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Topic: Control rod

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	Control rod - Encyclopedia, History, Geography and Biography (Site not responding. Last check: 2007-09-07)
		A control rod is removed from or inserted into the central core of a nuclear reactor in order to control the neutron flux - increase or decrease the number of neutrons which will split further uranium atoms.
		Control rods stand vertically within holes through the pile, and are lifted partially out to allow a chain reaction to occur.
		Control rods are commonly composed of silver, indium and cadmium.
	www.arikah.net /encyclopedia/Nuclear_control_rod (385 words)

	[No title] (Site not responding. Last check: 2007-09-07)
		The control rod according to the invention leads to the power reduction for fuel pellets located adjacent to the upper part of the control rod becoming smaller in relation to fuel pellets which are not controlled with respect to fission velocity with the aid of control rods.
		In a control rod according to the invention, each one of the absorber blades comprises an upper and a lower part, the mean value of the contents of absorber material per unit of length of the control rod being smaller in the upper part of the control rod than in the lower part thereof.
		A control rod according to claim 9, characterized in that the channels (23,24) arranged nearest the cruciform centre (10) and the channels (22) arranged in the outer part of the absorber blades (6,7,8,9), arranged radially outside said cruciform centre, have a diameter (d) of essentially equal size.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=00/39808.000706&ELEMENT_SET=DECL (3478 words)

	Control rod (Site not responding. Last check: 2007-09-07)
		The control rod is inserted through the bottom of the reactor tank and glides up and down in the water gap between four adjacent fuel elements.
		The slow movement of the control rod regulating the output is implemented by means of electromechanical pinions.
		In Russian reactors (both RBMK and VVER) the effect of the control rods is increased by combining an absorber rod with a fuel element, which means that insertion/withdrawal implies simultaneous insertion/withdrawal of a fuel element.
	www.kose.ee /nucbasic/nucpedia/uk/control.htm (278 words)

	TRIGA® Products
		The TRIGA® Control Rod Drive for research reactors is an electrically driven linear drive mechanism to position and control movement of the reactor control rods and control blades.
		The upper portion of this barrel is ventilated to permit unrestricted rod movement in water, whereas the lower portion has graded vent holes to restrict movement and to provide a damping action when the electromagnet is deenergized and the control rod is released from the drive.
		Rod up/down motion is controlled from the control console, by energizing the magnet and stepping motor, which rotates the pinion gear shaft in turn raising the magnet draw tube.
	triga.ga.com /control_rod.html (355 words)

	Experiment_2 (Site not responding. Last check: 2007-09-07)
		Calibration of control rod (determination of reactivity worth per unit movement of control rod) is thus essential when the control rods are used as reactivity standards to measure the reactivity changes caused by any other perturbation in a reactor.
		Control rod calibration data is also important for the reactor operation; with control rod calibration data, the operator can estimate the reactivity caused by control rod movement and will be able to operate the reactor safety.
		The rod-drop method is to measure the subcriticality.; the rod to be calibrated is dropped from a certain position at the critical state, and the resulting decay of the neutron flux is observed and related to reactivity.
	www.rri.kyoto-u.ac.jp /CAD/english/experiment_2.htm (308 words)

	Control Rod Drive Characteristics.
		The predominant control rod is withdrawn from the core by means of a metal tape which is wound on a drum (4).
		The position of the control rod is indicated on a dial for manual inspection or a selsyn indicator (5) which is connected to the rod via a reducer.
		In case of an automatic scram the rod is in free fall for 5 s, the induction coil is reactivated in 5 s and dynamic braking is established to cushion the final segment of rod travel.
	www.insc.anl.gov /rbmk/reactor/control_rod.html (791 words)

	Method for removing control rod drive using tool to verify control rod drive uncoupling - Patent 5513229 (Site not responding. Last check: 2007-09-07)
		Control rod drives (CRDs) are used to position control rods in boiling water reactors (BWRs) to control the fission rate and fission density, and to provide adequate excess negative reactivity to shutdown the reactor from any normal operating or accident condition at the most reactive time in core life.
		A locking mechanism in the CRD permits the control rod to be positioned at 6-inch (152.4-mm) increments of stroke and to be held in these latched positions until the CRD is actuated for movement to a new position.
		For control rod withdrawal, a brief insert signal is applied to move index tube 26 upward to relieve the axial load on collet fingers 29a, camming them outward against the sloping lower surface of index tube locking notch 55.
	www.freepatentsonline.com /5513229.html (5290 words)

	Apparatus for exchanging control rod drive mechanism in a nuclear reactor - Patent 4288290
		The control rod drive mechanism 7 conveyed into the working chamber 1 is attached by bolts to a housing 10 of the control rod drive mechanism 7 in the reactor pressure vessel, and stud bolts 11 are suspended around this mechanism 7 and the housing 10.
		The movement of the control rod drive mechanism 7 to the inspection chamber, after the device 32 has been moved from the passage of movement of the carrier, is carried out in substantially the same manner as that described in connection with the first embodiment of this invention.
		In the aforementioned embodiments, although the control rod drive mechanism 7 is once held by the holding arm 33 during the lowering of the control rod drive mechanism 7, it may be possible to temporarily hold the control rod drive mechanism by the bolt mounting device conveying carriage.
	www.freepatentsonline.com /4288290.html (8287 words)

	United States Patent Application: 0040091077
		[0044] The control rod supporting structural body 2 is provided with a tie rod 4 having the cruciform cross section, a handle 5 fixed to an upper end of the tie rod 4 and a velocity limiter 6 fixed to a lower end of the tie rod 4.
		In this case, since the welding rod is irradiated with the YAG laser beam 23, heat generated by the irradiation is transferred from the welding rod (more precisely, a melted welding rod) to the sheath 8 to prevent the melt-down of the sheath 8, thereby achieving the good weldability.
		Also, since a thermal transfer from the sheath 8 to the drawn tie rod 12 is smaller due to the narrowed overlap L2, the possibility of the melt-down of the sheath 8, which results in a welding failure, is further increased in the conventional technique.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1="20040091077".PGNR.&OS=DN/20040091077&RS=DN/20040091077 (5255 words)

	[No title] (Site not responding. Last check: 2007-09-07)
		As a result, the pressure in the rod chambers of cylinders 12, 14 is controlled as a function of and is proportional to the pressure in the head chambers of cylinders 12,14.
		The control circuit of one of the claims 1 to 4, further comprising: a manually operated drain valve (64) which can be operated to communicate the rod and/or head chambers to sump.
		The control circuit of one of the claims 1 to 6, further comprising: an accumulator (26); and a suspension damping valve (28) for controlling communication between a chamber of the cylinder (12,14) and accumulator (26).
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=03/06270.030123&ELEMENT_SET=DECL (1792 words)

	Inanimate Carbon Rod - Wikipedia, the free encyclopedia
		The Inanimate Carbon Rod is a stick of carbon that appeared as a character in an episode of The Simpsons ("Deep Space Homer").
		Later in the episode, Homer was on the Space Shuttle with Race Banyon and Buzz Aldrin, and the door had to be closed in order for the shuttle to reenter the atmosphere.
		Upon return to earth, the population praised the rod, placing it on the cover of Time magazine ("In Rod We Trust"), and the carbon rod received its own ticker-tape parade.
	en.wikipedia.org /wiki/Inanimate_Carbon_Rod (233 words)

	Rod Control System Test Equipment (Site not responding. Last check: 2007-09-07)
		The rods are dropped by turning off the electrical power to one or more banks of rods while at the same time monitoring and recording their position indications.
		The disadvantage is that rod oscillation signals that are generated as a rod enters the dashpot cannot be identified.
		Prior to testing, the control computer and the EIB are placed close to the rod control power cabinets and the test points from the selected coils and slave cyclers are connected to the control computer through the EIB.
	www.ams-corp.com /equipment/rod_control_system_equip.html (1338 words)

	Corrugated thimble tube for controlling control rod descent in nuclear reactor - Patent 4229256
		The control rod is displaceable in a known controlled manner or by gravity between an upper position in which the absorbing portion is located outside the intense neutron flux zone of the reactor and a lower position in which the absorbing portion is located within the intense neutron flux zone of the reactor.
		For safety purposes, the control rods are also mounted in such a manner that all of them may be dropped simultaneously by gravity in order to effect an immediate shutdown of the reactor.
		The rod will slow down even more as it encounters the greater resistance to liquid displacement produced by the reduced diameter corrugations at points B and C. Generally, the corrugated portion of the tube 212 is a small fraction of its overall length.
	freepatentsonline.com /4229256.html (1694 words)

	Control Rod Location (Site not responding. Last check: 2007-09-07)
		Figure 10 clearly shows that the maximum control rod worth is found in the second large hexagonal block labeled 1,0 in Figure 2.
		The x axis is the large block position as shown in Figure 2 and the y axis is the difference in cents from the core without the control rod.
		The control rods were thus placed in the center of the large hexagonal fuel block 1,0.
	echelon1.mit.edu /~nate/research/bangstick/html/node28.html (77 words)

	World Nuclear Association \| Nuclear Industry Issues \| Chernobyl \| RBMK Control Rod Redesign (Site not responding. Last check: 2007-09-07)
		When the control rod is in its uppermost position, the rider is in the control rod cooling tube within the fuelled region of the core.
		When the reactor is "poisoned" with Xenon and with partially inserted control rods, the major part of the power is produced within the lower region of the core.
		This means that when the rod started to move down from its uppermost position, the rider removed water from the lower part, causing an increase in reactivity and hence in power.
	www.world-nuclear.org /info/chernobyl/rbmkrod.htm (268 words)

	Nuclear engineering other topics - control rod material
		Control rods come in all shapes, sizes and flavors to fit the needs and requirements of the different reactor designs.
		Cruciform control rod which looks more like a blade, and is made by (GE), who is the supplier of Boiling water reactors, these blades are inserted from the bottom of the reactor.
		Control rods for PWR are made in a cluster assembly, the cluster have about 15 rods in each fuel assembly.
	www.eng-tips.com /viewthread.cfm?qid=99164&page=1 (1056 words)

	Rod Movement Test Services (Site not responding. Last check: 2007-09-07)
		In response to the nuclear industry's need, AMS has developed a compliment of rod control system testing services for PWRs, including measurement of the drop times of the control and shutdown rods, measurement of the timing and sequencing of CRDMs, and slave cycler testing.
		The CRDM tests involve monitoring the stationary gripper current, movable gripper current, and lift coil current of a group of control and shutdown rods as they are moved in and out of the reactor.
		The test is performed by connecting the test equipment to the applicable test points while plant operations personnel initiate a request for rod withdrawal for a group or bank of rods (depending on the number of slave cyclers being tested concurrently) that were controlled by the selected slave cycler(s).
	www.ams-corp.com /services/rod_drop.html (398 words)

	Control rod drive endcap tool - Patent 5253407
		A conventional boiling water reactor includes a plurality of control rod drives (CRDs) mounted to a reactor pressure vessel, each of which includes an output rod extending therefrom for selectively inserting and withdrawing conventional control rods into and out of a conventional reactor core for controlling reactivity thereof.
		A plurality of conventional control rod drives (CRDs) 16, only three exemplary ones thereof being illustrated, are conventionally mounted to the lower head of the pressure vessel 12.
		The CRDs 16 are conventionally operated for either inserting into the core 14 or withdrawing from the core 14 the control rods 20 for selectively controlling reactivity of the core 14.
	freepatentsonline.com /5253407.html (3786 words)

	Marine propulsion device including an improved shift control rod - Patent 4258642
		Vertical movement of the shift control rod 50 causes pivotal movement of the bell crank 40 and consequent linear movement of the clutch dog 34 on the propeller shaft 26 to an intermediate neutral position or to selective engagement with one of the bevel gears 30 and 32.
		To facilitate construction of the outboard motor 10, the shift control rod 50 is comprised of two separate sections or portions, an upper shift control rod portion 64 and a lower shift control rod portion 66 fixedly joined together by a connector or coupling means 63 (FIG.
		The coupling 68 also includes a collar 86 surrounding the upper control rod 64 and including an externally threaded lower end 88 which can be threadably received in the threaded bore 72 of the lower shift rod 66.
	www.freepatentsonline.com /4258642.html (1468 words)

	Welcome To USSDevilfish.com, Cyberspace Home Of National Bestselling Submarine Fiction Author Michael DiMercurio
		Lower left on the vertical section are the control rod bottom lights, which show if a rod has dropped or if a group scram or full scram has happened, where scram is the term describing a reactor trip where the neutron-absorbing hafnium control rods shut down the nuclear fission reactions and shut down the plant.
		Scram stands for "safety control rod ax man," the ancient term for the way a carbon moderated lab reactor was shut down in the old days when Fermi had first put a reactor together.
		This plant's control rods were slammed into the reactor vessel by springs when the rod drives were disconnected by the scram switch.
	www.ussdevilfish.com /images/gall37.htm (544 words)

	CONTROL ROD/REG BLADE CALIBRATION (Site not responding. Last check: 2007-09-07)
		Control rods move neutron absorbing material into, and out of, the core region, changing the configuration from one mode to the other.
		We are interested in evaluating the effect of the control rods on the multiplication of the core when in a subcritical mode.
		With the core in a shutdown condition, withdrawing a blade (control or regulating) removes neutron absorbing material from the core.
	www.me.wpi.edu /Nuclear/Reactor/Labs/L-rodcal.html (685 words)

	Model Aviation's Frequently Asked Questions (Site not responding. Last check: 2007-09-07)
		You can increase control throw up to 125% of the normal maximum and you can reduce the control practically down to zero or no control on the other end so your servo travel can be easily adjusted electronically.
		If your control movement is too much and you want to reduce it, move the control rod on the servo output arm in closer to the center hub.
		In this situation, keep the control rod in the outermost hole of the servo output arm but begin to move inside on the control horn, closer to the actual control surface.
	www.modelaircraft.org /mag/FAQ/answers/faq-q28.htm (595 words)

	Flutter
		control rod coming out of the servo output arm is too far from the center of the servo thereby reducing any leverage.
		control rod is installed too close to the surface of the aileron, again eliminating the leverage that should exist.
		Position your control rod in the closest hole to the center of the servo control arm as possible.
	www.giantscaleplanes.com /flutter.htm (487 words)

	FRONTLINE: nuclear reaction: fission and reprocessing
		The key to generating a steady output of energy is controlling the nuclear fission inside a reactor core.
		The rods are made of a substance that readily absorbs neutrons, like graphite or cadmium.
		When control rods are lifted from the fuel assembly, neutrons (from the natural decay of uranium) bounce around and bombard other uranium atoms, causing them to split.
	www.pbs.org /wgbh/pages/frontline/shows/reaction/interact/getclose.html (208 words)

	Water Leakage from Penetration Portion of Control Rod Derive Housing into Reactor Pressure Vessel of Unit-1
		Furthermore, in the Units-2, 3 and 4, it was decided to use an improved leakage monitoring method in the containment and to improve the leakage monitoring in the containment by installing the measurement points of dew point temperature in the lower part of the reactor pressure vessel.
		Regarding leakage from the control rod drive housing portion in the Hamaoka Unit-1, boat sample taken from the lower weld portion of the stub tube, where cracks were recognized, and metal investigation was performed.
		Regarding leakage from the control rod drive housing portion (weld portion of the lower part of the stub tube), which was found on November 9, 2001, Chubu Electric Power Company investigated the cause and examined the countermeasures.
	www2.jnes.go.jp /atom-db/en/trouble/individ/power/j/j01b121/news.html (2760 words)

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