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Topic: Subcritical

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	Subcritical reactor - Wikipedia, the free encyclopedia
		subcritical reactor is a nuclear fission reactor that produces fission without achieving criticality.
		Subcritical reactors have been proposed both as a means of generating electric power and as a means of transmutation of nuclear waste, so the gain is twofold.
		However, the solution of a subcritical reactor might be favoured for a better public acceptance—it is considered more acceptable to burn the waste than to bury it for hundreds of thousands of years.
	en.wikipedia.org /wiki/Subcritical_reactor (734 words)

	Security: Subcritical Nuclear Weapons Experiments
		Subcritical nuclear experiments differ from traditional nuclear weapons tests in that they are designed to not reach criticality, in other words to not sustain a nuclear chain reaction.
		The subcriticals are one component of the "Stockpile Stewardship" program, a $60 billion (over 13 years) program initiated by the U.S. Department of Energy to upgrade old nuclear weapons facilities and build new ones for the purpose of maintaining the "safety" and Areliability" of the enduring nuclear stockpile in the absence of underground nuclear testing.
		Because subcritical experiments are setting a new and destabilizing precedent that other nations might choose to emulate, it is in the U.S. national security interest to ensure that any such verification plan can be applied to other states that might be capable of conducting low-yield nuclear weapons experiments.
	www.psr.org /home.cfm?id=subcritical (1565 words)

	Supercritical and Subcritical Extraction Technologies Center
		The EERC is a world leader in understanding the chemistry of water and CO under pressurized and heated (supercritical and subcritical) conditions for the extraction and separation of organic compounds that are not efficiently extracted without the use of hazardous organic solvents.
		The development of subcritical water extraction as a replacement for hazardous and toxic solvents used for analytical extractions.
		Subcritical water can also be used to destroy reactive organic pollutants such as the explosives in many pesticides and PCBs.
	www.undeerc.org /centersofexcellence/extraction.asp (496 words)

	SUBCRITICAL NUCLEAR TEST
		Subcritical nuclear tests are a nuclear test that you have when you're not having a nuclear test.
		Antinuclear groups in the US and elsewhere argue that subcritical nuclear tests are not necessary for safety and that they allow the further development and optimisation of weapons design, by investigating the early stages of a full -scale nuclear explosion.
		A 'subcritical' nuclear test is a nuclear test that stops just milliseconds short of a full chain reaction, allowing detailed investigation into the critical first stages of a nuclear explosion.
	www.nuclear-free.com /english/doe.htm (769 words)

	SUBCRITICAL EXPERIMENTS
		While we will continue to label these experiments as subcritical, in keeping with accepted usage, we note that they are not weapons tests at all, but weapons-related physics tests in which the nuclear properties of plutonium play no role.
		The calculated configurations were found to be subcritical by a comfortably wide margin, and that was the end of the peer-review process.
		In the current state of the art, a direct criticality measurement is not impossible but is fraught with difficulty; it would require irradiation of the sample by a strong external neutron source during the experiment.
	www.fas.org /rlg/jsr97300.htm (2341 words)

	Subcritical Nuclear Weapons Tests
		Subcritical Tests were conducted on the surface while others were conducted underground in shafts, shallow boreholes or tunnels.
		Subcritical nuclear tests are a component of the U.S. Department of Energy's Science Based Stockpile Stewardship Management Program (SSMP) and are intended to show whether nuclear weapons components such as Plutonium and Uranium will develop problems as they age.
		Subcritical nuclear tests are a component of the U.S. Department of Energy's Stockpile Stewardship Management Program (SSMP) and are intended to show whether nuclear weapons components such as Plutonium and Uranium will develop problems as they age.
	www.shundahai.org /sub_crit.htm (895 words)

	Disposition of Nuclear Wastes Using Subcritical Accelerator-Driven Systems
		Subcritical systems do not rely on delayed neutrons for control and power change; they are driven only by the externally generated neutron source (i.e.
		Because of its subcritical mode of operation, ATW will be ideally suited as incinerator of material that is not well characterised, that transmutes very poorly or not at all in reactors, that has potentially unstable and hazardous reactivity responses, and that should not for whatever reason be isolated and placed in reactors.
		The cost of subcritical ATW transmuters based upon lead—bismuth coolant technology should be comparable or lower than the cost of critical sodium-cooled reactors, as evidenced by the Russian LBE-cooled reactor designs and experience.
	www.world-nuclear.org /sym/1999/venneri.htm (6903 words)

	[No title]
		Subcritical experiments examine the behavior of plutonium as it is strongly shocked by forces produced by chemical high explosives.
		Subcritical experiments produce essential scientific data and technical information used to help maintain the safety and reliability of the nuclear weapons stockpile.
		Since September 1998, at least 14 subcritical tests were blasted in the tunnels near the Matotchin Shar that divides the northern and southern island of Novaya Zemlya.
	www.atsnn.com /story/196400.html (2774 words)

	DECLARE A MORATORIUM ON SUBCRITICAL TESTING
		By contrast, should the US conduct a subcritical test at this tense moment in history, it would only serve to fuel the flames of nuclear frenzy in other nations.
		Subcritical testing, which includes site preparations that look almost identical to those of a full-scale nuclear test, also makes verification of the test ban more difficult.
		Taking a strong leadership approach and declaring a moratorium on the US subcritical testing program would send a much better and much safer message to India, Pakistan, and other nuclear aspirants: that the US is willing to step out on the path against nuclear testing and nuclear weapons.
	www.fas.org /nuke/control/ctbt/news/980716-sub.htm (416 words)

	A Technology now being Deployed in Developing Countries
		Reviewing the possibilities for the design and manufacture of components for supercritical-fired plants in developing countries, the paper notes that the differences between subcritical and supercritical power plants are limited to a relatively small number of components; primarily the feedwater pumps and the high-pressure feedwater train equipment.
		While subcritical power plants using drum-type boilers are limited in their load change rate due to the boiler drum (a component requiring a very high wall thickness), supercritical power plants using once-through boilers can achieve quick load changes when the turbine is of suitable design.
		As discussed, the differences in the technology between subcritical and supercritical coal fired power plants are limited to small number of components.
	www.worldbank.org /html/fpd/em/supercritical/supercritical.htm (2469 words)

	Las Vegas SUN: Subcritical nuclear test scheduled in 2004
		Subcritical experiments involve exposing tiny amounts of nuclear materials to high explosives.
		Subcritical experiments allow scientists to study how plutonium and other radioactive materials behave when detonated with explosives.
		The subcritical experiments are designed to test the skills of U.S. nuclear weapons experts, as well as the materials contained in the U.S. nuclear arsenal.
	www.lasvegassun.com /sunbin/stories/lv-gov/2003/aug/25/515521789.html (302 words)

	CFPA - Subcritical=Hypocritical (Site not responding. Last check: 2007-10-03)
		Conducting subcritical experiments would likely harden the position of several states concerned that the US (and other declared weapons states) will continue nuclear weapons development through their "stockpile stewardship" programs such as subcritical experiments.
		Although the DOE claims that the subcriticals do not violate the "zero-yield" CTBT, it will be difficult for other countries to verify that the subcriticals do not actually achieve critically.
		DOE (Department of Energy) claims that subcriticals are needed to (1) improve knowledge of the dynamic properties of aged nuclear materials (like plutonium) and (2) to maintain the Nevada Test Site capabilities and readiness.
	www.peacecoalition.org /facts/subcritical-hypocritical.html (615 words)

	US conducts subcritical nuclear test. 24/02/2006. ABC News Online
		The US argues that subcritical tests are fully consistent with the nuclear test moratorium.
		The US argues that subcritical tests are fully consistent with the nuclear test moratorium it has maintained since 1992.
		According to the department, subcritical tests ''examine the behaviour of plutonium as it is strongly shocked by forces produced by chemical high explosives".
	www.abc.net.au /news/newsitems/200602/s1577409.htm (348 words)

	Information Bridge: DOE Scientific and Technical Information
		Subcritical source-driven noise measurements are simultaneous Rossi-{alpha} and randomly pulsed neutron measurements that provide measured quantities that can be related to the subcritical neutron multiplication factor.
		In fact, subcritical source-driven noise measurements should be performed in lieu of Rossi-{alpha} measurements because of the additional information that is obtained from noise measurements such as the spectral ratio and the coherence functions.
		The subcritical source-driven noise measurement has advantages over other subcritical measurement methods in that reference measurements at delayed critical are not required for interpreting the measurements.
	www.osti.gov /bridge/product.biblio.jsp?osti_id=814835 (355 words)

	CTBT Events and Campaigns (Site not responding. Last check: 2007-10-03)
		SUBCRITICAL EXPERIMENTS are scientific experiments to obtain technical information in support of the DOE program to maintain the safety and reliability of the U.S. nuclear weapons stockpile with nuclear testing.
		Conducting subcritical experiments would likely harden the position of several states concerned that the United States (and other declared weapons states) will continue nuclear weapons development through their "stockpile stewardship" programs such as subcritical experiments.
		Although the subcriticals do not technically violate the "zero-yield" CTBT, it will be difficult for other countries to verify that the subcriticals do not actually achieve criticality.
	disarm.igc.org /testing.html (2821 words)

	Subcritical Tests
		If the U.S. were to conduct the subcritical experiments, it would likely harden the position of several states who are concerned that the United States (and other declared weapons states) will continue nuclear weapons development through their laboratory-based, "stockpile stewardship" programs and activities such as subcritical experiments.
		Though the DOE claims that the subcritical experiments would be in conformance with the recently-signed "zero-yield" CTBT, these experiments would severely complicate the ability of the U.S. and other states to verify that the terms of the CTBT are not violated by any nation.
		Because U.S. subcritical experiments would set a new and destabilizing nuclear proliferation precedent that other nations might choose to emulate, it is in the United States national security interest to ensure that any such verification plan can be applied to other states that might be capable of conducting low-yield nuclear weapons experiments.
	www.prop1.org /2000/subcrit/update.htm (1345 words)

	SUBCRITICAL
		Subcritical multiplication is the phenomenon that accounts for the changes in neutron flux that takes place in a Subcritical reactor due to reactivity changes.
		It is important to understand Subcritical multiplication in order to understand reactor response to changes in conditions.
		In a subcritical reactor, the neutron level is related to the source strength by Equation (4-2).
	www.tpub.com /doenuclearphys/nuclearphysics77.htm (958 words)

	[No title]
		The first subcritical experiment is scheduled for June 1997 with a second experiment later this fall.
		Many arms control observers and diplomatic officials also believe that conducting the underground subcritical experiments would have a severe and negative impact on securing the formal entry-into-force of the CTBT, which requires the ratification of the Treaty by 44 named nuclear weapons-capable states.
		The Energy Department originally planned to begin conducting subcritical experiments in 1996, but they were forced to postpone the tests because of their potential negative impact on the Comprehensive Test Ban Treaty negotiations.
	nuclearweaponarchive.org /News/Subcrit2.txt (1106 words)

	Lab to conduct 'subcritical' experiment (Site not responding. Last check: 2007-10-03)
		Raffi Papazian, the lab's director of operations at the Nevada Test Site, said the first experiments were designed to answer basic scientific questions regarding the nature and behavior of plutonium, the radioactive metal at the core of a modern thermonuclear bomb.
		Subcritical tests help maintain expertise and equipment in case the United States decides to recommence testing, Papazian also said.
		By comparison, he said, an average underground nuclear test might run $70 million to $90 million, although the budget for some could be more than twice that amount.
	www.nukewatch.org /media2/postData.php?id=825 (810 words)

	Low Density Universes and Inflation
		A universe initially with slightly subcritical density rapidly becomes increasingly subcritical and soon virtually indistinguishable from an empty universe.
		However, a universe of subcritical or supercritical density has a non-Euclidean geometry---hyperbolic if the density is subcritical, or spherical if the density is supercritical.
		We present the so-called "cluster baryon fraction" as one illustrative example of the strong evidence in favor of a universe of subcritical density.
	www.damtp.cam.ac.uk /user/gr/public/inf_lowden.html (2586 words)

	Nuclear weapon - Facts, Information, and Encyclopedia Reference article
		A mass of fissile material is rapidly assembled into a critical mass, in which a chain reaction begins and grows exponentially, releasing tremendous amounts of energy.
		This is accomplished either by shooting one piece of subcritical material into another, or compressing a subcritical mass into a state of supercriticality.
		A major challenge in all nuclear weapon designs is ensuring that a significant fraction of the fuel is consumed before the weapon destroys itself.
	www.startsurfing.com /encyclopedia/n/u/c/Nuclear_weapon.html (2637 words)

	NucNews - September 29, 1999
		Subcritical nuclear tests involve blowing up high explosives along with fissile material such as plutonium 239.
		Performed underground in specially prepared rooms, subcritical tests are used as a to study what happens to the plutonium during the detonations.
		DOE also claims that, since subcritical tests do not rise to the level of self-staining chain reactions, they are not true nuclear tests and thus comply with the CTBT.
	nucnews.net /nucnews/1999nn/9909nn/990929nn.htm (20626 words)

	Future Energy Development Encyclopedia Articles @ LaunchBase.org (Launch Base) (Site not responding. Last check: 2007-10-03)
		Both nuclear reprocessing and fast breeder reactors can reduce the amounts of waste, but have currently unsolved problems of their own.
		It is argued that Subcritical reactors or fusion reactors could greatly reduce the time the waste has to be stored
		It is also argued that subcritical reactors may also be able to do the same to already existing waste, but they have yet to be developed.
	www.launchbase.org /encyclopedia/Future_energy_development (4828 words)

	Subcritical Software
		The April 13, 2006 data update for AeroFacsDisplay is now available from the Subcritical Online Store.
		The AeroFacsDisplay December 22 data update is now available for purchase from the Subcritical online store.
		I changed the colors to work with the new Subcritical logo designed by Jordan Langille at buyicons.com.
	www.subcritical.com (461 words)

	Subcritical Elliptic Bursting of Bautin Type (Site not responding. Last check: 2007-10-03)
		Bursting behavior in neurons is a recurrent transition between a quiescent state and repetitive spiking.
		When the transition to repetitive spiking occurs via a subcritical Andronov-Hopf bifurcation and the transition to the quiescent state occurs via double limit cycle bifurcation, the burster is said to be of subcritical elliptic type.
		When the fast subsystem is near a Bautin (generalized Hopf) point, both bifurcations occur for nearby values of the slow variable, and the repetitive spiking has small amplitude.
	www.nsi.edu /users/izhikevich/publications/subEB.htm (272 words)

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