Radiation safety, radioactive waste, spent nuclear fuel, decommissioning department
The prospects for the development of the nuclear power in the world are determined by three global environmental problems. The first is that at present it is not possible to completely (guaranteed) eliminate severe accidents beyond design basis at nuclear power plants. This dictates the need for constant readiness to prevent and respond to possible emergencies both at the level of the organization operating the nuclear power plant and at the governmental level.
The second problem is the management of radioactive waste (RW), especially high-level waste (HLW). This problem has not yet been solved in any country in the world, because HLW is a prohibitive level of activity of biologically significant radionuclides with a very long half-life, which causes their potential radiological danger for many thousands of years to come. Such waste is supposed to be buried at deep burial sites with preliminary exposure (if necessary) in order to reduce heat generation. It is clear that there is no need to talk about the construction of a burial site, the protective barriers of which will ensure the retention of radionuclides at such a time horizon. Therefore, with regard to HLW, recommendations are given for burial in deep geological systems, in rock formations, at a large depth (over 100 meters for solid and over several hundred meters for liquid radioactive waste). But this also does not last forever: the rocks are destroyed, sooner or later, activity can manifest itself in groundwater and find a way to a person through aquifers. That is why one should not underestimate the problem of disposal of low- and medium-active long-lived waste. For an adequate choice of a safe method for RW disposal, it is necessary to ensure their reliable characterization, which is difficult today due to the complex radionuclide composition and gaps in regulating the classification of waste for disposal. This challenge also requires a speedy solution.
The third problem, which is yet to be solved, is the management of spent nuclear fuel (SNF).
Helping Rosenergoatom Joint-Stock Company solve three of the above problems, as well as other important challenges, the VNIIIAES operates a department for radiation safety, radioactive waste, SNF, and decommissioning.
Emergency preparedness and response
Scientific, methodological and technical support of the operating organization in the field of emergency preparedness and response is one of the main directions of our work.
A key element of the Company’s emergency preparedness system, as it operates nuclear power plants, is the NPP Emergency Assistance Team (NEAT).
VNIIAES is one of the 14 NEAT technical support centers (TSC), the goal of which is to quickly provide scientific, technical and expert support to the NEAT group in the event of an accident at a nuclear power plant. For more than 20 years, VNIIAES has been involved in the preparation, conduct and analysis of the results of all trainings with the participation of the NEAT group and comprehensive emergency response exercises involving local authorities, as well as all the forces and means of ministries and departments aimed at eliminating the emergency situation at nuclear power plants. All this is to improve the Company’s preparedness as an operating organization for emergency situations.
In recent years, VNIIAES has been participating in another very important project providing scientific and methodological support to the recently created Regional Crisis Center of WANO NPP MC (RCC). The RCC was set up in 2012 as one of the responses to the accident at the Fukushima-1 Japanese nuclear power plant (2011) with the aim of promptly and reliably distributing information on safety-related topics between WANO MC members and establishing international assistance mechanisms and scientific and technical support for NPP operating organizations in the event of an accident.
A lot of attention is paid to improving the quality of radiation monitoring, developing and maintaining up to date methodologies and software.
The process of improving the regulation and control of emissions and discharges really brought up very serious questions, in some cases this is not just a clarification, but a revision of views. Therefore, an important task today is the transition to a completely new system of regulation of emissions and discharges of radioactive substances into the environment in full.
The transition to new standards, the expansion of the list of radionuclides (primarily to include tritium and radiocarbon), the nomenclature of sources is basically a theoretical and calculation task and not the most difficult one. But after its implementation, it is necessary to confirm the compliance of emissions and discharges with the established regulatory requirements. This entails a lot of work to review and improve the standard system of radiation monitoring of emissions and discharges. As a result of this large-scale work, there will indeed be a transition to a new generation of both standards and a system for controlling emissions and discharges into the environment. This task should be solved taking into account the Decree of the Government of the Russian Federation dated 6/16/2016 No. 422, which established the requirements for the development, coordination with Rostekhnadzor and the inclusion of methods for calculating emissions of radioactive substances from stationary sources in the list of the Ministry of Natural Resources of Russia. VNIIAES informed the Company’s nuclear power plants of its readiness to develop such techniques. Few people are interested in the process of operating a nuclear power plant, but the radiation impact of a nuclear power plant on the population and its compliance with established regulatory requirements is a very important issue for the public.
The solution of this problem is moving to the next level, and VNIIAES is playing an important role in the transition to the new-generation radiation control systems for emissions and discharges.
It should be noted that a wide range of issues addressed by VNIIAES is associated with the development and implementation of radiation monitoring techniques at nuclear power plants, with approximately 80% of the techniques introduced at nuclear power plants are the result of our institutes’ initiatives.
Another important problem should be mentioned. A fundamental characteristic of a nuclear power plant is the risk of potential (taking into account possible disturbances in normal operation) exposure of personnel and the public during plant operation. The threshold of such a risk are established in NRB-99/2009. At present, there is no methodology for calculating the risk of potential exposure, which does not allow an assessment of the conformity of nuclear power plants with the specified regulatory requirements. VNIIAES plans to pay close attention to this issue.
A topical subject nowadays is the optimization of radiation monitoring in the areas where nuclear power plants are located. Compared to the beginning of the 1980s, there was a powerful suppression of emissions and discharges of radioactive substances from nuclear power plants into the environment; in general, they decreased by two orders of magnitude, primarily due to an increase in the quality of production of nuclear fuel, timely removal of leaky fuel assemblies from the reactor core fuel elements, the use of modern cleaning systems, improving safety culture. Under conditions of normal nuclear power plant operation, the current production radiation monitoring in the environment seems excessive, even taking into account the socio-political factor (this factor is always present when it comes to radiation!). The Company needs an appropriate evidence base, and VNIIAES, through the development of reliable control methods, helps in its creation.
NPP physical barriers control
As we all know, the safety of nuclear plants is ensured by the consistent implementation of the defense-in-depth principle. For each of its barriers, the limits of safe operation and operational limits are established, including the radiation parameters.
VNIIAES is one of the leaders in the development and equipping the Russian and foreign nuclear power plants with modern tools, methodologies and software for monitoring the integrity of safety barriers, in particular, leakages of steam generators and the tightness of nuclear fuel rods, as well as emissions and discharges of radioactive substances into the environment.
It is worth noting that the safety limits of physical barriers were mainly set during the last century, at the initial stage of operation of nuclear power plants. The application of these limits at present requires scientific justification and revision due to the fact that new types of nuclear fuel have been introduced and are being introduced, a transition has been made to long fuel cycles, power blocks are operated at increased capacity or at maneuver modes. The institute is ready to solve these problems. The most important area is the diagnostics of the state of nuclear fuel during operation. At the institute, methods are being developed to determine the mechanisms and causes of damage to fuel elements based on radiation monitoring methods and analysis of operating conditions, manufacturing quality and design characteristics of nuclear fuel.
Nowadays, environmental management is universally recognized as a modern effective mechanism for solving environmental problems.
Since 2004, VNIIAES has been providing scientific and methodological support to the Company and operating nuclear power plants for the development, implementation and improvement of the environmental management system (EMS) in accordance with the requirements of international and national standards ISO 14001 (GOST R ISO 14001). Both the basic documents (environmental policy, organization standards, lists of environmental aspects, etc.) and the working documentation of the EMS units have been developed.
As the new version of the international standard ISO 14001: 2015 and the national standard GOST R ISO 14001-2016 were released in 2015, VNIIAES has been providing services to a number of nuclear power plants (the Balakovo, the Kalinin and the Novovoronezh NPPs) for bringing the EMS into compliance with the new requirements of the process approach, including introduction of risk-based thinking. For the successful functioning of the EMS in the Company, it is planned to conduct an analysis of the EMS functioning at each nuclear power plant and prepare recommendations on making the necessary changes to the relevant organizational standards, including the process passports.
Radioactive waste management
VNIIAES analyzes and generalizes the experience of operating radioactive waste management systems, develops and implements effective technologies and radioactive waste management systems, relevant methods and technological regulations. The Institute, together with the STC NRS of Rostekhnadzor, substantiated and published proposals on a fundamental revision of the certification system and classification of disposed solid RW for burial.
One of our major ongoing activities is an R&D on the development of a module for liquid radioactive waste processing with the production of conditioned radioactive waste that meets the criteria for disposal acceptability.
Another VNIIAES priority in the field of radioactive waste management is the development of technologies and solutions for solid radioactive waste management and handling metal contaminated with radioactive substances. So, the institute has developed the in-vessel devices fragmentation project for the Novovoronezh NPP’s 2nd power block.
VNIIAES has developed project documentation for a temporary modular type site for the processing and conditioning of solid radioactive waste (SRW) generated during decommissioning of nuclear power facilities and the rehabilitation of contaminated territories (RCT) using technologies and equipment for sorting, decontamination, fragmentation, volume reduction, RW cementing at the operating organizations sites - customers requesting the decommissioning and the RCT activities. In order to improve the management of radioactive waste at the operating NPP power blocks, VNIIAES developed the initial technical requirements for plants for the extraction of medium- and high-activity waste, which enables modernization of the radioactive waste management system by introducing automated SRW recovery plants.
VNIIAES has developed a significant part of the methodological support for radiation monitoring of radioactive waste at Russian nuclear power plants. To optimize radiation monitoring of radioactive waste, the radionuclide vector methodology is used. With the active involvement of the Institute, it was introduced at the Kalinin, Leningrad, Novovoronezh, Smolensk NPPs and the Experimental Demonstration Engineering Center (ODEC) for decommissioning NPP units; by the end of 2019, this technology is planned to be introduced at the Rostov and Belarusian NPPs.