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

Evaluation of Radiation Safety Measures 711
13.5. The maximum permissible skeletal burden of 90Sr is 74 kBq (2 μCi). Calculate
the number of transformations per minute per 24-hour urine sample that may be
expected from one-fourth of this skeletal burden if 0.05% per day is eliminated
in the urine.
13.6. Using the ICRP three-compartment lung model and the data for the reference
man, calculate the ratio of concentration of soluble 1-μm AMAD uranium particulates
in the air to uranium in the urine, Bq/m3 air per Bq/L urine, for the
case where a steady state has been attained through continuous inhalation of the
uranium.
13.7. The body burden of 137Cs at time t days following a single intake Q(0) is given
by
Q(t) = Q(0) × (0.1 e −0.693t + 0.9 e −0.011t ).
If the ratio of urinary to fecal excretion is 9 : 1, calculate the activity per 24-hour
urine sample 1 day and 10 days after ingestion of 50,000 Bq (1.35 μCi) 137Cs. 13.8. A chemist accidentally inhaled a 14C-tagged organic solvent that is readily absorbed
from the lungs. The solvent is known to concentrate in the liver. That
part of the solvent which is eliminated before deposition in the liver leaves in the
urine; the detoxification products are eliminated from the liver into the GI tract
and into the urinary tract; 25% is eliminated in the urine and 75% in the feces.
Following the inhalation, 24-hour urine samples were collected over a 2-week
period and the following data were obtained:
Days after inhalation 1 2 3 4 5 6 8 10 12 14
kBq/Sample 98 57 39 26 20 18 12 10 7.4 5.9
(a) How much activity was absorbed into the body?
(b) What was the total dose to the body during the 13 weeks after inhalation?
(c) What was the total dose to the liver during the 13 weeks after inhalation?
(d) What was the effective committed dose equivalent?
13.9. A health physicist samples waste water to ascertain that the water may be safely
discharged into the environment. The water analysis is made by chemically separating
the 90Sr, allowing the 90Y daughter to accumulate, then extracting and
counting the 90Y activity. The volume of the sample was 1 L, the 90Y in growth
time was 7 days, and the 90Y activity was determined 15 hours after extraction
in an internal gas-flow counter having an overall efficiency of 50%. The background
counting rate, determined by a 60-minute count, was 35 cpm. The sample
(including background) gave 2766 counts in 60 minutes. What was the 90Sr concentration, at the 90% confidence level?
13.10. An air sample that was counted 4 h after collection gave 1450 counts in 10 minutes.
The background was counted for 30 minutes, and gave a rate of 45 cpm.
The sample was counted again 20 hours later, and gave 990 counts in 10 minutes;