control rod

(noun)

any of a number of steel tubes, containing boron or another neutron absorber, that is inserted into the core of a nuclear reactor in order to control its rate of reaction

Related Terms

Examples of control rod in the following topics:

  • Nuclear Fission in Reactors

    • A nuclear chain reaction can be controlled by using neutron poisons and neutron moderators to change the percentage of neutrons that will go on to cause more fissions.
    • The power output of the reactor is adjusted by controlling how many neutrons are able to create more fissions.
    • Control rods that are made of a neutron poison are used to absorb neutrons.
    • Absorbing more neutrons in a control rod means that there are fewer neutrons available to cause fission, so pushing the control rod deeper into the reactor will reduce the reactor's power output, and extracting the control rod will increase it.

  • MreB and Determinants of Cell Morphology

    • Indeed, recent studies have found that MreB proteins polymerize to form filaments that are similar to actin microfilaments.MreB controls the width of rod-shaped bacteria, such as Escherichia coli.
    • A mutant E. coli that creates defective MreB proteins will be spherical instead of rod-like.
    • This ability of MreB is because of RodZ, an inner membrane protein containing an 80-residue, N-terminal cytoplasmic region, and a 200-amino acid periplasmic C-terminal tail.
    • RodZ co-localizes with MreB helices in a manner that is strictly dependent on its cytoplasmic region.
    • MreB- RodZ complexes act as a major stabilizing factor in bacterial cell wall and ensure the insertion of new peptidoglycan in a spiral like fashion into the cell wall.

  • Vision: The Visual System, the Eye, and Color Vision

    • the retina, which allows us to piece images together and includes cones and rods.
    • The left hemisphere of the brain controls the motor functions of the right half of the body, and vice versa; the same is true of vision.
    • Generally speaking, cones are for color vision and rods are for shadows and light differences.
    • This density map shows the retina, which is made up of cones and rods.
    • Cones perceive color and rods perceive shadow in images.

  • Mechanical Work and Electrical Energy

    • where B is the magnetic field, l is the length of the conducting rod, and v is the (constant) speed of its motion.
    • As the rod moves and carries current i, it will feel the Lorentz force
    • To keep the rod moving at a constant speed v, we must constantly apply an external force Fext (equal to magnitude of FL and opposite in its direction) to the rod along its motion.
    • Since the rod is moving at v, the power P delivered by the external force would be:
    • Right hand rule gives the current direction shown, and the polarity of the rod will drive such a current.

  • Motional EMF

    • Consider the area enclosed by the moving rod, rails and resistor.
    • B is perpendicular to this area, and the area is increasing as the rod moves.
    • Thus the magnetic flux enclosed by the rails, rod and resistor is increasing.
    • Note that the area swept out by the rod is ΔA=ℓx.
    • Right hand rule gives the current direction shown, and the polarity of the rod will drive such a current.

  • Transduction of Light

    • Light is tranduced in rods and cones; visual information is processed in the retina before entering the brain.
    • The rods and cones are the site of transduction of light into a neural signal.
    • Visual signals leave the cones and rods, travel to the bipolar cells, and then to ganglion cells.
    • In the absence of light, the bipolar neurons that connect rods and cones to ganglion cells are continuously and actively inhibited by the rods and cones.
    • Human rod cells and the different types of cone cells each have an optimal wavelength.

  • The Physical Pendulum

    • Recall that a simple pendulum consists of a mass suspended from a massless string or rod on a frictionless pivot.
    • In that case, we are able to neglect any effect from the string or rod itself.
    • For illustration, let us consider a uniform rigid rod, pivoted from a frame as shown (see ).
    • The moment of inertia of the rigid rod about its center is:
    • A rigid rod with uniform mass distribution hangs from a pivot point.

  • Pathogenic Escherichia coli

    • In 2006, Fort Dodge Animal Health (Wyeth) introduced an effective, live, attenuated vaccine to control airsacculitis and peritonitis in chickens.
    • Escherichia coli (E. coli) is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms).
    • In stool samples, microscopy will show Gram-negative rods, with no particular cell arrangement.

  • Arboviral Encephalitis

    • The majority of the arboviruses are spherical in shape although a few are rod-shaped.
    • Vector control measures, such as habitat control (including the elimination of stagnant water and the spraying of insecticides), are essential to reducing the transmission of disease by arboviruses.

  • Sporulation in Bacillus

    • Bacillus subtilis is a rod-shaped, Gram-postive bacteria that is naturally found in soil and vegetation.
    • In short, initiation of sporulation is a very tightly regulated network with numerous checkpoints for efficient control.
    • Several additional proteins participate, mainly by controlling the accumulated concentration of Spo0A~P.