Dynamic analysis and control design for the gas distribution and storage system of the tritium fuel cycle in EU-DEMO

Jul 16, 2026

Control strategies for the Direct Internal Recycling Loop (DIRL) of the Tritium Fuel Cycle (TFC) are developed to support fusion reactor fueling in EU-DEMO. A control-oriented dynamic model is built to capture DIRL behavior, including interactions among the torus reactor, buffer and fuel units, and recirculation streams. Controllability, stability, and input–output interactions are analyzed from a gas-distribution perspective. Three GDS strategies are evaluated using MIMO control, extended-input redesigned decentralized SISO control, and an extended-input MIMO approach to meet protium dilution objectives while managing pressure and fuelling ratio constraints.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages33

Reading Time1 h 23 min

Introduction

Control-oriented dynamic modeling of DIRL

Controllability, stability, and input–output interaction analysis

Control strategies for GDS in EU-DEMO

Control objectives and evaluation criteria

Graphical Abstract Dynamic analysis and control design for the gas distribution and storage system of the tritium fuel cycle in EU-DEMO C.A. Gómez-Pérez, M. van Berkel, L. Özkan arXiv :2607 . 10866v1 [ ee ss . SY] 12 Jul 2026 Highlights Dynamic analysis and control design for the gas distribution and storage system of the tritium fuel cycle in EU-DEMO C.A. Gómez-Pérez, M. van Berkel, L. Özkan • A control-oriented dynamic model for direct inner circulation loops is proposed, supporting both dynamic analysis and control design. • Direct recirculation of exhaust gases reduces tritium draw from storage, while steady-state protium composition at the fusion reactor inlet increases with the separation yield of the metal foil and vacuum pump unit. • Relative Gain Array (RGA) analysis is used to identify the preferred input-output pair structure selection for the direct inner circulation loop. • Based on RGA analysis, an actuator placement strategy is proposed that reduces input–output interactions and improves decentralised SISO control performance. • An LQR MIMO controller is also designed achieving good closed-loop performance; however, protium build-up cannot be avoided with a limited input set. • An adjusted LQR MIMO controller with an extended input set is proposed to address the protium dilution objective and overcome protium build-up Dynamic analysis and control design for the gas distribution and storage system of the tritium fuel cycle in EU-DEMO C.A. Gómez-Péreza,b,∗, M. van Berkela,b , L. Özkana a Eindhoven University of Technology, Department of Electrical Engineering, Control Systems, De Zaale, Eindhoven, 5612 AE, Netherlands b Dutch Institute For Fundamental Energy Research, De Zaale 20, Eindhoven, 5612 AJ, Netherlands Abstract This work is concerned with the development of control strategies for the Direct Internal Recycling Loop (DIRL) system, which is an essential part of the Tritium Fuel Cycle (TFC) for the fueling of fusion reactors. As a first step, a control-oriented model is developed that describes dynamic behavior of DIRL with interactions between the torus reactor, buffer and fuel units, and recirculation streams. This model is used to evaluate the controllability, stability of the DIRL, and interactions between input and output variables. Moreover, the direct recycling of isotopes from the exhaust gases is discussed from a control perspective. It is observed that Gas Distribution and Storage (GDS) within the DIRL is associated with significant control challenges due to input–output interactions and competing process objectives. Three control strategies are developed and evaluated for the GDS of the European Demonstration fusion power plant (EU-DEMO): a Multiple Input Multiple Output (MIMO) control scheme, a redesigned GDS configuration with extended input variables enabling decentralised Single Input Single Output (SISO) control, and an extended-input MIMO control scheme addressing protium dilution. All strategies are assessed against three control objectives: maintaining GDS pressure around a prescribed set-point to ensure process safety; regulating the tritium–deuterium fuelling ratio for optimal reactor ∗ Corresponding author Email addresses: [c.a.gomez.perez@tue.nl](c.a.gomez.perez@tue.nl) (C.A. Gómez-Pérez), [M.vanBerkel@differ.nl](M.vanBerkel@differ.nl) (M. van Berkel), [l.ozkan@tue.nl](l.ozkan@tue.nl) (L. Özkan) operation; and managing protium concentration to prevent fuelling dilution. Keywords: Tritium Fuel Cycle, DEMO, Direct Inner Recirculation Loop, Hydrogen gas dynamics, Multivariable control, Optimal actuator selection Nomenclature Symbol Description Roman symbols N Mol n number of elements n˙ Mol flow t time V Volume P Pressure T Temperature R Ideal gas constant F Volumetric flow x Mol fraction C Mol concentration x State variable vector u Input variable vector y Output variable vector Cd Valve coefficient A Val

FAQs

What system does the document focus on within the Tritium Fuel Cycle?

It focuses on the Direct Internal Recycling Loop (DIRL), a key component of the Tritium Fuel Cycle used for fueling fusion reactors in EU-DEMO.

How is the gas distribution and storage (GDS) part of DIRL approached for control design?

A control-oriented dynamic model is used to analyze interactions between inputs and outputs, assess controllability and stability, and evaluate how GDS creates control challenges due to coupled objectives.

What control strategies are developed and what are they intended to achieve?

Three GDS strategies are evaluated: a MIMO control scheme, a redesigned GDS with extended inputs enabling decentralized SISO control, and an extended-input MIMO scheme aimed at protium dilution and mitigating protium build-up with limited input sets.

Jul 16, 2026

Upload by Genevieve