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Table 9.1. Fission Products in MSRE Pump Bowl Gas as Determined from Freeze Valve Capsules
Exp e rirrient No. FPll-42 FPll-4G FP 11-53 FP12-7 FP12-26
Sampling date 4/11/67, 02:49 4/18/67, 02:28 5/2/67, 10:43 6/2/67, 06:50 7/17/67, 06:03
Operating time, days On 65, off 1.5 hr Off 14, on 92 Off 14, on 86 On 92.3, off 42.5 Off 46, on 23
Nominal power, Mw 0 7.2 7.2 0 7.2
Re addition After 8.40 g No Nu No After 37.8 g
Features Pump off 1.2 hr Regular Neliuni bubbles Power off 42.5 days Regular
Accumulated Mvrhr 27,900 29,100 31,700 32,650 36,500
Isotope Yield Disintegrations per Minute in Total Sample
6.06
3. n
0.38
-4.7
0.35
6.2
6.2
6.35
-" 3.1
-6.0
-6.0
4.79
0.019
1.05 j< lo*1
2.52 x 10'
8.2 x lo7
1.15 x 10"
6.45 x 108
(4.4 107
5.7 x 10'
2.13 x 10'
5 9
2.31 x 10"
4.64 X 10'
9.49 10'
3.35 x 10"
7.98 x lo8
1.3 x 109
-2 x lo7
6.16 x 10'
9.81 x 10'
4.08 x io9
The considerable scatter in the data for "Zr
probably reflects scatter in the quantity of salt
mist in the sampling region and trapped in the
gas samples. The largest value (1.8 x 10' dis/
min of "Zr) was found under conditions in which
helium bubbles in the fuel were at a maximum.
If this 95Zr were present as fuel mist, it would
represent about 1.3 x g of salt per sample
or about 1.6 x 10---' g of salt per cubic centimeter
of helium in the sampling region. In all other
cases studied the 95Zr, and presumably the mist,
was two- to tenfold more dilute.
The values for 50.5-day 89Sr, which is born
from 3.2-min 89Kr, afford an opportunity to check
whether the mist shield which encloses the sampling
station permits equilibrium mixing with the
rest of the gas in the pump howl. The values for
"Sr are nearly a11 order of magnitude higher in
every case than ate those for "Zr. A sinall
9.2
1.57 x 10"
1.12 x lo1"
4.03 X 10'
1.88 x 10"
3.51 x lo9
1.05 x 1o1O
1.8 x 108
8.63 x 10'
3.72 Y, lo9
5.5 x 108
23
2.71 Y 10'l
4 ;.: 10
1.7 x 10'
4.17 x 107 3.16 x lo1",
2.17 x 6.5 x 108
2.26 x lo9> 3.52 x 109
8.64 X lo7 2.98 / 107
8.35 x 10'
4.79 x 108
4.17 10'
1.67 X 10"
3.71 x 109
1.33 x 10'
fraction of the 8gSr probably arises from salt
mist; it seems virtually certain that most of it
arises in the vapor phase through decay of the
89K~. In the three gas samples taken while
MSRE was at power, the 89Sr activity in the
samplers averaged 3.8 x 10' dis/min.
The total number of "Sr atoms per standard
cubic centimeter of gas deduced from calculating
the 89Sr counting rate back to the time of sam-
pling was, therefore, 4.7 A II the sample
as taken js assumed to represent a uniEorm mix-
ture of the pump bowl gas containing "Kr and
its daughters 89Rb and 89Sr formed since the
R9Kr left the salt, then the 89Kr was being
stripped at 2 x 10" atoms/min or at some 31%
of its production rate. If, on the other hand, it
is assumed that all the "Rb and "Sr are washed
back to the salt phase by the spray from the spray
ring, then the quantity of "Kr that must have
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