[ RadSafe ] Reporter's question about lower limits of detection
mattwald at nytimes.com
Fri Aug 5 10:30:41 CDT 2011
I have been a "lurker" on this list for a couple of years, and I write intermittently about nuclear power.
Could someone who is expert on this subject please help me with a radiation measurement question?
What is the lower limit of detection for strontium-90 in fish ?
The Vermont Department of Health samples fish from the Connecticut River. It recently reported finding strontium-90 in some samples, slightly above what it said was the lower limit of detection, 47 pCi/kg. See: http://healthvermont.gov/enviro/rad/yankee/tritium.aspx
A website called Vermont Digger, http://vtdigger.org/2011/08/02/vermont-yankee-4/, reported on the result. But Vermont Digger also says that New York measured 8 pCi/kg.
The underlying issue is whether the strontium came from the Vermont Yankee reactor, in Vernon, near the Massachusetts border, which had a leak from an underground pipe, or whether it is from fallout or some other source. But I have another question.
What is the lower limit of detection? 8 picocuries per kg? 47? Some other number? And what determines the lower limit?
I would appreciate any explanation.
--- Matt Wald
Matthew L. Wald
The New York Times
1627 Eye St NW, Suite 700
Washington, DC 20006
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