[en] There is disclosed in the present application, a decontamination system for reactor vessels. The system is operatable without entry by personnel into the contaminated vessel before the decontamination operation is carried out and comprises an assembly which is introduced into the vertical cylindrical vessel of the typical boiling water reactor through the open top. The assembly includes a circular track which is centered by guideways permanently installed in the reactor vessel and the track guides opposed pairs of nozzles through which water under very high pressure is directed at the wall for progressively cutting and sweeping a tenacious radioactive coating as the nozzles are driven around the track in close proximity to the vessel wall. The whole assembly is hoisted to a level above the top of the vessel by a crane, outboard slides on the assembly brought into engagement with the permanent guideways and the assembly progressively lowered in the vessel as the decontamination operation progresses. The assembly also includes a low pressure nozzle which forms a spray umbrella above the high pressure nozzles to contain radioactive particles dislodged during the decontamination

No abstract available

No abstract available

No abstract available

[en] The quenching of diffraction oscillations in the Ar-N₂ system is investigated computationally. (AIP)

No abstract available

No abstract available

No abstract available

[en] Vib-rotational transitions in proton-H₂ collisions are treated by making the sudden approximation for the rotational degree of freedom and retaining a full quantum mechanical close-coupling description of the vibrational excitations. The centrifugal sudden parameter is taken as l' (final orbital angular momentum) in the sudden amplitude since only degeneracy-averaged cross sections are of interest. The strong rotational coupling in this system requires a Legendre polynomial expansion of the orientation dependent sudden T-matrix which greatly simplifies the differential as well as the integral cross section expressions. Numerical results are reported at 4.67 and 10 eV, an energy range in which vibrational excitation increases four-fold and pure rotational excitation in n=0 decreases by a factor of two. At the lower energy, good agreement is found in the comparison with experimental probabilities for the pure rotational excitation apart from a spurious rainbow maximum in the j=1→7 transition which apparently is the result of intermediate vibrational excitations. This effect, which is likely an artifact of the H₃⁺ surface, persists at 10 eV and is also present in the vib-rotational transitions. Rotational excitation is found to be relatively stronger the higher the vibrational excitation and this feature is confirmed by the beam experiments at 10 eV. (Auth.)

[en] Using the diabatic ground state H⁺₃ surface given in analytic form by Giese and Gentry, a coupled-states study of the rotational excitation of H₂ (taken as a rigid rotor) by proton impact is made at 3.7 eV. Transitions 0→j', with j'=0,2,4,...,26, are considered, and one finds a broad distribution in final rotor state j' which is consistent with recent beam experiments. Despite long-range rotational coupling produced by the charge-quadrupole interaction, the coupled-states method gives a good description of the rotational excitation process as is demonstrated by comparison to standard close-coupling cross sections. Intermultiplet transitions (neglected in the coupled-states approximations) are shown to be less important in the high energy limit