DNAA works with excellent speed, sensitivity, and specificity, but few such systems exist worldwide. NCNR is an excellent facility to take advantage of this analytical method because of the intense thermal flux available with a minimal proportion of fast neutrons. These highly desirable characteristics mean that interference from fast-neutron reactions produced from ubiquitous thorium and oxygen are negligible. Overall, DNAA is well-tested, rapid, specific, matrix-independent, nondestructive, and sensitive. Consequently, the analysis process is greatly simplified and detection limits enhanced. The technique is sensitive solely to nuclides that fission with delayed emission of neutrons to give an unambiguous indication of controlled material. At the NIST DNAA facility, less than one nanogram of fissile species (e.g., 233U, 235U, 239Pu, 241Pu, 241Am, 243Cm, 244Cm, 245Cm, 252Cf) can be detected, and the analysis requires less than 3 min. Furthermore the system can process a great variety of sample types that might host the fissionable particles hidden in volumes as large as 40 mL. In the last year researchers from Oak Ridge National Laboratory (ORNL) and our team successfully demonstrated that the newly installed DNAA system response is strictly linear over at least a 25-fold concentration range of 235U (see plot above). This demonstrated ability enabled the system to immediately be used for the analysis of samples from ORNL. Recently, the sample transfer system was automated, leading to increased sample throughput and improved sensitivity. As the technique is further developed it will be used to certify the trace uranium in Standard Reference Materials. With the completion and verification of the DNAA system, NIST has a readily accessible, rapid means of measuring traces of fissionable U and Pu in samples of forensic interest for homeland security and for characterizing Standard Reference Materials.