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Journal Articles

Development of PRW welding technology for 9Cr-ODS cladding tube

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.

JAEA Reports

Manufacturing of ODS Test Pieces for Evaluation of Strength -Result of Test Pieces Manufacturing-

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.

JAEA Reports

Plug-Welding of ODS Cladding Tube for BOR-60 Irradiation Test-2; Determination of Welding Condition and Actual Results of Welding

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.

JAEA Reports

Manufacturing of ODS Test Pieces for MARICO-2 and CMIR-6; Results of Test Pieces Manufacturing

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.

Journal Articles

Pressurized Resistance Welding Technology Development in 9Cr-ODS Martensitic Steels

Seki, Masayuki; Kono, Shusaku; Kihara, Yoshiyuki; Kaito, Takeji; Ukai, Shigeharu; Hirako, Kazuhiko*

Journal of Nuclear Materials, 329-333, p.1534 - 1538, 2004/00

 Times Cited Count:32 Percentile:88.15(Materials Science, Multidisciplinary)

Welding technology for fuel cladding and end-plugs made of ODS steel has been developed to apply for the fast reactor fuel pin fabrication at Tokai-works of JNC. A pressurized resistance welding (PRW) method is utilized as solid phase welding. The method is based on electrical resistance heating of the components while maintaining a continuous force sufficient to forge weld without melting of the components. The contact force between cladding and end-plug is given by pneumatic-hydraulic system. The welding parameters, e.g. electric current, voltage and contact force, are controlled by a programmable system. The appropriate conditions are selected to be a 700 Kgf contact load with 16 kA current for 20 ms after holding for pre-heating by 6 kA current. For relieving the residual stress, the post-welded heat-treatment is performed in the condition of tempering at 1053 K for 10 min. A metallugically bonded welds has been formed by the PRW method, keeping the original dispersed distributio

JAEA Reports

Development of Quality Assurance System for Resistance Welding by Ultrasonic Examination -Fabrication of STB for Resistance Welding and Ultrasonic Examination-

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$$mu$$m and with errors less than 10$$mu$$m 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 ...

JAEA Reports

Development of Resistance Welding Process(VI)

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$$^{circ}$$C) and tempering (780$$^{circ}$$C) 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.

Journal Articles

Welding Technology Development in 9Cr-ODS Martensitic Steels

; ; Ukai, Shigeharu; Kaito, Takeji; Hirako, Kazuhiko*

Proceedings of 11th International Conference on Fusion Reactor Materials (ICFRM-11), 87 Pages, 2003/00

None

Oral presentation

Development of PRW technology for ODS steel, 12; Strength evaluation test by using artificially-defected test pieces

Seki, Masayuki; Kihara, Yoshiyuki; Hirako, Kazuhito*; Motoki, Kazuhiko*; Tsukada, Tatsuya*

no journal, , 

no abstracts in English

Oral presentation

Development of PRW technology for ODS steel, 13-2; Strength evaluation test with artificially-defected test pieces

Seki, Masayuki; Kihara, Yoshiyuki; Tsukada, Tatsuya*; Motoki, Kazuhiko*; Hirako, Kazuhito*

no journal, , 

no abstracts in English

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