Light water reactors - 359 in operation in the world, of which 104 are in the US.
http://www.iaea.org/NuclearPower/WCR/LWR/
The USA has 104 nuclear power reactors - 69 pressurized water reactors (PWRs) with combined capacity of about 67 GWe and 35 boiling water reactors (BWRs) with combined capacity of about 34 GWe.
http://www.world-nuclear.org/info/inf41.html
France has 58 nuclear reactors operated by Electricite de France (EdF), with total capacity of over 63 GWe, supplying 421 billion kWh per year of electricity (net), 78% of the total generated there in 2011.
http://www.world-nuclear.org/info/inf40.html
Russia has 33 reactors: 1 FBR, 11 RBMKs, 17 VVERs, and 4 small graphite moderated reactors.
http://www.world-nuclear.org/info/inf45.html
The Republic of Korea (S. Korea) has 4 CANDUs and 17 PWRs.
http://www.world-nuclear.org/info/inf81.html
Germany has 17 operating nuclear power reactors. Six units are boiling water reactors (BWR), 11 are pressurised water reactors (PWR). All were built by Siemens-KWU.
http://www.world-nuclear.org/info/inf43.html
The UK has a fleet of gas-cooled (CO2) reactors, 3 Magnox and 14 AGRs. There is one PWR in the UK.
http://www.world-nuclear.org/info/inf84.html
Sweden has 10 LWRs - 7 BWRs (2 BWR units were shutdown, one in 1999 and the other in 2005) and 3 PWRs
http://www.world-nuclear.org/info/inf42.html
Spain has 8 LWRs - 2 BWRs and 6 PWRs
http://www.world-nuclear.org/info/inf85.html
Switzerland has 5 LWRs - 2 BWRs and 3 PWRs.
http://www.world-nuclear.org/info/inf86.html
There are a handful of liquid metal (fast) reactors.
More general information - http://www.world-nuclear.org/info/
http://www.world-nuclear.org/info/reactors.html
Fuel is spent when the fissile inventory is depleted and fission products have accumulated to the point where is it not economical to continue operation, or the fuel has reached it's technical (licensed) limits, and the fuel is discharged.