Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C17/00—Monitoring; Testing ; Maintaining
  • G21C17/06—Devices or arrangements for monitoring or testing fuel or fuel elements outside the reactor core, e.g. for burn-up, for contamination
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin
  • Y02E30/30—Nuclear fission reactors

Definitions

• the subject of this invention is a nuclear fuel rod control method.
• Some nuclear fuel rods include a cladding containing a stack of fuel pellets and closed at an open end by a plug which is then welded. A spring is compressed between the stopper and the stack of pellets to hold the latter in place.
• Non-destructive checks are carried out to verify certain characters of the assembled pencil.
• an electromagnetic detector is used to check the presence of the spring and the length of the chamber which contains it between the cap and the pellets of " fuel.
• the process in question here uses a measurement of this kind to determine, according to an unpublished reasoning, the quality of the welding of the plug. It has indeed been noted that the. weld quality was highly dependent on the energy supplied. If excessive, droplets of molten metal can settle on the spring and affect its condition or stick to the cap. One should particularly fear the modification of the metallurgical structure of the spring, the sheath and the plug by excessive heating. A pencil with a damaged spring must be rejected, just like a pencil with an absent spring.
• the invention relates to a method for controlling a nuclear fuel rod with an extreme plug welded to a sheath, a coil spring being compressed between the plug and the fuel, by an electromagnetic induction detector along from which the pencil is moved, by measuring an " output signal from the detector, characterized in that it consists in taking a value of the signal at a base portion, obtained next to the pencil in 1 '' absence of coupling magnetic with the pencil, and " another signal value and at a peak adjacent to the base portion, where the plug and one end of the spring adjacent to the plug exert maximum magnetic coupling, calculating a ratio of the signal values and to accept or reject the pencil depending on whether the ratio is above or below a threshold.
• FIG. 1 is a general view of the apparatus used for implementing the method
• FIG. 1 there is shown a pencil 1 of nuclear fuel, the sheath of which bears the reference 2, the upper cap the reference 3, the pellets stacked with the reference 4, and the spring the reference 5.
• ⁇ -understand 530 turns of copper wire of a tenth of a millimeter in diameter.
• the primary winding 12 is
• the secondary winding 13 is traversed by an induced current, the voltage of which depends on the magnetic coupling produced by the pencil 1. In fact, the pencil 1 is moved along the detector 9 passing through the recess 11, giving
• the abscissas express a scroll length and the ordinates a voltage measured by the secondary winding 13.
• a constant or basic value is recorded corresponding to an absence of magnetic influence of the pencil 1, or to an empty test, and whose value SI is 2.6 volts approximately in the present example.
• the value of the signal suddenly increases when the magnetic coupling produced mainly by the end 7 of the spring 5 is felt, up to a peak value S4 of between approximately 4.0 and 4.5 volts in this example. Then, the magnetic coupling is produced mainly by the central portion of the spring 5, so that the signal takes a lower plateau value S3, of approximately 3.3 or 3.4 volts.
• the signal When the magnetic coupling is "produced mainly by the other end 8 of the spring 5, the signal returns appreciably to a high value of peak S5-which is in practice close to S4, or sometimes. A little higher. -Finally, -if we continue to move the pencil 1 through, - the detector 9, the signal takes a stable value ⁇ ' 2, the coupling being produced essentially by the sheath 2, and whose value is a little - ⁇ - to Sl ...
• the process according to the invention consists in reading the values S4, S5 and S3 and making the
• S3 a threshold, which can be -10% in the example considered but must be determined empirically in others, and to judge that the pencils 1 comply with the manufacturing requirements if this ratio is greater or less than the threshold (in the example, less than the threshold).
• This curve also makes it possible to determine the compressed length of the spring 5 or of the chamber which contains it, by measuring the distance between the two peaks, and the very presence of the spring 5, because no peak is observed if it is absent and the measurement curve goes from the SI value to the S2 value directly.
• S4 and S5 do not only depend on the magnetic coupling of the rod 1 at the location sensitive to manufacturing defects, but also on environmental characteristics, the length of the spring and the detector itself. It is therefore safer to weight these values " ... SA and. S5 by the plateau value S3 which offers a kind of,. - reference signal.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Monitoring And Testing Of Nuclear Reactors (AREA)
• Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
• Butt Welding And Welding Of Specific Article (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (9)

Families Citing this family (5)

Citations (2)

Family Cites Families (6)

• 2002
  • 2002-02-08 FR FR0201557A patent/FR2835957B1/fr not_active Expired - Lifetime
• 2003
  • 2003-02-06 AU AU2003222361A patent/AU2003222361A1/en not_active Abandoned
  • 2003-02-06 CN CNB038035219A patent/CN1282199C/zh not_active Expired - Lifetime
  • 2003-02-06 US US10/502,874 patent/US20050105669A1/en not_active Abandoned
  • 2003-02-06 DE DE60333727T patent/DE60333727D1/de not_active Expired - Lifetime
  • 2003-02-06 RU RU2004126952/06A patent/RU2303302C2/ru not_active IP Right Cessation
  • 2003-02-06 JP JP2003566862A patent/JP4177265B2/ja not_active Expired - Fee Related
  • 2003-02-06 EP EP03717377A patent/EP1472701B1/fr not_active Expired - Lifetime
  • 2003-02-06 WO PCT/FR2003/000375 patent/WO2003067607A2/fr not_active Ceased

Patent Citations (2)

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