The multi-pass welding on the dissimilar welds can cause the microstructure variation and tensile residual stress gene- ration, which may deteriorate the fatigue lifetime, on the heat affected zone (HAZ). The difference of thermal expansion and conductivity on these welds makes them particularly sensitive to thermal fatigue cracking. But, it is difficult to find the previous researches about a relation between the fatigue lifetimes of the dissimilar welds on real nuclearcomponents and the unique nature (the microstructure variation, residual stress, and different thermal expansion/ conductivity) of these welds. So, in this study, the microstructures, tensile properties and stress distributions of HAZ on nuclearcomponents are predicted by using the semi-analytical method and finite element method. And, the fatigue lifetimes of the dissimilar welds on nuclearcomponents are evaluated by using the stress analysis results and the fatigue analysis procedure of ASME B&PV Code Sec.III. Finally, the effect of the unique nature of the dissimilar welds on fatigue lifetime is reviewed.
The authors have developed and introduced a three-dimensional fully automatic software intended for prediction of crack propagation in complex geometries and material heterogeneities. This development was carried out in an attempt to simulate material selective nature of crack growth in welds of nuclearcomponents involving material heterogeneities including welds. The developed software named FINAS/CRACK, automated the cycle of stress analysis, crack propagation, remeshing of a new domain after the growth, and back to stress analysis to realize such simulations. The effectiveness of the new software was illustrated through several numerical samples and more samples including material heterogeneities will be shown at the time of presentation.
This paper presents the evaluation of a post-tensioned nuclear containment structure for a temporary construction opening in its cylindrical wall. The wall prestressing system consists of post-tensioned helical tendons inclined in a 45 ° pattern. The total number of tendons to be detensioned is determined by performing numerous finite element analyses that reflect the conditions of the containment structure during different construction phases, as well as for plant end-of-life condition. The paper discusses the various models used in the analysis, and provides details on the modeling of prestressing forces induced by the helical tendons. Representative analysis results are also presented.
The USNRC GALL report contains an evaluation of a large number of structures and components. The evaluation results documented in the GALL report indicate that many of the generic existing programs are adequate to manage ageing effects for particular structures or components for license renewal without change. The GALL report also contains recommendations on specific areas for which generic existing programs should be augmented for license renewal and documents the technical basis for each such determination.
ponent. The second phase, known as the 'inelastic phase', is rich in fast components and can nucleate and grow in the transient gel. The long-lived 'interaction network' can tolerate bulk stress against its volume because polymeric molecules can withstand a large degree of deformation, thus allowing individual regions in the polymer to bear mechanical stress. In contrast, free colloidal particles (ine- lastic phase) cannot tolerate the same stress. The phase separation becomes more pronounced when the mole- cules of the slow phase tend to associate  (Figure 1). From our understanding of the dynamic properties of the nucleus, the concept of viscoelastic phase separation could partly explain behaviour of nuclearcomponents. The slow fluid component (DNA) cannot catch up with the deformation rate of phase separation itself and starts to behave like a viscoelastic body. This phase separation process is characterized by the generation of a sponge-like network of the slow component i.e. the chromatin, which is the result of coexistence of 'asymmetry in mobility between the two components of a mixture' and the net- work-forming ability originating from attractive interac- tions between like species . In the case of chromatin the attractive forces are mediated by histone-histone inter- action and ancillary proteins interacting with chromatin . The theory of viscoelastic phase separation predicts that chromatin would adopt a sponge-like structure in the cell nucleus as shown in Figure 2, with fingers of chroma- tin penetrating the nucleoplasm full of rapidly moving protein and RNA molecules. Similar pictures to the one shown in Figure 2 have been obtained using specific DNA staining osmium-ammine B .
Components of the SUMO and DNA repair pathways are re- cruited to parental HSV-1 genomes in the absence of hDaxx, PML, and Sp100. One hallmark of intrinsic resistance to HSV-1 is the recruitment of restrictive factors, including ND10 compo- nents, to nuclear sites associated with parental viral genomes and early replication compartments (18). Because triple depletion of PML, hDaxx, and Sp100 did not completely restore the growth of ICP0-null mutant virus to wt levels, we considered whether re- cruitment of other restrictive host factors remains unimpaired in triply depleted cells. ICP0 induces the widespread degradation of SUMO-conjugated proteins during HSV-1 infection, and the SUMO interaction motifs of PML, hDaxx, and Sp100 are required for their recruitment to the HSV-1-induced foci (17, 63). This implies an important role of the SUMO modification pathway in FIG 4 Triple depletion in HFs improves replication and gene expression of ICP0-null mutant HSV-1. HFs were transduced with a lentivirus expressing shRNA with no cellular target (shneg) or targeting hDaxx, PML, and Sp100 (shDPS). (A) Verification of depletion by immunofluorescence. Cells were simultaneously stained with rabbit anti-hDaxx 07-471 antibody, mouse anti-PML MAb 5E10, and rat anti-Sp100 r26 antibody. Secondary antibodies are described in the legend of Fig. 2. Bar, 10 m. (B) Immunoblot analysis of extracts from the generated cell lines demonstrating depletion of the respective proteins. Antibodies used for detection are described in the legend of Fig. 2. (C) Relative efficiency of plaque formation in depleted and nondepleted HFs. Cells were infected with HSV-1 strain in1863 and ICP0-null HSV-1 strain dl1403/CMV/lacZ at sequential dilutions. At 24 h postinfection, cells were fixed and stained for ␤ -galactosidase expression. Bars represent mean relative efficiencies of plaque formation determined by calculating virus titers in depleted compared to nondepleted (shneg) cells in three independent experiments. A typical example of a stained plaque dilution series is shown at the bottom, with plaques stained in blue. (D) Kinetics of viral protein expression in depleted and nondepleted cells. Cells were infected with wt or ICP0-null HSV-1 at an MOI of 2, and cell lysates were sampled at 0, 4, 6, and 8 h postinfection (h p.i.). The samples were analyzed as described in the legend of Fig. 3.
In current fusion devices, the components located in front of plasma, the so-called plasma facing components (PFCs), sustain severe constraints such as high thermal flux (several MW/m²), erosion, flux of particles. The management of this first material interface is critical from a plasma performance point of view. ITER, as nuclear facility, is initiating a new era for fusion, which will be reinforced for a future fusion power plant which will add specific requirements (sufficient lifetime, a cooling system to produce energy, use of low activation material) while increasing nuclear constraints.
We next asked whether other components of the cytosolic sensing pathway were involved. IFI16 has been reported to signal through STING (Almine, 2017). IFI16 has been reported to signal through STING (Unterholzner, 2010; Almine, 2017) but has also been reported to have STING-independent functions in DNA damage and senescence (Xin, 2003). We therefore decided to test the involvement of STING in the innate immune response to DNA damage to determine if IFI16 was signalling through STING. To study the role of STING in this response, we first used STING-targeting siRNA, to knock down STING levels in HaCaT cells, and this was confirmed at the mRNA and protein level (Figure 16a, b). The STING gel mobility shift observed in HT-DNA treated lanes is indicative of activation-induced STING phosphorylation (Tanaka, 2012). When compared with non-targeting siRNA treated cells, STING knockdown cells had significantly reduced responses to Etoposide treatment as measured by IFN-β mRNA (Figure 16c), and CCL20 mRNA (Figure 16e). The IL-6 mRNA response in STING siRNA treated cells was decreased but not significantly so, this could be an authentic phenotype or due to incomplete knockdown of STING protein (Figure 16d). These results indicated that STING contributes to the Etoposide-induced innate immune response. A slight decrease in H2AX phosphorylation was also observed in STING siRNA treated cells (Figure 16a).
A potentially clear and robust signature would be the detection of the direction of WIMP induced nuclear recoil signals [21, 24]. Such a directional measurement can allow for discrimination of terrestrial, isotropic or solar neutrino backgrounds from WIMP-induced recoils peaked away from Cygnus [22, 25, 26]. The DRIFT , NEWAGE , MIMAC , DMTPC  and D 3  collaborations have developed directional WIMP search time projection chambers. The NEWSdm experiment  has also made progress using nuclear emulsions to measure directions of nuclear recoil tracks. Other methods, for instance columnar recombination in Xenon targets , use of polarised 3 He , carbon nanotube  and anisotropic crystal scintillator  targets are being considered. However, there is concern that multiple scattering of nuclear recoil ionization signals in liquid and solid state target detectors can obscure the directional information of tracks . Also, ranges of nuclear recoils are larger in low-pressure gas TPCs, allowing for better track reconstruction, including both the 3D range component R 3 , and the vector direction (sense) of the recoil.
A possible source of an accidental explosion is the release of explosive liquefied gas from off site storage tanks during transport or land storage. The released gas when combined with air forms a vapor could which can be ignited, resulting in a deflagration or an explosion. Examples of explosive gases include the hydrocarbon gases such as Ethylene, Ethylene oxide, methane, butane, ethane, propane and propylene. The transportation mode may be gas tankers for sea or inland waterway traffic, railway tank cars, tank trucks, or pipe lines. The gases may also be stored in storage areas of the industrial complexes close to the nuclear plant facilities.
The calculation conditions are taken from the USNRC/EPRI PTS benchmark problem A5 as shown in Table 3. Before the PFM analyses, distributions of temperature and thermal stress are calculated by FE analyses according to the given temperature and pressure transients. The following parameters are chosen for sensitivity analyses: annealing timing, recovering ratio, chemical components, evaluation method of embrittlement, crack detection ratio of NDI, aspect ratio of semi-elliptical surface crack, WPS and evaluation method of fracture toughness. Annealing conditions and recovery of D RT NDT and D USE are summarized in Table 4. These conditions are decided by using the embrittlement evaluation method
To investigate several unresolved issues and to improve upon the existing equations for integrity assessment of piping components, a comprehensive Component Integrity Test Program (CITP) was initiated at BARC, India. As a part of this program, several fracture tests have been conducted on straight pipes and pipe bends, which forms a valuable data base. Simultaneously, analytical work have been undertaken to propose the improvements in the existing equations for optimized and more accurate integrity assessment of piping components. As an outcome of this analytical investigations, generalized equation of η pl and γ have been proposed to evaluate J-R curve, study of
Elbow as a pipe bend element is a non-structural component but the most common and critical element in Nuclear Power Plant (NPP) because of its flexibility. Generally, small amount of relative displacement is considered to occur between the piping elements even under ultimate loading condition such as earthquake loading and so the large relative displacement effect of the piping is not well studied. However, in case of base-isolated NPP, such a large relative displacement can be occurred at crossover piping between seismic isolation structures and non-seismic isolation structures during earthquakes and the piping must maintain structural soundness against the displacement and continue its critical function (NUREG, 2014).
The DIALIFE diagnostic system has been developed by the Institute of Applied Mechanics Brno,Ltd (IAM) in co-operation with Dukovany Nuclear Power Plant (NPP). The developing of DIALIFE programming system is natural continuation of the long term service which IAM have provided for Dukovany NPP. DIALIFE system runs in Dukovany NPP, Mochovce NPP and Temelin NPP and is continuously updated.
It is worth noting that the scope of BS EN 1998-4 1.1 (4) states that “this standard may not be complete for those facilities associated with large risks of population or the environment”. Furthermore 1.1 (4) states that “although large diameter pipelines are within the scope of this standard, the corresponding design criteria do not apply for apparently similar facilities, like tunnels and large underground cavities”, which can appear to conflict with the scope of ETC-C for nuclear safety-related tunnels and galleries. ASCE 4-98 generally requires some form of SSI analysis but for certain special structures, such as buried pipes, conduits and earth-retaining walls, it allows the use of more simplified methods. For example, the well-known Wood method and Mononobe-Okabe method can be used to determine dynamic soil pressures of earth-retaining walls given certain conditions. Taking into account the scope of BS EN 1998- 4, for seismic analysis of nuclear safety-related tunnels and gallery structures it is recommended to undertake a validation of the approach given by Annex B of BS EN 1999-4, if adopted, using an appropriate approach according to ASCE 4-98.
The irradiation induced deformation and creep usually happens to graphite components irradiated by fast neutron influence in nuclear reactors, especially in the high temperature-gas-cooled reactors. Therefore, it is necessary and important to analyze and assess the mechanical behavior of graphite components under irradiation conditions during their design process. The irradiation induced deformation can be dealt with in the same way always used to deal with the thermal expansion but the irradiation induced creep should be analyzed by means of the viscoelastic model which is commonly analyzed by two methods, one of which is called the state equation method or the incremental method, and the other is the hereditary method. A FEM method using the hereditary method to analyze behavior of the irradiated graphite components is described in detail in this paper. It has the advantages of the hereditary method, and in the creep computation, the component volume is considered incompressible. The stress and deformation calculation of the graphite block of side reflector of HTR-10, high temperature reactor- test module in the Institute of Nuclear and New Energy Technology of Tsinghua University, Beijing, has been conducted, considering irradiation induced deformation and creep.
In DiD level 3, avoidance of core damage caused by seismic motion should be required, and seismic core damage probability will be introduced as the index of RP. This index, i.e. core damage probability, is consisted of three safety functions such as reactivity control, core cooling and containment cooling. These functions have some of SSCH, for example, reactor building and reactor vessel as structure, ECCS as system, components such as pumps and valves, and human. Structure including these items can be expressed as Figure 3.