[en] The effect of fuel bundle geometry using the subchannel code ASSERT has been evaluated to enhance the thermalhydraulic performance. Based on the configuration of a standard 37-element fuel bundle, the element diameter in center ring has been changed while those of other rings are kept as the original size. (author)

[en] The International Conference on Future of Heavy Water Reactors (HWR-FUTURE) was held in Ottawa, Ontario, Canada on October 2-5, 2011. The conference comprised of various case studies, presentations and roundtable discussions on several pertinent topics dealing with the fast emerging Heavy Water Reactor or HWR technology. This conference addressed the challenges faced by the sector and assisted in planning feasible methods to combat them. Emphasizing effectively on developments and issues, knowledge exchange and technology transfer, and establishing prospective collaborations on reactor design, fuel design, material and chemistry, thermal hydraulics and safety, and operating experience for HWRs, presented were paper presentations, plenary sessions, live demos and practical solutions pertaining to these issues.

[en] This paper presents the MARS-KS assessment results on B9802 SBLOCA test performed in RD-14M test facility. Through the simulation results, it is provided that MARS-KS well predicts the thermal hydraulic behavior in the system. However, the calculated FES temperature trend at middle region of channel, and steam condensation in steam generators show inconsistency in comparison with test data. This study suggest that a further study on the heat transfer model prediction considering bundle effect in the large diameter long horizontal pipe, and condensation model along the u tube is required to have more accurate code prediction. (author)

[en] Atomic Energy of Canada Limited's (AECL) Passive Autocatalytic Recombiner (PAR) is a passive device used for hydrogen mitigation under post-accident conditions in nuclear reactor containment. The PAR employs a proprietary AECL catalyst which promotes the exothermal reaction between hydrogen and oxygen to form water vapour. The heat of reaction combined with the PAR geometry establishes a convective flow through the recombiner, where ambient hydrogen-rich gas enters the PAR inlet and hot, humid, hydrogen-depleted gas exits the outlet. AECL's PAR has been extensively qualified for CANDU and light water reactors (LWRs), and has been supplied to France, Finland, Ukraine, South Korea and is currently being deployed in Canadian nuclear power plants. (author)

[en] Until the recent past, moderator chemistry has remained interesting but unexciting. Over the past two to three years moderator chemistry has become more interesting and far too exciting! This paper will discuss issues that have occurred and potential changes to design requirements of components, in order to keep moderator chemistry interesting rather than exciting. (author)

[en] The International Atomic Energy Agency (IAEA) works with its Member States and multiple partners worldwide to promote safe, secure and peaceful nuclear technologies. To catalyse innovation in nuclear power technology in Member States, the IAEA coordinates cooperative research, promotes information exchange, and analyses technical data and results, with a focus on reducing capital costs and construction periods while further improving performance, safety and proliferation resistance. This paper summarizes the recent IAEA programme to support technology development for heavy water reactors. (author)

[en] The R-134a test loop is a forced-flow experimental facility for the study of heat transfer properties of R-134a under subcritical and supercritical thermodynamic conditions. The loop is designed to operate with pressures as high as 6 MPa and temperatures up to 140 °C. The intended mass flux is in the range of 500-6000 kg/m²s for the experiments with subcritical thermodynamic states and 500-4000 kg/m²s for supercritical conditions. The loop has been designed to accommodate a variety of test-section geometries, ranging from a straight circular tube to a 7-rod bundle, achieving heat fluxes up to 2.5 MW/m² depending on the test section geometry. The design of the loop allows for easy reconfiguration of the test-section orientation relative to the gravitational direction and adjustment to the length of the test section. (author)

[en] The IAEA's system for tracking fuel movement in an on-load refuelled heavy-water reactor is robust, but an opportunity remains to exploit the wealth of data streaming from the reactor vault during operation and provide real-time, third-party monitoring of reactor status and history. This concept of Operational Transparency would require that large amounts of operational data be reduced in near-real time to a small subset of high-level information. Operational Transparency would enhance the IAEA's ability to monitor the state of the core to an unprecedented level. This paper provides an overview of the novel concept of Operational Transparency in heavy water reactors, using potential application to CANDU reactors as an example, and explores some of the technical challenges that will need to be solved for efficient implementation. (author)

[en] A comprehensive technology demonstration program is seen as an important component of the overall safety case, especially for a novel technology. The objective of such a program is defined as providing objective and auditable evidence that the technology will meet or exceed the relevant requirements. Various aspects of such a program are identified and then discussed in some details in this presentation. We will show how the need for such a program is anchored in fundamental safety principles. Attributes of the program, means of achieving its objective, roles of participants, as well as key steps are all elaborated. It will be argued that to prove a novel technology, the designer will have to combine several activities such as the use of operational experience, prototyping of the technology elements, conduct of experiments and tests under representative conditions, as well as modeling and analysis. Importance of availability of experimental facilities and qualified scientific and technical staff is emphasized. A solid technology demonstration program will facilitate and speed up regulatory evaluations of licensing applications. (author)

[en] Complex flow fields are encountered in many reactor components and processes. Measurement and analysis of various flow parameters are very important for optimal design, experimental determination of safety margins and verification of CFD and thermal hydraulics codes. Development of image capture hardware and digital image processing technique in Particle Image Velocimetry (PIV) has made possible to map complex flow fields instantaneously at thousands of points with very high temporal and spatial resolution. PIV is a non intrusive and very flexible technique. In this technique using synchronized operation of laser and CCD camera, seeded flow is illuminated by pulsing laser sheet and images of seeded particles are recorded on CCD camera. The displacement of the particles is measured in the plane of the image and used to determine the velocity of the flow. Image plane is divided into small interrogation regions. Velocity vectors are calculated with the help of cross correlated images obtained from two time exposures. This paper describes 2D PIV System used, flow mapping and verification of CFD codes for pipe flow, submerged jet, thermal stratification in water pool and Fluidic Flow Control Device (FFCD) proposed to be used in advanced accumulator of Emergency Core Cooling System (ECCS). (author)