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Journal Articles

Effects of secondary depressurization on core cooling in PWR vessel bottom small break LOCA experiments with HPI failure and gas inflow

Suzuki, Mitsuhiro; Takeda, Takeshi; Asaka, Hideaki; Nakamura, Hideo

Journal of Nuclear Science and Technology, 43(1), p.55 - 64, 2006/01

 Times Cited Count:10 Percentile:38.42(Nuclear Science & Technology)

Effects of non-condensable gas from the accumulator tanks on secondary depressurization, as one of accident management (AM) measures in case of high pressure injection system failure, are studied at the ROSA-V/LSTF experiments simulating a ten instrument-tube break LOCA at the PWR vessel bottom. In an experiment with no gas inflow, the secondary depressurization at -55 K/h initiated by SI signal with 10 minutes delay succeeded in the LPI actuation. On the other hand, the gas inflow in another experiment degraded the primary depressurization and resulted in core uncovery before the LPI start. The third experiment with rapid secondary depressurization and continuous auxiliary feedwater supply, however, showed a possibility of long-term core cooling by the LPI actuation. RELAP5/MOD3 code analyses well predicted these experiment results and clarified that condensation heat transfer was largely degraded by the gas in the U-tubes. In addition, a primary pressure - coolant mass map was found to be useful for indication of key plant parameters of AM measures.

JAEA Reports

Experimental study on secondary depressurization action for PWR vessel bottom small break LOCA with HPI failure and gas inflow (ROSA-V/LSTF test SB-PV-03)

Suzuki, Mitsuhiro; Takeda, Takeshi; Asaka, Hideaki; Nakamura, Hideo

JAERI-Research 2005-014, 170 Pages, 2005/06

JAERI-Research-2005-014.pdf:7.64MB

A small break LOCA (SBLOCA) experiment was conducted at the LSTF of ROSA-V program to study effects of accident management (AM) on core cooling, which is important in case of high pressure injection (HPI) system failure during an SBLOCA at a PWR. The experiment, SB-PV-03, simulated ten instrument-tube break LOCA at the PWR vessel bottom equivalent to 0.2% cold leg break, total HPI failure, non-condensable gas inflow from accumulator injection system (AIS) and AM actions on secondary depressurization at -55 K/h and auxiliary feedwater (AFW) supply for 30 minutes. It was clarified that the AM actions were effective on primary depressurization until AIS injection end at 1.6 MPa, but thereafter became less effective by the gas inflow, resulting in low pressure injection (LPI) delay and whole core heatup under continuous water discharge at the break. The report describes these phenomena including core heatup related with primary coolant mass and AM actions, primary-to-secondary heat transfer analysis and estimation of gas in the primary loops.

Journal Articles

Effects of secondary depressurization on PWR bottom small break LOCA experiments in case of HPI failure and non-condensable gas inflow

Suzuki, Mitsuhiro; Takeda, Takeshi; Asaka, Hideaki; Nakamura, Hideo

Proceedings of 6th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operations and Safety (NUTHOS-6) (CD-ROM), 14 Pages, 2004/10

no abstracts in English

Journal Articles

Analysis of pressure- and temperature- induced steam generator tube rupture during PWR severe accident initiated from station blackout

Hidaka, Akihide; Maruyama, Yu; Nakamura, Hideo

Proceedings of 6th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operations and Safety (NUTHOS-6) (CD-ROM), 15 Pages, 2004/00

Severe accident studies showed that Direct Containment Heating issue was resolved for PWRs because a creep rupture at pressurizer surge line would occur prior to the melt-through of Reactor Pressure Vessel during station blackout (TMLB'). However, it was recently concerned that, if the secondary system is depressurized during TMLB', the creep rupture at SG U-tubes would occur earlier than the surge line. This pressure- and temperature-induced SG U-tube rupture (PTI-SGTR) is not preferable because of the increase in offsite consequences. The SCDAP/RELAP5 analyses by USNRC showed that the surge line would fail earlier than the U-tubes. However, the analyses used a coarse nodilization for steam mixing at the SG inlet plenum that could affect the temperature of U-tubes. To investigate the effect of steam mixing, an analysis was performed with MELCOR1.8.4. The analysis showed that the surge line would fail earliest during TMLB' while the U-tubes could fail earliest during TMLB' with secondary system depressurization. Further investigation is needed for occurrence conditions of PTI-SGTR.

Journal Articles

Study of accident management measures for prevention of severe core damage in ROSA-V program

Asaka, Hideaki; Anoda, Yoshinari

Konsoryu, 17(2), p.116 - 125, 2003/06

no abstracts in English

Journal Articles

Thermal hydraulic research on next generation PWR's using ROSA/LSTF

Yonomoto, Taisuke; Anoda, Yoshinari

IAEA-TECDOC-1149, p.233 - 246, 2000/05

no abstracts in English

JAEA Reports

ROSA/LSTF experiment report for RUN SB-CL-24; Repeated core heatup phenomena during 0.5% cold leg break

Suzuki, Mitsuhiro; Anoda, Yoshinari

JAERI-Tech 2000-016, p.173 - 0, 2000/03

JAERI-Tech-2000-016.pdf:7.25MB

no abstracts in English

Journal Articles

Core liquid level responses due to secondary-side depressurization during PWR small break LOCA

Asaka, Hideaki; ; Anoda, Yoshinari; Onuki, Akira; Kukita, Yutaka*

Journal of Nuclear Science and Technology, 35(2), p.113 - 119, 1998/02

 Times Cited Count:10 Percentile:34.21(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Thermal-hydraulic characteristics of a next-generation reactor relying on steam generator secondary side cooling for primary depressurization and long-term passive core cooling

Yonomoto, Taisuke; ; Anoda, Yoshinari

Nucl. Eng. Des., 185(1), p.83 - 96, 1998/00

 Times Cited Count:3 Percentile:66.54(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Intentional depressurization of steam generator secondary side during a PWR small-break loss-of-coolant accident

; Kukita, Yutaka

Journal of Nuclear Science and Technology, 32(2), p.101 - 110, 1995/02

 Times Cited Count:16 Percentile:17.8(Nuclear Science & Technology)

no abstracts in English

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