Sodium experiments related to local blockages in fast reactor subassemblies

Technical Report · Fri Feb 01 04:00:00 EDT 1974

OSTI ID:4940019

Schleisiek, K

Local coolant disturbances in fuel elements of sodium cooled fast reactors are of major importance to reactor safety. Since the experimental investigation of such disturbances in full scale bundles of high performance electrical heaters will be possible only in a few years time, preliminary experiments were performed in a simpler test assembly. It consists of an induction heated tube with a concentric displacer whose profile generates parallel subchannels interconnected so as to form an annulus. The dimensions of the sub-channels largely correspond to those of the fuel element. Part of the cross section is closed by a plate to simulate local cooling channel blockages. This reduces cooling to such an extent as to generate major local increases in temperature and boiling of the coolant. The temperature distributions measured behind the blockage are subjected to a detailed analysis. A semiempirical convection model is developed which approximately describes the relationship between the increase in temperature, the residence time of the coolant in the recirculation zone behind the blockage, and the size of the blockage. The comparison of the measurements performed with water and sodium under the same conditions prove that with blockages of the size investigated the enengy transport is controlled more by convection than by any other transport mechanism. Accordingly the temperature distributions measured can simply be converted to sodium. Application of the model to SNR fuel elements shows that the increase in temperature generated by major blockages (>40%) is probably lower than has so far been assumed. The experiments were compared with results predicted by the local boiling model developed by K. Gast. 49 references. (auth)

• Research Organization: Kernforschungszentrum Karlsruhe (F.R. Germany). Inst. fuer Reaktorentwicklung
• Sponsoring Organization: Sponsor not identified
• NSA Number: NSA-29-031234
• OSTI ID: 4940019
• Report Number(s): KFK--1914
• Country of Publication: Germany
• Language: German

Related Subjects

COMPARATIVE EVALUATIONS
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Breeding
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REACTOR CORES
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