ORNL-TM-7207 - the Molten Salt Energy Technologies Web Site

22
The fit to data representing four E-~KWV~E times from five years to infin-
ity had an absolute standard deviation of 6.28%, which was considered
adequate. Studies using this model indicated that removal times of a few
years but shorter than infinity were not worthwhile, and the results of
this section assume R = 0.
3-1 e 4.3 Trans~lutonium ef f ects
A detailed study of transplutonium effects9 was made, and the con-
chsion was reached that the resulting fissile production only partially
offsets the capture. The balance is less favorable than in reactors of
higher power density because of the partial ~ ~ecay of 244~1~ to 2 4 0 which ~ ~ ~
has comparatively less value.
produced from 23%~ is joined by 0.11 additional atoms from the decay of
244~me
plutonium effect, 4.0 additional absosptio~~s and 3.2 additional. fission
neutrons ultimately result.
me study showed that each atom of 2 4 0 ~ ~
FOP each neutr~n absorption in 242~u ca~culated without the trans-
Although the actual time effects are complicated, the net effect was
approximately represented as an additional fictitious ~uclide, which was
produced by capture in 2‘’~u and had the absorption cross section of 242~u
and no progeny. This would be slightly conservative at equilibrium and
probably at earlier times also.
3. E. 5 Static neutronic results
Table 9 indicates the inventory of actinides at the beginning, mid-
dle, and end of the 30-year operating period, assuming a 752 capacity fac-
tor. The high initial loading of 235U is largely replaced by 233U bred by
the system in the first half of the lifetime. Toward the end of lifetime,
enriched uranium additions required to override fission-product buildup
cause a final increase in both the 23% and 238U content. The plutonium
inventory is never Barge because of its high cross section in this spec-
trum.
Table 10 shows the midlife neutron utilization infomation. Yste the
low capture rate in nonfuel salt constitu@nts (O.Ol53) and the fission-