Introduction to Health Physics: Fourth Edition - Ruang Baca FMIPA UB

Evaluation of Radiation Safety Measures 715
13.22. A worker accidentally ingested an unknown amount of 60 Co activity. His body
burden was measured by whole-body counting from day 1 until day 14 after the
ingestion, with the following results:
Day 1 2 3 4 7 14
kBq 75.3 63.4 54.3 49.2 42.0 31.0
The whole-body intake retention fraction (IRF) for ingested 60 Co is given as
IRF(t) = 0.5e −1.386t + 0.3e −0.1155t + 0.1e −01155t + 0.1e −8.663×10−4 t
(a) Estimate the amount of ingested activity.
(b) What was the committed dose from the ingested radiocobalt?
13.23. A rotameter is calibrated to read directly at a temperture of 25 ◦ C and a pressure
of 760 mm Hg. It is used at an altitude of 5000 ft (1500 m), where the atmospheric
pressure is 633 mm Hg and the temperature is 15 ◦ C. What was the actual flow
rate when the rotameter reading was 2.5 L/min?
13.24. A rotameter that was calibrated for air at 25◦C and 760 mm Hg was used to
measure the flow rate of helium into a gas chromatograph in a laboratory where
the temperature and pressure were the same as at calibration. The rotameter
reading was 28.3 L/min (1 cfm). What was the actual flow rate of the helium?
13.25. The air in a laboratory with dimensions 10 m × 8m× 5 m has airborne 239Pu particles at a concentration of 0.1 DAC (DAC = 7 × 10−12 μCi/mL = 3 × 10−1 Bq/m3 ). If all the airborne activity were to settle out, what would be the areal
concentration of 239Pu on the floor, in dpm/100 cm2 ?
13.26. The continuous air monitor of a radiochemical manufacturing laboratory that
synthesizes various 14C-labeled compounds is set to alarm at 0.1 DAC. Long-term
data show that the mix of 14C in the air is 20% 14CO, DAC = 7 × 10−4 μCi/mL;
70% 14CO2, DAC = 9 × 10−5 μCi/mL; and 10% labeled compounds, DAC =
1 × 10−6 μCi/mL. At what 14C concentration should the alarm be set?
13.27. A high-volume air sampler, 10 cfm ± 1%, located at the site boundary, was activated
by a process monitor that detected an accidental release of plutonium. A
1-hour air sample that was counted 4 hours after collection in an alpha counter
that recorded 1200 counts during a 15-minute counting time. The alpha background
after a 4-hour background count was 0.2 cpm. The sample was again
counted 24 hours after the first measurement, and gave 3000 counts during a
1-hour-long counting time. Given the following information:
filter collection efficiency = 95 ± 1%,
self-absorption factor in filter = 0.5 ± 1%,
filter diameter = 10 in. (25.4 cm),
effective detector diameter = 4.5 in. (11.4 cm), and
efficiency of counting system = 30 ± 2%,