Supercritical Water Radiolysis Chemistry Supercritical Water Corrosion

The direct measurement of the chemistry in reactor cores is extremely difficult. The extreme conditions of high temperature, pressure, and radiation fields, are not compatible with normal chemical instrumentation. There are also problems of access to fuel channels in the reactor core. For these reasons, all reaction vendors and many operators have extensively used theoretical calculations and chemical models to model the detailed radiation chemistry of the water in the core and the consequences for materials. The results of these model calculations can be no more accurate than the fundamental information fed into them, and serious discrepancies remain between model calculations and reactor experiments [1,2,3]. For proposed supercritical water cooled reactors, there is barely any information available to begin construction of a radiolysis model for the anticipated pressure (250bar) and temperatures (up to 500C). The objective of this work is to generate the necessary radiation chemistry data (yields and reaction rates) needed to model chemistry in a supercritical water cooled reactor. Beta/gamma yields and reaction rates are measured using electron accelerators at Notre Dame University. Yields from neutron radiolysis are being measured at the University of Wisconsin Reactor Facility. The initial goal is to at least estimate corrosion potentials likely to prevail in the core of such a reactor. This will guide design and feasibility studies for the primary heat transport system. At both facilities, an evaluation is being made of the use of added hydrogen to suppress supercritical water.