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Journal Articles

Major outcomes through recent ROSA/LSTF experiments and future plans

Takeda, Takeshi; Wada, Yuki; Shibamoto, Yasuteru

World Journal of Nuclear Science and Technology, 11(1), p.17 - 42, 2021/01

Journal Articles

ROSA/LSTF test on nitrogen gas behavior during reflux condensation in PWR and RELAP5 code analyses

Takeda, Takeshi; Otsu, Iwao

Mechanical Engineering Journal (Internet), 5(4), p.18-00077_1 - 18-00077_14, 2018/08

Journal Articles

ROSA/LSTF tests and posttest analyses by RELAP5 code for accident management measures during PWR station blackout transient with loss of primary coolant and gas inflow

Takeda, Takeshi; Otsu, Iwao

Science and Technology of Nuclear Installations, 2018, p.7635878_1 - 7635878_19, 2018/00

 Times Cited Count:2 Percentile:61.42(Nuclear Science & Technology)

Journal Articles

RELAP5 uncertainty evaluation using ROSA/LSTF test data on PWR 17% cold leg intermediate-break LOCA with single-failure ECCS

Takeda, Takeshi; Otsu, Iwao

Annals of Nuclear Energy, 109, p.9 - 21, 2017/11

 Times Cited Count:4 Percentile:44.27(Nuclear Science & Technology)

Journal Articles

ROSA/LSTF test and RELAP5 analyses on PWR cold leg small-break LOCA with accident management measure and PKL counterpart test

Takeda, Takeshi; Otsu, Iwao

Nuclear Engineering and Technology, 49(5), p.928 - 940, 2017/08

 Times Cited Count:3 Percentile:54.72(Nuclear Science & Technology)

Journal Articles

ROSA/LSTF test on nitrogen gas behavior during reflux cooling in PWR and RELAP5 post-test analysis

Takeda, Takeshi; Otsu, Iwao

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 11 Pages, 2017/07

Journal Articles

ROSA/LSTF experiment on a PWR station blackout transient with accident management measures and RELAP5 analyses

Takeda, Takeshi; Otsu, Iwao

Mechanical Engineering Journal (Internet), 2(5), p.15-00132_1 - 15-00132_15, 2015/10

Journal Articles

Thermal hydraulic safety research at JAEA after the Fukushima Dai-ichi Nuclear Power Station accident

Yonomoto, Taisuke; Shibamoto, Yasuteru; Takeda, Takeshi; Satou, Akira; Ishigaki, Masahiro; Abe, Satoshi; Okagaki, Yuria; Sun, Haomin; Tochio, Daisuke

Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), p.5341 - 5352, 2015/08

Journal Articles

RELAP5 code study of ROSA/LSTF experiments on PWR safety system using steam generator secondary-side depressurization

Takeda, Takeshi; Onuki, Akira*; Nishi, Hiroaki*

Journal of Energy and Power Engineering, 9(5), p.426 - 442, 2015/05

Journal Articles

ROSA/LSTF experiment on AM measures during a PWR station blackout transient with pump seal leakage and RELAP5 POST-TEST analysis

Takeda, Takeshi; Otsu, Iwao

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 10 Pages, 2015/05

Journal Articles

RELAP5 code study of ROSA/LSTF validation tests for PWR safety system using SG secondary-side depressurization

Takeda, Takeshi; Onuki, Akira*; Nishi, Hiroaki*

Proceedings of 10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10) (USB Flash Drive), 13 Pages, 2014/12

Journal Articles

RELAP5 analyses of ROSA/LSTF experiments on AM measures during PWR vessel bottom small-break LOCAs with gas inflow

Takeda, Takeshi

International Journal of Nuclear Energy, 2014, p.803470_1 - 803470_17, 2014/00

JAEA Reports

Analysis on non uniform flow in steam generator during steady state natural circulation cooling

Susyadi; Yonomoto, Taisuke

JAERI-Research 2005-011, 64 Pages, 2005/06

JAERI-Research-2005-011.pdf:2.57MB

Steady-state natural circulation (NC) in the PWR was investigated focusing on non uniform flow among steam generator (SG) U-tubes observed in the ROSA/LSTF experiments. In the analysis using the RELAP5/MOD3 code, the SG behavior was analyzed using the partial SG model with one, five, or nine parallel flow paths in the primary side and boundary conditions based on the experiments. The results showed that simulations using the model with five or nine tubes were capable to capture important non uniform phenomena such as reverse flow, fill and dump and stagnant vertical stratification, and the stable SG outlet flow as observed in the experiments. Heat transfer rates to the secondary side were, however, underpredicted by up to 15%. Furthermore, difficulties were found in establishing the steady state condition especially for the low pressure analysis: only when the inlet flow rate was carefully imposed, stable NC behavior was obtained.

Journal Articles

ROSA/LSTF experiments on low-pressure natural circulation heat removal for next-generation PWRs

Yonomoto, Taisuke; Otsu, Iwao

Proceedings of 12th Pacific Basin Nuclear Conference (PBNC 2000), Vol.1, p.317 - 329, 2000/00

no abstracts in English

Oral presentation

ROSA/LSTF test on PWR station blackout transient and RELAP5 analyses

Takeda, Takeshi; Otsu, Iwao

no journal, , 

An experiment on accident management (AM) measures during a PWR station blackout transient with leakage from primary coolant pump seals was conducted using the ROSA/large scale test facility (LSTF) based on the Fukushima accident. Through RELAP5/MOD3.2 code, we investigate core void fraction and surface heat transfer coefficient of the cladding. In addition, sensitivity analyses were performed with the RELAP5 code. The onset timing of SG secondary depressurization as well as the SG coolant injection flow rate were found to significantly affect the peak cladding temperature.

Oral presentation

ROSA/LSTF test on nitrogen gas behavior during reflux cooling and RELAP5 analysis

Takeda, Takeshi; Otsu, Iwao

no journal, , 

The primary coolant inventory may affect degradation in the primary depressurization due to failure of accumulator system isolation in PWR accidents. A separate-effect experiment with the ROSA/LSTF was thus conducted focusing on nitrogen gas behavior under reflux cooling condition at low pressures. The test showed primary pressure and flow behavior in steam generator (SG) U-tubes were dependent on amount of the gas accumulated. In addition, RELAP5/MOD3.3 code indicated remaining problems in the predictions of the primary pressure and SG U-tube fluid temperature after the nitrogen gas inflow.

Oral presentation

ROSA/LSTF test on PWR station blackout transient with loss of primary coolant and RELAP5 analysis

Takeda, Takeshi; Otsu, Iwao

no journal, , 

The effectiveness of accident management measure should be confirmed in case of PWR station blackout transient with loss of primary coolant. A simulation experiment with the ROSA/LSTF was thus conducted under an assumption of nitrogen gas inflow into the primary system. After the nitrogen gas inflow, the primary depressurization rate became smaller and non-uniform flow behavior was observed among steam generator (SG) U-tubes. In addition, RELAP5/MOD3.2 code indicated remaining problems in the predictions of the primary pressure and SG U-tube liquid level after the nitrogen gas inflow through the post-test analysis.

Oral presentation

Sensitivity analysis with RELAP5 code using ROSA/LSTF test data on steam generator tube rupture

Takeda, Takeshi; Otsu, Iwao

no journal, , 

Post-test analysis with RELAP5/MOD3.3 code was performed for ROSA/LSTF test on PWR steam generator (SG) tube rupture. The code predicted such main phenomena as different natural circulation between two loops, while it indicated remaining problems in the predictions of broken SG secondary pressure after intact SG depressurization. The sensitivity analysis results found the number of SG tubes with double-ended guillotine break and actuation of high-pressure injection system of emergency core cooling system affect primary and secondary pressures and so forth.

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