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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...

Design, development, manufacturing, and test activities of the RF power system (RFPS) for Linear IFMIF Prototype Accelerator (LIPAc) were completed in Europe. Installation and commissioning activities were carried out at the International Fusion Materials Irradiation Facility-Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) site in Rokkasho, Japan. Challenging IFMIF requirements led to a number of innovations during design and development. Commissioning required a major effort on calibration and fine setting and led to development of new functionalities. The RFPS was validated under full power and 125-mA deuteron beam loading conditions, in the radio frequency quadrupole (RFQ), demonstrating good performance. This article is an overview about how technical challenges impacted the prototype RFPS design and its functional evolution during commissioning, cavity conditioning, and beam operation of the RFQ.

BA協定の下での日欧協力としてQST六ヶ所融合研究所でIFMIF原型加速器（LIPAc）の実証試験が実施されている。 LIPAcでは、超伝導RF（SRF）加速器の試験も計画されており、SRFライナックを冷却するための液体ヘリウムを製造するための冷凍機システムが調達され、六ヶ所研に設置された。この記事では、LIPAc用の冷凍機システムの概要、六ヶ所研における設置作業および動作試験の詳細について述べる。

The eight-chain RF system and radio frequency quadrupole (RFQ) linac were successfully integrated at the facility of the Linear IFMIF Prototype Accelerator (LIPAc). We achieved an unprecedented high current deuteron beam up to 55 mA in pulse operation ( $300~\mu \text{s}$ , 1 Hz). The keys of the success were (1) understanding reflected power from RFQ to RF system, (2) tuning each RF chain individually, (3) intensive RF conditioning for holding the stable RF power in the RFQ, and (4) optimizing the beam loading compensation control. Interestingly, the reflection at the breakdown in RF conditioning was higher than an estimation and reached up to 600 kW so far. In order to avoid damage on tetrodes by the high reflection, the impedance of each circulator was accurately adjusted.

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

現在、核融合エネルギー分野における日本と欧州による共同事業の一つである、国際核融合材料照射施設(IFMIF)の工学実証・工学設計活動(EVEDA)の一環として、原型加速器(LIPAc)の建設が量研六ヶ所核融合研究所で進行中である。高周波四重極加速器(RFQ: Radio Frequency Quadrupole accelerator)の長パルスビーム試験のため、超伝導高周波加速器(SRF: Superconducting Radio Frequency accelerator)を将来設置する箇所に新たなビーム輸送系(MEL: MEBT Extension Line)をクリーンな環境下で構築し、準備を進めている。 SRFを使用する施設では、ゲートバルブの開閉操作で発生・混入する微粒子によって生じるフィールドエミッション(FE)による性能劣化が問題視されている。LIPAcでは微粒子のサイズ・個数とSRFの性能劣化との関係を定量的に評価するのため、真空下で微粒子の動きを可視化できるパーティクルモニタをMELに導入し、ゲートバルブの開閉操作で発生する微粒子の測定を行った。本発表では微粒子測定の方法と結果について報告する。, 第18回日本加速器学会年会

The detailed shielding analysis has been performed in order to find a configuration of the radiation shielding in the accelerator building necessary for the operation of the Linear IFMIF Prototype Accelerator (LIPAc), which is under construction in Rokkasho, Japan, at the full power of 1.125 MW to satisfy the radiation dose limit prescribed by Japanese regulations. The final design of the beam dump constructed by CIEMAT, Spain was fully taken into consideration. The impact of all the features potentially causing neutron streaming were investigated and the optimization of local additional shieldings were conducted. As the result, the most important one was found to be the air ventilation duct shield, which completely covers the ducts and creates an additional labyrinth. By considering the additional shielding configuration determined in the present study, the legal criteria at the controlled area boundary can be completely satisfied.

線形IFMIFプロトタイプ加速器の開発は、EUと日本の国際協力(BA協力）で進められている。2014年11月に入射器で最初の水素ビーム発生後、高周波四重極加速器RFQが設置され、RFQを用いた最初の水素ビーム加速が2018年7月に開始され、2019年3月には最初の5MeV重水素ビーム実験加速実験が行われた。 並行して、RFQの華雄に置かれる超伝導線形加速器SRFリニアックの組立が進行中である。CWビームダンプは既に据え付けられており、CW運用の活動は2020年に開始される。本解説では、IFMIF原型加速器の解説と開発の現場を報告する。

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.

International audience; Design, development, manufacturing, and test activities of the RF power system (RFPS) for Linear IFMIF Prototype Accelerator (LIPAc) were completed in Europe. Installation and commissioning activities were carried out at the International Fusion Materials Irradiation Facility-Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) site in Rokkasho, Japan. Challenging IFMIF requirements led to a number of innovations during design and development. Commissioning required a major effort on calibration and fine setting and led to development of new functionalities. The RFPS was validated under full power and 125-mA deuteron beam loading conditions, in the radio frequency quadrupole (RFQ), demonstrating good performance. This article is an overview about how technical challenges impacted the prototype RFPS design and its functional evolution during commissioning, cavity conditioning, and beam operation of the RFQ.

In summer 2019 the IFMIF/EVEDA Radio Frequency Quadrupole (RFQ) accelerated its nominal 125 mA deu-teron (D+) beam current up to 5 MeV, with 90% transmis-sion for pulses of 1 ms at 1Hz. The Linear IFMIF Prototype Accelerator (LIPAc) is a high intensity D+ linear accelera-tor; it is the demonstrator of the International Fusion Ma-terial Irradiation Facility (IFMIF). In particular the RFQ is the longest and most powerful ever operated. An intense campaign of measurements has been performed in Rok-kasho to characterize several performances of this complex machine: transmission, emittances, energy spectrum and beam loading. The history and the results of the commis-sioning until this important project milestone are here de-scribed. An overview of the foreseen activities to be carried out to reach the CW operation is also presented, 11th international particle Accelerator conference (IPAC'20)

LIPAc is the Linear IFMIF Prototype Accelerator developed within the framework of the IFMIF project under the Broader Approach (BA) agreement signed between EURATOM and the Japanese Government in 2007. The IFMIF accelerator aims to provide an accelerator-based D-Li neutron source to produce high intensity neutron fluxes with appropriate energy spectrum in order to characterize materials envisioned for future fusion reactors. Because the IFMIF accelerator has to reach unprecedented performances, the feasibility is being tested through the design, manufacturing, installation, commissioning and testing activities of a 1:1-scale prototype accelerator, namely LIPAc, from the injector to the first cryomodule together with the High Energy Beam Transport line and the High Power Beam Dump. After outstanding results obtained in 2019, the LIPAc project has entered 2020 in the preparation of the third commissioning stage, i.e., validation in continuous-wave mode of the complete accelerator up to 5 MeV with its final beam dump. The validation until the nominal energy of 9 MeV will be made after the completion of cryomodule assembly. After a brief overview of the goals already achieved in the framework of the IFMIF/EVEDA program, this paper will present a synthesis of the results that have been obtained so far with the LIPAc accelerator as well as the future developments planned beyond 2020., 31st Symposium on Fusion Technology (SOFT2020)

The design of the LIPAc RF Power System main components will be presented in this contribution, including the RF modules, the SSPA (Solid State Power Amplifier) for the re-buncher cavities, the HVPS (High Voltage Power Supply) for the final amplifiers anodes and the RF water cooling system. Additionally, the main difficulties encountered during the first months of the RFPS commissioning and operation will be described, together with the applied improvements., 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

The eight-chain RF system and radio frequency quadrupole (RFQ) linac were successfully integrated at the facility of the Linear IFMIF Prototype Accelerator (LIPAc). We achieved an unprecedented high current deuteron beam up to 55 mA in pulse operation (300 μs, 1 Hz). The keys of the success were (1) understanding reflected power from RFQ to RF system, (2) tuning each RF chain individually, (3) intensive RF conditioning for holding the stable RF power in the RFQ, and (4) optimizing the beam loading compensation control. Interestingly, the reflection at the breakdown in RF conditioning was higher than an estimation and reached up to 600 kW so far. In order to avoid damage on tetrodes by the high reflection, the impedance of each circulator was accurately adjusted.

The IFMIF accelerator facility consists of 2 identical linacs, each accelerating a 125 mA CW deuteron beam up to the energy of 40 MeV. In order to reach these unprecedented performances, the Linear IFMIF Prototype Accelerator (LIPAc) is under installation and commissioning at the International Fusion Energy Research Centre (IFERC) in Rokkasho, Japan, in the framework of the IFMIF/EVEDA project, which is part of the Broader Approach (BA) agreement between Japan and EU. The accelerator is designed to validate components up to 125 mA CW deuteron beam at 9 MeV. The accelerator components of LIPAc have been designed and manufactured mainly by European Institutes. The injector and superconducting linac, RFQ, MEBT, Diagnostics Plate, HEBT and beam dump have been developed respectively by CEA-Saclay, INFN-Legnaro and CIEMAT-Madrid and were delivered to Rokkasho between 2013 and 2016. The commissioning of the injector with beam started in November 2014. This paper dealt with the experimental data obtained with the beam diagnostics of the injector. The electrical measurements of the beam intensity on the beam stopper were compared with calorimetric measurements. The beam profiles measured with a CCD camera and a custom image-intensified CID camera are also addressed. The analysis of beam emittance and ion species fractions from data obtained with an Allison scanner is described and the results of species fraction measurements are compared with those obtained by using a deported spectrometer. Finally, the analysis of beam space potential from data obtained with a 4-Grid analyser is presented.

The construction of the Linear IFMIF Prototype Accelerator (LIPAc) is in progress at Rokkasho, Japan. The important milestone of the project is to commission the necessary components, namely RFQ, MEBT and diagnostics, to accelerate the proton beam up to 2.5 MeV or the deuteron beam up to 5.0 MeV in pulsed mode with a low duty cycle of 0.1%. The detailed radiation safety analysis has been conducted for the beam commissioning with the consideration of the specific radiation source conditions and the building configuration. As a result, it turned out that the dose rate expected outside the accelerator vault during deuteron beam operation at 5 MeV is mostly dominated by the neutron streaming effect through three major penetration sectors, i.e. HVAC ducts, water pipe holes and underground pits, while it is negligibly small during the proton beam operation at 2.5 MeV. It was confirmed that the dose rate expected does not exceed the legal limit for the controlled area boundary and no serious radiological issues exist in the beam commissioning planned.

The construction of the Linear IFMIF Prototype Accelerator (LIPAc) is in progress in order to demonstrate the feasibility of the low energy section of an IFMIF deuteron accelerator up to 9 MeV with a beam current of 125 mA in CW. The next milestone of the project is the so-called Phase-B beam commissioning, and one of the missions is to demonstrate the acceleration of the proton beam up to 2.5 MeV or the deuteron beam up to 5.0 MeV in pulsed mode with a low duty cycle of 0.1% through RFQ. Most of the components and subsystems necessary for Phase-B were delivered by 2016 under the responsibility of Fusion for Energy (F4E) as in-kind contributions of several European institutes, namely CEA (France), CIEMAT (Spain), INFN (Italy), and SCK-CEN (Belgium), and QST is in charge of the installation of the delivered equipment. The installation and check-out of the RFQ subsystem and the RF power system was completed by July 2017, and the RF conditioning of the RFQ cavity started. Also, the installation and the check-out of the important sub-systems for Phase-B, namely MEBT and beam diagnostics, have been completed. Keywords: IFMIF, LIPAc, RFQ, Accelerator, Deuteron, Neutron source

The Radio Frequency Quadrupole (RFQ) linac and 1.6 MW RF power system of the Linear IFMIF Prototype Accelerator (LIPAc) facility in the International Fusion Energy Research Center (IFERC) in Rokkasho (Japan) has been installed and conditioned. During the assembly and tuning process, the RFQ cavity was protected with a temporary tent from the potential deterioration of performance caused by dust. The vacuum in the cavity was improved through the 100 °C baking process of the cavity. The high power test of the 175 MHz RF systems up to 200 kW in CW for each of the eight RF chains was performed for checking its stable output reproducibility in Japan, before connecting 9–3/16 inch coaxial transmission lines from the RF chains to the RF input couplers of the cavity. It was confirmed that the eight RF chains provided the balanced RF power to the single RFQ cavity in-phase using a feedback loop and a synchronization system. The peak power in the cavity achieved 150 kW in the pulsed mode, which corresponds approximately to the required electric field to accelerate proton beam. Such RF conditioning process is ongoing to achieve 600 kW approximately required for deuteron beam commissioning planned in 2018.

The correlation between microstructure and mechanical property of ion irradiated 12Cr-6Al ODS ferritic steel was studied. Ion irradiation experiments were performed using 10.5 MeV Fe ions up to the nominal displacement damage of 20 dpa with the damage rate of 1 × 10−4 dpa/s, while the irradiation temperature was 300 °C. Oxide nanoparticles showed stable size distribution and mean size under ion irradiation up to 20 dpa. The irradiation microstructure examined by TEM revealed that the mean size and number densities of irradiation-induced defect clusters increased with the displacement damage. The correlation between irradiation microstructure and radiation hardening was theoretically calculated using the dispersed barrier hardening model. The results showed a good agreement with the experimentally measured hardness data up to irradiation at 5 dpa, while a slight discrepancy was found between theoretical and experimental hardness values under irradiation at 20 dpa. Radiation hardening in 12Cr-6Al ODS ferritic steel was mainly caused by irradiation-induced defect clusters below the irradiation dose of 5 dpa. As the irradiation dose increased toward 20 dpa, an additional influence of the radiation appeared, which was assumed to be induced by α’ phase transformation.

The validation of the Linear IFMIF Prototype Accelerator (LIPAc) is being conducted in Rokkasho Fusion Institute of QST, Aomori, Japan. The beam commissioning of the novel LIPAc RFQ has been progressing significantly, and the acceleration of the world highest current deuteron beam of 125 mA to 5 MeV (1 ms, 1 Hz pulsed beam) was achieved for the 1st time in July 2019. This study is devoted to evaluating the amount of beam loss during the high current acceleration phase by measuring the neutron produced by the interaction of the beam with accelerator components so as to verify the accelerator design. The foil activation method and the 3He neutron probes were utilized. It turned out that there was no significant trace of unexpected beam loss at the high energy section of the RFQ and the Medium Energy Beam Transport (MEBT) section.The measurement using the 3He neutron probes provided an evidence that the beam loss was well controlled in the RFQ cavity as designed. This study concludes that the LIPAc RFQ as well as MEBT is working well as predicted by the design calculation, and its concept is successful.

For the development of the International Fusion Materials Irradiation Facility (IFMIF) aiming at material tests for fusion power plants, the construction of the Linear IFMIF Prototype Accelerator (LIPAc) has been conducted at Rokkasho, Japan under the Broader Approach Agreement. The commissioning of LIPAc has been progressing significantly. The world most powerful RFQ successfully accelerated proton beam of 58 mA, and an important project milestone of the acceleration of deuteron beam to 5 MeV with the beam current of 125 mA in pulse mode was successfully achieved. The result proves the validity of the present RFQ design. The adjustment and tuning of the RF power system and the injector for enabling an operation at maximum performances played an important role in achieving this result. For the next step, the preparation of the high duty cycle operation of RFQ is underway. The installation of the HEBT (High Energy Beam Transport line) and the beam dump accepting 1 MW, CW beam, has been completed and a new beam transport line is under manufacturing. Also the assembly of the Superconducting RF (SRF) linac to accelerate the beam up to 9 MeV started in a clean room in Rokkasho., The 14th International Symposium on Fusion Nuclear Technology

The Linear IFMIF (International Fusion Materials Irradiation Facility) Prototype Accelerator (LIPAc) is a 9 MeV, 125 mA, continuous wave (CW) deuteron accelerator aimed to validate the technology for the IFMIF accelerators. The construction of LIPAc, which is currently the most powerful deuteron accelerator in the world, has been carried out under the Broader Approach (BA) Agreement between EU and Japan, and it is located at Rokkasho (Japan). CIEMAT is one of the five European Institutions that has participated in the design, manufacturing and commissioning/operation of the main accelerator components, among them, the Radio Frequency Power System (RFPS). The RFPS contains all the equipment necessary to generate the required RF power to feed the LIPAc cavities. These cavities demand eighteen RF power chains at 175 MHz being distributed as follows: eight 200 kW tetrode-based chains for the Radiofrequency Quadrupole (RFQ), two 16 kW solid-state chains for the re-buncher cavities, and eight 105 kW tetrode-based chains for the Superconducting RF Linac Half-Wave Resonators. The design of the RFPS main components is presented in this paper, including the tetrode-based chains, the Solid-State Power Amplifier (SSPA) for the re-buncher cavities, the High Voltage Power Supplies (HVPSs) for the final amplifiers anodes and the RF water cooling system. Additionally, the main difficulties encountered during the first months of the RFPS commissioning and operation will be described, together with the applied improvements.

During the Engineering Validation and Engineering Design Activities (EVEDA) phase (2007-2014) of the International Fusion Materials Irradiation Facility (IFMIF), an advanced engineering design of the High Flux Test Module (HFTM) has been developed with the objective to facilitate the controlled irradiation of steel samples in the high flux area directly behind the IFMIF neutron source. The development process addressed included manufacturing techniques, CAD, neutronic, thermal-hydraulic and mechanical analyses complemented by a series of validation activities. Validation included manufacturing of 1:1 parts and mockups, test of prototypes in the FLEX and HELOKA-LP helium loops of KIT for verification of the thermal and mechanical properties, and irradiation of specimen filled capsule prototypes in the BR2 test reactor. The prototyping activities were backed by several R&D studies addressing focused issues like handling of liquid NaK (as filling medium) and insertion of Small Specimen Test Technique (SSTT) specimens into the irradiation capsules. This paper provides an up-todate design description of the HFTM irradiation device, and reports on the achieved performance criteria related to the requirements. Results of the validation activities are accounted for and the most important issues for further development are identified.

The construction of the Linear IFMIF Prototype Accelerator (LIPAc) is in progress in Rokkasho, Japan, and the deuteron beam commissioning of the injector began in July 2015. Due to the huge beam current of 125 mA, a large amount of d-D neutrons are produced in the commissioning. The neutron streaming effect through pipe penetrations and underground pits may dominate the radiation dose at the outside of the accelerator vault during the injector operation. In the present study the effective dose rate expected during the injector commissioning was analyzed by a Monte Carlo calculation and compared with the measured value. For the comparison it is necessary to know the total neutron production yield in the accelerator vault, thus a dedicated neutron production yield monitoring system was developed. The yield obtained was smaller than that previously reported in a literature by a factor of a few and seems to depend on some beam conditions. From the comparison it was proved that the calculation always provides a conservative estimate and the dose rates in places where occupational works can always access and the controlled area boundary are expected to be far less than the legal criteria throughout the injector commissioning.

A neutronics benchmark experiment on copper assembly was performed end 2014–beginning 2015 at the 14-MeV Frascati neutron generator (FNG) of ENEA Frascati with the objective to provide the experimental database required for the validation of the copper nuclear data relevant for ITER design calculations, including the related uncertainties. The paper presents the pre- and post-analysis of the experiment performed using cross-section sensitivity and uncertainty codes, both deterministic (SUSD3D) and Monte Carlo (MCSEN5). Cumulative reaction rates and neutron flux spectra, their sensitivity to the cross sections, as well as the corresponding uncertainties were estimated for different selected detector positions up to ∼58 cm in the copper assembly. This permitted in the pre-analysis phase to optimize the geometry, the detector positions and the choice of activation reactions, and in the post-analysis phase to interpret the results of the measurements and the calculations, to conclude on the quality of the relevant nuclear cross-section data, and to estimate the uncertainties in the calculated nuclear responses and fluxes. Large uncertainties in the calculated reaction rates and neutron spectra of up to 50%, rarely observed at this level in the benchmark analysis using today's nuclear data, were predicted, particularly high for fast reactions. Observed C/E (dis)agreements with values as low as 0.5 partly confirm these predictions. Benchmark results are therefore expected to contribute to the improvement of both cross section as well as covariance data evaluations.

For the development of the International Fusion Materials Irradiation Facility (IFMIF) aiming at material tests for fusion power plants, the construction of the Linear IFMIF Prototype Accelerator (LIPAc) has been conducted at Rokkasho, Japan under the Broader Approach Agreement. The commissioning of LIPAc has been progressing significantly. The world most powerful RFQ successfully accelerated proton beam of 58 mA, and an important project milestone of the acceleration of deuteron beam to 5 MeV with the beam current of 125 mA in pulse mode was successfully achieved. The result proves the validity of the present RFQ design. The adjustment and tuning of the RF power system and the injector for enabling an operation at maximum performances played an important role in achieving this result. For the next step, the preparation of the high duty cycle operation of RFQ is underway. The installation of the HEBT (High Energy Beam Transport line) and the beam dump accepting 1 MW, CW beam, has been completed and a new beam transport line is under manufacturing. Also the assembly of the Superconducting RF (SRF) linac to accelerate the beam up to 9 MeV started in a clean room in Rokkasho.

For the development of the International Fusion Materials Irradiation Facility (IFMIF) aiming at material tests for fusion power plants, the construction of the Linear IFMIF Prototype Accelerator (LIPAc) has been conducted at Rokkasho, Japan under the Broader Approach Agreement. The commissioning of LIPAc has been progressing significantly. The world most powerful RFQ successfully accelerated proton beam of 58 mA, and an important project milestone of the acceleration of deuteron beam to 5 MeV with the beam current of 125 mA in pulse mode was successfully achieved. The result proves the validity of the present RFQ design. The adjustment and tuning of the RF power system and the injector for enabling an operation at maximum performances played an important role in achieving this result. For the next step, the preparation of the high duty cycle operation of RFQ is underway. The installation of the HEBT (High Energy Beam Transport line) and the beam dump accepting 1 MW, CW beam, has been completed and a new beam transport line is under manufacturing. Also the assembly of the Superconducting RF (SRF) linac to accelerate the beam up to 9 MeV started in a clean room in Rokkasho.

The IFMIF Test Cell (TC) design was developed and optimized in the EVEDA phase, and finally the reference TC design was proposed. The present study is devoted to further investigations of open issues on the reference TC design. In order to examine the neutron streaming effect caused by pipe penetrations and gaps around removable shielding plugs, a new geometry model for neutronic analyses has been prepared directly from engineering CAD data by utilizing the McCad conversion software. All removable shielding plugs are separately described in the model and a detailed description of pipes was incorporated into the model. The calculation result suggests that the streaming effect is mitigated if the pipe penetration is designed appropriately, while the gaps around the shielding plugs above the TC have large impact on the radiation dose in the access cell. The concept of the reference TC design has been basically validated from the neutronics point of view, although the streaming effect should be compensated by the shielding capability of the test cell cover plate so that occupational workers can access to the access cell during operation.

The R2Smesh (“Rigorous 2-step”) approach, developed by KIT for the determination of shut down dose rate distributions on high resolution mesh grids, can be utilized to calculate photon radiation dose fields around activated components which are moved from the irradiation site in ITER to some external location. In this work, the R2Smesh approach has been applied to dose rate analyses of various ITER in-vessel components of high complexity: A divertor cassette, four first wall modules, a generic diagnostic equatorial port plug and two test blanket modules. The considered components were first irradiated in ITER, and then moved to the transfer cask together with the associated decay gamma source distribution for the calculation of high resolution radiation dose fields in and around the transfer cask. The R2Smesh approach was shown to be a versatile tool for performing such analyses.

A neutron source for material and component tests is an essential tool for the DEMO reactor development. An accelerator-based neutron source such as IFMIF is regarded as the most promising one in J...

The IFMIF Tritium Release Test Module (TRTM) is projected to measure online the tritium release from breeder ceramics and beryllium pebble beds under high energy neutron irradiation. Tritium produced in the pebble bed of TRTM is swept out continuously by a purge gas flow, but can also permeate into the module's metal structures, and can be lost by permeation to the environment. According analyses on the tritium inventory are performed to support IFMIF plant safety studies, and to support the experiment planning. This paper describes the necessary elements for calculation of the tritium transport in the Tritium Release Test Module as follows: (i) applied equations for the tritium balance, (ii) material data from literature and (iii) the topological models and the computation of the five different cases; namely release of tritium from the breeder solid material into the purge gas, loss of tritium over the capsule wall, rig hull, container wall and purge gas return line in detail. The problem of tritium transport in the TRTM has been studied and analyzed by the Tritium Migration Analysis Program (TMAP) and the adapted fusion-devoted Tritium Permeation Code (FUS-TPC). TMAP has been developed at INEEL and now exists in Version 7. FUS-TPC Code was written in MATLAB with the original purpose to study the tritium transport in Helium Cooled Lead Lithium (HCLL) blanket and in a later version the Helium Cooled Pebble Bed (HCPB) blanket by [6] (Franza, 2012). This code has been further modified to be applicable to the TRTM. Results from the computations for the five computational cases concerning safety and experiment analyses are presented.

The International Fusion Materials Irradiation Facility (IFMIF) is designated to generate a materials irradiation database for the future fusion reactors. The Test Cell (TC) accommodates the Test Modules and the lithium target assembly. Due to the nuclear heat generation, all the Test Modules inside the TC will be actively cooled. Other components like supporting structures, pipelines, cables etc., will be passively cooled by natural convection. The heat will be removed from the steel liners surrounding the TC by active water cooling. This paper concerns the thermo-hydraulic simulations of the Test Cell using Ansys-CFX. The current simulation model includes the natural convection inside the TC, several forced convective water flows in the pipelines attached on the steel liners and the helium-cooled HFTM (High Flux Test Module). The simulations provide the only means for validating the design before the construction and operation.

The latest design updates of the IFMIF-EVEDA reference test cell (TC) are described with emphasis on the following key components: active cooling pipes for concrete biological shielding walls and stainless steel liner, TC gas leak tight boundary, and piping and cabling inside TC and between TC and the access cell (AC). Water cooling is adopted for concrete shielding walls and the liner. Buried pipes are selected for active cooling of the TC surrounding shielding walls; directly welded pipes on the liner are used to remove nuclear heat of the liner. Technical features and layout of the cooling pipes are preliminary defined. The TC vacuum boundary, which includes the TC liner, an independent TC cover plate, a rubber based sealing gasket, and welding seams between interface shielding plugs and TC liner, is described. Engineering design of the piping and cabling plugs as well as the arrangement of pipes and cables under the TC covering plate and the AC floor are updated. Pipes and cable tunnels inside the shielding plugs are arranged with several bends for minimizing neutron streaming from inside to outside of the TC. Pipes, cables, and the corresponding penetrations between the TC and the AC are carefully arranged for convenient access and maintenances.

The IFMIF test cell (TC) design has been further developed and optimized in the EVEDA phase, and finally the reference TC design has been proposed. In order to carry out the detailed neutronic analysis for the reference TC design, a very detailed geometrical model for Monte Carlo neutronic calculations has been prepared directly from engineering CAD data by utilizing the McCad conversion software developed at KIT. The geometrical model includes the detailed descriptions of the lithium target system proposed by Japan, all test modules based on the EVEDA phase design, and the 3-dimesional arrangement of the biological shielding. The Monte Carlo code McDeLicious, which is an enhancement to MCNP5, has been utilized in order to adequately simulate the neutron and photon productions from the 6,7Li(d,xn) reactions in the lithium target. The present analysis is focusing on the nuclear heating distribution inside the biological shielding, the nuclear property of the TC liner, and the biological dose distribution around TC during operation. Some countermeasures for reducing the He production in the liner are discussed.

This paper summarizes the benchmark analyses performed in a joint effort of ENEA (Italy), JAEA (Japan), KIT (Germany), and the University of Wisconsin (USA) on a computational ITER benchmark and a series of 14 MeV neutron benchmark experiments. The computational benchmark revealed a modest increase of the neutron flux levels in the deep penetration regions and a substantial increase of the gas production in steel components. The comparison to experimental results showed good agreement with no substantial differences between FENDL-3.0 and FENDL-2.1 for most of the responses. In general, FENDL-3 shows an improved performance for fusion neutronics applications. © 2014 Elsevier Inc.

This work presents neutronic analyses to support the design of the test facility of the International Fusion Materials Irradiation Facility (IFMIF) in the framework of the Broader Approach activities. In order to evaluate the necessary biological shielding thickness and the reliability of remote handling tools for activated components inside the Test Cell, a detailed activation analysis has been carried out to obtain a detailed residual dose map resulting from the entire High Flux Test Module and Test Cell by utilizing the McDeLicious-11 Monte Carlo code and the mesh-tally based rigorous 2-Step approach (R2Smesh) developed at KIT. The absorbed dose rate expected at the working place of remote handling tools inside the Test Cell is approximately 100 Gy/h. A wall thickness of 150 cm for heavy concrete can be used as the design basis for hot cells in the test facility.

*Recently IAEA has been conducting a coordinated research project to update the FENDL-2.1 nuclear data library to FENDL-3. In the present study, FENDL-3, Starter Library, Release 4 (FENDL-3/SLIB4) has been extensively tested through analysis of many fusion relevant benchmark problems. FENDL-3/SLIB4 gives better results for the FNG ITER shielding benchmark and the tungsten benchmark experiments than the previous FENDL-2.1. As for the shielding benchmark in the neutron energy range above 20 MeV, the TIARA transmission experiments through iron and concrete using p-Li quasi-monoenergetic neutron source have been analyzed. FENDL-3/SLIB4 provides satisfactory results for the TIARA shielding benchmark through iron. For concrete, however, some discrepancy was found. The present analysis suggests importance of 16 O data in