Relevancy
The management of spent nuclear fuel (SNF) remains one of the most complex and unresolved challenges in nuclear energy, particularly during the decommissioning of nuclear facilities. Under these conditions, it is essential to ensure the safe long-term storage, processing, or final disposal of accumulated nuclear materials in compliance with nuclear and radiation safety requirements, as well as international non-proliferation obligations.
This issue is of particular significance for the Republic of Kazakhstan due to the decommissioning of the BN-350 fast neutron reactor, which operated in Aktau from 1973 to 1999. The SNF from this reactor contains weapons-grade plutonium and highly enriched uranium, which imposes heightened requirements for physical protection and nuclear material control. After the reactor was shut down, all BN-350 SNF was removed from the Aktau site and placed in long-term storage at the Baykal-1 research reactor complex of the National Nuclear Center of the Republic of Kazakhstan (NNC RK). The fuel is packaged in sealed canisters and stored in TUK-123 transport casks.
According to the recommendations of the International Atomic Energy Agency (IAEA), long-term storage is considered only as a temporary stage in the management of SNF. Final solutions are expected to involve either fuel reprocessing or ultimate disposal, ensuring the long-term isolation of radioactive materials from the environment.
An important aspect of this issue is the limited service life of the storage systems in use. TUK-123 casks are designed for safe operation for 50 years; the loading of BN-350 SNF began in 2008, and a significant portion of this period has already elapsed. This necessitates a timely justification of the further strategy for managing this fuel. Consequently, comprehensive studies are required, including an analysis of SNF management technologies applied internationally, as well as computational safety assessments for its long-term storage. The results obtained will provide a basis for selecting the most optimal and safe approach for the further management of BN-350 SNF.
The relevance of this research is also linked to the prospects for the development of nuclear energy in the Republic of Kazakhstan, where the management of SNF and radioactive waste takes on strategic significance in establishing a national system for handling nuclear materials.
Program Objective
To develop recommendations for the optimal management of SNF from the BN-350 reactor, ensuring compliance with the legislation of the Republic of Kazakhstan and international agreements, as well as meeting requirements for nuclear, radiation, and physical protection safety, and non-proliferation regulations in handling fissile materials.
Expected Outcomes
Direct Results:
Scientific Direction 1. “Study of international practices in handling spent nuclear fuel (SNF) from power reactors”:
- Analytical materials have been prepared on the methods of spent nuclear fuel (SNF) management applied in international practice;
- Technical and economic feasibility assessments have been conducted for the considered management methods.
Scientific Direction 2. “Assessment of the current state of SNF from BN-350 reactor”:
- A set of initial data has been obtained for conducting nuclear and radiation safety calculations, including accident scenarios not previously considered in the safety analysis of BN-350 SNF management;
- Computational models have been developed for safety analysis;
- Quantitative results of safety calculation studies for SNF handling have been obtained;
- The energy potential of the BN-350 reactor spent fuel has been estimated through calculations.
Scientific Direction 3 “Study of SNF handling methods for BN-350 reactor”:
- A list of potentially applicable SNF management methods has been prepared;
- A methodology for the comparative evaluation of different SNF handling methods has been developed;
- Recommendations have been formulated for selecting the most optimal method for managing BN-350 spent nuclear fuel.
Final Outcome:
Scientific Direction 1. “Study of international practices in handling spent nuclear fuel (SNF) from power reactors”
A comprehensive dataset on international SNF management practices, including key technical and economic indicators, will be obtained. This dataset will serve as the primary source of information for the analytical team.
Economic impact: The data will provide a basis for selecting the most effective method for managing BN-350 SNF.
Environmental impact: The data will support the choice of a method for SNF management that ensures safety with respect to environmental protection.
Social impact: The project will enhance the overall expertise of specialists in Kazakhstan’s nuclear energy sector regarding nuclear waste management and will provide impetus for the further development of scientific and applied research in this field.
Scientific Direction 2. “Assessment of the current state of SNF from BN-350 reactor”:
A comprehensive set of measurement and computational studies has been conducted to confirm the safety characteristics of the design parameters and storage conditions for BN-350 SNF. Data have been obtained to support the analytical assessment of methods for the further management of BN-350 SNF.
Economic impact: The data provide up-to-date information on the current condition of BN-350 SNF and storage containers, enabling the forecasting of costs associated with maintaining safe operating conditions.
Environmental impact: The data are based on measurements of the radiological impact of BN-350 SNF on the environment under long-term storage in transport casks.
Social impact: The project demonstrates continuous monitoring and safety assurance for both the population and the environment in the management of SNF.
Parameters of spent nuclear fuel will be obtained during both dry and wet storage; recommendations will be developed for the selection of nuclear power plant radioactive waste management technologies; and data will be collected to assess the material durability of containers for long-term SNF storage.
Scientific Direction 3. “Study of SNF handling methods for BN-350 reactor”:
Recommendations will be developed for selecting the most effective and optimal method for managing BN-350 SNF. The research results will support informed decision-making regarding the next steps in BN-350 SNF management.
Economic impact: The research will provide new data that can be used to optimize financial expenditures on BN-350 SNF management, which are currently directed toward maintaining the current state of long-term storage.
Environmental impact: The results will contribute to reducing potential radiological risks associated with the concept of interim long-term SNF storage, designed for the established service life of the storage containers.
Social impact: Implementing the proposed SNF management measures will help reduce societal and psychological concerns by mitigating radiation safety risks to the population and the environment. Furthermore, within the framework of the country’s nuclear energy program, concrete actions regarding BN-350 SNF management will demonstrate to the public a systematic approach to nuclear waste management, thereby increasing overall public acceptance of nuclear energy.
Main Results of the Research Work
During the implementation of the program “Research to Substantiate the Selection of Effective and Optimal Methods and Technologies for Managing Spent Nuclear Fuel from the BN-350 Fast Neutron Reactor”, the following key results have been achieved:
2024
Scientific Direction 1. “Study of international practices in handling spent nuclear fuel (SNF) from power reactors”:
As part of the review and description of SNF storage methods, studies of international practices for managing SNF from power reactors have been conducted. Based on the results of the analytical review, methods and technologies for both wet and dry SNF storage applied worldwide were examined (Technical Note “Review and Description of Spent Fuel Storage Methods” No. 12-230-02/201 dated 04.11.2024). For wet SNF storage, both near-reactor pool storage and off-reactor facility storage technologies were considered. For dry SNF storage, container and vault storage technologies were analyzed. Wet storage is a mandatory stage following SNF removal from the reactor, during which decay heat is reduced and the most active short-lived radionuclides decay. In dry storage technologies, the most widely used methods are storage in vaults and containers. An analysis of the main advantages and disadvantages of SNF storage technologies was carried out, including an assessment of the economic efficiency of wet and dry storage. The primary advantage of storage lies in the well-developed technological experience and relative technological safety. Storage as a strategy and technology is applied in all countries developing nuclear energy. The main disadvantage of storage is its “incompleteness” – this approach does not provide a final solution for the isolation of SNF and requires continuously increasing costs without a clear prospect of termination. Economic assessments indicate that dry SNF storage is more cost-effective.
Scientific Direction 2. “Assessment of the current state of SNF from BN-350 reactor”:
As part of the assessment of the overall condition and characteristics of the structural components of TUK-123 following the long-term storage of BN-350 SNF, the following work has been performed: 1) Radiation measurements – including the maximum equivalent dose rate, radioactive contamination on the outer surface of the cask, and removable and fixed contamination by alpha and beta emitters; 2) Leak-tightness testing of the TUK-123 cask connections; 3) Temperature measurements of the cask outer surface containing SNF, taking into account solar heating (Acts: “Determination of TUK Outer Surface Temperature at the Baikal-1 SNF Long-Term Storage Facility” No. 37-361-01/598 dated 23.10.2024; “Leak-Tightness Verification of TUK-123 at the Baykal-1 SNF Facility” No. 37-361-01/594 dated 21.10.2024; “Determination of Gamma Dose Rate on the TUK Surface at the Baikal-1 SNF Facility” No. 37-441-01/597 dated 23.10.2024). Based on operational experience from October 2010 to the present, no deviations beyond permissible limits have been detected in the key operational and technical characteristics, confirming the compliance of the TUK-123 cask with the design safety parameters and, overall, validating the safety of the dry storage concept for BN-350 SNF in dual-purpose containers. A dataset has been compiled, including information on the structural characteristics of fuel assemblies, absorber assemblies, fuel assembly canisters, and storage sets within the transport cask system. Additionally, data on the physical and mechanical properties of fuel assembly components after reactor irradiation, initial fuel enrichment, maximum burnup, isotopic composition, residual heat generation, and the activity of major fission products and activation nuclides in the spent FA have been prepared. This dataset will be used for computational studies to substantiate the safety of long-term storage of BN-350 SNF in dual-purpose containers.
2025
Scientific Direction 1. “Study of international practices in handling spent nuclear fuel (SNF) from power reactors”:
An analysis of international practices for the main spent nuclear fuel (SNF) reprocessing methods has been conducted (Technical Note “Review and Description of Spent Nuclear Fuel Reprocessing Methods,” No. 24-405-03/1067vn dated 25.06.2025). The following methods were considered: 1. Hydrometallurgical methods, the most widely used SNF reprocessing techniques, based on dissolving fuel in an aqueous acid solution followed by chemical separation of components (PUREX process – Plutonium Uranium Reduction EXtraction); 2. Pyrochemical (dry) methods, based on high-temperature processes without the use of aqueous solutions; 3. Volatilization (fluorination), a process in which SNF components are converted into volatile fluorides at high temperatures and then separated according to condensation temperatures. Based on the data obtained, an analytical assessment was carried out to identify the main advantages and disadvantages of each technology in terms of process complexity, the degree of purification of final products, and the generation and management of radioactive waste.
A study of global approaches to SNF disposal has also been conducted (Technical Note “Review and Description of Spent Nuclear Fuel Disposal Methods,” No. 24-405-03/1585vn dated 01.10.2025). Methods considered include disposal in deep geological formations and boreholes. Analytical work was performed to determine the main advantages and disadvantages of these disposal approaches. Conceptual solutions for disposal technology were developed based on the results obtained.
As part of this work, two articles were published. In a journal indexed in Scopus & WoS:
In a journal recommended by CQASHE:
Scientific Direction 2. “Assessment of the current state of SNF from BN-350 reactor”:
Data on the quantitative and calculated radionuclide composition of BN-350 spent nuclear fuel (SNF) have been obtained. The percentage content of uranium and plutonium isotopes in the SNF, as well as the calculated composition and activity of the main fission products, actinides, and activation nuclides, have been determined. Computational models of fuel configurations were developed using software tools for neutronic calculations. The cask model created for the MCNP program closely replicates the actual construction, including fuel characteristics, geometric dimensions, and radiation shielding materials. The calculations provided data on neutron and photon dose fields generated by a single SNF cask under various scenarios of fuel assembly cladding breach and fuel dispersal, as well as the neutron multiplication factor for different SNF cask configurations (Technical Note “Research on BN-350 Fuel Characteristics,” No. 13-240-03/73 dated 25.09.2025).
Based on the fissile material content in BN-350 SNF, an assessment of the energy potential was conducted (Technical Note “Assessment of the Energy Potential of BN-350 Spent Fuel,” No. 24-405-03/1584vn dated 01.10.2025). The work included determining the cost structure for nuclear fuel production, global raw material prices, and expenses associated with the fuel production cycle. A methodology for assessing the energy potential of BN-350 SNF reprocessing products was developed. For the cost estimation of the energy potential of SNF reprocessing products, the software tool Fuel Quantity & Cost Calculation by The Ux Consulting Company was used. Two scenarios for evaluating the energy potential of BN-350 SNF were considered depending on the reprocessing approach. Scenario 1: Reprocessing of BN-350 SNF without separating fuel assemblies by enrichment. Scenario 2: Reprocessing of BN-350 SNF with the separation of SFA into groups according to initial uranium-235 enrichment.