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Consequences (study) of Live Steam Pipe Rupture (Including Qualification of MSIV)

Consequences (study) of Live Steam Pipe Rupture (Including Qualification of MSIV)


Beneficiary organisation details
NPP Dukovany, Czech Republic
Co-beneficiaries were NPP Bohunice (Slovak Republic) and NPP Paks (Hungary).
Project Aims
The overall objective of this project was to contribute to increasing safety of operation of VVER-440/213 nuclear power plants trough safety reassessment of the secondary steam piping located in the intermediate building of the VVER-440 NPP.
The specific objective of this project was to:

  • Provide the beneficiary with the results of the analysis of the potential consequences of a steam line rupture occurring in the +14,70 area of the intermediate building of VVER-440 nuclear power plants;
  • Develop proposals for hardware modifications in this area in order to enhance the global safety of the operation of VVER-440/213 plants.

Project Results
The project was oriented to safety reassessment of consequences of rupture of particular part of secondary steam pipelines (occurring in the +14,70 area of the intermediate building), with high potential risk of impact to principal emergency systems of the NPP. The main results of the project were as follows:

  • Detailed review of the most significant existing accident analyses to verify that even in the simultaneous loss of all six steam generators, the consequences on the reactor core and vessel are acceptable;
  • Detailed stress analysis of the steam and feedwater lines outside the hermetic zone aimed in determination of postulated break locations;
  • Dynamic calculations to justify that the implementation of whip restraints was not necessary for some of the postulated rupture points;
  • Review of a new routing of the emergency feedwater pipeline system, proposed by NPP Dukovany, to verify whether the new design is acceptable with regards to the safety criteria used within this project;
  • Calculation to justify that the modifications/upgrade, proposed for existing main steam isolation valves, fulfil their safety function;
  • Assessment of the behaviour of the secondary safety and relief valves during accidents and investigation of possibilities to install a new discharge system;
  • Review of procedures, elaborated for electrical equipment qualification, and comments for their practical implementation;
  • Summary of proposed modifications, list of modified and/or added equipment including price assessment for the procurement and installation.
  • Final document summarizing all safety features of the proposed modification;
  • Report, discussing applicability of the project results at Bohunice and Paks NPPs.

Project objective have been met and the project was completed in time and in accordance with agreed work plan.
Further Project Results
a) See the attached file.
b) Further information on the project results could be sought from the beneficiary organisation.

General Information

Consequences (study) of Live Steam Pipe Rupture (Including Qualification of MSIV)
Budget year: 
Czech Republic
Types of activities: 
Design safety
Installation types: 
VVER 440-213
Duration (months): 
Old reference: 
Effective contract date: 
Closure date: