29th Symposium on Fusion Technology (SOFT 2016)

P2.116 Actively cooled plasma-facing components and coolant removal system in KSTAR

6 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 116

Poster F. Plasma Facing Components P2 Poster session

Speaker

Eunnam Bang (KSTAR research center)

Description

This paper deals with the first commissioning of active cooling system for plasma-facing components (PFCs) and coolant removal system. During 2015 KSTAR campaign, we have achieved a 55 sec long pulse H-mode. However, some plasma shots were terminated, not because of instabilities or limitation of heating power, but because of safety limit applied to the PFC temperature: upper boundary to lock the system is 400 ˚C to protect the machine, and unlocked at 200˚C. In order to overcome this limitation to achieve longer pulse, an active cooling system is installed. For commissioning, coolant was supplied into the cooling line with 14.0 l/s of mass flow using vacuum vessel cooling system. Temperature of PFCs are monitored by arrays of 200 thermocouples installed at different poloidal and toroidal locations around the torus with a time resolution of 1 sec. With the active cooling, the temperature of lower divertor is about 30˚C lower than that of upper divertor and returned quickly to initial temperature resulting in reduction of shot interval: Inertial cooling takes much longer time to unlock the safety inter-lock. Note that the capavity of current cooling system is about 24.0 l/s and not enough for entire PFCs at this stage: the coolant was supplied only at lower diveror and ploidal limiter sector except of inboard limiter, passive stabilizer, neutral beam armor.One technical issue of this active cooling of PFCs is to remove coolant from the “cooling line”. The cooling line, pipe system inside the PFCs are also used to bake the PFCs. Therefore, a coolant removal system is assembled. The system consists of adsorption dryer (extrnal heater non purge air dryer), gas cooler, pipes and valve components. The flow capacity of adsorption dryer is 3,000Nm³3/hr. The type of gas cooler is shell and tube/plate fin, capavity is 715 Mcal/h.