Concept explainers
To Calculate: The shielding requirements.
Answer to Problem 10.21P
Shielding requirements are:
Explanation of Solution
Given:
Dose equivalent rate at the surface =
Assumption:
Y-90 is in equilibrium with the Sr-90. Y-90 emits 2.27MeV beta
Useful data:
Formula used:
Range of beta given by,
Zeffective is given by
Estimated bremsstrahlung production,
Beta energy converted to x-ray
Calculation:
Range of beta can be calculated by
Thickness of polyethylene required to shield the Y-90 betas can be calculated as follows:
Using the formula of polyethylene
Therefore,
Estimated bremsstrahlung production
EB is calculated as (using the average energy of betas from the Sr-Y
Therefore,
If the source is surrounded by 1.1 cm plastic, x-ray energy flux of the plastic can be calculated as,
Therefore, the dose rate is
Minimum thickness t can be calculated as,
Conclusion:
Shielding requirements are,
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