n_ToF Target #3 - Design of N2
and moderator cooling stations
F. Dragoni - EN-CV29.05.2019
Summary
• User’s Requirements - EDMS2068190
• Technical Solution - EDMS2068336
• Integration
• Occupational H&SE
Design Review
• IEDR (15.05.2018)
• PRR - Question 13:
• Is the design and progresses on the design of the N2 cooling and moderator(s) station adapted to cope with the operational requirements of the new spallation target?
• Is there any major improvement that would need to be implemented before the tendering phase?
User’s Requirements – EDMS2068190
• 3 cooling circuits in total:
• Housed in existing CV technical room
• n+1 redundancy on chillers and moderators pumps
• HEPA and active carbon filtration on nitrogen
• Filters in dynamic confinement
• Pipework to RP monitoring chambers
Cooling
requirements Unit Target circuit
Horizontal
moderator
Vertical
moderator
Cooling media [-] Nitrogen gas –
≥99.995 %
Demineralised or
Borated Water
Demineralised or
Borated Water
Supply temperature [°C] 20 ± 2 20 ± 2 20 ± 2
Cooling power [W] 2600 200 200
Flow rate [m3/h] 780 (Nm3/h) 0.70 0.70
Maximum pressure at
equipment inlet [bar] 0.4 2.5 2.5
Technical solution: EDMS2068336
Existing moderator circuit
Chilled
water
circuit
Target N2
cooling circuit
Air extractor
Dynamic confinement extractorN2 generator
New moderator circuit
Chilled water - N2 generator - Electricity• Chilled water circuit renewal:
• 2 x 30 kW Chillers – n+1 redundancy
• Independent temperature control on each circuit
• Serves both moderators and target cooling circuits
• N2 generator
• Serviced and modified to supply up to 1 Nm3/h N2 -purity > 99.995%
• Keep cooling circuit in overpressure to avoid in-leaks and external contamination
• Power and control cubicles moved outside Controlled Area
Chilled water circuit – N2 generator: Integration
Foreseen downtime for preventive maintenance:
• Chillers – max 1 week/year;
• N2 generator – max 2 days/year;
• Electrical cubicles – max 2 days/year
Standard technology across CV (except for N2
generator)
1. Aligned with target
operational requirements
2. No technical
modifications needed
before procurement
Power and
Control cubicles
Chiller #1
Chiller #2
N2 Generator
Chilled water pipework
to heat exchangers
Nitrogen
filling line
Target N2 Cooling Circuit
• Designed to work up to 1000 Nm3/h at ∆P = 285 mbar(G)
• 4 modes of operation: (1) BEAM, (2) FLUSH (3) ACCESS (4) CLEANING
• N2 supply kept at T = 20 °C via water cooled tubular heat exchanger
• Bypass to allow for system testing – when target not installed
• Instrumentation: PT (3x); PI (3x); TT (3x); FT (1x).
(1) BEAM Mode - Blower ON
75 °C
20 °C
20 °C
30 °C30 °C
T
A
R
G
E
T
Low pressure
point: 50 mbar(G)
N2 Generator
1000 Nm3/h
Target N2 Cooling Circuit
• Circuit dilution via N2 gas flush to target area (manually actuated)
• New purge pipework to TT2 tunnel
• Finally exhaust to the atmosphere via existing TT2 tunnel extraction
• Differential pressure continuously monitor via transmitter
T
A
R
G
E
T
(2) FLUSH Mode – Blower OFFTo Tunnel
N2 Generator1 Nm3/h
Target N2 Cooling Circuit
T
A
R
G
E
T
(3) ACCESS Mode – Blower OFF
N2 Generator
Circuit kept under
inert atmosphere
(4) CLEANING Mode - Blower ON
32 °C
20 °C
20 °C
20 °C
T
A
R
G
E
T
N2 Generator
400 Nm3/h20 °C
N2 cooling station: Modelling
• 1D – Steady-state and Transient analysis of
whole cooling circuit including : blower, heat
exchanger, filter (clean/clogged)
• Study quantities at any point in the circuit
2200 rpm
Shaft speed
Flow rate
Pressure
Blower curves
Surge
2950 rpm
2950 rpm
2200 rpm System
curve
Blower: technical selection
• 22 kW motor - Magnetic motor/shaft coupling
• Pressure and leak tested at 700 mbar(G) - 2 x
Pmax - Measured leak rate: << 5 L/h
• Improve bearing selection – no need for
lubrication change every 2 years at 75 °C
outlet temperature
Characteristic curve
Magnetic coupling• Foreseen downtime for preventive
maintenance: max 2 weeks/year;
• Tests on similar model confirmed that leak
rates is well below RP threshold
1. Aligned with target
operational requirements
2. No technical
modifications needed
before procurement
Filters: technical selectionA. NUCLEAR GRADE AIR TIGHT ENCLOSURE• Fully welded Stainless Steel - Bag In/Bag Out (BIBO)
• Class 3 (EN ISO 10648) Max leak rate < 0.005 Nm3/h
• Leak tested @ 400 and 570 mbar(g)
• Max working P = + 400 mbar(g)/ -200 mbar(g)
• Pressure tested (integrity) – 570 mbar(g)
• Instrumentation: Differential Pressure Switch on each filter
B. FILTERS
• HEPA Filter - for spallation and erosion products• Supply and return lines• Efficiency > 99.98% up to 200 °C
• Active Carbon Filter – for trapping volatile compounds• Return line only• Impregnated as per RP requirements• Each carbon batch tested by external lab• Working temperature up to 80 °C
ISO 10648-2
• After installation in-situ efficiency
measurement by accredited company
Guaranteed efficiency on filters
• Filter change needs : 0.5 day
1. Aligned with target
operational requirements
2. Technical selection
confirmed
Heat exchanger: technical selection
• 30 kW Water cooled Shell and tube heat exchanger
• DN200 flanged process connections
• Max working pressure (gas side): 500 mbar (g)
• Low pressure drop: 35 mbar at 1000 Nm3/h
• Possible future option: Double tube exchanger
Chilled
water IN
Chilled
water OUT
N2 gas
IN
N2 gas
OUT
• Pressure drop monitor (Tube and Shell side)
• Virtually maintenance free
• Stainless steel construction
1. Aligned with target
operational requirements
2. Technical selection
confirmed
• Consolidation of existing skid
• New skid similar to existing one
• Instrumentation: PT/PI, TT, FT, PDT, DPT, CT, FT, FS
Moderator skids
• Retain possibility to swap borated and demi water
• Replace motor VSDs• New expansion vessel,
• New heat exchanger• New distribution pipework• New ion-exchange cartridges
• Foreseen downtime for preventive
maintenance: max 1 week/year;
• Years of operational experience from target #2
1. Aligned with target
operational requirements
2. No technical
modifications needed
before procurement
CV technical room: Integration
Moderator
skids
Blower
Heat
Exchanger
Air tight filter
casing: HEPA + AC
Controlled
Area
Sealed AreaAir tight filter
casing: HEPA
Sealed area: extraction
• Civil works designed by EN-EA
• Door for personnel access
• Roof opening for material access
• Extraction circuit independent from nitrogen purge pipe
• 90 m3/h extraction flow rate to achieve -20 Pa
• Class D ductwork that connects to existing ductwork to tunnel
• Instrumentation:
• Differential pressure switches on each filter (UBAY)
• Differential pressure between sealed area and ISR8 (UBA6)
T
U
N
N
E
L
Sealed area: filters
• INLET
• Grill with damper
• OUTLET
• F7 Filter ePM1 50-75%
• HEPA filter in airtight casing
• Efficiency > 99.98
• Working P = ±2000 Pa
T
U
N
N
E
L
RP monitoring pipework
• Monitoring via CD 10 chambers
installed next to N2 generator
• Particulate filter
• 4 couples of pipework to RP
CD10 chambers
• 1 branch before HEPA/AC filter
• 1 branch after HEPA + AC filter
• 1 branch inside CV technical room
• 1 branch on dynamic confinement
duct
Cooling station: Air Extractor
• Purpose: extract excess heat from cooling station room
• Main heat load: Blower – 5kW according to manufacturer
• Extraction flow rate
• Assuming 25 °C room temperature and extraction at 35 °C
• Minimum 1500 m3/h
Cooling station: Occupational noise
• 3 main noise sources: (1) Blower/Motor; (2) Moderator Pump/Motor;
(3) Extractor fan Combined Lp-1m = 84. dB(A)
• 85 dB(A) – 8-hour exposure limit set by European Directives/ CERN
safety code A8
• Max Lp > 80 dB(A)
Earplug dispenser,
signalisation and training
REQUIRED
• Max Lp < 85 dB(A)
Collective protective
measure (noise dampening
at walls, blower noise
attenuator) NOT required
< 84 dB(A)
70 dB(A)
54 dB(A)
Max noise
70 dB(A)
Cooling station: Oxygen Deficiency Hazard• Max N2 release volume: 2 m3 at 1.6 bar (1.35 bar – max nominal value)
• Case #1: Cooling station room
• HSE estimated a O2 concentration 20.47% > 18%
• No ODH risk in this room
• Case #2: sealed enclosure
• HSE estimated a minimum sealing area volume to avoid ODH risk: 28.4 m3
• If volume smaller
portable ODH monitor;
signalisation, leave door
open during intervention
• Current volume (not
considering occupation
factor): 33 m3 in
theory no ODH risk
Sealed
area
Cooling
station room
Future option: gas analysis
• Gas analysis system• Gas continuous analysis at pressures 100
mbar to 2 bar (abs)
• Quadruple mass spectrometer
• Soft ionisation (no spectral fragmentation)
• Mass range: 300 amu
• Detection limit: 5 ppb (triple filter)
• Multi-stream sampling(option)
• Particulate analysis• Filter upstream gas analyser
• Periodic laboratory analysis on filtered
particulate
• Chemical composition
• Particle size distribution
Hiden HPR-20 R&D
Q&A?
SCK-CEN Visit
• SCK-CEN has unique experience in studying release and filtration of
spallation products from Pb/Bi alloy. Their studies focus on Polonium (Po)
• SCK-CEN studies show:
• Polonium - Po
• Po release rate at T< 400 °C complex phenomenon dependent on
many factors (temperature, Pb oxidation, reducing atmosphere, etc)
• Volatile Po will adhere to stainless steel surface at T < 400 °C
• Active carbon filter are efficient No Po could be detected after filters
• Gadolinium – Gd
• Gd is Lanthanide Strong affinity with O2 (similar behaviour to Lu)
• Tends to forms oxides even at few ppm Solid state – NOT volatile