Biomedical Engineering Reference
In-Depth Information
How many curies of
210
Po are needed at launch time if the
transmitter is to be supplied with 100 W of electricity 1 y
after launch?
(a)
Calculate the number of grams of
210
Po needed.
(b)
(c)
If the transmitter shuts off when the electrical power to it
falls below 1 W, how long can it be expected to operate after
launch?
(d)
What health physics precautions would you recommend
during fabrication, encapsulation, and handling of the
device?
13.
The Cassini spacecraft went into orbit about the planet, Saturn,
in July 2004, after a nearly seven-year journey from Earth.
On-board electrical systems were powered by heat from three
radioisotope thermoelectric generators, which together utilized
a total of 32.7 kg of
238
Pu, encapsulated as PuO
2
. The isotope
has a half-life of 86.4 y and emits an alpha particle with an
average energy of 5.49 MeV. The daughter
234
U has a half-life of
2.47
×
10
5
y.
(a)
Calculate the specific thermal-power generation rate of
238
Pu in W g
-1
.
(b)
How much total thermal power is generated in the
spacecraft?
A 0.2-g sample of
8
36
Kr gas, which decays into stable
8
37
Rb, is
accidentally broken and escapes inside a sealed warehouse
measuring
40 × 30 × 20
m. What is the specific activity of the
air inside?
14.
A 6.2-mg sample of
90
Sr is in secular equilibrium with its
daughter
90
Y.
(a)
15.
How many Bq of
90
Sr are present?
How many Bq of
90
Y are present?
(b)
What is the mass of
90
Y present?
(c)
What will the activity of the
90
Y be after 100 y?
(d)
A sample contains 1.0 GBq of
90
Sr and 0.62 GBq of
90
Y.
(a)
16.
What will be the total activity of the sample 10 days later?
(b)
What will be the total activity of the sample 29.12 years
later?
17.
Consider the following
β
-
nuclide decay chain with the
half-lives indicated:
-
--------
-
--------
β
β
210
82
Pb
210
83
Bi
210
84
Po.
→
22 y
→
5.0 d
A sample contains 30 MBq of
210
Pb and 15 MBq of
210
Bi at
time
t
=
0
.
Calculate the activity of
210
Bi at time
t
(a)
=
10
d.
