AN EVALUATION OF THE SULFURIC ACID-SODIUM NITRITE ETCH FOR ZIRCALOY-2

Preliminary experiments indicate that there are no significant differences in the corrosion rates of zirconium or Zircaloy-2 after etching with the nitric--hydrofluoric solution or the sulfuric--nitrite solution, provided proper etching and washing techniques are followed. Incomplete removal of the residual etchant is deleterious to the corrosion resistance; however, this effect in the case of the sulfuric--nitrite solution is not as pronounced as in the case of the nitric--hydrofluoric acid solution. The anticipated advantages in the new etch were not completely realized. Additional development aimed at modifying the sulfuric--nitrite etch would have to be performed in order to overcome the disadvantages before recommendation for the adoption of the etch could be made. (auth