Baidak, A.

Duff, J.

Parker-Quaife, E.

Pimblott, S. M.

Sims, H.

BSU Digital Library

Тезисы докладов Пленарного заседания / Plenary Session Abstracts                                   June 25-26,2015                                    
3 
DEVELOPING EXPERIMENTAL CAPABILITY FOR 
INVESTIGATION OF FREE RADICAL PROCESSES UNDER LIGHT
WATER REACTOR OPERATING CONDITIONS 
Baidak A.1,2, Duff J.3, Sims H.4, Parker-Quaife E.1,2, Pimblott S.M.1,2
1 University of Manchester, Dalton Cumbrian Facility,  
Westlakes Science & Technology Park, Moor Row, Cumbria, CA28 3HA 
2 University of Manchester, School of Chemistry, Oxford Road, Manchester, M13 9PL 
3 University of Manchester, School of Materials, Oxford Road, Manchester, M13 9PL 
4 National Nuclear Laboratory, Harwell Science Park, Didcot, Oxon OX11 0QT, UK 
Water radiolysis at extreme conditions of high temperature and high
pressure (HTHP) is an important issue in a number of areas in nuclear reactor
technology, especially in the high temperature corrosion of structural materials
in the primary circuit of Light Water Reactors (LWRs), which is noticeably
enhanced by the oxidizing radical products of water radiolysis. Mitigation of
the detrimental effects of water radiolysis on reactor’s structural components 
promotes the long-term viability of water-cooled nuclear systems. In addition,
the choice of promising materials for the next generation of nuclear reactors
will rely on the fundamental understanding of the radiation chemical processes
in water under extreme conditions of high heat, pressure and mixed radiation
fields. 
Direct examination of the free radical processes in nuclear reactor cores
is extremely difficult due to the intense mixed radiation fields and HTHP [1].
One way to circumvent these limitations is to design an experiment in which
water (or aqueous solution)  under study is irradiated in the high tempera-
ture/high pressure conditions using conventional radiation sources. In my talk
I will describe the design of experimental capability dedicated to the study of
radical processes arising from the radiolysis in HTHP flowing water using ei-
ther gamma (Co-60) or proton beam irradiation. 
In the heart of our experimental setup is a recirculation loop that is capa-
ble of maintaining water inside the irradiation cell (autoclave) at temperatures
up to 350°C and pressures up to 200 atm. Essentially, the flow system consists
of a feed tank with aqueous solution under study, low and high pressure loops
with associated pumps, a preheater, an autoclave and a cooler. Water chemis-
try control is of a great importance, hence, the automated data acquisition sys-
tem continuously monitors pressure, temperature, dissolved hydrogen and dis-
solved oxygen content and water conductivity before and after irradiation. The
water chemistry can be easily modified by saturation/doping with the additives
of interest, such as hydrogen, oxygen or ionic species. 
Тезисы докладов Пленарного заседания / Plenary Session Abstracts                                   June 25-26,2015                                    
 
4 
 
During water radiolysis a number of radical transients and molecular 
products are formed, as shown by simplified Equation 1: 
 
H2O → e-aq,·OH, ·H, H+,·HO2, H2O2, H2                   (1) 
                                                                                     
The “yields” of radical species (e-aq,·OH, ·H) are functions of time be-
cause their diffusive escape is in competition with recombination processes. 
At room temperature within about a microsecond the recombination reactions 
are completed, while the surviving radicals can be measured with appropriate 
scavengers as an “escape yield”. Scavenged yields of major radical products 
formed during water radiolysis at room temperature are well established. 
However, radiation chemical yields and reaction rates of primary radicals in 
the radiolysis of water above 300°C are either not measured at all or incon-
sistent; current reactor models include calculations based on extrapolated  
data [2].  
Our first experiments will target radiation chemical yields for the free 
radicals ·H and e-aq [3]. Corresponding G values will be determined for low 
and high linear energy transfer (LET) types of radiation using, respectively, 
gamma and ion beam radiolysis. Water radiolysis in a wide range of high tem-
perature and pressure conditions (up to 350°C and 200 atm) will be performed. 
N2O and ethanol-d5 will be used to scavenge e-aq and ·H, respectively. Very 
sensitive mass spectroscopy technique (or its combination with gas chroma-
tography) will be employed to measure N2, HD, H2 or O2 formed either as sta-
ble products of water radiolysis (H2, H2O2→O2) or as the products of scaveng-
ing reactions (N2O→N2, C2D5OH→HD). 
Preliminary data will be used to demonstrate that the described rig can be 
successfully employed to study free radical processes in aqueous systems at 
HTHP conditions. The importance of the radiolysis experiments in water at 
HTHP is hard to underestimate: described studies will produce essential ther-
modynamic and kinetic data that will aid in development of models relevant to 
nuclear reactor water chemistry behavior.  
References: 
1. Edwards, E. J. et al. Review of Scientific Instruments, 78, 2007, 124101-1–124101-11. 
2. Guzonas, D. et al. Nuclear Technology, 179, 2012, 205-218. 
3. Janik, D et al. J. Phys. Chem. A, 111, 2007, 7777-7786. 
 


Developing experimental capability for investigation of free radical processes under light water reactor operating conditions

http://elib.bsu.by/bitstream/123456789/119603/1/3-4.pdf

Developing experimental capability for investigation of free radical processes under light water reactor operating conditions

Abstract

Similar works

Full text

Available Versions

BSU Digital Library