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Enhancement of safety assessment capabilities of Bulgarian Nuclear Safety Authority

Enhancement of safety assessment capabilities of Bulgarian Nuclear Safety Authority


Beneficiary Ornganisation Details

Bulgarian Nuclear Regulatory Agency:

Project Aims

The project main aim was to provide EU expertise to:

  • Support the Bulgarian Nuclear Regulatory Agency (NRA) and its TSOs (Risk Engineering Ltd.) in the various assessments of upgrading measures proposed for Units 3 to 6 of Kozloduy NPP (covering design and operational aspects) for licensing purpose, and
  • Transfer of know-how to NRA and its TSOs and in long term perspective, enhancing their competence and capabilities.

NRA and its TSOs under the Contractor’s guidance had actively participated in project related tasks, in order to receive an efficient on-the-job training.

Project Results

The following issues related to NPP Kozloduy safety improvement programmes, have been reviewed and assessed under the current PHARE project:

  • Justification of reactor core internals strength according to new standards;
  • System for gas removal from the reactor;
  • Evaluation of the probability of reactor pressure vessel failure;
  • Additional substantiation of SG strength;
  • Primary circuit Dn 200 and Dn 500 pipelines reliability increase;
  • Modernisation of Emergency Protection Control System;
  • Analysis of internal flood consequences;
  • Safety/ seismic/ quality classification of unit 5 and 6 systems and components;
  • Qualification of computer codes for accident analysis;
  • PTS analysis;
  • A complete list of analysis of design and beyond design basis accidents;
  • Analysis of emergency feed water system (TX) and peculiarities of SG feed water system process conditions;
  • Study of processes which may lead to unmanaged accident in the event of failures of control safety systems;
  • Risk analysis of the possibility of suction line break of the safety injection pumps TQ2;
  • Installation of flow reducers limiting the flow rate in case of loss of SG header tightness at the primary side;
  • Static-dynamic strength analysis of primary circuit;
  • Installation of more than one system for leak detection;
  • Enhancement of the reliability of SG safety valves of units 5 - 6;
  • Heating water for high and medium pressure safety injection above 55˚ C;
  • Implementation of system for primary leak detection;
  • Installation of system for hydrogen detection and burning at units 5 and 6;
  • Installation of equipment for measuring activity of the gases released through the vent stack;
  • Replacement of the “Hindukush” (CM-2M) system at units 5 and 6 with a more efficient one;
  • Limiting the effects of secondary water or steam pipe breaks in reactor building;
  • Installation of an automated system for cold overpressure protection;
  • Improvement of the reliability of diesel generators/ DG protection;
  • Installation of additional diesel generator per each unit for unit consumers;
  • Develop and implementation of a radiation monitoring system for severe accidents.

The budget for this project was 1400 000 euro.

Further Project Results:

Further information on the project results could be sought from the beneficiary organisation.

General Information

Enhancement of safety assessment capabilities of Bulgarian Nuclear Safety Authority
Budget year: 
Types of activities: 
Regulatory Authorities
Installation types: 
VVER-440/230 + 1000
Duration (months): 
Old reference: 
Effective contract date: 
Closure date: