国際原子力機関主催「実炉データを用いた熱構造力学・熱流動解析コードの検証」研究プログラム(I)-仏国高速炉フェニックスでの高サイクル熱疲労事象に係わる熱流動ベンチマーク解析-

IAEA Coordinated research program on "Harmonization and validation of fast reactor thermomechanical and thermohydraulic codes using experimental data"(I); Thermohydraulic benchmark analysis on high-cycle thermal fatigue events occurred at french fast breeder reactor Phenix

村松 壽晴

not registered

国際原子力機関では、高速炉プラントの多くの部位で発生する流体温度ゆらぎによる高サイクル熱疲労 (サーマルストライピング) に対し、解析的評価手法開発の現状を把握するとともにその高度化を図ることを目的として、フランス高速原型炉フェニックスの2次主冷却系配管で発生した熱疲労事象を評価対象とした国際ベンチマーク演習が計画され、現在実施の段階にある。本報告書は、当該ベンチマーク演習問題の内、熱流動挙動に関する部分 (Phase-1)の解析を、直接シミュレーションコードDINUS-3および境界要素法コードBEMSETを用いて行った結果について報告するものである。この解析の結果、枝管から流出した高温ナトリウム噴流が主配管壁に沿って左右に振動しながら下流側に押し流される挙動が評価された。また、この噴流の両脇から概ね対称に下流側に広がる高温領域が再現され、これが目視観察による熱疲労変色領域と概ね一致することが確認された。

A benchmark exercise on "Tee junction of Liquid Metal Fast Reactor (LMFR) secondary circuit" was proposed by France in the scope of the said Coordinated Research Program (CRP) via International Atomic Energy Agency (IAEA). The physical phenomenon chosen here deals with the mixture of two flows of different temperature. ln a LMFR, several areas of the reactor are submitted to this problem. They are often difficult to design, because of the complexity of the phenomena involved. This is one of the major problems of the LMFRs. This problem has been encountered in the Phenix reactor on the secondaly loop, where defects in a tee junction zone were detected during a campaign of inspections after an operation of 90,000 hours of the reactor. The present benchmark is based on an industrial problem and deal with thermal striping phenomena. Problems on pipes induced by thermal striping phenomena have been observed in some reactors and experimental facilities coolant circuits. This report presents numerical results on thermohydraulic characteristics of the benchmark problem, carried out using a direct numerical simulation code DINUS-3 and a boundary element code BEMSET. From the analysis with both the codes, it was confirmed that the hot sodium from the small pipe rise into the cold sodium of the main pipe with thermally instabilities. Furthermore, it was indicated that the coolant mixing region including the instabilities agrees approximately with the result by eye inspections.