Radiological Safety for Experiment T-489

1. Radiological Safety for Experiment T-489 Johannes Bauer, February 28, 2007 RP-Internal Review • 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 Irradiation Experiment in Endstation A Spring 2007

2. 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 dumppulverized and liquid samples in plastic bottles close-by • Short-term samples irradiated for ~7 hoursLong-term samples irradiated for 2 to 5 days Measurement: • Dose rate and gamma spectroscopy measurements in Bldg 24 Radiation Lab (RadLab) T-489 RP-Intern Review

3. Samples at Dump T-489 RP-Intern Review

4. 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) T-489 RP-Intern Review

5. 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 T-489 RP-Intern Review

6. Long-Term Radiation (cont) 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 T-489 RP-Intern Review

7. Short-Term Radiation: Sample Change Total dose 45cm off surface: 400 mrem/h after 6 min 80 mrem/hafter 1 hour T-489 RP-Intern Review

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

9. Short-Term Radiation: Sample Change (cont) 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 T-489 RP-Intern Review

10. Short-Term Radiation: Sample Change (cont) Scenario 2: Sample exchange after 1 hour beams off: T-489 RP-Intern Review

11. Short-Term Radiation: Sample Change (cont) 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 T-489 RP-Intern Review

12. 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/hafter 10 hours (using factor 0.75 from 6 min to 12 min dose) T-489 RP-Intern Review

13. Short-Term Radiation: Air Activation – also Ozone Air Activation According to Swanson:20 pCi/cm3 at saturation, 10 pCi/cm3 after 6 min[100 W, 2 m in air, 8m x 2m x 20m] (number could use confirmation) Ozone According to NCRP #51: 0.0013 ppm after 7 days continuous irradiation while limit at 0.1 ppm (number could use confirmation) T-489 RP-Intern Review

14. 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 T-489 RP-Intern Review

15. Procedures: Radiological Postings Endstation A • ESA posted as High Radiation Area • RWP at entrance of ESA • Contamination Area inside ESA for sample transfer Building 24 • RadLab posted as High Radiation Area • Cabinet in Radiation Calibration Facility (RCF)posted as High Radiation Area T-489 RP-Intern Review

16. Procedures: Sample Exchange • At least 10 minute wait before entering ESA • 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. • Supplemental dosimeter, whole-body dosimeter, person at dump also extremities dosimeter. • Before first irradiation dump and sample wiped off. • Survey meter to ensure dose rate within the expected values. • Short time & large distance at dump, but avoid slip/trip/fall (stairs for easy access). In case of problems retreat and let dump cool. T-489 RP-Intern Review

17. Procedures: Sample Exchange (cont) • Double gloves, tweezers/nose pliers/tongs to pick up sample, drop into a lead-lined container, place new sample in (if applicable). • Processing of samples at contamination area. • Survey of samples to ensure they may be handled safely. • 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). • Transport of samples in lead-lined container, labeled “radioactive material”, use SLAC vehicle to Bldg 24. T-489 RP-Intern Review

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