The Idaho Chemical Processing Plant currently stores irradiated nuclear fuel in fuel storage basins. Historically, fuel has been stored for over 30 years. During the 1970's, an algae problem occurred which required higher levels of chemical treatment of the basin water to maintain visibility for fuel storage operations. This treatment led to higher levels of chlorides than seen previously which caused increased corrosion of aluminum and carbon steel, but has had little effect on the stainless steel in the basin.Corrosion measurements of select aluminum fuel storage cans, aluminum fuel storage buckets, and operational support equipment have been completed. Aluminum has exhibited good general corrosion rates, but has shown accelerated preferential attack in the form of pitting. Hot dipped zinc coated carbon steel, which has been in the basin for approximately 40 years, has shown a general corrosion rate of 4 mpy, and there is evidence of large shallow pits on the surface. A welded type 304 stainless steel corrosion coupon has shown no attack after 13 years exposure.Galvanic couples between carbon steel welded to Type 304 stainless steel occur in fuel storage yokes exposed to the basin water. These welded couples have shown galvanic attack as well as hot weld cracking and intergranular cracking. The intergranular stress corrosion craclcing is attributed to crevices formed during fabrication which allowed chlorides to concentrate.Key Words: Nuclear, Fuel, Storage, Basins, Aluminum, Carbon Steel, Stainless Steel, Welds, ' Galvanic, Stress Corrosion, Cracking, Chlorides, Nitrates, Water ' I. BackgroundThe Idah_ Chemical Processing Plant (ICPP), located at the Idaho National Engineering Laboratory near idaho Falls, Idaho, is currently operated by Westinghouse Idaho Nuclear Company, Inc., under contract from the Department of Energy. The past mission of the ICPP was as a nuclear fuel reprocessing plant with multiple headend facilities to process aluminum, stainless steel and zirconium clad fuels by acid dissolution. In 1992 the mission was changed from processing nuclear fuel to receiving, storing, and preparing spent nuclear fuels and radioactive wastes for disposition for the Department of Energy. This change in mission required a thorough review of equipment and inspection procedures for long term under-water storage of nuclear fuel.
II. IntroductionThe aqueous nuclear fuel receiving and storage basin at the ICPP handles a diverse mixture of nuclear fuel materials. The principal fuel materials in the ICPP-603 basin include: aluminum clad fuel -usually from test and research reactors, stainless steel clad fuels from liquid metal cooled experimental reactors, and zirconium clad fuel from Naval reactors. In addition, there have also been occasional experimental nuclear fuel elements that have been designed to test variations in reactor design, fuel composition, or cladding materials.In the past, fuel materials have been received from goverment reactors for processing at ICPP. Some of the fuel materials were scra...
