# [ RadSafe ] 1996 Question 9 Part D.3 answer

DORAN, GERARD A GDORAN at entergy.com
Thu Dec 11 09:21:47 CST 2008

```John,

Here is a quick response to your question,

I found trying to figure out the conversions in the sample problems very useful in my study for the CHP Exam.  The 51.1 is a good example of a factor I dissected to gain better understanding of the calculation.  It is a compilation of several conversions that gets the answer to rem.

You will need to use the conversion of rad to Mev/g, given on the Exam Equations, Formulae, and Constants Sheet

You will need to put the time information given in common units, uCi = 2.22 E6 disintegrations/sec, effective removal rate is in inverse days

You will need to use the form Mev/disintegration to combine with the factors above

By using unit analysis, and spending some time, you will be able to apply the conversions provided to arrive at a conversion factor of 51.1

There is another conversion on the Equations, Formulae, and Constants Sheet provided for the exam that would be a useful derivation.  It is the 73.8

D is calculated in rads

You will need to recognize C is to be used in uCi/g

And that the formula form uses T ½ instead of 1/lambda, this requires a factor of 1.443 (inverse of 0.693), that when multiplied by 51.1 gets you to 73.8

I spent hours on this stuff, this is how you prepare - keep it up, you are on the right path

Gerry Doran, CHP

Arkansas Nuclear One

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