Reducing the Use of Highly Enriched Uranium in Civilian Research Reactors (2016) / Chapter Skim
Currently Skimming:
3 Research Reactors and Their Uses
3 Research Reactors and Their Uses
Pages 37-54
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 37... ...
The trend is clear: A flux of thermal neutrons in the reactor core of roughly 1015 neutrons per square centimeter per second (n/cm2-s) was achieved in the mid-1960s and has not been greatly exceeded since (see Table 3.1 for the listing of maximum flux for the highest-performance existing research reactors)
|
From page 38... ...
USES OF RESEARCH AND TEST REACTORS Research reactors are indispensable tools in the education and training of reactor operators and nuclear engineers, basic and applied research in a wide range of scientific areas, and the production of scientifically and tech nologically important materials, such as radioisotopes. Such reactors are also used for testing new types of nuclear fuel and studying the radiation resistance of new materials and electronic devices.
|
From page 39... ...
Irradiation Applications Irradiation applications of research reactors generally involve inserting specimens into the reactor (in either the in-core or near-core regions where the neutron flux is highest) to induce radioactivity, produce isotopes, or induce radiation damage.
|
From page 40... ...
Production of these isotopes in research reactors is based on neutron absorption by a target material introduced into the reactor core. In general, the quantity of an isotope that can be produced in a given amount of time will increase as the neutron flux increases.
|
From page 41... ...
For accelerator-based isotope production applications, the flux gradient results in reduced throughput; for accelerator-based transmutation doping applications, such gradients are counter to a primary advantage of the transmutation doping approach -- uniform production of dopants. Research Reactors for Materials Testing An important class of research reactors, often referred to as Materials Test Reactors (MTRs)
|
From page 42... ...
The Advanced Test Reactor (ATR) in the United States, BR2 in Belgium, and MIR.M1 in Russia are particularly important high-flux research reactors used for materials testing.
|
From page 43... ...
4 However, the in-core and near-core applications cannot benefit from improvements in beamline instrumentation for increased flux; for those applications, neutron flux depends on the reactor design and sample placement.
|
From page 44... ...
Because the neutron-scattering signal is limited by the neutron flux that can be directed at a sample, its most advanced implementation is restricted to high-intensity neutron sources, either HPRRs or advanced pulsed spallation neutron sources. High-power spallation sources utilize protons from a particle accelerator to bombard a target made of a heavy element such as tungsten or mercury.
|
From page 45... ...
In addition to the summary in Table 3.1, a brief description of each reactor and its mission is given below. TABLE 3.1 High Performance Research Reactors of Relevance to the Conversion Study Research Maximum Reactor Thermal Neutron (Neutron Start of Power Thermal Flux Source)
|
From page 46... ...
. It is a leading location for accelerated testing of mate rials for nuclear energy applications, including fuel for LEU conversion of research reactors.
|
From page 47... ...
HFIR was originally constructed for the production of heavy transuranic isotopes requiring multiple neutron captures, for example, 252Cf. Although it is still the only reactor outside of Russia to efficiently produce such isotopes, its mission is currently dominated by neutron-scattering experiments following the installation of a cold neutron source in one of its beamlines.
|
From page 48... ...
since 1971. The primary mission of RHF is to produce neutron beams to conduct neutron science supported by more than 40 instruments in a reactor hall plus two guide halls.
|
From page 49... ...
is scheduled to begin operation in 2019, and the spallation source at ISIS7 has recently been upgraded with an additional target station.8 RHF at ILL has long been a leading facility for neutron science reactor applications worldwide and has been significantly upgraded at various times during its history.9 For materials testing, BR2 is an important international resource, including for the testing of the highdensity monolithic UMo fuel being developed by the United States during periods when ATR is unavailable. Its operator acknowledges, however, that BR2 will likely reach end of life within the next 15–20 years.
|
From page 50... ...
JHR will also add to European materials testing and irradiation capability but will not support extracted beam applications. Finally, the 45-MW High Flux Reactor at Petten, the Netherlands (previously converted to LEU fuel, and so it is not discussed above)
|
From page 51... ...
Finding 4: The mission and capability of some high performance research reactors have evolved to accommodate changing user needs and to expand the user base, with the consequence that the reactors are sometimes not specifically designed for current missions. Current analyses indicate that the variety of missions spanned by the USHPRRs can be accomplished with the reactors operating with a new high-density monolithic LEU fuel.
|
From page 52... ...
Although this arrangement has ensured that each of the important and existing customer bases for research reactors has at least one HPRR that serves its needs, it also means that communication and coordination among the full research reactor community -- operators, users, and sponsors -- in the United States is difficult and limited. As an example, a DOE Nuclear Energy–National Nuclear Security Administration Research Reactor Working Group11 in 2013 considered future options for research reactors in the United States, but explicitly recognized that it could only consider reactors and applications within DOE's scope of responsibility (DOE, 2013b)
|
From page 53... ...
in 2030, it is reasonable to compare the benefit of U c onverting/retrofitting the current fleet of USHPRRs against designing and building new research reactors that use low enriched uranium fuel and address the critical missions the current reactors support. Recommendation 1: The U.S.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.