ORNL-4191 - the Molten Salt Energy Technologies Web Site

I
COLD LEG RETURN LIN
178
CORE OUTLET 7
PHOTO 74244
Fig. 15.2. Photograph of Partially Assembled In-Pile Convection Loop 2 Showing Design of Solt Flow Channels
in Graphite Core.
January 16, 1967, after the reactor was brought to
its full power of 30 Mw. Loop operation was
continued with solvent salt under irradiation at
temperatures ranging between 550 and 650'C.
During this period the equipment and instrumenta-
tion were calibrated and tested, loop performance
was evaluated, and reactor gamma heat was de-
termined as a function of the depth of insertion of
the loop into the beam hole. Loop operation was
during this period, and on
iF-UF, (63-27 mole %) eutec-
tic fuel (93% 235U) was added, along with addi-
tional solvent salt, resulting in a fuel composi-
tion of 7LiF-BeF,-ZrF ,-UF, of 65.26-28.7-4.84-
1.73 mole %. The nuclear heat generated in the
loop (fission plus gamma) was again determined as
a function of the dep insertion, two fuel salt
samples were removed m the loop, and on
February 21, 1967, op ion at the fully inserted,
highest flux position was achieved. Operation in
the highest flux position was continued to the end
of ORR cycle No. 71 (March 5, 1967).
The ORR was down from March 5 until March 11,
1967, for the regular between-cycle maintenance
and refueling operations. Loop operation con-
tinued throughout t period. A fuel salt sample
was removed, and, by the addition of eutectic
fuel and solvent salt, the uranium concentration
of the fuel salt in the loop was increased to the
position of 7LiF-BeF,-ZrF,-UF, of 65.4-
8-4.8-2.0 mole 76 in order to attain the experimental
objective of 200 w/cc fission-power densities
in the fuel salt. Also a sample of the cover
gas in the loop was taken for analysis.
The ORR was brought to full power of 30 Mw on
March 11, 1967. When the molten-salt loop was
placed in the fully inserted, highest flux position
on March 14, 1967, it was found that the fuel
fission-power density in the graphite core was
150 w/cc instead of the expected 200 w/cc. This
resulted from a rearrangement of the ORR fuel
between cycles 71 and 72 which caused a reduction
in thermal flux in beam hole HN-1 in an
amount sufficient to compensate for the increased
uranium in the loop fuel salt. This reduction in
flux was qualitatively confirmed by other experimenters
in an adjacent beam hole facility.
When the ORR was started up on March 11,
1967, it was observed that the radiation monitor
on a charcoal trap in the loop container sweep-gas
line read 5 mr/hr, whereas normally this monitor
read zero. We conclude
activity was caused by r
Om primary coolant wa
product leakage from the loop into the secondary
containment, and loop operation was continued.