Download or read book Reanalysis of Swelling and Irradiation Creep Data on 316 Type Stainless Steels Irradiated in the FFTF and Ph nix Fast Reactors written by MB. Toloczko and published by . This book was released on 2000 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: In comparing results of irradiation creep experiments conducted by researchers in France and those by researchers at Pacific Northwest National Laboratory in the United States, quite different values for the creep-swelling coupling coefficient were reported. The differing coefficients complicated the understanding of the growing data base on irradiation creep. However, upon careful consideration, the French and US results showed key differences in experimental technique and analysis. The French and US irradiation creep experiments were conducted with several important differences that were initially thought to be of little consequence. One difference was related to whether stress-free swelling or stress-enhanced swelling was measured and used in calculating the creep strains. Inspection of irradiation creep results published by the French also showed their technique for extracting the creep-swelling coupling coefficient was different than that used by the present authors. In an effort to better understand the origin of the differing creep coefficients, data from the French and US experiments was reanalyzed taking into account these differences. In performing this reanalysis, completely consistent results were obtained.

Download or read book Determination of Creep Compliance and Creep swelling Coupling Coefficients for Neutron irradiated Titanium modified Stainless Steel at 00 C written by and published by . This book was released on 1991 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation creep data from FFTF-MOTA at ∼400°C were analyzed for nine 20% cold-worked titanium-modified type 316 stainless steels, each of which exhibits a different duration for the transient regime of swelling. One of these steels was the fusion prime candidate alloy designated PCA. The others were various developmental breeder reactor heats. The analysis was based on the assumption that the B0 + DS creep model applies to these steels at this temperature. This assumption was found to be valid. A creep-swelling coupling coefficient of D ≈ 0.6 × 10−2 MPa−1 was found for all steels that had developed a significant level of swelling. This result is in excellent agreement with the results of earlier studies conducted in EBR-II using annealed AISI 304L and also 10% and 20% cold-worked AISI 316 stainless steels. There appears to be some enhancement of swelling by stress, contradicting an important assumption in the analysis and leading to an apparent but misleading nonlinearity of creep with respect to stress.

Download or read book Comparison of Irradiation Creep and Swelling of an Austenitic Alloy Irradiated in FFTF and PFR written by FA. Garner and published by . This book was released on 1999 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comparative irradiation of identically constructed creep tubes in the Fast Flux Test Facility (FFTF) and the Prototypic Fast Reactor (PFR) shows that differences in irradiation conditions arising from both reactor operation and the design of the irradiation vehicle can have a significant impact on the void swelling and irradiation creep of austenitic stainless steels. In spite of these differences, the derived creep coefficients fall within the range of previously observed values for 316 SS.

Download or read book The Relationship Between Swelling and Irradiation Creep in 20 Cold Worked 316 Stainless Steel written by MB. Toloczko and published by . This book was released on 2000 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The relationship between swelling and irradiation creep was investigated using eight sets of pressurized tubes, representing two heats of 20% cold-worked 316 stainless steel irradiated at either 550°C, 575°C, 600°C, and 670°C in the FFTF-MOTA to doses of 79-84 dpa. After reaching these exposures, the tubes were clearly being affected by the "creep cessation" phenomenon. Many of the tubes had already reached the previously observed maximum strain rate of 0.33%/dpa characteristic of creep cessation. Fortuitous failure of fourteen tubes allowed the separation of creep and swelling strains in the creep cessation regime, showing that the maximum strain rate limitation was reached long before the maximum swelling rate of 1%/dpa was reached. Thus, the creep contribution was declining as the swelling rate increased throughout the irradiation.

Download or read book Determination of Creep Compliance and Creep swelling Coupling Coefficients for Neutron irradiated Titanium modified Stainless Steel at 400 Degree C written by and published by . This book was released on 1991 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation creep data from FFTF-MOTA at (approximately)400°C were analyzed for nine 20% cold-worked titanium-modified type 316 stainless steels, each of which exhibits a different duration for the transient regime of swelling. One of these steels was the fusion prime candidate alloy designated PCA. The others were various developmental breeder reactor heats. The analysis was based on the assumption that the B0 + DS creep model applies to these steels at this temperature. This assumption was found to be valid. A creep-swelling coupling coefficient of D (almost equal to) 0.6 x 10−2 MPa−1 was found for all steels that had developed a significant level of swelling. This result is in excellent agreement with the results of earlier studies conducted in EBR-II using annealed AISI 304L and also 10% and 20% cold-worked AISI 316 stainless steels. There appears to be some enhancement of swelling by stress, contradicting an important assumption in the analysis and leading to an apparent but misleading nonlinearity of creep with respect to stress.

Download or read book Irradiation induced Creep in 316 and 304L Stainless Steels Fast Neutrons written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent results are presented from the in-reactor creep experiments that are being conducted by Argonne National Laboratory. The experiments consist of four subassemblies that contain helium-pressurized as well as unstressed capsules of 316 and 304L stainless steels in several metallurgical conditions. Experiments are being irradiated in row 7 of the EBR-II sodium-cooled fast breeder reactor. Three of the subassemblies are being irradiated at temperatures near 400°C, and the fourth subassembly is being irradiated at a temperature of 550°C. Creep and swelling strains were determined by profilometer measurements on the full length of the capsules after each irradiation cycle. The accumulated neutron dose on the 304L capsules at 385°C was 45 dpa; on the 316 capsules at 400°C, 40 dpa; and on the 316 capsules at 550°C, 25 dpa. It was found that the in-reactor creep rates were linearly dependent on hoop stress, with the exception being capsules of 316 stainless steel that had been given long-term carbide aging treatment and then irradiated at 550°C. Those capsules exhibited much higher creep and swelling rates than their unaged counterparts. For the metallurgical conditions where significant swelling was observed (solution-annealed 304L and aged 316 stainless steels), it was found that the in-reactor creep rates were readily fit to a model that related the creep rates to accumulated swelling. Additionally, it was found that the stress-normalized creep rate for 20%-cold-worked 316 stainless steel at a temperature of 550°C was 1.6 times that observed at 400°C.

Download or read book Irradiation Creep Deformation of Modified 316 and 15Cr 20Ni Base Austenitic Fuel Elements Irradiated in FFTF written by S. Ukai and published by . This book was released on 2001 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation creep of modified 316 (PNC316) and 15Cr-20Ni base austenitic stainless steels was determined using the diametral change of the fuel pins, which were irradiated under the fission gas pressurized condition in FFTF to a peak displacement damage of 107 dpa in PNC316 and 120 dpa in 15Cr-20Ni base. The creep compliance B0 and creep-swelling coupling coefficient D were found to be 1.1 to 3.0 x 10-6 MPa-1 dpa-1 and up to 1.3 x 10-2 MPa-1 for instantaneous volumetric swelling rate, respectively. Those are almost the same level as those derived using the pressurized tubes irradiated in FFTF-MOTA. D values tend to decrease and disappear with developing void swelling.

Download or read book Irradiation Creep and Swelling of Various Austenitic Alloys Irradiated in PFR and FFTF written by and published by . This book was released on 1996 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to use data from surrogate neutron spectra for fusion applications, it is necessary to analyze the impact of environmental differences on property development. This is of particular importance in the study of irradiation creep and its interactions with void swelling, especially with respect to the difficulty of separation of creep strains from various non-creep strains. As part of an on-going creep data rescue and analysis effort, the current study focuses on comparative irradiations conducted on identical gas-pressurized tubes produced and constructed in the United States from austenitic steels (20% CW 316 and 20% CW D9), but irradiated in either the Prototype Fast Reactor (PFR) in the United Kingdom or the Fast Flux Test Facility in the United States. In PFR, Demountable Subassemblies (DMSA) serving as heat pipes were used without active temperature control. In FFTF the specimens were irradiated with active ("°5C) temperature control. Whereas the FFTF irradiations involved a series of successive side-by-side irradiation, measurement and reinsertion of the same series of tubes, the PFR experiment utilized simultaneous irradiation at two axial positions in the heat pipe to achieve different fluences at different flux levels. The smaller size of the DMSA also necessitated a separation of the tubes at a given flux level into two groups (low-stress and high-stress) at slightly different axial positions, where the flux between the two groups varied d"0%. Of particular interest in this study was the potential impact of the two types of separation on the derivation of creep coefficients.

Download or read book Irradiation Creep in Type 316 Stainless Steel and US PCA with Fusion Reactor He written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation creep was investigated in type 316 stainless steel (316 SS) and US Fusion Program PCA using a tailored spectrum of the Oak Ridge Research Reactor in order to achieve a He/dpa value characteristic of a fusion reactor first wall. Pressurized tubes with stresses of 20 to 470 MPa were irradiated at temperatures of 330, 400, 500, and 600°C. It was found that irradiation creep was independent of temperature in this range and varied linearly with stress at low stresses, but the stress exponent increased to 1.3 and 1.8 for 316 SS and PCA, respectively, at higher stresses. Specimens of PCA irradiated in the ORR and having helium levels up to 200 appM experienced a 3 to 10 times higher creep rate than similar specimens irradiated in the FFTF and having helium levels below 20 appM. The higher creep rates are attributed to either a lower flux or the presence of helium. A mechanism involving interstitial helium-enhanced climb is proposed. 17 refs.

Download or read book Stress and Temperature Dependence of Irradiation Creep of Selected FCC and BCC Steels at Low Swelling written by MB. Toloczko and published by . This book was released on 2004 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: A large amount of data on irradiation creep of face centered cubic (FCC) and body centered cubic (BCC) steels have been analyzed and published by the present authors, but a recent reanalysis of these data have provided further insight into irradiation creep behavior. The present paper looks at the stress and temperature dependence of creep at low swelling for selected 316 stainless steels and HT9 steels irradiated at temperatures from 400-670°C. Analysis of the creep data has revealed that a transition from a lower creep rate with a stress exponent of one to a higher creep rate with an unknown stress exponent occurs in FCC and BCC steels at moderate stresses, and the transition stress is approximately the same for both classes of steels. Due to limited data at higher stresses, the nature of the creep behavior at stresses greater than the transition stress cannot be unambiguously defined. One possibility is that the stress exponent is transitioning from a value of one to a value greater than one. Another possibility is that the creep compliance value is transitioning to a higher value while the stress exponent remains at a value of one. The creep compliance coefficients of the FCC and BCC steels have also been carefully reanalyzed in the regime where the stresses are lower than the transition stress, and in this regime there is a clear delineation in the creep compliance values between 316 stainless steels, titanium-modified 316 steels, and HT9 steels as a function of temperature.

Download or read book Uniaxial and Biaxial Creep rupture of Type 316 Stainless Steel After Fast Reactor Irradiation written by A. J. LOVELL and published by . This book was released on 1970 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Temperature Dependence of Swelling in Type 316 Stainless Steel Irradiated in HFIR High Flux Isotope Reactor written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The temperature dependence of swelling was investigated in solution-annealed (SA) and 20% cold-worked (CW) type 316 stainless steel irradiated to 30 dpa at 300 to 600°C in the High Flux Isotope Reactor (HFIR). At irradiation temperatures less than or equal to 400°C, a high concentration (2 to 4 x 1023 m−3) of small bubbles (1.5 to 4.5 nm diam) formed uniformly in the matrix. Swelling was low (

Download or read book Swelling Microstructural Development and Helium Effects in Type 316 Stainless Steel Irradiated in HFIR and EBR II written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work examines the swelling and microstructural development of a single heat of 20%-cold-worked type 316 stainless steel irradiated to produce displacement damage and a high, continuous helium generation rate, in the High Flux Isotope Reactor (HFIR). Similar irradiation of the same heat of steel in the Experimental Breeder Reactor (EBR)-II is used as a base line for comparing displacement damage accompanying a very low continuous helium generation rate. At temperatures above and below the void swelling regime (approx. 350 to 625°C) swelling is greater in HFIR than in EBR-II. In the temprature range of 350 to 625°C, cavity formation, precipitation and dislocation recovery are both enhanced and accelerated in HFIR, often causing swelling at lower dose than in EBR-II. In HFIR, however, cavities appear to be bubbles rather than voids. They are about 10 times smaller and 20 to 50 times more numerous than voids in EBR-II. Thus, the swelling becomes greater in EBR-II than in HFIR for 20%-CW 316 in the void swelling temperature ranges as fluence increases. Such differences in swelling and microstructural behavior must be understood in order to anticipate the behavior of materials during fusion irradiation.

Download or read book Uniaxial and Biaxial Creep rupture of Type 316 Stainless Steel After Fast Reactor Irradiation written by and published by . This book was released on 1970 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Irradiation Creep in Austenitic Stainless Steels at 60 to 400 C with a Fusion Reactor Helium to Dpa Ratio written by M. P. Tanaka and published by . This book was released on 1990 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation creep was investigated in the alloys--prime candidate alloy (PCA), Japanese Fusion Energy Program (JPCA), and American Iron and Steel Institute (AISI) 316 (UNS S31600) stainless steel. Tubes pressurized to stress levels of 50 to 400 MPa were irradiated in the Oak Ridge Research Reactor (ORR) with the neutron spectrum tailored to achieve the fusion reactor helium:dpa value of 12 appm/dpa in AISI 316 stainless steel. Irradiation temperatures of 60, 330, and 400°C were investigated, and the irradiation produced 8 dpa and a maximum of about 100 appm helium. Irradiation creep rates of 2.2 to 14x10-4MPa-1dpa-1 were observed at 60°C. At 330 and 400°C irradiation creep rates of 1.3 to 3.5x10-4 were observed, similar to those found previously in similar experiments in the ORR. The low temperature irradiation creep was interpreted in terms of a new model for irradiation creep based on transient climb-enabled glide. The results are important in the design of experimental fusion reactors where temperatures below 100°C are being considered for the operation of high flux components.

Download or read book In Reactor Deformation and Fracture of Austenitic Stainless Steels written by EE. Bloom and published by . This book was released on 1979 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental technique for determining in-reactor fracture strain was developed and demonstrated. Differential swelling between a specimen holder and a test specimen with a lower swelling rate produced uniaxial deformation in 304 and cold-worked 316 stainless steel specimens. In-reactor deformations of 0.7 to 2.1 percent were achieved in Type 304 stainless steel previously irradiated to fluences up to 8.8 x 1026 neutrons (n)/m2 without fracture. These strains are significantly higher than found in postirradiation creep-rupture tests on similar specimens. From the measured strain values and published irradiation creep data and correlations, the stress levels during the irradiation were calculated. On the basis of previous postirradiation creep-rupture results, many of the specimens that did not fail would be predicted to fail. Thus we conclude that the in-reactor rupture life is longer than predicted by postirradiation tests.

Download or read book Reduction of Irradiation Induced Creep and Swelling in AISI 316 by Compositional Modifications written by JF. Bates and published by . This book was released on 1981 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies involving high fluence irradiations of compositionally modified AISI 316 stainless steel have demonstrated that the irradiation-induced creep and swelling of this alloy can be modified through a selective choice of alloying elements. Irradiation-induced swelling of specimens irradiated to fluences of 7 to 12 x 1022 neutrons/cm2 (E > 0.1 MeV) is strongly influenced by the concentration of alpha-stabilizing elements such as silicon and molybdenum. Relative minima and maxima in swelling versus composition diagrams are shown to exist. Irradiation-induced creep strain of AISI 316 is, in general, reduced by the same elements which reduce irradiation-induced swelling. It was found that the compositional dependence of both swelling and creep in this alloy system can be described through a description of the screening of dislocation strain fields. Compositional modifications which increase the mobility of the screening agents or allow the formation of more effective screening agents will decrease the swelling and irradiation creep. This screening results in a decrease in the interstitial-dislocation bias, which results in lower swelling and in-reactor creep.