He Vessel Cooling Water System Vessel filled w

Decay Volume entrance downstream end 5. 1 m 1. 7 m 1. 4 m

TS Cooling Water Flow Ion Exch. Resin [Not used] * They adsorb Fe ions,

Degasifier and pre-filter system Hollow fiber membrane SEPHAREL EF-040 Px 6 Filter A~D Degasifier

Water System Problems Pre-filter clogging happens so often for TS degasifier. Clogging happens when

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He Vessel Cooling Water System Vessel filled w 1 atm. He gas L=~110 m, V=1, 600 m 3 Target Station Beam Transport From RCS to MLF Muon pit Beam Dump Decay Volume 6 m-thick c oncrete wa ll OA 2 o OA 2. 5 o OA 3 o All apparatus are enclosed in a vacuum/helium vessel, made of carbon steel plates. Iron plates are cooled by “plate coil” water circuits, made of carbon steel Upstream cooling system at Target Station Downstream cooling system at NU 3 T. Ishida(J-PARC center/KEK) 1

Decay Volume entrance downstream end 5. 1 m 1. 7 m 1. 4 m 2009/9/26 “Plate Coil” Water cooling channel U-shaped pipe connection (25 A) 3. 2 mm 3. 0 m 2009/2/27 16 mm Water circuits are separated to upstream (TS) and downstream (NU 3). Each composed of 20 circuits – 40 water channels. T. Ishida(J-PARC center/KEK) 2

TS Cooling Water Flow Ion Exch. Resin [Not used] * They adsorb Fe ions, and possibly erode inside of carbon steel pipes. TS vessel DV DV collimator upstream Primary (Activated) water loop Iron Shields Degasifier is critical to keep soundness of carbon steel plate coils dissolved oxygen O(ppm)→ 1~10 ppb T. Ishida(J-PARC center/KEK) Secondary loop T 2 K Collaboration Meeting @ Toyama, Oct. 08, 2014 Degasifier Critical component To keep soundness of carbon steel pipes 3

Degasifier and pre-filter system Hollow fiber membrane SEPHAREL EF-040 Px 6 Filter A~D Degasifier Filter A’~D’ * Pre-filter system * Pleats filter 10 u x 2 5 u x 2 * 2 sets * Remote flow control nn T. Ishida(J-PARC center/KEK) 4

Water System Problems Pre-filter clogging happens so often for TS degasifier. Clogging happens when beam is ON, and it becomes more frequent with recent high power operation (pre-filter survives only 1~2 weeks) To make degasifier work, need to open bypass flow line this made downstream degasifier membranes contaminated to a few m. Sv/h. Replaced to new ones somehow by minimizing worker’s exposure. Inside of water circuit is coated by black color. It causes a problem for circulation pumps. Need to maintain once/~two years. Need to understand the cause: reinforce filtration system ASAP Replace Irradiated membranes quickly ! Pre-filter clogging with “black powder” (Iron Oxide) + Be 7? T. Ishida(J-PARC center/KEK) Pump maintenance: Impeller coated by black color 5