| 摘要 |
A tubular instrument channel for a nuclear reactor is sealed by sealing the 1st open end of the thimble (14) and fixing into the thimble extension, an extension tube (20) having a cross section less than the cross section of the instrument channel. By pushing the extension tube (20), the thimble (14) is moved along the axial direction of the instrument channel towards the end that leads to the reactor vessel until the 1st end of the thimble is beyond a closing mechanism or tight penetration device of the thimble. The annular clearance between the extension tube and the internal surface of the instrument tube is then closed and sealed up. Also claimed is a device for sealing an instrument channel of a PWR that consists of a spindle (21) having a threaded part at each end (29, 30), a smooth cylindrical body and a collar (31) between the 2 threaded ends and a groove (28) for a seal between the collar (31) and the 1st threaded part (29) which when screwed into the tapped end of the thimble (14) ensures a sealed joint between the collar (31) and the 1st end part (14a) of the thimble (14). Packing that includes at least 1 tubular elastic membrane (25a, 25b) engages with the smooth part of the spindle (21) and presses against a shoulder on the collar (31) and an assembly (22, 23, 24) for compressing the packing around the spindle (21) to seal the annular space between the spindle (21) and the internal surface of the instrument channel. The spindle (21) and the compression assembly (23, 24) form a sealing device making up an extension tube for the thimble whose external diameter is less than the internal diameter of the instrument channel over at least a part of its length.
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