Design and Verification of the JUNO Liquid Filling Control System

TL;DR

This paper details the design, implementation, and successful testing of a high-reliability automated liquid control system for the JUNO neutrino experiment, ensuring precise and safe operation of its large-scale detector filling process.

Contribution

It introduces a novel control system architecture combining PLC-based automation, advanced control strategies, and safety features tailored for large underground fluid management in neutrino experiments.

Findings

Flow control stability within 0.5% of setpoint

Rapid stabilization time achieved

System meets safety and reliability requirements

Abstract

Jiangmen Underground Neutrino Observatory (JUNO) is a large-scale neutrino experiment with multiple physics goals including neutrino mass hierarchy, accurate measurement of neutrino oscillation parameters, neutrino detection from supernova, sun, and earth, etc. This paper presents the design, implementation, and verification of a high-reliability automated control system for the liquid Filling, Overflow, and Circulation system in the JUNO experiment. The system is built upon a Programmable Logic Controller architecture, integrated with high-precision sensors and actuators. It implements advanced control strategies, including Proportional-Integral-Derivative regulation, sequential logic, and safety interlocks, to achieve closed-loop control of critical parameters such as flow rate, liquid level, and pressure. Commissioning tests with both pure water and liquid scintillator demonstrate the system's exceptional performance, achieving flow control stability within 0.5% of the setpoint with a rapid stabilization time. The robust design, featuring hardware redundancy and software safeguards, ensures the system meets the stringent requirements for the safe filling and long-term stable operation of JUNO's 20-kiloton central detector and provides a scalable reference for large underground fluid control experiments.