It does not take much effort to gather a few EPDs that are used at your facility and set them in radiation fields of a 5, 10, 25, 50, 75, or 80 mR/h for ten to fifteen minutes and record the maximum exposure rates stored on the devices for each environment. OR, if you are really into data gathering (which I am), record each and every rate displayed and see the entire distribution of rate variations (A Model 89 with a viewing port is great for this).
This will provide your own assessment of sampling variabilities of these devices at reasonably important exposure rates. There are differences in the sampling algorithms between the major EPDs. One may provide longer sampling, while another may be reasonably quicker in response to changing fields. They both have their advantages and disadvantages, but it is not a ton of effort to understand what your device does. Mike Lantz, CHP On Jun 18, 2012, at 12:17 PM, Geyster, John J wrote: > What make and model was the testing done on? > Not that it makes that much of a difference as they all use a similar method. > > From: [email protected] [mailto:[email protected]] On Behalf Of > [email protected] > Sent: Thursday, June 14, 2012 6:18 PM > To: [email protected] > Subject: Powernet: RE: Dose rate threshold > > Yes. since the primary function of most electronic dosimeters is to > integrate dose, an algorithm is used to approximate a dose rate by dividing > incurred dose over a short sample time (generally around three seconds). > While this works fairly well in moderate to high dose rate fields, in low > dose rate situations the short sample time coupled with the random nature of > decay introduces significant low background counting statistical errors which > result in erroneous (false) alarms. We did extensive empirical testing of > this and found that dose rate setpoints < 50 mR/hr are of little to no value > due to high false alarm rates. To ensure low to no false alarms, minimum > setpoint values for rate alarms at or above 75 mR/hr work very well. > > > ********************************************************************** > Seth J. Kanter, CHP, RRPT > Sr. Health Physicist > Palo Verde Nuclear Generating Station > Mail Sta. 7397 > 5801 S. Wintersburg Rd. > Tonopah, AZ 85354 > Phone (623) 393-3130 > Fax (623) 393-1853 > Unless otherwise noted, all opinions are my own > Liviu Librescu > ********************************************************************** > > > > From: [email protected] [mailto:[email protected]] On Behalf Of > THOMPSON, THEODORE W > Sent: Thursday, May 31, 2012 8:55 AM > To: [email protected] > Subject: Powernet: Dose rate threshold > > I would like to know if anyone has established or proceduralized a minimum > threshold to set the dose rate on the electronic dosimeters at in low dose > rate areas (i.e. 5 mrem/hour general area). If not, are you using INPOs > guidance of 150% for dose rates up to 100 mrem/hr general area and 125% above > 100 mrem/hr general area. > > > > Ted Thompson > Health Physicist > Ft. Calhoun Nuclear Station > OPPD > Email: [email protected] > Phone: 402-533-7152 > > 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, > or 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. > --- NOTICE --- > > This message is for the designated recipient only and may contain > confidential, privileged or proprietary information. If you have received it > in error, please notify the sender immediately and delete the original and > any copy or printout. Unintended recipients are prohibited from making any > other use of this e-mail. Although we have taken reasonable precautions to > ensure no viruses are present in this e-mail, we accept no liability for any > loss or damage arising from the use of this e-mail or attachments, or for any > delay or errors or omissions in the contents which result from e-mail > transmission.
