Other studies of the nuclear power sector find that indirect labour is approximately equal to direct labour (see IAEA, 2009 for Korea), i.e. this method identifies about 75% of the indirect labour with 25% of the indirect labour supplying the needs of the nuclear construction supply chain, e.g. in supplying materials to the machinery manufacturing industry (NAICS 333). For 50 years of operation, annually there are approximately 600 administrative, operation and maintenance, and permanently contracted staff, or about direct 30 000 labour-years during operation. To understand how these jobs are distributed locally, regionally and nationally, Table 9.3 breaks down the 15 largest categories of spending during the operation of an NPP.