Jerry, Sequoyah U1 had the misfortune of ejecting a thimble tube at the high pressure fitting into the instrument room. This was in 1984. The unit was at 30% power and the thimble tubes were being cleaned using a mechanical cleaning machine. The machine overstressed the fitting causing it to fail. The team noticed the water leaking around the fitting and exited the area just as the tube was ejected - no injuries or overexposures. Best effort surveys of the thimble tube found 4000 R/hour using a RO7 with a high range probe. The survey was performed using an extended probe while hiding behind a shield curtain. Sequoyah-1 is a 4 loop Westinghouse plant.
Joel Armstrong TriVis ALARA Engineer Sequoyah Dry Cask Storage Project [email protected] (423) 593-7043 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Barber, Jerry Sent: Wednesday, February 08, 2012 9:44 AM To: '[email protected]' Subject: Powernet: Expected Dose Rates from Irradiated Thimbles In preparation for removal and cut up of 10 incore thimbles that will be replaced at our Westinghouse PWR this outage, I am looking for a reference that gives expected dose rates from irradiated thimbles. Thanks, Jerry Barber Lead RC Specialist H.B. Robinson Nuclear Plant 843-857-1496 [email protected] ----------------------------------- Powernet - a service of the Health Physics Society Power Reactor Section Powernet archives at http://www.mail-archive.com/[email protected]/ Reply to: [email protected] If Questions, contact Mike Russell, CHP at [email protected] ----------------------------------- Powernet - a service of the Health Physics Society Power Reactor Section Powernet archives at http://www.mail-archive.com/[email protected]/ Reply to: [email protected] If Questions, contact Mike Russell, CHP at [email protected]
