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

Electronic Journal of Advanced Maintenance (EJAM) has been issued on the website of Japan Society of Maintenology (JSM) on May 25th, 2009. ‘New Technology’ (NT) is one of the EJAM categories, and introduces widely advanced techniques developed or modified for maintenance to developing countries of nuclear energy. EJAM NT has achieved to publish two or three articles in average by every three months for these seven years. In this paper, as well as classification and organization of relevant techniques in ...
英字タイトル:
Achievement of EJAM ‘New Technology’ and Its Status

The JSME Committee on Power Generation Facility Codes is developing a fatigue evaluation method by flaw tolerance. The ASME B& PV Code Section XI has Non-mandatory Appendix L, which provides a flaw tolerance method for fatigue evaluation when a cumulati ve usage factor (CUF) of a component is greater than 1.0. In order to develop a flaw tolerance method for the JSME Codes, post ulated initial flaws, capability of nondestructive examination, compatibility to rules and flaw tolerance codes are discussed....
英字タイトル:
Development of Fatigue Evaluation Using Flaw Tolerance Method

１．まえがき東海第二発電所（1978年11月営業運転開始）は、第21回定期事業者検査中の2005年（平成17年）5月、図１に示すシュラウドサポートシリンダ軸方向溶接継手（以下「V8」という）3箇所に応力腐食割れ（SCC）と推定される割れが確認され、（社）日本機械学会（以下JSME）の維持規格、及び（社）日本原子力技術協会（以下原技協）の炉内構造物点検評価ガイドライン（以下ガイドライン）を適用した評価により一定期間内の構造健全性を示し、割れを補修することなく継続使用し、3年、7年、10年経過後の最初の定......

Similar cracking events have been occurring on steam generator nozzles of Japanese PWR plants since the first case was found at Mihama-2 in September 2007. These cracks were found by eddy current test (ECT) prior to performing a kind of shot peening as a preventive measure on dissimilar metal weld (DMW), a nd were considered as primary water stress corrosion cracking (PWSCC) based on cause investigation. It was pointed out that surface finishing such as grinding or machining played an important role on cra...
英字タイトル:
Cracking Events on PWR Steam Generator Nozzles and Its Relationship to Inspection Rules

This study confirms applicability of so-called twice-slope method that is one of the limit analyses to evaluate llapse or plastic buckling, to cylindrical struc ture of core internals even when it has cracks. Three lindrical test specimens with radius to thickness ratio equivalent of core shroud were used for monotonic nding test with various condition of cracking to confirm applicability of twice-slope method. The other o specimens with duplicate condition of cracking and dif ferent range of loading were ...
英字タイトル:
Evaluation Method of Structural Integrity for Cylindrical Internal Structure with Cracks

Electronic Journal of Advanced Maintenance (EJAM) has been issued on the website of Japan Society of Maintenology (ISM) on May 25th, 2009. “New Technology' is one of the EJAM categories, and introduces widely advanced techniques developed or modified for maintenance. 'New Technology' has been created through discussion by members of the New Technology Committee, which is in the editorial organization of EJAM. In th at discussion, it was pointed out that people concerned with maintenance technology have no...
英字タイトル:
‘New Technology' of EJAM and Its Objective

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...
英字タイトル:
Guideline on Application Process of Techniques Developed for Maintenance Activities

“Guidelines for Inspection and Evaluation of Reactor Internals”, published by Thermal and Nuclear Power Engineering Society (TENPES) and taken over by Japan Nuclear Technology Institute (JANTI), adopted a very conservative assumption on flaw characterization for uninspected region of cylindrical components. Fully penetrated flaw should be assumed for uninspected region, when SCC is found and flaw evaluation is performed on cylindrical core internals such as core shroud. The authors suggested a modified me...
英字タイトル:
Technical Basis for Revision of Guidelines for Inspection and Evaluation of Reactor Internals on Flaw Characterization for Uninspected Region of Cylindrical Components