Molten-Salt Reactor Program Semiannual Progress Report, January 31, 1964 Page: V

                                
Two prototype cooling bayonets, constructed of INOR-8, were operated
through 180 rapid-quench cycles (1350 to 212"F), a total of 3400 hr.
Both tubes were free of cracks, but one was badly warped, probably be-
cause the method of operation produced more temperature cycles in that
tube. Testing was continued.
A freeze valve, designed for operation where the valve must open on
a power failure, was tested and found satisfactory. The average melt
time was 10 min, and the average freeze time was 20 min.
Testing of a prototype of the reactor drain valve was started, and
preliminary indications were that the freeze time would be 20 to 25 min.
The melt times averaged 5-1/2 min with power and 13 min under a simulated
power failure. Testing was continued to determine whether the freeze
time can be reduced.
The prototype control-rod-drive unit was operated under MRE condi-
tions through a total of 40,000 full-stroke cycles. Minor modifications
were made to strengthen the rib cage, to improve alignment, and to in-
crease the shock-absorber stroke. Excessive wear on an aluminum-bronze
worm wheel in the gear reduction unit caused the drive to require repair
after 17,438 cycles. Other materials are being considered for the worm
wheel and will be tested. Measurements on a new, flexible control rod
indicated that 95% of the permanent elongation occurred during the first
week of operation and that prerunning new rods at temperature would allow
them to stretch to the final operating length. Operation of a dynamic
brake to reduce rod overtravel and of the synchro system for remote posi-
tion indication were both satisfactory. The magnetic-clutch release time
was measured as less than 25 msec, and the acceleration of the falling
rod was 13 ft/sec2. These values are satisfactory.
The oxygen-removal unit was operated at 1160F with a helium flow of
10 liters/min (STP) and an inlet oxygen concentration of 225 ppm until
the concentration of oxygen at the outlet exceeded 0.1 ppm. This period
was the equivalent of about one year of operation under the MSRE require-
ments, and approximately 58% of the titanium bed was consumed. A black
deposit, found by others using similar equipment, was identified as a
carbonaceous material originating from an organic solvent used in clean-
ing the components.
The Engineering Test Loop (ETL) was operated for 4400 hr for testing
the sampler-enricher mockup and for following the inventory of uranium in
the loop. A comparison of the uranium concentration by chemical analysis
with the calculated uranium concentration indicated a discrepancy of 9%.
Efforts to resolve the discrepancy are continuing.
Thirty-five salt samples were removed, and eleven capsules of enrich-
ing salt were added with the sampler-enricher mockup. The sample capsule
was modified to reduce the tendency to bind and to strengthen the connect-
ors. A 6-3/8-in.-long enriching capsule was chosen which can contain up
to 92 g of uranium. The manipulator for transporting the capsule within
the sampler and the valves used in isolating the areas performed adequately.