摘要:

AbstractFew-group analysis is applied to a variety of D2O-U235critical assemblies. Use of relatively simple prescriptions for obtaining group constants is sufficient to give good values of the reactivity over a wide range of concentrations of U235in D2O. Among these simple prescriptions is one which attempts to take into account the spatial variation in the neutron spectrum in reflected systems. Use of this prescription improves the calculated reactivity by about 5% over that obtained with only a single thermal neutron spectrum characteristic of the core.

ISSN:0029-5639    

DOI:10.13182/NSE8-1-1

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractA thin cadmium rod, corresponding to a control rod in a reactor, was placed diagonally in a cylinder containing water. The change in time decay constant of the neutron flux was measured and interpreted as a change in the geometric buckling of the system. The measurements were performed for various ratios of height to radius of the cylinder. The results were compared with calculations where the effective thickness of the rods was estimated in two different ways and the total effect of the rods was obtained by a weighting procedure. The measured values fell between the two calculated curves.

ISSN:0029-5639    

DOI:10.13182/NSE8-1-12

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractIn order to investigate the design and fabrication problems inherent in compact, high-performance heat exchangers for aircraft nuclear propulsion applications, extensive development testing was done by the ANP Division of the Oak Ridge National Laboratory on bifluid (molten salt-NaK) heat exchangers and on liquid metal (NaK-air) radiators. These test units were prototypes of the heat transfer equipment which was to be used in the Aircraft Reactor Test at ORNL. Five bifluid test loops and one liquid metal test loop were used for performance and endurance testing of these components at simulated reactor operating conditions. The molten salt used was a sodium-zirconium-uranium fluoride mixture of composition NaF—50 mole %, ZrF4—46 mole %, UF4—4 mole %. The NaK used was 56 wt % sodium and 44 wt % potassium. A total of 47,000 hr of operation at 1200–1700°F was accumulated on 18 heat exchangers and 20 radiators. The program demonstrated that the compact heat exchanger geometries tested possessed the performance capabilities and mechanical integrity to meet ART design requirements.

ISSN:0029-5639    

DOI:10.13182/NSE8-1-14

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe thinking and experience that went into the ORNL-ANP heat exchanger development program for high-performance heat exchangers has brought out many points having broad implications for other types of high-temperature heat exchanger. This paper summarizes the design precepts and philosophy on which this work was based.While it is evident that weight and volume are vitally important in aircraft power plants, there is also a strong incentive in stationary and marine power plants to reduce both weight and volume because of such considerations as shielding, remote handling, liquid inventory, reactor hazards, control response rates, costs, etc. Analysis disclosed that the tube diameter should be as small as possible consistent with limitations imposed by deposits on the tube walls. Test experience demonstrated the practicality of tube diameters from¼to⅛in. o.d.It was found that thermal stresses imposed the most important single set of fundamental limitations on the heat exchanger design, and that thermal strain cycling associated with changes from low to high power was the most important failure mechanism. This, coupled with leak tightness requirements, made it essential that a ductile material be employed. The metal also had to be well suited to both welding and brazing because the only thoroughly satisfactory tube-to-header joints tested were first welded and then back-brazed.A series of heat exchangers designed according to these precepts was built and endurance tested at power densities as high as 10 Mw/ft3(350 kw/liter). Many of the units were endurance tested for over 1000 hr at temperatures up to 1500°F.

ISSN:0029-5639    

DOI:10.13182/NSE8-1-21

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractHeat transfer and pressure drop test data were obtained on liquid metal-to-molten salt heat exchangers and on liquid metal-to-air radiators. The data were correlated to permit predictions of the heat transfer and pressure drop performance of heat exchange equipment to be used on the Aircraft Reactor Test scheduled at the Oak Ridge National Laboratory. The test results agreed well with analytical predictions using the Dittus-Boelter and Kaufman-Lubarsky equations except that in the transition region from laminar to turbulent flow marked differences were found in the heat transfer coefficients for flow through round tubes and axial flow between tubes. These differences appeared to stem in part from the irregular geometry of the flow passage between tubes, and in part, from the tube spacers employed.

ISSN:0029-5639    

DOI:10.13182/NSE8-1-32

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe diffusion equations associated with the multigroup, multiregion problem are solved by expansions in eigenfunctions which are solutions of the Helmholtz equation. A determinantal criticality equation is exhibited in which the order of the determinant is independent of the number of groups and which can be solved without recourse to complicated computational procedures. Moreover, the need to fulfill explicitly the requirements that the flux and current associated with each neutron group be continuous across interfaces is eliminated.

ISSN:0029-5639    

DOI:10.13182/NSE8-1-44

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractSpectrum and variance of“pile noise”are discussed according to the formulation of S. O. Rice. It is shown that variance diverges as criticality is approached. A convergent quantity closely related to variance is introduced and observations on this quantity taken with ZPR-IV′, a light water-moderated highly enriched source reactor at Argonne.

ISSN:0029-5639    

DOI:10.13182/NSE8-1-53

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe diffusion length of thermal neutrons has been measured in water over the range 25.9 to 295.3°C in the pressure vessel of the KAPL High Temperature Critical Assembly. The diffusion length was determined by fitting an exponential to the data found by activating manganese foils with neutrons from a small Sb-Be source. The temperature variation of the diffusion length could be fairly well represented by either of two simple approximations—either that the transport cross section of water has a 1/υbehavior, or that the transport cross section is determined from the Radkowsky prescription.

ISSN:0029-5639    

DOI:10.13182/NSE8-1-62

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractA study has been made of available experimental data for the cross section and fission parameters for U233. These data have been used to arrive at recommended values of the parameters for 2200 m/sec neutrons as follows:σnT= 586±2 b;σn,n= 13±3 b;σnX= 573±4 b; 1 +α= 1.0935±0.0038;σn,f= 524±4 b;σn,γ= 49±2 b;η= 2.291±0.009;2.50±0.012. The methods used in deriving the recommended values are presented in detail and brief summaries of the measurements are included. Energy dependent absorption and fission data from 0.02 to 1 ev that have recently become available are presented.

ISSN:0029-5639    

DOI:10.13182/NSE8-1-66

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE60-A25779

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor