A Comparison of Different Design Codes on Fatigue Life Assessment Methods

Different pressure vessel and piping design codes and standards have adopted different fatigue analysis methods. In order to make some contribution to current efforts to harmonize international design codes and standards, a review of fatigue analysis methods for a number of selected nuclear and non-nuclear design codes and standards has been carried out. The selected design codes and standards are ASME Boiler and Pressure Vessel Code Section III Subsection NB and Section VIII Division 2, EN 12952, EN 13445, EN 13480, PD 5500, RCC-M, RCC-MRx, JSME, PNAEG and R5. This paper presents the initial review results. The results of the study could be used as part of the on-going work of the Codes and Standards Task Force of the World Nuclear Association (WNA) Cooperation in Reactor Design Evaluation and Licensing (CORDEL) Working Group.

Nuclear Fatigue Analysis Codified Design Rules: Comparison of Cyclic Plasticity Effects

Large uncertainties exist in fatigue life evaluation using existing elastic stress analysis. The usage factor is obtained by comparison of strain amplitude evaluation on different points of the components and the fatigue S-N curve of the material. This paper will review existing codified rules in major nuclear Codes that are proposed as simplified elastic-plastic analysis of strain amplitude. The different formulas proposed by the different Codes are described with their own background document and compared on typical cases. Methods are based on simplified elastic-plastic approach (elastic analysis plus correction factor) with associated material data. The Code comparison includes nuclear Codes, as ASME Boiler and Pressure Vessel Code Section III, French RCC-M and RCC-MRx and German KTA; Russian PNAEG Code and JSME rules are also considered based on specific English version of the Codes for fatigue rules. Two types of components are concerned by the comparison: vessels and piping systems. All these Codes are proposing different Ke and Kv rules based on different assumption. Finally, a first set of recommendation to perform reference inelastic analysis will be presented to improve existing codes on an harmonized way, associated to analytical recommendations, all material properties needed and criteria to apply this modern methods. This review is mainly done in World Nuclear Association (WNA), Cooperation in Reactor Design Evaluation and Licensing (CORDEL) Working Group, Codes & Standards Task Force.

cPKC regulates interphase nuclear size during Xenopus development

Dramatic changes in cell and nuclear size occur during development and differentiation, and aberrant nuclear size is associated with many disease states. However, the mechanisms that regulate nuclear size are largely unknown. A robust system for investigating nuclear size is early Xenopus laevis development, during which reductions in nuclear size occur without changes in DNA content. To identify cellular factors that regulate nuclear size during development, we developed a novel nuclear resizing assay wherein nuclei assembled in Xenopus egg extract become smaller in the presence of cytoplasmic interphase extract isolated from post-gastrula Xenopus embryos. We show that nuclear shrinkage depends on conventional protein kinase C (cPKC). Increased nuclear cPKC localization and activity and decreased nuclear association of lamins mediate nuclear size reductions during development, and manipulating cPKC activity in vivo during interphase alters nuclear size in the embryo. We propose a model of steady-state nuclear size regulation whereby nuclear expansion is balanced by an active cPKC-dependent mechanism that reduces nuclear size.

Method to Select the Countries and Scenarios More Appropriate for the Deployment of SMR

The evolution of nuclear technologies has led to the development of a large number of reactor designs. In particular there is significant and growing interest towards Small Modular Reactors (SMRs), i.e. nuclear reactor of a size between 40MWe and 700 MWe. Several heterogeneous countries are potentially interested in their deployment and approximately twenty advanced SMR designs are under development all over the world. However, both the market dimensions for SMRs and where they may be deployed remain unclear. This paper presents a method for the identification of countries which could be interested in the construction of SMRs and which factors foster their deployment. The presented method, grounded on a comprehensive literature review, is composed of three screenings and comprises the strategic consequences of the Fukushima accident. The first screening selects all the countries of the world that the International Atomic Energy Agency (IAEA) and World Nuclear Association (WNA) indicate as possible market for nuclear reactor in general. The second screening selects countries based on their potential interest in SMR development in the short to medium term. The third screening identifies countries where SMRs are a particularly suitable choice. To perform this last “scenario based” selection the strengths and weakness of the SMRs have been analyzed to define their strategic match with the potential countries. The findings of this investigation reveal the strategic factors promoting the deployment of SMR and provide the basis for a ranking of countries in which these factors could create the market for SMR.

Uranium mining industry views on ICRP statement on radon

In 2009, the International Commission on Radiological Protection issued a statement on radon which stated that the dose conversion factor for radon progeny would likely double, and the calculation of risk from radon should move to a dosimetric approach, rather than the longstanding epidemiological approach. Through the World Nuclear Association, whose members represent over 90% of the world's uranium production, industry has been examining this issue with a goal of offering expertise and knowledge to assist with the practical implementation of these evolutionary changes to evaluating the risk from radon progeny. Industry supports the continuing use of the most current epidemiological data as a basis for risk calculation, but believes that further examination of these results is needed to better understand the level of conservatism in the potential epidemiological-based risk models. With regard to adoption of the dosimetric approach, industry believes that further work is needed before this is a practical option. In particular, this work should include a clear demonstration of the validation of the dosimetric model which includes how smoking is handled, the establishment of a practical measurement protocol, and the collection of relevant data for modern workplaces. Industry is actively working to address the latter two items.