Beneficiary Organisation Details

Paks NPP
http://www.npp.hu

Project Aims

The main objectives of PH2.02/94 project were threefold:

• To assess the integrity of PAKS NPP SG collectors by performing fracture mechanics and leak rate calculations for postulated through wall cracks to demonstrate that:
  -no likely cracks will reach critical size during the plant's anticipated life time;
  -any hypothetical through-wall crack will leak at a sufficient rate to ensure its detection before it can grow to critical size. Aim was to show that no rapid acceleration to full break would occur after detection and to specify the requirements for non destructive test (NDT) examinations and Leak Detection System (LDS) capacities, which would allow to apply Leak Before Break (LBB) concept for PAKS NPP SGs;
• To review the design and operational experience gained with the Leak Detection System LEMON 1.0, installed at unit 2 of PAKS NPP and develop a proposal for design improvements based on the results from the SG collector integrity assessment;
• To review the existing Design Basis Accidents (DBA) and perform additional analyses in order to develop a proposal for a plant strategy to prevent, detect and mitigate potential PRISE events.

Project Results

• A comprehensive evaluation of the major safety issues related to PRISE events was performed and detailed results were summarizes for each particular safety issues and a proposal was developed for an improved strategy to prevent, detect and mitigate such events at Paks NPP.
• The insights from the project results were futher analysed to develop proposals for plant design modifications, including proposals for modification of plant operational and emergency procedures for handling of PRISE events.
• The proposed measures were grouped in three fields: prevention, detection and mitigation as per the proposed defence-in-depth strategy.
• The proposed modifications were presented separately for design basis accidents and beyond design basis accidents.

Further Project Results

a) See the attached file
b) Further information on the project results could be sought from the beneficiary organisation.