Start-up phase of the HELOKA-LP low pressure helium test facility for IFMIF irradiation modules

Highlights: ► Helium Loop Karlsruhe-Low Pressure (HELOKA-LP) succesfully taken to operation at the end of 2009. ► Verified that HELOKA-LP fulfils all requirements to test the High Flux Test Module (HFTM). ► Some improvements could be done (e.g. reduction of power consumption, enhancement of control path parameters). ► We obtained a chronological sequence of the helium gas impurity which is important for the International Fusion Irradiation Facility (IFMIF). - Abstract: As part of the Engineering Validation and Engineering Design Activities (EVEDA) for the International Fusion Materials Irradiation Facility (IFMIF) , it is foreseen to design and test a 1:1 scale prototype of the IFMIF High Flux Test Module (HFTM) . The module has been designed to be cooled by a low pressure helium gas flowing through minichannels to remove the nuclear heat. The Helium Loop Karlsruhe-Low Pressure (HELOKA-LP) has been designed to provide coolant at 1:1 HFTM operational conditions: massflow 12–120 g/s, inlet pressure 0.3–0.6 MPa, inlet temperature RT – 250 °C. A secondary objective is to use the experience gained with HELOKA-LP for the planning of the IFMIF helium cooling system. The facility has been put into operation in 2009, and has since then been in a test and optimization phase. It was proven, that the above mentioned requirements for the facility are achieved. The paper describes the process layout and components of the facility. The performance is characterized by the results of several steady state and transient benchmark tests. Typical start-up and transition times relevant for the operation mode in the IFMIF irradiation campaigns are obtained. Additionally first results on the impurity ingress and the cooling gas chemistry are described.