摘要:

The prompt neutron period of a bare sphere of U235has been measured at two reactivities between delayed and prompt critical. The x-ray burst from a betatron was used to establish the initial neutron population in the critical assembly, and the neutron intensity was observed by photographing oscilloscope traces of pulses from a spiral fission chamber. The values obtained forα, the reciprocal of the prompt neutron period, are—0.52±0.03×106sec-1at 54 cents reactivity, and—0.26±0.03×106sec-1at 76 cents.

ISSN:0029-5639    

DOI:10.13182/NSE58-A15492

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

Cerium-141 and cerium-144 are determined in the presence of each other by performing a suitable cerium chemical separation and then measuring the radiation from each nuclide. Cerium-144 is determined by counting the 3.0-Mev Pr144beta ray; cerium-141 is determined by integrating beneath the 145-kev gamma-ray peak observed with a sodium iodide gamma-ray spectrometer. In the later case correction for contributions from cerium-144 must be made. The gamma/beta branchings for the 145-kev gamma ray in cerium-141 and the 134-kev gamma ray in cerium-144 were determined.

ISSN:0029-5639    

DOI:10.13182/NSE58-A15493

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

An experiment was conducted in a critical assembly to determine water channel power peaking in a heterogeneous, highly enriched, water-moderated reactor subassembly. In addition to horizontal profiles of power density in a plane below a bank of control rods, data were obtained on the interacting effects of the control rod channel and bottom reflector power peaks. Experimental techniques are discussed.A computation for a comparable multiregion cell was made using a few-group diffusion theory digital computer code. Comparison of the results showed that variations in fast neutron spectrum and in manner of homogenization of materials within cell regions had no appreciable effects upon the power density peak. The choice of thermal neutron spectrum is important. Agreement between all experimental values and calculations with a Maxwellian spectrum was excellent. The comparison between experiment and calculations with a hardened thermal neutron spectrum was relatively poor.The results of this investigation indicate that great care must be exercised in interpreting experimental data on power distribution, and that two-dimensional diffusion theory calculations of power density are substantially verified. The use of U235monitor foils is recommended in order to obtain a true fission power distribution. It was found that variations in the water gap width of the order of 10% had negligible effect upon the horizontal peak-to-average power ratio in the fuel. The use of metallic control rod extensions was found to decrease the horizontal peak-to-average ratio substantially, the magnitude of the decrease verifying analytical predictions.

ISSN:0029-5639    

DOI:10.13182/NSE58-A15494

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

An approximation method is proposed for calculating the detailed kinetic response of a reactor during a transient in which the space and time behaviors of the neutron flux are not separable. In order to test the validity of the method a particular transient is studied for a series of cores chosen so that the space-time behavior of the neutrons is nonseparable in varying degrees. A particularly simplified mathematical description of the neutrons allows an exact solution to be obtained and hence affords a means of verifying predictions of the approximation scheme. Agreement between exact and approximate calculations is encouragingly good.

ISSN:0029-5639    

DOI:10.13182/NSE4-727

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

A fuel element consisting of plutonium and uranium oxide in steel tubing and capable of a large fraction of fuel burnup is described. As this fuel element makes possible recovery and refabrication with fewer steps than are required for a metal fuel element, lower recycle costs result. Breeders with fuel and fertile material in both oxide and metallic form were analyzed by the multigroup method on the UNIVAC for the purpose of comparing characteristics. A summary of the calculations is presented. The decrease in the breeding ratio resulting from the replacement of the metal core by oxide is only 0.2, a small effect in a future nuclear power economy where plutonium will have a low value as fuel rather than a high value as weapon material. Use of an oxide blanket may further reduce the breeding ratio by 0.05.An illustrative design is presented which has five atoms of uranium per atom of plutonium in the core and 45% sodium, a breeding ratio of 1.4 and a critical mass of 400 kg. Incremental refueling is assumed to reduce the control range required for 50% burnup of the original fuel loaded.

ISSN:0029-5639    

DOI:10.13182/NSE58-A15496

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

Many factors influence the design of a containment structure: size and shape of the reactor and other equipment to be housed, topographic and subsurface features of the site, proximity to populated areas, relative economy of construction materials, need for access during operation, and most important, pressure-volume duty. For a given duty, and for geometrically similar structures, the volume can often be varied over a broad range with little change in total cost. The upper limiting volume is reached when external forces rather than internal govern the design; the lower limit is usually the point where the membrane becomes unreasonably thick. Two or more small vessels connected together may have advantages over one large vessel, but additional design problems arise in making them act as a unit. The merits of total versus partial containment are discussed. A comparison is made of the various designs studied in selecting the containment vessel for the Dresden Nuclear Power Station. These included simple and composite structures, some above and some below ground, some designed for total and some for partial containment. A steel sphere for partial containment was selected as best suiting the needs of this project.

ISSN:0029-5639    

DOI:10.13182/NSE58-A15497

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

An exact expression for the reactivity effect of a control element placed in a reactor is derived within the limitation of validity of multigroup diffusion theory. The evaluation of the expression requires a knowledge of the flux distributions in the reactor with and without the element (s) inserted. Since the reactivity effect is stated in terms of the flux distribution in the perturbed and unperturbed reactors, one can calculate the effect of a control element if a good estimate for the form of the perturbed flux is made. A first-order perturbation calculation for thermally black control elements is presented. The perturbation calculation assumes that the fast flux is unaffected by the presence of the control element. The results are valid for a reactor in which the neutron age is large compared to the square of the thermal diffusion length and for a control element which is small compared to both the size of the reactor and the square root of the age.

ISSN:0029-5639    

DOI:10.13182/NSE58-A15498

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE58-A15499

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE58-A15500

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE58-A15501

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor