R&D Category: -Thermo hydraulic testing
4 documents found
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Hydraulic tests with measuring and control plug for KNK II temperature transient experiments (TETRA) Hydraulische Tests mit Mess- und Regelstopfen fuer KNK II Temperaturtransientenexperimente (TETRA)
Reimann, G.;Grossgarten, H.-D.;Heckert, KKernforschungszentrum Karlsruhe GmbH (Germany)
KFK-PSB--01.01.04P20B - German - 1985
Abstract: For the temperature transient experiments (TETRA) at KNK II the sodium flow rate of a 19-pin test bundle integrated in an annular fuel element shall be reduced and the coolant temperature consequently increased with the help of a measuring and control plug. A valve will act as orificing device. It is designed in such a way that even in closed condition a remaining mass flow will be given, with which the aimed maximum coolant temperature of 750 deg. C will be reached at the outlet of the test bundle. With the nominal mass flow of the test bundle of 1.35 kg/s and a core pressure drop of 1.33 bar, for the test operation with maximum coolant outlet temperature a minimum mass flow of 0.76 kg/s and a test element pressure drop of 0.4 bar is calculated. The experimental plug has therefore to provide a pressure drop of 0.9 bar. During the hydraulic tests the pressure drop of the plug and the characteristic of the valve had to be determined. For this purpose a test line with the same inner dimensions and installations as the plug was established and a first series of experiments was performed in a water circuit. The experiments showed that most of the pressure drop was caused by the valve. It amounts to 0.5 bar with the minimum mass flow, i.e. the aimed pressure drop of 0.9 bar is not yet reached. Further tests will be performed with smaller ring gaps of the valve. In a second series of experiments the characteristics of four valves with different geometries have been determined
Key words: annular fuel elements;knk-2 reactor;pressure drop;reactor safety;testing;thermal hydraulics;transients
Components Category: --Fuel assemblies
display the document: 34087765.pdf
Results of experiments in the THIBO II test section Ergebnisse aus Experimenten in der THIBO II-Strecke
Bojarsky, E.;Deckers, H.;Lehning, H.;Piel, D.;Reiser, H.;Schmidt, LKernforschungszentrum Karlsruhe GmbH (Germany)
KFK-PSB--01.11.12P06C - German - 1989
Abstract: It was possible to prove in 1988 in the course of the THIBO I experiments. That under certain operating conditions thermohydraulically induced rod damaging oscillations may occur in sodium cooled Mark II fuel elements. Since May 1989 another THIBO II test series has been performed in a new test section of the sodium loop of the IMF III. The area of the coolant channel was reduced to approximately half its previous surface so that the thermohydraulic conditions come very close to those prevailing in the KNK II reactor. The experiments have shown that even with minor sodium enthalpy raises and low rating, respectively, motions of the fuel pins can be induced. This applies also in cases where the clearance of the pin in the spacer has been set to realistically low values
Key words: coolant loops;enthalpy;fuel pins;knk-2 reactor;mechanical vibrations;oscillations;sodium;thermal hydraulics
Components Category: Reactor components
display the document: 34086306.pdf
THIBO-Experiments: Thermohydraulically Induced Fuel Rod Oscillations in Sodium Cooled Reactors
Bojarsky, E.;Deckers, H.;Lehning, H.;Piel, D.;Reiser, H.;Schmidt, LKernforschungszentrum Karlsruhe GmbH (Germany)
KFK-PSB--18.04.04P04A - English - 1990
Abstract: The KNK II reactor in Karlsruhe experienced fuel element damages which could not be traced back to hydraulically excited vibrations. Instead, some indications pointed to low-frequency fuel rod oscillations caused by temperature differences over the circumference of the fuel rod as a result of the high specific rod power and the clearance of fuel rods in their spacers. In 1988, specific experiments were started in the sodium loop of the IMF III to investigate this phenomenon (THIBO experiments, THIBO standing for Thermal Induced pin BOwing). The rod movements were made visible and detected in a reproducible way. Since May 1989, another series of tests (THIBO II) have been run in a second test section. In this case, the cooling channel area was reduced so much that the thermal-hydraulic conditions approximated very closely those existing in the KNK II reactor. The experiments have shown that the fuel rods may start moving already at relatively low sodium temperature increases and low partial loads, respectively, even if the rod clearance in the spacer was set to realistically low levels
Key words: bowing;coolant loops;flow stress;fuel pins;fuel rods;knk-2 reactor;mechanical vibrations;oscillations;reactor kinetics;spacers;stress analysis;thermal hydraulics
Components Category: Reactor components
display the document: 34086308.pdf
Final Report THIBO-Experiments: Thermal-hydraulically excited fuel pin oscillations in sodium cooled fast reactors Abschlussbericht. THIBO-Experimente: Thermohydraulisch induzierte Brennstaboszillationen in Schnellen Natriumgekuehlten Reaktoren
Bojarsky, E.;Deckers, H.;Lehning, H.;Piel, D.;Reiser, H.;Schmidt, LKernforschungszentrum Karlsruhe GmbH (Germany)
KFK-PSB--18.04.04P04B - German - 1990
Abstract: The KNK II reactor in Karlsruhe experienced fuel element damages which could not be traced back to hydraulically excited vibrations. Instead, some indications pointed to low-frequency fuel rod oscillations caused by temperature differences over the circumference of the fuel rod as a result of the high specific rod power and the clearance of fuel rods in their spacers. In 1988, specific experiments were started in the sodium loop of the IMF III to investigate this phenomenon (THIBO experiments, THIBO standing for Thermal Induced pin Bowing). The rod movements were made visible and detected in a reproducible way. In 1989, another series of tests (THIBO II) have been run in a second test section. In this case, the cooling channel area was reduced so much that the thermal-hydraulic conditions approximated very closely those existing in the KNK II reactor. The experiments have shown that the fuel rods may start moving already at relatively low sodium temperature increases and low partial loads, respectively, even if the rod clearance in the spacer was set to realistically low levels
Key words: coolant loops;fuel pins;fuel rods;knk-2 reactor;mechanical vibrations;reactor kinetics;sodium;thermal hydraulics
Components Category: Reactor components
display the document: 34086309.pdf