Shutdown matrix

The FCC process is very complex and many scenarios can upset operations. If the upset condition is not corrected or controlled, each scenario could lead to a reversal. Table 8-1 contains a cause/effect shutdown matrix indicating scenarios in which a shutdown (reversal) could take place. In most cases, a unit shutdown is not necessary if adequate warning (low alarms before low/low shutdowns) is provided. The operating staff must be trained to respond to these warnings. 

Listed across the top of the matrix are the various shutdown valves in the facility. A mark in each box indicates the function performed by each device to assure that it protects the process component. By comparing the functions performed by each device to the mechanical flowsheet, it is possible for an auditor to quickly ensure that the process component is indeed isolated. 

All measurements were performed with the program GIRAF and with the previous ones without shutdown of the instrument at the same analytical conditions (according to Perkin-Elmer cookbook ) by the same analyst with the same reference materials applied as calibration and test solutions. The matrix modifier for lead determination by graphite furnace analysis was used separately from the reference materials, i.e. was not mixed with them. The matrix modifier for sodium determination by flame atomic emission analysis was introduced in all corresponding solutions (the blank and the reference materials for the calibration and test). Three replicates of all measurements were made. 

The reserve shutdown material consists of 40 weight percent natural boron in B C granules dispersed in a graphite matrix and formed into pellets. The... 

Fisher, P. A., Lin, L., McConneU, M., Greenleaf, A., Lee, J.-M., and Smith, D. E. (1989). Heat shock-induced appearance of RNA polymerase II in karyoskeletal protein-enriched (nuclear matrix ) fractions correlates with transcriptional shutdown in Drosophila melanogaster. J. Biol. Chem. 264, 3464-3469,... 

Due to its neutron-absorbing efficiency, boron carbide is attractive as a neutron absorber material, and is used both in powdered and solid forms to control the rate of fission in nuclear reactors (Figure 4.19b)[530j. B4C mixed with other materials, such as aluminum metal or polyethylene plastic, is applied to protect it against oxidation in the reactor environment. AI-B4C metal-matrix composite plates (e.g., Boral, Bortec) have wide applications as isolators in spent fuel element racks, in the inner sections of reactor shields as shutdown control rods and neutron curtains, as shutters for thermal columns, and as shipping containers. 

Experiments show the non wetting behavior (Fig. 3) of the fluoride salts of interest, that molten salts will not penetrate small cracks in the graphite and that the molten salt will not contact the fuel matrix (Briggs 1963 ORNL 1964 Fontana 1970). In a classical molten salt reactor where the uranium and fission products are dissolved in the fuel salt, the fuel salt is dumped to storage tanks during shutdown. 

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