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Review of accident analysis units 1-4 (Item C)

 
Review of accident analysis units 1-4 (Item C)

Description

Beneficiary Organisation Details

Kozloduy NPP:
http://www.kznpp.org

Project Aims

The objective of the project was to review the accident analysis prepared for the Kozloduy Unit 1-4 establishing setpoints for actuation of the unit Safety Systems. The following accidents had to be considered:

  • steam system piping failure;
  • loss of normal feedwater;
  • feedwater system pipe break;
  • boron dilution;
  • rod ejection;
  • inadvertent opening of a pressurizer relief valve;
  • steam generator tube rupture.

Project Results

  • For each accident, a set of conservative assumptions was established. In particular, the single failure criterion was applied throughout the analyses. The RELAP5/MOD2 computer code was used to analyze most of the thermal and hydraulic transients associated with the accidents under evaluation. A benchmark calculation was performed with the DYNAMIKA code developed by the VVER designer (Gidropress, Moscow). Credit was taken, in the analyses, for the plant modifications included in the Kozloduy NPP Small Reconstruction Programme;
  • It was concluded that providing the equipment assumed in service in the analyses is operating as designed and that the operator is taking the required corrective actions on time, the results of the analyses were indicating that the Kozloduy units 1 and 2 could cope with margin with the accidents analyzed. The proposed modifications in the protection systems considered in the accident analyses represented an improvement of safety for the Kozloduy NPP Units 1 and 2;
  • A few recommendations for hardware modifications and performance of additional analyses were made.

Further Project Results

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


General Information

Title: 
Review of accident analysis units 1-4 (Item C)
Programme: 
PHARE
Budget year: 
1991
Countries: 
Bulgaria
Types of activities: 
Design safety
NPP: 
Kozloduy
Installation types: 
VVER 440-230
Duration (months): 
264
Contractors: 
Westinghouse
Sub-contractors: 
Energoproject, Ltd
Status: 
Completed
Old reference: 
PH/91(C)
Effective contract date: 
01/07/1993
Closure date: 
01/01/1994