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

03 February 2012

Answer to Question #1471 Submitted to "Ask the Experts"

Category: Environmental and Background Radiation — Measurements and Reporting

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

I am studying soil and groundwater contamination by thorium. Lab results for thorium concentration are expressed in ppb and norms for drinking water are in Bq/L. How can I convert ppb in Bq/L for thorium and for radionuclides in general?

An easy-to-remember conversion is the fact that for thorium 1 picocurie per gram (pCi/g) = 10 ppm. As such:

1000 pCi/L = 10 ppm
1 pCi/L = 0.01 ppm
1 pCi/L = 10 ppb (where 1 billion = 1000 million)
Given that 1 pCi = 0.037 Bq (that is, 1 Bq = 27 pCi)
1 Bq/L = 270 ppb of thorium

You can perform the same sort of calculations for natural uranium given the fact that 1 pCi/g = 3 ppm. Forgive me, but it is probably best to avoid answering the second part of your question. Performing the calculations for "radionuclides [elements?] in general" is not difficult, but it is best done by someone who has had some training and experience. A complicating issue is the fact that a given element, such as thorium, can consist of multiple nuclides (²³²Th, ²³⁰Th, etc.).

Paul Frame, CHP, PhD

Answer posted on 14 December 2001. 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.