4th International Workshop on Neutrino Beams and Instrumentation(NBI’03)

Beam Dump Design for
J-PARC Neutrino Project

In collaboration with
A.K.Ichikawa, T.Ishida*, J.Kameda
T.Kobayashi, M.Sakuda, Y.Oyama, & Y.Yamada (KEK IPNS)
J-PARCν construction group

1. Requirements
2. MARS Simulation for Beam Dump
3. Beam Dump Cooling
4. Layout of Beam Dump & Muon Pit
5. Summary & Schedule
2003/12/3

NBI03, KEK, November 7~11th, 2003

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1. Requirements for BD/MUPIT• Radiation shielding at operation< 11mSv/h at the edge of shield (Outer Concrete – Soil)• Residual dose rate in the muon pit< 12.5μSv/h for the normal controlled area.

• Beam dump cooling~¼ of total heat is deposited in the Beam Dump.

• Radiation in cooling water
H.E.γ(16N,14O), delayed neutron emission(17N): coolingsystem should also be shielded and be in underground.
3H production: We are planning to dispose it (<15Bq/cc)
by dilution. Hadron fluence at cooling place should beenough low = Cooling path should be as far as possible
from beam center.

• RedundancyCore part is highly radio-active so it is hard to access.
Need to bear 20 years, also for 4MW operation.
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Decay Volume, Beam Dump and MUPIT

An updated design
will be shown later

110m
2003/12/3

NBI03, KEK, November 7~11th, 2003

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2. MARS Simulation for Beam Dump
• Φ- symmetrical geometry with iron + concrete
Δr=10/5cm, Δz=20/5cm, corresponding to OAB 2°• Calculate incoming particle flux, energy deposit,
hadron fluence, and dose equivalent of each volumeand obtain critical boarder lines for BD design:
Energy Deposit= 0.02Joule/cm3=5,000W/m3= DV plate coil, boarder between Iron and Concrete.
Hadron Fluence = 1×10-5 (2×10-6) /cm2/proton
at cooling path for 750kW (4MW) operation
Dose Equivalent =11mSv / hour / (factor), wherefactor = “Threshold factor” (2)×[Safety(2)]Former comes if we set neutron energy cutoff threshold(10-3eV→20MeV) in the simulation to save CPU time.
For 4MW operation, latter is taken into account already inthe design value
2003/12/3

NBI03, KEK, November 7~11th, 20034

Φ- symmetrical Geometry• Beam: Δx,y=0.424cm / ΔΘx,y=0.5mrad• HORN Magnetic Field ON/OFF• MUON Production ON/OFF
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NBI03, KEK, November 7~11th, 2003

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Results: Incoming Particle Flux(1)HORN ONOFF/ 100,000 p.o.t.

2003/12/3

NBI03, KEK, November 7~11th, 2003

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Results: Incoming Particle Flux(2)/ 100,000 p.o.t.

Protons w/o interaction at target (~17%, σx,y= 15cm)

2003/12/3

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Results: Energy Deposit and Hadron Fluence
Concrete

BD Fe
16 J/cm3, +4.6℃/spill

0.02J/cm3(Fe-Concrete)

Fe ~1.5m

DV He~2.5m~2.5m

MUON2e-6 /cm2/P(Cooling Water Path)

~1.7m
~1.7m

2003/12/3~2.5m~2.5m NBI03, KEK, November 7~11th, 2003

8Results: Energy Deposit with/without Muon Production

BD FeDV He

Concrete

Possible MUPIT location: Fe 3.5m equivalent
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NBI03, KEK, November 7~11th, 2003

9Results: Dose Equivalent
Concrete
BD Fe
Fe ~1.5m

100 Sv/h(Fe-Concrete)

11mSv/h(Concrete-Soil)

DV He

Iron 4m +Concrete 1.5m

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NBI03, KEK, November 7~11th, 2003

103. Beam Dump Cooling• Compared to K2K, JPARCν project employs ×150
intense beam. An efficient cooling is necessary.
Ep(GeV)Power(kW)BD loss(kW)125~1830

5Air Cooling

CNGS

400

300

30

Graphite+
Al Module

NuMI

120

410

60

Al+Fe coremodules

JHF-SK

50750

190

SJHF-HK

50

4,000

1,000

Super-beamfacilities(K2K)

Cooling
Scheme(none)• Choice of core material
Input: MARS simulation energy deposit, scaled bymaterial density.
Check temperature distribution both by static calculation
and by transient heat simulation by NASTRAN code.
2003/12/3

NBI03, KEK, November 7~11th, 2003

11Temperature distribution at Equilibrium
Ex. Core material: Cu(λ=400W/m・K)
4MW

750kW
Q( r)

100

T(r )-TR600
300α(Δt=50℃)
500

2000
1.5m

T(r=0)-T(1.5m)=125℃
α(1.5m)=600W/m2K

1.5m

T(r=0)-T(60cm)=300℃
α(60cm)=4kW/m2K

T(r=0)~125+50+30=200℃
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Comparison ofCore Material Candidates

Iron
Graphite
Aluminium
CopperDensity(g/cm3)

Max.Dep
Max.Dep(J/cm3)750kW

Core
Length(m)Conduc
tivity(W/mK)(W/mK)

7.8

3.2

2.075

1.8
2.7
8.9

0.8
1.2
3.8

6.5
5.0
1.5~150

In case ofCooling at r=1.5mMax
Temp
750kW
(4MW)

750kW
(4MW)

1,535 +660℃

600(3,800)

(3k)

+85℃

140(440)

(700)

+80℃

200(420)(1.1k)

Melting
Temp.
(℃)>3,500

240
400

660

1,085 +155℃
(820)

α

W/m2K

700
(3.5k)• Higher density = higher local energy deposit= smaller core size☺ = smaller amount of water☺
• Cu has the highest heat conductivity.
= further cooling water path
= lower hadron fluence at cooling surface☺
2003/12/3

NBI03, KEK, November 7~11th, 2003

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Cooled withConv. Coef.
=600W/m２・K

Transient heat analysis (NASTRAN)
Max.
Copper
750kW

147℃

Iron
750kW

849

Copper
4MW

748℃

Iron
4MW

4,490

Consistent to theanalytic calc.
750kW is OK with
Copper core.
Need measurefor 4MW.
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Cooling Water and Its Treatment(rough estimation)
What we need:
2×1.5×π×1.5=14.1m2, × α=700W/m2K

1.5mm
1.5

Cool core by 1inchφ×20 pathes

1.5m
1.5m

750kW×1/4×1/20 = 9.4kW/path
Total amount of water in tubes = 13 litter
Water flow rate = 30litter/min = 1.16m/s⇒ ΔTwater=4.5℃, α=4.9kW/m2K
Inner surface area in total = 2.2m2⇒ 2.2×4.9 ~ 14.1×0.7

Water system:
A circulation path with heat exchanger+ a dilution path.
The dilution path= a deposit tank + a dilution tankto dispose water with < 15Bq/cc.
BD: 2.6m3 when diluted to 15Bq/cc equivalent.

Details was presented in “Radiation Safety Issues”
2003/12/3

NBI03, KEK, November 7~11th, 2003

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4. Layout of Beam Dump and Muon Pit
Coolingpath

CoreCu 230t

Mu
Pit

Iron block
660t(DURATEC?)

Cooling pit(Heat Exchange)

2003/12/3

Dose Equivalent~100(40) mSv/h
Residual Dose (30d/1d)
0.2(0.05) uSv/h
NBI03, KEK, November 7~11th, 2003

Temp. raise
Air: +1℃/1.2h
Conc:+1℃/1.8h(Air conditioned)16

Hadron Fluence
2e-6 /cm2/P(Cooling Water Path)

11mSv/h

DOSE Eq.

(Concrete-Soil)

100 Sv/h(Fe-Concrete)

2003/12/3

NBI03, KEK, November 7~11th, 2003

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5. Summary• A possible BD/MUPIT design is shown.
Materials to MUPIT: Eμ>4.5GeV
Copper core(1.5m)+Iron block(1.5m)+Concrete(0.5m)
Hadron Fluence / residual dose at MUPIT is low enough.
Hadron fluence at cooling path around core is equal to orless than that of DV plate coil, to dispose it with < ×200dilution.
Convection coef.=700W/m2・K for 750kW operation isenough realistic.
• Detailed BD core design is under progress.
Need measure for 4MW operation. This can be achieved
with a cooling path at around r=60cm.
Requirements for muon profile monitor settled after BD (J.Kameda)
Good sensitivity for magnet and proton beam position with 2~5 GeV/cthreshold and no big difference in this region.
Above ~ 7 GeV/c, the sensitivity become worse.
With 5GeV/c threshold, muon fluence is ~108/spill/cm2.
Possible design is under discussion with physics group.
2003/12/3

NBI03, KEK, November 7~11th, 2003

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Schedule
FY2003

2004

2005

2006

2007

2008

Conceptual design
Technical design
07/31
Civil construction
CoreProduction

Installation

ImportInstallation

Iron block
Water system

Installation

K2K

2003/12/3NBI03, KEK, November 7~11th, 200319