Cryosorption pumping of 95% deuterium--5% helium on molecular sieve 5A at 4. 2 K

Conference · Sat Jan 01 04:00:00 EST 1977

OSTI ID:5331245

Fisher, P W; Watson, J S

Plasma recovery systems in fusion reactors must be capable of exhausting a mixture of deuterium, tritium, and helium from the reactor between burns (and possibly during burns) to remove leaking or diverted plasma. Concentrations of helium in these mixtures may range from 1 to 15 percent. An Excalibur CVR 1106 cryosorption pump was tested to determine pumping speeds of 95 percent deuterium--5 percent helium. Tests were run with two different cooling configurations for the inner chevron (the chevron next to the cryosorption panel): (1) liquid helium boil-off vapor was routed through the chevron prior to venting (the normal mode) and (2) 77/sup 0/K helium was backflushed through the chevron. Three distinct types of behavior were observed. At feed rates of <1.2 x 10/sup -4/ torr-liter sec/sup -1/ cm/sup -2/, speeds decreased slightly with loading, regardless of the temperature of the inner chevron. Speeds as high as 3.7 liters sec/sup -1/ cm/sup -2/ were observed when the inner chevron was cooled by boil-off vapor; however, speeds were lower with the 77 K chevron (approximately 2.2 liters sec/sup -1/ cm/sup -2/). At high feed rates (>1.2 x 10/sup -4/ torr-liter sec/sup -1/ cm/sup -2/), behavior was dependent on the temperature of the inner chevron. All runs began with a rapid decrease in pumping speed that resulted from the accumulation of helium in the test chamber after the frozen deuterium blocked the cryosorption surface. When the inner chevron was cooled by boil-off vapor, the pump recovered and the speed increased and remained steady near 1.9 liters sec/sup -1/ cm/sup -2/. If the inner chevron was held at 77/sup 0/K, operation had to be terminated because system pressurization resulted in rapid cryogenic runaway. When the pump was cooled by liquid helium boil-off vapor, increased pressure affected the helium boil-off rate sufficiently to keep the inner chevron just cold enough to collect all (or a large fraction) of the deuterium, thus leaving the cryosoprtion panel clear to pump helium.

• Research Organization: Oak Ridge National Lab., Tenn. (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5331245
• Report Number(s): CONF-771029-84
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700209* -- Fusion Power Plant Technology-- Component Development &amp; Materials Testing
ADSORBENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CRYOGENIC FLUIDS
CRYOPUMPS
DEUTERIUM
ELEMENTS
FLUIDS
HELIUM
HYDROGEN ISOTOPES
ISOTOPES
LABORATORY EQUIPMENT
LIGHT NUCLEI
MOLECULAR SIEVES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
PERFORMANCE TESTING
PUMPS
RADIOISOTOPES
RARE GASES
RECOVERY
STABLE ISOTOPES
TESTING
THERMONUCLEAR REACTORS
TRITIUM
TRITIUM RECOVERY
VACUUM PUMPS
VACUUM SYSTEMS
YEARS LIVING RADIOISOTOPES