# Nuclear physics problem (Chernobyl)

Hi

I have a problem that i do not know how to solve.

Activities from the fission products I(131) and I(133) were measured in the air of a city
28/4-1986 at 17:00. The result was 0,12 Bq/m3 and 0,39Bq/m3 for I(131) and I(133), respectively. These isotopes came from the chernobyl nuclear reactor disaster.
Use this information to calculate when the reactor container exploded. The relative amount
of I(131) and I(133) produced in the fission of U(236) is 2,892 and 6,686 percent, respectively.

I would appreciate it very much if someone could solve this problem.

Astronuc
Staff Emeritus
Activity of a substance is equal to the product of the decay constant and atoms present, i.e. $A\,=\,\lambda\,N$.

At the time of release the activity ratio of I-131:I-133 has a value related to their yields from the same mass of U-236. So A(131)/A(133) is proportional to 2,892/6,686.

Simply write the Activity Ratio as a function of time from the accident and solve for the time.

halflife

how do you solve it if the halflife for I(131) is given but Halflife for I(133) is unknown?

malawi_glenn