Design of a huge water purification system based on the Super- Kamionade system

1. reject drain compensation pump strainer FP-4 FP-5 RO-2 pump RO-2 Design of a huge water purification system based on the Super-Kamionadesystem filter reject (drain) RO-1-1 Primary pump strainer RO-1 pump filter mine water reject (drain) RT-1 RT-3 Rn-free-air dissolving tank RO-3 pump 550 CV-2 RO-3 Hiroyuki Sekiya* for the Hyper-Kamiokande Working Group *Kamioka Observatory, Institute for Cosmic Ray Research, University of Tokyo post RO pump RO water tank HE1 UV sterilizer reject RT-2 RT-4 Ion exchanger 1/2 reject HE3 reject UF reject pump RO-1-2 vacuum degasifier reject 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 detector’s sensitivity. For that reason, water purification is critical to realizing such a huge water Cherenkov detector. 700 HE4 UF reject tank v94 A membrane degasifier Ultrafiltration membrane CV-1 B purified water supply pump A/B Main return pump A/B ID bottom SK 1.Hyper-K detector vessel Technical terms / abbreviation • 2 cylindrical tanks lying side-by-side (48m x 54m x 250m each) • 5 compartments in each tank • 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 41.4m 39.3m 100 10 1 0.1 0.001 0.01 1000 mm Size Microfiltration Ultrafiltration Precipitation Total volume 0.99 Mt Fiducial vol. 0.56Mt Nanofiltration Total volume 0.05 Mt Fiducial vol. 0.0225Mt Reverse osmosis Ion exchange Usual filtration Rn Free Air generator (400Nm3/h) x 20 Mine air 0.1mm filter 0.3mm filter CO2 H2O remover -40oC Charcoal 0.01mm filter 0.01mm filter Buffer Compressors Air dryer Buffer tank Charcoal 3. Hyper-K water systemwill process 1.2kt/h 2. Super-K water system as base design Water Purification System Initial supply rate: 30t/h Mine water Buffer 10mm filter Mixed-Bed Ion exchange resin Reverse Osmosis membrane CO2 remover Reverse Osmosis membrane 0.3kt/h for initial supply Mine water purge purge purge Recirculation rate: 60t/h Reverse Osmosis membrane Buffer tank Chiller w/ T control Cartridge Polisher Ion exchange resin UV sterilizer Ultra-filtration membrane Membrane degasifier 0.6kt/h for recirculation Chiller 1mm filter UV sterilizer UF reject Chiller w/ Temperature control Cartridge Polisher Ion exchange resin purge purge purge Reverse Osmosis membrane Vacuum degasifier Chiller w/ Temperature control Buffer tank Chiller w/ Temp control Ultra-filtration membrane Cartridge Polisher Ion exchange resin UV sterilizer Membrane degasifier 0.6kt/h for recirculation 1mm filter Membrane degasifier Ultra-filtration membrane HK tank Super-Kamiokande IV water system since Feb. 2012 SK tank Super-K water quality • 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. HK tank • Takes 70 days to fill one cylindrical tank. • Takes 35 days to replace the water in the both 0.5Mt tanks. Water flow studies are underway Super-K IV Water transparency Super-K IV lowest energy events solar angle distribution @ Cherenkov light wavelength Measured by decay e-e+ from cosmic m-m+ • 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. anti-correlated with Supply water temperature A “bad” example Finite volume method ANSYS GAMBIT2.4.1+Fluent13.0 Water quality control • Maintaining operation is the first priority • To avoid convection, very precisely • temperature-controlled (±0.01oC) • water is supplied to the bottom. • Rn Free Air (Rn is removed down to • mBq/m3 level by charcoal ) is used • for purging. 3.5MeV-4.5MeV Event distribution Return to Water system Purified Water supply ¼ Inner detector Stagnation@center? ¼ Outer detector Downward flow? r2