Fast Reactors and Accelerator Driven Systems Knowledge Base

Conference Article: Analysis of the core seismic experiments using the cosmos/M code

Abstract

In a typical Liquid Metal Fast Breeder Reactor (LMFBR) the fuel pins are contained in hexagonal assemblies which rest on the diagrid. In a cluster of assemblies, there is a possibility of contact between the neighbouring assemblies at the pad level during a seismic event. The deflected core may have more reactivity due to core compaction. Therefore, core seismic analysis is an important item to ensure fast reactor safety in an earthquake. Numerous experiments have been conducted in different countries on single assembly, a row of assemblies and on small and large clusters. In order to enhance the quality and extent of validation of the codes it was of interest to analyse the data using different codes. Under the Co-ordinated Research Program on ‘Inter comparison of LMFBR Seismic Analysis Codes’ analyses have been performed for the following tests. Italy - Shake table testing of 7 and 19 element clusters. Japan - Natural frequency and impact tests on single assembly in air and water Japan - Shake table testing of 29 element row and 37 element cluster France - __ do __ Rapsodie core mock-up. The calculated results were compared with experimental data in respect of - maximum and RMS displacement and acceleration of a particular assembly - Fourier Spectra of displacement and acceleration. It was found that the displacement responses; matched very well but there was a discrepancy in the acceleration. The possible causes of this are i) imprecise determination of shock parameters ii) Filtering of high frequency acceleration signal in experimental measurements. Due to the limitations of the computer program, the large cluster problem (Rapsodie mock-up) could not be solved. Apart from this, no other major limitation of the code was identified. It was concluded that the code has been validated against experimental data. Apart from this, the participants have also derived immense benefit in the areas of modeling of gaps, damping, fluid effects, measurements and processing of data.

view the full text of this article (70 pages, format: PDF, size= 2782kB)

Reference:

Final research co-ordination meeting on intercomparison of liquid metal fast reactor seismic analysis codes. Bologna (Italy). 30 May - 2 Jun 1995

International Atomic Energy Agency, Vienna (Austria)

IAEA-TECDOC--882, pp:221-290