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Seki, Masayuki; Kihara, Yoshiyuki; Kaito, Takeji; Tsukada, Tatsuya*; Motoki, Kazuhiko*; Hirako, Kazuhito*
Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12
Oxide Dispersion Strengthened (ODS) steel has been developed as an advanced fuel cladding tube for sodium cooled fast reactors in Japan Atomic Energy Agency (JAEA) to attain the target burn up of 150 GWd/t in the bundle average because of its excellent swelling resistance and high mechanical strength in high temperature. If conventional TIG welding is applied to the ODS welding, it is difficult to obtain necessary mechanical strength at the weld zone because of the formation of porosity. It is formed by the argon bubbles which initially dissolve in the matrix and grow up under the high temperature during welding. Therefore JAEA has been conducted the development of pressurized resistance welding (PRW) technology for ODS cladding tube, which is one of the solid state welding methods. This paper describes in the development of PRW technology, an ultrasonic test method for detecting weld defects, the result of machine strength measurement examination in weld part and the result of fuel pin irradiation examination using nuclear reactor.
Kihara, Yoshiyuki; Seki, Masayuki; Fujio, Ishibashi,; Hirako, Kazuhiko*; Tsukada, Tatsuya*
JNC TN8430 2005-002, 27 Pages, 2005/07
JNC-TN8430-2005-002.pdf:32.93MB
The irradiation test to gather the creep rupture data of the MARICO-2 test pieces manufactured from Oxide Dispersion Strengthened steel (ODS steel) cladding tube in JFY 2004. Therefore, to improve the reliability of the strength evaluation of the ODS steel cladding tube, it was planned to supplement the creep rupture data in that had been obtained so far. The strength evaluation test pieces supplied to this examination was manufactured by the request of the JNC OEC system nuclear fuel engineering group. This test pieces were manufactured by using Martensitic ODS and Ferritic ODS as well as MARICO-2 and CMIR-6. The specification of the test piece was same as two steel types. The problem did not occur for manufacturing the test pieces (20 pices of Martensitic ODS and 12 pices of Ferritic ODS) from April 5, 2005 to May 13, 2005. It was provided for JNC OEC System Division nuclear fuel group at the May, 2005.
Seki, Masayuki; Ishibashi, Fujio; Kihara, Yoshiyuki; Hirako, Kazuhito*; Tsukada, Tatsuya*
JNC TN8410 2005-009, 131 Pages, 2005/04
JNC-TN8410-2005-009.pdf:41.38MB
The development of the welding technology for the ODS steel was started in JFY1987. The first welding examination used the tungsten inert-gas (TIG) welding method and the YAG pulse laser welding method. However, the existing fusion welding methods significantly degrade strength at the welded section, because large size of blowholes appears at the weld and induce coagulation of oxides to generate coarser particles. To solve this problem, we have developed pressurized resistance welding (PRW) as a solid phase welding method.The appropriate conditions, e.g. electric current, voltage and contact force, were selected. For the PRW welded specimens, the tensile, internal burst and creep rupture tests were conducted and its integrity was confirmed. In addition, an ultrasonic inspection method has been developed to assure non-destructively integrity of the welding between cladding and end-plug.
Seki, Masayuki; Ishibashi, Fujio; Kihara, Yoshiyuki; Hirako, Kazuhiko*; Tsukada, Tatsuya*
JNC TN8430 2004-003, 78 Pages, 2005/03
JNC-TN8430-2004-003.pdf:61.9MB
Irradiation test in BOR-60 at RIAR to judge practical use prospect of ODS cladding tube at early stage is planned as Japan-Russia a joint research. Irradiation test is done for five years from June, 2003 aiming at burn-up 15at%.The first stage irradiation test was achieved target burn-up 5at% in May, 2004.The second stage irradiation test begins in May, 2005. JNC Tokai welded martensitic ODS cladding tube and upper endplug by pressurizing resistance welding, and inspected, it was transported to RIAR. As well as last time, Use of long scale cladding tube caused problem that bending transformation occurred in cladding tube by welding pressure. However, we solved this problem by adopted a changeable pressurizing system. This system can suppress the transformation of the cladding tube because it can set the pressurizing power when beginning to connect it low. Manufacturing was enabled by using this system. A permissible value of the welding condition was expanded by having adopted the changeable pressurizing system, it has a advantage for the design of the hot device. The cladding tubes with upper endplug passed the inspection by OEC on 15 December 2004 were shipped on 13 January 2005 for RIAR.
Seki, Masayuki; Ishibashi, Fujio; Kihara, Yoshiyuki; Tsukada, Tatsuya*; Hirako, Kazuhiko*
JNC TN8430 2004-002, 49 Pages, 2005/03
JNC-TN8430-2004-002.pdf:72.34MB
The irradiation test by MARICO-2 and CMIR-6 is planned aiming to the irradiation characteristic of ODS cladding tube. The test pieces of MARICO-2 and CMIR-6 were manufactured by using Martensitic ODS cladding tube and Ferritic ODS cladding tube. The specification of the test pieces was same as two steel type. The test pieces of Martensitic ODS were manufactured from February 19, 2004 to March 11, 2004.(MARICO-2:38test pieces (in clueded 11pieces reserve and QA sample) and CMIR-6:6 test pieces). The test pieces of Ferritic ODS was manufactured from August 17, 2004 and September 22, 2004.(MARICO-2:32test pieces(in clueded 11pieces reserve and QA sample) and CMIR-6:6 test pieces). The problem did not occur for manufacturing the test pieces. Martensitic ODS test pieces was provided for JNC OEC System Division Nuclear fuel group at the May 2004 and Ferritic ODS test pieces was provided for JNC OEC System Division Nuclear fuel group at the October 2004.
Kono, Shusaku; Seki, Masayuki; Fujio, Ishibashi,; Hirako, Kazuhiko*; Tsukada, Tatsuya*
JNC TN8430 2003-010, 28 Pages, 2003/07
JNC-TN8430-2003-010.pdf:2.18MB
The defect occurred at the resistance welding zone is very minute and therefore cannot be identified by X-ray inspection. Then, the ultrasonic examination method, in which the resolution of the defect is higher than that of the X-ray inspection method, has been developed. The ultrasonic wave sounds straight easier in the material than X rays, excels in defecting the micro defect. However, the pulse amplitude of ultrasonic wave is influenced by the shape and direction of the defect. Then, the ultrasonic inspection equipement, in which the ultrasonic probe and the sample rotation axis are controlled to drive with the pulse motor and the defect data (position and size)are analized by image processing ultrasonic signal, was developed to measure the shape and the position of defect accurately. However, an ultrasonic examination method is the comparative inspection method. Therefore, the standard test block or the reference block is indispensable to guarantee the defectability and the ultrasonic echo sensibility of the inspection device. The standard test block is provided in JIS etc, it is needed to defect the peculiar defect occurred at the resistance welding zone. Then, the method of processing a standard test block is examined, the standard test block was made experimentally by electric discharge processing and diffusion junction method. The ultrasonic echo sensitivity and the threshold for image processing were proofread by using the standard test block, the ultrasonic inspection and metallographic inspection were executed. Comparing the ultrasonic inspection results with the metallographic inspection results, the detectability of defect depth and the measurement accuracy were proved to be 3
m and with errors less than 10m respectively. From these results, the effectireness of proofreading the ultrasonic inspection condition by the standard test block was confirmed. Moreover, it was confirmed that there was a peculiar relationship between the depth ...
Kono, Shusaku; Seki, Masayuki; Ishibashi, Fujio; Hirako, Kazuhiko*; Tsukada, Tatsuya*
JNC TN8410 2003-009, 108 Pages, 2003/05
JNC-TN8410-2003-009.pdf:9.54MB
The welding condition and the heat-treatment condition were optimized to evaluate welding properties of the martensitic ODS steel cladding tube. The test pieces for evaluation of strength properties of the welded zone were produced by the optimized welding condition. In order to evaluate the strength of the welded zone, the internal creep rapture test, the single axis creep rapture test, the burst test and the tensile test were conducted. Following results were obtained in these tests. (1) Weld ability. An excellent welding characteristic was observed. The micro cracks, etc. were not served at the joint starting point. The joint starting poonts were connected uniformly with errors less than 0.05mm. It is considered that an excellent welding characteristic was result of homogeneous micro structure of cladding material. (2) End plug material. In case of the material of end plug was martensitic ODS steel as same as that of cladding tube, the micro structure and the precipitation state carbide near the welded zone were found to be almost same as that of cladding tube. (3) Optimization of heat-treatment condition. The heat treatments of normalizing (10501
C) and tempering (780C) were performed after welding and the micro structure near the welded zone was the isometric structure with low dislocation density, the precipitation state of carbide was uniform as same as that of cladding tube. These heat treatments can relax the residual stress accumulated when welding; it is considered that these heat treatments after welding are indispensable. (4) Strength of welded zone. The strength of the welded zone was found to be equal to that of cladding tube in all the strength tests. Therefore, it is concluded that the welding technology for the martensitic ODS steel is completed.
; Seki, Masayuki; ; *; *
JNC TN8430 2003-003, 249 Pages, 2003/04
JNC-TN8430-2003-003.pdf:247.75MB
Irradiation test in BOR-60 at RIAR to judge practical use prospect of ODS cladding tube at early stage is planned as Japan-Russia a joint research. RIAR does fuel design of fuel pin used for this joint research. JNC manufactures ODS cladding tube and bar materials (two steel kind of martensite and ferrite), upper endplug production. They are welded by pressurized resistance welding, and are inspected in JNC Tokai, transported to RIAR. And RIAR manufactures vibration packing fuel pin. On the upper endplug welding by pressurized resistance welding method, we worked on the problems such as decision of welding condition by changing the size and crystallization of cladding tube and the design of endplug, and the chucking device remodeling to correspond to the long scale cladding tube welding system (included handling) and of quality assurance method. Especially, use of long scale cladding tube caused problem that bending transformation occurred in cladding tube by welding pressure. However, we solved this problem by shortening the distance of cladding tube colette chuck and pressure receiving, and by putting the sleeve in an internal spece of welding machine, losing the bending of cladding tube. Moreover, welding defects were occurred by the difference of an inside state, an inside defect, and recrystallization of cladding tube. We solved the problem by inside grinding for the edge of tube, angle beam method by ultrasonic wave, and ultrasonic wave form confirmation. Manufacturing process with long scale claddng tube including heat-treatment to remove combustion return and remaining stress was established besides, Afterwards, welding of ODS cladding tube and upper endplug. As the quality assurance system, we constructed [Documented procedure (referred to JOYO)] based on [Document of the QA plan] by OEC. Welding and inspection were executed by the document procedure. It is thought that the quality assurance method become references for the irradiation test in JOYO ...
; Seki, Masayuki; ; *; *
JNC TN8410 2002-013, 88 Pages, 2003/01
JNC-TN8410-2002-013.pdf:39.21MB
In the internal creep rapture test, the breakage was caused at the resistance welded area of ODS steel cladding tube. In order to investigate the cause of the breakage, the microstructure of the replica specimens extracted from the welded area was observed by transmission electron microscopy (TEM), and the residual stress near the welded area was measured by X-ray diffraction method (XRD). Following results were obtained in this test. (1)Presumption of the cause of the breakage in the internal creep rapture test for ferritic ODS steel. The breakage was supposed to cause by the stress concentration of the micro crack in the folded area of welding boundary resistance welding, and the grain sliding along the elongated grain boundary. These can be improved by optimizing welding conditions as plunging length of cladding, angle melting face etc. (2)Presumption of the cause of the breakage in the internal creep rapture test for martensitic ODS steel. The breakage was supposed to cause by the declination of high temperature strength of ferritic steel for end plug, the micro crack caused at the folded area of melding and the strength declination of the melded boundary. These can be improved by use of ODS steel for end plug, stress release or re-annealing and re-tempering at about 780C after melding in order to reduce coarsening of aggregation of carbide. (3)Measurement results of residual stress. The residual stress both of ferritic and martensitic ODS steel at the resistance-welded area was 500MPa at a maximum. In heat treating applied after melding, the residual stress was 64MPa and for ferritic ODS steel it was 150MPa at the surface, and 170MPa at the cross section of the resistance-welded area, and at a maximum. Therefore heat treatment conditions need to be adjusted as lengthening more heat treatment time etc.
Endo, Hideo; Seki, Masayuki; ; *; *
JNC TN8410 2001-004, 45 Pages, 2001/02
JNC-TN8410-2001-004.pdf:6.53MB
(1)Purpose. Mechanical strength in the position welded by resistance welding system was examined in 1999. The test specimens were destroyed in the welding position in a shorter time than expected in the creep tsst. Therefore, test specimens were prepared to evaluate the cause of destruction. (2)Procedure. Inner-pressure enclosed creep test specimens were prepared by resistance welding method. Cladding material with low deviation of thickness and high re-crystallization rate was used. Heat treatment after resistance welding was performed to remove the influence of residual stress and the precipitation of carbides. (3)Summary of result. (a)Before preparation of specimens, the welding condition was fixed. Three test specimens were prepared. Two specimens without heat treatment were transported to MMS in Oarai Engineering Center on Aug, 4, 2000. One specimen with heat treatment was transported to MMS after evaluating the residual stress to get optimum heat treatment condition. (b)Specimens were prepared with welding end plugs to both ends of ferritic ODS cladding. Enclosing sides were welded with highly strong Ferritic/Martensitic steel end plugs. The other sides were welded with ferritic ODS end plugs. (3)Some kinds of electrical wave data were obtained during performing welding. position was evaluated with supersonic detector after performing welding. (4)Mechanical strength of welding position in high temperature 800C was confirmed to be equal to or larger than that of cladding material. (4)Conclusion. The highly qualified specimens in the present were successfully prepared.
Endo, Hideo; Seki, Masayuki; ; *; *
JNC TN8410 2000-007, 89 Pages, 2000/03
JNC-TN8410-2000-007.pdf:6.28MB
(1)Outline of examination. Various test specimens were made to evaluate and confirm the weld strength properties of the oxide dispersion strengthened (ODS) cladding tube material (martensitic and ferritic steel), which had been manufactured in JFY 1997. The examination consisted of tensile tests (RT,650C, 700C, 800C), internal pressure creep tests, internal pressure burst tests, and a rapid heating burst tests. (2)Examination results. The results of the tensile tests are as follows: (ferritic and martensitic) (a)All test specimens from RT to 700C failed in the tube. The weld zones had not failed. (b)The test specimens at 800C failed in the weld zones. There was little elongation. (ferritic) (a)The weld zone had fine grain structure and carbide precipitates. (martensitic) (a)Carbide had precipitated in the weld zone. From these results, the strength of weld zone decreased extremely at temperatures exceeding the endurance limit (700C) All of the internal pressure burst test specimens and the rapid heating burst test specimens failed in the tube and not the weld zone. (3)The quality assurance method of the test specimens. The weld reliability of the test specimens were confirmed by the process control of the welding conditions, by using control test specimens, and ultrasonic testing. Confirmation of the process control of the welding conditions; current wave, the voltage waveform, the accelerogram, and the displacement ripple in the welding process was recorded to assure an abnormal value had not occurred. (Process control of welding condition) The results the current waveform, voltage waveform, accelerogram, and the displacement waveform were excellent. (test specimens) The weld joint was excellent based on metallography examination. (Ultrasonic testing) The length of the weld joint was measured and found to be adequate. The reliability the weld joint can be assured by using the above-mentioned method.
Endo, Hideo; Seki, Masayuki; ; *; *; *
JNC TN8430 2000-002, 30 Pages, 1999/12
JNC-TN8430-2000-002.pdf:1.62MB
None
Nishiyama, Motokuni; Kamimura, Katsuichiro; Seki, Masayuki; Tsukada, Tatsuya*; Ishibashi, Fujio; Isaka, Kazuhiko*
PNC TN8410 95-046, 81 Pages, 1995/01
None
Seki, Masayuki; Kihara, Yoshiyuki; Hirako, Kazuhito*; Motoki, Kazuhiko*; Tsukada, Tatsuya*
no journal, ,
no abstracts in English
Seki, Masayuki; Kihara, Yoshiyuki; Tsukada, Tatsuya*; Motoki, Kazuhiko*; Hirako, Kazuhito*
no journal, ,
no abstracts in English
Tanno, Takashi; Yano, Yasuhide; Tsukada, Tatsuya*; Sakamoto, Kan*; Yamashita, Shinichiro
no journal, ,
no abstracts in English
Tanno, Takashi; Yano, Yasuhide; Tsukada, Tatsuya*; Sakamoto, Kan*; Yamashita, Shinichiro
no journal, ,
FeCrAl-ODS stainless steel cladding with Al has been developed to improve oxidation resistance for accident tolerant fuel of LWRs. The strength of weld part may decrease due to growth of fine oxide particles, when the weld method with fusion is used for the end cap joining of FeCrAl-ODS stainless steel. For FeCrAl-ODS stainless steel cladding for fast reactors, the pressurization resistance welding (PRW) mood which is solid-state welding has been developed by an atomic organization. It is reported the results of joining tests that applied the PRW method about a FeCrAl-ODS stainless steel.