Managing spares for improved availability

A recent survey by the U.S. Nuclear Regulatory Commission of maintenance practices at U.S. nuclear power plants confirms that spare parts availability is, to some extent, a problem at all but a few plants. Fortunately, significant improvement is possible without ballooning inventory. The vast majority of total dollar value of spare parts inventory at power generation stations, whether nuclear or fossil, is rarely used (parts or components that are used 12 or less times per year including many with a history of no use for many years). Because rarely used inventory is not effectively managed with traditional inventory management techniques, opportunities exist both to increase availability and to reduce investment. But this requires a unique statistical tool that can recommend an unbiased, economic reorder point to be used in the materials management system. Inventory Solutions Inc. (ISI) of Akron, Ohio, has developed such a tool, rarely used inventory stocking logic (RUSL), which is a user friendly decision support tool for setting spare parts reorder points. RUSL, based on statistical computations enhanced to include the most advanced techniques developed for use in aerospace and military combat-readiness, calculates the optimum stocking level to achieve the desired spare part availability at the station.