Determining Reactor Flux from Xenon-136 and Cesium-135 in Spent Fuel

The ability to infer the reactor flux from spent fuel or seized fissile material would enhance the tools of nuclear forensics and nuclear nonproliferation significantly. We show that reactor flux can be inferred from the ratios of xenon-136 to xenon-134 and cesium-135 to cesium-137. If the average flux of a reactor is known, the flux inferred from measurements of spent fuel could help determine whether that spent fuel was loaded as a blanket or close to the mid-plane of the reactor. The cesium ratio also provides information on reactor shutdowns during the irradiation of fuel, which could prove valuable for identifying the reactor in question through comparisons with satellite reactor heat monitoring data. We derive analytic expressions for these correlations and compare them to experimental data and to detailed reactor burn simulations. The enrichment of the original uranium fuel affects the correlations by up to 3 percent, but only at high flux.Comment: 10 pages, 9 figure

A novel reactor for determination of kinetics for solid catalyzed gas reactions

A novel perfectly mixed laboratory reactor for determining kinetics of heterogeneously catalyzed gas-phase reactions has been developed. Perfect mixing is achieved by circulating the gas in the reactor using an axial flow impeller in a well streamlined enclosure. Pellets are fixed in a rectangular opening in the blades of the impeller. They rotate with the impeller, thus realizing high particle velocities in the reactor. Interparticle mass transfer was studied experimentally by vaporization of naphthalene pellets. The mass-transfer coefficient in the novel reactor was found to depend on the velocity of a particle in the reactor. Mass-transfer coefficients in an internal recycle reactor at equal impeller tip speeds are 4-6 times lower than those in the novel reactor, and conditions can be chosen easily where at higher rotational speeds the mass- and heat-transfer rates are 8-10 times higher than in classical recycle reactors. The recycle flow rate in a recycle reactor was found to depend strongly on the resistance to flow caused by the catalyst bed itself. The novel reactor was tested under reacting conditions using the hydrogenation of ethene

Analysis and Kinetics of the Sequencing Batch Reactors

Fundamental analysis and kinetics of treatment reactors are major topics in environmental engineering literature. These fundamental topics in reactor processes are well known for the ideal batch reactor, the continuous stirred tank reactor, and the plug flow reactor. The sequencing batch reactors (SBRs) are relatively new in the field, but are widely used. Despite the wide application of sequencing batch reactors in the field, information is lacking on the fundamental analysis and kinetics, especially with comparison to the ideal batch reactor. This report presents analysis and kinetics of the sequencing batch reactors and compares the kinetics equations developed with those of the ideal batch reactor especially for zero-order, first-order, and second-order reactions. A significant result is that the SBRs’ equations for the three re- action orders analyzed become the equations for the ideal batch reactor if the entire reactor volume of a sequencing batch reactor is decanted. The fundamental analysis and the kinetics presented will help enhance the understanding of the sequencing batch reactors and their use in waste treatment

Incorporation of statistical distribution of particle properties in chemical reactor design and operation: the cooled tubular reactor

Pellet heat and mass transfer coefficients inside packed beds do not have definite deterministic values, but are stochastic quantities with a certain distribution. Here, a method is presented to incorporate the stochastic distribution of pellet properties in reactor design and operation models. The theory presented is illustrated with a number of examples. It is shown that pellet-scale statistics have an impact on cooled tubular reactor design and operation. Cooled tubular reactor design is determined to a large extent by the objective that run away inside the reactor tubes be avoided. We obtain the highest conversion if conditions in the tubes are such that the pellet and reactor run-away mechanisms are in balance. This determines an optimum amount of particles on a diameter inside a cooled tubular reactor. This optimum is influenced by the distribution of transport coefficients over the pellets. Because of the pellet-scale statistical behaviour, a certain percentage of the tubes will always suffer run away if we operate close to the run-away region. If we have certain fluctuations in the coolant temperature, reactor pressure or load, any of these can damage a certain amount of tubes. As these fluctuations occur often, the performance of the cooled tubular reactor will deteriorate with time. The effects, as shown in this study, may cause an increase in inherent reactor instability. Therefore, if these effects are taken into account, a more conservative reactor design emerges

A simple model of reactor cores for reactor neutrino flux calculations for the KamLAND experiment

KamLAND is a reactor neutrino oscillation experiment with a very long baseline. This experiment successfully measured oscillation phenomena of reactor antineutrinos coming mainly from 53 reactors in Japan. In order to extract the results, it is necessary to accurately calculate time-dependent antineutrino spectra from all the reactors. A simple model of reactor cores and code implementing it were developed for this purpose. This paper describes the model of the reactor cores used in the KamLAND reactor analysis.Comment: 14 pages, 7 figures, submitted to Nuclear Instruments and Methods in Physics Research