Truly-Optimized PWR Lattice for Innovative Soluble-Boron-Free Small Modular Reactor

Abstract A novel re-optimization of fuel assembly (FA) and new innovative burnable absorber (BA) concepts are investigated in this paper to pursue a high-performance soluble-boron-free (SBF) small modular reactor (SMR), named autonomous transportable on-demand reactor module (ATOM). A truly optimized PWR (TOP) lattice concept has been introduced to maximize the neutron economy while enhancing the inherent safety of an SBF pressurized water reactor. For an SBF SMR design, the 3-D centrally-shielded BA (CSBA) design is utilized and another innovative 3-D BA called disk-type BA (DiBA) is proposed in this study. Both CSBA and DiBA designs are investigated in terms of material, spatial self-shielding effects, and thermo-mechanical properties. A low-leakage two-batch fuel management is optimized for both conventional and TOP-based SBF ATOM cores. A combination of CSBA and DiBA is introduced to achieve a very small reactivity swing (<1,000 pcm) as well as a long cycle length and high fuel burnup. For the SBF ATOM core, safety parameters are evaluated and the moderator temperature coefficient is shown to remain sufficiently and similarly negative throughout the whole cycle. It is demonstrated that the small excess reactivity can be well managed by mechanical shim rods with a marginal increase in the local power peaking, and a cold-zero shutdown is possible with a pseudo checker-board control rod pattern. In addition, a thermal-hydraulic-coupled neutronic analysis of the ATOM core is discussed.

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Truly-optimized PWR lattice for innovative soluble-boron-free small modular reactor

Scientific Reports ◽

10.1038/s41598-021-92350-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Xuan Ha Nguyen ◽

Seongdong Jang ◽

Yonghee Kim

Keyword(s):

High Performance ◽

Local Power ◽

Pressurized Water Reactor ◽

Pressurized Water ◽

Control Rod ◽

Low Leakage ◽

Small Modular Reactor ◽

Burnable Absorber ◽

Safety Parameters ◽

Atom Core

AbstractA novel re-optimization of fuel assembly and new innovative burnable absorber (BA) concepts are investigated in this paper to pursue a high-performance soluble-boron-free (SBF) small modular reactor (SMR), named autonomous transportable on-demand reactor module (ATOM). A truly optimized PWR (TOP) lattice concept has been introduced to maximize the neutron economy while enhancing the inherent safety of an SBF pressurized water reactor. For an SBF SMR design, the 3-D centrally-shielded BA (CSBA) design is utilized and another innovative 3-D BA called disk-type BA (DiBA) is proposed in this study. Both CSBA and DiBA designs are investigated in terms of material, spatial self-shielding effects, and thermo-mechanical properties. A low-leakage two-batch fuel management is optimized for both conventional and TOP-based SBF ATOM cores. A combination of CSBA and DiBA is introduced to achieve a very small reactivity swing (< 1000 pcm) as well as a long cycle length and high fuel burnup. For the SBF ATOM core, safety parameters are evaluated and the moderator temperature coefficient is shown to remain sufficiently and similarly negative throughout the whole cycle. It is demonstrated that the small excess reactivity can be well managed by mechanical shim rods with a marginal increase in the local power peaking, and a cold-zero shutdown is possible with a pseudo checker-board control rod pattern. In addition, a thermal–hydraulic-coupled neutronic analysis of the ATOM core is discussed.

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Core Design of a Small Pressurized Water Reactor with AP1000 Fuel Assembly Using SRAC and COBRA-EN Codes

Science and Technology of Nuclear Installations ◽

10.1155/2020/8847897 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7

Author(s):

Van Khanh Hoang

Keyword(s):

Safety Margin ◽

Coolant Temperature ◽

Pressurized Water Reactor ◽

Fuel Temperature ◽

Pressurized Water ◽

Control Rod ◽

The Core ◽

Small Modular Reactor ◽

Active Core ◽

And Performance

This paper presents the core design and performance characteristics of a 300 MWt small modular reactor (SMR) with fuel assemblies of the AP1000 reactor. Numerical calculations have been performed to evaluate a proper active core size and core loading pattern using the SRAC code system with the JENDL-4.0 data library and the CORBRA-EN code. The calculated temperature coefficients including fuel temperature, coolant temperature, and isothermal temperature coefficient provide adequate negative reactivity feedbacks. The thermal-hydraulic analysis reveals acceptable radial and axial fuel element temperature profiles with significant safety margin of fuel and clad surface temperature. A safety analysis using the CORBRA-EN code shows that the core will remain covered during the entire transient procedure of the fast transient of remarkably increasing power that would be caused by the ejection of control rod. The analysis results indicate that the core with a cycle length of 2.22 years is achievable while satisfying the operation and safety-related design criteria with sufficient margins.

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Study on Typical Initial Event of ATWS for Small Modular Reactor

Volume 2: Smart Grids, Grid Stability, and Offsite and Emergency Power; Advanced and Next Generation Reactors, Fusion Technology; Safety, Security, and Cyber Security; Codes, Standards, Conformity Assessment, Licensing, and Regulatory Issues ◽

10.1115/icone24-61166 ◽

2016 ◽

Author(s):

Zhang Dan ◽

Ran Xu ◽

Qiu Zhifang ◽

Zhou Ke ◽

Feng Li

Keyword(s):

Optimum Design ◽

Safety Analysis ◽

Accident Analysis ◽

Pressurized Water ◽

Control Rod ◽

Reactor Coolant ◽

Initial Event ◽

Small Modular Reactor ◽

Activation System

The method for ATWS (anticipated transient without scram) analysis was completely developed for commercial pressurized water (PWR) reactor plants, especially for selecting of typical initial events. For accident analysis of ATWS, it is different between PWR and small modular reactor (SMR), as different structures and characters, and it is necessary to study the typical initial events for these reactors. Based on the standard of PWR, the demanding for ATWS analysis was studied and the consequences for typical anticipated transient was calculated using RELAP5/MOD3.2 code, “maintain reactor coolant pressure boundary integrity” was selected as limiting criterion. The results shows for SMR, anticipated transient with the most serious consequence for ATWS are loss of offsite power and inadvertent control rod withdraw event, this conclusion will support to prepare the safety analysis report and optimum design of diversity activation system (DAS) for SMR.

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Prediction of safety parameters of pressurized water reactor based on feature fusion neural network

Annals of Nuclear Energy ◽

10.1016/j.anucene.2021.108803 ◽

2022 ◽

Vol 166 ◽

pp. 108803

Author(s):

Yinghao Chen ◽

Dongdong Wang ◽

Cao Kai ◽

Cuijie Pan ◽

Yayun Yu ◽

...

Keyword(s):

Neural Network ◽

Feature Fusion ◽

Pressurized Water Reactor ◽

Pressurized Water ◽

Water Reactor ◽

Safety Parameters

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Coordinated Control of a Small Pressurized Water Reactor

Volume 1: Operations and Maintenance, Engineering, Modifications, Life Extension, Life Cycle, and Balance of Plant; Instrumentation and Control (I&C) and Influence of Human Factors; Innovative Nuclear Power Plant Design and SMRs ◽

10.1115/icone26-81156 ◽

2018 ◽

Author(s):

Peiwei Sun ◽

Chong Wang

Keyword(s):

Control System ◽

Reactor Core ◽

Reactor Power ◽

Pressurized Water Reactors ◽

Primary System ◽

Pressurized Water Reactor ◽

Pressurized Water ◽

Control Rod ◽

Average Temperature ◽

Water Reactors

Small Pressurized Water Reactors (SPWR) are different from those of the commercial large Pressurized Water Reactors (PWRs). There are no hot legs and cold legs between the reactor core and the steam generators like in the PWR. The coolant inventory is in a large amount. The inertia of the coolant is large and it takes a long time for the primary system to respond to disturbances. Once-through steam generator is adopted and its water inventory is small. It is very sensitive to disturbances. These unique characteristics challenge the control system design of an SPWR. Relap5 is used to model an SPWR. In the reactor power control system, both the reactor power and the coolant average temperature are regulated by the control rod reactivity. In the feedwater flow control system, the coordination between the reactor and the turbine is considered and coolant average temperature is adopted as one measurable disturbance to balance them. The coolant pressure is adjusted based on the heaters and spray in the pressurizer. The water level in the pressurizer is controlled by the charging flow. Transient simulations are carried out to evaluate the control system performance. When the reactor is perturbed, the reactor can be stabilized under the control system.

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