Transient analysis of an FHR coupled to a helium Brayton power cycle

Journal Article · Sat Aug 01 00:00:00 EDT 2015 · Progress in Nuclear Energy

DOI:https://doi.org/10.1016/j.pnucene.2015.02.015· OSTI ID:1188621

Chen, Minghui ^[1]; Kim, In Hun ^[1]; Sun, Xiaodong ^[1]; Christensen, Richard ^[1]; Utgikar, Vivek ^[2]; Sabharwall, Piyush ^[3]

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1. The Ohio State Univ., Columbus, OH (United States). Nuclear Engineering Program
2. Univ. of Idaho, Idaho Falls, ID (United States)
3. Idaho National Lab. (INL), Idaho Falls, ID (United States)

The Fluoride salt-cooled High-temperature Reactor (FHR) features a passive decay heat removal system and a high-efficiency Brayton cycle for electricity generation. It typically employs an intermediate loop, consisting of an intermediate heat exchanger (IHX) and a secondary heat exchanger (SHX), to couple the primary system with the power conversion unit (PCU). In this study, a preliminary dynamic system model is developed to simulate transient characteristics of a prototypic 20-MW_th Fluoride salt-cooled High-temperature Test Reactor (FHTR). The model consists of a series of differential conservation equations that are numerically solved using the MATLAB platform. For the reactor, a point neutron kinetics model is adopted. For the IHX and SHX, a fluted tube heat exchanger and an offset strip-fin heat exchanger are selected, respectively. Detailed geometric parameters of each component in the FHTR are determined based on the FHTR nominal steady-state operating conditions. Three initiating events are simulated in this study, including a positive reactivity insertion, a step increase in the mass flow rate of the PCU helium flow, and a step increase in the PCU helium inlet temperature to the SHX. The simulation results show that the reactor has inherent safety features for those three simulated scenarios. It is observed that the increase in the temperatures of the fuel pebbles and primary coolant is mitigated by the decrease in the reactor power due to negative temperature feedbacks. The results also indicate that the intermediate loop with the two heat exchangers plays a significant role in the transient progression of the integral reactor system.

• Research Organization: Idaho National Lab. (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC07-05ID14517; NEUP-128504
• OSTI ID: 1188621
• Report Number(s): INL/JOU-15-35655; TRN: US1500210
• Journal Information: Progress in Nuclear Energy, Vol. 83, Issue C; ISSN 0149-1970
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
HEAT EXCHANGERS
HELIUM
FLUORIDES
PRIMARY COOLANT CIRCUITS
MOLTEN SALT COOLED REACTORS
TRANSIENTS
MATHEMTICAL MODELS
SIMULATION
AFTER-HEAT REMOVAL
BRAYTON CYCLE
FLOW RATE
POWER GENERATION
ELECTRIC POWER
POWER RANGE 10-100 MW
REACTIVITY INSERTIONS
DIFFERENTIAL EQUATIONS
PEBBLE BED REACTORS
DIMENSIONS
REACTOR KINETICS
MASS
REACTOR SAFETY
FHR
TRANSIENT THERMAL-HYDRAULIC ANALYSIS
INTERMEDIATE HEAT EXCHANGER (IHX)
SECONDARY HEAT EXCHANGER (SHX)
MODELING AND SIMULATION