Recent Publications

Measurements and analysis of short-term activation of ITER samples exposed in irradiation-end during DT operations at JET

Ewa Łaszyńska, Jakub Piotr Włodarczyk, Sabahattin Akbas, Barbara Bieńkowska, Zamir Ghani, Callum Grove, Xavier L Litaudon, Lee William Packer, Chantal Shand, Rosaria Villari, et al.

United Kingdom Atomic Energy Authority, Institute of Plasma Physics and Laser Microfusion, AGH University of Krakow, CEA, ENEA

Short-lived activation products in fusion materials are critical for assessing radiological safety and maintenance planning in future fusion reactors like ITER. These products influence shutdown dose rates, impact maintenance procedures, and provide essential validation for nuclear data and activation models in the short term. Understanding their formation and decay behavior under deuterium-tritium (DT) plasma conditions allows for more accurate predictions of material performance and safety constraints. This study analyzes the short-term activation of ITER materials exposed at the KN2 6U irradiation end in the JET (Joint European Torus) tokamak during the DTE2 and DTE3 campaigns. CuCrZr, IWS A286, and SS316L(N) samples were activated during DTE2, while tungsten monoblock, a key ITER divertor material, was irradiated during DTE3. Activated samples were promptly transported via a pneumatic post system for gamma spectrometry measurements using UKAEA’s 190% relative efficiency HPGe (High-Purity Germanium) detector. The efficiency calibration was performed with the MCNP 6.1 code, employing an MCNP detector model validated by a certified multi-gamma calibration source. The experimental data were compared with FISPACT-II activation calculations, enabling the determination of calculation-to-experiment (C/E) ratios. This study provides key validation data for nuclear activation models and improves the accuracy of computational predictions for material behavior in fusion reactors.

Instrumentation integration and dynamic force reconstruction in the TBM attachment

Eduardo Rodríguez-López, David Alonso, Victor Domínguez, Luis Maqueda, Magdalena Roca, Fernando Rueda, Pablo Ruiz, Alejandro Vázquez, Álvaro Yáñez, Joelle Vallory, et al.

Esteyco Mechanics, Fusion for Energy

Effect of neutron irradiation swelling on monoblock fracture in the DEMO reactor

M. Bruno, G. Cricrì, N. Mantel, J.H. You, R. Citarella

University of Napoli Federico II, United Kingdom Atomic Energy Authority (UKAEA), Max Planck Institute for Plasma Physics, University of Salerno

Measurement of 80% Lithium–20% Boron Composite Material Electrical Resistivity, Thermal Expansion, and Thermal Diffusivity at Elevated Temperatures

Rostislav Selivanov, Dmitry Shuvalov, Ivan Sorokin, Andrey Chernushich, Valery Zhaharov, Olga Volkova, Alexey Rudenko, Stepan Krat

National Research Nuclear University MEPhI, Russian Academy of Sciences, Institute of High Temperature Electrochemistry of the Ural Branch of Russian Academy of Sciences

European test blanket modules: An overview of fabrication technologies development and EUROFER97 steel supply

Milan Zmitko, Yves Poitevin, Laurent Forest, Antonella Li Puma, Rémi Boullon, Jérôme Tosi, Denis Sornin, Philippe Emonot, Emmanuel Rigal, Laurence Cogneau, et al.

CEA, Université Paris-Saclay, Univ. Grenoble Alpes, APAVE Exploitation France, ALSYMEX

Preliminary nuclear and thermal analysis of a dual-coolant lead-lithium blanket concept for the Helios fusion power plant

S. Pasmann, A. van Riel, U. Khera, P.K. Romano, A. Koen, M. Donovan, C.P.S. Swanson, D.A. Gates

Thea Energy, Inc.

Development and validation of a fully integrated RMC R2S framework for shutdown dose rate calculation

Kok Yue Chan, Hao Luo, Zhe Chuan Tan, Yuanhao Gou, Kan Wang

Tsinghua University, Singapore Nuclear Research and Safety Initiative

Impact of neutronics analyses on the lower port configuration of 2024 Volumetric Neutron Source

Aljaž Čufar, Christian Bachmann, Jean Boscary, Paolo Gallina, Curt Gliss, Primož Lesjak, Domenico Marzullo, Pavel Pereslavtsev, Sebastien Renard, Pietro Vinoni

EUROfusion Consortium, Consorzio CREATE, University of Trieste, Jožef Stefan Institute, Max–Planck-Institut für Plasmaphysik

Neutronics, radiolysis and OSCAR-Fusion analysis for the design of a flow loop for Activated Corrosion Products studies

S. Noce, G. Bailey, L. Butt, Y.-L. Chiu, A. Colangeli, F. Dacquait, M. Damiano, D. Flammini, N. Fonnesu, M.R. Gilbert, et al.

ENEA, UKAEA, The University of Birmingham, CEA, University of Rome “Tor Vergata”

Benchmarking of the FLUKA Monte Carlo code against the SINBAD FNG dose experiment for shutdown dose rates in D–T fusion applications

Tommaso Lorenzon, Davide Bozzato, Robert Froeschl, Lewis MacFarlane

European Organization for Nuclear Research (CERN), Universitat Politècnica de Catalunya (UPC), TÜV SÜD UK

DEM study on the effect of contact radius ratio on the crushing behavior of Li₄SiO₄ pebbles

Du-Min Kuang, Jia Su, Zhao-Rong Chen, Xing Sun, Ikechukwu ogwu

Xiangtan University, China National Nuclear Power Rich Energy Renewables Co. Ltd. (Hunan), Hunan Institute of Engineering

Neutron-source fidelity for laser-driven D--D lithium-blanket tritium-breeding tests

Chengqi-Zhang, Yang He, Mamat Ali Bake, Baisong-Xie

Compact deuterium--deuterium (D--D) neutron sources can provide controllable irradiation fields for lithium-blanket studies, although their broad joint energy and angle distributions differ from the conventional $2.45$~MeV isotropic representation. We couple particle-in-cell (PIC) simulations of target-normal-sheath-accelerated deuterons with a thick-target $D(d,n)^{3}$He source model and Monte Carlo neutron transport. For natural lithium, the seven two-dimensional sources change tritium production per source neutron by $-2.5\%$ to $+54.1\%$ relative to the ideal source. The matched three-dimensional calculation gives an increase of $43.5\%$ and lowers the corresponding ratio from $1.5406$ to $1.4350$. Source substitutions show that the difference is predominantly spectral, since the real spectrum alone gives a factor of $1.4199$, while using the real neutron emission directions in place of isotropic emission adds only a further factor of $1.0106$ in the three-dimensional case. The real spectrum lowers the $^{6}$Li contribution by $6.9\%$, but the accessible $^{7}$Li$(n,Xt)$ response exceeds this loss. Enrichment to $90\%$ $^{6}$Li keeps the total change within $\pm1.5\%$. In the matched three-dimensional converter and blanket calculation, direct $D(d,p)$T production is $0.8458$ tritons per source neutron and accounts for $98.1\%$ and $86.9\%$ of the combined production for natural and enriched lithium, respectively. High-density polyethylene moderation raises tritium production by about one order of magnitude but first weakens and then reverses the increase in blanket tritium production. The analysis quantifies source-model effects in compact breeding tests.

The research plan for the ITER TBM program

Luciano M. Giancarli, Mu-Young Ahn, Paritosh Chaudhuri, Seungyon Cho, Takanori Hirose, Paul Humrickhouse, Yoshinori Kawamura, Francesca Fantini, Italo Ricapito, Rossella Rotella, et al.

ITER Organization, QST, KFE, Fusion for Energy, Institute for Plasma Research

Adapting the D1S methodology for high-fluence fusion environments with tungsten: application to ITER

Alberto Bittesnich, Marco Fabbri, Patrick Sauvan, Antonio Jesus Lopez-Revelles, Aljaž Kolšek, Neil Taylor, Alfredo Portone

Fusion For Energy, UNED - Universidad Nacional de Educacion a Distancia, ATG Science & Engineering, SL, Universitat Politecnica de Catalunya

Deuterium release from lithium-lead droplets formed under 2.0 mm nozzle flow

Fumito Okino, Yukinori Hamaji, Juro Yagi, Teruya Tanaka

Kyoto University, National Institute for Fusion Science

Activation analysis and waste assessment of the electron cyclotron in EU-DEMO

S. Akbas, B. Bienkowska, E. Laszynska, J. Wlodarczyk, S. Rosanvallon, J. Elbez-Uzan

Institute of Plasma Physics and Laser Microfusion, EUROfusion, CEA, AGH University of Krakow

Preliminary engineering analysis for CN HCCB TBM regarding ITER new baseline scenario

Xinghua Wu, Shen Qu, Ruyan Li, Hongxiang Zhang, Qixiang Cao, Fengchao Zhao, Long Zhang, Xiaoyu Wang

Southwestern Institute of Physics, China Fusion Energy Co. Ltd

Among the various breeding blanket concepts proposed for DEMO reactor design by different countries, China has ultimately determined to develop and test the Helium-Cooled Ceramic Breeder Test Blanket Module (HCCB TBM) in ITER, in alignment with its national strategy for the development of magnetic confinement fusion energy. During the preliminary design phase, the CN HCCB TBM team implemented several design updates to improve its engineering performance and manufacturing feasibility, however, in response to certain engineering and technical challenges, a new ITER baseline has been under development since early February 2023. This new baseline proposed a revised ITER operation strategy aimed at initiating the nuclear phase as early as possible while reducing selected operational parameters in the initial stages. In accordance with the ITER 2024 new baseline scenario, further design optimization and engineering analysis have been conducted for the CN HCCB TBM. Thermal-hydraulic analysis results demonstrate that, the maximum operating temperatures of structural and functional materials were significantly reduced under the 2024 baseline scenario, especially for the tritium breeder Li 4 SiO 4 pebble bed, whose temperature was decreased by 20.6%. By installing electric heaters within the tritium breeder zone, the peak temperature of Li 4 SiO 4 can be increased to 821 °C, and the average temperature raised o 604 °C, which essentially satisfied the temperature requirements for tritium release. Based on the calculated temperature distributions under three operating conditions, a system-level transient tritium transport analysis was further performed. The results reveal that installing electric heaters exclusively in the tritium breeder region is sufficient to meet tritium balance requirements, eliminating the need for additional electric heaters in the neutron multiplier region. Preliminary structural analysis was also carried out, and the results indicated that the linearized stresses remain well below the allowable limits of the structural material, thereby ensuring the integrity of the overall structure.

Calibration strategy and uncertainty analysis of the ITER neutron activation system for deuterium–deuterium plasma operation *

Giovanni Mariano, Andrei Kovalev, Mark Fortuna, Silvia Di Sarra, Vitaly Krasilnikov, An YoungHwa, Bruno Coriton

ITER Organization, Jožef Stefan Institute, Korea Institute of Fusion Energy

The International Thermonuclear Experimental Reactor (ITER) neutron activation system (NAS) is an essential diagnostic system designed to measure the total neutron yield and the first-wall fluence in the ITER Tokamak. NAS principle is based on the neutron activation of small sample materials placed in the vicinity of the plasma using pneumatic transfer lines. The induced activity in the samples is subsequently measured using a gamma-ray counting station, enabling reconstruction of the total neutron yield. Accurate neutron transport modelling of both the NAS apparatus and the tokamak is essential for reliable measurements. This study systematically quantifies the primary sources of uncertainty in the NAS neutronic model, focusing on the geometric modelling of the NAS irradiation ends and tokamak environment, as well as uncertainties in nuclear data. Results indicate that the NAS can achieve a measurement accuracy of approximately 13% in deuterium–deuterium (DD) plasmas, with the largest uncertainty attributed to the detailed geometry of the diagnostic first-wall (DFW). To address this, in-situ calibration is paramount to identify unforeseen measurement errors and to mitigate the uncertainties in computational models. Utilizing a well-characterized neutron generator for NAS calibration could reduce the neutron yield measurement errors below 8%. These findings underscore the importance of precise modelling and calibration procedures for accurate neutron measurements during ITER’s start of research operation (SRO).

Forward Monte Carlo modeling of HL-3 D-D neutron spectra with fitted differential cross sections

Y.F. Xie, X.J. Chen, J.J. Qian, Y.W. Su, X.L. Chen, J. Zhang

Sichuan University, Southwestern Institute of Physics

Tritium production and processing systems for ST-E1

E. Yildirim, J. Naish, J. Trueba, S. Levine, A. Kumar, V.B. Gohani, M.K.E. Mohamed, A. Vorobev, L. Yang, P.C. Simon, et al.

Tokamak Energy Ltd, Savannah River National Laboratory (SRNL), Oak Ridge National Laboratory (ORNL), Idaho National Laboratory (INL), The Pennsylvania State University

An integrated tritium fuel-cycle architecture has been developed for ST-E1, a low-aspect-ratio, high-power fusion power plant. The approach couples a helium-cooled liquid-lithium breeder blanket with a dedicated circulation loop providing tritium extraction, heat removal, and inventory control within a unified system boundary. Downstream of the blanket, the tritium processing system comprises of extraction, purification, isotope separation, and storage subsystems sized to accommodate the plant’s dynamic tritium production and consumption rates. Inventory modelling is used to assess candidate extraction schemes, evaluate tritium residence and holdup, and quantify sensitivities associated with protium control and intermediate inventories. The integrated assessment indicates that the combined blanket-processing architecture can satisfy startup and steady-state tritium requirements within credible operating margins, with a low overall inventory and acceptable doubling time. The results identify tritium extraction sensitivity and fuelling efficiency as the dominant drivers of inventory performance, rather than marginal improvements in breeding ratio. Overall, the analysis demonstrates the feasibility of a self-consistent fuel cycle for ST-E1 and highlights the critical dependencies between blanket inventory management, processing throughput, and overall plant performance.