The overall project objectives follow the general project idea: to develop the validated non-destructive tool to monitor

the swelling and thermal ageing degradation mechanism from the LTO point of view.

The main project goals are:

• To develop the tool for the assessment of the prolongation of the lifetime of the LWR NPPs – the main

project goal is to assess and propose the industrial implementation of the selected NDT techniques to the nuclear power plants. This specific nuclear environment poses a threat to electronic monitoring systems  in general. The long-term operation experience of the consortium members with the industrial application  of the NDT techniques endures the achievement of the results. Nevertheless, the LTO-specific degradation  mechanisms (swelling and thermal ageing) and their detection on time require a massive set of experimental validation via destructive (or conventional) techniques and simulation s leading to the correct and reliable interpretation. This requirement will be fulfilled by the DELISA-LTO project. The achievement of the goal will be verified by the report, summarizing the obtained results with the direct proposal of the implementation of the measurement system to the nuclear reactor.

• Propose the methodology of the qualification of materials/components for the design life extension –

the methodology itself is a very important milestone to future implementation. The methodology will be based on the experiments and conclusions coming from the project activities and its usability will be validated with the representatives of the industry at the Technology Transfer Board (TTB) meetings. The achievement of the goal will be verified by the issue of the methodology summarizing the implementation aspects.

• Provide the international benchmark on swelling modelling – the modelling of the swelling phenomena is currently provided by few validated tools at the national level (i.e. European procedure VERLIFE (11), Ukrainian ПМ-Т.0.03.333-15, (12)), this project goal was specifically selected to harmonize the procedures and explicitly assess the relevancy in between the used tool and to assess the applicability to the VVER units with link to other LWR technologies. Comparison of rules-making and practices concerning swelling evaluation and calculation of RPV internals for PWR type reactors including benchmark calculation and developing recommendations for improvement of approach to swelling evaluation will be performed. The implementation of this task builds upon the previous initiatives and provides the accomplishment of this task to contribute to the international methodologies at the highest level. The achievement of the goal will be verified by the report, summarizing the obtained results with the assessment of the benchmark execution and outputs relevant to the specific methodologies and set of recommendations.

• Provide the set of recommendations for the future LTO related assessments in general based on the main project outputs – specifically for the detection of the swelling and thermal ageing by the NDT.

The achievement of the goal will be verified by the report, summarizing the obtained results with the direct proposal of the implementation of the measurement system to the nuclear reactor. This document will identify the potential obstacles and relevancy in between the specific assessments systems and specific features of the nuclear industry.

• To harmonize the national methodologies and techniques in order to obtain the generally acceptable set of recommendations for the assessment of the swelling and thermal ageing from the (not only) LTO point of view – One of the most important aspects of the DELISA-LTO proposal and consortium is the presence of the representatives of the national entities with very long experience in the operation of the VVER type of units. This deep knowledge will create very unique synergies to gain a very high level of relevance of the project outputs harmonizing the ongoing work (esp. in the development of the new techniques). The harmonizing work will be performed specifically for the NDT validation and swelling benchmark. The achievement of the goal will be verified by the report, summarizing the obtained results and identified the relevance of the produced data – with respect to the national legislation and guidelines.

To illustrate the wide impact of the proposal, it was divided into 3 main categories – social, economic and scientific impacts

Societal impacts

The project results will be applied for safer are the more effective long-term operation of NPPs, which besides the economic effect maintains workplaces that would be lost in the case of premature closure of plants. A laboratory that will host the databank of extracted samples and process all data from the project will itself create several workplaces and provide work to several young professionals. The proper dissemination of information on the project results can be reflected by a more positive attitude of the public towards the operation of NPPS as well as towards radioactive waste management and environmental concerns.

Economic impacts

To assure safe NPP operation and minimization of unplanned outages caused by a failure of the equipment, it is necessary to manage the ageing of individual CCS at NPP which are important for the reliable, safe and effective operation of the plant and for minimization of unplanned outages.

Monitoring of ageing and remaining life evaluation provides information on the status of those technical parameters which are important for safe operation during the lifetime and during the extended lifetime of the plant and prognosis of their reliable functioning. Material data from the project will serve for the improvement of lifetime management of operating units and optimization of LTO programs, including identification of the available margins in the operation of NPP equipment, which are items with a positive economic impact on the operation of NPPs. Information collected within the DELISA-LTO project enables more efficient operation of NPP equipment what transforms into improved operation indicators such as load factor and availability factor, with a direct impact on economical results of NPPs. Moreover, a better understanding of the status and radiation conditions of materials from decommissioned units allows their better categorization and optimization of conditioning and processing for their disposal, which can also reduce the cost of disposal.

Environmental impacts

Nuclear power technologies are low carbon technologies and the replacement of fossil energy sources with nuclear reduces CO2 emissions. Replacement of fossil (coal, gas) energy sources with nuclear ones can be evaluated by about 2500 kg of CO2 for every produced MWh of electricity. Extended operation of the existing nuclear units will maintain a higher ratio of low-carbon energy sources in Europe’s energy mix. The proposed project is one of the measures that support the operation of NPPs beyond their design lifetimes and hence contributes to the production of clean energy. The project results can be used for a better understanding of radioactive waste composition which can lead to the reduction of the amount that had to be disposed of.

Scientific impacts

In the scientific field, the proposed project will provide information necessary for the development of new, more exact models and tools for predicting material behaviour on NPP operation. The databank of collected material samples and their properties will serve as a unique source of information for any future material problems involving VVER units beyond the national borders, and also for academic research and education of university students in the nuclear field.

• Thermal Ageing and Swelling: Investigate the impact of thermal ageing and swelling on key reactor components, such as steam generator tubes and internals.
• Non-Destructive Testing (NDT): Implement and validate NDT monitoring methods for evaluating system integrity during LTO.
• Modelling and Simulation: Develop simulation tools to forecast material degradation and identify failure risks.
• Experimental Validation: Collect and analyse experimental data to verify models and methodologies.
• Safety Margin Evaluation and Integrity Assessment: Assessment of component condition and development of methodologies for identifying unacceptable material states.
• Guideline Development and Standardisation: Consolidate best practices into guidelines for material testing under LTO-relevant conditions, interpret NDT signals in aged materials, and harmonise assessment procedures that can be used across European nuclear operators.

CVŘ, ÚJV, VUJE, STUBA, VTT, BZN, EK-CER, IPP, SSTC NRS

1.6.2022 – 31.5.2026

Budget: 3 276 263.00 EUR

Technical Project Leader:

Ondřej Srba

Dissemination and Communication Leader:

Vladimír Slugeň

Jana Šimeg Veterníková

This project has received funding from the HORIZON-EURATOM-2021-NRT-01-01.