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

t.;$- ... quite different from those of the present EWR and liquid-metal fast
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breeder reactor QLMFBR) designs. A detailed safety analysis of the DMSK
must await the results of a research and development CUD,> program; how-
ever, identifying possible generic problem areas and some of the advan-
tages and disadvantages of this concept is already possible.
In the DMSW, the primary system fluid serves the dual role of bein
the medim in which heat is generated within the reactor core and the me-
dium that transfers heat from the core to the primary heat exchangers.
Thus, the entire primary system will be subject to both high temperatures
(900°C at the core exit) and high levels of radiation by a fluid contain-
ing most of the daughter products of the fission process. Because of the
low fuel-salt vapor pressures however, the primary system design pressure
W i l l b@ IOW, -3s in an LMPBRe %XI t@KUIS Of level Of ConfinelTlent, the entire
reactor primary systen is analogous to the fuel claddi in a s~%id-fuel
reactor. Although much larger, it will not be subject to the rapid ther-
mal transients (with melting) associated with LWR and LMFBR accident see-
narios. Two additional levels of confinement will be provided in the
BMSW, in accord with present p~aetice, Note that the once-through DMSR
concept has safety advantages QV~P the break-even DMSR because a large
and complex part of the primary containment - the chemical reprocessing
plant - is substantially reduced and because less radioactive material is
routinely removed from containment. The problem of developing a reactor
primary system that will be reliable, maintainable (under remote condi-
tions), inspectable, and structurally sound over the plant's SO-year life-
time will probably be the key factor in demonstrating ultimate safety and
Iicensabil fty .
The breach of the reactor primary system b~~daryv, resulting in a
spill of highly radioactive salt into the primary containment, will prob-
ably provide the design-basis accident,
The analogous event in a solid-
fuel reactor would be major cladding failure. Possible initiators o% this
accidemt include pipe failure, missiles, and pressure or temperature tran-
sients in the primary salt system. Failure of the boundary between the
prhary and secondary salt in the primary heat exchangers could be espe-
cially damaging. In the event of salt spill, a possibly redundant sys-
tem of drains would be activated to channel the salt t o the continuously