Krypton cylinders

The preferred method of disposal of radioactive krypton isotopes, after being separated from other volatile fission products, is by dumping at sea as the compressed gas, confined in steel cylinders. According to a report by Bryant and Jones the cumulative quantities of Kr and in the environment by the year 2000 are such that these nuclides will pose no significant health problem. 

Of the noble gases, radioactive xenon has completely decayed after 1 y cooling, but krypton contains Kr with 10.7 y half-life. This isotope is produced in appreciable amounts, and though commonly it has been released to the atmosphere, this is no longer acceptable. Many processes have been devised for krypton removal. Krypton in dry, clean air is effectively trapped on a charcoal filter at cryogenic temperature however, because of explosion risk (due to reaction between radiolytically formed ozone and carbon), the favored process is condensation by liquid N2 (kiypton boils at -153 C) followed by fractional distillation. This removes >99% of %r. The krypton can be stored in pressurized cylinders until Kr has decayed (>100 years). 

Cylinders of compressed gases are often labeled to show how many SCF or standard cubic feet of gas they contain. 1 SCF of gas occupies a volume of 1 ft at a standard temperature and pressure of 0°C and 1 atm. A particular cylinder weighs 122 lbs when empty, and 155 lbs when filled with krypton gas at 26°C. How many SCF of Kr does this cylinder contain ... 

Krypton, neon, and xenon are rare atmospheric gases. Each is odorless, colorless, tasteless, nontoxic, monatomic, and chemically inert. All three together constitute less than 0.002 percent of the atmosphere with approximate concentrations in the atmosphere of 18 ppm for neon, 1.1 ppm for krypton, and 0.09 ppm for xenon. Few users of the three gases need them in bulk quantities, and the three are shipped most often in single cylinders and glass liter flasks. 

When disposal becomes necessary, vent neon, krypton, and xenon gas slowly to a well-ventilated outdoor location remote from personnel work areas and building air intakes. Do not dispose of any residual neon, krypton, and xenon in compressed gas cylinders. Return cylinders to the supplier with residual pressure, the cylinder valve tightly closed, and the valve caps in place. 

Under present regulations, cylinders of all types authorized for service with neon, krypton, and xenon must be requalified by hydrostatic test every 5 years with the following exceptions DOT-3A and 3AA used exclusively for krypton, neon, and xenon may be retested every 10 years under special requirements as given in 49 CFR 173.34(e)(15), or equivalent TC regulations [5, 6]. DOT-4 may be retested every 10 years and DOT-3C, 3E, and 4C require no periodic retest. 

Neon, krypton, and xenon are shipped most often in individual cylinders or in liter quantities in glass flasks since they are seldom used in bulk quantities. Neon is shipped as a liquefied, cryogenic gas in special insulated containers. 

The maximum authorized filling limit for neon, krypton, and xenon in approved types of cylinders is the marked service pressure of the cylinder at 70°F (21.1°C) (or, in the case of specification 3 A and 3AA cylinders meeting additional specified requirements, 10 percent in excess of the marked service pressure). Because commercial grades of xenon deviate markedly in physical properties from the ideal gas at elevated pressures, maximum filling limits for the specific commercial grade of xenon being used must be determined experimentally. 

By Air For gaseous neon, krypton, and xenon, aboard passenger aircraft in appropriate cylinders up to 150 lb (68 kg) maximum net weight per cylinder, and aboard... 

Neon and xenon are shipped in cylinders by rail, highway, water, or air as Nonflammable compressed gas. Krypton is shipped as Nonflammable compressed gas, n.o.s. ... 

Pressure relief devices authorized for use on containers of krypton and neon are the Type CG-1 rupture disk, the Type CG-4 and CG-5 combination rupture disk/fusible plugs, and the Type CG-7 pressure relief valve. [7] For xenon, the Type CG-1, CG-4, and CG-7 pressure relief devices are authorized. See CGA S-1.1, Pressure Relief Device Standards—Part 1—Cylinders for Compressed Gases, for further information and requirements. [7]... 

Standard valve outlet connections in the United States and Canada for cylinders of krypton, neon, or xenon are Connection CGA 580 for pressures up to 3000 psi (20 684 kPa) Connection CGA 680 for pressures between 3001 and 5500 psig (20 691 and 37 921 kPa) and Connection CGA 677 for pressure between 5501 and 7500 psig (37 928 and 51 711 kPa). Connection CGA 792 is the standard connection for cryogenic liquid withdrawal of neon. [8]... 

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