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Swiss nuclear power and the case for long-term operation
Designed for 40 years but built to last far longer, Switzerland’s nuclear power plants have all entered long-term operation. Yet age alone says little about safety or performance. Through continuous upgrades, strict regulatory oversight, and extensive aging management, the country’s reactors are being prepared for decades of continued operation, in line with international practice.
Yongjun Zhu, Rongzhou Jiao
Nuclear Technology | Volume 108 | Number 3 | December 1994 | Pages 361-369
Technical Paper | Enrichment and Reprocessing System | doi.org/10.13182/NT94-A35018
Articles are hosted by Taylor and Francis Online.
Mixed trialkylphosphine oxide (TRPO) (alkyl is C6-C8) was chosen as the extractant for the removal of uranium, neptunium, plutonium, and americium from highly active waste (HAW) in China. Composition and properties of the extractant and process chemistry are based on 30 vol% TRPO-kerosene as solvent. Hexa-and tetravalent actinides are highly extractable in 30 vol% TRPO extraction from acidic HAW, and trivalent americium (curium) can be extracted effectively from HAW with a nitric acid concentration of ∼1 mol/ℓ Actinides extracted can be stripped successively by 5.5 mol/ℓ HNO3, 0.6 mol/ℓ H2C2O4, and 5% Na2CO3 into americium + rare earth, neptunium + plutonium, and uranium fractions, respectively. The loading capacity of TRPO solvent is higher than that of bifunctional organophosphorus extractants, and the radiolytic stability of TRPO is higher than that of tributyl phosphate (TBP) and bis(2-ethyl hexyl)phosphoric acid. The extraction and stripping rate of TRPO is high enough to be compatible with the centrifugal contactors. Optimized process parameters of multistage countercurrent extraction and stripping and results of experimental verification are established. In both a batch experiment with simulated nuclear power plant (NPP) spent-fuel Purex HAW and a continuous experiment with real NPP spent-fuel Purex HAW, 99.9% recovery of actinides was achieved. The modification of the solvent system with TBP to fit the conditions in the chemical pretreatment of defense HAW is considered.
