Re: How to define ACCEPTABLE detection capability ?

["Leon E Brown" <lebrown@CMSENERGY.COM>]

ChiChang Liu,


You asked "Could anyone tell me the reason that the LLD levels on TABLE 3 of REG. GUIDE 4.8 are "ACCEPTABLE" minimum criteria for objectives for instrumentation and analytical procedure selection for environmental samples ? Dose these levels derive from dose limits ?"


First of all, the radiological portion of the environmental monitoring program contained in RG 4.8 was superseded by the NRC's Branch Technical Position (BTP) on environmental monitoring issued in March, 1978.  Revision 1 to the BTP was issued as an enclosure to Generic Letter 79-65 in November 1979 which, I believe is the most current version of the NRC's guidance on radiological environmental monitoring.


As to answering your question, I believe the answer is contained in GL 79-65.  It states "The specified detection capabilities are state-of-the-art for routine environmental measurements in industrial laboratories."  Therefore, it appears that the LLD levels are based on nothing more than minimum detection levels of instrumentation and analytical methods that the NRC would reasonably expect its licensees to use for analyzing environmental samples.  Of course, even in 1979, there were instrumentation and analytical methods capable of achieving lower LLDs but I assume that the NRC viewed the additional costs required to achieve the lower LLDs as unreasonable.


Leon E. Brown

Staff Consultant

Big Rock Point Restoration Project

(231) 547-8419

lebrown@cmsenergy.com