Pipe whip analysis for nuclear reactor applications

Abstract

The main problems encountered in pipe whip analysis are discussed and the way the authors tried to solve them is described. Such problems are: 1. (a) Breakage locations: AEC criteria are presented and discussed. 2. (b) Force computations: The jet force intensities during the accident are computed following Moody's theory. A computer program makes such an analysis automatically. Forces consequent to a longitudinal and a circumferential break are calculated; The forces consequent to the longitudinal break are computed as a sum of the forces consequent to two circumferential breaks, a mitigation coefficient is assumed. 3. (c) Preliminary analysis: Provided that a ‘restraint solution’ is necessary (and the related criteria are briefly discussed), a tentative distribution of the restraints is computed by means of a simple energy balance between the work done by the jet forces and the work absorbed both in the pipe and the restraint. A computer program makes such an analysis automatically. 4. (d) Final solution appraisal: The tentative solution obtained in the initial step is re-evaluated by means of a detailed dynamic elastoplastic code (FRUSTA, which is described in the companion paper). A typical example is given, the jet forces and a tentative restraint distribution are computed; the various models used in the final appraisal solution are described and the results are evaluated mainly in order to check the validity of the preliminary criterion.