Integral fast reactor process

A more recently developed pyrometaHurgical process is that of the proposed integral fast reactor, which would use metallic fuel (U—Pu—Zr alloy) and a molten salt electrorefiner as follows ... 

IFR [Integral Fast Reactor] A pyrochemical process for processing the fuel from a fast nuclear reactor. The uranium metal fuel is dissolved in a fused melt of lithium and potassium chlorides and... 

Uranium is among the major elements in most fuel cycles and the effective separation of actinides from lanthanides is highly desirable mainly because of the neutron poisoning properties of the fission products. Electroseparation processes are investigated widely in molten chlorides and fluorides. For example, U separation by electrolysis on a solid inert cathode is used within the integral fast reactor (IFR) concept [1]. It is the main goal of this work to extend knowledge about the possibilities of uranium separation from molten fluoride systems. 

IFR [Integral Fast Reactor] A pyrochemical process for processing the fuel from a fast nuclear reactor. The uranium metal fuel is dissolved in a fused melt of lithium and potassium chlorides and electrolyzed. The uranium deposits on the solid cathode. The transuranic elements and fission products remain in the salt and are incorporated in a zeolite matrix, which is hot-pressed into a ceramic composite waste. Developed by the Argonne National Laboratory from 1963. See also PYRO-A and PYRO-B. 

When one is dealing with localized corrosion processes, the tendency is experimentally to determine or model whether a particular process can occur in a specific environment i.e., to determine the susceptibility. Such procedures are invaluable in materials selection, and the use of electrochemical methods is an integral part of these efforts. However, in some environments it is injudicious to assume that localized corrosion will not occur. One example would be SCC in nuclear reactor heat exchangers and other components. In other applications, the need to minimize materials costs leads to the selection of materials for which there is no guarantee of immunity to localized corrosion. For such applications there is a strong need for models that will predict how fast such processes will propagate once they are initiated and what kind and extent of damage will accumulate. 

The JAERI s integrated program of data acquisition and analysis for fast reactor physics consists of several sub-programs which are evaluation of nuclear data, processing of group constants, development and improvement Of computing codes, e qieriment and analysis, and adjustment of group constants. The Japanese nuclear data committee is responsible for evaluation of nuclear data. 

PRISM is often coupled with an integrated, commercial-scale, recycling facility capable of processing LWR and fast reactor UNF and fabricating PRISM TRU fuel for the co-located PRISM power blocks. 

The equipment required to develop this type of sensor is very simple and resembles closely that used to implement ordinary liquid-solid separations in FI manifolds. The only difference lies in the replacement of the packed reactor located in the transport-reaction zone with a packed (usually photometric or fluorimetric) flow-cell accommodated in the detector. Whether the packing material is inert or active, it should meet the following requirements (a) its particle diameter should be large enough (< 80-100 fim) to avoid overpressure (b) it should be made of a material compatible with the nature of the integrated detection system e.g. almost transparent for absorbance measurements) and, (c) the retention/elution process should be fast enough to avoid kinetic problems. 

In their pioneering work, Jensen et al. demonstrated that photochemical transformation can be carried out in a microfabricated reactor [37]. The photomicroreactor had a single serpentine-shaped microchannel (having a width of 500 pm and a depth of 250 or 500 pm, and etched on a silicon chip) covered by a transparent window (Pyrex or quartz) (Scheme 4.25). A miniature UV light source and an online UV analysis probe were integrated to the device. Jensen et al. studied the radical photopinacolization of benzophenone in isopropanol. Substantial conversion of benzophenone was observed for a 0.5 M benzophenone solution in this microflow system. Such a high concentration of benzophenone would present a challenge in macroscale reactors. This microreaction device provided an opportunity for fast process optimization by online analysis of the reaction mixture. 

Now we can really see why the CSTR operated at steady state is so different from the transient batch reactor. If the inlet feed flow rates and concentrations are fixed and set to be equal in sum to the outlet flow rate, then, because the volume of the reactor is constant, the concentrations at the exit are completely defined for fixed kinetic parameters. Or, in other words, if we need to evaluate kab and kd, we simply need to vary the flow rates and to collect the corresponding concentrations in order to fit the data to these equations to obtain their magnitudes. We do not need to do any integration in order to obtain the result. Significantly, we do not need to have fast analysis of the exit concentrations, even if the kinetics are very fast. We set up the reactor flows, let the system come to steady state, and then take as many measurements as we need of the steady-state concentration. Then we set up a new set of flows and repeat the process. We do this for as many points as necessary in order to obtain a statistically valid set of rate parameters. This is why the steady-state flow reactor is considered to be the best experimental reactor type to be used for gathering chemical kinetics. 

Natural gas steam reforming process is an ideal candidate for hydrogen selective membrane integration tanks to its high reaction endothermicity and the fast kinetics leading to equilibrium condition inside traditional reactors. 

Fig. 4.14. A special type of integral reactor (pseudo-integral reactor) is one constructed with taps at various distances along the length so that samples may be removed and the actual concentration profile measured. A disadvantage of integral reactors is that the balance equations are a system of coupled differential equations. The measured conversion often is due to a complex interaction of transport and reaction processes. For quick, empirical, and pragmatic process development, the integral reactor may be well suited, especially now that fast digital computers and effective integration algorithms facilitate parameterization.

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