Helium grades

The ammonia (Matheson anhydrous) was purified by fractional condensation and distillation in vacuum. Research grade helium (Matheson) was dried over 5A molecular sieve prior to use. 

INERT ATMOSPHERE. Because the alkali metals react voraciously with air and moisture, extreme care must be employed in handling them after they have been purified. The use of a purified helium-atmosphere dry box facilitated the preparation of the solutions for thermal analysis. Welding grade helium was purified... 

The main components of the HTR-10 such as the reactor pressure vessel, the steam generator vessel and its internal parts, the helium circulator and the core matallic internal are fabricated by the domestic factories which have the ability and experience of manufactring PWR s components. The graphite of the core internal and part of the safety grade helium valves will be imported from the foreign suppliers. 

The maximum requirement of 4 x 10 ft of helium until the year 2000, assuming that all nuclear power in the United States were generated in HTGR plants, would only commit about 2% of the high-grade helium resources and a completely insignificant quantity of all helium resources. 

G.E.C. Bell, P.S. Bishop, Compatibility of Vanadium AUoys with Reactor-grade Helium for Fusion Reactor Applications, CONF-930318—3, US-DOE, 1993. 

Carrier Gas—Chromatographic grade helium or hydrogen is recommended. 

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