Radiolytic gases, generation

L.R. Dole and H.A. Friedman, Radiolytic gas generation from cement-based waste hosts for DOE low-level radioactive wastes, Report No. CONF-860605-14 (Oak Ridge National Laboratory, 1986). 

Two additional applications of Sheba are being pursued. We hope to continue to provide the facility for extensions of the measurements described above. In addition, we would like to pursue the development of a true solution burst capability vrith information generated from experiments with the present assembly. We propose to separately evaluate radiolytic gas formation and thermal expansion as quench mechanisms in solution burst machines. A high pressure (6 atm) head has been fabricated for Sheba which will allow the demonstration of depressurization of an operating solution assembly as a scram mechanism. ... 

Fundamental research seems to be necessary in all cases where components normally are tested with pure steam instead with nuclear steam, which always has a small content of radiolytic gas. To avoid handling pure hydrogen and pure oxygen in a laboratory it could be possible to generate radiolytic gas by an electorolytical apparatus continuously and in small quantities. Such experiments can be very instructive about the accumulation of the radiolytic gas, about the natural circulation effects in components with stagnating steam atmosphere and about the possibilities to get a passive transport of the enriched steam back to the RPV or to another line with intensive steam flow. 

Since its first modem application in the late fifties, radiolysis has been extensively employed for generating transient ion-dipole complexes in the gas phase and to investigate their reactivity in the absence of the perturbing effects of solvation and ion pairing. The growing impact of the radiolytic technique in the gas-phase... 

The gas-phase base-induced elimination reaction of halonium ions was thoroughly investigated in radiolytic experiments22. Radiolytically generated acids C/JH5+ (n = 1,2) were allowed to react at 760 Torr with selected 2,3-dihalobutanes to form the halonium intermediates which, in the presence of trimethylamine, undergo base-induced bimolecu-lar elimination as shown in Scheme 6. This elimination reaction occurs in competition with unimolecular nucleophilic displacement to the cyclic halonium ion and subsequent rearrangement. Isolation and identification of the neutral haloalkenes formed and kinetic treatment of the experimental results indicated that 3-halo-1 -butene is formed preferentially with respect to the isomeric 2-halo-2-butenes and that the bimolecular elimination process occurs predominantly via a transition state with an anti configuration22. 

Fig. 8.3. An example of a gas chromatogram of the base-damage to DNA after exposure to hydroxyl radicals (generated radiolytically) - study of the trimethyl-silylated acidic hydrolysate of the modified DNA (modified from Dizdaroglu, 1988 with permission). Peaks I, phosphoric acid II, thymine III and Ilia, cytosine IV and IVa adenine V and Va guanine I uracil 2 5,6-dihydrothymine 3 5-hydroxy-5,6-dihydrothymine 4 5-hydroxyuracil 5 5-hydroxy-5,6-dihydrouracil 6 5-hydroxycytosine 7 cis-thymine glycol 8 /ra .s-thymine glycol 9 5,6-dihydroxyuracil 10 4,6-diamino-5-formamidopyr-imidine 11 8-hydroxyadenine 12 2,6-diamino-4-hydroxy-5-formamidopyrimidine 13...

Recent research into the Ritter reaction has concentrated on alternative means of generating the carbocation. Radiolytically formed carbocations have been reacted in the gas phase with aromatic and aliphatic cyanides yielding the corresponding nitrilium ions, which undergo condensation with water to yield A -alkylamides. 

Radiochemical sterilization (RCS) is an emerging technology. It is based on low-dose radiation sterilization in a dry environment at low temperatures in conjunction with the use of radiolytically and controllably generated formaldehyde gas at low levels. Details of the RCS process are described in the following excerpt from Shalaby, S.W., Doyle, Y., Anneaux, B.L., Carpenter, K.A., Schiretz, F.R. Radiochemical Sterilization and its use for Sutures (Nuclear Instruments and Methods in Physics Research B (2003) 110-114) ... 

The design of any component of the containment system shall take into account, where applicable, the radiolytic decomposition of liquids and other vulnerable materials and the generation of gas by chemical reaction and radiolysis. 

Generation of hazardous gases caused by chemical and radiolytic effects (for example, the generation of hydrogen gas caused by radiolysis) and the buildup of overpressure ... 

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