1 / 32

Introduction Commissioning of cooling water system and its operation

T2K Decay Volume Commissioning & Operational Experience T.Ishida , M.Tada & Y.Yamada Neutrino Experimental Facility Group J-PARC / KEK [CONTENTS]. Introduction Commissioning of cooling water system and its operation Vessel evacuation and He filling Summary . 1. Introduction.

sabine
Download Presentation

Introduction Commissioning of cooling water system and its operation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. T2K Decay VolumeCommissioning & Operational ExperienceT.Ishida, M.Tada & Y.YamadaNeutrino Experimental Facility GroupJ-PARC / KEK[CONTENTS] • Introduction • Commissioning of cooling water system and its operation • Vessel evacuation and He filling • Summary

  2. 1. Introduction

  3. Neutrino Secondary Beam-line Vessel filled w 1atm. He gas L=~110m,V=1,600m3 • Target Station(TS), Decay Volume(DV), & Beam Dump(BD) • TS: He-cooled graphite target, 3 magnetic horns, remote maintenance • DV: 94m-long tunnel with rectangular cross section • BD: hadron absorber made of large graphite blocks, surrounding iron shields • All the apparatus are enclosed in a gigantic vacuum/helium vessel, made of carbon steel plates. • He atmosphere aims to prevent nitrogen oxide (NOx) production / oxidization of apparatus. • Iron plates of the vessel are cooled by water circuits. • Maintenance is not possible after beam operation due to irradiation. • Radiation shielding / cooling capacity were designed to accept up to ~4MW beam (w/o safety margin). Target Station Muon pit Beam Transport From RCS to MLF Beam Dump Decay Volume OA2o OA2.5o OA3o 6m-thick concrete wall

  4. Target Station (TS) • Horns / a baffle are supported from the wall of vessel by support modules. • Apparatus on the beam-line are highly irradiated after beam. Remote maintenance is key issue. Large flange, sealed with Al plates, t= 120mm Service Pit 1.0m Concrete blocks Beam window Ti-alloy Water-cooled iron cast blocks 29pcs. total 470t 2.3m Horn-3 Horn-2 10.6m Horn-1 Beam Support Module Target OTR Baffle Graphite Collimator DV collimator 15.0m Disassemble @ maintenance area

  5. Horns in the TS Vessel Horn-2 [downstream] Horn-3 [upstream] • Integrated # of pulses (~Run-3): 7~8M • Current stability ~2% remote Connections Horn ~ support Clearances ~30mm Supply helium ducts covering bus-bars Flow rate (entire He vessel): 2,400m3/h Water cooling: Heat load @ 750kW at most ~45 oC • Alignment precision of horns : • 0.3mm(x), 1mm(y), 1mm (z-beam) Photos on Sep., 2009 (before Physics Run)

  6. Decay Volume • Water circuits are separated to upstream and downstream. • Each composed of 20 circuits – 40 water channels. 1.4m • entrance • downstreamend 1.7m “Plate Coil” Water cooling channel 2009/9/26 5.1m U-shaped pipe connection (25A) 3.2mm 3.0m 2009/2/27 16mm

  7. Plumbing at μPit [West side wall] • Control water flow of 260water channels (130 circuits), ~500 Valves (25A) • Though it is designed to use half of the circuits for 750kW beam, we forced to use all channels with low flow rate. • It may cause troubles for carbon steel, if we remove water from the channels. • To Decay Volume • (downstream) TP -5.1m • To BD • Upstream shield • To Absorber • cooling modules TP -12m • Supply • header • Return • header

  8. 2. Commissioning of cooling water system and its operation

  9. Cooling Water System at NU3[downstream DV + BD] • Industrial • water • supply • Purified • water • supply • Outside • yard • [GL] • Similar system at TS • Tertiary • Cooling • towers • N2 gas • supply • for ET • Expansion • tank • Hot • machine • room • [1F] • Heat • exch. • Secondary • Degasifier • Hollow fiber membrane • [+ 0.5um Pre-filter] • Exp. tank • [Water supplier] • [B1F+4.5m stand] • Centrifugal • pumps • Ion-exchange resins • [+ 0.5um Pre-filter] • Superhot • machine • room • [B1F] • HEX • Temporary pump + • filter system • for flushing • [later moved to B1F] • Primary • (Activated) • DV/BD • Muon pit • [B2F] • Header

  10. Water System Commissioning (Mar.2009) • Initial flushing with industrial water (Mar.12) • Remove dusts/rusts AFAP by independent circuit with a pump and filters (with purified water) • ASA the water becomes clean, start operation of the main water system (Apr.3) • Switch on degasifier to stop corrosion (Apr.6) • Switch on ion exchange resin system (Apr.14) Pump Apr. 1 Bag-type filter/strainer (5um) Mar. 13 Cooling water system is running continuously in basis, except for the shutdown due to the earthquake (Mar.~Jun. 2011) and repair works (Jun.~Sep.2012). Serial Pleats filters(0.5um) B2F

  11. Water System Operation • Water is clean and transparent. No corrosion observed so far. • It may owe to the vacuum degasifier: dissolved oxygen O(ppm)→1~10ppb • No corrosion even after the ~3month shutdown by the earthquake • Problem: inside of circuit is coated by black color. • We were forced to curve impellers/casings of the centrifugal pumps. • We stopped to use ion exchanging resins since Sep.2009 • Resistivity: In 1.2 /Out 18 MΩ・cm(Apr.14,’09) Out 13 MΩ・cm(Sep.14’09) • They may just adsorb Fe ions, and thus erode inside of carbon steel pipes. Chemical solutions in the primary cooling water (with resin operated): mostly powder(solid), not solution. May 1,’09 Aug.20’09 0.2mg / litter  2g-Fe / 10m3 Flow meter of degasifier (Jul. 2009) Strainer mesh (Sep. 2012)

  12. Pump Repair (Curve Impeller/Casing)[Dec.26-27, 2010 for pump-1]

  13. Radiation Issues • Radioactive nuclei in the primary cooling water • Run-3: Mar.~Jun.9, 2012 (4month), 1.6x1020pot, -190kW • Measured on Jun.13(+4d). Only 3H is beyond limit for disposal. • So far daughters of Fe is not serious problems. • Residual dose in the B1 super-hot machine room • Jun.11, 2012 (+2days after beam) • Pre-filter of degasifier: 600uSv/h  Degasifier itself (Hollow fiber membrane Module x 6) : 20~45uSv/h • The 0.3um pleats filter seems to be effective to adsorb 7Be • On Sep.2012, we have duplicated the pre-filter and moved into a compartment of iron shields for resins (not used) DP tank:1 Resins(not used) PostFilter:10 PreFilter:60 600uSv/h 20-45 HEX:28 55(IC) Pump:2(IC)

  14. Degasifier • Hollow fiber membrane • SEPHAREL EF-040P x 6 • 0.3um pleats pre-filters moved into compartment of resins • (Sep. 2012)

  15. How to detect water leak ? • Leak sensors installed at a drain port of the Helium vessel. • Total amount of water-supply to the expansion tank is monitored. • We found 20 litter/day (~1 water drop/sec) water leak at one drain valve. • This will also be a good way to identify bad water circuits. Nov.14, 2009 Litters supplied in total

  16. 3. Vessel evacuation and He filling

  17. Vessel Evacuation / Leak Test • Evacuation test (Feb. 3~18,’09): • The vacuum saturated w ~50Pa (Spec value: <13Pa) • Leak found by helium leak detector at connection of BD/DV, where very complicated welding pattern was used. • Repaired, but no time to continue helium leak tests. He-spraying pipes pre-installed in dump pit for further tests. • Ceiling of dumppit closed on Feb.18th, 2009. Feb.15 2009 3 Mechanical-booster pumps @ TS B1 stand BD-top BD-upstr. (top) BD-side DV BD-upstr. (side)

  18. Evacuation for He filling[Oct.2009] • 1st experience to evacuate with full-setup • All horns & iron/concrete shield blocks, feed-through / piping. • Vacuum saturated at 80~90 Pa in a week. • The leak at BD was NOT fixed. At most 10-2~10-1 Pa・m3/s=1~10ppmO2/d • Aggravation rate was 43~46 Pa/h: 20 Pa・m3/s Restart evacuation （16th 17:30～） 730Pa8:05 Rate= 46.0Pa/h (ave 13.8hrs) 2nd trial in Oct.’09 Separate Horns （17th 10:00）@240Pa He leak tests btw Horn & Vessel (put He gas in horns) 260Pa 94Pa 18:15 91Pa Pump stopped by mistake 10：40 81 Pa 86 Pa

  19. Test Outgas Measurements 60 kg scale dM =1g 495Φｘ1,000L V=0.192 m3 S=1.94 m2 • BG 12Pa/h =3.3x10-4 Pa・m3/s/m2→ Vessel (1,700m2) 0.6 Pa・m3/s • Block 47(-12)Pa/h = 1.0x10-2 Pa・m3/s/m2→ Shield(240m2) 3 Pa・m3/s • The values are still not consistent to 20 Pa・m3/s, but maybe comparable. Cf. Block weight: 0.023%/d →Shield(130t) 45 Pa・m3/s (assume all vapors remain) Block w paint V=6e-3 m3 13 kg Reduced -3g /day by evacuation Pump N2 gas for purge

  20. Helium gas filling (Oct.29, 2009) • Filling was going very smoothly, finished in 2 hrs • An oxygen content meter and a dew point meter were set up in the drain pit of the mupit (now at B1F)

  21. Oxygen Content / Dew point • Oxygen raised + 10ppm / 1day, but we notified • Positive correlation with atmospheric pressure • The raise stopped after adding +1kPa of more helium. • In later fillings we succeeded to keep vessel under 100ppm of oxygen • Dew point > 20 degC, almost saturated. DewP. 170 ppm Oxygen Atm. pressure He pressure +10 hPa 1030hPa 110ppm 1010hPa 130ppm 10/31 11/4

  22. Reduce HTO during maintenance • After Run-2 (1.1x1020pot, vessel was evacuated and air was filled (apr.27-28, 2011). After a month, HTO raised up to ~1Bq/cc • Cf. Limit to work (J-PARC): 500mBq/cc (16uSv/h internal exposure) • Cf. Limit for exhaust (J-PARC): 5mBq/cc in 3 month average. (X500 diluted.) • Before opening vessel, we send dried air (30m3/h) from NU3. • During maintenance, vessel air is sucked (28m3/h) to NU3. May 26, 2011 Room-Gas Monitor (Affected by Rn) 1.33 Bq/cc 1d 0.86 Bq/cc 2d June 16, 2011 0.55 Bq/cc 0.25 Bq/cc 0.64 Bq/cc 5d 0.21 Bq/cc 4d 0.38 Bq/cc 0.24 Bq/cc Ready to open vessel Sampled gas measurements 710 mBq/cc →270 mBq/cc 360 mBq/cc →185 mBq/cc ? mBq/cc →136 mBq/cc 1000 mBq/cc →490 mBq/cc

  23. Dry air supplier at NU3 Water/Mist filters compressor He Vessel F • ~500ℓ/min, dew point < -10deg refrigerated dryer Hollow fiber membrane Hollow Fiber Membrane Dryer 3H monitor 194mBq/cc 48mBq/cc DewP +16℃ Refrigerated dryer 7/8 7/11 Dry air -5℃

  24. Vessel Exhaust Line at NU3 HEPA filter Water separator To HEPAfilter filter ~470ℓ/min 680m3/day He Vessel Pump F Exhaust From Vessel Flow meter Spec: 876ℓ/min 3H monitor Pre filter Water separator Sample port 3H monitor

  25. 4. Summary • The T2K secondary beam-line is enclosed in a giant vacuum vessel, made of carbon steel, cooled by water, and filled with 1atm. Helium. • It is the first experience for our community, how to operate such a delicate, and possibly fragile, system. • Commissioning & operation of water circulation system is reviewed. • Water is clean enough so far, and no serious corrosion observed. It may thanks to the vacuum degasifier. • Whole the water lines are filled with water: it will double the radiation waste water: Desirable (but not essential) to study how to make half of pipes empty without damaging carbon steel. • Radioactive nuclei in the primary water: 3H production is only deal. Fe daughters are few.

  26. Summary (Cont.d) • Vessel evacuation / He gas filling • Oxygen contamination of 10ppm/day was observed at commissioning • Consistent to the He leak test result at the BD pit (10-1 Pa・m3/s) • Air contamination can be suppressed by keeping vessel pressure slightly higher than atmospheric pressure. • Established the way to keep oxygen under requirement (~100ppm) • Dew point in the vessel > 20 deg.C, almost saturated. • The rate of the observed pressure rise (20 Pa・m3/s) may be caused by the water vapor from concrete blocks in the vessel. • He purification system (molecular sieve / cold trap ) is desirable to prevent 3H production. • Decay volume / beam dump after the earthquake • During 2011 shutdown: Inspection by Web-camera + LED • During 2012 shutdown: Expansion joint was repaired, whole flexible tubes replaced. • Entire system now running for Run-4 !

  27. Visual Inspection of DV/BD[Summer, 2011] 36W LED, 3,600lm illuminating angle10deg MOS sensor, min.illuminance=0.5lx X36 (18x2EX) optical zoom lx

  28. Visual Inspection of DV/BD (2)

  29. Vessel He contaminated by air[2012 March.] • Helium was contaminated by air ~2.5% (0.5% O2) • Small amount of NOX can be produced. • We will replace He anyway this summer to dilute 3H. Thin Pipe was broken (~Mar.9) Due to vibration of the Newly introduced Metal bellows pump Support and flexible tube is introduced To absorb vibration.

  30. He Vessel Leak • It may be the reason of bad OTR image…

More Related