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

6
2. I Fuel Circuit
The fuel circuit for a DNSR would be very similar to that for an
f.1SBR; only the core design would be changed. The primary requirement
for this redesign
density) to
a realaction in the core neutron faux (ana power
1. extend the life expectancy of the graphite moderator to the full 30-
2.
year plant %ifetLaae,
limit neutron captures in 233~a which, to enhance pro~~feration re-
sistance, would be retained in the fuel salt.
me lower power density would also tend to reduce the poisoning effects
of short-lived fission products and to simplify the thermal-hydraulic con-
straints on the design of the moderator elements, The principal unfavor-
able effects would be the increases in inventory of the fuel salt and fis-
sile fuel. Reference-design features of the DNSR core are described in
greater detail in a later section.
At design power (h000 MWe), the fuel salt, which would have a liqui-
*
dug temperature of about 5OO"c, would enter the core at 566"~ and leave
at 704'C to transport about 2250 PlWt (in four parallel loops) to the sec-
ondary salt, The flow rate of salt in each ~f the primary loops (includ-
ing the bypass for xenon stripping) be a ~ ~ I u&/s t (a6,o00 gpm>.
IFfme primary salt would ~~ntain 0.5 to 1% (by volume) helium bubbles to
serve as a strip ing agent for xenon and other volatile fission products,
Helim WQUI~ be added to and removed from bypass flows of -10% of each
of the primary hoop flowse This gas stripping would also remove some of
the tritium from the primary salt,t partly as ~HF; p~owever, nost of the
tritium would diffuse through the tube walls of the primary heat exchang-
ers into the secondary salt. Helium reraoved from the primary circuit
would be treated in a series of fission-product trapping and cleanup steps
before being recycled for further gas stripping. P~-ovisions would alls~ be
cooling 0
* %he temperature at which the first crystals appear on equilibrium
P~stimates are that 18 to 19% 0% the total tritiw produced wml~l
removed in this gas,
be