Low LET radiolysis escape yields for reducing radicals and H2 in pressurized high temperature water. (April 2016)

• Record Type: Journal Article
• Authors: Sterniczuk, Marcin; Yakabuskie, Pamela A.; Wren, J. Clara; Jacob, Jasmine A.; Bartels, David M.
• Is Part Of: Radiation physics and chemistry. Volume 121(2016:Apr.)
• Page Start: 35
• Page End: 42
• Publication Date: 2016-04
• Subjects: Radiolysis -- Hydrated electron -- Hydrogen atom -- G values -- High temperature -- Spur recombination; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2015.12.007
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: Low Linear Energy Transfer (LET) radiolysis escape yields ( G values) are reported for the sum ( G( H)+G(e-)aq ) and for G(H2 ) in subcritical water up to 350 °C. The scavenger system 1–10 mM acetate/0.001 M hydroxide/0.00048 M N2 O was used with simultaneous mass spectroscopic detection of H2 and N2 product. Temperature-dependent measurements were carried out with 2.5 MeV electrons from a van de Graaff accelerator, while room temperature calibration measurements were done with a 60 Co gamma source. The concentrations and dose range were carefully chosen so that initial spur chemistry is not perturbed and the N2 product yield corresponds to those reducing radicals that escape recombination in pure water. In comparison with a recent review recommendation of Elliot and Bartels (AECL report 153-127160-450-001, 2009), the measured reducing radical yield is seven percent smaller at room temperature but in fairly good agreement above 150 °C. The H2 escape yield is in good agreement throughout the temperature range with several previous studies that used much larger radical scavenging rates. Previous analysis of earlier high temperature measurements of Gesc ( OH) is shown to be flawed, although the actual G values may be nearly correct. The methodology used in the present report greatly reduces the range of possible error and puts the high temperature escape yields for low-LET radiation on a much firmer quantitative foundation than was previously available. Graphical abstract: Highlights: Water radiolysis escape yields for (G(e-aq )+G(H) ), and G(H2 ) are measured to 350 °C. Resulting high temperature escape yields are on a much better quantitative foundation. Reconsideration of available high-temperature G(OH) shows that analysis is flawed. New interpolation formulas are recommended for all of the radiolytic escape yields.