1. Hiroyuki Sekiya June 3-9 2012, Kyoto, NEUTRINO2012 Design of a huge water purification system based on the Super-Kamionade system Hiroyuki Sekiya* for the Hyper-Kamiokande Working Group *Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo Preface: Hyper-Kamiokande (Hyper-K) will be a detector capable of observing CP violation in the Lepton sector, proton decays, atmospheric neutrinos, solar neutrinos, both supernova burst neutrinos and supernova relic neutrinos, and dark matter with sensitivity far that of the Super-Kamioknade(Super-K) detector. Water is the target and signal-sensitive medium of the detector, and thus its quality directly affects the detectors sensitivity. For that reason, water purification is critical to realizing such a huge water Cherenkov detector. SK 1.Hyper-K detector vessel 2. Super-K water system as base design Technical terms / abbreviation 3. Hyper-K water system will process 1.2kt/h Although it takes 35 days to replace the water in the 50kt SK tank, its water transparency is always kept above 100m. Backgrounds are low enough to detect >3.5MeV solar neutrinos. A 5%-level top-bottom asymmetry exists, however the systematic error on the SK energy scale due to this is below 0.1%-level after correction. 39.3m 41.4m 2 cylindrical tanks lying side-by-side (48m x 54m x 250m each) 5 compartments in each tank Total volume 0.99 Mt Fiducial vol. 0.56Mt Total volume 0.05 Mt Fiducial vol. 0.0225Mt Super-Kamiokande IV water system since Feb. 2012 Recirculation rate: 60t/h Reverse osmosis (RO) membrane Filters out ions, contaminants larger than 0.1nm, bacteria etc. (Mixed-Bed) Ion exchanger Uses resin to remove ions such as calcium and uranium Cartridge Polisher(CP) Highly pure ion exchange resins remove all ions from water UV sterilizer(UV) Bacteria sterilization using ultraviolet rays Vacuum degasifier(VD), Membrane degasifier(MD) Removes gases such as Oxygen and Radon Ultrafiltration(UF) membrane Removes nanometer-sized particles Super-K water quality Takes 70 days to fill one cylindrical tank. Takes 35 days to replace the water in the both 0.5Mt tanks. 3.5MeV-4.5MeV Event distribution Return to Water system Purified Water supply Maintaining operation is the first priority To avoid convection, very precisely temperature-controlled (±0.01 o C) water is supplied to the bottom. Rn Free Air (Rn is removed down to mBq/m 3 level by charcoal ) is used for purging. 5 compartments for each tank Water will be recirculated independently in each compartment at 120t/h. The effects of the egg-shape cross section on the water flow will be taken into account when designing the inlet/outlet. Rn Free Air generator (400Nm 3 /h) Water Purification System CompressorsAir dryer 0.3 m filter Buffer tank CO 2 H 2 O remover Charcoal 0.1 m filter 0.01 m filter 0.01 m filter Buffer -40 o C Charcoal purge 0.3kt/h for initial supply 0.6kt/h for recirculation Mine air Mine water Buffer tank 10 m filter Buffer Reverse Osmosis membrane CO 2 remover Mixed-Bed Ion exchange resin Cartridge Polisher Ion exchange resin UV sterilizer Membrane degasifier 1 m filter Chiller w/ T control 1 m filter UV sterilizer Cartridge Polisher Ion exchange resin Ultra-filtration membrane Chiller w/ Temp control UF reject Ultra-filtration membrane Membrane degasifier HK tank r2r2 IonMoleculeMacromoleculeMacro particles Reverse osmosis 0.001 0.01 0.1 110100 1000 Ion exchange Nanofiltration Ultrafiltration Microfiltration Usual filtration Precipitation Size m x 20 UV sterilizer Cartridge Polisher Ion exchange resin Reverse Osmosis membrane Reverse Osmosis membrane Ultra-filtration membrane Membrane degasifier Reverse Osmosis membrane Chiller w/ Temperature control Vacuum degasifier Chiller w/ Temperature control Chiller Mine water Initial supply rate: 30t/h SK tank Super-K IV lowest energy events solar angle distribution Super-K IV Water transparency anti-correlated with Supply water temperature @ Cherenkov light wavelength Measured by decay e - e + from cosmic - + Water quality control Water flow studies are underway Inner detectorOuter detector Volume 370,000m 3 89,000m 3 Flow rate 96.7t/h23.3t/h Number of inlets (outlets) 184 Flow rate/inlet (outlet) 5.375.82 Inlet (outlet) configuration on the top and bottom sections A bad example Finite volume method ANSYS GAMBIT2.4.1+Fluent13.0 ¼ Inner detector Stagnation@center? ¼ Outer detector Downward flow?