Exhibit 19-2
The following question(s) pertain to a 450 gram sample of ⁶⁰Co recovered from a decommissioned nuclear reactor. An activity of 1.11×10¹³ Bq was measured by technicians dismantling the plant.
Refer to Exhibit 19-2. How long from the day it was removed from the plant will it take for the activity of the 450 gram sample to fall below 1 Ci? (1 Ci=3.7×10¹⁰ Bq)

Question

Quizplus · Accepted Answer

The half-life of ⁶⁰Co is 5.27 years. After 11 years, the activity will be 1.11×10¹³ Bq / 2^11/5.27 = 1.72×10¹² Bq. After 26 years, the activity will be 1.72×10¹² Bq / 2^26/5.27 = 2.69×10¹¹ Bq. After 43 years, the activity will be 2.69×10¹¹ Bq / 2^43/5.27 = 4.21×10¹⁰ Bq, which is below 1 Ci.

Exhibit 19-2 the Following Question(s) Pertain to a 450 Gram Sample of Sample