ISSN:0550-3043    

DOI:10.13182/NT70-A28658

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

A study was initiated to determine the highest235U enrichment that could be processed safely in a facility originally designed for refining natural uranium ores and concentrates. The equipment used in converting uranyl nitrate to uranium trioxide was determined to be the limiting factor.Calculations of neutron multiplication throughout the denitration cycle were made using data from the analysis of process material. It was determined that the maximum235U enrichment could be safely increased to 2.0% from the previous limit of 1.25%235U. Processing at the higher enrichment required slight changes in equipment to ensure against moderation of the material.

ISSN:0550-3043    

DOI:10.13182/NT70-A28647

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

A vacuum-pressure pulsing process was developed to gas impregnate graphite with carbon. An inductively heated graphite substrate is cycled between vacuum and 20-psig butadiene for 2 to 30 h at 750 to 950°C. The vacuum and pressure pulse periods were, respectively, 0.5 to 1 sec and 7.5 to 60 sec. Weight increases up to 8% were achieved in graphite of original density 1.86 g/cm3, and helium permeabilities were reduced from>10−2to<10−8cm2/sec, as required for molten-salt breeder reactor application.

ISSN:0550-3043    

DOI:10.13182/NT70-A28648

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

The use of Pu as a makeup fuel in D2O-moderated thorium converters is investigated. The reactor starts with plutonium, the bred233U is reprocessed and fed back into the system. During reactor life there is a considerable change in fissile composition. The physics calculations follow the reactor through the whole running in period from the first core into a quasi-equilibrium state. For this type of system, the running in period makes an important contribution to the overall merits of the reactor. The physics of the Pu burner is compared in detail to a similar reactor using235U as makeup fuel.The evaluation of fuel-cycle costs is performed with present worth methods, calculating quasi-equilibrium costs and average fuel-cycle costs for the reactor lifetime, running in period included.Thorium systems, starting and running with plutonium makeup, have to pay rather high penalties for the first refueling periods. The Pu value is estimated to be in the range of $9/g fissile.

ISSN:0550-3043    

DOI:10.13182/NT70-A28649

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

Bare (U, Th)O2fuel pellets were irradiated in a graphite structure to evaluate the potential of this type fuel for high-temperature gas-cooled reactors. The maximum fuel temperature was 1650°C at fuel pellet centers and 1370°C at fuel pellet-tographite interfaces. The experiment was terminated when fission-gas release rates increased by an order of magnitude and the radial temperature gradient from the fuel pellet centers to outer edges increased from 335 to 390°C.Postirradiation evaluation showed no evidence of chemical reaction or incompatibility between the fuel and the surrounding graphite. The graphite underwent no significant changes, but most of the fuel pellets were severely fractured. Burnup (2.4% heavy metal) was below that where the fuel swelling would be expected and optical measurements of two intact pellets showed no dimensional changes.

ISSN:0550-3043    

DOI:10.13182/NT70-A28650

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

A processor-oriented gamma-spectrometer system for the rapid and efficient acquisition of radiological data is described. Gamma spectral data are accumulated and operated upon in the same unit to arrive at activity levels for the gamma-emitting radionuclides in the sample.A comparison is made between the operational aspects of the conventional hard-wired analyzer and the processor-oriented system. It is shown that this type of system provides increased flexibility as well as more rapid processing and reporting of data.

ISSN:0550-3043    

DOI:10.13182/NT70-A28651

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

A pulse-mode neutron detection system designed for reactor noise measurements was characterized and compared with conventional current-mode noise measurement systems. Pulses from a proportional counter with a 60-nsec electron collection time were amplified and applied to a discriminator and thence to a counting-rate circuit with a time constant of 15µsec. Statistical fluctuations in the counting-rate voltage were frequency analyzed.Under conditions of negligible gamma flux and counting loss, the pulse system yielded frequency spectra indistinguishable from ion-chamber spectra. The results were not very sensitive to counting loss up to at least 20%, but the effect of counting loss limited the ultimate useful neutron flux for the system tested to<2×106n/(cm2sec). Space charge and gamma pileup in the detector controlled the performance of the pulse system in high gamma fluxes; the pulse system performed better than the best available current system over a limited range of neutron-and gamma-flux intensities.Because of its shorter time constant, the pulse-mode system can be used to measure power spectral density at much higher frequencies than the current-mode system. Thus, the pulse-mode system appears to be the more attractive for fast reactor subcriticality measurements.

ISSN:0550-3043    

DOI:10.13182/NT70-A28652

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

The increasing availability of high-strength252Cf neutron sources for educational use suggests the possibility of a new wave of source-strength measurements in student laboratories. In this paper, different methods for calculation and measurement of strengths have been discussed. Results obtained by the maganese-boron method have been compared with the theoretical predictions. Sources of error have been pointed out and a procedure has been recommended for use in a laboratory. It is concluded that results obtained by this method are accurate to 5% while more elaborate and painstaking measurements may produce ~2% accuracy.

ISSN:0550-3043    

DOI:10.13182/NT70-A28653

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

A238Pu-Powered heat source for use in an experimental model of a cardiac pacemaker was developed. The encapsulated source has a thermal power of 0.134±0.013 W and is fueled with three238Pu metal pins. Each fueled pin was TIC welded into a tantalum inner capsule. The inner capsules were electron beam welded into Hastelloy-C middle capsules. These middle capsules were platinum plated to prevent a reaction between the Hastelloy-C and the titanium outer capsules. Three middle capsules were electron beam welded into each outer capsule.

ISSN:0550-3043    

DOI:10.13182/NT70-A28654

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

ISSN:0550-3043    

DOI:10.13182/NT70-A28656

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor