The shutdown gamma flux in the specimen rack is approximately 3 R/min. Central thimble The central thimble, which is a water-filled irradiation chamber about in diameter, provides the highest available neutron flux, about 1.4x1013 n/cm2/s. However, it holds only one specially positioned irradiation container, containing a cavity in length and in diameter. Another in-core location is available by replacing one of the fuel elements with an irradiation chamber. The chamber fits into a fuel-element position within the core itself. Foil-insertion holes, in diameter, are drilled at various positions through the grid plates. These holes allow inserting special holders containing flux wires into the core, to obtain neutron flux maps of the core. In-pool facilities Near core, in-pool irradiation facilities can be arranged for larger samples. Neutron fluxes will be lower than in the lazy susan and will depend on the sample location. References External links 1968 establishments in Oregon Nuclear research reactors Reed College campus