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[en] A simple, practical, and reliable analytical method with liquid electrode plasma optical emission spectrometry (LEP-OES) is developed for determination of Na, K, Ca, Sr, and Ba in radioactive waste. Appropriate emission lines for quantification and interferences from co-existing elements have been investigated. Nitric acid concentration in standards and analyte solution is adjusted to 0.80 mol/L because it affects the emission intensities. The spike and recovery tests using actual sample indicate that sample matrix effect is negligible for those measurements. The obtained data by LEP-OES has matched with data from ORIGEN code and inductively coupled plasma optical emission spectrometry within 10% difference. Consequently, the method is successfully applied to real radioactive wastes from reprocessing plant. (author)
[en] The PARAMETER-SF4 experiment was performed at the PARAMETER test facility at FSUE SRI SIA “LUCH” on 21 July 2009 to study the behaviour of a pre-oxidized fuel bundle under conditions of air ingress with a small flowrate and subsequent bottom quenching. Fundamentally the same phenomena are expected during severe accidents at spent fuel pools (SFPs), therefore the data can be used for validation of codes that can be applied for the SFP analysis. The main purpose of the simulation PARAMETER SF4 experiment with the SOCRAT code was to check the consistency of the code models to solve the thermal problem and to simulate the bundle degradation and relocation of the materials as well as the effect of the bundle quenching. (author)
[en] Spent fuel pools (SFPs) are large accident hardened structures that are used to temporarily store irradiated nuclear fuel. Due to the robustness of the structures, severe accidents involving SFPs are generally regarded as highly improbable events. The safety and security of spent fuel pools are continuously re-assessed as new information becomes available or the operating conditions of the plants or pools change. For example, the terrorist attacks in the USA on September 11, 2001, prompted studies on the vulnerability of spent fuel storage facilities to potential terrorist attacks in many countries . More recently, the Fukushima Daiichi nuclear accident  that followed after the Tohoku earthquake on March 11, 2011, has renewed international interest in the safety of spent nuclear fuel stored in SFPs under prolonged loss-of-cooling conditions , although the SFPs and the fuel stored in the pools remained safe during the accident.
[en] Thorium and its compounds have been widely investigated as important nuclear materials. Previous research focused on the potential use of thorium hydrides, such as ThH, ThH, and ThH, as nuclear fuels. Here, we report studies of the anion, ThH, by anion photoelectron spectroscopy and computations. The resulting experimental and theoretical vertical detachment energies (VDE) for ThH are 4.09 eV and 4.11 eV, respectively. These values and the agreement between theory and experiment facilitated the characterization of the structure of the ThH anion and showed its neutral counterpart, ThH to be a superhalogen. ThH, which exhibits a C structure with five Th-H single bonds, possesses the largest known H/M ratio among the actinide elements, M. The adaptive natural density partitioning (AdNDP) method was used to further analyze the chemical bonding of ThH and to confirm the existence of five Th-H single bonds in the ThH molecular anion. (© 2020 Wiley‐VCH GmbH)
[en] Fuel pool cooling is an essential task in the scope of nuclear power applications. During the first years of commercial nuclear power implementation robust fuel pool cooling systems have been developed and used for several decades. Two decades ago the development of a new cooling technology/concept was initiated to ensure prevention of accidents, including fuel damage. The so-called advanced cooling technology offers a modular design system which enables tailor-made robust and cost efficient cooling solutions. However, all the advanced cooling systems feature an indispensable and distinctive fall back option of a passive heat removal in case of a station blackout as most important feature. In contradiction to conventional cooling systems the advanced cooling solutions use immersed heat exchangers to establish an additional safety barrier inside the heat removal chain. This results in the necessity of a free convective heat transfer on pool water side. This in turn requires a special design approach and methodology. Because of the huge nominal heat load and the size of the heat removal systems itself full size test are under economical aspects nearly impossible. In this paper a purpose-built simulation and design methodology is presented, which has been developed and proved in the scope of several first-of-a-kind projects during the last years.
[en] This publication describes decision making in and implementation of asset management for sustainable nuclear power plant operation. It addresses aspects of asset management in nuclear power plants and presents shared experience and lessons identified, based on operational experience and knowledge. Although the publication is aimed at promoting asset management for nuclear power plants, the approach presented can also benefit other nuclear fuel cycle facilities, as they also constitute nuclear assets.
[en] Since the Fukushima Daiichi accident, increased attention has been paid to the vulnerability of the Spent Fuel Pools (SFP). This vulnerability is a concern for SFPs safety because generally the fuel clad is the sole barrier against fission product release in case of dewatering. Also, the potential source term is several times the one present in the reactor vessel. For example, French SFPs can harbour up to 2.5 times the number of fuel assemblies present in the core of a 900 MW(e) reactor. The IAEA “International Experts Meeting on Strengthening Research and Development Effectiveness in the Light of the Accident at the Fukushima Daiichi Nuclear Power Plant”, held in Vienna in 2015, concluded that one priority is to investigate SFP loss of coolant and loss of cooling accidents. The OECD/NEA edited a Status Report on Spent Fuel Pools under Loss-of-Cooling and Loss-of-Coolant Accident Conditions and afterward gathered and expert group to establish a Phenomena Identification and Ranking Table on Spent Fuel Pools under Loss-of-Cooling and Loss-of-Coolant Accident Conditions. Several R&D programs dealing with SFP accidents were carried out. This PIRT concluded to the needs of further R&D concerning SFP accidental conditions and prioritized the topics to be investigated.
[en] This publication summarizes the results of an IAEA technical meeting to review and discuss the analysis, simulation, and modelling of severe accident progression in spent fuel pools. The emphasis was on achieving a better understanding of drivers for improvement to address risks associated with accidents in spent fuel pools, progression to failure of the spent fuel, and the subsequent release of fission products. Discussion sessions enabled the exchange of information regarding the analysis of severe accidents in spent fuel pools, the provision of an overview of current research and development (R&D) activities, and considerations for the planning and execution of further R&D. The meeting served as a forum for Member States to exchange knowledge on current and new code development and methodologies, to identify the gaps for future improvements, and gather information for collaboration on all these aspects.
[en] UK Fast Reactor Activities: - Continued restoration of the Dounreay site: Decommissioning of DFR and PFR. - Activities within the Nuclear Innovation Programme of the Department for Business, Energy & Industrial Strategy (BEIS): Reactor Physics-Coupling of thermal hydraulics, neutronics and fuel performance codes for fast reactors; Strategic Toolkit Knowledge capture from the UK's historical fast reactor programmes. - The BEIS Advanced Modular Reactor (AMR) Feasibility and Development Project: A £ 45 M BEIS-funded project to give potential vendors of advanced (Gen IV) modular reactors the opportunity to qualify for funding to assist in developing their systems. - Continued contributions to European Commission H 2020 projects: ESFR_SMART and SafeG.
[en] This paper/presentation discusses the Canadian Nuclear Safety Commission (CNSC) staff’s regulatory perspective on fuel performance, the impact of PHT chemistry control on fuel reliability and recent CANDU OPEX. Specifically, that fuel performance and reliability need to be assured with a robust chemistry control and fuel inspection regime. This is to ensure, among other things, that chemical damage to the sheaths and deposits on the fuel are precluded. In this context, recent experience with regulating CANDU reactors where coolant chemistry created fuel deposits is presented. (author)