Alloy 600, highly heat resistant and corrosion resistant, is widely used in nuclear power plant components, such as re actor pressure vessel nozzles and steam generator nozzles. However, some Alloy 600 components have recently experience d defects in Japan and abroad. In this regards, enhanced maintenance measures are required to deal with this problem. This paper describes representative defects; PWSCC in Alloy 600 components and summarizes countermeasures in advance....
英字タイトル:
Maintenance Techniques on PWSCC of Ni Alloys Used as PWR Pressure Boundary Materials

It is necessary to confirm whether the feed water nozzle inside corner has crack by eddy current testing, to enable long-term operation of a plant. Therefore, we performed eddy current testing using various types of specimen to collect basic data (probability and length measurement accuracy) of the eddy current testing methods, complying with JEAG4217. As a result, eddy current testing was effective for the inspection of feed water nozzle inside corner. ...
英字タイトル:
Eddy current testing technique for feed water nozzle inside corner of nuclear reactor pressure vessel

規格基準動向1．はじめにAlloy600はPWR環境でSCC（以下PWSCC）の感受性があることから保全対策と関連規格の整備はPWR（加圧水型原子炉）の課題の一つとして認識されている。近年、Alloy600が使用されているPWR上蓋に海外で損傷事例が見られていたため、万一の場合の補修工法の確立は優先度の高い課題として検討されてきた。上蓋の補修にはき裂の存在する開先面に遠隔操作により３次元制御で健全な溶接を行う高度な技術を要する。さらに、規格についても、複雑形状のバウンダリ部におけるき裂進展評価、延性破壊評......

Abstract: This study evaluates the applicability of eddy current testing to the detection and sizing of fatigue cracks embedded in Inconel weld overlay. Welded plate specimens, which model head penetration welds and their weld overlay, are fabricated, and fatigue cracks are artificially introduced into the specimens. Eddy current inspections are performed using a uniform eddy current probe driven with 10 kH z, and all of the fatigue cracks are detected with clear signals. Subsequent numerical inversions ...
英字タイトル:
Detection of embedded fatigue cracks in weld overlay and evaluation of minimum thickness of the weld by means of eddy current testing

Abstract: The secondary system pipe rupture occurred on August 9,2004, at Mihama nuclear power plant unit 3. Eleven workers, who were preparing for an annual outage that was to start from August 14th, suffered burn injuries, of who five died. We sincerely and deeply apologized to the victims and their families. We will make every possible effort to ensure that such an accident will never happen again. It is estimated that the disturbed flow of water, downstream of the orifice, caused erosion / corrosion an...
英字タイトル:
Lesson learned from secondary pipe rupture at Mihama Unit 3 and our future strategy