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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.

The current status and the progress of research and development (R&D) activities for a Fusion DEMO reactor in the National Institutes for Quantum and Radiological Science and Technology (QST) Rokka...

In the Advanced Fusion Neutron Source (A-FNS), an accelerator-driven fusion-relevant neutron source that is planned for development in Japan, a few grams (3.5 g at full power operation) of tritium ...

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 have conducted a conceptual design on the test modules for Advanced Fusion Neutron Source A-FNS. Fusion neutron irradiation tests are performed using a variety of the test modules in A-FNS. We acquire the irradiation data on the fusion reactor materials, based on which the construction phase of the fusion DEMO DT reactor is to be decided. We established basic specifications and concepts on the test modules. Structural design on the test module was conducted taking into account the replacement with the remote handling, and we established the basic structural concept and the replacement methodology. By applying the methodology in this study, only capsules can be easily replaced from the test module. Nuclear analyses were performed for the test module. The maximum value of the neutron displacement damage on the blanket structural material test specimen is 10 dpa in accumulated irradiation for one year, and we can acquire the irradiation data on the cumulative damage of 20 dpa, which is requirement value as the initial irradiation data for the construction of a DEMO reactor, in accumulated irradiation for two years. Thermal analyses were conducted for the test specimens in irradiation, and it was confirmed their temperatures could satisfy the design specifications.

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

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 environment 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.

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.

Using neutrons generated by d-Li reaction in the A-FNS, we analyzed radionuclidic purity of technetium-99m (99mTc). It is one of the most-used medical isotopes and the daughter radionuclide of molybdenum-99. The angular distribution of the neutrons by the d-Li reaction is anisotropic, and the high energy neutrons around 14 MeV have strong angular dependence in the forward direction. The high energy neutrons produce various radioisotopes, because their energies are over threshold energies of nuclear reactions. We calculated neutron spectra in the A-FNS test cell by using the Monte Carlo transport code MCNP5 with the extension McDeLicious-11 and the nuclear data library FENDL-3.1d. Using the spectra, activation calculations were performed with the inventory calculation code FISPACT-2010. Ratios of the activity of 99mTc to that of other Tc radioisotopes were evaluated for the cooling time after the neutron irradiation. It was found that the purity met a medical demand after an adequate cooling time because of decrease due to the decay of radioisotopes. In addition, we clarified that the purity became higher after a chemical separation process of Tc.

The alleviated limits of impurities of nitrogen and hydrogen isotopes in lithium are suggested to be 400wppm and 550appm, respectively for early realization of Advanced Fusion Neutron Source planned in Japan. The applicability of the suggestion is discussed by comparing to that of IFMIF. As the results, not less than 4-year buffer for R&D of nitrogen trap are brought in, which is thought as one of bottle neck. Additionally, the application of this suggestion would diminish the beryllium (a radioactive isotope will generate in A-FNS process) concentration in processing lithium, as well. On the other hand, it is indicated that there would be no fatal problems by application of the present suggestion.

A purification system for lithium loop is one of critical issues to design the accelerator-driven (IFMIF-type) fusion neutron source. It is written in IFMIF Intermediate Engineering Design Report that the levels of nonmetallic impurities such as nitrogen, oxygen, carbon, hydrogen isotopes and tritium should be less than 10, 10, 10, 10 and 1 wt.ppm, respectively, although there is little basis reported. To achieve the above impurities levels, especially nitrogen and hydrogen isotopes including tritium, it takes long time for purification before the main operation which generate neutron, and the data for these purification systems are so far insufficient to make an execution drawing. Therefore, a purification plan of lithium loop for Advanced Fusion Neutron Source (A-FNS) is suggested for early realization of A-FNS in Japan as below. In the suggested plan, the impurities levels of nitrogen and hydrogen isotopes including tritium are eased to 400 and 80 wt.ppm, respectively, while oxygen and carbon are the same as above. It is considered that the problems of nitrogen impurities would be plugging and erosion/corrosion, and those of hydrogen isotopes be plugging and tritium inventory in lithium. However, it is considered that the plugging would not be brought about, and the erosion/corrosion and the tritium inventory would not become critical to the lithium loop system under the operation temperature between 523 to 573 K and under the suggested impurities level. As the results, it is found that only a cold trap system for the purification system is necessary at first, and the hot trap system including nitrogen trap and hydrogen trap would become necessary after 4 or 5 years operation. That is, the adoption of the present suggestion could bring 4 to 5 years extension for the completion of the purification system in the execution drawing.

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』

A conceptual design of A dvanced F usion N eutron S ource, A-FNS, has been conducted to achieve early realization of fusion-like neutron irradiation test for fusion reactor materials in Japan. A-FNS provides eight test modules to obtain irradiation data for fusion reactor materials. Conceptual design activities on Blanket Functional Materials Test Module (BFMTM), Tritium Release Test Module (TRTM) and Activated Corrosion Products Module (ACPM) were described among the A-FNS test modules. Also, basic concepts of the sub-system cells for the TRTM and the ACPM were also discussed.

In A-FNS, an accelerator-driven fusion-relevant neutron source, a few grams (3.5 g at full power operation) of tritium will be generated every year mainly in lithium target system. Since the generated tritium would migrate out of lithium target system, it is necessary to estimate the tritium migration in and out of the lithium target system for the design of detritiation systems for A-FNS, and therefore, a preliminary estimation is performed in the present study. As the results, it is found that almost all of the generated tritium in lithium target system would be trapped in impurity removal system, while less than 0.5% of that would migrate out. It is also indicated that the amount of tritium that would migrate out of lithium target system would be able to process with the existing techniques so far., Technology of Fusion Energy (TOFE2020)

核融合原型炉の実現に必要な材料照射試験を実施する中性子源として、40MeVまで加速した125mAの重陽子ビームを液体リチウムターゲットに当て大量の14MeV相当の高速中性子を発生させる加速器駆動型核融合中性子源A-FNSが、日欧の国際協力で進めている国際核融合材料照射施設の工学実証・工学設計活動（IFMIF/EVEDA）の成果をベースにして、量子科学技術研究開発機構六ヶ所核融合研究所において計画されている。中性子発生率は、6.8×1016 n/秒であり、発生する高速中性子を用いて核融合炉構造材料の照射試験や核融合原型炉に必要な機能材料等の試験を行うだけでなく、Mo99などの医療用RIの製造、シリコン半導体の製造、高速中性子イメージング等の可能性の検討を行なっている。国内の基礎研究・産業・医療・エネルギー応用までを網羅する汎用性の高い高速中性子照射場を提供し、新たな中性子研究・産業への展開を目指している。 2020年に概念設計が完了し、今後工学設計及び工学実証を経て、2025年頃にA-FNSの建設判断を行うことになっている。, 日本中性子科学会第20回年会

量子科学技術研究開発機構六ヶ所核融合研究所では、核融合炉材料照射試験を実施するための核融合中性子源A-FNSの設計活動を進めている。A-FNSでは、核融合関係の照射試験だけでなく、様々な産業応用を実施したいと考えている。そのひとつとして、A-FNSのd-Li反応で発生する中性子を用いて、100Mo(n,2n)99Mo反応による医療用RIである99Moの製造を行うことを検討している。99Moは核医学診断で最も用いられている99mTcの親核である。現在、日本では海外の原子炉で製造されたものを全量輸入して用いており、99Moの国産化が望まれている。加速器中性子による99Mo製造は比放射能が低くなるが、ウランを用いることなく99Mo製造を行えるメリットがある。照射用の装置であるRI生成モジュールの概念設計では、照射シナリオ、試料の冷却、放射線遮蔽、遠隔保守性などを考慮して設計を実施し、Liターゲットに近い位置に設置することを検討している。我々はモンテカルロ計算コードMCNPを用いた計算によりA-FNSでの99Moの製造量を調べ、日本の需要量である84 TBq/weekを賄う程度の99Moの製造能力があることを示した。また、同時に実施する核融合炉材料照射試験への影響が懸念されるが、99Mo製造に5 mm厚程度の薄い試料を用いることで、1％程度の影響しか与えないことを示した。本発表では、RI生成モジュールの概念設計と本モジュールを用いた99Mo製造検討について報告し、99Mo以外の医療用RIの製造や、RI生成モジュールを用いた中性子計測など、それ以外の展開についても述べる。, 日本中性子科学会第20回年会

Liquid lithium, a candidate material for the target of International Fusion Material Irradiation Facility (IFMIF), easily contains nitrogen. Nitrogen in liquid lithium should be removed as it accelerates corrosion of tubing materials. Hot trapping by iron-titanium alloys is expected to be a practical method. In order to understand the characteristics of nitrogen trapping with iron-titanium alloys in liquid lithium, nitrogen distribution was observed by Soft X-ray Emission Spectroscopy (SXES). Samples of Fe-5Ti alloys were immersed for 9–256 hours in liquid lithium which contains 1000 w-ppm of nitrogen at 823 K and studied by X-ray Powder diffraction and SXES. The results show that nitrogen is trapped mainly in the grain boundaries and on the surfaces of the Fe-5Ti alloys and diffuses in Fe-5Ti much faster than in pure titanium. In addition, it is thought that the amount of nitrogen trapping by the surface of the alloys does not depend on the immersion time., 31st Symposium on Fusion Technology (SOFT2020)

核融合原型炉の実現に必要な材料照射試験を実施する手段として、40MeVの重陽子ビームを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加速器駆動型核融合中性子源（IFMIF）の工学実証・工学設計活動（IFMIF/EVEDA）が日欧の国際協力の下で実施されている。量研は実施機関として、IFMIF原型加速器を六ヶ所核融合研究所に欧州と共同で建設し、連続した重陽子ビームを125mA、9MeVまで加速する実証試験を実施している。また大電流の重陽子ビームのターゲットとなる高速液体リチウム流の安定生成を実証する実規模のリチウム試験ループを製作し、長時間にわたる安定的な液体リチウム流を2014年に実証した。これらの成果を基に、核融合原型炉開発ロードマップに従い核融合中性子源A-FNSの概念設計を進め、2020年に概念設計書を完成させた。A-FNSの基本コンセプトは、加速器系はIFMIFの1ライン分（125mA）とし、IFMIFの中間工学設計をベースにしている。国際協力で進めるIFMIF/EVEDAの成果を活用しA-FNSの加速器系として再構築した。ターゲット系はIFMIF/EVEDAの成果を反映させた。照射モジュール系は核融合材料試験用として日本独自案として９種類のモジュールの検討を実施した。ターゲット系メンテナンスや試験材料の交換などについては高放射線量下での作業となるため、遠隔保守システムの検討を実施した。またA-FNSは、中性子の医療・産業利用も視野に入れた多用途中性子源としている。, 第17回日本加速器学会年会

核融合中性子源A-FNSは、d-Li反応による～7E16 n/sec CW（目標値）のDT核融合ライクなエネルギースペクトルを有する中性子を発生する強力中性子源であり、現在概念設計を終えて工学設計に向けた準備を進めている。A-FNSにおける加速器の役割は、重陽子ビームを生成、加速し、所定の長方形断面形状に整形して液体Liターゲットに入射することである。発生中性子エネルギーに対する要求から重陽子ビームエネルギーは40 MeV、中性子束に対する要求からビーム電流は125 mA CW、年間中性子フルエンスに対する要求から87 %の高い可動率が求められる。要求されるビーム電流は従来の陽子／重陽子加速器での達成値を超える高い目標値であり、その工学実証のため上流部9 MeVまでのプロトタイプであるIFMIF原型加速器LIPAcの建設が進められている。現在までに低デューティではあるもののRFQ出口で所期の5 MeV、125 mAの重陽子ビーム加速に成功した一方、放射化の評価など今後の高デューティ試験における課題も残されている。また、後段SRF Linacにおける～2E-7 /mの低ビーム損失率の要求などLIPAcにおいては検証が難しい課題もある。A-FNS加速器の工学設計に向けて、今後LIPAcで検証すべき課題、期待される成果や、その結果として必要となるかもしれない代替設計の概念について議論する。, 第17回日本加速器学会年会

Introduction: Multiple primary malignancies (MPMs) are likely to develop in patients with colorectal cancer (CRC); however, their prognoses are unclear. This study aims to investigate the prognostic impacts and clinicopathological features of multiple CRCs and extracolorectal malignancies (EMs) with CRC. Methods: We retrospectively evaluated a total of 22,628 patients with stage I–III CRC who underwent curative resection at 24 referral institutes in Japan between January 2004 and December 2012. MPMs were classified as synchronous CRCs (SCRCs), metachronous CRCs, synchronous EMs (SEMs), and metachronous EMs. Results: The presence of SCRCs (odds ratio 1.54, p < 0.001) was independently associated with SEMs in the multivariate analyses. SEMs were the strongest poor prognostic factor for OS (hazard ratio [HR] 2.21, p < 0.001) and RFS (HR 1.69, p < 0.001) compared with age, sex, and primary T and N factors. The incidence of stomach cancer was the highest in EMs, followed by lung, breast, and prostate cancers. Multiple CRCs were evenly distributed throughout the right-side colon to the rectum. Discussion/Conclusion: SEMs were a strong poor prognostic factor for patients with stage I–III CRC. Patients with CRC, particularly those with SCRCs, should be surveyed for SEMs, especially for stomach and lung cancers.

Using neutrons generated by d-Li reaction in the A-FNS, we analyzed radionuclidic purity of technetium-99m (99mTc). It is one of the most-used medical isotopes and the daughter radionuclide of molybdenum-99. The angular distribution of the neutrons by the d-Li reaction is anisotropic, and the high energy neutrons around 14 MeV have strong angular dependence in the forward direction. The high energy neutrons produce various radioisotopes, because their energies are over threshold energies of nuclear reactions. We calculated neutron spectra in the A-FNS test cell by using the Monte Carlo transport code MCNP5 with the extension McDeLicious-11 and the nuclear data library FENDL-3.1d. Using the spectra, activation calculations were performed with the inventory calculation code FISPACT-2010. Ratios of the activity of 99mTc to that of other Tc radioisotopes were evaluated for the cooling time after the neutron irradiation. It was found that the purity met a medical demand after an adequate cooling time because of decrease due to the decay of radioisotopes. In addition, we clarified that the purity became higher after a chemical separation process of Tc.

The latest beta version of ENDF/B-VIII, ENDF/B-VIIIβ4 was released in February 2017 from the Cross Section Evaluation Working Group. We benchmarked the iron and concrete shielding experiments with 40 and 65 MeV neutrons at QST/TIARA by using ENDF/B-VII.1, JENDL-4.0/HE and ENDF/B-VIIIβ4 to investigate whether the 56Fe and 16O data in ENDF/B-VII.1 were properly improved in ENDF/B-VIIIβ4 or not. The drastic overestimation in the calculated result with ENDF/B-VII.1 was resolved in that with ENDF/B-VIIIβ4 in the iron experiment with 40 MeV neutrons, because of the revision of the non-elastic scattering cross section data of 56Fe in ENDF/B-VIIIβ4. However, the calculated result with ENDF/B-VIIIb4 significantly underestimated the measured one in the experiment with 65 MeV neutrons. The drastic overestimation in the calculated results with ENDF/B-VII.1 still appeared in those with ENDF/B-VIIIβ4 in the concrete experiments with 40 and 65 MeV neutrons, due to no improvement of 16O data particularly above 20 MeV in ENDF/B-VIIIβ4. We figured out that the effect of the 16O data replacement was very large and those of 28Si and 27Al data replacements were also not so small. The official release of ENDF/B-VIII should be produced based on this study.

We proposed the neutron spectrum measurement system for Advanced Fusion Neutron Source (A-FNS). It is configured with fission chambers, Self-Powered Neutron Detectors, neutron activation systems using water flow, and activation monitors. In this study, we mainly investigated the multiple activation foils which are sensitive to high energy neutrons. We selected 14 main dosimetry threshold reactions based on specific A-FNS usage conditions. The reactions are as follows: 55Mn(n,2n)54Mn, 59Co(n,p)59Fe, 59Co(n,2n)58Co, 59Co(n,3n)57Co, 75As(n,2n)74As, 89Y(n,2n)88Y, 93Nb(n,2n)92mNb, 169Tm(n,2n)168Tm, 169Tm(n,3n)167Tm, 197Au(n,2n)196Au, 197Au(n,3n)195Au, 209Bi(n,3n)207Bi, 209Bi(n,4n)206Bi, and 209Bi(n,5n)205Bi. The dosimetry reaction rates were calculated using Monte Carlo code MCNP-5.15 with McDeLicious-11 and nuclear data libraries FENDL-3.1c, IRDFF-1.05 and EAF-2010. As for neutron-induced cross section data of the reactions in the high energy region, we clarified that there were limited experimental data, and proposed new experiment for their evaluations. Keywords: A-FNS, Neutron spectrum measurement, Activation foil, Dosimetry cross section

Liquid lithium, a candidate material for the target of International Fusion Material Irradiation Facility (IFMIF), easily contains nitrogen. Nitrogen in liquid lithium should be removed as it accelerates corrosion of tubing materials. Hot trapping by iron-titanium alloys is expected to be a practical method. In order to understand the characteristics of nitrogen trapping with iron-titanium alloys in liquid lithium, nitrogen distribution was observed by Soft X-ray Emission Spectroscopy (SXES). Samples of Fe-5Ti alloys were immersed for 9–256 h in liquid lithium which contains 1000 w-ppm of nitrogen at 823 K and studied by X-ray Powder diffraction and SXES. The results show that nitrogen is trapped mainly in the grain boundaries and on the surfaces of the Fe-5Ti alloys and diffuses in Fe-5Ti much faster than in pure titanium. In addition, it is assumed that the amount of nitrogen trapping by the surface of Fe-5Ti alloys does not depend on the immersion time.

A new benchmark experiment on lead with DT neutrons was designed and carried out with a large lead assembly covered with Li2O blocks at JAEA/FNS to validate nuclear data of lead for measurement of ...

Advanced Fusion Neutron Source (A-FNS) [11] is an accelerator-based neutron source utilizing Li(d,xn) nuclear stripping reactions to simulate D-T fusion neutrons for testing and qualifying structural and functional materials of fusion reactor components, which is to be constructed at the Rokkasho site of National Institutes for Quantum and Radiological Science and Technology, Japan, in the near future. The purpose of the study reported here is to demonstrate the ultimate safety margins of A-FNS in the worst case of release of radioactive materials outside the A-FNS confinement system. For this purpose, we analyzed a ‘bounding event’ postulated in A-FNS. The postulated event sequence consists of fire of the purification system of the liquid Li loop during the maintenance, of mobilization of the tritium and 7 Be, which are the impurities of the loop, and of the entire loss of confinement of the radioactive materials. We have calculated the early doses to the public due to the release of the tritium and 7 Be source terms to the environment. The UFOTRI/COSYMA simulations have been performed considering the site boundary of 500 m away from the facility. The obtained results indicate that the early dose is below the level that requires the emergent public evacuation. Such results demonstrate that the A-FNS complies with the defined safety objective against its radiation hazard. The simulation results suggest that the inherent, ultimate safety characteristic found by this study may assist a licensing process for installation of A-FNS.

Advanced Fusion Neutron Source (A-FNS) is based on a 40 MeV, 125 mA deuteron accelerator with liquid Li target. Now, we are performing conceptual designs of A-FNS and its test modules. A-FNS provides 8 kinds of test modules for fusion reactor materials. In this study, we newly design the test modulus on Blanket Functional Material Test Module (BFMTM), Tritium Release Test Module (TRTM), and Activated Corrosion Product Module (ACPM). In the BFMTM, we irradiate the small rectangular test specimens of lithium titanate oxide and beryllide, which are the functional materials of the Japanese DEMO blanket. It is located at behind of the other test module, which is designed for irradiation test of the blanket structural material, F82H. We design the rectangular vessel, the honeycomb vessel and the cylindrical capsules for BFMTM. The honeycomb vessel concept is similar to a fuel rod of a fast breeder reactor. Total 47 cylindrical capsules (5 rows in beam direction, 9-10 capsules in each row) are installed in the honeycomb vessel, and the honeycomb vessel is installed in the rectangular vessel. The irradiation temperatures are controlled from 300 to 1000 ºC by an electrical heater and helium gas. The helium gas flow, its temperature and the temperatures of the capsules are measured by the on-line measurement. After the irradiation, all specimens are delivered to PIE facility by remote handling. Nuclear performance has been calculated using MCNP. The maximum neutron irradiation damage of Be is 0.8 dpa/fpy in the capsule, and the design target of 2 dpa can be achieved by 3 fpy irradiation. In the TRTM, we irradiate the small pebbles of the functional materials of the DEMO blanket and measure the tritium release and recovery properties by the on-line measurement. It is located at 30 cm away from the BFMTM in beam direction. The pebbles are packed in the cylindrical capsules of nickel alloy. The electrical heater is surrounding the capsules. Tritium permeation gap and helium flow gap are installed around the pebble packed vessels. Rig cylinders of SS316L or F82H are provided between the gaps. The irradiation temperatures are controlled from 300 to 1000 ºC, the interval temperature is 100 ºC. Total 16 cylindrical capsules (8 capsules each irradiation temperature for lithium titanate oxide and ones for beryllide) are installed in the module. We evaluated tritium production rates in each capsule by MCNP and confirmed that the values were measurable using a commercially instrument such as an ionization chamber. In the ACPM, we irradiate the F82H cooling water pipes. High-temperature and high-pressure water (300 ºC, 15 MPa), which are same condition as the DEMO blanket, flows in the pipes. We measure the ACPs in the F82H pipes by the on-line measurement of the water quality. The location of ACPM is same to that of BSMTM under three damage conditions, 4, 6 and 10 dpa/fpy. The irradiation time conditions are 100, 400, 900, 1600 and 3000 hours. The water quality measurement system is installed at a downstream area of each capsule to trap and measure the sample by ICP-MS. After the irradiation, the pipe specimens are delivered to PIE facility and are measured ACPs (elution ion, particulate oxide, etc.)., 第19回核融合炉材料に関する国際会議(ICFRM-18)への出席

Advanced Fusion Neutron Source (A-FNS) is an accelerator-driven (IFMIF-type) fusion neutron source to offer fast neutrons to study irradiation effects on fusion reactor materials, which is to be sited at Rokkasho, Japan. A-FNS should be designed so that radiation safety is assured for workers and the public with compliance of the Japanese radiation safety regulation, that was revised in 2017. The revision that should be accounted for the A-FNS conceptual and forthcoming engineering design is that “safety provisions should be made a priori for emergency situations.” We present safety requirements, safety functions and associated safety analysis of the A-FNS conceptual design. We have developed safety requirements for the A-FNS design, which are in compliance not only with the revised Japanese regulation but also to the international nuclear/radiation safety standards. Numerical project guidelines are presented, which satisfy the safety requirements for radiation safety of workers and the public. We have analyzed a “bounding accident case” of A-FNS at Rokkasho, in which all the amount of the major mobilizable radioactive materials, i.e. beryllium-7 in the target liquid lithium loop, are released to the environment. We performed a site-specific dose analysis using meteorological data observed at Rokkasho. The simulation result indicates that the early dose to the public (for a week) 200∼300 m away from the release point is 1∼2 orders of magnitude smaller than the IAEA guideline for emergent evacuation of the public, 100 mSv., 14th International Symposium on Fusion Nuclear Technology

Liquid lithium (Li) jet is planned as a beam target in fusion neutron sources (FNSs), such as IFMIF in Japan and EU, A-FNS in Japan and IFMIF-DONES in EU. For the safety and the efficiency of such FNSs, it is desirable to keep the high-speed Li jet stable. In addition to many experimental researches, numerical approaches using CFD simulation have been also required to evaluate the detailed flow pattern inner the Li jet because of the opacity. In our previous simulation, it was found that the vortex structure under the free surface of the Li jet had the strong influence on the surface fluctuation using LES simulation. In this study, for evaluating the interaction between the Li surface behavior and the flow pattern inner the Li jet, two simulations are conducted: one is the LES simulation considering wall roughness, and another one is the RANS simulation using full-scale model with the nozzle and the Li jet. The influence of wall roughness on the vortex structure becomes an issue in long-term operation of actual FNSs, and the influence of the secondary flow generated due to the side wall on the surface shape is evaluated in the latter simulation., 14th International Symposium on Fusion Nuclear Technology

A-FNSでは、ブランケット構造材、ブランケット機能材、ダイバータ機能材、ブランケットぺブル充填層からのトリチウム放出回収特性、計測制御機器、ブランケット第一壁高温高圧水配管中の放射化腐食生成物、ブランケット核特性に関する照射データを取得する。A-FNSで実施する試験モジュールの目的、基本概念、設計条件、実験方法、照射計画を検討した。ブランケット構造材料試験モジュールに関する概念設計を行った。試験モジュールの交換は遠隔機器により行われ、交換前に試験セルに隣接するアクセスセルで配管及び計装線を切断してから、試験セル壁内に設置する遮蔽プラグと一体化して試験モジュールを水平方向に引き抜く。遠隔保守による交換を考慮した試験モジュールの基本構造概念を確立した。, 14th International Symposium on Fusion Nuclear Technology

本研究では、A-FNS定常運転状態におけるトリチウムの一次移行挙動評価と、必要なトリチウム処理系に関する検討を実施した。トリチウムの一次移行挙動評価の結果、生成するトリチウムのほとんどは液体リチウム純化系の水素トラップあるいはコールドトラップに移行し固定化される一方で、配管等を透過し、ループ建屋内や真空排気系に移行することを明確にし、その評価数量を用いてA-FNSリチウムループ建屋に必要なトリチウム処理容量および排気風量の評価を実施した。, 日本原子力学会2019年秋の大会

核融合中性子源A-FNSの設計に関する日本の主な活動として、2035年頃の原型炉建設判断までに核融合中性子源によるブランケット構造材料である低放射化フェライトF82H鋼の20dpaまでの初期照射データを取得する必要がある。そのため、A-FNSでブランケット構造材料試験モジュール（BSMTM）を用いて照射試験により、F82H鋼の初期照射データとして250℃～550℃、積算～20dpaを取得する計画であり、ターゲット背後の最近傍の高中性子束場に設置するBSMTMの概念設計を進めている。本成果報告では、ハニカム円筒型キャプセルを用いたBSMTMの基本構造の概念設計、及び核的特性評価、温度特性評価、核変換生成ガスに対する耐圧評価の進捗について発表する。, 日本原子力学会2019年春の年会

核融合中性子源A-FNSの試験モジュールとして、中性子束計測モジュール(NFMM)、F82Hの核融合中性子照射下腐食データを取得する放射化腐食生成物試験モジュール(ACPM)、トリチウム増殖材・中性子増倍材微小球からのトリチウム放出 回収特性試験モジュール(TRTM)、ブランケット機能材料照射試験モジュール(BFMTM)に関する基本概念を検討した。MCNPによる核解析を実施し、試験モジュールの核特性を評価し照射条件等を確立したので報告する。, 2019年日本原子力学会春の年会