Step 1.
Separate the two contributing dose rates.
An examination of the measured dose rates indicates that the fallout from the first burst peaked
prior to H + 1 hour (0900). The reference dose rate (R1x) for this portion of the fallout would be
100 cGyph. The fallout from the second burst peaked prior to H + 1 hour for the second burst
(1200); thus the reference dose rate (R1y) for this portion would be 219 cGyph minus the
contribution from the first burst. Using the procedure for determination of n from a single burst,
calculate the decay exponent nx for the first contributor.
T1x and R1x represent the time after burst and dose rate at H + 1 of the first burst (nx). T3x and
R3x represent the time after burst and dose rate of the last reading taken before the pattern is
influenced by the second burst. The symbols used in the equation for the second burst (ny)
represent the H + 1 and last reading values for that burst.
Then R4x (1200) would be 19 cGyph as determined from Figure 6-5 on page 6-11. Therefore, R1y, the
reference dose rate for the second contributor, would be 219 - 19 = 200 cGyph. Calculate the decay
exponent (ny) for the second contributor.
Step 2.
Calculate the total dose rate.
Calculate the total dose rate for 0800 hours 24 hours after the first burst by finding the dose rate
for that specific time for each contributor separately; then add the two values. Use Figure 6-5 on
page 6-11.
CM2308
6-16
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