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Topical Issues Concerning Accident Analysis: Methodologies and Management (PAKS Units 1, 2, 3 and 4)

Topical Issues Concerning Accident Analysis: Methodologies and Management (PAKS Units 1, 2, 3 and 4)


Beneficiary Organization Details
Hungarian Atomic Energy Commission
Project Aims
The intent of the project was to co-operate with and to assist the Hungarian Nuclear Regulatory Authority and its Technical Support Organisation in the licensing assessments of the improvement programme of the Paks NPP Units 1 to 4, and in particular in the following fields:

  • Development of accident management procedures;
  • Development and validation of 3D coupled codes;
  • Evaluation of ATWS analysis methods;
  • Development of methodologies for the application of best estimate computer codes for licensing purposes.

Project Results
According to the fields which have been postulated the following tasks were executed:

  • Task 1 – Identification of major accident families characterising beyond-design basis and severe accident scenarios on the basis of available documentation on VVER-440/213 accident analysis and PSA results.
  • Task 2 – Classification of main failure modes and related physical phenomena supposed to take place in the course of such scenarios.
  • Task 3 – Establishing of a set of documented results for beyond-design basis accidents (BDBA). On the basis of these results, establishment of preventive accident management approaches and suggestion of hardware improvement aiming at the definition of recovery guidelines.
  • Task 4 – Overview of applied approaches in linking dynamic codes to large system codes.
  • Task 5 – Execution of selected comparison calculations (appropriate cases and initial and boundary conditions to be specified mutually) using European codes:ATHLET, CATHARE and RELAP. Hexagonal 3D-core dynamic codes: DYN3D, BIPR8 and KIK03D. The events analysed: boron dilution, steam line break.
  • Task 6 – Establishment of methods of ATWS analyses for VVER reactors (initiating events, conservatism to be applied, systems availability, etc.).
  • Task 7 – Definition and execution of an integral type ATWS test for the PMK facility with the aim to produce VVER-specific data base for Task 8.
  • Task 8 – Comparison of capabilities of European codes (ATHLET, CATHARE, RELAP, SMATRA) using test data from Task 7.
  • Task 9 – Comparison of methodologies existing in EU countries.
  • Task 10 – Elaboration of a methodology applicable to VVER type reactors, including: discussion of applied codes and models, status of code validation: assessment of code results for VVER-440/213 specific tests and basic experiments, discussion of the reasons for the selection of the cases, initial and boundary conditions and uncertainties in the plant data, questions of quality assurance as well as accuracy and reliability of quantitative results.
  • Task 11 – Application of the above methodology to each group of transients in the SAR.
  • Task 12 – Familiarisation on the Contractor with the actual status and application of Hungarian licensing practices, laws, rules, standards, special conditions, in order to achieve a mutual understanding of the licensing documents. Proposal for improvements in the documents and procedures.

The project was completed according to the specified Terms of Reference. The start and end dates of the project as specified above are indicative only.
Further Project Results
Further information on the project results could be sought from the beneficiary organizations.

General Information

Topical Issues Concerning Accident Analysis: Methodologies and Management (PAKS Units 1, 2, 3 and 4)
Budget year: 
Types of activities: 
Technical Support Organisations
Installation types: 
VVER 440-213
Duration (months): 
Old reference: 
Effective contract date: 
Closure date: