Study of the EU-DEMO WCLL Breeding Blanket Primary Cooling Circuits Thermal-Hydraulic Performances during Transients Belonging to LOFA Category

Abstract

The Breeding Blanket (BB) is one of the key components of the European Demonstration (EU-DEMO) fusion reactor. Its main subsystems, the Breeder Zone (BZ) and the First Wall (FW), are cooled by two independent cooling circuits, called Primary Heat Transfer Systems (PHTS). Evaluating the BB PHTS performances in anticipated transient and accident conditions is a relevant issue for the design of these cooling systems. Within the framework of the EUROfusion Work Package Breeding Blanket, it was performed a thermal-hydraulic analysis of the PHTS during transient conditions belonging to the category of “Decrease in Coolant System Flow Rate”, by using Reactor Excursion Leak Analysis Program (RELAP5) Mod3.3. The BB, the PHTS circuits, the BZ Once Through Steam Generators and the FW Heat Exchangers were included in the study. Selected transients consist in partial and complete Loss of Flow Accident (LOFA) involving either the BZ or the FW PHTS Main Coolant Pumps (MCPs). The influence of the loss of off-site power, combined with the accident occurrence, was also investigated. The transient analysis was performed with the aim of design improvement. The current practice of a standard Pressurized Water Reactor (PWR) was adopted to propose and study actuation logics related to each accidental scenario. The appropriateness of the current PHTS design was demonstrated by simulation outcomes.

Analysis of EU-DEMO WCLL Power Conversion System in Two Relevant Balance of Plant Configurations: Direct Coupling with Auxiliary Boiler and Indirect Coupling

“…Although these minor differences, the operational parameters of the BB PHTSs remain the same in both configurations. Those parameters, together with operational features of the DIV and VV PHTSs, are summarized in Table 1 [6,[16][17][18] and constitute the boundary conditions of the present study. It is worth emphasizing that such values represent operative parameters in pulse mode.…”

Transient Analysis of a Locked Rotor/Shaft Seizure Accident Involving the Eu-Demo Wcll Breeding Blanket Primary Cooling Circuits

“…For this reason, the approximation done in the model was considered acceptable for preliminary assessment of the blanket behavior. More details about the BB modeling choices are available in [10,11]. The schematic view of the model related to one blanket sector is shown in Fig.…”

“…Within the framework of EUROfusion Work Package Breeding Blanket, a simulation activity was carried out by Department of Astronautical, Electrical and Energy Engineering (DIAEE) of Sapienza University of Rome in collaboration with ENEA research center of Brasimone. The "Decrease in Coolant System Flow Rate" category of accidents was selected to be investigated [10,11]. A complete model of the BB and PHTS circuits was prepared.…”

“…Transient calculations were performed with RELAP5/Mod3.3 best-estimate system Thermal-Hydraulic (TH) code [12]. A modified version of the code was developed at DIAEE [10,11], where modeling capabilities of fusion reactors were enhanced.…”

Evaluation of the thermal-hydraulic performances of a once-through steam generator in nuclear fusion applications

“…To reach this goal, a full model of the component was prepared by using a modified version of RELAP5/MOD3.3 system code. This new extended version was developed at DIAEE, in collaboration with ENEA, to enhance the code capability in simulating fusion reactors, [6]. It is actually considered the reference code version to carry out the future simulation activity involving DEMO reactor.…”