T-489: Induced Activity and Residual Dose Rates

Irradiation Experiment in Endstation A Spring 2007

Johannes Bauerfor T-489 experimenters

prepared 3/19/2007

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Motivation

Monte Carlo Simulations for Design of New Facilities• Simulation of residual activity improved in last years• Better-controlled experiments needed for benchmark

tests

CERN Involvement: • Four collaborators from CERN• Two years ago similar experiment at CERN with hadron

beam• SLAC experiment complimentary with electron beam

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Experimental Setup

Beam • Primary beam 28.5 GeV at 20 W average (up to 100 W

temporarily), ~ 2x109 e-/pulse at 1 to 10 Hz (not exceeding 100 W)

• Compatible with PEP2 and BABAR• Beams delivered to dedicated copper dump • Need to know absolute beam power to ~5%

Equipment

• Use of existing wire scanner 3WS1 and standard roller screens for beam monitoring and alignment

• Use of existing toroids to measure current

Infrastructure• Just standard beam delivery

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Samples at DumpInstallation in beam line inside shielding tunnelof ESA

Regularly controlledaccess to remove and replace samples

Measurements of samples in Bldg.24

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Schedule

Installation Official schedule: Mon/Tue April 2/3, 2007

(earlier if access to ESA possible)

Beam Starting Wed April 4, 2007 for 5 to 7 days

(earlier if beams available)

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Radiation Hazards

Concrete in ESAAlready irradiated

T-489 does not add much: < 0.01 mrem/h

Equipment in ESAAlso very little: ~ 0.13 mrem/h

Dump

1 mrem/h at 30 cm distance off dump surface13 mrem/h on contact

Values for 100 hours cooling time

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Radiation Hazards (cont)

Worst case radiation dose according to simulation, 4 days, 20 W, 15 min cooling time:

contact 30 cm

Dump 2000 mrem/h

130 mrem/h

sample(worst case stainless steel )

2 mrem/h 0.02 mrem/h

Dump’s 30 cm dose rate: 70 mrem/h after 30 min cooling time 50 mrem/h after 1 hour cooling time 20 mrem/h after 10 hours cooling time

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Radiation Hazards (cont)

Exposure during sample exchange (4 days of 20 W, 15 min cool-down):

Task Dose rate Time Dose

Approaching dump

1 mrem/h 1 minute 0.017 mrem

Exchanging sample

130 mrem/h

20 seconds

0.72 mrem

Leaving dump 1 mrem/h 1 minutes

0.017 mrem

Total 0.76 mremTraining and rehearsals will be required

Radiological postings and procedures worked out with RPFO

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Conclusion

Radiological aspects under controlboth short-term and long-term

No additional safety hazards (e.g. no earthquake bracing needed for equipment)