摘要:

The reactivity worth of a plate-type fuel element at the center of a critical lattice of such elements has been experimentally determined by the pulsed-neutron method. This value has not been previously established because it is too large to be obtained by conventional inhour techniques. The value obtained for the Bulk Shielding Reactor-I Loading No. 78 wasΔρ= 6.1±0.5 dollars. Additional measurements of a configuration in which the central element was replaced by an element containing either one-half or three-quarters of a normal fuel element loading are discussed.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25879

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

An alloy containing niobioum-20 w/o uranium has been developed for reactor fuel applications. The fabrication characteristics, mechanical properties, and corrosion behavior in air, CO2, NaK, water, and steam were studied.After consumable arc melting, the alloy was successfully forged at 1370°C (2500°F) and rolled at 980°C (1800°F) to sheet. Representative specimens of this alloy showed onlv slight reductions in hardness up to 900°C (1650°F). The 0.2% offset yield strength was 93,000 psi at 24°C (75°F) and 71,000 psi at 870°C (1600°F). At a stress of 63,000 psi at 870°C (1600°F), 200 hr were required to cause rupture.The corrosion life of niobium-20 w/o uranium was superior to that of unalloyed niobium in 300°C (572°F) air and in CO2at 316°C (600°F). In 1000 hr of exposure to 316°C (600°F) water, this alloy exhibited corrosion rates only two or three (0.003 mg/cm2/hr) times greater than that of Zircaloy-2 (0.001 mg/cm2/hr). This alloy appears to be compatible with NaK at 870°C (1600°F.)

ISSN:0029-5639    

DOI:10.13182/NSE61-A25880

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

The time-dependent energy spectra, for times greater than the slowing-down time, were generated in a monatomic heavy gas with the help of a multigroup formalism. These spectra were obtained for the infinite as well as finite media of beryllium and graphite. The behavior of asymptotic energy spectra during the last stage of neutron thermalization and diffusion periods was studied. The thermalization time constant for the establishment of the final Maxwellian velocity distribution of neutrons, in a monatomic heavy gas, was estimated to be equal to (1.176ξΣs0υ0)−1. Total thermalization times for neutrons in beryllium and graphite were found to be equal to 114 and 238µsec, respectively. Using the energy-dependent transport mean free path, the diffusion cooling coefficient for beryllium was calculated to be equal to 0.890 cm2For graphite, under the constant diffusion coefficient assumption, the diffusion cooling coefficient was determined to be equal to 1.922 cm2.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25881

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

The performance of some blanket designs is studied using economically optimized cycling based on a simple economics model. For an 800-liter core fast reactor having a 45-cm radial blanket and an average core power of 1-Mw per liter, it appears that the outermost blanket elements make enough plutonium to pay for the cost of their fabrication and processing, unless the core power density falls well below the expected value. A cyclic motion of elements in the inward radial direction has little effect on the economics if optimum cycling is followed. Moving the blanket elements may have engineering advantages however, such as a uniform buildup and burnup, and less variation in power locally with time. A paste blanket with radial inward motion and axial mixing has a similar behavior.Inclusion of moderating material in a fast reactor blanket is not promising for a high-power density reactor using optimum cycling, but it may prove valuable if blanket fluxes get very low or the residence times of the blanket elements are limited.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25882

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

The development and compilation of formal solutions to heat transfer problems which occur in reactor design is an important phase of reactor engineering. Formal analytical solutions are useful both for making first approximations and as a check of more detailed work. Three solutions to three different cases of transient heat transfer in a conduit cooled on the inside by a flowing coolant are presented. The heat transfer mechanism is described by a pair of coupled partial differential equations applicable to nuclear reactor design and analysis.The first solution is for the case of coolant flowing at constant velocity through a conduit with internal heat generation a function of distance. The heat transfer coefficient from conduit to coolant is infinite for transfer so that the conduit and coolant temperatures are always equal. The coolant inlet temperature varies with time. All physical properties of the coolant and conduit are taken as constant. Four specific sets of conditions are considered.In the second case the coolant inlet temperature is constant, the heat transfer coefficient is infinite, the internal heat generation is a function of distance, and the coolant velocity decreases with time, as on loss of pumping power. Three specific sets of conditions are considered.The third case is the same problem as case one except that the heat transfer coefficient between the conduit and coolant is finite.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25883

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

In reactors fueled with thorium, increasing specific power leads to reduction of fuel reactivity lifetime and conversion ratio because of the appreciable decay time and neutron absorption cross section of Pa233. A generalized study of these effects in thorium-U233fueled reactors has been carried out using a simplified reactor model.It was found that the most important specific power effect on fuel reactivity is the holdup of Pa233, rather than its burnout to U234. Using conventional cost bases, the effect of specific power on the fuel costs for thorium fueled reactors has been shown to be small in the range of practical specific powers.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25884

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

The resonance fission integrals of U235, Pu239, and Pu241have been measured relative to the gold resonance capture integral by the cadmium ratio method. The cadmium ratios were measured in a reactor at a position where the epicadmium flux spectrum was closely 1/Eexcept for a peak above 25 kev. A small spectrum correction was made for this flux peak to infer the fission integral over a pure 1/Espectrum using a calculated epicadmium flux spectrum. The resonance integrals obtained were, with a 0.5-ev cutoff energy, 274±11b, 327±22b, and 557±33bfor U235, Pu239, and Pu241, respectively.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25885

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

A compact forced-circulation test loop for obtaining corrosion data applicable to molten-salt-fueled reactors has been operated in the MTR (HB-3) beam hole. Several tests were conducted with two fused-salt mixtures, NaF-ZrF4-UF4and Li7F-BeF2-UF4, in loops constructed, respectively, of Inconel and INOR-8 (nominal composition: 70% Ni, 16% Mo, 7% Cr, 5% Fe, 2% other alloying elements). The maximum loop temperature ranged from 1300 to 1600°F. Engineering aspects of loop design and operation are described.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25886

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

In the analysis of a reactor space-time problem by the method of modal expansion, the labor is reduced and accuracy improved if the modes are chosen such that the expansion has the property of finality. Modes having this property are identified for a zero power (no feedback) reactor and for a reactor with linearized xenon feedback.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25887

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

The study of reactor control systems for large excursions has presented considerable difficulty on both analog and digital computers. Two simple transformations are derived which permit an accurate solution of such systems over many decades on an analog computer.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25888

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor