摘要:

AbstractReactivity effects of large voids in the reflector of the Pool Critical Assembly, an enriched-uranium, light-water-moderated and -reflected reactor, were investigated. The four reactivity effects studied were (1) variation of reactivity with void size, (2) variation of reactivity with void position on the core-reflector interface, (3) variation of reactivity with the distance between the void and the core, and (4) superposition of void reactivity effects. The variation of reactivity with void size and position on the core-reflector interface was correlated by a statistical weight correlation. An approximate theoretical method based on two-group diffusion theory was developed for calculating both the effect on reactivity and the effect on the neutron flux for a void covering one entire face of a reactor having a rectangular parallelepiped core. The calculated effects on reactivity and on the thermal-neutron fluxes were in reasonable agreement with experimental results.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25691

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe Greuling-Goertzel method is applied to calculation of the slowing down of neutrons in deuterium, and the results compared with the Selengut-Goertzel method, in which the deuterium slowing-down is treated by age theory. It is shown how existing codes for calculating slowing down in hydrogen can be modified in a simple manner to incorporate this treatment of deuterium. Numerical results show excellent agreement between measured and calculated ages, and indicate that a continuous slowing-down model for deuterium is inappropriate. This is in qualitative agreement with the experiments performed by Wade, and in disagreement with Olcott's work. However, it is shown that an age kernel with an age to indium of 100 cm2may be used to compute the fast leakage from heavy-water systems over a wide range of buckling. The situation concerning agreement with critical experiments remains to be clarified because of large uncertainties in other criticality factors.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25692

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractIn building a nuclear reactor of any type, the stage is reached at which a decision must be made as to what steels can be used in construction of each plant component. Nuclear engineers have recognized the limitations of some of the common steels in nuclear environments and are pointing out ways the steelmaker should go in devising steels with the nuclear and chemical properties more compatible with them.Methods of fabrication, mechanical property data and compositions of carbon and alloy, including low manganese, low residual element steels made for possible nuclear uses are summarized and compared with those of standard grades of carbon and alloy steels.The limitations on composition imposed by nuclear considerations, and selected data on experimental and commercially produced steels made to avoid these limitations, are outlined. Low manganese steels are commercially available; should the need arise, other compositions both carbon and alloy that are now experimental could be made.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25693

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractA transfer function for the heat release in cylindrical fuel elements is derived. The time constants of the transfer function are given in curves as a function of the fuel element rod radius and thermal conductivity of UO2. The average fuel element temperature, needed in connection with Doppler effect, is given as a function of the heat release transfer function parameters. Coolant temperature variations are taken into consideration.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25694

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractApproximate methods, which are simple and quick to use, are presented for finding the response of a critical and a subcritical reactor, to ramp inputs ofδk. The solutions are based on one equivalent group of delayed neutrons. Various methods of selecting the equivalent delayed neutron decay constant are discussed and it is shown that a one-group model will always be conservative if a particular method of selection is used. It is also demonstrated, that the approximate solutions are more accurate than the well-known approximation proposed by Newson.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25695

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractCritical assemblies reported here consist of approximate spheres of enriched-uranium hydride composition (approximating UH3) in 8-in. thick normal uranium and nickel reflectors and in a uranium reflector with nickel liner. Data are of the following types: (1) critical sizes, (2) values of Rossi alpha in the neighborhood of delayed critical, (3) activation rates of various internal neutron detectors, and (4) reactivity coefficients of a variety of elements. From the reactivity coefficients at various radial positions, changes in critical mass corresponding to small changes in composition and density are computed.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25696

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractUsing transport theory in the cylindrical fuel region of a heterogenous reactor, Amouyal and Benoist have proposed new formulas to compute the disadvantage factors used in the determination of the thermal utilization factor. The same method when applied to an infinite slab geometry gives simple expressions for the fuel and moderator disadvantage factors.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25697

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractA method of calculating space-dependent reactor kinetics by direct numerical integration of the time-dependent multigroup equations is described. In particular, this method is applied to study the buildup and decay of neutron flux in a subcritical reactor with a step-function point external source.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25698

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe slowing down density,q, of neutrons in a reactor may be decomposed into a sum of parts due to various nuclear specieshaving corresponding scattering cross sectionsµs1,µs2,···. An approximate relation betweenqiand isotropic fluxφ(u) (whereuis the lethargy) is proposed..The values ofγiandξiare derived and interpreted.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25699

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe methods used for fabrication of finned aluminum-clad flat plate fuel elements are discussed. Uranium—3.5 w/o Molybdenum alloy core plates were fabricated by vacuum casting in graphite molds. The uranium alloy plate was electroplated with nickel and inserted into an extruded aluminum sheath containing external fins. Aluminum end plugs were inserted to complete the fuel plate assembly. A core-to-cladding metallurgical bond was obtained by hot gas pressing (isostatic pressing) the assembly. Bonded plates were end machined, inspected, stacked, clipped, and loaded into a stainless steel container box. Cast stainless steel end hardware was then affixed by heliarc welding to the respective box ends to result in the completed fuel element.Methods for process control are discussed. Preliminary irradiation results are presented which indicate that the elements produced by the described process are suitable for organic moderated reactor use.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25700

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor