Development of safety injection flow map associated with target depressurization for effective severe accident management of OPR1000

Figures & data

Table 1. States of nuclear power plant recommended by IAEA [1].

Operational states	• Normal operation
	• Anticipated operational occurrences
Accident conditions	• Accident conditions which are not explicitly considered DBAs but which are encompassed by them.
	• DBAs
	• BDBAs without significant core degradation
	• Severe accidents

Figure 1. Flowchart of OPR1000 SAMG.

Table 2. A summary of severe accident analysis.

Authors	Reactor type	Analysis code	Objective
Vierow et al. [4]	Zion (WH 4 loop)	MELCOR, MAAP4, SCDAP/RELAP	Comparative calculation for TMLB accident analysis
Wang et al. [5]	Kuosheng and Maanshan NPP (BWR)	MELCOR, MAAP4, SCDAP/RELAP	Comparative calculation for LBLOCA and SBO accident analysis
Park and Hong [6]	OPR1000	SCDAP/RELAP	Analysis of SAMG entry condition
Park et al. [7]	OPR1000	SCDAP/RELAP	Analysis of RCS depressurization of SAMG for SBLOCA and TLOFW accidents
Park et al. [8]	OPR1000	SCDAP/RELAP	Analysis of coolant injection strategy of SAMG for SBLOCA and TLOFW accident
Huang et al. [9]	Kueosheng NPP (BWR)	MELCOR	Evaluation of feed and bleed strategy of SAMG
Martin-Fuertes et al. [10]	2700 MWt PWR and 1381 MWt BWR	MELCOR	Analysis of cavity flooding strategy of SAMG through comparison of lower head CHF correlation
Song et al. [11]	Ulchin 1&2 (Framaton PWR) and Kori 1(WH PWR)	MELCOR	Quantitative assessment of RCS depressurization and ERVC
Lee et al. [12]	OPR1000	MELCOR	Validation of RCS depressurization strategy and core coolability map
Seo et al. [13]	OPR1000	MELCOR	Effectiveness and adverse effects of RCS depressurization with various SAMG entry conditions
Stefanova et al. [14]	VVER 1000	ASTEC	Analytical validation of operator actions based on SAMG
Chatterjee et al. [15]	VVER 1000	ASTEC	Severe accident management strategy verification
Atanasova et al. [16]	VVER 1000	ASTEC	SBO calculations with PSRV stuck open

Figure 2. RCS SI flow map in OPR1000 SAMG.

Figure 3. MELCOR nodalization for OPR1000.

Figure 4. MELCOR nodalization for reactor core of OPR1000.

Table 3. Design value and steady-state condition of OPR1000.

Parameter	FSAR	MELCOR
Core thermal power (MWt)	2815	2815
RCS pressure (MPa)	15.5	15.5
Core inlet temperature (K)	569	573
Core outlet temperature (K)	600	603
Primary flow rate (kg/s)	15,306	15,546
Secondary side pressure (MPa)	7.37	7.37
Steam flow rate per SG (kg/s)	800	809

Table 4. Major accident sequences in the base case.

Accident sequence	SBLOCA	SBO	TLOFW
Accident start (hr)	0	0	0
Reactor trip (hr)	0.04	0	0.01 (1517 sec)
PSRV open (hr)	0	1.36	0.42
Steam generator dry out (hr)	1.74	1.04	0.27
Oxidation start (hr)	2.35	2.29	1.08
Cladding melting (hr)	2.64	2.65	1.36
Core dry out (hr)	2.72	2.62	1.40
UO2 relocation to lower head (hr)	2.89	2.83	1.56
SIT injection	3.64	3.80	2.33
SIT exhaust	5.89	3.94	2.40
RPV failure (hr)	5.82	3.78	2.30
Pressure at RPV failure (MPa)	5.42	16.22	16.62

Figure 5. Behavior of reactor core water level with respect to CET for base cases.

Figure 6. Behavior of RCS pressure for base cases.

Figure 7. Behavior of reactor core water level for base cases.

Figure 8. Behavior of CET for base cases.

Figure 9. Oxidation and decay heat generation during SBLOCA scenario.

Figure 10. Oxidation and decay heat generation during SBO scenario.

Figure 11. Oxidation and decay heat generation during TLOFW scenario.

Figure 12. A simplified reactor pressure vessel for SI flow model.

Figure 13. Characteristic pump curve by one and two HPSIs.

Figure 14. RCS SI flow map for SBLOCA scenario.

Figure 15. RCS SI flow map for SBO scenario.

Figure 16. RCS SI flow map for TLOFW scenario.

Table 5. The time of cladding melting and core recovery for the selected coolant injection.

CASE	Flow rate (m^3/sec)	Injection time (hr)	Cladding melting (hr)	Core recovery (hr)
SBLOCA-0.005	0.005	2.36	2.60	N/A
SBLOCA-0.015	0.015	2.36	2.60	N/A
SBLOCA-0.020	0.020	2.36	2.61	N/A
SBLOCA-0.025	0.025	2.36	N/A	3.03
SBO-0.005	0.005	2.25	2.56	N/A
SBO-0.015	0.015	2.25	2.59	N/A
SBO-0.020	0.020	2.25	N/A	10.06
SBO-0.025	0.025	2.25	N/A	2.99
TLOFW-0.005	0.005	1.08	1.30	N/A
TLOFW-0.015	0.015	1.08	1.31	N/A
TLOFW-0.025	0.025	1.08	1.41	N/A
TLOFW-0.028	0.028	1.08	N/A	1.78

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