE files was large in a special case as pure niobium, ii) secondary gammas produced in neutron-gamma coupling MCNP calculations were not correct because wrong data were used as secondary gamma data. The issues were probably caused by simple mistakes of NJOY processing. Note that the issues also occur partially in the official ACE files of TENDL-2017.

A key conception of the remote maintenance (RM) method is presented of the target assembly (TA) of Advanced Fusion Neutron Source (A-FNS), that is an accelerator-driven fusion neutron source utilizing the Li(d,xn) nuclear reactions. The RM method, newly proposed here, is aimed at (i) enhancing the modularity of the TA RM and (ii) keeping the compatibility with the materials irradiation tests, compared to the preceding TA RM design of International Fusion Material Irradiation Facility (IFMIF). A 3-dimensional kinematics simulation indicates that the large clearance of 52 mm between the TA and high flux test module (HFTM) brings the independent removal from and the installation in the test cell, regardless of the presence of the test modules in the test cell. A neutronics performance of the HFTM with the enlarged clearance is also studied. The gradient of the calculated neutron irradiation damage is found to be decreased and satisfies a users’ requirement of the irradiation en- vironment when the clearance is enlarged from 2 to 52 mm. (The former value was the IFMIF engineering design value.) These simulation results suggest that the proposed TA RM method will enhance not only the modularity of the TA, but also will improve the materials irradiation test environment.

Our detailed investigation on the data of iron nuclei in nuclear data library FENDL-3.1d figured out that residual nucleus production yield data just above 20 MeV had a problem, which caused a sharp spike in the DPA cross-section. In addition, we revealed that the same and similar problems occurred the data in other 73 nuclei FENDL-3.1d selected from TENDL- 2010 or TENDL-2011. Thus, we revised the yield data and verified that the sharp spike just above 20 MeV in the DPA cross-section disappeared using the revised data. Moreover, the DPA cross-section data of 49 nuclei in FENDL-3.1d from JENDL/HE-2007 became much smaller sharply above 20 MeV because the nuclei had no energy distribution data of residual nuclei above 20 MeV. Other problems occurred in 13 nuclei of FENDL-3.1d from JEFF-3.1.1 above several MeV, due to wrong energy distribution data of recoil nucleus in the inelastic scatter- ing to continuum states below 20 MeV and no energy distribution data of residual nuclei above 20 MeV. The DPA cross-section data of more than 70% of nuclei in FENDL-3.1d have problems due to non-physical data in the original nuclear data.

The 1st proton beam acceleration of the Linear IFMIF Prototype Accelerator (LIPAc) through its novel RFQ was succeeded on 13th June 2018. Addition to plenty of beam diagnostics equipped in the beam line, we prepared some radiation detectors placed around the accelerator in order to acquire supplemental information of the beam, as an indirect measurement. In the first day of the beam injection to the RFQ, the gamma-rays corresponding to certain excited states of Al of the low power beam dump were successfully detected by a LaBr3(Ce) scintillation detector. Some neutrons, which would originate from the interaction of protons with Cu somewhere, were also observed. These results proved that the beam was certain-ly accelerated up to about 2.5 MeV, and provided us a definitive confidence that the RFQ was working appro-priately from the very beginning of the commissioning. Also, the comparison of the radiation yields with the RFQ transmission provided additional information on the beam energy distribution.

核融合中性子源(A-FNS)試験モジュールの概念設計を行った。A-FNSの概念設計においては、多様な照射データをブレキシブルに取得できる試験モジュール概念の確立及び試験モジュールの遠隔保守設計が重要な設計課題である。本課題を解決するために、照射モジュールの核設計、熱設計、構造設計、遠隔保守設計等を行い、A-FNSの照射モジュールの基本概念を確立し、IFMIFでは想定しえなかった9種類の照射試験モジュールを設計した。また、IFMIFよりも遠隔保守性に優れた遠隔保守方法を提案した。本学会にて、照射モジュールの概念設計の詳細を発表する。併せて、A-FNS施設の建屋及び敷地設計、リチウムターゲットシステムからのトリチウム処理システム、ターゲットの遠隔保守方式等の概念設計について紹介する。, 28th IAEA Fusion Energy Conference (FEC2020)

核融合炉材料照射試験を目的とした核融合中性子源A-FNSを六ヶ所に建設することを目指して設計活動を進めている。A-FNSでは、試験セルと呼ばれる照射を実施するセルに設置するリチウムターゲットアセンブリや試験モジュールなどを、遮蔽プラグと一体として側方のアクセスセルから交換する独自の機器交換方法を検討している。そのため、特に側方アクセスセルへの立ち入り可能性を検討し、放射線管理区域のゾーニングを設定する必要である。遮蔽プラグのスリットおよびヘリウムガス配管からは放射線ストリーミングがあるため、モンテカルロ計算コードMCNPを用いて側方アクセスセルの線量評価計算を実施した。, 第10回IFERC-CSC研究会

核融合原型炉の実現に向けて、核融合反応で発生する14 MeVの高速中性子を模擬し、高速中性子による材料照射試験を実施する手段として、重陽子を40 MeVまで加速しリチウムターゲットに当て大量の高速中性子を発生させるIFMIFの工学実証・工学設計活動が日欧の国際協力の下で実施されている。これらの成果を基に、QSTでは核融合原型炉開発ロードマップに従った材料開発に不可欠な核融合中性子源A-FNSの設計検討を進めている。講演ではQSTで進めている核融合中性子源A-FNS計画について講演を行う。, 研究会『大強度加速器による材料照射施設の可能性』

We have conducted design activities of Advanced Fusion Neutron Source A-FNS in order to perform irradiation tests for fusion materials. We have intended to use A-FNS also for neutron applications because it is an intense neutron source. As one of the applications, we are to conduct medical radio isotope (RI) production such as Mo-99. We have investigated an installation of RI Production Module (RIPM) with a thin plate-like sample for RI production into a gap of a few centimeter between a lithium target and an irradiation module for fusion materials. We have conducted the conceptual design on the RIPM especially by taking the following concerns into consideration: (1) Insertion and ejection of the sample for RI production during irradiation by horizontal transfer between the irradiation test cell and lateral access cell, (2) Cooling of nuclear heating, and (3) Reduction of the radiation streaming. The irradiation tests for fusion materials are performed continuously for a long period over a few months. On the other hand, the period per an irradiation for RI production is a few days. We designed the RIPM with a mechanism by using a servomotor in order to insert and eject the sample for RI production from outside the test cell without stopping a deuteron beam. We introduced helium gas cooling functions to the RIPM to remove the nuclear heating. In order to reduce the radiation streaming through the penetration duct for the RIPM and lessen the radiation level in the lateral access cell, we designed a shielding structure by putting shielding materials such as tungsten in the duct. By using the RIPM, we are also to perform neutron measurement by foil activation method. From the nuclear analyses, it was clarified that a spatial distribution of neutron flux depending on the deuteron beam can be monitored., 31st Symposium on Fusion Technology (SOFT2020)

The Linear IFMIF Prototype Accelerator (LIPAc) is under construction as a collaboration between Europe and Japan for challenging the technical validation of the low energy part up to 9MeV of IFMIF deuteron accelerator unit with 40MeV-125mA CW. The staged installation and commissioning activities are ongoing at the BA site in Rokkasho Fusion Institute of QST, and the commissioning of RFQ is underway. A deuteron beam acceleration at 5 MeV, 125mA was achieved at short pulse (~1 ms pulse duration) at ~1 Hz repetition. Here, ~90 % beam transport was obtained. Here, 8-chains of 175 MHz CW RF sources are connected to the RFQ in parallel. After that, MEBT, D-plate, HEBT and high power beam dump were connected to the RFQ in series, and high duty cycle beam commissioning will be implemented., 30th International Linear Accelerator Conference 2020