Method for estimating the blast-resistance and carrying capacity of a fast-reactor vessel during an unspecified accident

Abstract

The main vessel of a BN-600 fast reactor is fabricated from chrome-nickel steel in the form of a thin-walled tank with a cylindrical shell, elliptic (BN-600) or spherical (BN-800) bottom, and a conical cover. The shell is connected to the bottom through a support ring, on which rests a rigid support collar, on which, in turn, the reactor equipment is mounted. The neck of the cover supports a large rotating plug. The reactor is filled with liquid sodium, and the cavity above it is filled with argon.Experimental and theoretical-computational investigations [1] have shown that the static strength of the vessel is sufficient for reliable and safe operation. However, the question of the strength during an accident under dynamical loading as a result of, for example, sudden explosive release of energy in the fuel core, remains open. Thus it is important to study the dynamic strength of the vessel. In this connection, we propose a method, which we have developed, that makes it possible to assess, on the basis of data from model explosive tests, the blast-resistance and, on the basis of these tests, the carrying capacity of the vessel in an unspecified accident.The experiment was conducted on two BN-800 models with a scale of 1:10, in one of which (model I) the intrareactor outfitting* was not modeled. The model vessels (inner radius of 643 mm; thickness of 3 mm) were welded, just as the prototype, using 12Khl8N10T steel (Fig. 1). The construction of the model, together with the simulation of the intrareactor outfitting (model II), is simplified (without increasing the carrying capacity of the vessel) as follows:the fuel core and the breeding zone, the intratank shielding, displacers, displacement pumps, elevator compartments, the pressure pipelines, the gas blow-through system, the collectors, and the accident containment vessel, are excluded; the vessel is welded using the smallest number of sheet panels; the simulators of the intrareactor outfitting are fabricated from carbon steel; the bellows are replaced by thin (0.5 mm) shells; a massive shell case, welded to the neck in order to simulate the hydraulic seal, is used for the large rotating plug; the small rotating plug and the rotating column were replaced by a single stepped hollow-core plug, bolted in the shell case; the inner radiation shielding consists of two coaxial 4 mm thick shells, welded to the supporting collar.The construction of the model-I vessel was virtually identical, but the neck was covered with a plate on bolts, the protuberances of the heat exchangers on the cover were replaced by capped pipe stubs, and the supporting collar was replaced by a massive disk with radial stiffening ribs.A diagram of the experimental arrangement is displayed in Fig. 1. The models, placed on the supports (similar to a reactor), were filled with water, the cavity above which remained filled with air at atmospheric pressure. In this manner we simulated the presence of liquid sodium and the gas cushion above it in the reactor. The high temperatures (-400-600~ and the...

Dynamic responses of discrete multi-layered explosion containment vessels with the consideration of strain-hardening and strain-rate effects

“…(8) and (9), respectively. The impulse loading is considered as an equivalent initial velocity V 0 determined by Eq.…”

“…Furthermore, Refs. [4][5][6][7][8] deduced a relationship with the planestrain ring theory between the explosion weight and the maximum plastic deformation. For air-filled ECVs, by using the plane-strain ring theory, Duffey [9,10] obtained the final radial displacement in the explosion section and the displacement along the axial direction, which were both in good agreement with experimental results.…”