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Title: Multistep Criticality Search and Power Shaping in Nuclear Microreactors with Deep Reinforcement Learning

Journal Article · · Nuclear Science and Engineering

Reducing operation and maintenance costs is a key objective for advanced reactors in general and microreactors in particular. To achieve this reduction, developing robust autonomous control algorithms is essential to ensure safe and autonomous reactor operation. Recently, artificial intelligence and machine learning algorithms, specifically reinforcement learning (RL) algorithms, have seen rapid increased application to control problems, such as plasma control in fusion tokamaks and building energy management. In this work, we introduce the use of RL for intelligent control in nuclear microreactors. The RL agent is trained using Proximal Policy Optimization (PPO) and Advantage Actor-Critic (A2C), cutting-edge deep RL techniques, based on a high-fidelity simulation of a microreactor design inspired by the Westinghouse eVinciTM design. We utilized a Serpent model to generate data on drum positions, core criticality, and core power distribution for training a feedforward neural network surrogate model. This surrogate model was then used to guide a PPO and A2C control policies in determining the optimal drum position across various reactor burnup states, ensuring critical core conditions and symmetrical power distribution across all six core portions. The results demonstrate the excellent performance of PPO in identifying optimal drum positions, achieving a hexant power tilt ratio of approximately 1.002 (within the limit of <1.02), and maintaining criticality within a 10 pcm range. A2C did not provide as competitive of a performance as PPO in terms of performance metrics for all burnup steps considered in the cycle. Additionally, the results highlight the capability of well-trained RL control policies to quickly identify control actions, suggesting a promising approach for enabling real-time autonomous control through digital twins.

Research Organization:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Organization:
USDOE; USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Nuclear Energy (NE)
Grant/Contract Number:
AC07-05ID14517; NE0009424
OSTI ID:
2515660
Report Number(s):
INL/JOU--24-78765-Rev000
Journal Information:
Nuclear Science and Engineering, Journal Name: Nuclear Science and Engineering Journal Issue: sup1 Vol. 200; ISSN 0029-5639
Publisher:
Taylor & FrancisCopyright Statement
Country of Publication:
United States
Language:
English

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