Preferred core conceptual design of pebble bed advanced high temperature reactor
Introduction
Six fourth generation nuclear reactors, including Molten Salt Reactor (MSR), Gas-cooled Fast Reactor (GFR), Lead-cooled Fast Reactor (LFR), Sodium-cooled Fast Reactor (SFR), Supercritical Water-cooled Reactor (SCWR), Very-High Temperature Reactor (VHTR), were selected from more than 100 types of reactors in 2002, considering sustainability, economy, safety, reliability and nuclear non-proliferation. The pebble bed advanced high temperature reactor (PB-AHTR) is an advanced high temperature reactor cooled by molten salt, combining MSR and VHTR. It has several characteristics, including molten salt cooling, TRISO (Tristructural isotropic coated fuel particles) fuel, passive cooling safety system, supercritical water circulation system and conventional island design (Wang et al., 2019). PB-AHTR meets requirements of the fourth generation nuclear reactor because of the inheritance of advantages and technical foundations of existing reactors. In addition, the commercial application of PB-AHTR is also highly feasible under existing circumstances. The core of the PB-AHTR is a pebble bed. Several researches about the pebble flow and heat transfer of pebble bed have been conducted (Jiang et al., 2019, Wu et al., 2017, Latifi et al., 2020). These researches provide the foundation of this paper.
Core design researches of PB-AHTR have been conducted in this paper. Key parameters and core designs of PB-AHTR are analyzed and evaluated. A preferred conceptual design of the PB-AHTR core is proposed.
Section snippets
Core design code
A large number of literatures have applied Monte Carlo code to investigate the design of pebble bed high temperature reactors (Huda and Obara, 2008, Auwerda et al., 2010). The criticality calculation and burn-up calculation for core design of PB-AHTR is performed by the Monte Carlo transport code RMC (Wang et al., 2015, Wang et al., 2017) in this study. RMC is developed by Tsinghua University as a tool for reactor core analysis on high-performance computing platforms. RMC has such functions as
Overall parameters of core
In this paper, the overall parameters of the PB-AHTR core are listed, including 10 MW thermal power, 2LiF-BeF2 molten salt coolant, same spherical fuel elements as the high temperature gas cooled reactor. As for the fuel sphere, TRISO coated particulate fuel and graphite base is used with 6.0 cm diameter, 17.0 wt% 235U enrichment and 7.0 g uranium loading amount per fuel sphere. These parameters are based on HTR-10, which is a validated experimental pebble-bed reactor in operation (Xie et al.,
Preferred core design
One-time loading scheme is simpler than the batch loading scheme. In the one-time loading scheme, compared with the core injecting poisonous molten salt, evacuating the molten salt is more practical. If the core is injected with poison, the core will be contaminated, and the entire reactor is scrapped. In order to meet the requirements of the first set and the second set of shutdown systems at the same time, the final core loading height of the active zone is 160 cm, and the second set of
Conclusions
This paper investigates and conducts a series of studies on the second shutdown systems and core fuel loading of PB-AHTR. The key parameters of PB-AHTR core are studied, and the preferred core conceptual design is proposed. Both evacuating molten salt and injecting poison into coolant can be used as the auxiliary system of the second shutdown system in PB-AHTR. Compared with injecting poison into coolant, the effect of evacuating molten salt on the core is smaller and more beneficial to the
CRediT authorship contribution statement
Lianjie Wang: Conceptualization, Methodology, Software. Wei Sun: Conceptualization, Methodology. Bangyang Xia: Conceptualization, Methodology. Yang Zou: Conceptualization, Software. Rui Yan: Conceptualization, Software.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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Cited by (1)
Fluoride-salt-cooled high-temperature reactors: Review of historical milestones, research status, challenges, and outlook
2022, Renewable and Sustainable Energy ReviewsCitation Excerpt :The fuel pebbles of PB-AHTR in the fluoride salt coolant were floated by buoyancy. The fuel pebbles pass through the reactor core from the bottom to the top [13]. In 2010, the concept design of the small modular advanced high-temperature reactor (SmAHTR) was completed by ORNL.