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Safety and Reliability of NPP

Guaranteeing the safety and reliability of NPPs requires a comprehensive assessment of whether the plant is operated in accordance with the actual project, with the applicable national safety requirements and with the relevant limits and conditions. The range of support activities offered by UJV Rez covers both legislative and operational aspects.

From a legislative point of view, the principal activities include nuclear safety demonstrations for nuclear power plant commissioning and lifetime extension, or other legally required safety demonstrations such as facility reconstructions, changes in operating conditions, or other changes that may affect nuclear safety.

From the operational point of view, we perform a series of support activities to monitor and control operational parameters, and evaluate deviations from nominal parameters, including streamline operational, control, and maintenance activities, etc. Based on the results of these support activities, we design the necessary measures to increase operational reliability and safety.

Safety assessment is implemented by:

  • Continuous monitoring of nuclear and technical safety (supervision, inspection, testing)
  • Deterministic assessment of nuclear safety (safety assessment reports)
  • Probabilistic assessment of nuclear safety (the so-called "living probability safety assessment" - Living PSA and its applications – e.g.: Safety Monitor)
  • All the abovementioned activities include the latest research and development findings
Computing station
Reactor Control Panel
Simulation of the mapping of the evacuation of schools during a severe accident
Map view and evaluation of radiative situation monitoring
Mathematical model of pressure vessel
Model of experimental facility THAI+ operated by Becker-Technologies GmbH.
Model of experimental facility THAI+ operated by Becker-Technologies GmbH.

Our Services

  • Safety analyses for the purpose of the licensing process, including independent verification analyses and documentation;
  • Preparation and updating of safety reports and license documentation;
  • Preparation of methodological procedures for analysis and for the own licensing process;
  • Conceptual studies on nuclear safety;
  • Analyses and preparation of supporting documents for the fuel cycle;
  • Analyses of severe accidents and strategies for severe accident management;
  • Analyses of thermomechanical behavior of nuclear fuel in operational and emergency conditions;
  • Best-estimate analysis of nuclear fuel coating damage and evaluation of fission product release into the coolant;
  • Analyses and preparation of backgrounds for calculation of radiological consequences of accidents;
  • Analyses and preparation of backgrounds for PSA studies;
  • Thermohydraulic analysis for PTS needs;
  • Experiment evaluation.
Reactor physics and fuel cycle support
Safety analyses


Severe accidents and thermomechanics
  • Comprehensive analyses of the operation of nuclear power plants,
  • Suggestions for measures to improve safety of the operation,
  • Development and implementation of PSA applications for risk-oriented decision making:
    • Immediate operational risk monitors for NPPs,
      Online maintenance,
      LaP optimization and test intervals,
      Prioritization of safety measures,
      Cost benefit analysis.
  • Development of Probability Safety Assessment Methods (PSA).
Reliability and risks
  • Analyses to support the development of emergency operating procedures and severe accident management guidelines (EOPs and SAMGs),
  • Validation of emergency procedures,
  • Implementation of new best estimate methods,
  • Support for margin management on NPPs,
  • Proposals for measures to improve the ergonomics of emergency procedures,
  • Evaluation of training on simulators, proposals for modification of procedures,
  • Training in the area of safety analyses including development of input decks,
  • Training in the severe accident phenomenology of  and SAM,
  • PSA training,
  • Development and implementation of supporting tools to support the training of operators, TCS and emergency center staff.
Reliability and risks
Safety analyses


Severe accidents and thermomechanics
  • Reliability, serviceability, and maintainability analyses of:
    • Complex technological systems in energy, transport, production,
    • Protection and control systems including digital deterministic (FMEA, FMECA) methods and probability assessment (eg fault-tree method);
  • Environmental Impact Assessment, Human Factor and Common Cause Failures in Reliability Analyses;
  • Support of Reliable Designing, Application of the Diversity Principle;
  • Proposals for measures to increase reliability (project and organizational);
  • Analysis of operational experience (adverse events), identification of potential outages;
  • Analyses of equipment performance in severe accidents;
  • Monitoring and development of methodologies for assessing the life and reliability of safety-critical PO and SO measuring chains;
  • Analyses of production reliability, efficiency evaluation, and maintenance quality;
  • Reliable maintenance programs;
  • Analyses of human factor reliability;
  • Collection and evaluation of device reliability data;
  • Calculation of reliability parameters of components and systems, reliability prediction.
Reliability and risks
  • Development of new analytical procedures;
  • Verification and validation of computational programs and models;
  • Experiment evaluation.
Safety analyses


Severe accidents and thermomechanics
  • Methodological support in the field of safety,
  • Assessment of safety documentation and independent verification analyses,
  • Supporting the commissioning of new nuclear resources,
  • Transfer of the latest R&D observations for applications in decision-making procedures
Director of division
  • Criticality analyses, shielding (pools, fresh and spent fuel containers);
  • Risk-based categorization of equipment for inspection and maintenance purposes;
  • Development of tools and methodologies for diagnosting of regimes and and components of nuclear power plants;
  • Development of complex systems for advanced processing of operational data, including their secure connection to existing NPP operating systems;
  • Implementation of advanced information, communication and mobile technologies to increase operational safety and reliability;
  • Training courses and internships in the field of the safety assessment of NPP operation.
Director of division


Division of Nuclear Safety and Reliability

  • Address:  ÚJV Řež, a. s., Hlavní 130, Řež, 250 68 Husinec, Czech Republic
  • Phone: +420 266 173 558     
  • Fax: +420 220 941 029
  • E-mail: