Study on Reduction of Liquid Waste From Reprocessing Plant by Electrolysis Process

2001 ◽  
Author(s):  
M. Shibuya ◽  
Y. Suzuki ◽  
H. Shimizu ◽  
M. Inoue ◽  
H. Kaneki ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Sodium Nitrate ◽  
Pilot Plant ◽  
Liquid Waste ◽  
Gas Composition ◽  
Storage Unit ◽  
Low Level ◽  
Engineering Study ◽  
Fundamental Research ◽  
Reprocessing Plant

Abstract The reduction of radioactive waste volume is an important issue for the management of the nuclear fuel cycle. The purpose of this study is to create a technique to drastically reduce low-level liquid waste generated by a spent fuel reprocessing plant employing PUREX technology. In the PUREX plant, NOx gas is used as an oxidizing reagent for adjustment of the Pu valence in the Pu purification stage. The spent NOx gas is recovered as nitric acid and a certain amount of recovered nitric acid becomes low-level waste (LLW). As NOx gas is produced by the chemical reaction of nitric acid and sodium nitrite, a considerable quantity of non-radioactive sodium nitrate solution is discharged. From the standpoint of the impact on the environment, this discharge must be reduced. The objective of this research is to develop an electrolysis process by which NOx gas is directly produced from recovered nitric acid. Using this technology, the low-level sodium nitrate waste can be reduced and the nonradioactive sodium nitrate waste from the present NOx production process can be entirely eliminated. The study was performed in the following two steps: Phase 1: Fundamental research; Phase 2: Engineering study. Fundamental research: A study on the conditions of nitric acid decomposition by electrolysis was performed. The composition of NO and NO2 and its quantity are determined by electrolyte concentration, cathode material and current density. Catholyte reduced electrochemically is in a state of chemical equilibrium expressed by NO, NO2 (N2O4), HNO2, HNO3 and H2O. Nitric acid concentration, temperature and partial pressure of NOx are important process parameters since NOx generation current efficiency and NOx gas composition are dependent on a chemical equilibrium. Engineering study: The pilot plant was designed and constructed. The process configuration of the pilot plant is the same as that of the anticipated actual plant and its NOx generation capacity is one eighth of the actual plant. The plant mainly consists of electrolysis unit, NOx compression and storage unit, sodium nitrite oxidation unit, nitric acid distillation unit, and NOx recovery and off-gas treatment unit. NOx gas and HNO2 are generated as a result of nitric acid reduction in the electrolysis unit. NOx gas is transported under negative pressure to the compression/storage unit by a compressor and is stored in tanks under high pressure. After adjustment of gas composition by O2 supply, NOx gas is fed to the user process in the case of an actual plant. In the pilot test plant, NOx gas is transported to the nitric acid recovery step, in which NOx gas is recovered as nitric acid and reused in the pilot plant. As a result of operation of the pilot plant, the process performance, equipment performance, and long-term operation stability were proven. It was confirmed through the pilot plant operation that this technology was immediately applicable to a PUREX reprocessing plant.

Separation and Recovery of Sodium Nitrate From Low-Level Radioactive Liquid Waste by Electrodialysis

2010 ◽  
Author(s):  
Yoshihiro Meguro ◽  
Atsushi Kato ◽  
Yoko Watanabe ◽  
Kuniaki Takahashi
Keyword(s):  
Sodium Nitrate ◽  
Nitrate Solution ◽  
Liquid Waste ◽  
Sodium Ion ◽  
High Concentration ◽  
Radioactive Liquid Waste ◽  
Nitrate Ion ◽  
Low Level ◽  
Sodium Nitrate Solution ◽  
Exchange Membrane

An advanced method, in which electrodialysis separation of sodium nitrate and decomposition of nitrate ion are combined, has been developed to remove nitrate ion from low-level radioactive liquid wastes including nitrate salts of high concentration. In the electrodialysis separation, the sodium nitrate was recovered as nitric acid and sodium hydroxide. When they are reused, it is necessary to reduce the quantity of impurities getting mixed with them from the waste fluid as much as possible. In this study, therefore, a cation exchange membrane with permselectivity for sodium ion and an anion exchange membrane with permselectivity for monovalent anion were employed. Using these membranes sodium and nitrate ions were effectively removed form a sodium nitrate solution of high concentration. And also it was confirmed that sodium ion was successfully separated from cesium and strontium ions and that nitrate ion was separated from sulfate and phosphate ions.

Quantification of Transferring and Adhering for Pd, Mo, Te, Sb, Ru, Re, Cs and I During the Evaporation Under Vacuum and at Atmospheric Pressure

2003 ◽  
Author(s):  
K. Ito ◽  
T. Takata ◽  
M. Kamiya
Keyword(s):  
Nitric Acid ◽  
Nuclear Waste ◽  
Sodium Nitrate ◽  
Atmospheric Pressure ◽  
Liquid Waste ◽  
Waste Recycling ◽  
Nuclear Fuel Reprocessing ◽  
Recycling Of Wastes ◽  
Fuel Reprocessing ◽  
Nitrate Solutions

In order to modify current nuclear fuel reprocessing plants on the basis of a more sophisticated, economical, and safer nuclear waste recycling system, the production of low-level radioactive wastes must be reduced and the recycling of wastes must become more efficient. To simulate liquid waste recycling operations, evaporators under vacuum and at atmospheric pressure were used to determine adhering and transferring rates for Pd, Mo, Te, Sb, Ru, Re, Cs and I in the nitric acid and sodium nitrate solutions. In the evaporation from the HNO3 and NaNO3 solutions containing precipitate PdI2, the percentage values for materials adhering on the inside of lid at vacuum pressure were 0.01 ∼ 0.1%/m2, however at atmospheric pressure the values were 0.001 ∼ 0.01%/m2. Adhering percentage values on the condenser were 0.0001 ∼ 0.001%/m2 for the vacuum and atmospheric pressure systems. The transferred percentages into the distillate for Pd, Mo, Te, Sb, Ru, Re, and Cs were 0.0001 ∼ 0.001% in the HNO3 and NaNO3 solutions for the vacuum and atmospheric pressure systems, and those of I were about 10% for HNO3 system at atmospheric pressure, 2∼7% for HNO3 system under vacuum, 0.01∼0.1% for NaNO3 system under vacuum. Reducing rates for the treated solution were one third of feeding solutions in the evaporation under vacuum and at atmospheric pressure.

Development of Separation Technique of Sodium Nitrate From Low-Level Radioactive Liquid Waste Using Electrodialysis With Selective Ion-Exchange Membranes

2013 ◽  
Author(s):  
Keita Irisawa ◽  
Akinori Nakagawa ◽  
Takashi Onizawa ◽  
Takafumi Kogawara ◽  
Keiji Hanada ◽  
...  
Keyword(s):  
Sodium Nitrate ◽  
Liquid Waste ◽  
High Concentration ◽  
Radioactive Liquid Waste ◽  
Nitrate Ion ◽  
Advanced Method ◽  
Low Level ◽  
Fundamental Investigation ◽  
Experimental Parameters ◽  
Liquid Wastes

An advanced method, in which electrodialysis separation of sodium nitrate and decomposition of nitrate ion are combined, has been developed to remove nitrate ion from low-level radioactive liquid wastes including nitrate salts of high concentration. An engineering scale apparatus with two electrodialytic devices, in which the sodium and nitrate ions were separately removed by each device, was produced on the basis of the results of fundamental investigation previously reported, and the performance of the apparatus was tested. Both the ions were successfully removed at the same time, though these ions were separately transferred using two electrodialytic devices. And also effect of several experimental parameters such as current and temperature on current efficiency of both the ions of each device was investigated.

Bituminization of Low-Level Liquid Waste

1981 ◽  
pp. 219-226
Author(s):  
Teruo Tokubuchi ◽  
Shigeki Kitajima ◽  
Hiroshi Kuribayashi ◽  
Takuro Yagi ◽  
Tomoyoshi Kagawa
Keyword(s):  
Liquid Waste ◽  
Low Level

scholarly journals Fundamentals of the methods for investigating crimes related to falsification of evidence in administrative cases

2021 ◽  
pp. 177-183
Author(s):  
V. P. Popov
Keyword(s):  
Russian Federation ◽  
Financial Support ◽  
Criminal Code ◽  
Research Project ◽  
Low Level ◽  
Administrative Procedure ◽  
Fundamental Research ◽  
The Russian Federation

Despite the adoption in 2015 of the Code of Administrative Procedure of the Russian Federation, liability for falsification of evidence in administrative cases was established only in 2017. Part 1 of Article 303 of the Criminal Code of the Russian Federation, which provides for liability for falsification of evidence in administrative cases, has existed for more than three years, but the number of detected crimes is small. One of the main reasons is the low level of criminalistic assurance for the investigation of crimes of this category. This article lays the fundamentals for the development of a methods for investigating falsification of evidence in administrative cases. This study is carried out with the financial support of the Russian Foundation for Fundamental Research in the framework of the research project № 18-29-14084. 

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