Investigation of various methods for heat load measurement of ITER prototype cryoline

The cold testing of ITER prototype cryoline (PTCL) is part of technical qualification procedure for multi process pipe ITER cryolines. The detailed plan has been developed for the warm and cold testing of PTCL, which includes pressure and leak test at room temperature followed by cooldown of all the process pipes of PTCL to nominal operating temperature using cold helium. The test infrastructure, which primarily includes 80 K system to supply helium at 30 grams per second (g/s), 6.5 bar and liquid helium Dewar of 5000 liter capacity to supply vapor helium at maximum 1.4 bar and 6 g/s in a controlled manner is at advanced stage of realization. The detailed scheme and methodology for PTCL heat load measurement at 4.5 K and 80 K temperature level using small flow rate and enthalpy difference has been already developed as Plan-A. However, in order to be sure on the measurement of Plan-A, it has been realized to develop back-up plan to ensure the correctness of the measurements. The in-built flexibility of the test infrastructure supports the back-up methods for heat load measurement of PTCL using the same infrastructure. The back-up methods foreseen as Plan-B includes (i) filling the process pipes with low temperature helium gas and evaluating time bound temperature increase and (ii) measuring temperature difference for various heater power using existing electric heaters and extrapolating the results. The present paper details both the plans for the heat load measurement at 4.5 K and 80 K temperature level including the comparison between the two.