Review of Molten Salt Reactor Physics Calculations [Disc 2]

11
7 Li at this price.' More recently it has been concluded by those working
'on molten salt reactor design that it would be reasonable to asimme that
99.995% 7Li could be obtained in large quantities at $126 per kg.2 We
have foliowed this.latter assumption and used 99.995$ 7Li in our calculations,
leading to a decrease in breeding ratio of 0.002.
the ,previous calculations neglected the production of 6 In addition,
Li in the core
from n,(T reactions in beryllium.
I
This source of 'Li gave an additional
0.003 decrease in breeding ratio.
10. We obtained a loq& higherneutron production from the De(n, 2n)
reaction than in the previous calculations. The difference, came fromour
taking into account the heterogeneity of the cell in the.hlgh-energy
range. The effect on breeding ratio was an increase of about 0.001.
Although our calculations gave a net increase in breeding,ratio-of
almost Q.Ol~compared to the previous ones, it should be Inept in mind
that this increase in breeding ratio was accompanied by-an increase in
fissile inventory. Indeed, the,iacrease in breeding ratio is about what
one would expect from the change in fissile,inventory alone, so that
other increases.and decreases have aDproximately.cancel&ed. A subsequent
re-optimization would probably lead to a somewhat lowerbreeding ratio
and lower inventory.'
Table 2.3 shows a comparison of the two sets of calculations with
respect to spatial distribution of neutron.absorptions, There is ~generally
good agreement. However, the. mow valuesof *leakage obtained in our ca+
culations raise a questionas to whether .the blankets are thicker Ihan
optimum.
Table 2.3 MSBR Absorption Distribution
Comparison
x
u 4
Present
Calculation
Previous
.Calculation
Core .
&0305 2.0325
;Radial blanket
o.i458
Axial blanket
0.0451 :*z I
Radial leakage plus structure 0.0012 0.001g
Axial leakage plus structure 0.0002 0.0001
Delayed neutrons lost . 0.OOg1 0.0050
Total 3
.2.2279 ,2.2211
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