摘要:

The effective temperature of the thermal neutrons at the center of the internal column of the Thermal Test Reactor has been measured by means of a danger coefficient technique. Assuming that the thermal neutrons have a Maxwellian velocity distribution, the experiments indicated that the TTR neutrons have a Kelvin temperature of 300°. The unique relation which exists between a 1/vand a non 1/vneutron absorber for neutron capture as a function of energy is the underlying principle upon which the experimental technique is based. The physical temperature of the reactor during the period of experimentation was also measured as 300°K.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15567

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

An analytical procedure is presented for evaluating and correlating various heat transfer and economic parameters in order to optimize core size and configuration in the design of heterogeneous reactors. Maximum wall temperature calculations are used to determine a large range of reactor operating conditions with core size and shape as parameters. Information gained from crossplotting such information may then be used to estimate the sensitivity of the cost of the reactor system to some operating variable such as coolant flow rate, again with core size as a parameter. This information, coupled with fuel cost data as determined from nuclear calculations, can then be used to select an optimum core size and optimum operating conditions for a given system.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15568

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

The uranium metal temperature coefficient of reactivity has been measured in ZEEP. A uranium sample was oscillated in the reactor and the resulting modulation of reactor power was measured as a function of the sample temperature. The temperature coefficient of uniformly heated uranium rods, 3.25 cm. in diameter, immersed in a constant temperature moderator (moderator-to-uranium volume ratio 22) is deduced from this experiment. Over the range +30°C to +230°C the coefficient isdk/dT=−(1.25±O.09)×10−5per°C. Over the range +10°C to−140°C the coefficient isdk/df=−(1.58±0.18)×10−5per°C.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15569

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

The thermal neutron fissionability of U239and Th233were measured in the Materials Testing Reactor. An upper limit of 20 barns was found for the thermal neutron fission cross sections of these two isotopes.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15570

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

An explanation of the dimensional instability of alpha-uranium under irradiation is advanced, based upon the anisotropic diffusion of lattice imperfections to grain boundaries and free surfaces. An approximate solution of the diffusion equations for an ellipsoidal grain is obtained, which predicts growth rate as a function of pile flux, temperature, and grain size. The calculations are applied to polycrystalline material and some comparisons made between theory and experiment, which confirm the feasibility of the suggested mechanism of dimensional instability.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15571

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

A method for using a saturating property to formulate a linear dosage scale is developed. The method is applied to the determination of the radiation damage rate for graphite in a nuclear reactor using the per cent decrease in electrical conductivity as the property. The damage rates in a number of irradiation facilities of the CP-3, CP-3′, and X-10 reactors are given. It is conclusively shown that the thermal neutron flux cannot be used to indicate the damage rate, for the one can be varied by more than an order of magnitude with respect to the other.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15572

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

Thorium tetrachloride is an important intermediate in the production of thorium metal. The readiness with which the hydrated salt hydrolyzes at high temperatures with its own water of hydration makes use of the anhydrous salt necessary for this purpose. The preparation of pure anhydrous thorium tetrachloride from aqueous solutions is very nearly impossible because of its hydrolytic behavior.The dry chlorination of the oxide, oxalate, carbonate, carbides, sulfides, and nitrate with various chlorinating agents has been evaluated on a laboratory scale. Chlorination of the oxide, oxalate, and carbonate in the presence of carbon and direct chlorination of the carbide with chlorine appear to be the most promising methods. The results of laboratory studies of the ThO2—C—Cl2, the Th(C2O4)2—CCl4—Cl2, and the Th(C2O4)2—CO—Cl2systems on a 1-lb batch scale are presented. Flowsheets, optimum conditions, and the thermochemistry of the reactions involved are discussed.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15573

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

The problem of transient conduction in an unclad fuel plate with negligible surface resistance was solved analytically for the case wherein simultaneous step changes are made in the volume distributed heat generation rate and the surface temperatures. The solutions for the central (maximum) fuel temperature and the space-mean temperature are presented in graphs. A solution for the case of an arbitrary number of successive step changes was obtained by superposition (example), and an approximate solution for the case of arbitrarily and continuously varying heat release rate and surface temperatures coupled to the reactivity was discussed.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15574

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

In various graphite piles, where one or two Ra-Be sources were producing a stationary neutron field, the neutron temperature was measured by activating an indium foil, sandwiched between two gold absorbers. The neutron temperature was found to be up to 70°C above the graphite temperature, which is explained by the incomplete thermal equilibrium.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15575

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

As a part of a program of reactor safety investigations, the response of a heterogeneous, water-moderated and -reflected reactor (SPERT I) to instantaneous reactivity additions has been studied experimentally with initial temperature of 20°C and initial power level of 5 watts. Excess reactivity additions from approximately O.3% to 1.4%, which result in asymptotic reactor periods from 10 sec to 7 msec, produced self-limiting power bursts with peaks up to 1300 Mw. Plots of the typical behavior of reactor power, fuel plate temperatures, and transient pressures for these tests are presented and discussed. Maximum reactor power, fuel plate temperature, pressure, energy release, and other quantities are correlated as functions of reactor period. The instantaneous excess reactivity of the system during the transient test has been computed from the experimental power behavior and typical results are shown. The reactivity compensation necessary to limit a power burst of this type has been determined and is discussed as a function of initial reactor period. Several mechanisms for the self-shutdown of the reactor are postulated and discussed in light of the experimental results.

ISSN:0029-5639    

DOI:10.13182/NSE57-A15576

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor