Experimental Facilities

The MIT Nuclear Reactor Lab has an extensive array of facilities for performing neutron and gamma irradiations, for studying neutron physics, and for examining radioactive materials. For a comprehensive description of the NRL's experimental facilities, download the NRL's User's Guide. A short table of the representative dimensions and maximum flux levels for the neutron irradiation facilities is below. A summary of the MITR’s experimental facilities is below. Some of the facilities are described more fully on their own pages.


The MITR has the capability to perform a wide range of experiments in the reactor’s core. In-core experimental facilities are not permanently installed in the reactor. Facilities that are reused are stored in shielded locations in the reactor’s containment building. A complete table of the previous in-core experiments is here. A brief list of the types of facilities that are available includes:

  • An inert gas-filled irradiation tube (ICSA) for sample capsule irradiation at <900 °C (instrumented or un-instrumented),
  • Forced-circulation coolant loops that replicate conditions in both pressurized and boiling water reactors,
  • High temperature (>900 °C) irradiation facility for materials irradiations in inert gas (He/Ne mixture), and
  • Custom, dedicated facilities for irradiations in unique conditions (e.g., molten fluoride salts).

Beam Ports

The MITR has numerous neutron beam ports surrounding the reactors biological shield including:

  • One 12-inch diameter port, radial,
  • Two 6-inch diameter ports, radial,
  • One 6-inch diameter through-port,
  • Four 4-inch diameter radial ports, and
  • One 4-inch diameter through-port.

Pneumatic Tubes

Two systems are available to perform neutron irradiations on small samples by pneumatically inserting them into positions near the MITR core:

  • 2PH1 – 2” high flux pneumatic tube, and the
  • 1PH1 – 1” intermediate flux pneumatic tube.

Gamma Irradiation Facility

  • Sample irradiation space can be provided in the spent fuel pool for gamma exposure from fission product decay. Facility can be instrumented if required.

Neutron Scattering

The MITR has two neutron scattering facilities:

  • Triple-axis diffractometer equipped with PG monochromator, PG analyzer, He-3 monitors, and detector and standard collimators, slits, and PG filters, and
  • Neutron optics test station with polychromatic neutron beam.

Elemental Analysis Facilities

Elemental analyses can be performed at the MTR using:

  • Neutron Activation Analysis (NAA),
  • Prompt Gamma Neutron Activation Analysis (PGNAA), and
  • Inductively Coupled Plasma - Optical Emission Spectrometer (ICP-OES)

Post-Irradiation Examination (PIE) Facilities

The MITR has a wide range of facilities that are useful for handling and examination of highly radioactive materials. These include:

  • Hot cells and for remote handling of irradiated components and materials,
  • Hot sample preparation facilities,
  • Helium-filled glove box with high-temperature furnace and gamma shielding
  • Electron microscopy facilities, and
  • Access to electron microscopy facilities can be arranged for irradiated samples.

Graphite-Reflector (3GV)

  • Two large, vertical, thermal neutron irradiation facilities are located in the MITR graphite reflector.

Shielded Medical Irradition Rooms

  • Medical room with horizontal epithermal beam from a fission converter (currently de-fueled), and a
  • Medical room below core with vertical thermal beam.

Time-of-Flight Experimental Facility

  • This facility can be operated locally or remotely over the internet for student experiments in neutron energy distributions, attenuation, and scattering. Also available for neutron detector testing or cross-section measurements.


Representative Dimensions and Maximum Neutron Flux Levels in MITR Irradiation Facilities

Facility Size Neutron Flux (n/cm2-s)
In-core Three positions available
Maximum space ≈ 1.8” diameter × 24” long
Thermal: 3.6 × 1013
Fast (E>0.1MeV): 1.2 × 1014
Beam ports Various diameters from 4-inch to 12-inch Thermal (source):
1 × 1010 – 1 × 1013
Vertical irradiation position (3GV) Two positions available
Maximum space ≈ 3” diameter × 24” long
Thermal: 4 × 1012 – 1 × 1013
Through ports One 4-inch port (4TH)
One 6-inch port (6TH)
Average thermal:
2.5 × 1012 – 5.5 × 1012
Pneumatic tubes One 1-inch tube (1PH1)
One 2-inch tube (2PH1)
Thermal: 9 × 1012 – 6 × 1013
Fission Converter Beam (FCB) Beam aperture ≈ 6-inch diameter Epithermal: ≈ 5 × 109
Thermal Beam (TNB) Beam aperture ≈ 6-inch diameter Thermal: up to 1 × 1010