CORROSION STUDIES FOR THE HRT CHEMICAL PROCESSING PLANT

Abstract

The corrosion resistance of a number of materials considered for use in the HRT Chemical Processing Plant was determined in H/sub 2/SO/sub 4/ solutions. Ta was found to be fully resistant to boiling 4 M and l0.8 M H/sub 2/SO/sub 4/ solutions used for the dissolution of corrosion and fission products removed from the homogeneous-reactor fuel solution. Ta was immune to H/sub 2/ embrittlement in these solutions. Crystal-bar Zr and Zircaloy-2 were fully resistant to attuck by boiling 4 M H/sub 2/SO/sub 4/ solution but were attacked at rates of 5 to l0 mpy in boiling l0.8 M H/sub 2/SO/sub 4/ solution. Carpenter 20-Cb stainless steel was completely resistant to 4 M H/sub 2/SO/sub 4/ solutions at 38 deg C, the temperature in the decay storage vessels of the chemical proces sing plant, and generally was resistant to similar H/sub 2/SO/sub 4/ solutions at atmospheric boiling temperatures ~ ll0 deg C. In a few isolated cases, however, the alloy was prone to stress-corrosion cracking and to knife-line attack in several of the boiling 4 M H/sub 2/SO/sub 4/ environments. Corrosion rates of types 347 and 3l6 stainless steel in boiling 4 M H/sub 2/SO/sub 4/ solution were in excess ofmore » 75,000 mpy; however, in the presence of synthetic corrosion and fission products, corrosion attack was reduced to l0 mpy or less. A similar, but less drastic, reduction in the rate of attack on Carpenter 20-Cb stainless steel was experienced with additives present in the boiling 4 M H/sub 2/SOs/bu 4/ solution. The corrosion rate of the latter alloy in boiling and helium-aerated 4 M H/sub 2/ SO/sub 4/ solution was accelerated by Rus a fission-product element. (auth)« less