Method for protecting components of a primary system of a boiling water reactor in particular from stress corrosion cracking

Abstract

A method for protecting the components of the primary system of a boiling water reactor, especially against stress cracking corrosion, includes feeding a reducing agent into the primary coolant in order to reduce the number of substances having a oxidizing effect or in order to modify the electrochemical potential of the component surfaces covered with an oxide layer to negative values. An alcohol that can be oxidized in the conditions of a reactor is fed in as a reducing agent, preferably in a liquid form, into the primary coolant. The component surfaces are provided with a blank coating or a single intrinsic oxide coating.

Description

[0001] This is a continuation of U.S. patent Ser. No. 10 / 715,069, filed Nov. 17, 2003, which is a continuation of International Application No. PCT / EP02 / 05274, filed May 14, 2002.BACKGOUND [0002] The invention lies in the boiling water reactor technology field. More specifically, the invention relates to a method for protecting the components of the primary system of a boiling water reactor in particular from stress corrosion. In a boiling water reactor, the coolant which comes into contact with the reactor core is known as primary coolant, and the lines and components which are exposed to the primary coolant are known as the primary system. In addition to the reactor pressure vessel, the primary system of a boiling water reactor includes systems of lines as well as various internal fittings and pumps. The components generally consist of stainless steel, for example of a CrNi steel, or an Ni-base alloy, such as Inconel® 600 (Inco Alloys International, Inc.). Radiolysis of the primar...

AI Technical Summary

Benefits of technology

[0008] An object of the present invention is to provide a method for protecting the components of the primary system of a boiling water reactor which overcomes the above-mentione

Problems solved by technology

The oxidizing conditions which result from the excess of oxidizing agents promote corrosion, in particular stress corrosion cracking, of the components.

A drawback of the conventional method is that relatively large quantities of hydrogen are required to ensure sufficient protection against corrosion.

The high demand for hydrogen, which entails corresponding costs, is attributable not least to the fact that the electrochemical oxidation of the hydrogen on the component surfaces which are covered with an oxide layer is subject to considerable reaction inhibition, and this has to be compensated for by increased hydrogen concentrations.

A further drawback is the outlay on apparatus for metering the gaseous hydrogen.

A problem associated with very high alcohol concentration is that a relatively large portion of the al

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