Lifetime of reactors

Fuel lifetime, mass balances offuel materials, design basis lifetime of reactor core, vessel ... 

Design service lifetime of reactor vessel, years 45... 

The design basis lifetime for structural materials is 35 years for a 6 and a 10 MW(e) system, and about 20 years for a 20 MW(e) system. The design basis lifetime of reactor vessel it is estimated at 35 years. 

In May 1988, a Level-1 PSA was undertaken as part of the general risk assessment at DOE facilities. Revision 0 was completed, and reviewed by BNL, DOE and contractors. The revised report was available July 1990 (Azarm, 1990). The broad objective of the HFBR PRA program is to enhance the safety and operational activities throughout the. remaining lifetime of the reactor... 

If one just concentrates on the radioactive material in SNF, the volume is very small, especially compared to waste from other power production practices. However, one can only discuss the separated radioactive material if it has undergone extensive reprocessing. If SNF is to be isolated, as in a place such as Yucca Mountain, with perhaps 70 miles of tunnels, the volume is that of the interior of this minor mountain. Isolation of up to 100,000 metric tons of SNF in Yucca Mountain means that for the United States, approximately all the SNF made to date and that expected in the operating lifetime of all current reactors can be put there. Approximately 2,000 metric tons of SNF are produced each year in the United States. Waste volume and placement depend on the amount of compaction and consolidation at the sites. The plans for the Yucca Mountain present a realistic and understandable picture of the volume of SNF. 

Where the mean lifetimes of the growing chains are short, narrower MWD s are produced than in a batch or plug flow reactor but the minimum Dp is 1.5 or 2.0 according to the mechanism of termination. Dp independent of Up and... 

Membranes in catalysis can be used to improve selectivity and conversion of a chemical reaction, improve stability and lifetime of the catalyst, and improve the safety of operation. The most well-known example is in situ removal of products of an equilibrium-limited reaction. However, many more ways of application of a membrane can be thought of [1-3], such as using the membrane as a reactant distributor to control the reactant concentration levels in the reactor, or performing catalysis inside the membrane and having control over reactant feed and product removal. 

Almost all flows in chemical reactors are turbulent and traditionally turbulence is seen as random fluctuations in velocity. A better view is to recognize the structure of turbulence. The large turbulent eddies are about the size of the width of the impeller blades in a stirred tank reactor and about 1/10 of the pipe diameter in pipe flows. These large turbulent eddies have a lifetime of some tens of milliseconds. Use of averaged turbulent properties is only valid for linear processes while all nonlinear phenomena are sensitive to the details in the process. Mixing coupled with fast chemical reactions, coalescence and breakup of bubbles and drops, and nucleation in crystallization is a phenomenon that is affected by the turbulent structure. Either a resolution of the turbulent fluctuations or some measure of the distribution of the turbulent properties is required in order to obtain accurate predictions. 

Mikroreaktoren sind so klein wie ein Fingerhut, Handdsblatt, May 1998 Steep progress in microelectronics, sensor and analytical techniques in the past transport intensification for catalysis first catalytic micro reactors available partial oxidation to acrolein partial hydrogenation to cyclododecene anodically oxidized catalyst supports as alternatives to non-porous supports study group on micro reactors at Dechema safety, selectivity, high pressure exclusion of using particle solutions limited experience with lifetime of micro reactors [236],... 

There is now a marked pause in the construction and deployment of new nuclear power plants. Although some construction of reactors continues in Asia and Eastern Europe, a de facto moratorium exists in the United States and in most of Europe, while in Sweden and Gennany the governments plan to shut down operating plants before the end of their normal lifetimes. The inhibitions on nuclear power development stem in large measure from environmental concerns, particularly concerns relating to reactor accidents and nuclear wastes. 

Moholkar et al. [11] studied the effect of operating parameters, viz. recovery pressure and time of recovery in the case of hydrodynamic cavitation reactors and the frequency and intensity of irradiation in the case of acoustic cavitation reactors, on the cavity behavior. From their study, it can be seen that the increase in the frequency of irradiation and reduction in the time of the pressure recovery result in an increment in the lifetime of the cavity, whereas amplitude of cavity oscillations increases with an increase in the intensity of ultrasonic irradiation and the recovery pressure and the rate of pressure recovery. Thus, it can be said that the intensity of ultrasound in the case of acoustic cavitation and the recovery pressure in the case of hydrodynamic cavitation are analogous to each other. Similarly, the frequency of the ultrasound and the time or rate of pressure recovery, are analogous to each other. Thus, it is clear that hydrodynamic cavitation can also be used for carrying out so called sonochemical transformations and the desired/sufficient cavitation intensities can be obtained using proper geometric and operating conditions. 

Closely related to the superheating effect under atmospheric pressure are wall effects, more specifically the elimination of wall effects caused by inverted temperature gradients (Fig. 2.6). With microwave heating, the surface of the wall is generally not heated since the energy is dissipated inside the bulk liquid. Therefore, the temperature at the inner surface of the reactor wall is lower than that of the bulk liquid. It can be assumed that while in a conventional oil-bath experiment (hot vessel surface, Fig. 2.6) temperature-sensitive species, for example catalysts, may decompose at the hot reactor surface (wall effects), the elimination of such a hot surface will increase the lifetime of the catalyst and therefore will lead to better conversions in a microwave-heated as compared to a conventionally heated process. 

The selection of a fixed bed Co-LTFT process supported the objective to apply the SMDS process for beneficiation of remote gas fields. The Co-LTFT catalyst has a useful lifetime of 5 years and the robustness of fixed bed reactor technology has been proven. For example, the fixed bed Arge Fe-LTFT process has now been in operation for more than 50 years at Sasol 1. 

Typical processing data for reactors with a carbon black output of 10000 t/a (1250 kg/h) of tread black and of 14 000 t/a (1750 kg/h) of carcass black are listed in Table 28. These data show that the total mass put through the reactor amounts to 10-16 t/h. Although this is done at high streaming velocities (up to 800 m/s) and high temperatures (up to 1800 °C), modern high-performance reactors have lifetimes of 2 years and more. 

Periodically, a portion of the fuel in a nuclear reactor is removed and replaced with fresh fuel. In the past, the average lifetime of fuel in the reactor was 3 years with one-third of the fuel being removed each year. More recently, attempts are being made to extend fuel lifetimes. 

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