Radiation Shielding for FEE Downstream Wall (Wall 2)[email protected] RSC – FEE Wall 2 - 05/ 30/ 07 Mario Santana Leitner - Alberto Fassò Radiation Shielding for FEE

[email protected]@slac.stanford.eduRSC – FEE Wall 2 - 05/ 30/ 07Mario Santana Leitner - Alberto Fassò

Radiation Shielding for FEE Downstream Wall (Wall 2)

Alberto Fassò, Mario Santana, James Liu, Toshiya Sanami, Stan Mao and Sayed Rokni

Radiation Protection DepartmentStanford Linear Accelerator Center

RSC May 30, 2007

http://www-ssrl.slac.stanford.edu/

[email protected]@slac.stanford.eduRSC – FEE Wall 2 - 05/ 30/ 07Mario Santana Leitner - Alberto Fassò - 2 / 40 -

OUTLINEIntroduction

Layout

Scope and design goal

Strategy of the calculations

Source terms

Key components

Part I: Dose rate in NEH from cascades created in FEE by...

400 mW bremsstrahlung entering the FEE

Part II: Dose rate in NEH from...

losses in BYD1, propagated through wall 1 and wall 2.

Conclusions & Discussion



Overall LayoutOverall Layout

Undulator Hall (UH)

786 m(1/ 2 m ile)

X- Rays

Wall 1

Front End Enclosure (FEE)

Near Experimental Hall (NEH)

Beam Transport Hall (BTH)

CY38 Z = 49600 cm

BYD1 Z = 68725 cm

Personnel

Wall 2

Bfw33 Z = 64588 cm

Elect rons

Main dump



Layout of the LCLS dump line, FEE and NEH

(3’ iron + 3’ concrete)vacuum pipe openings 4” diameter

M0 Mirrors



ScopeRequest review only of the design and implementation of

the bulk shielding of Wall 2, consisting of:

3 feet of iron

3 feet of concrete

Changes may be expected for the actual design of several key components



Design goals

The main goal is to limit the dose rate in the NEH to 0.05 mrem/h (100 mrem/y)



Strategy of the calculations



Dose in NEH: Contributions and shieldingPART IA: Bremsstrahlung into FEE, normal operation

Undulator main dump hall

FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

From CX, CY...





FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

< 400 mW





FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

Wall 2 bulk

shielding





FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

Wall 2 bulk

shielding





FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

Fence?

Wall 2 bulk

shielding



Dose in NEH: Contributions and shieldingPART IB: Bremsstrahlung into FEE, C2 misaligned (dX = 10 mm)


FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

High dose around HEL

- > shielding required

Source of

radiation





FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

Hutch shutters





FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

Pipe shield AND / OR Fence



Dose in NEH: Contributions and shieldingPART IC: Bremsstrahlung into FEE, C2 misaligned (dX = 10 mm), Real wall


FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1



Dose in NEH: Contributions and shieldingPART II: Muon dose from BYD1


FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

Wall 1 bulk

shielding



Dose in NEH: Contributions and shieldingPART II: Muon dose from BYD1


FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

Wall 2 bulk

shielding

Local

Shield

Dose BYD1 < 0.005 mrem/ h



Source termsPART I (FLUKA): 400 mW of nominal bremsstrahlung spectrum into the FEE that.

produces showers in FEE, which go through Wall 2 and induce dose in the NEH.

integrates the contribution from collimators, insertion devices and (mainly) BYD.

is simulated as 1 kW of e (13.64 GeV, 37 RMS) hitting a 14 micron Ti foil.

PART II (MARS15): Radiation produced upstream of FEE and going all the

way through Wall 1 and Wall 2. For example:

Dominant: 5 W grazing the lateral walls of BYD1.

Other sources: main dump, tdund,... are negligible.

Synchrotron radiation and FEL are not an issue in this case.



Key components



Elevation view

NEHFEEBYD

PART I (FLUKA)

PART II (MARS15)

xz

y

400mWbremsstrahlung

Wall 2Z = 75640 cm

Wall 1Z = 71981 cm

Fe shadow wall (208 (H) × 97 (W) x 31 (L) cm3) with opening for beam pipe 14 (H) x 31 (W) x 31 (L) cm3



M0 and M1 mirrors: t ilted 1.44 mrad, 100 cm long, 3 cm wide, 8 cm thick

Sections of the FLUKA geometry(strongly anamorphic)

C1

M0

C2

C3

C4brem

M1

FEE

H1

H2

H3

brem

C1, C2, C3, C4: collimators M0, M1: mirrors

iron

concrete FEE

H1

horizontal plane Vertical plane

1cm ~7.7cm

W alloy

18 g/ cm 3B4C

6.15

07 cm

0.5

0 cm

Collimators



Hutch ShuttersThickness ~ 16 cm (W) to achieve attenuation from 2000 to 0.05 mrem/h

B4C protects shutter from FEL

This is a conceptual design, thermal studies need to be done

beam pipe and C3 collimator + shutters closed L = 8.25 cm

L1 = 1 cm

L = 3.25''

WB4C

x

zy zx

y



'Realistic' wall 2 with plugs, holes...

18''

< 0.2''

15''x

Z

z

y

A - A'

x

z

A A'

B

B '

16 x D= 3.81 cmbars 5/ 6 of length0.16 cm air around bars x

5''

3''

y

B - B'



Part INominal 400 mW Bremsstrahlung into FEE

A) Collimators aligned

C3

C4

C2

C1

M0

M1

B) Collimator C2 misaligned

C) Realistic wall





FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

Wall 2 bulk

shielding



Dose in NEH for 400 mW into FEEA. Normal operation

7.5E+065.0E+061.6E+065.0E+051.6E+055.0E+041.6E+045.0E+031.6E+035.0E+021.6E+025.0E+011.6E+015.0E001.6E005.0E011.6E015.0E021.6E025.0E031.6E035.0E044.6E05

NEH

0.03

0.3

NEH

z

y

In the normal configuration

(with the local shielding)

doses in the NEH are very low.

The radiation is dominated by

muons. An exclusion zone is

required in a small conical

zone around the HEL (dZ = 1.5

m, dY ~ 1 m)

[mrem/h]

0.05



Dose in NEH for 400 mW into FEEA. Normal operation


NEH

0.03

0.3

NEH

z

y

In the normal configuration

(with the local shielding)

doses in the NEH are very low.

The radiation is dominated by

muons. An exclusion zone is

required in a small conical

zone around the HEL (dZ = 1.5

m, dY ~ 1 m)

[mrem/h]

0.05





FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1

High dose around HEL

- > shielding required

Source of

radiation




NE

H

0.03

0.3

NEHNEH

Dose in NEH for 400 mW into FEE

NEH

Shutters OUT Shutters INShutters OUT Shutters OUTC2 misaligned C2 aligned

[mrem/h]

0.05 0.05




NE

H

0.03

0.3

NEHNEH

Dose in NEH for 400 mW into FEE

NEH

Shutters OUT Shutters INShutters OUT Shutters OUTC2 misaligned C2 aligned

If shutters are IN, dose in NEH is independent of alignment.

If shutters are OUT and collimators are misaligned, then

the dose in NEH increases. Mit igation will be discussed in

next RSC meeting.

[mrem/h]



Dose in NEH: Contributions and shieldingPART IC: Bremsstrahlung into FEE, C2 misaligned (dX = 10 mm), Realistic wall


FEE NEH

C1 C2 C3 C4M0 M1

Wal

l 1

Shad

owW

all

Wal

l 2BYD1 PCPM1



Solid wall Wall with plugs and gaps (filled with heavy concrete)

Total dose rate [mrem/ h] at the photon level

No visible difference in the south corner and in correspondence with the stepped plug

Effect of the holes and slits of the real wallShutters open, iron shield, C2 misaligned

z

yx


[mrem/h]



Solid wall Wall with plugs and gaps (filled with heavy concrete)

Total dose rate [mrem/ h] at the photon level

No visible difference in the south corner and in correspondence with the stepped plug

Effect of the holes and slits of the real wallShutters open, iron shield, C2 misaligned

z

yx


[mrem/h]

No major difference observed between the solid wall and

the realist ic wall.



Prompt dose in the upper floorshutters open, collimators misaligned, realistic wall

➢ Dose on the upper floor of NEH negligible despite top gap

➢ No effect of earthquake holes

[mrem/h]x

y

z


x

y

z



Part IIDose rate in NEH from

5 W electron beam continuous loss in BYD1



5W electron on BYD#1

Beam dump hall FEE NEH

< 0.0025

mrem/ h

< 0.025

mrem/ h

[mSv/ h]

[mrem/ h]

Aspect ratio 1:2

< 0.025

mrem/ h0.0025

mrem/ h

x

y

z

y

x



Conclusions



Wall 2, with 3' iron + 3' concrete is adequate (<0.05 mrem/h) if:

Beam loss in BYD1 is limited to 5 W

Insertion of devices is interlocked to 30 Hz and no high Z material is used.

1' iron shadow wall is placed after M0 (ray tracing needed to optimize design)

Small area in hutch 1 (1.5 m L – 1m W) is fenced out

Mitigation is designed for the condition of collimator misalignments and shutters out.

The design of the hutch shutters is appropriate, although thermal

calculations are required.


Documents

Radiation Shielding for FEE Downstream Wall (Wall 2)[email protected] RSC – FEE Wall 2 - 05/ 30/ 07 Mario Santana Leitner - Alberto Fassò Radiation Shielding for FEE