Development of Double-Wall-Tube stream generator, 10; Evaluation of thermal hydraulic tests

Nakai, Satoru; Sato, Hiroyuki

The 1MW test model of double wall tube steam generator (DWTSG) was installed and experiments have been being carried out to evaluate the feasibility of DWTSG. Main objectives of this test are to evaluate DWTSG thermal hydraulic performance and to obtain basic data to be reflected to structural integrity of the double wall tube under steam generator circumstances such as DNB and flow instability and capability of leak detection. The evaluation of thermal hydraulic tests such as watcr single phase flow tests, two phase flow tests and boiling/super heated steam tests have been conducted. An accuracy of one dimensional thermal hydraulics analysis code, POPAI-6, has also been evaluated by the experimental data. Following results have been obtained. (1)As for the sodium side heat transfer coefficient, some modification of Graber-Rieger's correlation that was used at the DWTSG design is needed to adjust experimental data. Modification factor is 0.8. (2)Roko's and Kon'kov's DNB quality correlations can predict experimental results in 15% error. (3)The modification factor of Dittus-Boelter is 0.8 in pre-heat region. (4)The experimental heat transfer coefficicnt has a wide range and it is very difficult to derive an experimental correlation. (5)The modification factors of Bishop and Mod. Tong are 0.65 and 0.8 respectively in post dryout region. (6)The modification factors of Bishop and Dittus-Boelter are 0.73 and 0.58, respectively, in steam region. (7)At DNB point, the Jens-Lottes correlation gives conservativc heat transfer coefficient as a nucleate boiling and the Bishop correlation with abovc modification factor gives conservative heat transfer coefficient as post dry out heat transfer coefficient. (8)Experimental heat transfer correlation were derived besides nucleate boiling. (9)Both sodium and water/steam side temperature distribution is in a predicted at the normal operation. However the less or sodium/water flow rate ratio, the larger steam temperature ...