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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. - PowerPoint PPT Presentation
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Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
T2K Decay VolumeCommissioning &
Operational Experience
T.Ishida, M.Tada & Y.Yamada Neutrino Experimental Facility
GroupJ-PARC / KEK
[CONTENTS] 1. Introduction2. Commissioning of cooling
water system and its operation3. Vessel evacuation and He
filling4. Summary
1
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
1. Introduction
2
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Neutrino Secondary Beam-line
Target Station(TS), Decay Volume(DV), & Beam Dump(BD)TS: He-cooled graphite target, 3 magnetic horns, remote maintenanceDV: 94m-long tunnel with rectangular cross sectionBD: 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).
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Decay Volume
Target Station
Beam Dump
Vessel filled w 1atm. He gasL=~110m,V=1,600m3
OA2o
OA2.5o
Beam TransportFrom RCS to MLF
6m-thick concrete wallOA3o
Muon pit
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Target Station (TS)
4
15.0m
10.6
m
BaffleGraphiteCollimator
Horn-1 Horn-2 Horn-3Beam windowTi-alloy
DV collimator
Large flange, sealed with Al plates, t= 120mm
1.0m Concrete
blocks
Water-coolediron cast blocks 29pcs. total 470t
Support Module
2.3m
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.
Service Pit
Disasse
mble
@ maintenance area
OTR Target
Beam
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Horns in the TS Vessel
Integrated # of pulses (~Run-3): 7~8MCurrent stability ~2%
5
Photos on Sep., 2009 (before Physics Run)
Horn-2[downstream]
Horn-3[upstream]
remoteConnections
Horn ~ support
Supply helium ductscovering bus-barsFlow rate (entire He vessel):2,400m3/h
Energy deposit
Joule heat
Total(kW)
Horn1 11.3 12.7 24.0Horn2 5.4 4.5 9.9Horn3 1.6 3.0 4.6
Water cooling: Heat load @ 750kW
at most~45 oC
• Alignment precision of horns : 0.3mm(x), 1mm(y), 1mm (z-beam)
Clearances ~30mm
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Decay Volume
Water circuits are separated to upstream and downstream.Each composed of 20 circuits – 40 water channels.
6
2009/2/27
downstream end
3.0m
5.1m2009/9/26
entrance1.4m
1.7m
“Plate Coil”Water cooling
channel
3.2mm
16mm
U-shaped pipe connection (25A)
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Plumbing at μPit
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.
Supply header
Return header
To Decay Volume (downstream)
To BDUpstream shield
To Absorber cooling modules
[West side wall]
TP-12m
TP-5.1m
7
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
2. Commissioning of cooling water system and
its operation
8
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
Cooling Water System at NU3
[downstream DV + BD]
Similar system at TS
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Superhot machine
room[B1F]
Hot machine room [1F]
Tertiary
Secondary
Heatexch.
HEX
Cooling towers
Purified water supply
N2 gas supplyfor ET
Outside yard[GL]
Expansion tank
Exp. tank[Water supplier]
DegasifierHollow fiber membrane[+ 0.5um Pre-filter]
Ion-exchange resins[+ 0.5um Pre-filter]
Muon pit[B2F]
Primary(Activated)
Temporary pump + filter system for flushing
[later moved to B1F]
Industrialwater supply
Header
DV/BD
[B1F+4.5m stand]
Centrifugal pumps
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
Water System Commissioning (Mar.2009)
1. Initial flushing with industrial water (Mar.12)2. Remove dusts/rusts AFAP by independent circuit with a pump
and filters (with purified water)3. ASA the water becomes clean, start operation of the main
water system (Apr.3) 4. Switch on degasifier to stop corrosion (Apr.6) 5. Switch on ion exchange resin system (Apr.14)
Mar. 13
Apr. 1
Serial Pleats filters(0.5um)
Bag-type filter/strainer (5um)
B2F
Pump
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).
10
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Water System Operation
Water is clean and transparent. No corrosion observed so far.It may owe to the vacuum degasifier: dissolved oxygen O(ppm)→1~10ppbNo 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.2009Resistivity: 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.
Flow meter of degasifier(Jul. 2009)
Chemical solutions in the primary cooling water (with resin operated): mostly powder(solid), not solution. May 1,’09 Aug.20’09
Strainer mesh(Sep. 2012)
11
0.2mg / litter 2g-Fe / 10m3
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
Pump Repair (Curve Impeller/Casing)
[Dec.26-27, 2010 for pump-1]
12
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Radiation Issues
Radioactive nuclei in the primary cooling waterRun-3: Mar.~Jun.9, 2012 (4month), 1.6x1020pot, -190kWMeasured 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 roomJun.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)
13
Spc. 3H 7Be 22Na 52Mn 54Mn 48V 46Sc 51Cr 43KBq/cc 800 2.1 0.040 0.011 0.072 0.027 0.013 0.11 0.011
Disp.limit 60 30 0.3 0.5 1 0.4 0.6 20 3
Life 12.3y 53.2d 2.6y 5.6d 312d 16d 83.8d 27.7d 22.3h
600uSv/hHEX:28
Pump:2(IC)
20-45
55(IC)
PreFilter:60PostFilter:10
Resins(not used)
DP tank:1
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Degasifier
14
Hollow fiber membraneSEPHAREL EF-040P x 6
0.3um pleats pre-filters moved into compartment of resins(Sep. 2012)
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK 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.
Litters supplied in total
Nov.14, 2009
15
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
3. Vessel evacuation and He filling
16
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK 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 dump pit closed on Feb.18th, 2009.
BD-side
DV
BD-top
BD-upstr.(top)
BD-upstr.(side)
Feb.15 2009
17
3 Mechanical-booster pumps@ TS B1 stand
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
Evacuation for He filling[Oct.2009]
18
Restart evacuation( 16th 17:30 ~)
Separate Horns( 17th 10:00 ) @240Pa
91Pa Pump stopped by mistake
260Pa
94Pa18:15
730Pa 8:05Rate= 46.0Pa/h(ave 13.8hrs)
86 Pa 10 : 4081 Pa
He leak testsbtw Horn & Vessel(put He gas in horns)
1st experience to evacuate with full-setupAll 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/dAggravation rate was 43~46 Pa/h: 20 Pa ・ m3/s
2nd trial in Oct.’09
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Test Outgas Measurements
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/sThe 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)
19
Block w paint V=6e-3 m3 13 kg Reduced -3g /day by evacuation
N2 gas for purgePump
495Φ x 1,000LV=0.192 m3
S=1.94 m2
60 kg scaledM =1g
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
Helium gas filling (Oct.29, 2009)
Filling was going very smoothly, finished in 2 hrsAn oxygen content meter and a dew point meter were set up in the drain pit of the mupit (now at B1F)
20
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
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.
Oxygen
He pressure+10 hPa
Atm. pressure
DewP.
10/31
130ppm1010hPa 1030hPa
170 ppm
110ppm
11/4
21
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
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.
22
1000 mBq/cc→490 mBq/cc
4d 0.21 Bq/cc
710 mBq/cc→270 mBq/cc
360 mBq/cc→185 mBq/cc
? mBq/cc→136 mBq/cc
1.33 Bq/cc
June 16, 2011
May 26, 2011
0.86 Bq/cc0.55 Bq/cc 0.25 Bq/cc5d
2d1d
0.64 Bq/cc0.38 Bq/cc 0.24 Bq/cc
Room-Gas Monitor (Affected by Rn)
Sampled gas measurements Ready to open vessel
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Dry air supplier at NU3
~500ℓ/min, dew point < -10degHollow Fiber Membrane Dryer
Refrigerated dryer
Dry air
DewP+16℃
7/8 7/11
-5℃
3H monitor194mBq/cc
48mBq/cc
compressor refrige
rateddryer
Hollow fiber
membrane
Water/Mist filters F He
Vessel
23
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Vessel Exhaust Line at NU3
He Vesselfilter
F Pump
Waterseparator
HEPA filter
3H monitor Spec:876ℓ/min
~470ℓ/min680m3/day
Exhaust From Vessel
Pre filter
Flow meter
Waterseparator
Sample port
To HEPA filter
3H monitor
24
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK 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.
25
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK Summary (Cont.d)
Vessel evacuation / He gas fillingOxygen 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 earthquakeDuring 2011 shutdown: Inspection by Web-camera + LEDDuring 2012 shutdown: Expansion joint was repaired, whole flexible tubes replaced.Entire system now running for Run-4 ! 26
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
Visual Inspection of DV/BD[Summer, 2011]
27
36W LED, 3,600lmilluminating angle10deg
lx
MOS sensor, min.illuminance=0.5lxX36 (18x2EX) optical zoom
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
28
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
Visual Inspection of DV/BD (2)
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Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
30
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK
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.
31
Thin Pipe was broken (~Mar.9)Due to vibration of theNewly introduced Metal bellows pump
Support and flexible tube is introducedTo absorb vibration.
Ver. 2.3 [Nov.07] NBI2012, CERN, Geneva, Switzerland, 6th – 10th November 2012
Ishida et al. J-PARC/KEK He Vessel Leak
It may be the reason of bad OTR image… 32