(4). Nonstandard Decay Total Dose Calculations.
Total radiation dose calculations for operations in areas where the decay rate is nonstandard can be
computed using the total dose (fallout) nomogram, the residual decay (fallout) nomogram, and the
correction factor for nonstandard decay (LOW n) and (HIGH n) nomograms, (Figures 6-9 and 6-10).
Total dose computations are made using the total dose nomogram and the same principles as for
standard decay with the following exceptions.
1.
The R1 value must always be determined for dose calculations using the appropriate
decay exponent. Using the residual radiation decay (fallout) nomogram, determine the H
+ 1 dose rate for the appropriate nonstandard decay exponent.
2.
For problems where it is desired to find a time of entry, time of stay so that a specific
total dose will not be exceeded, standard decay should be assumed. These calculations
will be approximations, since no direct method is available for finding these values for
nonstandard decay.
The true dose can be determined by multiplying the dose calculated from the total dose (fallout)
nomogram, by the correction factor (CRF) determined from the correction factor for nonstandard decay
nomograms in Figures 6-9 and 6-10.
6-21
CM2308
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