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

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-MWth 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 thatmore » 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.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3]
  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)
Publication Date:
OSTI Identifier:
1188621
Report Number(s):
INL/JOU--15-35655
Journal ID: ISSN 0149-1970; TRN: US1500210
DOE Contract Number:
AC07-05ID14517; NEUP-128504
Resource Type:
Journal Article
Resource Relation:
Journal Name: Progress in Nuclear Energy; Journal Volume: 83; Journal Issue: C
Publisher:
Elsevier
Research Org:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
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