Nuclear Power Technology Development Section

Intercomparison of techniques for pressure tube inspection and diagnostics

The project is to intercompare inspection and diagnosis techniques for characterization of pressure tubes during their service lifetimes as being used, and developed, by different participating institutions.

Natural Circulation Phenomena, Modelling and Reliability of Passive Systems that Utilize Natural Circulation

The application of passive safety systems is a potential means of achieving simplification and competitive eco-nomics in new nuclear power plant designs. The use of passive systems is not entirely new, and is not unique to any particular line of new reactor designs. But an increased reliance on this approach, making safety func-tions less dependent on active components like pumps and diesel generators, is potentially an important means to achieve reduced costs for future nuclear power plants. Many new reactor designs incorporate passive sys-tems based on natural circulation.

The objectives of this CRP are (1) To establish the state of the art in the area of natural circulation including the consideration of reactor start-up and operation, passive system initiation and operation, flow stability, 3-D ef-fects and scaling laws; (2) to identify and investigate phenomena (e.g. effect of non-condensable gases on heat transfer, thermal stratification, mass stratification, pool heat transfer, moisture carryover, and others) influenc-ing the reliability of passive systems that utilize natural circulation; (3) to identify relevant experimental data-bases for these phenomena, review for completeness, recommend further work as needed, and collect openly available experimental data (4) to examine the ability of current computer codes and models to predict natural circulation and related phenomena that affect the system reliability through sharing assessments, experience, performing standard problem exercises and identifying ways of making improvements, etc. To determine the associated uncertainties, and to perform sensitivity analyses on the importance of various phenomena; and (5) to develop and apply methodologies for determining the reliability of passive systems that utilize natural circu-lation and to introduce this into sample accident sequence analyses.

Optimization of the Coupling of Nuclear Reactors and Desalination Systems

This CRP encompasses research and development programmes in interested Member States pursuing coupling of nuclear systems with seawater desalination process in the field of nuclear reactor design, optimization of thermal coupling, performance improvement of desalination systems and prospects of advanced desalination technologies for the application of nuclear desalination.

Evaluation of high temperature gas cooled reactor performance

This CRP involves the simulation of reactor physics and thermal hydraulic benchmark experiments being con-ducted by the HTTR and HTR-10 experimental reactors in Japan and China, as well as critical experiments on a mock-up of the PBMR core in the ASTRA critical facility in Russia and analytical comparison of reactor phys-ics problems for the GT-MHR with a plutonium core. Participants are providing both pre- and post-test predic-tions of experimental results to contribute to the validation of computer codes for use in the design and safety analysis of modular HTGR reactors.

Updated codes and methods to reduce the calculational uncertainties of LMFR reactivity effects

This CRP will establish the basis for quantifying and eventually decreasing the uncertainties in the calculation of the Doppler, the sodium density and other reactivity coefficients used in LMFR transient analyses.

Advances in high temperature gas cooled reactor fuel technology

This CRP focuses on advances in coated fuel particle technology in areas such as fabrication, quality assurance and control, reactor performance, heating and PIE testing as well as performance modelling.

Studies of Advanced Reactor Technology Options for Effective Incineration of Radioactive Waste

The CRP concentrates on the assessment of the transient behaviour of various transmutation systems. For a sound assessment of the transient and accident behaviour, the neutron kinetics and dynamics have to be quali-fied, especially as the margins for the safety relevant neutronics parameters are becoming small in a “dedi-cated” transmuter. The CRP will integrate benchmarking of transient/accident simulation codes focussing on the phenomena and effects relevant to various critical and sub-critical systems under severe neutron flux chances and rearrangements. The main thrust will be on long time-scale effects of transients initiated by strong perturbations of the core and/or the neutronic source. Changes of flux-shape and power caused by reactivity perturbations in systems with dedicated fuels and various Minor Actinide content will be one focus. For the transient analysis of such transmuters, besides neutronics, thermal-hydraulic and fuel issues are of importance.

The behaviour of different transmuter systems under various transient conditions will be assessed.

The CRP will investigate future needs both for theoretical means (data and codes) and experimental informa-tion related to the various transmutation systems.

The final goal is to deepen the understanding of the dynamics of transmutation systems, e.g., the accelerator driven systems, especially systems with deteriorated safety parameters, qualify the availability methods, specify the range of validity of methods, and formulate requirements for future theoretical developments. Should tran-sient experiments be available, the CRP will pursue experimental benchmark work. Should transient experi-ments be available, the CRP will pursue experimental benchmark work. In any case, based on the results, the CRP will conclude on the potential need of transient experiments and make appropriate proposals for experi-mental programs.

Economic Research on, and Assessment of, Selected Nuclear Desalination Projects and Case Studies

This CRP is to contribute to the IAEA’s, efforts to enhance prospects for the demonstration and eventually for the successful implementation of nuclear desalination in Member States. This is to be achieved through research projects directed towards evaluation of economic aspects and investigation of the competitiveness of nuclear desalination under specific conditions in case studies, identification of innovative techniques leading to further cost reduction and refinement of economic assessment methods and tools.