Review of Molten Salt Reactor Physics Calculations [Disc 2]

1
REVIEW OF MOLTEN SALT RRACTOR PHYSICS CAUXJLATIONS
1. INTRODUCTION
Q
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: This review of the physics of the Molten'Salt Breeder Reactor was
undertaken for the purpose of providing an independent,check of as'many
aspects as possible of the calculations already made. We have not attempted
any further optimization.‘, Instead we chose a design of the core
and blanket regions for which calculations had already been made, and
subjected'this design to ouranalysis. Our primary interest *as in the
breeding ratio of the equilibrium reactor.
The design we chose is essentially the one presented as the reference
case in OR,NL-~~-1467 (Ref.'l). It is a 1000 Mw(e) power , plant with
a single core, separate fissile and fertile streams, and without provision
for removal of 23%a , from the fe rtile stream.
Theprevious calculation for this design is known as Case 555 in a
series of calculations by the OPTIMNRC code.' Insofar as possible we
attempted to specify the same geometry and composition as -case 555,
resisting suggestions that this case is already obsolete, so that a
valid comparison could be made between the two calculations. For 'some
regions,.particularly for the-lower~blanket.Sind plenum,. the' specifications
for case 555 were not detailed enough for our tialculations, or
appeared to leave out 'certain-components. To fill in these gaps we
obtained additional
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layout drawings and di&ensions from the-group-work-
" -ing'on the design of the molten salt reactors.2
Our review covered six principal areas: 'cross sectioi selkction,
fission product treatment, multigroup cell calculaticxls, two-dimensional
~reactor criticality caldulations, equilibrium depletion calculations,
and start up depletion caltiulations. 'In'each area-we attempted to choose
‘methods and data which were as independent as posstble from those used
previously. However, in,a ntiber of instances we used the'ssme methods
because al*ernate computer -codes were not-available, a&for many nuclides
we used.essentially the same 'cross-section data because they seemed most
likely
to be correct,