Electrochemical probing of high-level radioactive waste tanks containing washed sludge and precipitates

Conference · Mon Dec 01 04:00:00 EST 1986

OSTI ID:6928639

Bickford, D F; Congdon, J W; Oblath, S B

At the US Department of Energy's Savannah River Plant, corrosion of carbon steel storage tanks containing alkaline, high-level radioactive waste is controlled by specification of limits on waste composition and temperature. Processes for the preparation of waste for final disposal will result in waste with low corrosion inhibitor concentrations and, in some cases, high aromatic organic concentrations, neither of which are characteristic of previous operations. Laboratory tests, conducted to determine minimum corrosion inhibitor levels indicated pitting of carbon steel near the waterline for proposed storage conditions. In situ electrochemical measurements of full-scale radioactive process demonstrations have been conducted to assess the validity of laboratory tests. Probes included pH, Eh (potential relative to a standard hydrogen electrode), tank potential, and alloy coupons. In situ results are compared to those of the laboratory tests, with particular regard given to simulated solution composition. Transition metal hydroxide sludge contains strong passivating species for carbon steel. Washed precipitate contains organic species that lower solution pH and tend to reduce passivating films, requiring higher inhibitor concentrations than the 0.01 molar nitrite required for reactor fuel reprocessing wastes. Periodic agitation, to keep the organic phase suspended, or cathodic protection are possible alternatives to higher nitrite inhibitor concentrations.

• Research Organization: Du Pont de Nemours (E.I.) and Co., Aiken, SC (USA). Savannah River Lab.
• DOE Contract Number: AC09-76SR00001
• OSTI ID: 6928639
• Report Number(s): DP-MS-86-178; CONF-870314-1; ON: DE87002653
• Country of Publication: United States
• Language: English

Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal & Storage
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CARBON STEELS
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHEMISTRY
CONTAINERS
CORROSION
CORROSION INHIBITORS
ELECTROCHEMISTRY
HIGH-LEVEL RADIOACTIVE WASTES
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
PITTING CORROSION
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
SLUDGES
STEELS
TANKS
WASTES