Contents lists available at ScienceDirect Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes Overview about cryogenic distillation control and safety approach for Isotopes Separation Facility (ISF) Iuliana Stefan*, Ovidiu Balteanu, Ciprian Bucur, Mihai Vijulie, Nicolae Sofilca, Carmen Moraru, Liviu Stefan, Anisia Bornea, Marius Zamfirache National Research and Development Institute for Cryogenics and Isotopic Technologies – ICSI Rm. Valcea, Rm. Valcea, Romania ARTICLE INFO Keywords: Tritium Cryogenic distillation Process control Fusion ABSTRACT Isotopes separation technologies are used in both Tritium Removal Facilities associated with CANDU reactors (to remove tritium from heavy water) and fusion applications (eq. ITER Isotope Separation System) to recover and enrich tritium for further operation. The expertise gained during design, manufacturing, building, commis- sioning and operation of the Cryogenic Distillation System (CDS) with proprietary four column design built at ICSI Rm. Valcea, could be applied for various tritium recovery applications, regardless of the type of front-end process used, Liquid Phase Catalytic Exchange or Combined Electrolysis and Catalytic Exchange. Cryogenic Distillation feed is a mixture of hydrogen isotopes which presents hazards in operation (explosion and tritium contamination), therefore the CDS of PESTD was designed to meet industrial and nuclear applicable standards. In this paper we present an overview of the CDS focusing on the process control and safety approach which meet specific conditions of Romanian codes and standards required for operation. However, specific information may be used later as reference for design consideration for other CDS. The cryogenic distillation process from ICSI Rm. Valcea is designed as four columns cascade inside a cold-box which acts as second barrier against hydrogen release and thermal insulation. The CDS process control is based on a Programmable Automation Controller (PACs), a Supervisory Control and Data Acquisition (SCADA) and specific low tem- perature field equipment and devices. The control room operator supervises the process using a specific designed Human Machine Interface (HMI) which permits to monitor process parameters, alarms acknowledgment and acts to adjust the process or override normal PACs control. 1. Introduction An Isotopes Separation Facility (ISF) – Pilot Plant for Tritium and Deuterium Separation (PESTD) was developed at ICSI Rm. Valcea based on Liquid Phase Catalytic Exchange (LPCE) process combined with Cryogenic Distillation (CD) process for water detritiation purpose. This facility is a semi-industrial scale research facility designed to remove tritium from heavy water. The main characteristics of the TRF are: hydrogen flow-rate 7.8 Nm 3 /h, process water flow-rate 5 kg/h and hydrogen inventory 15 m 3 [1]. Its purpose is to develop the tritium extraction technology from the heavy water processed in the different types of nuclear reactors or fa- cilities. Based on this technology, Cernavoda NPP initiate in 2004 the first steps for Cernavoda Tritium Removal Facility (CTRF) construction. The goal of this project is to reduce tritium emissions in the en- vironment, to reduce the exposure of the population as well as to de- crease the dose collected by the operators. It is considered that CTRF will reduce the impact of tritium radiation on dose collected by workers with 40 % in the first 3 years and up to 90 % for onsite, similar as WTRF [2]. A TRF also will reduce NPP’s operating costs and the risks for personnel, both in the current operation and during the work for re- actor life extension, by reducing the level of tritium in the moderator. First application of ICSI detritiation facility was to gather data in order to design a facility at industrial scale for Cernavoda NPP, but later these combined technologies were considered for fusion application in Water Detritiation System (WDS) and Isotope Separation System (ISS) plants for ITER. Since the start of ICSI project and during development of CTRF project, several possible solutions were considered for instrumentation and control of a tritium removal facility, in particular for the CD system. As PESTD is a pilot scale plant but still deals with industrial and radiological risk (DTO with 30 Ci/kg, DT gas, T 2 gas) all of them shall be carried out in accordance with the limits and conditions provided by the regulatory authority, The National Commission for Nuclear https://doi.org/10.1016/j.fusengdes.2020.111771 Received 21 September 2019; Received in revised form 14 May 2020; Accepted 15 May 2020 ⁎ Corresponding author. E-mail address: iulia.stefan@icsi.ro (I. Stefan). Fusion Engineering and Design 159 (2020) 111771 0920-3796/ © 2020 Elsevier B.V. All rights reserved. T