C. Theis, D. Forkel-Wirth, S. Roesler, H. Vincke

Outline

Ambient-dose-equivalent studies for An accident scenario (full beam-loss) Normal operation

Calculation of field calibration coefficients for the IG5 ionization chambers RAMSES monitoring system.

2C. Theis, SC/RP

Motivation Previous radiation studies by S. Roesler

et al.date back >5 years already. Minimum requirements for openings were

3m in the lower & 2m for the upper shielding.

Shielding layout has changed (new ducts, access maze, etc.)

Check compliance with radiation limit of 20 mSv ambient-dose-equivalent for a full beam loss (~ 20 mSv effective-dose)

3C. Theis, SC/RP

FLUKA geometry

C. Theis, SC/RP 4

LHCb shielding wall

Counting barracks

Entrance maze

Beam tunnel

BarrackAccess shaft PX84

Y

Z

X

2m

Entrance maze

(shown without roof)

4m

Cable tray in the floor

(1.1 x 0.17 m)3m

Side slit

for cables (0.4 x 5.6m)

Ventilation ducts

Material passageway (blocked during operation)

PAXL8501

PAXL8502

PAXL8511

PAXL8521

PAXL8512

PAXL8522

Front part of the counting barracks

Beam-loss scenario

Full loss of 1 beam

Protons at 7 TeV/c

Loss at the worst location, giving the highest particle fluence in the cavern (5m upstream from the center of the cavern)

2 - step calculations 1st step without the electromagnetic cascade 2nd step including the electromagnetic cascade

C. Theis, SC/RP 5

Beam-loss scenario

C. Theis, SC/RP 6

Beam loss point

Loss direction

Beam loss point

Loss direction

Hadrons caused by the beam-loss

:poss:poss

Beam loss point

Loss direction

Material passage is in the “shadow” at afull beam-loss

Direction of the high-energetic particles

Beam-loss scenario

C. Theis, SC/RP 7

Ground floor of the Ground floor of the barracksbarracks

Limits: (4.7 x 1014 protons)Red arrow ~ 50 mSv Blue arrow ~ 20 mSv

pSv/primary

Y

Z

PAXL8501

PAXL8502

Front part of barracks

pSv/proton

No significant impact of the cable tray in the floor

Avg. value for the front part of the barracks ~ 4mSv

Beam-loss scenario

C. Theis, SC/RP 8

22ndnd floor of the floor of the barracksbarracks

Limits: (4.7 x 1014 protons)Red arrow ~ 50 mSv Blue arrow ~ 20 mSv

Y

Z

pSv/primary

PAXL8521

PAXL8522

Front part of barracks

pSv/proton

Worst location7.24 mSv

Beam-loss scenario

C. Theis, SC/RP 9

Center of the cavernCenter of the cavernY

X

pSv/primary

Front part of barracks

pSv/proton

Limits: (4.7 x 1014 protons)Red arrow ~ 50 mSv Blue arrow ~ 20 mSvAvg. value for the front part of the barracks ~ 4mSv

Normal operation DPMJET 3 for 7 TeV proton-proton collisions

FLUKA 2006.3 for particle transport

2 step-method like for the beam-loss scenario

Normalization parameters: Luminosity L = 2 x 1032 cm-2s-1

= 80 mbarn Beam-gas interactions (104 collisions/s) were

neglectedC. Theis, SC/RP 10

107 collisions/s

Normal operation

C. Theis, SC/RP 11

Y

Z

Sv/hour

PAXL8501

PAXL8502

Front part of barracks

Sv/h

Ground floor of the Ground floor of the barracksbarracks

Limits: Blue arrow ~ 3 Sv/h

Average value for the front part of the barracks ~ 5.6 x 10-2 Sv/h ± 2%

Normal operation

C. Theis, SC/RP 12

22ndnd floor of the floor of the barracksbarracks

Limits: Blue arrow ~ 3 Sv/h

Worst location ~ 0.1 Sv/h ± 7%

Y

Z

PAXL8521

PAXL8522

Frontpart of

barracks

Sv/hourSv/h

Normal operation

C. Theis, SC/RP 13

Y

X

Sv/hour

Front part ofbarracks

Sv/hCenter of the cavernCenter of the cavern

Limits: Blue arrow ~ 3 Sv/h

Average value for the front part of the barracks ~ 5.6 x 10-2 Sv/h ± 2%

Summary & conclusions

The final shielding design was found to be compliant with the old minimum shielding requirements.

Neither the accident scenario nor the normal operation should not exceed the tolerable limits.

C. Theis, SC/RP 21