LEAPコード用ブローダウンコードの改良

Improvement of blow down model for LEAP code

糸岡 聡*; 藤又 和博*

Itooka, Satoshi*; Fujimata, Kazuhiro*

高速炉の蒸気発生器における伝熱管破損事故に起因するナトリウム-水反応現象評価の高度化の一環として、高温ラプチャ型破損評価手法の更なる整備が進められ、限界熱流速とPost-CHF伝熱相関式に関する軽水炉研究の調査に基いて伝熱管内の冷却条件(管内熱伝達相関)の整理が実施された。 本作業では上述の管内冷却条件の整理を反映することを主目的として、次に示すLEAPコード用ブローダウンコードの改良を実施した。また、改良したLEAP-BLOWコードに対して機能確認のための適用計算を実施し、改良コードの妥当性を確認した。 ・限界熱流束(CHF)判定式(甲藤の式及びTongの式)の追加 ・Post-CHF伝熱相関式(Condie-Bengston IVの式及びGroeneveld 5.9の式)の追加 ・水・蒸気の物性値及び臨界流量計算モデルの圧力上限を水の臨界圧力まで拡張 ・考慮できる配管数及び総セクションの拡張と入力書式の変更 ・任意箇所の圧力を、PID制御による調節弁の弁開度により制御できる機能の追加

In Japan Nuclear Cycle Development Institute, the improvement of analysis method for overheating tube rapture was studied for the accident of sodium-water reactions in the steam generator of a fast breeder reactor and the evaluation of heat transfer condition in the tube were carried out based on study of critical heat flux (CHF) and post-CHF heat transfer equation in Light Water Reactors. In this study, the improvement of blow down model for the LEAP code was carried out taking into consideration the above-mentioned evaluation of heat transfer condition. Improvements of the LEAP code were following items. Calculations and verification were performed with the improved LEAP code in order to confirm the code functions. (1)The addition of critical heat flux (CHF) by the formula of Katto and the formula of Tong. (2)The addition of post-CHF heat transfer equation by the formula of Condie-Bengston Ⅳ and the formula of Groeneveld 5.9. (3)The physical properties of the water and steam are expanded to the critical conditions of the water. (4)The expansion of the total number of section and the improvement of the input form. (5)The addition of the function to control the valve setting by the PID control model.