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Sub- and Supercritical Water Radiolysis


Experimental Determination of the Yields of Molecular Products in Water Irradiated by Accelerated Protons in the Test Bench "PROTOKA" at Supercritical Pressure and Temperatures 280-500 °C

Tech Area / Field

  • FIR-EXP/Experiments/Fission Reactors

3 Approved without Funding

Registration date

Leading Institute
Kurchatov Research Center, Russia, Moscow


  • SRI International / Materials Research Laboratory, USA, CA, Menlo Park

Project summary

The purpose of work is experimental receiving of values of observed yields of stable water products and aqueous solutions radiolysis for conditions of the primary circuit of Generation IV Light Water Reactors designed in the USA. These data are supposed to be received on the test bench “ PROTOKA ” (FSI RRC “Kurchatov Institute”) with the help of accelerated protons as a radiation equivalent of the nuclear reactor active zone. Irradiation of the primary circuit coolant imitator is supposed to conduct at:
  • pressures more than 25 MPa,
  • temperatures 280-500 0C,
  • absorbed dose rates 0,5 –1 Mrad/s.

The planned researches will allow to receive the quantitative data on kinetics of the water coolant radiolysis in supercritical areas, for which now no reliable experimental data practically exist. Irradiation of the coolant imitator by a beam of cyclotron accelerated protons, firstly, reproduces influence of one of the main reactor radiation components (fast neutrons as ionization of water due to their influence on water proceeds at the expense of recoil protons) and, secondly, allows to achieve the absorbed doze rate characteristic to nuclear power reactors on the test bench. Thus, the experimental data obtained in modelling conditions will allow to understand the laws of radiolytic processes in the coolant of the primary circuit of designed in the USA Generation IV Light Water Reactors. The set of experimental results and theoretical investigations is supposed to be used for substantiation of the constructional materials choice in the equipment of the primary circuit of Generation IV Light Water Reactors.

Scientists from FSI RRC “Kurchatov Institute”, specializing on experimental and theoretical investigations of water and aqueous solutions radyolysis will participate in the project from the Russian side. Scientists included in the creative groups, have practical work experience on acting reactors as well as on test benches and also in developing of mathematical models and computer codes for descriptions of radiation-chemical processes in water coolant and constructional materials of nuclear power reactors.

For study of water radiolysis in conditions typical for primary circuit of nuclear reactors Russian scientists developed, made and verified the test bench PROTOKA with an open loop. PROTOKA construction gives us a possibility to vary (imitating an active zone of the nuclear power reactor) temperatures, pressures and absorbed dose rates in the coolant on a target. The analytical part of the test bench supplied with appropriate tools and computer facilities allows to determine chemical composition of water coolant at the entrance and exit of the target. Target irradiation is made by a beam of protons accelerated in a cyclotron. Use of the cyclotron as a source of irradiation gives a possibility to fix accurately radiation and thermal factors of influence and also produces convenient regulation of experimental parameters, high maneuverability of the test bench and nuclear safety of experiments. It is important to mark a much lower cost of experiments in the laboratory with the use of a cyclotron in comparison with reactor experiments. Russian scientists have experience of operating the PROTOKA and also of quantitative chemical analysis of stable radiolytic products of water and aqueous solutions – imitators of the primary circuit for different types of power reactors.

From the American side an expert of SRI International, engaged on problems of constructional materials choice for the designed now in the USA of a light water reactor participates in the work. The American side has experience of creation and operating of stands for research of constructional materials properties for nuclear power reactors in supercritical water without irradiation.

Joint efforts of both sides will allow us to conduct experiments on investigations of water and aqueous solutions radiolysis in supercritical conditions and to receive data necessary for a substantiation choice by the American side of constructional materials for the designed in the USA Generation IV Light Water Reactors.

The realization of the project answers the purposes of ISTC because in the project directed to develop a new generation of civil reactors in the USA, participation of Russian scientists in the classified research projects is supposed.

At the first stage it is planned to develop a program, in which requests to radiolysis researches of the water coolant at supercritical conditions for the substantiation of test specifications of structural components for the designed in the USA Generation IV Light Water Reactors will be formulated. At this very stage requests to the experimental stand should be also adjusted.

At the second stage performed in parallel with the first there will be made modernizing of the test bench “PROTOKA” in correspondence with the Technical Task and developed on its basis Technical Project with due regard for research program requests and experimental safety.

The third stage of the project will consist of the experimental measuring of observed yields of stable products of supercritical water and aquoues solutions of a given quality radiolysis in compliance with the program of experiments agreed with the American side.

At the last fourth stage analysis of the obtained data will be conducted and conclusions about the mechanism of radiolysis process in supercritical water and coolant imitators for the primary circuit of Generation IV Light Water Reactors will be made, recommendations for irradiation influence account during corrosion tests of structural components intended for these reactors will be prepared.


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