Research reactor

Many types of research reactor exist for physics and materials research, for irradiation, for isotope production. They are also used now for direct medical use. A very widely used type worldwide is the pool reactor with various types of fuel elements. 

From the safety point of view, usually these reactors have a small internal energy (no pressure circuit) and the intrinsic characteristic of neutron stabdity. They generally do not need a pressure container and are located in leakproof buildings with a small design pressure difference from the outside. 

Relatively high power research reactors do exist (up to 100 MWt) for which the safety issue is more complex. 

An example of this would be the reactor called VERA, which was commissioned at Aldermaston in Fehruary 1961. A description of the reactor states that 

Up to April 1963 the reactor was used for studies of assemblies containing U235 and U238 mixed with various amounts of graphite and polythene. Work with 

Xenon poisoning is thought to be one of the causes of the explosion of the reactor at Chernobyl. When the reactor was powered down, there were few neutrons available to remove the xenon 135, but it was still being produced from the decay of the iodine 135, and so its concentration increased. When the operators attempted to increase the power of the reactor, the extra neutrons were being absorbed by the xenon. They then removed the control rods further to force the pile into greater 

Although many of the names of the reactors can be seen as acronyms, their derivation was somewhat fanciful. The first heavy water reactor was christened DIDO — heavy water being deuterium oxide, D2O, or, stretching things, DDO — hence DIDO. Another example was a new heavy water zero-energy reactor being built at Harwell in 1960. A note was sent to tbe Director  

I gather that in the past it has been the prerogative of the Director to select a name for large pieces of equipment... we have had some names suggested for the new reactor and they fall into two categories — those formed from abbreviations and those which are symbolic. You may like to choose from this list, or suggest an alternative yourself.  

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As with synchrotron x-rays, neutron diffraction facilities are available at only a few major research institutions. There are research reactors with diffraction facilities in many countries, but the major ones are in North America, Europe and Australia. The are fewer spallation sources, but there are major ones in the United States and the United Kingdom. 

The neutrons in a research reactor can be used for many types of scientific studies, including basic physics, radiological effects, fundamental biology, analysis of trace elements, material damage, and treatment of disease. Neutrons can also be dedicated to the production of nuclear weapons materials such as plutonium-239 from uranium-238 and tritium, H, from lithium-6. Alternatively, neutrons can be used to produce radioisotopes for medical diagnosis and treatment, for gamma irradiation sources, or for heat energy sources in space. 

Directory of Nuclear Research Reactors, International Atomic Energy Agency, Vienna, Austria, 1989. 

Other fuel besides that from U.S. commercial reactors may be disposed of in the ultimate repository. PossibiUties are spent fuel from defense reactors and fuel from research reactors outside of the United States. To reduce the proliferation of nuclear weapons, the United States has urged that research reactors reduce fuel enrichment in uranium-235 from around 90 to 20%. The latter fuel could not be used in a weapon. The United States has agreed to accept spent fuel from these reactors. 

From spent power and research reactor fuel. 

A large number of radiometric techniques have been developed for Pu analysis on tracer, biochemical, and environmental samples (119,120). In general the a-particles of most Pu isotopes are detected by gas-proportional, surface-barrier, or scintillation detectors. When the level of Pu is lower than 10 g/g sample, radiometric techniques must be enhanced by preliminary extraction of the Pu to concentrate the Pu and separate it from other radioisotopes (121,122). Alternatively, fission—fragment track detection can detect Pu at a level of 10 g/g sample or better (123). Chemical concentration of Pu from urine, neutron irradiation in a research reactor, followed by fission track detection, can achieve a sensitivity for Pu of better than 1 mBq/L (4 X 10 g/g sample) (124). 

NAA is well suited for Si semiconductor impurities analysis. The sensitivity and the bulk mode of analysis make this an important tool for controlling trace impurities during crystal growth or fer monitoring cleanliness of various processing operations for device manufacturing. It is expected that research reactors will ser e as the central analytical facilities for NAA in the industry. Since reactors are already set up to handle radioactive materials and waste, this makes an attractive choice over installing individual facilities in industries. 

HFBR - High Flux Beam Reactor, a research reactor at BNL. 

Ring-shaped nuclear fusion research reactor Tokamak 15 at the Kurchatov Institute, Moscow, Russia. (Photo Researohers Ino.)... 

HM Nuclear Installations Inspectorate On HSE s behalf licenses nuclear installations ranging from nuclear power stations and chemical works to research reactors. 

In addition to fuel and targets(15J6) from SRP reactors, SRP also reprocesses a wide variety of fuels from offsite research reactors and a wide range of unirradiated plutonium scrap materials.(17) Following customary Savannah River practice, initial processing of each offsite material is designed to transform the actinides to a solution that is compatible with one of the solvent extraction cycles in either of the separations areas. A major advantage of this practice is that the... 

Figure 5.38 Routes to uranium mill concentrate processing to power /research reactor fuel products.

NAA is a mature field. The principles are well understood. No dramatic improvements are expected in either instrumentation or methodology that would revolutionise the method. However, access to a nuclear reactor is becoming a serious concern, in view of the ageing and shutdown of many research reactors. 

A permanent geologic repository is also important to our non-proliferation goals an alternative to reprocessing. . . storage for foreign research reactor fuel. . . and an option for the disposition of surplus plutonium from nuclear weapon stockpiles. 

The CHF in vertical upward and downward, countercurrent flow was recently studied by Sudo et al. (1991) in a vertical rectangular channel. Sudo and Kaminaga (1993) later presented a new CHF correlation scheme for vertical rectangular channels heated from both sides in a nuclear research reactor. 

Yoshihara K (1991) Workshop on Current Topics in the Behavior of Technetium (KURRI-TR-362) Research Reactor Institute Kyoto University, Kumatori, Osaka, Japan, p 42... 

The authors would like to thank Dr. Michael J. Welch of Washington University in St. Louis, USA and Dr. Gary J. Ehrhardt of the University of Missouri Research Reactor, University of Missouri-Columbia, USA for excellent technical assistance in the compilation of Table 1. 

Wiggins et al. [456] used neutrons from the thermal column of a 10 kW pool-type research reactor and from a 120 pg Cf source to study the prompt photon emission resulting from neutron capture in magnesium nodules (ter-romanganese oxides) from the ocean floor. Spectra were recorded with a Ce(Ii) detector and a 1024-channel analyser. Complex spectra were obtained by irradiation of seawater, but it was possible to detect and estimate manganese in nodules in a simulated marine environment by means of the peaks at 7.00, 6.55, 6.22, and 6.04 pV. 

As neutrons from research reactors or spallation sources are brought to an equilibrium temperature by collisions with a moderator, the temperature T in Eq. 

By contrast, the metals have so far found only limited application save for one important use in the field of nondestructive testing. With the proliferation of research reactors over the past decade, neutron radiography has become a practical tool in the aerospace, nuclear and engineering industries, yet without the availability of gadolinium and dysprosium in the form of thin foils, the technique would be severely restricted. 

Rb, and 865, The actinides and most of the other isotopes were made at the High Flux Research Reactor at Oak Ridge National Laboratory. The i3 +Cs, Rb, and isotopes were ob-... 

Center for Radiological Research and Missouri University Research Reactor, University of Missouri, Columbia, MO 65203. 

H. Yoshida and K. Hayashi Research Reactor Institute, Kyoto University, Osaka, and Department of Engineering, Hokkaido University, Sapporo, Japan... 

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