Khusab-2 is a 50MW plutonium production reactor. Construction began around 2001 and open source satellite imagery showed signs that the reactor may have become operational in late 2009.[1]

While Khushab-1 is moderated by heavy water and cooled by light water, Khushab-2 may use heavy water as both the moderator and coolant.[2] If true, this would enable plutonium production utilizing less power. Assuming Khushab-2 will have production capabilities similar to Khushab-1, as fuel from Khushab-2 becomes available for reprocessing, Pakistan's annual production of weapons-grade plutonium could double.[3] The facility is not under IAEA safeguards.

Sources:
[1] Paul Brannan, "Steam Emitted From Second Khushab Reactor Cooling Towers; Pakistan May Be Operating Second Reactor," Institute for Science and International Security, 24 March 2010, www.isis-online.org.
[2] Global Fissile Material Report 2010, Chapter 10, International Panel on Fissile Materials, December 2010, www.fissilematerials.org.
[3] Global Fissile Material Report 2010, Chapter 10, International Panel on Fissile Materials, December 2010, www.fissilematerials.org.