[en] The AC Device represents the key component which makes the SLAR (Spacer Locating and Repositioning) system function. The AC Device produces a continuous electromagnetic force on the spacer in the axial direction when ac power is applied, without any adverse effects on the channel integrity. The AC Device of LIM (Linear Induction Motor) was proven to be safe and easy to operate in the hostile environment of a commissioned CANDU reactor, and is currently being manufactured by Ontario Hydro Research Division for field implementation of the SLAR program

[en] The mathematic models and the stability analysis method are established for analyzing flow-induced-vibration of rod bundles in bounded axial flow. As applications, the vibration characteristics and stability of a 4-rod system are studied. With the flow velocity increment, the system experiences divergence instability and flutter instability. The existence of the axial flow induces the coupling of the movement of the rods. This coupling makes the very complicated vibration modes

[en] Because of their dimensions and the resulting flexibility the storage and transport of fuel element clusters outside the pressure vessel is very problematic. To overcome this difficulty a container has been designed, which permits the transport and appropriate storage of these clusters

No abstract available

[en] Purpose: To optimally position a fuel catcher by mounting a television camera to a fuel catching portion and judging video images by the use of a computer or the like. Constitution: A television camera is mounted to the lower end of a fuel catching mechanism for handling nuclear fuels and a fuel assembly disposed within a reactor core or a fuel storage pool is observed directly from above to judge the position for the fuel assembly by means of video signals. Then, the relative deviation between the actual position of the fuel catcher and that set in a memory device is determined and the positional correction is carried out automatically so as to reduce the determined deviation to zero. This enables to catch the fuel assembly without failure and improves the efficiency for the fuel exchange operation. (Moriyama, K.)

[en] Highlights: • An integrated uncertainty and sensitivity analysis is used for Hewitt-Govan entrainmnet-deposition model. • Areas of high and low uncertainty are presented with quantified uncertainty sources. • Coolant flow is shown as the most influencing parameter for tubular and rod geometry. - Abstract: Uncertainties of numerical predictions play important role in assessment of safety margins in nuclear reactors. In this paper uncertainties of the predictions of the Hewitt-Govan model, which is used to determine the entrainment and deposition rates in phenomenological dryout model, are presented and discussed. Results of the global uncertainty analysis are shown in terms of trends of uncertainty values with respect to the pressure, mass flux and inlet subcooling. Regions of large and small uncertainties are identified and presented in a tabular form. Application of the global sensitivity analysis methods allowed to quantify the sources of uncertainties with high accuracy over large spectrum of experimental conditions. Since the present analysis required calculation of millions of cases, a dedicated fast-running three-field computational code called DARIA has been developed for that purpose. The analysis revealed that the uncertainties of dryout prediction are predominantly resulting from uncertainties of the coolant mass flow rate. The most obvious implication of the presented work is that, when applying the current methodology to predict dryout in rod bundles, the most important parameter, affecting the accuracy of predictions, is the distribution of coolant flow between sub-channels.

[en] Pressure drop measurements have been carried out on three different designs of seven-rod bundles having longitudinally-finned rods. Experiments have also been carried out for different shapes and lengths of spacers. Results obtained are reported in this paper. An analysis of the results indicates that in addition to the pitch-to-diameter ratio, wall-distance to diameter ratio may also have an important influence on the friction factors. For clusters with finned rods an equivalent to diameter as postulated in this article may be a more appropriate parameter for comparison of friction factor for rod clusters with that for smooth tubes on the basis of pitch-to-diameter ratio. The length of the spacer has been found to have a significant influence on the pressure drop across the spacer. (orig.)

No abstract available

[en] This invention concerns an assembly of fuel element spacers for a nuclear reactor, particularly a pressurized water reactor. The purpose of such an assembly is to space out a bundle of nuclear fuel elements in a nuclear reactor assembly, such elements having to be maintained parallel to each other in accordance with a given network. It must also ensure a flexible support for these elements according to successive different areas distributed according to their length, particularly so as to prevent them from vibrating in contact with the movement of flowing liquid coolant environment

[en] The invention concerns a new, simple and inexpensive system for assembling and dismantling a nuclear reactor fuel bundle. Several fuel rods are fitted in parallel rows between two retaining plates which secure the fuel rods in position and which are maintained in an assembled position by means of several stays fixed to the two end plates. The invention particularly refers to an improved apparatus for fixing the stays to the upper plate by using locking fittings secured to rotating sleeves which are applied against this plate