Abstract: A locking piston drive system and valve assembly is provided for shutdown of a nuclear reactor. "Chatter" in a check valve assembly which occurs during charging and/or re-charging of control fluid within a control line is eliminated by providing a valve head and a resisting portion defined on the valve head to resist movement of the valve head when it is urged from sealing engagement on its seat during the charging or re-charging procedure.

Abstract: An inflatable packer and a method for its use are provided for introduction into a subterranean well bore on a conduit. A pinch can form in the inflatable elastomeric bladder of the packer during inflation, forming a seal on the central body, which obstructs the effective passage of pressured fluid, thereby obstructing effective inflation and deflation of the bladder. The packer provides a tension means such that, after an initial amount of inflation, a predetermined amount of inflation pressure must be introduced to the bladder before an end of the bladder is released for axial movement relative to the central body, allowing a gap to form between the bladder and the body and a predisposition to radially expand before full inflation, to diminish the bladder's propensity to pinch and seal on the body.