Transient Reactor Test Facility (TREAT)

Coordinates: 43°41′11″N 112°45′36″W / 43.68647°N 112.75998°W / 43.68647; -112.75998

TREAT
Location in the United States
TREAT
Location in Idaho, west of Idaho Falls

The Transient Reactor Test Facility (TREAT) is an air-cooled, graphite moderated, thermal spectrum test nuclear reactor designed to test reactor fuels and structural materials.[1] Constructed in 1958, and operated from 1959 until 1994, TREAT was built to conduct transient reactor tests where the test material is subjected to neutron pulses that can simulate conditions ranging from mild transients to reactor accidents. TREAT was designed by Argonne National Laboratory,[2] and is located at the Idaho National Laboratory. Since original construction, the facility had additions or systems upgrades in 1963, 1972, 1982, and 1988. The 1988 addition was extensive, and included upgrades of most of the instrumentation and control systems.[3]

TREAT Reactor (south side)

The U.S. Department of Energy (DOE) has decided to resume a program of transient testing,[4][5][6][7][8] and plans to invest about $75 million to restart the TREAT facility by 2018. The renewed interest in TREAT was sparked by the 2011 Fukushima Daiichi nuclear disaster, which prompted the shutdown of Japan's and Germany's nuclear plants. One use for TREAT is planned to be testing of new accident tolerant fuel for nuclear reactors.[9][10]

Fuel and Core Description

The TREAT fuel assemblies are approximately 9 feet long, and 4 inches square in cross section. The fuel is a graphite uranium mixture, with 1 part uranium to 10,000 parts graphite. The active portion of the fuel assembly is about 48 inches, with a graphite reflector of about 24 inches above and below the active portion. The active portion of the fuel assemblies are encased with Zircaloy. There is also a graphite axial reflector, composed of two parts. The first part of the axial reflector consists of movable assemblies similar to the fuel assemblies, but containing only graphite and no fuel. The second part of the axial reflector consists of permanent blocks of graphite, approximately 24 inches thick, stacked outside the core cavity. This permanent reflector was reclaimed from Chicago Pile-1, the world's first nuclear reactor. The core may be loaded to a size of 5 feet by 5 feet (nominal) up to 6 feet by 6 feet (maximum), depending on the needs of the experiment.[11][12]

As described above, the fuel is composed of a mixture of graphite and uranium. The uranium is in the form of uranium oxide particles that are approximately 20 microns in size, and are in direct contact with the graphite moderator. The graphite, in addition to being the neutron moderator, also acts as a large thermal heat sink. The time lag of the heat transfer is on the order of 1 millisecond, much faster than the heat transfer to a liquid coolant flowing past fuel assemblies. Also, when the graphite is heated it creates a sizable negative moderator temperature coefficient. These characteristics allow TREAT to produce large ‘self-limited’ transients, which are limited by the fuel negative moderator coefficient without control rod movement.[12]

Experimental Capabilities

TREAT is capable of a wide range of operations and test conditions. TREAT can operate at a steady state power of 100 kW, produce short transients of up to 19 GW, or produce shaped transients controlled by the TREAT automatic reactor control system and the Control Rods. A test assembly can be inserted in the center of the core. The test assembly is a self-contained vehicle, that can contain fuel or materials for a variety of reactor types.[13] These test assemblies, also referred to as test vehicles or test loops, can simulate the conditions of a light water reactor, heavy water reactor, liquid metal fast breeder reactor, or a gas cooled reactor.[14]

Hodoscope

TREAT has a fast-neutron hodoscope that collimates and detects fast fission neutrons emitted by experiment fuel sample.

The TREAT hodoscope consists of a front collimator, a rear collimator, a bank of detectors, electronics to interface to the detectors, and a data acquisition system. The collimator has 10 columns with 36 rows, which are aligned to an array (or arrays) of 360 detectors. The hodoscope provides time and spatial resolution of fuel motion during transients and in-place measurement of fuel distribution before, during, and after an experiment.[14][15] One array of detectors consists of Hornyak Button detectors.[16] The Hornyak Button is a fast neutron detector that consists of a film of ZnS applied to lucite, which together form the 'button'. The button is attached to a photomultiplier tube. This detector shows good efficiency at detecting fast neutrons in a background of thermal neutrons and gamma radiation.[17]

Neutron Radiography Facility

TREAT has a neutron radiography facility on the west face of the reactor. This allows non-destructive examination of experiment test assembly (or other materials) up to 15 feet in length. TREAT can operate at steady state power levels of up to 100 kW to product neutrons for the radiography facility.[2][13]REAT

TREAT Systems

Control Rod Drive Systems

TREAT Control Rod Drive Mechanisms

TREAT has three banks of control rod drive mechanisms, the control/shutdown rods, the compensation/shutdown rods, and the transient rods. There are 4 drive mechanisms in each group. The drive mechanisms are below the reactor, and raise the control rods out of the reactor to increase reactivity. [18] These banks of control rods are arranged in two rings. The inner ring contains four drive mechanisms, the compensation/shutdown rods, with one control rod for each drive mechanism. The outer ring has four control/shutdown drive mechanisms and four transient rod drive mechanisms. The control/shutdown and transient rod drive mechanisms have two control rods for each drive mechanism. All the control rods contain B4C poison sections. The compensation/shutdown and control/shutdown drive mechanisms are mechanical lead screw driven, and have use pneumatic pressure to assist the scram function. The four transient rod drives are hydraulically actuated, and are controlled by the ARCS to control transients. These transient rods move up to 170 in/sec over a total travel of 40 inches.[19]

General Reference

Stacy, Susan M. (2000) Proving the Principle: A History of the Idaho National Engineering and Environmental Laboratory, 1949-1999. United States Government Printing. pp. 136, 268. ISBN 0160591856.

Specific References

  1. ↑ Kelly, John E.; Wright, Steven Alan; Tikare, Veena; MacLean, Heather J. (Idaho National Laboratory; Parma, Edward J.; Peters, Curtis D.; Vernon, Milton E.; Pickard, Paul S. (2007-10-01). "Global Nuclear Energy Partnership Fuels Transient Testing at the Sandia National Laboratories Nuclear Facilities: Planning and Facility Infrastructure Options.".
  2. 1 2 "Fast Reactor Technology - Reactors designed/built by Argonne National Laboratory". www.ne.anl.gov. Retrieved 2015-08-21.
  3. ↑ "INL Fact Sheet - Transient Reactor Test Facility". Retrieved 2015-07-25.
  4. ↑ "Idaho brings nuclear test reactor back to life". Associated Press. Associated Press. 5 October 2014. Retrieved 7 August 2015.
  5. ↑ RAMSETH, LUKE (3 October 2014). "Bringing a nuclear test reactor back to life at INL". Post Register (Idaho Falls, ID).
  6. ↑ "DOE issues Finding of No Significant Impact for the Environmental Assessment on Resumption of Transient Testing of Nuclear Fuels and Materials at Idaho National Laboratory". US Department of Energy, Office of Nuclear Energy, Initiatives, Nuclear Facility Operations. Retrieved 26 July 2015.
  7. ↑ "Resumption of Transient Testing". US Department of Energy, Office of Nuclear Energy, Initiatives, Nuclear Facility Operations. Retrieved 26 July 2015.
  8. ↑ "TREAT Reactor Restart". Snake River Alliance. Retrieved 7 August 2015.
  9. ↑ Ballard, Dorothy (2014-10-07). "TREAT nuclear reactor to reopen after 20 years of inactivity". PennEnergy. PennWell. Retrieved 25 July 2015.
  10. ↑ "Development of Light Water Reactor Fuels with Enhanced Accident Tolerance – Report to Congress". US DOE. Retrieved 10 October 2015.
  11. ↑ Heath, Bradley K. "Parametric Thermal Models of the Transient Reactor Test Facility (TREAT)". US Department of Energy. Retrieved 8 August 2015.
  12. 1 2 Okrent, D.; Dickerman, C. E.; Gasidlo, J.; O'Shea, D. M.; Schoeberle, D. F. (1960-09-01). "The Reactor Kinetics of the Transient Reactor Test Facility (TREAT)". OSTI 4117807. ANL-6174.
  13. 1 2 Carmack, Jon. "Future Transient Testing of Advanced Fuels". US Department of Energy. Retrieved 8 August 2015.
  14. 1 2 CRAWFORD, D.C.; SWANSON, R.W.; WRIGHT, A.E.; HOLTZ, R.E. "RIA TESTING CAPABILITY OF THE TRANSIENT REACTOR TEST FACILITY" (PDF). International Atomic Energy Agency (IAEA). Retrieved 2 September 2015.
  15. ↑ Rhodes, E.; DeVolpi, A.; Fink, C.; Stanford, G.; Pecina, R.; Travis, D.; Kash, R. "TREAT FAST-NEUTRON HODOSCOPE: IMPROVEMENTS IN TIME AND MASS RESOLUTION OF FUEL MOTION". OSTI. US DOE. Retrieved 9 October 2015.
  16. ↑ DeVolpi, A.; Fink, C.L.; Marsh, G.E.; Rhodes, E.A.; Stanford, G.S. (1980). FAST-NEUTRON HODOSCOPE AT TREAT: METHODS FOR QUANTITATIVE DETERMINATION OF FUEL DISPERSAL. Argonne National Lab. Retrieved 18 October 2015.
  17. ↑ Hornyak, W. F. (1951-10-17). "A Fast Neutron Detector". OSTI 4396836. Retrieved 2015-10-18.
  18. ↑ Bess, John Darrell; DeHart, Mark David (2015-10-01). "Baseline Assessment of Treat for Modeling and Analysis Needs". Idaho National Laboratory (INL), Idaho Falls, ID (United States).
  19. ↑ Wade, D. C.; Bhattacharyya, S. K.; Lipinski, W. C.; Stone, C. C. (1982-01-01). "Core Design of the Upgraded Treat Reactor". Argonne National Lab., IL (USA).
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