MY NOTE: THIS PDF LINK WILL BE OF GREAT INTEREST TO THE API CONTINGENT, WHO READ THIS BOARD.
http://www.epa.gov/nrmrl/pubs/600r11037/600r11037.pdf
The following is the introduction from the pdf:
The verification test will be conducted under the U.S. Environmental Protection Agency (EPA) Environmental Technology Verification (ETV) Program. It will be performed by Battelle, which is managing the ETV Advanced Monitoring Systems (AMS) Center through a cooperative agreement with EPA. The scope of the AMS Center covers verification of monitoring technologies for contaminants and natural species in air, water, and soil.
The day to day operations of this verification test will be coordinated and supervised by Battelle, with the participation of the vendor (Picometrix) who will be having the performance of their technology (Picometrix, LLC T-Ray 4000® Time-Domain Terahertz System) verified. The Picometrix technology offers an alternative to using sealed radioactive source nuclear gauges. Testing will be conducted at Appleton Paper in Appleton, Wisconsin. The vendor will provide and operate their technology.
Here is more:
Radioisotopes, such as sealed sources of Strontium-90, Krypton-85 or Promethium-147, can be found in industrial devices used to measure the mass per unit area (basis weight) of various manufactured products such as sheet metal, textiles, paper, photographic film, and other pressed or sheet (flat) material. Devices widely used in industrial and commercial applications are often small in size, and could potentially be lost, stolen, abandoned, or improperly disposed. In some instances sealed radioactive sources can be replaced by an alternative non-radioactive source of energy to accomplish the same function.
Currently, nuclear gauges are being used to measure or control material density, flow, level, thickness or basis weight. The gauges contain sealed sources that radiate through the substance being measured to a readout or controlling device. The radiation that is emitted from the gauge is attenuated by the matter between the radioisotope and the detector. The radiation reduction can be correlated to the quantity of matter between the source and the detector. The
nuclear radiation is attenuated by the number of atoms between the source and the detector. The physical measurement is the magnitude of radiation that passes through the material. The actual amplitude of the detected signal must be compensated for a number of factors (e.g. moisture, air in the intervening space, geometry of the source and detector); however these factors are well understood and implemented in commercial nuclear gauges.
Nuclear gauges have been widely used (since the 1940’s) for the measurement of basis weight and quantities that can be derived from basis weight (e.g. thickness, coat weight) because of their ability to penetrate most materials, their long life (depending on isotope) and their low cost. At this point in time they are a well established, low risk gauge that is well known in the industry. However, the radioactive sources in these gauges can present a safety risk. Minimizing the number of radioactive sources in the public domain will decrease the opportunity for individuals to use the radioisotopes for unintended, harmful (i.e. terrorist) purposes. In an effort to do so, the EPA's Office of Radiation and Indoor Air in the Office of Air and Radiation (OAR), established the EPA's Alternative Technologies Initiative (ATI) (http://www.epa.gov/radiation/source-reduction-management/alt-technologies.html). Part of the EPA-ATI is fostering the acceptance and voluntary market adoption of non-radioactive technologies; i.e., alternative technologies to those that currently use sealed sources. The EPA-ATI is focusing primarily on alternative technologies for devices with Category 3 and 4 radioactive sources as classified by the International Atomic Energy Agency (IAEA) . Commercial-ready or available alternatives to nuclear gauges (such as infrared, laser, and other technologies) are being considered. As with any new technology, the likelihood of acceptance can be significantly increased by independent evaluation and verification of a technology's capabilities.
The purpose of this QAPP is to specify procedures for a verification test applicable to commercially available alternatives to nuclear gauges that can replace technologies using sealed radioactive sources for the measurement of basis weight, the measurement of mass per unit area of a material. The purpose of the verification test is to evaluate the performance of the Picometrix T-Ray 4000® Time-Domain Terahertz (THz) System in an actual production environment for the measurement of basis weight.
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