New York City’s Greenwich Village, famous as an art and literary center, is also the unlikely gathering place for scientists supporting Environmental Management’s site closure and cleanup efforts. They work at DOE’s Environmental Measurements Laboratory, assessing the quality of environmental radiological measurements reported by contractor and subcontractor labs. Accurate and precise information from such labs is essential for important characterization, remediation, and long-term monitoring decisions.

Quality assurance is a prime example of EML’s services to EM and other government, national, and international organizations. The lab, which is one of only five government-owned and government-operated labs in DOE, has been in existence for more than 50 years and employs experts in radiation and radioactivity metrology. The quality assessment staff are known around the world for developing and implementing methodologies that have been incorporated into two external, independent performance evaluation programs—the Quality Assessment Program (QAP) and the Gamma Spectrometry Data Evaluation Program (GSDEP).

Quality Assessment Program
QAP provides a way for DOE contractor and subcontractor labs to substantiate their ability to analyze low-level radionuclides at contaminated sites. Labs routinely analyze soil, water, vegetation, and air filter samples from DOE sites, measuring the emission of gamma rays and alpha and beta radiation to determine what radioactive elements are present and in what quantities. Twenty-six labs participated in the first QAP in 1976. More than 170 labs participated in the most recent QAP.

To test their analytical methods and instruments, EML sends each lab a variety of sample media containing radioactive nuclides. Water and air filters are spiked with a mixture of known alpha, beta, and gamma emitters; vegetation and soil are spiked with a naturally contaminated material; and another set of water and air filter samples is spiked with an alpha and a beta emitter for gross alpha/beta measurements. After these samples have been analyzed, each lab sends its results to EML, where they are checked against the EML “reference” value. A summary evaluation is available to the participants and others via the EML Web site (www.eml.doe.gov) 48 hours after the reporting deadline.

Michael Heeb, member of the Laboratory Management Team for the Office of Science and Technology, said, “The fundamental basis of environmental cleanup depends on the quality, reproducibility, and accuracy of the data from sample analyses. EML plays a critical role in the pathway to success for EM.”

Accurate, defensible data improves risk assessments, thus enabling program managers to make better and more cost-effective decisions, leading to a healthier environment for cleanup workers and the public. For example, the technologies that are most appropriate for a given cleanup problem are determined in large part by the extent of the radiological contamination and how accurately it is measured.

Gamma Spectrometry Data Evaluation Program
EML’s GSDEP is a voluntary performance evaluation service designed to improve labs’ gamma spectrum analyses (a technique for identifying many different nuclides). GSDEP sends labs a computer disk or tape with synthetic spectra to test the accuracy of a labs’ gamma-ray spectrometry software and the ability of the user to properly utilize the software.

In the usual nuclide analysis process, samples are “counted” on a germanium detector, which along with its associated electronics separates the gammas according to energy. The resulting spectra are analyzed either with commercially available or in house–developed software to identify the nuclides and determine the amount of each nuclide present.

Many of the available commercial data reduction software programs are easy to use and do not require the user to be an expert in gamma spectrometry. Use of these products can lead to errors because even the best programs occasionally give inaccurate results without user intervention. “People assume that the software does everything correctly,” said Karin Decker, EML chemist. “That’s not always the case.” GSDEP helps labs identify errors and avoid mistakes such as reporting false positives. “We try to teach people by pointing out common weak points of software or areas where user intervention may be needed,” Decker added.

“It’s an extremely useful program,” said Larry Hatcher, a health physicist with Bechtel Nevada. “It evaluates more than just your equipment. It evaluates the capacity of people looking at the data.”

The synthetic approach enables EML to provide very complicated radionuclide spectra to challenge a lab’s analytical and interpretive abilities. “It’s not a substitute for using actual physical samples,” Decker said. “It’s another way to improve your analysis technique. Labs have also used it as a training tool for people who are just starting to learn gamma spectrometry.”

GSDEP is offered every two years. Thirty-one labs participated in the last GSDEP. The next evaluation is scheduled to start in November 2001.

Other EML services
EML’s quality assessment staff may also train or assist labs that are having trouble with a particular analysis. “Also, if there’s a difficult or politically sensitive project, EML may act as the quality assurance referee,” Decker said. For example, EML analyzed sediment samples from the Peconic River on the Brookhaven Site to ensure that the project contractor’s results were accurate.

In addition to EML’s data quality assurance programs staff, the lab employs experts who support OST in the development and deployment of radiological field characterization and monitoring technologies, provide technical assistance to DOE field offices, and support efforts toward global nuclear nonproliferation. In the past, EML scientists conducted assessments of radiation exposure from the Three Mile Island and Chernobyl accidents. Presently, the lab is providing technical assistance through the Subsurface Contaminants Focus Area and the Joint Coordinating Committee for Environmental Restoration and Waste Management (EM’s cooperative international initiative with Russia, see Initiatives, December 1997 and Spring 2000).

For most of us, the rich history of Greenwich Village as an arts center, restaurant locale, and social bellwether come immediately to mind. In the scientific world of radiation and radioactivity and quality assurance, “Greenwich Village” means EML and the help its scientists provide to the worldwide radiation community.

If you want to participate in either QAP or GSDEP, contact Raymond Bath, raymond.bath@eml.doe.gov. For more information on these and other EML programs, visit www.eml.doe.gov.