The inventory required for operations

You can certainly determine the current inventory level of the enterprise, at the very least of the last balance, and get riled up about it again. 

How do you actually know which level would be justifiable  

Schmalenbach once said that benchmarking means comparing sloppiness to sloppiness.  

Yet it is very simple to determine the actual inventory level required. You only have to truly want to know. 

We approach it as an analysis What does the inventory of a stored part or product consist of (Fig. 51)  

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If you calculate the inventory value and make the same calculation for all other stored parts including products and add up the inventory values determined for all reference numbers, you have the inventory required for operations, as long as you keep your parameters for buffer time and lot size calculations. 

Made-to-order manufacturers should calculate the consignment parts needed to determine the inventory required for operations in due time. 

Then compare your actual inventory with the inventory you calculated as being required for operations. You now see where you need to take action. The quotient of the actual inventory and the inventory required for operations is an extremely important management figure which must be monitored constantly. Experience shows that the figure exceeds 2.0 on the first calculation. This means that the actual inventory is at least twice as high as the inventory required for operations on the basis of your parameters. 

A skills inventory that lists each piece of equipment or operation and the skills required for operating or maintaining that equipment can indicate the need for training to fill voids in available sldlls (Peele and Chapman 1989). 

Also, there is a requirement that the emergency feedwater system shall have sufficient inventory to permit operation at hot shutdown for at least 4 hours, followed by a cooldown to the conditions permitting operation of the RHR system. The inventory needed for cooldown, shall be based on the longest cooldown required with either onsite or offsite power available with an assumed single failure. 

This average inventory corresponds exactly to the inventory of this reference number required for operations once you have determined your parameters, such as e.g. inventory interest. 

It is derived from the quotient of actual inventory level and the inventory level required for operations ... 

Operating Expenses The money required for a system to convert inventory into throughput. 

May be used in conjunction with chlorination or other nonoxidizing biocides, but has been found to be effective when used as the sole means for biological control. This provides a simple treatment approach based on chemical inventory requirements and operator training. 

Safety. A large inventory of radioactive fission products is present in any reactor fuel where the reactor has been operated for times on the order of months. In steady state, radioactive decay heat amounts to about 5% of fission heat, and continues after a reactor is shut down. If cooling is not provided, decay heat can melt fuel rods, causing release of the contents. Protection against a loss-of-coolant accident (LOCA), eg, a primary coolant pipe break, is required. Power reactors have an emergency core cooling system (ECCS) that comes into play upon initiation of a LOCA. 

The demand for uranium ia the commercial sector is primarily determined by the consumption and inventory requirements of nuclear power reactors. In March 1997, there were 433 nuclear power plants operating worldwide with a combined capacity of about 345 GWe (net gigawatts electric)... 

The design of inherently safe process plant is discussed by Kletz in a booklet published by the Institution of Chemical Engineers, Kletz (1984) and Keltz and Cheaper (1998). He makes the telling point that what you do not have cannot leak out so cannot catch fire, explode or poison anyone. Which is a plea to keep the inventory of dangerous material to the absolute minimum required for the operation of the process. 

Batch operation requires a larger inventory than the corresponding continuous reactor. Thus, there may be a safety incentive to change from batch to continuous operation. Alternatively, the batch operation can be changed to semibatch in which one (or more) of the reactants is added over a period. The advantage of semibatch operation is that the feed can be switched off in the event of a temperature (or pressure) excursion. This minimizes the chemical energy stored up for a subsequent exotherm. 

The planner can indude the stock costs in addition to the other costs, but as a consequence delay costs are balanced with stock costs. Here this effect is not wanted at first high demand satisfaction is required. Keeping this to the maximum level, stock costs are lowered around this optimum. The trade off between production for future demands and inventory costs can be maximized by the so called shift operator. 

For ESD isolation valves (i.e., EIVs) a fail safe mode is normally defined as fail closed in order to prevent the continued flow of fuel to the incident. Blowdown or depressurization valves would be specified as fail open to allow inventories to be disposed of during an incident. Special circumstances may require the use of a foil steady valve for operational or performance reasons. These applications are usually at isolation valves at components, i.e., individual vessels, pumps, etc., where a backup EIV is provided at the battery limits that is specified as fail closed. The fail safe mode can be defined by the action that is taken when the ESD system is activated. Since the function of the ESD system is to place the facility in its safest mode, by definition the ESD activation mode is the foil safe mode. 

These same notions can be extended to an entire plant in which several unit operations are connected together. The HDA process for hydrodealkylation of toluene to form benzene is a good example of where an eigenstructure can be found that provides a more easily and simply controlled plant. See Fig. 8.15. Assuming that the toluene feed rate to the unit is fixed, this plant has 22 valves that must be set. There are 11 inventory loops (levels and pressures), so they require 11 valves. One possible conventional control structure is shown in Fig. 8.15. 

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