The first signs of a leak in Hanford double-shell tank AY-102 were detected in October 2011, a full year before the Department of Energy and Washington River Protection Solutions announced the leak officially.
Oct. 9: Leak detection equipment (ENRAF) senses liquid in AY-102 annulus and goes into alarm.
Oct. 10: WRPS employee Mike Geffre and a colleague check the ENRAF to see if it is malfunctioning. They see waste residue on a part (the plummet) of the ENRAF that monitors liquid in the tank annulus. A Geiger counter reading through leaded glass shows the ENRAF plummet is emitting radiation.
Geffre alerts his WRPS managers that he believes the tank has a leak based on his visual inspection and radiation found. Managers respond by saying the ENRAF must have malfunctioned and that rainwater, not nuclear waste, must have seeped into the annulus space.
Oct. 12: Geffre checks the AY-102 ENRAF again and confirms it is working properly. Notes plummet is wet in a report. He also take a photo.
Gary Tardiff, an engineer working at the AY tank farm, recommends that a camera be deployed into the AY-102 annulus to scan for signs of water intrusion.
Oct. 24: Geffre is asked to flush the plummet on the AY-102 ENRAF that went into alarm on the 9th. Before the flush, a Geiger counter reading shows the plummet emitting 5 millirem of radiation; after the flush, the reading drops to 1.5 mrem.
Oct. 26: A spike in radiation levels is recorded by a continuous air monitor (CAM) on AY-102, possibly because the flushing of the plummet on Oct. 24 stirred up more contaminated particles into air in the annulus.
Oct. 27: WRPS managers task Geffre with re-setting the ENRAF on AY-102 into a less sensitive state. Geffre conducts the re-set under protest. The ENRAF's new setting results in it ignoring the leak it detected on Oct. 9.
March 10: ENRAF plummet is found to be stuck to the bottom of the AY-102 annulus in the exact spot where the ENRAF detected a leak in 2011.
Apr. 16: Video inspection request made on Oct. 12 is officially cancelled. "No inspection needed" is marked as the reason for the change.
May 24: Wire that suspends ENRAF plummet into AY-102 annulus breaks. Wire and reel pieces that are retrieved are found to be reading a radioactive reading of 20,000 dpm/100cm2.
June 4: A bullet camera is deployed into the AY-102 annulus to locate the plummet stuck on the bottom. Employees say the video from the camera showed images of what looked like nuclear waste.
Aug. 1: WRPS begins a regularly scheduled detailed video inspection of the AY-102 annulus.
Aug. 10: Samples of waste material retrieved from the AY-102 annulus floor are sent to the 222-S lab at Hanford for testing.
Aug. 13: Preliminary test results show the material to contain four radioactive elements that match the type of elements contained in AY-102.
Sept. 7: At a meeting of the Hanford Advisory Board, DOE tank farm official Tom Fletcher says the source of the waste in the AY-102 annulus remains undetermined. Board members said they left thinking the situation with the tank was not critical.
Oct. 22: The Dept. of Energy's Office of River Protection and WRPS confirm that AY-102 is leaking radioactive waste into its annulus.