Radiological Safety for Experiment T-489 Irradiation Experiment in Endstation A Spring 2007 ITEMS: Experimental Setup Long-Term Radiation inside ESA Short-Term Radiation at Sample Change Short-Term Radiation from Sample Handling Training Requirements Procedures Thanks to Stefan Roesler for all plots and dose estimates Johannes Bauer, February 28, 2007 RP-Internal Review

2/28/2007T-489 RP-Intern Review2 Experimental Setup Irradiation in Endstation A (ESA) Beams: 28.5 GeV at 100 W, 1 to 10 Hz Copper dump 4” diameter, 10” long Samples surrounding dump: solid samples in aluminum holder sitting on dump pulverized and liquid samples in plastic bottles close-by Short-term samples irradiated for ~7 hours Long-term samples irradiated for 2 to 5 days Measurement: Dose rate and gamma spectroscopy measurements in Bldg 24 Radiation Lab (RadLab)

2/28/2007T-489 RP-Intern Review3 Samples at Dump

2/28/2007T-489 RP-Intern Review4 Long-Term Radiation Concrete in ESA Already irradiated: concrete below dump location 0.6 mrem/h on contact, general area has 0.25 mrem/h Experiment adds not much: After 100 hours dose rate from wall is < 0.05 mrem/h (dose rate uniform: 50 cm distance from beamline = same as contact with wall)

2/28/2007T-489 RP-Intern Review5 Long-Term Radiation (cont) Equipment in ESA Wire scanner ~2 m upstream, beam monitor ~2 m downstream After 100 hours dose rate: up to 0.63 mrem/h Suggestion: install something (old dump?) downstream

2/28/2007T-489 RP-Intern Review6 Dump After 100 hours: 1.5 mrem/h at 45cm distance 65 mrem/h on contact Dose rate of dump will also be part of experiment Long-Term Radiation (cont)

2/28/2007T-489 RP-Intern Review7 Total dose 45cm off surface: 400 mrem/h after 6 min 80 mrem/h after 1 hour Short-Term Radiation: Sample Change

2/28/2007T-489 RP-Intern Review8 Dump 45cm off surface: 400 mrem/h after 6 min 80 mrem/h after 1 hour On dump surface: 13 rem/h after 6 min 2.8 rem/h after 1 hour Short-Term Radiation: Sample Change (cont)

2/28/2007T-489 RP-Intern Review9 Scenario 1: Sample exchange after 12 min beams off: 400 mrem/h after 6 min  dose after 12 min lower by 0.75 = 300 mrem/h TASKDOSE RATETIMEDOSE Approach1 mrem/h1 min0.017 mrem Sample change cm 20 sec (1min)1.7 (5) mrem Retreat1 mrem/h1 min0.017 mrem Total 1 change1.7 (5) mrem Total 20 changes34 (100) mrem Short-Term Radiation: Sample Change (cont)

2/28/2007T-489 RP-Intern Review10 Scenario 2: Sample exchange after 1 hour beams off: TASKDOSE RATETIMEDOSE Approach1 mrem/h1 min0.017 mrem Sample change80 45 cm 20 sec (1min)0.4 (1.3) mrem Retreat1 mrem/h1 min0.017 mrem Total 1 change0.5 (1.4) mrem Total 20 changes10 (27) mrem Short-Term Radiation: Sample Change (cont)

2/28/2007T-489 RP-Intern Review11 Comments: Assumed dose rate for 4 days continuous beam = true only for end of experiment At end of experiment only sample retrieval Hands might get closer than body, but tongs will be used Use of tongs will be rehearsed; if problems arise will wait longer to retrieve samples At least five people to take turns Really worst case: if initially 10 mrem/h per sample exchange, then 20 mrem/h (after 10 min wait): total dose for 20 exchanges 300 mrem Short-Term Radiation: Sample Change (cont)

2/28/2007T-489 RP-Intern Review12 Short-Term Radiation: Sample Handling Old dump numbers: 50cm away: 0.23 mrem/h after 12 min 0.03 mrem/h after 10 hours On contact: 230 mrem/h after 12 min 20 mrem/h after 10 hours (using factor 0.75 from 6 min to 12 min dose)

2/28/2007T-489 RP-Intern Review13 Short-Term Radiation: Air Activation – also Ozone Air Activation According to Swanson: 20 pCi/cm 3 at saturation, 10 pCi/cm 3 after 6 min [100 W, 2 m in air, 8m x 2m x 20m] (number could use confirmation) Ozone According to NCRP #51: ppm after 7 days continuous irradiation while limit at 0.1 ppm (number could use confirmation)

2/28/2007T-489 RP-Intern Review14 Training Requirements Every Experimenter #219: EOESH #239: General Electrical Safety #115: GERT #116: RWT-I + practical #250: RWT-II + practical Some at SLAC (JB,JL,AF?) Limited Radiological Controls Assistant Experiment-Specific Training Extensive safety briefing and rehearsal for exchanging and handling samples

2/28/2007T-489 RP-Intern Review15 Procedures: Radiological Postings Endstation A 1.ESA posted as High Radiation Area 2.RWP at entrance of ESA 3.Contamination Area inside ESA for sample transfer Building 24 1.RadLab posted as High Radiation Area 2.Cabinet in Radiation Calibration Facility (RCF) posted as High Radiation Area

2/28/2007T-489 RP-Intern Review16 Procedures: Sample Exchange 1.At least 10 minute wait before entering ESA 2.One experimenters is LRCA, one in charge of radiation safety. Initial & intermittent support by RPFO. Sample exchange by one person alone o.k., two people preferred. 3.Supplemental dosimeter, whole-body dosimeter, person at dump also extremities dosimeter. 4.Before first irradiation dump and sample wiped off. 5.Survey meter to ensure dose rate within the expected values. 6.Short time & large distance at dump, but avoid slip/trip/fall (stairs for easy access). In case of problems retreat and let dump cool.

2/28/2007T-489 RP-Intern Review17 Procedures: Sample Exchange (cont) 7.Double gloves, tweezers/nose pliers/tongs to pick up sample, drop into a lead-lined container, place new sample in (if applicable). 8.Processing of samples at contamination area. 9.Survey of samples to ensure they may be handled safely. 10.Solid samples: use tools to wipe for contamination. If contaminated, place into plastic boxes. Pulverized and liquid samples: pour into fresh bottle (funnel, on disposable surface). 11.Transport of samples in lead-lined container, labeled “radioactive material”, use SLAC vehicle to Bldg 24.

2/28/2007T-489 RP-Intern Review18 Procedures: Measurements 1.Supplemental dosimeter, whole-body dosimeter; also extremities dosimeter for samples with > 300mR/h. 2.Double gloves as long as contamination possible (always for soil and concrete). 3.Tongs or pliers used as long as sample dose rate high 4.Storage of samples inside RCF; transport between RadLab and RCF inside lead-lined container The End