１．はじめに沸騰水型原子炉（BWR（Boiling Water Reactor））における主蒸気には、冷却材である水の放射線分解によって生じる水素と酸素がわずかに存在し、水蒸気の凝縮により非凝縮性気体である水素と酸素（混合ガス）が取り残され、機器の頂部で徐々にその濃度が上昇することが開発当初から知られていた。そこで、混合ガスが蓄積する可能性のある原子炉圧力容器、熱交換器等の頂部にはベント系を設置するとともに、復水器に集められた混合ガスについては、水素と酸素を結合させ水に戻すための再結合器を設置する設計......

The pipe rupture accidents due to combustion of radiolysis gas in BWR piping occurred in 2001. TENPES and JANTI got “The design guideline to prevent pipe rupture accident due to combustion of radiolysis gas in BWR piping” ready and proposed about ideal method of the piping placement design to BWR. This report is the summary of the method to evaluate the possibility of accu mulation of radiolysis gas in BWR piping which is mentioned in the guideline....
英字タイトル:
The development of the guideline to prevent combustion of radiolysis gas inBWR piping

From the engineering development to actual application of the new maintenance technique used for the maintenance activities of a nuclear reactor in operation, the JANTI Guide line, “the Guideline on the Application Process of a Maintenance Technique“ was developed to clarify activities to be checked or examined in each process. In engineering deve lopment, all activities are provided to be checked or examined at each process followed further, such as standardization process. It is important to carry out sh...
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Guideline on Application Process of Techniques Developed for Maintenance Activities

背景および概要近年、国内の沸騰水型原子力発電プラント（BWR）炉心シュラウドや再循環系（PLR）配管等の低炭素ステンレス鋼製機器の溶接部で、多数の応力腐食割れ（Stress Corrosion Cracking: 以下、SCC） が確認された［1］。2003年10月には健全性評価制度が法制化され、SCC 等の欠陥が発生した機器についても、機械学会維持規格［2］に基づく技術的評価により健全性が確認されれば継続運転が可能となった。ただし、PLR配管のSCCに ついては、従来の超音波探傷検査（UT）では十分な精......

One year has passed since Electronic Journal of Advanced Maintenance (EJAM) was started on the website of Japan Society of M aintenology (ISM) May 25“, 2009. “New Technology' (NT) is one of the EJAM categories, and introduces widely advanced techniqu es developed or modified for maintenance. Twenty-two NT articles have been introduced on EJAM website so far as of May 25t“, 2010. This report describes the concept of NT, general features of NT articles, actual performance and future wishes for NT....
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Current Status of EJAM ‘New Technology

JANTI Guideline on underwater laser beam clad welding for preventive maintenance against SCC was published. This paper introduces the summary of that guideline. Underwater laser beam welding has good advantages for the repair and mitigation work for operating nuclear plants' reactor internals. Since it does not need to drain the water from RPV, preparation before the work can be very concise, and dose rate that workers suffer can be controlled in very low level. And heat input during the welding procedure ...
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Guideline on Underwater Laser Beam Clad Welding for preventive maintenance

Inspection and Evaluation Guidelines for reactor internals has been taken into the Rules on Fitness-for-Service for Nuclear Power Plants of The Japa n Society of Mechanical Engineers. Now, It is a base of the maintenance plan of each Nuclear Power Plant. In the maintenance in the future, Inspecti on for the structures after repair, the replacement and the preventive maintenance becomes important. This paper introduces the systematization and the idea of the repair, the replacement and the preventive maint...
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The systematization and the idea of the repair, the replacement and the preventive maintenance in the Inspection and Evaluation Guidelines for Light Water Reactor Internals.

Stress corrosion cracking of welding portion has found in many domestic and foreign BWR reactor internals and Primary Loop Recirculation piping. Also, repair and preventive maintenance technologies for SCC has been developed and/or adopted to BWRs in recent years. This paper introduces the sample of these technologies, such as seal-welding fo r SCC on BWR reactor internals, preventive maintenance technology for PLR piping such as Corrosion Resistant Cladding, Internal Polishing and Induction Heating Stress...
英字タイトル:
Repair and Preventive maintenance Technology for BWR Reactor Internals and Piping