[en] The measurement of gamma rays produced by the inelastic scattering of neutrons in the ⁹³Nb(n,n'γ)⁹³Nb reaction is reported. The work provides information on the excited energy levels of the ⁹³Nb nucleus and its associated gamma-ray decay transitions. Differential gamma-ray production cross sections were obtained at incident neutron energies of 0.50 MeV through 1.90 MeV and 3.50 MeV through 5.00 MeV. Angular distribution determinations were made at 1.10 and 1.60 MeV. A revised nuclear energy scheme containing 24 levels through 2.173 MeV is presented. The scheme is constructed from the gamma spectra and experimental excitation functions. Thirty-four of the observed gamma rays can be assigned to transitions between these levels. Comparison of experimental data with calculated theoretical predictions based on the statistical theory and compound-nucleus theory also lead to spin and parity assignments for a number of the energy levels. The gamma rays were measured by a 34cc GeLi spectrometer system used in conjunction with a Van de Graaff 3.2 MeV accelerator as a pulsed neutron source. The spectrometer consisted of a 34cc coaxial GeLi detector centered in a NaI(Tl) annulus and surrounded by a massive shield. Time-of-flight techniques and anticoincidence gating were used to improve the gamma-ray spectra. The spectrometer is described in detail and gamma-ray spectra and production cross section data are given for the ²⁷Al(n,n'γ), Fe(n,n'γ) and ²⁰⁹Bi(n,n'γ) reactions as an illustration of the spectrometer system capabilities

[en] Strontium activity has been removed from Magnox pond waters by the in-situ precipitation of titanium hydroxide, and subsequent ultrafiltration to remove the strontium-loaded precipitate from the effluent. The titanium hydroxide produced in this way was sub-micron in particle size and had a high adsorption capacity. Strontium decontamination factors in excess of 100 have been achieved after the addition of only 2g/m³ of titanium to the effluent followed by ultrafiltration. Continuous operation of 0.1m² plastic, hollow fibre ultrafiltration modules has been demonstrated. After the addition of 4g/m³ of titanium, effluent was concentrated ten-fold by ultrafiltration and then further concentrated by sedimentation, the supernate being recycled to the ultrafiltration process. The overall process volume reduction factor from effluent to titanium hydroxide sludge was 500 with an overall strontium decontamination factor in excess of 100. Least membrane fouling was observed when using hollow fibres of the largest available diameter and when operating in turbulent flow. It was estimated that a membrane flux of 2m/d could, under appropriate conditions, be maintained for periods of almost 20 days. A flowsheet for the operation of a large ultrafiltration plant is discussed. (author)

[en] A collimating apparatus for a radiation source from which X or Gamma radiation is emitted through an aperture means, the dimensions of said aperture means defining a boundary of the desired beam to be projected, said collimating apparatus defining means for projecting towards a remote target a beam of radiation which is substantially non-diverging from said defined boundary in at least one direction, said collimating apparatus comprising an elongated sandwich assembly of a plurality of layers of material means exhibiting relatively high radiation attenuation characteristics, said attenuating layers being spaced apart and separated from one another by interleaved layers of material means exhibiting relatively low radiation attenuation characteristics, said sandwich assembly being adapted for lengthwise disposition adjacent the aperture means in the path of and throughout the defined boundary of the radiation emitted through the aperture means, such that said attenuating layers are parallel to the desired direction of the projected beam with said interleaved spacing layers providing multiple direct paths for the radiation comprising the projected beam

[en] A collimator is disclosed for minimizing radiation exposure and improving resolution in radiation imaging devices. The collimator provides a penetrating beam of radiation from a source thereof, which beam is substantially non-diverging in at least one direction. In the preferred embodiment, the collimator comprises an elongated sandwich assembly of a plurality of layers of material exhibiting relatively high radiation attenuation characteristics, which attenuating layers are spaced apart and separated from one another by interleaved layers of material exhibiting relatively low radiation attenuation characteristics. The sandwich assembly is adapted for lengthwise disposition and orientation between a radiation source and a target or receiver such that the attenuating layers are parallel to the desired direction of the beam with the interleaved spacing layers providing direct paths for the radiation

[en] In order to improve the resolution in computer-aided planigraphy in radiation diagnostics one needs a non-diverging scanning beam which is as thin as possible. A suitable collimator has a longitudinal layer structure with numerous strongly damping layers of tantalum or lead which are spaced by intermediate layers with relatively less radiation damping. The layer structure is placed along the beam and is placed between slit aperture and target surface, wherby the penetrable layers release the beam. The layers may be parallel, concentric or spirally connected according to the desired beam limitation. Besides an improved picture auality, the radiation exposure outside the layer to be investigated is considerably reduced due to the back of scattered radiation. (ORU)

[en] This paper discusses a number of the interesting experiences encountered at the Douglas Point Nuclear Power Station. Sufficient background with respect to the basic process, equipment location, and commissioning history is given so that those not familiar with the station may follow the remainder of the paper. Three commissioning philosophies followed in the commissioning of Canadian nuclear power stations are mentioned: (1) no ordinary water used for commissioning heavy-water systems: (2) fuelling machines used for initial fuel loading; (3) no portable steam-generating equipment for preliminary turbine-generator run up. Against this background the following experiences are mentioned: low power physics measurements; fuel channel replacement and faulty booster removal; heat transport pressure control; ion-exchange resin in the heat transport system; heat transport pumps; boiler level control; possible fretting of pressure tubes; turbine operation; heavy-water experience. The paper concludes by mentioning some important lessons learned from the experience to date and states confidence in the future of Douglas Point Generating Station, and future Canadian nuclear power stations. (author)

[en] For several years Ontario Hydro has been striving to improve safety, and other aspects of its operation, through the involvement of workers, supervisors, and managers in making decisions. At the time of the recent reorganization of Ontario Hydro a 'Business Improvement Process' was estabIished, based on several quality improvement processes used before the reorganization. This process is jointly sponsored by management and the two main employees' unions. One part of the process supports the formation of multidisciplinary teams to solve defined probIems. This paper describes the success of one such team ('The Dose Busters') in reducing radiation dose to fuel handling workers at the Bruce B Nuclear Generating station. The team had been formed several years ago, with members from mechanical maintenance, control maintenance, operations, and engineering support, Ied by a mechanicaI maintainer. lt had made some improvements that reduced dose but its members feIt limited by the lack of a structured probIem-solving process. The team was revitalized through training in structured problem solving provided as part of the Business lmprovement Process. This process leads the team to a cIear definition of the main problem to be solved. After getting support from their leadership team to solve the problem, the team develops a good solution, impIements their solution, and checks its effectiveness, making further corrections if needed. AnaIysis of dose data showed that the greatest opportunity for improvement was by reducing work time for repetitive jobs on the reactor face. The team devised and impIemented improvements expected to save a totaI dose of 36 Rem (0.36 Sv) over the station life. An important secondary benefit has come from the team's careful analysis of their own work practices. They discovered and corrected other industrial safety problems that normal practices had not detected. This has helped keep the enthusiasm on the team high as the members could see they are directIy contributing to making their workplace safer. (author)

[en] New ultrafiltration processes developed for the treatment of low and medium active radioactive wastes, were applied successfully to a variety of simulated and real wastes, including magnesium alloy clad spent storage fuel pond waters, reprocessing plant solvent wash liquors, plutonium production effluents and mixed site effluents. After initial laboratory scale feasibility experiments the process was scaled up successfully, using a variety of different ultrafiltration modules. The information accumulated on membrane performance, membrane fouling and flux restoration techniques, and ancillary equipment performance was used to design a much larger demonstration pilot plant. This plant has been constructed and is now processing continuously each day over 1m³ of a real radioactive effluent. (author)

[en] Ultrafiltration-based processes have been developed for the treatment of low and medium-active radioactive wastes. Actinides such as U, Pu and Am were found to be present as insoluble species in many effluents and were separated with high efficiency, by direct ultrafiltration. Soluble nuclides, including complexed actinides, Sr and Cs, were removed at > 99 % efficiency by combined processes, in which very low concentrations (< 10 g/m³) of ultrafine activity absorbing precipitates were added. The new ultrafiltration processes were applied successfully to a variety of simulated and real wastes, including magnesium alloy clad spent storage fuel pond waters, reprocessing plant solvent wash liquors, plutonium production effluents and mixed site effluents. After initial laboratory scale feasibility experiments, the process was scaled up, using a variety of different ultrafiltration modules. An inorganic, tubular ultrafiltration module was selected for more detailed investigation and an automated mini-unit was constructed for longterm evaluation. The information thus accumulated on membrane performance, membrane fouling and flux restoration techniques, and ancillary equipment performance was used to design a much larger demonstration pilot plant. This plant is now processing continuously each day over 1 m³ of a real radioactive effluent

[en] Poster presentation. 1 fig