Patent Number: 
Section: claims

1. A method for monitoring the confinement of an enclosure, said enclosure comprising walls delimiting an interior volume and exterior surroundings outside said enclosure, whereby a differential pressure (ΔP) is continuously maintained between the interior volume of the enclosure and said exterior surroundings, the method comprisingwith the enclosure comprising an orifice in one of its walls establishing fluidic communication between said interior volume and said exterior surroundings, said orifice has passing through it a flow of gas at a speed (V) at least equal to a reference speed Vref under the effect of said differential pressure (ΔP), according to which method the following steps are carried out:the speed (V) of said gas flow is measured at predetermined time intervals or continuously and this speed measurement (V) is compared with the reference speed Vreference,when the speed measurement (V) is lower than the reference speed Vreference, at least one alarm signal is emitted. 2. The method as claimed in claim 1, wherein said differential pressure (ΔP) between the interior volume of the enclosure and said exterior surroundings is established by at least one ventilation system. 3. The method as claimed in claim 2, wherein, having determined a reference flow rate (Qref) at which said enclosure is ventilated by said at least one ventilation system, the following steps are carried out:the flow rate (Q) at which said enclosure is ventilated is measured,the ventilation flow rate measurement (Q) thus obtained is compared with the reference flow rate (Qref) to determine whether the ventilation flow rate has dropped, andif appropriate, the ventilation flow rate (Q) is adjusted to generate a gas flow passing through said orifice at a speed at least equal to said reference speed Vreference. 4. The method as claimed in claim 3, wherein, with the ventilation flow rate (Q) of said enclosure being equal or substantially equal to the reference flow rate (Qref), the leak or leaks in said enclosure is or are located and said leak or leaks is or are plugged. 5. The method as claimed in claim 2, wherein said at least one ventilation system is chosen from the group comprising:a gas flow extraction system,a gas flow inlet system, a reversible system capable of switching between a gas flow extraction mode anda gas flow inlet mode and combinations of these elements. 6. The method as claimed in claim 1, wherein said differential pressure (ΔP) between the interior volume of the enclosure and said exterior surroundings is established by at least one gas flow supply source that has an inlet flow rate (Q). 7. The method as claimed in claim 1, wherein the following steps are performed beforehand in order to determine said value Vreference for the reference speed of the gas flow:a tracer gas is introduced into said enclosure,the presence and concentration of said tracer gas outside said enclosure are detected and measured using one or more pieces of analysis equipment for various values for the speed of the gas flow entering through said fixed-diameter orifice and under various operating conditions of said enclosure,the data thus obtained are compared and the smallest of said speed values for which the detected concentration of said tracer gas outside said enclosure under the various envisioned operating conditions is below or equal to a threshold value is retained. 8. The method as claimed in claim 1, wherein said incoming gas flow is air or neutral gas. 9. The method as claimed in claim 1, wherein said reference speed Vreference is at least equal to 1 m·s−1. 10. The method as claimed in claim 9, wherein said reference speed Vreference is strictly equal to 1 m·s−1. 11. A device for implementing the method for monitoring the confinement of an enclosure as claimed in claim 1, the device comprises at least:a pipe of diameter D intended to be mounted on an orifice of a wall of said enclosure, said pipe comprising a nonreturn valve which closes off said pipe to prevent the passage of a flow of gas from inside the enclosure toward the exterior surroundings when said enclosure is at a reduced pressure with respect to the exterior surroundings, or from the exterior surroundings toward the interior volume of said enclosure when said enclosure is at a raised pressure with respect to the exterior surroundings, anda means of measuring the speed of the gas flow passing along said pipe. 12. The device as claimed in claim 11, wherein said means of measuring speed is an anemometer. 13. The device as claimed in claim 11 wherein it additionally comprises an audible and/or luminous alarm for emitting at least one alarm signal when the speed (V) measured by the speed measuring means is below a threshold speed value. 14. A confinement enclosure comprising at least one interior volume delimited by walls and at least one device for placing this interior volume of said enclosure at a reduced pressure or at a raised pressure in relation to the exterior surroundings in which said enclosure is placed, wherein it comprises a device for implementing the monitoring method as claimed in claim 11, this device being mounted on an orifice of one of said walls of the enclosure delimiting said interior volume. 15. The enclosure as claimed in claim 14, further comprising a flow meter for measuring the extraction flow rate of said device for creating the reduced pressure, or the inlet flow rate of said device for creating a raised pressure, this flow meter comprising an anemometer or a Pitot tube for measuring the extraction or admission speed respectively, said anemometer or said Pitot tube being connected to a processing unit for calculating the extraction or admission flow rate from the extraction or admission speed thus measured, respectively.