Development of protective coatings to reduce hydrogen and tritium permeation

Journal Article · Sat Sep 01 00:00:00 EDT 1984 · Nucl. Technol.; (United States)

OSTI ID:6029752

Muhlratzer, A; Esser, H G; Zelinger, H

An important demand with respect to the operability of a nuclear process heat system, such as the prototype plant for nuclear process heat, is the complete retention of tritium. A significant contribution to the solution of this problem is expected by a drastic reduction of the permeation of hydrogen and tritium through the heat exchanger walls. The most promising way to prevent this permeation appears to be to coat the parts concerned, which are made of high-temperature alloys, with oxide layers. Through preoxidation under well-defined conditions, it should be possible to obtain oxide layers that promise a lasting inhibition of the hydrogen and tritium permeation under process conditions. The process used to obtain permeation-resistant oxide layers on the high-temperature alloys in question--in particular on Hastelloy-X--is characterized by the application of a low oxidation potential, so that Cr/sub 2/O/sub 3/ layers will form. Steam at low pressure in argon with and without the addition of hydrogen is used as the oxidizing agent. Furthermore, the formation of dense Cr/sub 2/O/sub 3/ layers is conditional on a suitable pretreatment. The best layers, with respect to the inhibition of permeation and to stability in the steam reforming process gas, were obtained by preoxidizing at 1273 K under special thermocycling conditions. They reduced the permeation by a factor of over 2000, which increased to over 3000 under the effects of a process gas exposure. Chemical vapor deposition Al/sub 2/O/sub 3/ coatings were tested to see if they would be suitable as alternatives. High inhibiting factors (over 1000) were obtained with Al/sub 2/O/sub 3/ coatings deposited on preoxidized substrates.

• Research Organization: M.A.N.-Maschinenfabrik Augsburg-Nurnberg, Neue Technologie, Munich
• OSTI ID: 6029752
• Journal Information: Nucl. Technol.; (United States), Vol. 66:2
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
36 MATERIALS SCIENCE
HEAT RESISTING ALLOYS
PERMEABILITY
PROTECTIVE COATINGS
HTGR TYPE REACTORS
REACTOR MATERIALS
HYDROGEN
DIFFUSION
PROCESS HEAT REACTORS
TRITIUM
ALUMINIUM OXIDES
CHROMIUM OXIDES
CORROSIVE EFFECTS
INHIBITION
MATERIALS TESTING
OXIDATION
OXIDES
STEAM
SURFACE COATING
THERMAL CYCLING
VERY HIGH TEMPERATURE
ALLOYS
ALUMINIUM COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM COMPOUNDS
COATINGS
DEPOSITION
ELEMENTS
GAS COOLED REACTORS
GRAPHITE MODERATED REACTORS
HEAT RESISTANT MATERIALS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
MATERIALS
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
RADIOISOTOPES
REACTORS
TESTING
TRANSITION ELEMENT COMPOUNDS
YEARS LIVING RADIOISOTOPES
210900* - Nuclear Power Plants- Process Heat Reactors- (-1987)
210300 - Power Reactors
Nonbreeding
Graphite Moderated
360101 - Metals & Alloys- Preparation & Fabrication
360105 - Metals & Alloys- Corrosion & Erosion