The DOE tasked PNNL to investigate possible technological avenues for substantially advancing the state-of-the-art in gamma detection via large-area plastic scintillators. This report describes progress on this project as of the conclusion of FY 2003. The primary focus of the report is on experimental tests conducted with a single large-area plastic scintillator outfitted with a variety of photomultiplier tube configurations. Measurements performed to date incude scintillator response under broad-area exposure to various point-like gamma sources, and light-output uniformity mappings obtained by varying the position of a collimated beta-source over the surface of the scintillator. Development of a Monte Carlo program for modeling the response of a large-area scintillator sensor to ionizing radiation, explicitly including resolution-broadening effects of scintillation light generation, propagation, and collection is also described.

This report describes the seismic activity in and around the Hanford Site during Fiscal year 2003. Hanford Seismic Monitoring provides an uninterrupted collection of high-quality raw and processed seismic data from the Hanford Seismic Network for the U.S. Department of Energy and its contractors. Hanford Seismic Monitoring also locates and identifies sources of seismic activity and monitors changes in the historical pattern of seismic activity at the Hanford Site. The data are compiled, archived, and published for use by the Hanford Site for waste management, Natural Phenomena Hazards assessments, and engineering design and construction. In addition, the seismic monitoring organization works with the Hanford Site Emergency Services Organization to provide assistance in the event of a significant earthquake on the Hanford Site. The Hanford Seismic Network and the Eastern Washington Regional Network consist of 41 individual sensor sites and 15 radio relay sites maintained by the Hanford Seismic Monitoring staff. For the Hanford Seismic Network, there were 1,336 triggers during fiscal year 2003. Of these triggers, 590 were earthquakes. One hundred and one earthquakes of the 590 earthquakes were located in the Hanford Seismic Network area. Stratigraphically 35 (34.6%) occurred in the Columbia River basalt, 29 (28.7%) were earthquakes in …

Application of two electrical resistivity methods at the Hanford Site Mock Tank during 2002, indicate the viability of the methods as possible leak-detection tools for SST retrieval operations. Electrical Resistivity Tomography and High-Resolution Resistivity were used over a 109-day period to detect leakage of a waste simulant beneath the tank. The results of the test indicate that both of these two methods, and subset methods may be applicable to SST leak detection.