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Scaling Gd Filtration Technology for WATCHMAN: Efficient Gadolinium Removal and Selective Filtration System

This article discusses the development of a scalable filtration system for the WATCHMAN project, focusing on efficient gadolinium removal and selective filtration. The prototype system at UC Irvine has shown promising results. The article also mentions the EGADS project and the design work for the water system in WATCHMAN.

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Scaling Gd Filtration Technology for WATCHMAN: Efficient Gadolinium Removal and Selective Filtration System

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  1. Perpetual Ocean Machine:Scaling Gd FiltrationTechnology for WATCHMAN Mark Vagins UC Irvine/Kavli IPMU 3rd Full WATCHMAN Collaboration Meeting Blacksburg, VA May 1, 2014

  2. To make WATCHMAN work, we will have to: Dissolve gadolinium sulfate (Gd2(SO4)3) in water Easy and fast (pH control/use octahydrate) Remove the gadolinium efficiently and completely when desired  Also easy and fast (pH control/DI resin) Keep pure water pure yet retain gadolinium in solution  The tricky part; need a selective Gd filtration system

  3. Electrical Band-Pass Filter

  4. Molecular Band-Pass Filter (2007) Gd2(SO4)3 (NF Reject) Gd2(SO4)3 plus smaller impurities (UF Product) Pure water plus Gd2(SO4)3 Ultrafilter(10-100 nm pore size) Nanofilter(1-10 nm pore size) Impurities larger than Gd2(SO4)3 (UF Reject flushed periodically ) Impurities smaller than Gd2(SO4)3 (NF Product) Reverse Osmosis (0.5 – 1.5 nm pore size) Pure water (RO product) plus Gd2(SO4)3 Larger and smallerimpurities to drain (UF Flush + RO Reject)

  5. August 2009 “Band-pass Filter” Gd2(SO4)3 (NF#1 Reject) Gd2(SO4)3 plus smaller impurities (UF Product) water plus Gd2(SO4)3 from main tank Ultrafilter Nanofilter #1 Impurities larger than Gd2(SO4)3 trapped in UF (UF Reject flushed periodically ) DI T O C Nanofilter #2 Gd2(SO4)3 (NF#2 Reject) Impurities to drain (UF Flush) RO #1 Pure water (RO product) plus Gd2(SO4)3 back to tank Reject Tank RO Reject to small tank DI RO #2

  6. Prototype Selective Filtration Setup @ UCI The design works well. It is the world’s first operational selective filtration system.  Water quality is indefinitelymaintained/improved, with or without gadolinium.  There is <60 ppb loss of Gd per cycle. However, this prototype system at UCI processes just 0.2 tons of water per hour. It must be scaled up by a factor of ~375 to be of use in WATCHMAN…  …happily, this work is well underway!  Membrane Pre-Flush Reverse Osmosis Nanofilter #1 Nanofilter #2 Ultrafilter

  7. EGADS at Kavli IPMU (total funding to date = $6,000,000) Super-Kamiokande EGADS Facility Super-K Water system EGADS Hall (2500 m^3) • In the Kamioka mine next to Super-K we have built a dedicated 200-ton gadolinium demonstrator project called EGADS – Evaluating Gadolinium’s Action on Detector Systems. 12/2009 2/2010 6/2010 12/2010 The EGADS water system processes 5 tons per hour of Gd-loaded water. It is a direct 25X scale-up of the UCI prototype.So, another scaling factor of 15 or so is needed for WATCHMAN.

  8. ;. Main 200-ton Water Tank with 227 50-cm PMT’s + 13 HK tubes(PMT’s installed in summer of 2013) 15-ton Gadolinium Pre-treatment Mixing Tank Selective Water+Gd Filtration System 11/2011

  9. Gd loading of the 200-ton tank • Feb. 6th, 2013: Inject first 30 kg of Gd2(SO4)3*8H2O • Feb. 13th: Inject another 30 kg (60 kg total) • March 6th: Inject 29.4 kg (89.4 kg total) • March 20th/21st: Inject 60 kg (149.4 kg total) • April 1st/2nd: Inject 124.6 kg (274 kg total) April 16th20th: Inject 126 kg (400 kg total) World record: Largest single quantity of gadolinium in solution!

  10. 100% 80% 60% 40% 20% 0% Thermal neutron capture cross section (barns) Gd =49700 S =0.53 H =0.33 O =0.0002 Captures on Gd 400 kg  88% 274 kg  83% 149.4 kg  73% 89.4 kg  62% 60 kg  52% 30 kg of Gd2(SO4)3 8H2Oin 200 tons 35% captureon gadolinium Gd in Water 0.0001% 0.001% 0.01% 0.1% 1%

  11. Percentage of light remaining after 15 meters of travel SK-III and SK-IV Ultrapure Water = 74.7% - 82.1% @ 15 m 60 kg of Gd2(SO4)3*8H2O 52% n capture on Gd 89.4 kg of Gd2(SO4)3*8H2O 62% on Gd 149.4 kg of Gd2(SO4)3*8H2O 73% on Gd 274 kg of Gd2(SO4)3*8H2O 83% on Gd 400 kg of Gd2(SO4)3*8H2O 88% on Gd 30 kg of Gd2(SO4)3*8H2O 35% n capture on Gd 15 meters is a characteristic distance in big WC detectors Gadolinium’s light attenuation is acceptable 

  12. We then drained the tank to prepare for PMT installation. Looking down into the EGADS tank after four months of gadolinium exposure. No rust!

  13. EGADS PMT installation; August 2013

  14. Working Inside the EGADS Tank; August 2013

  15. Looking Down Into the Completed EGADS Detector; August 2013 Insert: Event Display of a Downward-Going Cosmic Ray Muon

  16. After building the Gd water system for EGADS, South Coast Water got the contract for designing WATCHMAN’s water system. SCW CEORoy Hall They previously built the pure water systems for: IMB, Milagro, E261a/b (the 1994 KEK beam test experiment), K2K’s 1KT detector, and LUX They also operate the fresh air system for SK/XMASS/EGADS. SCW’s ~1000 active accounts include the US Navy, hospitals, semiconductor fabrication plants, and even a few movie stars.

  17. Industrial water input during fill, water fromWATCHMAN tank during recirculation My interpretationof SCW’s preliminary design for a WATCHMANwater system Uranium Removal,DI and UV Pre-treatment and UF/NF/RO To WATCHMAN: 18 tons/hr  fill in 8 days, turn over in two dayswith fast recirc (not shown) Chiller and Degas Detailed design later this year

  18. WATCHMANMembraneRack(1 of 15) EGADS Selective Filtration System Based on years of experience with EGADS - and byusing modular components - scaling up by the additional order of magnitude needed for WATCHMAN should be straightforward.

  19. In conclusion: Selective Water Filtration System • The 400 kg of Gd2(SO4)3 recently circulated in the 200-ton EGADS tank is the largest single quantity of gadolinium ever placed into solution… anywhere. No issues during loading. • This is also the first Gd2(SO4)3 in a stainless steel tank. No surprises, no problems, no corrosion. • After initial injection it rapidly became uniformly distributed – no “stratification” issues. • The prototype band-pass water system at UCI has been modularized and successfully scaled up 25X for EGADS. Like the prototype it operates without loss of water or Gd.Fully loaded water transparency within 15% of ultrapure H2O. • After seven years (and millions of dollars) of development, the 200-ton Gd selective filtration system is working very well. Proven EGADS design ready to scale for use by WATCHMAN.

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