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Reference, Questions and Help => Nuke Q&A => Instrument Q&A => Topic started by: Irradiated1 on Apr 20, 2010, 09:21

Title: Any old timers familiar with a Packard 3385 Liquid Scintillation Counter?
Post by: Irradiated1 on Apr 20, 2010, 09:21

I came across a Packard 3385 Liquid Scintillation counter built in 1974. I'm trying to figure out if the source was removed from this beast of a machine. A researcher has a vague recollection of the source being removed but the source plaque remains in tact. Typically when the source is removed the vendor removes the plaque. I'm trying to identify where the Ra-226 is located in this model. I've removed some side panels but no dice. The sample chamber is located in the base of the machine so I'm guessing the lead, PMT's are just below. Can anyone familiar with this machine let me know where the source might be located? I believe it to be under the sample loading tray. I need to at least get a visual confirmation that it is/or is not present to get a vendor out to remove it.

Title: Re: Any old timers familiar with a Packard 3385 Liquid Scintillation Counter?
Post by: Scottsr3 on Apr 22, 2010, 02:40

My co-worker used to work on these. He said there is an L shaped tube in the freezer that carries the barbell shaped source to a position between the detectors. Hope this helps.

Title: Re: Any old timers familiar with a Packard 3385 Liquid Scintillation Counter?
Post by: Mike_Koehler on Apr 22, 2010, 06:04

The 3385 had two pellets - an RA226 and an Americium 231. They were placed into an "L" tube and moved into and out of the counting chamber with an air pump. If you need a cutaway view please PM me and I will try to send it to you.
If you place a squeezeball onto the tube exiting the rear of the freezer and squeeze the ball, you should be able to hear the pellets and the 2 stainless steel balls (and spacer) sliding into and out of the counting chamber. You can always survey the tube and top of the counting chamber with a survey meter to see if you have any radioactivity.

The sample changer is hinged to the rear of the pig assembly, so if you lift up on the front of the table, it will snap clear of a small clip and pivot back out of the way. You can then reach down the front inside wall of the freezer and loosen the swaglok connector at the bottom of the elevator to remove the L tube.

Title: Re: Any old timers familiar with a Packard 3385 Liquid Scintillation Counter?
Post by: Irradiated1 on Sep 08, 2010, 07:22

Thanks Mike your instructions were a tremendous help. The sources were indeed still in place. The vendor was contacted and the sources removed for disposal.