Radiolytic gas generation in plutonium contaminated waste materials

Abstract

Many plutonium contaminated waste materials decompose into gaseous products because of exposure to alpha radiation. The gases generated (usually hydrogen) over long-storage periods may create hazardous conditions. To determine the extent of such hazards, knowing the gas generation yields is necessary. These yields were measured by contacting some common Rocky Flats Plant waste materials with plutonium and monitoring the enclosed atmospheres for extensive periods of time. The materials were Plexiglas, polyvinyl chloride, glove-box gloves, machining oil, carbon tetrachloride, chlorothene VG@ solvent, Kimwipes@ (dry and wet), polyethylene, Dowex-1 resin, and surgeon's gloves. Both plutonium-239 oxide and plutonium-238 oxide were used as radiation sources. The gas analyses were made by mass spectrometry and the results obtained were the total gas generation, the hydrogen generation, the oxygen consumption rate, and the gas composition over the entire storage period. Hydrogen was the major gas produced in most of the materials. The total gas yields varied from 0.7 1 to 16 cubic centimetres (standard temperature pressure) per day per curie of plutonium. The oxygen consumption rates varied from 0.0088 to 0.070 millimoles per day per gram of plutonium oxide-239 and from 0.0014 to 0.005 I millimoles per day per milligram plutonium 238. ' A. A. Miller. "Radiation Chemistry of Polyvinyl Chloride."

A computer model of gas generation and transport within TRU waste drums

“…To conduct an independent evaluation, the SRL model was used to determine pressure increases and gas concentrations within the TRUPACT container. While the gas generation rates used in the model are well supported by laboratory data (1), higher values have appeared in the literature (3). It has also been suggested that gas generation from thermal degradation and bacterial decomposition of organic material in the waste may contribute to hydrogen gas formation.…”

Evaluation of residue drum storage safety risks

“…These mechanisms include (1) radiolysis of water, (2) radiolytic degradation of organic material, (3) acidmetal reactions between mild steel drums and acid vapors, and (4) reaction of water with reactive metals. These gas generation mechanisms result in the generation of hydrogen, carbon dioxide, carbon monoxide, and other gases.…”

“…However, the potential safety risks appear to be sufficiently real to warrant further investigation. The potential safety risks identified during the study described in this report include (1) residue drums pressurization, (2) hydrogen accumulation in residue drums, (3) contamination containment loss, (4) drum and drum-vent filter assembly corrosion, (5) metal residue container corrosion, and (6) pyrophoric or unstable compound formation in drums containing plutonium or reactive metals. All the information required to determine the extent of the hazard posed by these safety risks is not currently available.…”

“…These steps include (1) drum head space gas sampling studies, (2) drum and residue inspection programs, and (3) residue sampling studies. These recommended studies will be costly, but a better definition of the safety problems actually existing in the residue drum backlog would allow steps to be taken to address the safety risks before a real problem occurs.…”

Hydrogen generation in tru waste transportation packages

“…Latex is the commercial name for polybutadiene and polyisoprene. The bounding G vales for Latex are estimated as G(H2)=0.7, G(1lam gas)=0.9 and G(net gas)=O.9 (Kazanjian 1976;Zerwekh 1979;Bohm 1973).…”