What's New?
.	Fukushima Decontamination Report
.	CRCPD & CDC Grants for Volunteer Corps
.	America's Nuclear Future
.	February Newsletter
.	Boice Nominated President of NCRP
.	February Journal
.	February ORS
.	Schauer Given the Butterfly Award from Image Gently
.	Kase President's Report to IRPA
.	IRPA13 Accepting Posters

Upcoming Events
.	HPS Midyear - Issues in Waste Management 5-8 February 2012 Dallas, Texas
.	NRC Regulatory Information Conference NRC Regulatory Information Conference 13-15 March 2012 Rockville, Maryland
.	NCRP Annual Meeting 12-13 March 2012 Washington, DC
.	James E. Turner Memorial Symposium Call for Abstracts 18-19 April 2012 Oak Ridge Associated Universities, Pollard Auditorium, Oak Ridge, Tennessee
.	IRPA13 13-18 May 2012 Glasgow, Scotland
.	Canadian Radiation Protection Association (CRPA) Annual Meeting 27-30 May 2012 Halifax, Nova Scotia
.	ACS Undergrad Summer Schools 10 June- 20 July 2012
.	Nuclear Regulatory Commission Meeting Webcasts February 2012 Bethesda, Maryland

09 February 2012

Answer to Question #82 Submitted to "Ask the Experts"

Category: Doses and Dose Calculations — Conversion of survey meter readings to dose

The following question was answered by an expert in the appropriate field:

I have a GM counter that reads in dps for beta and I need to record my results in mrem h^-1. What is the formula?

It depends somewhat on the type of GM detector being used and possible differences in calibration. For a side-window type detector, a dose-rate conversion factor of 2000 cpm/mrad/h (open-window) has been used by our group in the past for measurement of beta dose rates from ²³⁸U. I have personally never seen the data on which this conversion was based, however it is highly consistent with observed values for GM-pancake data that has been collected since. For a pancake-type GM detector, values have been measured (at ORNL) and have ranged from about 2300 up to 4000 cpm/mrad/h with an open-window probe. The most probable response for a pancake and the selection that is most often used by our group is 2400 cpm/mrad/h and appears to be valid over a fairly broad beta energy range. Note that these conversion factors are for estimating dermal dose by beta irradiation which means that it is the dose rate at 70 um beneath the surface of the skin. Also note that the conversion assumes that count losses are negligible or have already been accounted for otherwise. Robert Coleman Oak Ridge National Laboratory

The information and material posted on this website is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Website. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.