Cesium and Strontium Contamination of Nuclear Plant Stainless Steel: Implications for Decommissioning and Waste Minimization

Abstract

Stainless steels can become contaminated with radionuclides at nuclear sites. Their disposal as radioactive waste would be costly. If the nature of steel contamination could be understood, effective decontamination strategies could be designed and implemented during nuclear site decommissioning in an effort to release the steels from regulatory control. Here, batch uptake experiments have been used to understand Sr and Cs (fission product radionuclides) uptake onto AISI Type 304 stainless steel under conditions representative of spent nuclear fuel storage (alkaline ponds) and PUREX nuclear fuel reprocessing (HNO3). Solution (ICP-MS) and surface measurements (GD-OES depth profiling, TOF-SIMS, and XPS) and kinetic modeling of Sr and Cs removal from solution were used to characterize their uptake onto the steel and define the chemical composition and structure of the passive layer formed on the steel surfaces. Under passivating conditions (when the steel was exposed to solutions representative of alkaline ponds and 3 and 6 M HNO3), Sr and Cs were maintained at the steel surface by sorption/selective incorporation into the Cr-rich passive film. In 12 M HNO3, corrosion and severe intergranular attack led to Sr diffusion into the passive layer and steel bulk. In HNO3, Sr and Cs accumulation was also commensurate with corrosion product (Fe and Cr) readsorption, and in the 12 M HNO3 system, XPS documented the presence of Sr and Cs chromates.

Highly selective cesium(I) capture under acidic conditions by a layered sulfide

“…The strongly acidic high-level-liquid-wastes (HLLWs) resulting from the recovery of uranium and plutonium from spent fuel by the PUREX process contain 137 Cs in ionic form 1 , 5 – 7 . The key for the disposal of HLLWs is the removal of strongly radioactive ions (such as 137 Cs) to reduce their radioactivity level 6 .…”

Strippable Polymeric Nanocomposites Comprising “Green” Chelates, for the Removal of Heavy Metals and Radionuclides

“…For the controlled contamination process, we tried to reproduce cesium contamination at levels representative of those found in the nuclear industry, namely we started with 5 mM (C1) of Cs 2 SO 4 aqueous solution, a similar concentration with those mentioned in the literature [ 7 , 44 ]. After being subjected to the controlled contamination process, stainless-steel samples were further analyzed by the EDS technique, the mean values, and standard deviations for the determined and calculated values are reported in Table 4 .…”

“…It is the main raw material for nuclear bombs and nuclear power plants. Cesium and strontium are high-yield fission products that are present in significant amounts in fuel pond waters and reprocessing stream liquors [ 7 ]. Radioactive contamination can occur as a result of working with radioisotopes, an accident, or even a terrorist attack [ 8 ].…”

Radioactive decay of $$\mathrm {{}^{90}Sr}$$ in cement: a non-equilibrium first-principles investigation

“…Within this context, it is also of great importance to study the fate of 137 Cs in cement, which has a great propensity to leach [29]. Also of major interest is to study the effect of the decay of 90 Sr and 137 Cs in stainless steel, which is the other structural material used as a barrier to contain radioactive waste [30].…”