Reliability reactors

A final point to consider is whether heat transfer in a tubular reactor is inherently different from heat transfer without reaction. Several workers have claimed that special correlations for the heat transfer parameters are needed for reliable reactor models. In a number of reactor studies [40], the maximum temperature rise was greatly overpredicted by the models used, but others have reported the opposite effect. These differences may have been caused by inaccurate kinetic equations or errors in the heat transfer parameters, but they were probably not due to a fundamental difference between heat transfer with and without reaction. It is true that in steady-state heat transfer tests, the local gas and solid temperatures are equal, whereas with an exothermic reaction, T, is greater than Tg. If the reactor analysis is based on Tg, the heat transfer rate will be slightly underestimated because of increased radiation and conduction. However, for moderate or high Reynolds numbers, convection is the major contributor to radial heat... 

FUNCTION Control Heat Generation This function refers to the necessity to / control the heat generation of the reactor so that fuel temperatures are not excessive. Since Criterion II limits exothermic chemical reactions, the sole requirement of this function is to assure reliable reactor shutdown. 

The steam-generator (SG) operates according to a multiple natural circulation scheme to produce saturated steam this offers the best lifetime and operating characteristics, e g., a reliable reactor operation at any power level, simplicity in maintenance of the liquid state of lead-bismuth coolant at low power levels, and simplification of the water chemistry regime of the SG ... 

Core design with enhanced safety and highly reliable reactor shutdown systems,... 

It has been shown that the technology can reach acceptable safety standards. There are always opportunities to improve safety, and improvements will continue to be made. It is becoming increasingly clear that safety and economics are not incompatible a reactor which is built and operated to high safety standards tends to be a reliable reactor which earns a good income. Fast reactors with sodium coolant have intrinsic safety advantages which already show in terms of low radiation doses to the operating staff. 

An engineering and technical support group shall be available to provide timely assistance and consultation. The group shall be of sufficient size and technical knowledge and competent in all disciplines important to safe and reliable reactor operation. The group shall assist in areas such as the following ... 

Although fluidized sand or alumina can also be used in the jacket of these somewhat larger reactors, the size makes the jacket design a problem in itself, hence these reactors are seldom used. An advantage of the jacketed reactor is that several—usually four—parallel tubes can be placed in the same jacket. These must be operated at the same temperature, but otherwise all four tubes can have different conditions if needed. This type of arrangement saves time and space in long-lasting catalyst life studies. Jacketed tubular reactors come close, but still cannot reproduce industrial conditions as needed for reliable scale-up. Thermosiphon reactors can be used on all but the most exothermic and fast reactions. 

In gradientless reactors the catalytic rate is measured under highly, even if not completely uniform conditions of temperature and concentration. The reason is that, if achieved, the subsequent mathematical analysis and kinetic interpretation will be simpler to perform and the results can be used more reliably. The many ways of approximating gradientless operating conditions in laboratory reactors will be discussed next. 

The most reliable recycle reactors are those with a centrifugal pump, a fixed bed of catalyst, and a well-defined and forced flow path through the catalyst bed. Some of those shown on the two bottom rows in Jankowski s papers are of this type. From these, large diameter and/or high speed blowers are needed to generate high pressure increase and only small gaps can be tolerated between catalyst basket and blower, to minimize internal back flow. 

The basic problem of design was solved mathematically before any reliable kinetic model was available. As mentioned at start, the existence of solutions—that is, the integration method for reactor performance calculation—gave the first motivation to generate better experimental kinetic results and the models derived from them. 

The success of designing industrial reactors greatly depends on accurate and reliable laboratory data. These data are derived from the... 

The RSST can rapidly and safely determine the potential for runaway reactions. It also measures the temperature rates and, in the case of gassy reactions, pressure increases to allow reliable determinations of the energy and gas release rates. This information is combined with analytical tools to evaluate reactor vent size requirements. This is extremely useful when screening a large number of different chemicals and processes. 

Human reliability [lata NJUREG/CR-1278 was supplemented by judgment of system analysts and plant personnel. Human error probabilities were developed from NUREG/CR-12 8, human action time windows from system analysis and some recovery limes from analysis of plant specific experience. Data sources were WASH-1400 HEPs,Fullwood and Gilbert assessment ot I S power reactor Bxp., NUREG/ CR -127K. and selected acro ptice li.it.j... 

Gertman, D. I. et al., Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR), 1990. 

Fullwood, R. et al., 1977, Application of the Bayes Equation to Predicting Reactor System Reliability, Nucl. Technol. 34 p 341, August. 

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