The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 29, 1997
Filed:
Aug. 29, 1995
Chien-Chang Lin, Fremont, CA (US);
General Electric Company, San Jose, CA (US);
Abstract
A pre-oxidation treatment for decreasing the amount of chromium deposited on out-of-core surfaces such as the internal surfaces of recirculation piping. Hydrogen peroxide is injected into the reactor coolant through the recirculation line during reactor shutdown after H.sub.2 addition has been terminated. A dilute acid solution (e.g., nitric acid) is also injected into the loop to serve as a catalyst to accelerate the oxidation reactions. An appropriate water pH (e.g., in the range of 5-6) is maintained by acid injection. The coolant temperature during shutdown is maintained at approximately 150.degree. C. or lower. The peroxide concentration in the recirculation piping is maintained at approximately 1 ppm or higher as needed. The oxidation process should be allowed to take effect in the proposed temperature range with the recirculation pump in operation for at least a few hours to 24 hours, depending on the temperature and the oxide film thickness. The Cr-enriched oxides can be readily oxidized by the hydrogen peroxide to a soluble chromate under proper conditions. Some of the radioactivities associated with the oxides will then be released into the coolant and consequently removed by the reactor water cleanup system.