Patent Number: 047626712
Section: claims

1. In a nuclear reactor pressure vessel having a cylindrical side wall with an interior surface, at least one nozzle penetrating said side wall, piping penetrating said side wall at said nozzle, said nozzle and said piping forming an annular gap at said interior surface of said side wall, and means for decontaminating said reactor pressure vessel at said annular gap, said means for decontaminating comprising: a casing;  means for suspending said casing in the reactor pressure vessel from a position above the reactor pressure vessel, whereby said casing can be positioned adjacent to the gap;  at least one injection nozzle arranged at a positive dip angle in said casing  means for supplying high-pressure liquid to said at least one injection nozzle;  means mounted on said casing for detecting that said at least one injection nozzle is positioned such that high-pressure liquid therefrom may be injected into the gap; and  means for selectively fixing said casing to the reactor pressure vessel when said detecting means detects that said at least one injection nozzle is positioned such that high-pressure liquid therefrom may be injected into the gap.  a casting;  means for suspending said casing in the reactor pressure vessel from a position above the reactor pressure vessel, whereby said casing can be positioned adjacent to the gap;  at least one injection nozzle arranged in said casing;  means for supplying high-pressure liquid to said at least one injection nozzle;  means mounted on said casing for detecting that said at least one injection nozzle is positioned such that high-pressure liquid therefrom may be injected into the gap; and  means for selectively fixing said casing to the reactor pressure vessel when said detecting means detects that said at least one injection nozzle is positioned such that high-pressure liquid therefrom may be injected into the gap, said fixing means comprising at least one electromagnet fixed to said casing.  a casing;  means for suspending said casing in the reactor vessel from a position above the reactor pressure vessel, whereby said casing can be positioned adjacent to the gap;  at least one injection nozzle arranged in said casing;  means mounted on said casing for supplying high-pressure liquid to said at least one injection nozzle;  means for detecting that said at least one injection nozzle is positioned such that high-pressure liquid therefrom may be injected into the gap, said detecting means comprising at least one tough sensor; and  means for selectively fixing said casing to the reactor pressure vessel when said detecting means detect that said at least one injection nozzle is positioned such that high-pressure liquid therefrom may be injected into the gap. 2. Means for decontaminating according to claim 1, wherein said at least one injection nozzle is formed as a slit elongated along said gap. 3. Means for decontaminating according to claim 1, wherein said dip angle is between 0.degree. and 45.degree.. 4. Means for decontaminating according to claim 1, wherein said means for selectively fixing comprises at least one electromagnet fixed to said casing. 5. Means for decontaminating according to claim 1, wherein said means for detecting comprises at least one touch sensor. 6. Means for decontaminating according to claim 1, wherein said casing includes a vertically extending groove extending over the entirety of a surface of said casing, whereby said casing can avoid interferring with an obstacle projecting from the reactor pressure vessel side wall. 7. Means for decontaminating according to claim 1, wherein said means for supplying high-pressure liquid comprises means for supplying at least 0.2 m.sup.3 /hr of said high-pressure liquid. 8. Means for decomtaminating according to claim 1, wherein said at least one injection nozzle is positioned on said casing so as to be spaced from a vertical plane passing through an axis of the reactor pressure vessel by an arcuate angle of no more than 7.5.degree. when said at least one injection nozzle is positioned such that high-pressure liquid therefrom may be injected into the gap. 9. Means for decontaminating according to claim 1, comprising at least two of said injection nozzles and further comprising means for selectively supplying high pressure liquid to only one of said nozzles at a time. 10. Means for decontaminating according to claim 4, in combination with a reactor pressure vessel having a low alloy steel matrix with a 5 mm thick internal lining of austenitic stainless steel, wherein each said at least one electromagnet has an electromagnetic coil with a diameter of between 80 mm and 90 mm. 11. In a nuclear reactor pressure vessel having a cylindrical side wall with an interior surface, at least one nozzle penetrating said side wall, piping penetrating said side wall at said nozzle, said nozzle and said piping forming an annular gap at said interior surface of said side wall, and means for decontaminating said reactor pressure vessel at said annular gap, said means for decontaminating comprising: 12. Means for decontaminating according to claim 11, wherein said at least one injection nozzle is formed as a slit elongated along said gap. 13. Means for decontaminating according to claim 11, wherein said means for detecting comprises at least one touch sensor. 14. Means for decontaminating according to claim 11, wherein said casing includes a vertically extending groove extending over the entirety of a surface of said casing, whereby said casing can avoid interferring with an obstacle projecting from the reactor pressure vessel side wall. 15. In a nuclear reactor pressure vessel having a cylindrical side wall with an interior surface, at least one nozzle penetrating said side wall, piping penetrating said side wall at said nozzle, said nozzle and said piping forming an annular gap at said interior surface of said side wall, and means for decontaminating said nuclear reactor vessel at said annular gap, said means for decontaminating comprising: 16. Means for decontaminating according to claim 15, wherein said at least one injection nozzle is formed as a slit elongated along said gap. 17. Means for decontaminating according to claim 15, wherein said casing includes a vertically extending groove extending over the entirety of a surface of said casing, whereby said casing can avoid interferring with an obstacle projecting from the reactor pressure vessel side wall.