Molten fuel

Lobachyov, K.V. and Richter, H.J. (1998). An Advanced Integrated Biomass Gasification and Molten Fuel Cell Power System, Energy Corners. Manage. 39. pp. 1931-1943. 

Lobachyov, K. V and Richter, H. J., An advanced integrated biomass gasification and molten fuel cell power system. Energy Conversion Manage 1998, 39 (16-18), 1931-1943. 

Physical separations Volatilization or distillation Fractional crystallization Extraction with liquid metals Chemical separations Liquid extraction with fused salts From molten fuel From liquid-metal solution of fuel Electrolysis through fused salts Partial oxidation... 

A. J. Suo-Anttila and I. Catton, The Effect of a Stabilizing Temperature Gradient on Heat Transfer from a Molten Fuel Layer With Volumetric Heating, J. Heat Transfer (97) 544-548,1976. 

Two CHLOE applications of interest in the context of this paper were the analysis of fragmentation experiments conducted as a part of LMFBR reactor safety studies of physical interaction of molten fuel or cladding... 

Mr Gratton gave a brief overview of some of the reactor safety research at Winfrith. Dr Wood discussed the results produced in the Molten Fuel Test Facility (METE) which is devoted to steam explosion experiments involving kilogram quantities of fuel. Dr Bird showed the newly commissioned Achilles Rig which investigates fuel pin behaviour. 

Total mass of molten fuel and structural materials (corium) in a 1000 MWe PWR ... 

A violent vapor explosion can result when a cold volatile liquid is suddenly brought into contact with a hot liquid. The explosion is due to the rapid vaporization of the cold liquid from heat transfer from the hot liquid. Such explosions are referred to as vapor, steam, physical, or thermal explosions rapid-phase-transitions (RPTs) (typically when referring to explosions involving cryogenic liquids) and molten fuel-coolant interactions (FCIs) when applied to nuclear reactor accidents. Accidental vapor explosions are frequent occurrences in the metallurgical, pulp and paper, and cryogenic industries. General reviews of the various aspects of vapor explosions can be found in Reid [1] and Corradini et al. [2]. 

The pins were irradiated in a TRIOX capsule of the HFR and two pin failures occurred at bumup levels of 6 at % (PuOj/CeOz pin) and at 10 at% (pin with 45% atPuO ). At present only results of the non-destructive examinations are available which show the existence of molten fuel in the case of the U-free pin (PuOj-CeOj) and fuel dislocation and temperature increase in the upper part of the pin with the high Pu content. The destructive examination is planned in the second half of 1997. 

During the nuclear reactor accident at Three Mile Island in 1979, an unknown mass of fuel pellets melted, and the molten fuel fell into water at the bottom of the reactor. Assume that the melting fuel pellets were pure UO2 and were initially at 900 C. Further assume that the water was initially at 8°C and that sensors indicated the final temperature of the water was 85°C. 

The goal of the LT2 test was to study internal molten fuel motion (fuel squirting) in TOP conditions no rupture was observed and the maximum energy deposit was 1.26 KJ/g. 

The goal of EFM1 was to study molten fuel motion and freezing in the voided coolant channel in TOP conditions and after clad rupture. 

Design Basis Accident analysis codes PREDIS and VENUS have been validated against European LOFA benchmark problems. Fuel subassembly worths at different radial positions in core during initial fuel loading were calculated. A study was made on the possibility of recriticality of molten fuel dropped in the core catcher from the core following an accident. Calculations of neutron irradiation dose for the reactor assembly out of core componets both in radial and axial locations were completed and indicated that the dose values are negligible ( ldpa). 

The problem of dealing with the consequences of CDAs - that can be possibly caused by unprotected transient over power (UTOP) and unprotected loss of flow (ULOF) - is an issue in the safety licensing process even though the occurrence probability is negligible. Conservative assumptions predict significant energy release by reactivity insertion due to the compaction of molten fuel. In SFR licensing process, primary coolant boundaries and confinement are required to accommodate the CDA consequences. 

Energy Release from Molten-Fuel Recriticality Accidents, Thomas P. McLau lin, Donald M. Peterson, William R. Stratton (LASL)... 

This report addresses itself to an extension of a previous study the major addition being the consideration of systems with Initial void fractions. Doth herein and in the aforementioned work it is shown that for reactivity insertion rates postulated for such molten-fuel rccrlticality situations in fast reactors, the explosive energy release is very small and typically a few orders of magnitude less than the fission (thermal) energy release. 

Although iodine and cesium are readily released from the fuel during core heatup and are expected to be removed by bubble dynamics in molten pools, frequently small fractions (3 to 10%) of these fission products remain in the molten and re-solidified fuel debris. The reason for this presence of volatile fission products in molten fuel debris is not yet fully understood, but the small surface-to-volume ratio of large pools and the possibility of chemical forms of cesium that are relatively stable at high temperatures may be contributing factors. This retention of smaller amounts of iodine and cesium in the molten material might be favored by rapid local heat-up, as would occur if the oxidation of Zircaloy by steam were a significant heat source. 

Cronenberg, A.W., Recent Developments in the Understanding of Energetic Molten Fuel Coolant Interaction , Nuclear Safety, Vol. 21, May-June 1980, pp. 319-337. 

Fletcher, D.F., The Particle Size Distribution of Solidified Melt Debris from Molten Fuel-Coolant Interaction Experiments , Nuclear Engineering fc Design, Vol. 105, Jan. 1988, pp. 313-319. 

Fletcher, D.F., Modelling Transient Energy Release from Molten Fuel Coolant Interaction Debris , AEE Winfrith Rept. AEEW-M2125, Dorchester, Dorset, U.K., 1984. 

The fraction of various groups of fission products >diich It Is assumed vlU be released from molten fuel Is shown In Table 9 3>... 

In another UTOP with 70 0 insertion, the 4S-LMR power rises and becomes stable at 1.30 of rated value. The tendency is the same as in a 1 insertion case the coolant temperature rises to 860°C and comes down to 800°C after the reactivity insertion is completed the peak fuel temperature is 940°C. If the transient lasts for hours, the fuel elements may be damaged resulting in molten fuel dispersion due to the iron atom diffusion and the liquefaction. 

Operation and maintenance (O M) costs of the MSR could be almost the same or less than those of the LWR according to the publications, although the MSR would need remote maintenance because molten fuel salt of high radioactivity circulates outside the reactor vessel. However, the MSR can operate longer than the LWR and save the downtime. 

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