Identification of accident sequences for the DEMO plant

Pinna, T.; Carloni, D.; Carpignano, Andrea; Ciattaglia, S.; Johnston, Jane; Porfiri, M.T.; Savoldi, Laura; Taylor, Neill; Sobrero, G.; Uggenti, Anna Chiara; Vaišnoras, Mindaugas; Zanino, Roberto

doi:10.1016/j.fusengdes.2017.02.026

Cited by 33 publications

(8 citation statements)

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“…A set of postulated initiating events (PIEs) have been identified for the DEMO in [21], including for divertor system in/ex-vacuum vessel (VV) Loss-of-Coolant Accidents and Loss-of-Flow Accidents. The present work investigates the consequences of an in-VV LOCA originating from a divertor cassette loop breach and the additional impact in terms of VV pressurization when considering the contextual failure of both the cassette and PFU.…”

Section: Accident Specification For the Considered Casesmentioning

confidence: 99%

DEMO Divertor Cassette and Plasma facing Unit in Vessel Loss-of-Coolant Accident

Dongiovanni¹,

D’Onorio

Caruso

et al. 2022

Energies

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As part of the pre-conceptual design activities for the European DEMOnstration plant, a carefully selected set of safety analyses have been performed to assess plant integrated performance and the capability to achieve expected targets while keeping it in a safe operation domain. The DEMO divertor is the in-vessel component in charge of exhausting the major part of the plasma ions’ thermal power in a region far from the plasma core to control plasma pollution. The divertor system accomplishes this goal by means of assemblies of cassette and target plasma facing units modules, respectively cooled with two independentheat-transfer systems. A deterministic assessment of a divertor in-vessel Loss-of-Coolant Accident is here considered. Both Design Basis Accident case simulating the rupture of an in-vessel pipe for the divertor cassette cooling loop, and a Design Extension Conditions accident case considering the additional rupture of an independent divertor target cooling loop are assessed. The plant response to such accidents is investigated, a comparison of the transient evolution in the two cases is provided, and design robustness with respect to safety objectives is discussed.

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Section: Accident Specification For the Considered Casesmentioning

confidence: 99%

DEMO Divertor Cassette and Plasma facing Unit in Vessel Loss-of-Coolant Accident

Dongiovanni¹,

D’Onorio

Caruso

et al. 2022

Energies

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“…Among the possible accidents, the first scenario that has been considered is the In-vessel LOCA [2]. Initially, the postulated initiating events (PIE), which can cause this scenario, have been evaluated: LFV1 (Large First Wall rupture) [3] and LDV1 (In-Vessel LOCA caused by a divertor cassette large rupture) [3]. In this work, it has been selected the LDV1 case; in particular, it has been performed the simulation of a break of the divertor primary cooling circuit, assuming a rupture of the tube apparatus inside the divertor component itself [4].…”

Section: Introductionmentioning

confidence: 99%

Preliminary thermal-hydraulic deterministic safety analysis of an in-vessel LOCA for the DTT facility

Grippo,

Bersano,

Mascari

2024

J. Phys.: Conf. Ser.

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The DTT (Divertor Tokamak Test) facility is a new experimental tokamak under development by an Italian consortium in cooperation with several high-standard European laboratories. The ENEA division FSN-SICNUC is involved in the project for carrying out deterministic safety analysis of postulated accidents. In the first year of activity, it has been analyzed an In-Vessel LOCA (IVLOCA) scenario. The IVLOCA scenario selected is caused by a break in the divertor’s cassette cooling tubes with the consequent release of coolant inside the Vacuum Vessel (VV). The best estimate thermal-hydraulic system code TRACE, developed by USNRC, was selected to conduct the preliminary thermal-hydraulic analysis of this accident. DTT is currently under design, so not all the data are frozen. Therefore, based on some engineering assumptions and scaling considerations from similar facilities, the nodalization of DTT VV was developed using the three-dimensional TRACE component “VESSEL”. Then, a sensitivity analysis was carried out to simulate the break and the consequent water injection in the VV. This was done to compare the system behavior and test different nodalization approaches. Subsequently, the data of the DTT divertor cooling system were used to run additional simulations. The results allow to compare different nodalization approaches and to have a preliminary estimate of the pressure peak and temperature behavior in the VV for an IVLOCA. Finally, a first uncertainty analysis was carried out using the DAKOTA toolkit, coupled with TRACE code in SNAP. Two uncertain input parameters were selected: the rupture area of a cooling divertor tube and the temperature of the divertor coolant. The uncertainty analysis allows having a wider spectrum of system behavior and a preliminary insight on the dispersion of the VV pressure, selected as figure of merit. This paper aims to show the results of this preliminary analysis, characterizing the phenomena that occurred during the selected transient.

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“…Safety studies are performed in the frame of the EUROfusion Safety and Environment (SAE) work package to support design improvement and evaluate the thermal-hydraulic behavior of confinement building environments during accident conditions in addition to source term mobilization. A functional failure modes and effects analysis (FFMEA) [9] classified both in-vessel and ex-vessel LOCA among the most representative events in terms of challenging conditions for plant safety since they could cause substantial damage to structures and principal components. In particular, the large enthalpy stored in the breeding blanket (BB) coolant water could threaten confinement barriers' structural integrity, causing the release of radioactive substances into the environment.…”

Section: Introductionmentioning

confidence: 99%

Development of a Thermal-Hydraulic Model for the EU-DEMO Tokamak Building and LOCA Simulation

et al. 2023

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The EU-DEMO must demonstrate the possibility of generating electricity through nuclear fusion reactions. Moreover, it must denote the necessary technologies to control a powerful plasma with adequate availability and to meet the safety requirements for plant licensing. However, the extensive radioactive materials inventory, the complexity of the plant, and the presence of massive energy sources require a rigorous safety approach to fully realize fusion power’s environmental advantages. The Tokamak building barrier design must address two main issues: radioactive mass transport hazards and energy-related or pressure/vacuum hazards. Safety studies are performed in the frame of the EUROfusion Safety And Environment (SAE) work package to support design improvement and evaluate the thermal-hydraulic behavior of confinement building environments during accident conditions in addition to source term mobilization. This paper focuses on developing a thermal-hydraulic model of the EU-DEMO Tokamak building. A preliminary model of the heat ventilation and air conditioning system and vent detritiation system is developed. A loss-of-coolant accident is studied by investigating the Tokamak building pressurization, source term mobilization, and release. Different nodalizations were compared, highlighting their effects on source term estimation. Results suggest that the building design should be improved to maintain the pressure below safety limits; some mitigative systems are preliminarily investigated for this purpose.

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Identification of accident sequences for the DEMO plant

Cited by 33 publications

References 0 publications

DEMO Divertor Cassette and Plasma facing Unit in Vessel Loss-of-Coolant Accident

DEMO Divertor Cassette and Plasma facing Unit in Vessel Loss-of-Coolant Accident

Preliminary thermal-hydraulic deterministic safety analysis of an in-vessel LOCA for the DTT facility

Development of a Thermal-Hydraulic Model for the EU-DEMO Tokamak Building and LOCA Simulation

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