"Nuclear Implosion, The Rise and Fall of the Washington Public Power Supply System" by Professor Daniel Pope of the University of Oregon admirably explains the background of this incredible anomaly in the outage world.
Of the 35 BWRs in the US, four are Model 5 BWRs. Columbia, Nine Mile 2, Lasalle 1&2.
The current light water world record run is held by Lasalle Unit 1...739 days.