The composite neut
capture decay curve will then be the sum
of the decay curves of vest, eo, Np239, u240, and Np240 , 1.@.,
Ae = Ago (02000416270 200431t 4 -1.77t
(3.9)
F 0.00652—70sOL24t 4 0.014600 00495t yx
where A, = Activity due to capture products at time t and
Agoz Proportionality constant
Aco can be determined from the ratio of neutron capture to
fission activity measurements.
1239 9
TABIE 3.1 ~ Initial
tive Ac
ties of 237
U
’ v
Np239, By) » and Ngee
The Shot 1 decay curve will then be the sum of Eqe 304
and Eqe 3e92
The experimentally determined ratio of uranium capture
products to fission products can then be used to find the value of
Aco if it is remembered that Ayr has already been determined.
A,|250
Ay¢ (250) ~
= 0.8
(3.10)
068 Ayp(250)“H a Ag (Ecye 4")
(3.11)
The curve was then normalized (set eoual to 1) to 400 hours, at which
time the activity data were knowne
The equation for the extrapolation of fission and neutron
induced activities to sampling time is then
A = 1350 7226 4 2200(0,000z16e70-00431t (3-12)
f en~Le77t40 0065207020124bto 0146070 00495t )
This composite curve is showm in Fige 3ele
*
The last term includes the activity of both U
39
240
and No
240