Transition temperature shift

Typical examples of the molality dependence of the swelling curves are shown in Fig. 25 where the swelling curves of NIP A gels immersed in four simple aqueous inorganic salt solutions are demonstrated for various molalities. In each case, with increasing salt molality, the transition temperature shifts to the lower... 

Figure 9 shows the dynamic mechanical spectra of a series of poly-(tetramethylene oxide) /poly (tetramethylene terephthalate) (PTMO/ PTMT) segmented copolymers (67). These materials reveal only one Tg and one Tm analogous to semicrystalline thermoplastics. The magnitude of both transition temperatures shifts progressively higher with increasing... 

Calculation of the so-called fluence factor of the copper impact into the transition temperature shift confirms that for the value fluence about 0.0002 dpa saturation of this factor is observed already. The attempt to separate out the embitterment data into the two components of CEC and AfDg was carried out . It was found that the copper component remains unchanged already due irradiation 0.0005 dpa at 190-200°C of weld surveillance material. Similar analysis for PWR submerged-arc weld material following accelerated irradiation at temperatures in the range 255-315°C shows that copper contribution remains unchanged after irradiation with dose of 0.01 dpa. 

Hiranuma, N., Soneda, N., Dohi, K., Ishino, N., Dohi, N., and Ohata, H. (2004) Mechanistic Modeling of Transition Temperature Shift of Japanese RPV Materials, 30 MPA-Seminar in conjuction with the 9 GermanMapanese Seminar, Stuttgart, October 6 and 7, p. 3.1-3.19. 

In a recent study, a dose-response relationship was found between THC and the transition temperature shift for lecithins [113]. The cholesterol content was again found to influence this effect. 

Similar discordance in a, c, and y at the NI interphase is also observed for 5CB (Figure 7.14d-f), where the analysis has been carried out on the PVT data collected at 0.1 and 80 MPa. Of the extensive PVT measurements on nCB, the only ones reported were those above room temperature. Since 5CB exhibits the NI transition at 308 K under 0.1 MPa, a reliable estimate of the nematic properties is difficult for the ordinary pressure, and the results are shown only for the isotropic state. The NI transition temperature shifts toward higher temperatures with pressure. At 80 MPa, the midpoint... 

The phase transition temperature shift due to substrate influence can be manifested in the measurements of magnetic susceptibility temperature dependence (Fig. 2.45). It is seen that for EuS-PbS multilayer structure both on KCl(lOO) substrate and without it, the magnetic susceptibility maxima are shifted relatively to each other by 2-3 K, the Tc being lower for free standing film. 

The Charpy tests are performed according to the RSE-M, with instrumented ISO tups. The transition curves of the absorbed energy, the lateral expansion and the fracture appearance are determined. The RTndt shift is deduced from the transition temperature shifts at an absorbed energy of 56 J and lateral expansion of 0.9 mm. The measured values are compared to the upper-bound predictions calculated according to the RSE-M Code. 

Transition temperature shifts are shown as a function of fluence in Fig. 4.8 for base metals, welds, HAZ and correlation monitor material. This... 

Transition temperature shifts versus fluence for base metals, weld metals, heat-affected zones and correlation monitor material from French surveillance program. 

The Code specifies that surveillance capsules shall be located within the reactor vessel so that the specimen history duplicates as closely as possible the neutron spectrum, the temperature history and the maximum neutron flux experienced by the reactor vessel. A sufficient number of surveillance capsules shall be provided to monitor the effect of neutron radiation on the reactor vessel materials, that is, the transition temperature shift, ARTndt and the decrease in USE throughout its operating period. A minimum number of capsules is specified depending on the predicted ARTndt value of each testing material at the inside surface of the beltUne of the reactor vessel. In this section, the Japanese surveillance tests program is reviewed. The details of the JEAC 4201 can be found elsewhere (Tomimatsu et al., 2006). Table 4.8 summarizes major revisions of the JEAC 4201. 

The neutron flux level for the PWR surveillance program is approximately 10 n/cm s ( > 1 MeV). The highest fluence of the PWR surveillance data is about 6 x 10 n/cm (E > IMeV) as of 2012. The transition temperature shifts, ARTndtS, of all the PWR surveillance data are plotted in Fig. 4.12 for base metals and Fig. 4.13 for weld metals as a function of neutron fluence. In general, ARTndt increases with fluence, but the values of the shift are not very high. The highest ARTndt values for base metal and weld metal are 88 °C and 131 C, respectively. The transition temperature shift depends mainly on the copper content of steel, and it increases with the copper content. 

In the majority of PWR plants each surveillance capsule has Charpy impact specimens made from the Japanese PWR correlation monitor material. The contents of copper, nickel and phosphorus in this material are 0.09 %, 0.62 % and 0.007 %, respectively. Some of the surveillance data for this material are shown by Tomimatsu et al. (1996). Figure 4.15 shows ARTndt and USE for the correlation monitor material as a function of neutron fluence. As there are a lot of transition temperature shift data as a function of neutron fluence for one specific material, the effect of fluence... 

Transition temperature shifts versus fluence for weld metals from German FWR surveillance results (Langer ef a ., 2000). 

ASTM E 900-02 (2002), Standard Guide for Predicting Radiation-Induced Transition Temperature Shift in Reactor Vessel Materials, E706 (IIF) , American Society for Testing and Materials. 

Eason E, Odette G, Nanstad R and Yamamato T (2007), A Physically Based Correlation of Irradiation-Induced Transition Temperature Shifts for RPV Steel, ORNL/TM-2006/530. Oak Ridge National Laboratory, Oak Ridge, TN. 

Transition temperature shifts for 15Kh2NMFA(A) type steel due to thermal ageing (BM = base metal, WM = weld metal). 

Typical trend curves (mean and 95%) for transition temperature shift in 15Kh2NMFA(A)-type base metal (BM) with 1.1 mass % of nickel. 

Most of the sets were withdrawn and tested by standard procedures before it was concluded that such an approach was unacceptable. Determination of neutron fluences on individual specimens was characterized by a high uncertainty. Differences in neutron fluences within one group of specimens for testing transition temperature shift exhibited high values (i.e. up to 50%). Thus, practically all three sets of two-floor assemblies have... 

Annealing of the RPV materials at 455-470 °C causes changes in the system of copper clusters, namely the growth of their size and the decrease of their density. This low density of copper precipitates has little influence on the mechanical properties of the recovered material. Thus, if annealing leads to a low density of small, nearly pure copper precipitates and low matrix copper content, further neutron irradiation of this neutron-irradiated and annealed material should produce smaller transition temperature shifts than occur under primary irradiation. As follows from the APFIM results, the phosphorus content in the matrix after annealing is recovered approximately to the level of unirradiated material. This means that the influence of phosphorus on the material embrittlement under re-irradiation is substantial. 

The prediction of embrittlement shift in transition temperature is generally based on correlations of measured surveillance CVN transition temperature shifts with specific chemistry variables (generally Cu, Ni, P, Mn and Si) and fluence for the materials of interest. 

The Japanese model in JEAC 4201 (JEAC, 2007) involves an updated two-mechanism model using rate theory and measured microstructure characteristics (Soneda et ai, 2010). The new model provides mean predictions for CVN energy T41, transition temperature shift using a model with coefficients optimized using the most recent complete set of Japanese surveillance data. 

N. Hiranuma, N. Soneda, K. Dohi, S. Ishino, N. Dohi and H. Ohata, Mechanistic modehng of transition temperature shift of Japanese RPV materials , 30th MPA-Seminar in conjunction with the 9th German—Japanese Seminar, Stuttgart, Germany, 6-7 October, 2004. 

In a manner similar to the effects of irradiation on the CVN impact toughness, the fracture toughness is reduced by irradiation and exhibits a transition temperature shift as well as a reduction in/i and tearing modulus. Examples of these effects are shown in Figs 10.9a (Nanstad et al, 1992) and 10.9b Hiser et al, 1984) for two western RPV steels, while the effects on WWER steels are similar. As with CVN impact toughness, the effects of irradiation on the fracture toughness of RPV steels are dependent on the radiation sensitivity of the material which is primarily determined by the specific chemical composition. 

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