Initial critical inventories

Fig. 14-3. Initial critical inventories of in two-region, homogeneous, molten fluoride-salt reactors. External fuel v6lume, 339 ft .

Uranium-233 is a superior fuel for use in molten fluoride-salt reactors in almost every respect. The fission cross section in the intermediate range of neutron energies is greater than the fission cross sections of U and Pu239 Thus initial critical inventories are less, and less additional fuel is required to override poisons. Also, the parasitic cross section is substantially less, and fewer neutrons are lost to radiative capture. Further, the radiative captures result in the immediate formation of a fertile iso-... 

Initial states. Critical concentration, mass, inventory, and regeneration ratio. The results of calculations of a plutonium-fueled reactor having a core diameter of 8 ft and no thorium in the fuel salt are described below. The critical concentration was 0.013 mole % PuFs, which is an order of magnitude smaller than the solubility limits in the fluoride salts of interest. The critical mass was 13.7 kg and the critical inventory in a 600-Mw system (339 ft of external fuel volume) was only 31.2 kg. 

The ability of short-lived radioisotopes to function as chronometers for the early solar system is critically dependent on there having been an initially uniform distribution of the radioactivity throughout the nebula, or at least in those regions from which meteoritic components are derived. Only in this circumstance can differences in initial abundances of a radionuclide compared to a stable counterpart, as inferred by the excesses of the respective daughter isotope, be interpreted as due to radioactive decay from the initial inventory. The homogeneity of the distribution of radionuclides in the solar nebula depends, in turn, on the processes that created those isotopes some time before the formation of early solar system materials. For the longer-lived isotopes listed in Table 1 (e.g., Hf, 129 92, ... 

Since the conditions in general are difficult to verify, Thowsen discusses special cases under which the (y,p) policy is optimal for the problem considered. For instance, under a linear expected demand curve, linear stockout costs, convex holding costs, and a demand distribution that is a PF2 distribution, the iViP) policy is optimal. Furthermore, if excess demand is backlogged, the demand curve is concave and the revenue is collected a fixed number of periods after the time orders are placed, then no assumptions are needed on the cost and demand distribution for optimality of the critical number policy, and for this case the decision on price and quantity decisions can be made separately. Thowsen also shows that if negative demand is disallowed, the optimal price will be a decreasing function of increasing initial inventory. 

With growing concern of environment and sustainability, Imerys has taken an initiative to evaluate the sustainability aspects of the calcium carbonate mineral. lifecycle inventory (LCI) is a key part of the International Environmental Management System standards 14044 2006. This tool is used by companies in the plastics supply chain to understand the environmental impact of raw materials critical for plastics production. LCI analysis of treated ground calcium carbonate compared to base resins was carried out since treated GCC is used to replace some of the resin volume in plastics production. The production of treated GCC was found to have a lower impact on the environment than the production of various resin systems, including PVC, PE, and PP. Raw material and energy use inputs were included in the study, as were environmental emissions to land, air, and water [11]. 

An accurate chemical inventory is the foundation for your overall chemical management initiatives. It will ensure that there are no cracks in your foundation, which should be built on an understanding of what chemicals you have on site and where they re located. Understanding the entry points for chenticals is also critical. Without it, aU downstream processes for hazard communication, regulatory reporting, and even internal sustainability initiatives will suffer. 

The honeycomb critical assembly is a universal split table machine containing a 1.83-m ( ft>cubical matrix of 76-mm (3 in.)-square aluminum tub It is deagned to serve as a flexible system for initial mbckup studies for basic critical parameter investigations. Fuel inventory consists of various Assile species such as 330 kg of O.OS-mm-thick U(93) foils with widths and lengths appropriate to the aluminum matrix tubes. Control and safety rods utilize sections of the core or reflector materials for their flmction and major disassembly is provided by the movable section of the table. Honeycomb is presently stacked with a UOrMo (core). Be (reflector) mockup of a space powa reactor. 

It is well known that repositories studied so far have been for power reactor fuel with initial enrichment of 4% or less, being about 1% the remnant enrichment in the spent fuel inventory. Repeating these studies for research reactor fuel, including the environmental impact assessment, would be enormously expensive. Besides, criticality considerations and the susceptibility of the materials to degradation lead to the conclusion that direct disposal of RRSF cannot be considered a viable option. 

Pressure vessel orientation should avoid pointing vessel ends toward critical equipment or high inventory locations. The ends of long horizontal pressure vessels are vulnerable to initial failure in a fire exposure and therefore they may project off like a projectile from a canon. It is therefore best to orientate the ends of these vessels so they will not project the ends to other critical facilities or areas that could escalate the incident. 

It would be of Interest to have the views of the Author in particular on the plans for the Nova Scotia plants. It would be particularly interesting to know whether any expansion of the capacity of these plants is foreseen and how quickly this expansion could be achieved after the decision is made. It seems to me that the future cost of heavy water may become critically dependent on the capacity of plant which will have to be Installed and the degree of utilization that such plant will achieve after the initial inventories of reactors has been met. 

Benefits of CPFR Until now, most CPFR initiatives focused on reducing variable costs, such as decreasing inventory levels. However, there are further benefits to be gained for companies that integrate CPFR into their standard operational procedure and scale to critical mass (see Figure 4.11). 

Insulation Applications Resin electrical properties become critical for insulation apphcations (the compound in direct contact with the metal conductor). Resins need to be specially manufacmred in order to minimize residual initiators, catalysts, and contaminants, which can negatively impact electrical properties. One of the ways this is accomplished is by carrying out the suspension resin polymerization process in deionized water and minimizing residual surfactant. Mass resins have found use in this application in the past due to the fact they do not require electrically deleterious surfactants agents in their manufacture. In order to minimize raw material inventory, many wire and cable manufacmrers who compound their own PVC formulations attempt to use the same resin for both jacket and insulation compounds. Because of this, resins with a T-value around 70 also predominate in insulation applications. 

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