[en] In french nuclear PWR power plants, water steam high energy pipes run along the electrical and reactor buildings. In order to protect these safety buildings we have chosen to restrict the displacements of the pipes in case of breaking by the settlement of anti-whip structures. To design these structures and to better evaluate the impact force pipe and R.C. structures, experiments on straight sections pipe crushing have been carried out. These static and dynamic tests have allowed us to evaluate the impact force and to perform the design of anti-whip structures by considering the energy absorbing properties of the pipe itself. (orig.)

[en] EDF has initiated a research program on the non linear behaviour of RC slabs subjected to short time loads, such as soft missiles. This program includes an experimental part and a theoretical analysis to simulate, through computation models, the behaviour of tested plates and try to deduce some pratical rules for plastic design. The ultimate purpose is to show that it is possible to drastically reduce the bending reinforcement of anti-missile slabs without fearing failure or even large deflection. We present in this paper the first test results regarding accidental loads due to small aircrafts (LEAR JET or CESSNA). (orig./HP)

[en] The method described is used to test failure mechanisms and to calculate the corresponding ultimate loads. The main advantages it offers are simple modelling, the possibility of representing all the prestressing and reinforcement steels simply and correctly, and fewer degrees of freedom, hence lower cost (the program can be run on a microcomputer). However, the model is sensitive to the arrangement of the interface elements, presupposing a given failure mechanism. This normally means testing several different models with different kinematically possible failure patterns. But the ease of modelling and low costs are ideal for this type of approach. (orig./RW)

[en] Studies on the behaviour of reactor containments under off-design conditions have been conducted in France on both 900 MW PWR with metallined containments and 1300 MW PWR with dual concrete wall containments. The results show that: 900 MW PWR containments should keep their intergrity until failure since the risks of metal liner tearing are low; the behaviour of 1300 MW PWR containments is governed by the transverse carcking of the concrete which, due to the resulting leakage rate, tends to control internal pressure to a value less than collapse pressure and mechanical penetrations exhibit a mechanical strength which is well above containment collapse pressure. (orig./HP)

No abstract available

[en] The aims of this study are to obtain experimental data and theoretical evaluation of the transient field pressure existing on importants buildings of the plant. The knowledge of the pressure loading permits then to predict the structure mechanical behaviour. For this purpose the cylindrical reactor building and the parallelepipedic fuel building have been modelized to a 1/40 scale. These models were realized as carefully as possible with prestressing in the thickness of microconcrete walls and were submitted to incident shock waves obtained by T.N.T. explosions. Several characteristics explosion directions have been tested. Experimental data were recorded with pressure and displacement transducers and also by accelerometers. The results show that: 1) the geometrical dihedral between reactor and fuel building induces local overpressures five times the incident pressures; 2) no apparent damage occurred on the structure, for the range of field pressure tested so far; this may related to only small effects of resonances. Simultaneously a tridimensional, acoustic code has been developed an conveniently correlates experimental data. (orig./HP)

[en] This paper presents the results of the nonlinear axisymetric analysis of the behaviour of containment buildings (PWR 900 MWe with metallic skin and PWR 1300 MWe without any skin), under LOCA pressure and temperature loadings. The evolutions of pressure and temperature from the accident are the following: increase of pressure 0.3 bar/hour and increase of temperature 2⁰C/hour. This thermomechanical study has been made with the Finite Element Method, and the CEASEMT system code has been used. The objectives of this study have been obtained: - the pressure of the first of concrete - the pressure of trough fracture of concrete - the ruin modes of the containment building However, the spatial discretization of the structure used in this Finite Element analysis induces limitations to the quantitative evaluation of the fracture of concrete, because the informations about fractures are known only on discrete points. From this analysis, we are not able to show up phenomeneon like strain localizations. (orig./HP)

[en] Since 1974 CEA and EDF have developed in France a large programme with the aim to work out a means of computation reliable enough for the knowledge of the behaviour of reinforced concrete walls under missile impacts. The shots were performed on reinforced concrete slabs, the thickness of which were chosen to represent in a realistic way the thickness of the wall of a reactor containment. The scales used in this modeling were mainly one-half and one-third. The following parameters were kept constant: the properties of the concrete and the geometric shape of the missile (flat nose). Also studied were the effects of variation of parameters like missile velocity (25-450 m/s), its mass (20-300 kg), ratio of the missile diameter to the thickness of the slab (0.24-2.9) and characteristics of the steel reinforcement. The results of these tests may be summarized in a homogeneous perforation formula in the case of a velocity lower than 200 m/sec: Vsub(c)²=1.7 sigmarhosup(1/3)(sigmae²/M)sup(4/3), where Vsub(c), is the minimum velocity for perforation, phi diameter of the missile, M its mass, sigma the ultimate compressive strength of the concrete, rho its density and e its thickness. (Auth.)

No abstract available

[en] Since 1974 C.E.A. and E.D.F. developed in France a large programme with the aim to work out a means of computation reliable enough for the knowledge of the behavior of reinforced concrete walls under missile impacts. In this paper are described the subsequent tests and the interpretation of the whole programme. The shots were performed on reinforced concrete slabs, thickness of which were chosen to represent in a realistic way the thickness of the wall of a reactor containment. The scales used in this modeling were mainly one half and one third. In any case the similarity law used in this work is such to keep the value of velocity unchanged. In a first step the following parameters were kept constant: thickness and properties of the concrete, reinforcement ratio, geometric shape of the missile. On the other hand were studied the effects of variation of parameters like the missile velocity (90 to 200 m/s), the missile diameter (0.2 to 0.3 m) and its mass (20 to 300 kg). Taking into account this first series of tests formulae for computation of a limit perforation velocity, Vsub(e) and of a minimum protection depth, e, were worked out as functions of the characteristics parameters of projectile and wall. In a second step there was tried to define the limits of validity of these formulae in the case of variation of the following parameters: ratio of the missile diameter to the thickness of the slab (0,24 to 2,9), velocity of the missile (25 m/s to 450 m/s), characteristics of the concrete, characteristics of the steel reinforcement, shape of the projectile