OBSERVATIONS FROM THE FIRST YEAR OF THE DEEP BOREHOLE FIELD TEST
The scope of the first phase of the DBFT project includes drilling a deep characterization borehole to 5 km, conducting downhole scientific sampling and testing, and supporting experimental programs. In a second phase, a larger-diameter field test borehole will be drilled to 5 km to test protocols for emplacing and retrieving simulated waste packages and other engineering aspects of deep borehole disposal (DBD); however, no nuclear waste will be used in either phase of the DBFT. The DBFT boreholes are to be drilled at a site with technical characteristics representative of those considered best for DBD.
Since inception of the project, significant effort has gone into preparing for drilling and testing the characterization borehole. A comprehensive drilling plan was developed that defines the major elements of a drilling program, including: casing, cement program, drilling rig and other equipment (e.g., drilling bits) requirements, drilling fluids and solids control program, coring program, etc. Test methods were developed for characterizing key geologic properties of the crystalline rock, including hydraulic-properties (e.g., permeability, hydraulic gradient), stresses, and water chemistry. Specifications for testing equipment were developed for the anticipated downhole pressures and temperatures; and, new testing equipment was designed to accommodate special testing requirements.
To date, drilling and testing of the characterization borehole has not begun, despite the comprehensive planning efforts, because a site has not yet been secured. Two sites were identified that have highly desirable geology, one in North Dakota and one in South Dakota. But, in both cases, opposition from the local community halted implementation, despite being on private land and having approval at the state level in one case. DOE’s preference is to obtain the approval of the local community at the site where the DBFT is executed and thus far this has proved to be difficult.