Assessing the efficiency of a “buried wall” barrier in the establishment of near-surface long-term storage and disposal facilities for RW

The article evaluates the impact of a “buried wall” barrier on the long-term safety during the long-term storage1 or in-situ disposal of nuclear legacy facilities, in particular, industrial reservoirs, as well as during the development of near-surface disposal facilities for radioactive waste (RWDF). For assessment purposes, filtration and mass transfer processes have been numerically modelled in the GeRa code based on a case study of a reference near-surface facility. The study explores in which way the available covering screen affects the dynamics of contaminant spread. It evaluates the sensitivity of the results to the dispersion parameter commonly characterized by a high degree of uncertainty.

Refinment of a decontamination technology for radioactively contaminated equipment

This article analyzes the data on chemical decontamination methods dealing with radioactively contaminated surfaces. It considers the composition of solutions most commonly used for decontamination purposes. Numerical data are presented to illustrate the effectiveness of various decontamination methods. The paper considers an experiment on the decontamination of stainless steel samples with water following a cavitation treatment. The study reveals a dependence between the decontamination efficiency and the treatment time of the contaminated surface with a decontamination solution based on cavitation-activated water, which appears to be comparable with the results of the one involving an alkaline solution.

Experience in the development and operation of facilities for primary characterization of waste from nuclear facilities

The article focuses on methodological and hardware support of radioactive waste characterization, including the one associated with radiation characteristics of materials measured to support the decision-making on its release from regulatory control. The study provides an assessment of uncertainties and their influence on the measurement results. It presents the experience of the Czech company JSC VF in the development of automated installations allowing to address this problem with some examples of such installations operating in various countries being provided.

The Radiation Situation in the Area of the Meteorit-5 Peaceful Nuclear Explosion

Pursuant to relevant provision of the Federal Law No. 190-FZ On Radioactive Waste Management and Amendments to Certain Legislative Acts of the Russian Federation of July 11, 2011, radioactive waste generated due to the peaceful uses of nuclear charges has been attributed to the non-retrievable radioactive waste (RW) category. Accordingly, relevant RW subsoil areas are currently considered as facilities holding non-retrievable RW with periodic radiation monitoring that should be performed and certain measures provided to ensure the long-term safety of the population. The article presents the results of a radiation survey performed in 2019 for the site with non-retrievable RW inventory generated from the Meteorite-5 peaceful nuclear explosion.

Method for Radioactive Waste Disposal in Underground Mines

This paper presents the key parameters associated with the disposal method used to dispose of radioactive waste (RW) of Class 2 and 3 in abandoned underground mines of PIMCU site assuming additional isolation of RW containers, adjustment of bedrock geomechanical properties and compliance with regulatory requirements. The paper briefly analyzes international practices focused on RW disposal in natural and artificial underground cavities. It provides a comparison between the forecasted volumes of RW generation at the enterprises of the State Corporation Rosatom and the available underground disposal capacity at PIMCU site. It presents the main characteristics of a paste filling manufactured based on materials from uranium ore processing and used as an insulating filler inside the vaults. The paper summarizes the results of operations on rock mass reinforcement based on an injection method. It indicates the key advantages of the proposed method.

On the Challenge Associated with the Final Stage of Irradiated Graphite Management from Water-Graphite NPP Reactor Units

The paper discusses engineering, economic and legislative aspects influencing the ways of addressing the problem associated with the final stage of irradiated graphite management from water-graphite NPP reactor units in Russia. It presents some calculated and experimental data demonstrating the feasibility of introducing some corrective changes to the legislative and regulatory framework existing in the Russian Federation to enable near-surface disposal of irradiated graphite from power reactors.

Silver recovery from radioactive waste generated due to the disposition of silver-containing products

The studies performed resulted in the development of a method enabling silver recovery from radioactively contaminated silver-containing products. This method includes the following stages: preliminary decontamination of products, dissolution of silver product fragments in a nitric acid solution, production of finely dispersed silver by displacement of silver metal with copper, submerged melting of finely dispersed silver at a temperature of at least 960°С. To reduce the operating costs, evaluated was the feasibility of silver recovery from its compounds (chloride, sulphate and oxide).

Underground Research Laboratory: Overcoming Uncertainties in the Assessment of Seismic Conditions for the Yeniseiskiy Site

The article presents the basic principles and an algorithm allowing to arrange a seismological monitoring system for the Yeniseiskiy site selected for deep geological disposal of high-level waste. It describes the seismological monitoring system developed by NO RAO in 2018 also briefly considering the seismotectonic conditions of the area. The paper describes the process that has been followed to select the corresponding sites and equipment layouts in the areas fitted with seismological monitoring stations with relevant instrumental characteristics being provided. It shows that considering the current stage of research, higher sensitivity was provided in the area as compared to the one associated with available regional seismological observations. It demonstrates the efficiency of the built-up monitoring system with its sensitivity assessment provided both based on the calculated model and under real conditions. The long-term safety assessment performed for such a facility relies upon many factors with the seismic hazard level within the area of the monitored facility also taken into consideration. To provide most reliable evaluation of seismic parameters, continuous seismological monitoring should be performed over a several years’ period along with the sensitivity assessment of the selected monitoring system. The seismological monitoring system should focus not only on the general study of the monitored territory, but also on the areas assumed as zones of most probable seismic event occurrence, i.e. areas involving tectonic faults. The relevance of this task has been repeatedly emphasized in the course of multiple discussions on this issue featuring the representatives from SC Rosatom and the Scientific and Engineering Centre for Nuclear and Radiation Safety. The monitoring system fitted within the repository area meets relevant regulatory requirements. In accordance with the existing requirements, to reduce the uncertainties in the seismic hazard assessment of the territory, the implementation of certain measures was recommended during further development of the local seismological monitoring network to identify and assess the potential of hazardous geodynamic zones.