The NRL has multiple vertical in-core dry tubes (two 2.5 inch I.D. tubes) as well as movable vertical ex-core dry tubes (6.5 inch and 9.5 inch I.D. tubes) available for experiments. These tubes extend from the pool top down to the reactor core such that instrumented experiments can be installed for real-time, in-situ measurements in a neutron and gamma radiation field. Instrumented experiments for evaluation of advanced sensor prototypes and sensor materials can be designed for test in these dry tubes. To complement data collected by the user, the NRL can provide an analog reactor power signal that can be integrated into the user's data acquisition. The available neutron flux varies by dry tube, but experiments with neutron fluence up to ≈1x1018 n/cm2 can typically be performed.
The movable vertical ex-core dry tubes can be loaded with an experiment and positioned against the east face of the reactor core, allowing for a wide range of reactor irradiation experiments. For instance, instrumented high-temperature furnaces have been used in these tubes to investigate material effects in fiber optics in a high-temperature radiation environment. Furnace rigs up to 1200 °C have been used, and a rig for a 1600 °C experiment is being developed. Instrumented ultra-cold experiments have also been run in the 10 inch tube using a cryostat to cool fiber optics and electronics to about 4 Kelvin while being irradiated by the reactor. With the reactor at maximum power, the neutron flux in either of these dry tubes positioned next to the core is ≈1x1012 n/cm2/s, and experiments with neutron fluence on the order of 1x1017 nv can typically be performed.