摘要:

A simple, stable, time-optimal digital control program has been developed with general application to zero- or low-power nuclear reactors for power-level changes, especially power increases. The program is required to increase the power level while maintaining a minimum allowed period, and to reach the demand power with little or no overshoot. A switching criterion was derived using a discrete version of the Pontryagin Maximum Principle. The switch point was found to be dependent upon the minimum allowed period and the maximum reactivity removal rate of the controlled regulating rod. The control program developed was applied to digital simulation of three reactor models and was adapted for use on the Argonne Thermal Source Reactor (ATSR) for power-level changes. The maximum overshoot experienced was∼1% for various minimum allowed reactor periods and reactivity removal rates.

ISSN:0550-3043    

DOI:10.13182/NT70-A28685

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

The fission-gas release from pyrolytic-carbon-coated fuel particles was measured during irradiation, and the damage to the coating material and to the fuel was studied by postirradiation metallography. These particles were either uranium oxide, uranium carbide, or thorium-uranium carbide with a porous carbon primary coating. Particles coated with dense pyrolytic carbon and those coated with a combination of pyrolytic carbon and silicon carbide layers performed well during irradiation in the 1250 to 1400°C range, but both suffered severe internal reactions in the 1650 to 1700°C temperature range, even at low burnup. With one exception, all the experiments were conducted at a much higher burnup rate than would be encountered under normal power reactor conditions.

ISSN:0550-3043    

DOI:10.13182/NT70-A28686

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

A 0.357-o.d. null-balanced pressure transducer was designed and built for 900°F at 350-psig service and tested on the bench for seven months at design conditions and 1200 and 1300°F at 350 psig until failure six weeks later. This type transducer was also tested in conjunction with a fuel irradiation experiment in the CP-5 research reactor. It provided experimentors with fission gas pressure readings until failure of the fuel pin.A unique device was used to control the reference gas pressure. Control was obtained by making use of the change in probe-disk electrical contact resistance. This method allowed the transducer to follow increasing and/or decreasing pressures easily and quickly as it took place. Transducers of this type generally operate on the probe, making and breaking contact with the disk which makes it easy to follow increasing pressure but becomes difficult to follow decreasing pressures.Resolution of the system was found to be±l/4 psig with an overall accuracy of±8 psig for full range.

ISSN:0550-3043    

DOI:10.13182/NT70-A28687

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

An equation has been derived to compare the costs of two schemes for recycling spent fuel to light-water reactors: diffusion and blending. The calculations show that blending is slightly more costly than diffusion. The factors that can chiefly influence this conclusion are the discharge enrichment and the value of236U. A very high burnup would favor diffusion; a very high price for238Pu and, therefore, for236U, would render blending the desirable route.

ISSN:0550-3043    

DOI:10.13182/NT70-A28688

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

A small-scale semicontinuous pilot plant for studying chemical reactions carried out in remote environments is described. The all-stainless system features modular construction enabling rapid exchange of various elements. The equipment design permits purification, sampling, and other manipulative tasks to be performed in a“safe”operating area. Dissolved gases and moisture are removed from the reactant mass prior to circulation in the primary reaction loop. In this particular application, moisture is removed by low-temperature adsorption on molecular sieves. Progress of the drying is monitored continuously by a commercially available instrument in which moisture passes through a semi-permeable foil to a capacitance element. The rate of reaction in the remote reaction zone is reflected continuously in the time rate of change of conversion as measured by in situ differential refractometry. Utilization of this system has permitted accurate measurement of the rate of60Co radiation-induced polymerization under super-dry conditions.

ISSN:0550-3043    

DOI:10.13182/NT70-A28689

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

Gamma-ray flux-to-dose-rate conversion factors obtained with a philosophy consistent with that used for neutrons have not been generally available. To eliminate this inconsistency and develop more realistic gamma-ray conversion factors, gamma-ray dose-rate distributions were determined in a slab phantom.Calculations were made with the discrete ordinates code ANISN and by the Monte Carlo code OGRE. Agreement between calculations and the available experimental results was excellent. Based on these results, a recommended curve was prepared for use when low-level exposure is the consideration.

ISSN:0550-3043    

DOI:10.13182/NT70-A28690

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

A theoretical treatment of on-stream activation analysis is given based on the nuclear and flow phenomena involved. A dilute solution of natural uranium in water is considered for illustrative purposes and to demonstrate the application of the mathematical models developed to a practical analytical problem. However, the underlying principles and the mathematical treatment are quite general and are equally applicable to on-stream activation analysis of similar systems. In a subsequent paper, experimental measurements in uranium and thorium solutions will be reported.It is shown that an arrangement in which continuous plug flow of a fluid stream is irradiated and counted simultaneously will lead to the highest count rate at a given concentration of the element under analysis. Cases of interrupted and well-stirred flow conditions are also studied and compared. Continuous and pulsed irradiation and counting arrangements are also compared and the advantages and shortcomings of each system are discussed.

ISSN:0550-3043    

DOI:10.13182/NT70-A28691

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

A neutron activation analyzer utilizing an isotopic neutron source is described. The analyzer has been installed at a chrome concentration plant for off-line process control. Silicon, chromium, and aluminum can be determined simultaneously in chrome concentrates, ore samples, etc. Results obtained are described and further applications of the activation analyzer of this type in the glass, ceramic, and cement industry are discussed.

ISSN:0550-3043    

DOI:10.13182/NT70-A28692

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor