Pneumatic Tube Facilities
The MITR is equipped with two pneumatically-operated irradiation facilities that allow materials to be exposed to high or intermediate-level neutron fluxes. A 2” pneumatic facility (2PH1) offers a high thermal flux of up to 6x1013 n/cm2-s with a significant fast neutron flux (cadmium ratio of about 20). A 1” pneumatic facility (1PH1) offers an intermediate, highly thermal flux of up to 8x1012 n/cm2-s (cadmium ratio of about 200). These facilities are normally used to support MIT-NRL’s Neutron Activation Analysis program and for isotope and radiotracer production.
Materials are transferred through the pneumatic facilities in sample holders known as ‘rabbits.' The 1PH1 system uses a polyethylene rabbit with internal dimensions of 1” diameter by 3-1/4” length; the 2PH1 system uses either polyethylene or titanium rabbits with internal dimensions of 1-3/8” diameter by 6-1/4” length. Titanium rabbits are generally only used for 2PH1 irradiations longer than 10 hours.
The 1PH1 pneumatic system is capable of ejecting the sample to a hot cell within the reactor containment or to a laboratory in an adjacent building. This allows materials to be irradiated for short periods (typically from 10 seconds to 10 minutes) and examined within minutes.
The following shows sample holders or ‘rabbits’ used in the 1PH1 (a), and 2PH1 (b and c) pneumatic irradiation systems. The titanium rabbit (c) is generally used only for 2PH1 irradiations longer than 10 hours in duration.
Left to right: Polyethylene 1-inch rabbit; Polyethylene 2-inch rabbit; Titanium 2-inch rabbit.