Ageing and air leakage assessment of a nuclear reactor containment mock-up: VERCORS 2nd benchmark

Julien Niepceron (1) , Laurent Charpin (2) , Manuel Corbin (1) , Benoit Masson (1) , Jean-Philippe Mathieu (2) , Jessica Haelewyn (2) , François Hamon (2) , Magnus Ahs (3) , Sofia Aparicio (4) , Mehdi Asali (5) , Bruno Capra (6) , Miguel Azenha (7) , David Bouhjiti (8) , Kim Calonius (9) , Meng Chu (10) , Nico Herrman (11) , Sergio Jimenez (12) , Jacky Mazars (13) , Georges Nahas (14) , Jan Stepan , Thibaud Thenint (15) , Jean-Michel Torrenti (16)

1 EDF DT - EDF Direction Technique
2 EDF R&D - EDF R&D
3 Skane University Hospital [Lund]
4 ITEFI - Instituto de Tecnologías Físicas y de la Información (ITEFI)
5 Oxand S.A.
6 OXAND S.A.
7 ISISE
8 3SR - Laboratoire sols, solides, structures - risques [Grenoble]
9 VTT - VTT Technical Research Centre of Finland
10 SNERDI
11 KIT - Karlsruher Institut für Technologie
12 CIMNE - Centre Internacional de Mètodes Numèrics en Enginyeria
13 Grenoble INP - Institut polytechnique de Grenoble - Grenoble Institute of Technology
14 IRSN/PSN-EXP/SES/LMAPS - Laboratoire de Modélisation et d’Analyse de la Performance des Structures
15 SIXENSE NECS
16 Université Gustave Eiffel

Electricité de France (EDF) operates a large fleet of nuclear reactors and is responsible for demonstrating the safety of facilities, including concrete containment buildings (CCB), which are non-replaceable components. The leak-tightness of CCBs is assessed every 10 years during integrated leak-rate tests (IRLT). For double-wall containments, which have no metallic liners, the leak-tightness is strongly influenced by the degree of cracking of concrete and opening of the cracks, which mostly depends on (a) the prestress decrease due to the delayed strains of concrete, and (b) the saturation degree of the concrete wall. Therefore, to optimize the maintenance programs on CCBs, it is important to predict the evolution of drying, creep shrinkage strains of concrete to be able to correctly assess the pre-stress losses, and finally the air leak-tightness at a structural level during pressure tests or under accidental loadings. To improve our understanding and identify the best modelling practices on this issue, a large experimental program called VERCORS was launched in 2014. VERCORS is a 1/3 mock-up of a 1300 MWe nuclear reactor CCB. It is widely instrumented, and its concrete thoroughly studied. A specific attention has been paid to ensure it is consistent with real CBBs features in EDF’s nuclear fleet. To complement its internal R&D efforts, EDF decided to associate external partners to this program. One of the means for this is the organization of benchmarks, where all teams are given data and information about the mock-up and are asked to forecast its behaviour. The present paper reports the organization and findings of the 2nd benchmark which was organized in 2018 and gathered several international teams around the same objective: improve the confidence in the modelling of structural behaviour as well as the leak-tightness of concrete in containment walls under pressure test loading.

Mots clés: Containment; Concrete; Benchmark; Creep; Shrinkage; Leak-tightness

Domaines: Génie civil nucléaire

Julien Niepceron, Laurent Charpin, Manuel Corbin, Benoit Masson, Jean-Philippe Mathieu, et al.. Ageing and air leakage assessment of a nuclear reactor containment mock-up: VERCORS 2nd benchmark. Nuclear Engineering and Design, 2021, 377, pp.111136. ⟨10.1016/j.nucengdes.2021.111136⟩. ⟨hal-03711943⟩