Just a little food for thought...Last time I analyzed the 10CFR61 data for FCS, I came up with a weighted average alpha energy of about 5.5MeV. That's right about the energy of most of the Pu-238 alphas. Not as good a choice as Pu-239 due to the betas and multiple alpha energies, but it is still better than Th-230.
I've also noticed that most of the throium sources I've had have more than just Th-230 on them -- muddying the results further. For that matter, an old Pu-239 source will have Am-241 on it from the Pu-241 that is also there. A little past experimentation with an alpha spectrometer was quite educational. One good thing about most alpha detectors is a fairly flat energy response curve over the energy range we most care about. However, I have noted a fall-off in efficiency as you get down to the Th-230 alpha energy (4.7 MeV), particularly with plastic scintillators, that results in some over-reporting of alpha results and needless longer count times. At least it is conservative. My $0.02 on this. David Brehm Fort Calhoun Nuclear Station Supervisor - Radiological Equipment & Dosimetry Office: 402.533.7582 Cellular: 402.214.0107 Pager: 402.561.3310 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of GOWDY, GREGORY M Sent: Thursday, October 28, 2010 4:38 PM To: [email protected] Subject: Powernet: RE: Quick benchmarking - Alpha Calibration Sources Summer uses Am-241 also. There was an article in Radioactivity and Radiochemistry from the 90's that talked about talked about using appropriate energy alphas for various uses - Pu-238 and -239, and Am-241 for power plants and DOE applications and Th-230 and -232 for environmental labs. You may want to look this reference up to check out the specifics. Greg Gowdy, PhD, CHP Sr. Staff Health Physicist V. C. Summer Nuclear Station Jenkinsville, SC 29065 (803)-345-4426 (work) (803)-873-1561 (cell) -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Barber, Jerry Sent: Wednesday, October 27, 2010 8:23 PM To: [email protected] Subject: Powernet: RE: Quick benchmarking - Alpha Calibration Sources Robinson uses Am-241 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of BREHM, DAVID M Sent: Tuesday, October 26, 2010 5:17 PM To: [email protected] Subject: Powernet: RE: Quick benchmarking - Alpha Calibration Sources Fort Calhoun Station currently uses Thorium for calibration and response testing gross alpha/beta counters. I am working towards using Am-241 or Pu-239 for alpha calibrations as their energy is much closer to what alpha we have. We already use the Am or Pu source for setting discriminator voltages as the Th betas & gammas make it a less optimal choice. David Brehm Supervisor - Radiological Equipment Fort Calhoun Station 402-533-7582 ________________________________ From: [email protected] [[email protected]] On Behalf Of Kinmark, Michael L. [[email protected]] Sent: Tuesday, October 26, 2010 1:29 PM To: [email protected] Subject: Powernet: Quick benchmarking - Alpha Calibration Sources Columbia Generating Station has the following question: What calibration source do you use for Alpha portable instrument calibrations? Pu239, Am241, or other? Thank you in advance. Respectfully, Michael Kinmark HP Staff Advisor III Radiological Support Columbia Generating Station 509-377-2091 This e-mail contains Omaha Public Power District's confidential and proprietary information and is for use only by the intended recipient. Unless explicitly stated otherwise, this e-mail is not a contract offer, amendment, nor acceptance. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited. ----------------------------------- 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] ----------------------------------- 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] This e-mail contains Omaha Public Power District's confidential and proprietary information and is for use only by the intended recipient. Unless explicitly stated otherwise, this e-mail is not a contract offer, amendment, nor acceptance. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited. ----------------------------------- 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]
