As the West Valley Demonstration Project (WVDP) continues vitrification operation and begins decontamination activities, it is vital to continue to maintain the integrity of the high-level waste tanks and prevent further corrosion that may disrupt the operation. This paper describes the current operational status and some corrosion concerns with corresponding control measure recommendations.
The only commercial nuclear fuel reprocessing facility ever to operate in the United States is located on approximately 200 acres of the 3,345-acre Western New York Nuclear Service Center (WNYNSC) near West Valley, New York, The WNYNSC is owned by New York State through the New York State Energy Research and Development Authority (NYSERDA).
The commercial nuclear fuel reprocessing facility was leased to a private company sad operated from 1966 to 1972 to recover useable uranium and plutonium. Approximately 640 tons of spent nuclear fuel were reprocessed generating about 600,000 gallons of liquid high-level radioactive waste (HLW), The HLW was placed in storage in an underground tank (8D-2) contained within a concrete vault. Tank 8D-1, an identical tank, was used as the spare backup tank.
In 1980, the West Valley Demonstration Project (WVDP) Act was signed by the President of the United States to become Public Law 96-368. The Act directs the Department of Energy (DOE) to solidify the HLW stored at the site into a durable, solid form suitable for shipment to a federal repository, clean and close the facilities used; and dispose of the low-level and transuranic wastes collected during Project operations.
In 1981 DOE selected West Valley Nuclear Services Company, Inc. (WVNS), a wholly owned subsidiary of Westinghouse Electric Corporation as prime Project contractor. DOE and WVNS assumed operational control of the site in 1982.
Within Tank 8D-2, the HLW had separated into two phase a relatively clear liquid and a thick layer of solid sludge. The stabilization of this waste was planned to be conducted in two stages: 1) pretreatment to separate the salts from the radioactive components, and 2) removal of the HLW from 8D-2 and vitrification into a borosilicate glass waste form using a slurry-fed ceramic melter (SFCM).
The pretreatment consisted of processing the liquid phase of the waste through an ion-exchange process using zeolite (a synthetic, sodium aluminosilicate mineral) ion-exchange media. The sludge in the bottom of 8D-2 was then mobilized and mixed with water (washed) to dissolve sulfates and other salts. The wash water was then processed through the zeolite ion-exchange system, Pretreatment operations were started in 1988 and completed in 1995 resulting in approximately 20,000 drums of cemented low-level waste (LLW).
During the second stage of stabilization the HLW mixture (consisting of the sludge and the zeolite) is removed from Tank 8D-2 and transferred to the Vitrification Facility where glass-forming chemicals are added and the mixture is fed to a 52-to L joule-heated ceramic melter. The melter is then heated to approximately2,0000F (1,093ºC ) to produce a homogeneous molten waste/glass blend that is cast into 2-foot (0.6 m) diameter by 10-foot (3.0 m) long stainless steel canisters.