looks like they did an upgrade in 2011
found one story (404s) on wikipedia
Old supercomputers may go to universities. 20 April 2011. Knox News. Retrieved 23 May 2011.
ALERT
an article about what happened to the Kraken after decommissioning has been scrubbed.
https://www.nics.tennessee.edu/kraken-retrospective
https://www.nics.tennessee.edu/kraken/specifications
checking way back
The Kraken system has evolved through a series of deployments—from a Cray XT3 at project inception to a Cray XT4 in mid-2008, and then to a Cray XT5 in 2009. The XT5 deployment progressed in late 2009 through a planned upgrade from 4-core processors to 6-core processors. In early 2011 an unplanned but essential memory upgrade was successfully proposed and added to the 6-core-processor upgrade, and an additional 12 cabinets were added to the original 88. All of these deployments and upgrades were executed on scope, within budget and on time.
https://web.archive.org/web/20150215031655/https://www.nics.tennessee.edu/kraken-retrospective
https://web.archive.org/web/20140616050214/http://www.nics.tennessee.edu/kraken-decommission-faqs