蒸気発生器管板構造モデル試験解析報告書

Analysis report on test of tubesheet model of evaporator

笠原 直人; 堀切 守人; 岩田 耕司; 宇野 哲老*; 今津 彰; 戸倉 直*

Kasahara, Naoto; Horikiri, Morito; Iwata, Koji; Uno, Tetsuro*; Imazu, Akira; Tokura, Sunao*

高速炉の熱交換器等に見られる管板構造系は形状が複雑で強度評価が最も難しいものの1つである。本研究の目的はモデル試験データおよび詳細解析により原型炉用評価法の検証を行なうことと合理化のための知見を得ることである。3次元解析をもとに2次元の温度と応力解析モデルを開発し、試験データの解析を行なった。また試験と解析結果から設計評価法各部の検討を行なった。3次元解析からは熱過渡時の応力発生メカニズムが明らかになった。また応力要因に着目して開発した簡易温度解析モデルと3次元効果を考慮した2次元応力解析モデルは3次元解析の結果とよく一致した。簡易モデルを用いた温度試験解析からはシュラウド内側熱伝達面に管内乱流熱伝達式を適用した場合、保守的となることが分かった。またひずみ試験データ解析からは2次元非弾性解析結果は試験結果と数%の精度で一致し、設計評価法はこれらに比べ大きな裕度を持つことが分かった。結論として原型炉用の評価法は総合的には大きな裕度を持つ。その要因としてシュラウド部伝達係数の価小評価とひずみ集中係数の過大な裕度があげられる。しかしA-8000による穴まわり応力評価は裕度を持つとはいえない。

The structural design methods for tubesheets have been studied in connection with the development of fast breeder reactors, because tubesheet structures have complex and 3-dimmensional configulation, and are subjected to severe thermal loading. In Japan the tentative guidelines for structural design methods for tubesheets of FBR plants are proposed by the task group on the design methods of tubesheets in Power Reactor and Nuclear Fuel Development Corporation. The objective of this study is to validate this tentative methods by using data obtained from thermal transient tests of tubesheet models of evaporator and detailed analytical study, and moveover to provide usuful knowledge to rationalize the tentative guidelines. In this report, simplified methods of thermal and stress analyses for tubesheet structures are newly proposed and applied to thermal transient tests of tubesheet models which were carried out in 1984. The works contained in this report are summarized as; (1)Heat transfer analyses with 3-dimensional full model and elastic analyses with the same model are executed on the tubesheet structure, and the mechanism of thermal stress generation in the tubesheets is clarified. (2)Two simplified heat transfer analysis models are developed: the convection film model and the modified perforated plate model. Tbose models are proved to be accurate enough through the comparison with the results of 3-dimensional analyses. (3)Heat-transfer coefficient on the tubesheet structures are discussed with the data of temperature tests and thermal-hydraulicanalyses. As the results, it is shown that the film heat-transfer formula for turbulent flow inside tubes canbe used conservatively for inner surface of shrouds. (4)The simplified inelastic analysis method for tubesheets is developed. This method uses 2-dimensional models considering 3-dimensional effects of shrouds. As the results of comparison with the thermal transient test data of tubesheet model, the ...