Distillation and stripping pilot plants for the JUNO neutrino detector: design, operations and reliability

TL;DR

This paper details the design, operation, and reliability assessment of pilot plants for liquid scintillator purification, aiming to optimize processes for the JUNO neutrino detector's large-scale system to achieve high optical clarity and radiopurity.

Contribution

It introduces the design and operational insights of pilot plants that inform the development of full-scale purification systems for neutrino detector scintillators.

Findings

Pilot plants demonstrated reliable operation of key components.

Purification processes achieved target optical attenuation length.

Data supports scaling up for JUNO's full-scale system.

Abstract

This paper describes the design, construction principles and operations of the distillation and stripping pilot plants tested at the Daya Bay Neutrino Laboratory, with the perspective to adapt this processes, system cleanliness and leak-tightness to the final full scale plants that will be used for the purification of the liquid scintillator used in the JUNO neutrino detector. The main goal of these plants is to remove radio impurities from the liquid scintillator while increasing its optical attenuation length. Purification of liquid scintillator will be performed with a system combining alumina oxide, distillation, water extraction and steam (or N2 gas) stripping. Such a combined system will aim at obtaining a total attenuation length greater than 20 m at 430 nm, and a bulk radiopurity for 238U and 232Th in the 10-15 to 10-17 g/g range. The pilot plants commissioning and operation have also provided valuable information on the degree of reliability of their main components, which will be particularly useful for the design of the final full scale purification equipment for the JUNO liquid scintillator. This paper describe two of the five pilot plants since the Alumina Column, Fluor mixing and the Water Extraction plants are in charge of the Chinese part of the collaboration.