Kaliopa Mancheva. Reliability, Safety and Management Engineering and Software Development Services

Transcription

1 Kaliopa Mancheva Reliability, Safety and Management Engineering and Software Development Services

2 o SFP model o Results from calculations o Problems and questions 2

3 o SFP model was developed as part of PSA level 2 study for unit 5 and 6 of KNPP o 5 accident scenarios taken from PSA level 1: Scenario Containment status Cooling system (TG) Alternative cooling system (SS, TB30, 0TM) Spray System 1 Isolated Failed Failed Up to tank depletion 2 Isolated Failed Failed 3 Isolated Failed Up to tank depletion Failed Failed 4 Not Isolated Failed Failed Failed 5 Not Isolated Failed Up to tank depletion Failed 3

4 Real configuration SFP Rack 4

5 o DATA: Reactor type SFP-BWR FAnumber-563 Control rods B 4 C difference from reactor ( 10 B included in rack steel) Lowerhead flat All racks are occupied with FA(163 from reactor core) Axial power profile - uniform 9-th day after reactor shutdown Water level 28,8 m (about 2,5maboveracks) Fuel assembly distribution 5

6 C o m m o n p a r t C V 9 0 C o n c r e te w a ll C V 9 1 C V 9 2 R I N G 1 R I N G 2 R IN G 3 R IN G 4 B Y P A S S C V C V 8 1 C V C V 8 3 C V C V C V 8 6 C V C V C V C V 7 1 C V C V 7 3 C V C V 7 5 C V C V C V C V C V 6 1 C V C V 6 3 C V C V 6 5 C V C V C V C V C V 5 1 C V C V 5 3 C V C V 5 5 C V C V C V C V C V 4 1 C V C V 4 3 C V C V 4 5 C V C V C V C V C V 3 1 C V C V 3 3 C V C V 3 5 C V C V C V C V 2 1 C V 2 0 6

7 o o Radial rings: 1 ring 163 assemblies (assemblies removed from reactor Qw> 1.00E4 [W]) 2 ring 149 assemblies (1.00E3 Qw 3.00E3 [W]) 3 ring 125 assemblies (Qw 1.00E3 [W]) 4 ring 126 assemblies (3.00E3 Qw 1.00E4 [W]) 5 ring outer volumes (free of assemblies) Axial distribution: 1 7(support construction) 8,19 and20 (1 lower and2 upper unheated core part) 9 18 (heated core part) 7

8 Lower elevation Height UPPER_1 UPPER_2 UPPER_3 UPPER_4 UPPER_ BOK_15 Unheated core part BOK_ BOK_ BOK_ BOK_ BOK_ BOK_ BOK_ BOK_ BOK_ BOK_ BOK_ BOK_3 Unheated core part plate 207 plate 307 plate 407 plate 507 plate BOK_2 Heated core part plate plate plate plate 506 BOK_1 505 plate CV020 8

9 o Cavity 1 volume of the smaller pool volume CV488 connected to cavity 1 simulates ring 1 + bypass part o Cavity 2 : Represents partially volume of the bigger pool same volume as for LP is used (CV020) Spreading model of debris o Dependent failure of the support structures in bigger pool is simulated based on the debris surface(cav_asurf) 9

10 o Cavity 3 the containment rooms bellow SFP o Cavity 4 volume of the transport corridor -activates in case of transport hatch failure IV III II I 10

11 36 34 CFVALU_20 32 Ниво [m] Inner wall failure Water Level in smaller pool o Water in smaller pool (ring 1) evaporates first o Water in bigger pool is ejected after inner wall failure Level [m] ejection evaporation ejection CFVALU_21 Time [s] Water Level in bigger pool 11

12 2500 Температура [ K] COR-TCL_108 COR-TCL_109 COR-TCL_110 COR-TCL_111 COR-TCL_112 COR-TCL_113 COR-TCL_114 COR-TCL_115 COR-TCL_116 COR-TCL_117 COR-TCL_118 COR-TCL_119 Clad failure by CF actuation o o Clad temperatures in smaller pool Fuelassemblies in ring 1 (smaller pool) fails by temperature criterion Fuel assemblies in ring 2-4 (bigger pool) fails due to support column failure Температура [ K] COR-TCL_208 COR-TCL_209 COR-TCL_210 COR-TCL_211 COR-TCL_212 COR-TCL_213 COR-TCL_214 COR-TCL_215 COR-TCL_216 COR-TCL_217 COR-TCL_218 COR-TCL_219 Clad temperatures in bigger pool ring 2

13 COR-DMH2-TOT CAV-MEX-H2_10 CAV-MEX-H2_20 o Hydrogen generation is not significantly less than in reactor Маса [kg] CAV-MEX-H2_ Hydrogen generation COR and CAV Маса [kg] CAV-MEX-CO_10 CAV-MEX-CO_20 CAV-MEX-CO_30 o CO generation is an issue in KNPP due to concrete chemical composition CO generation - CAV 13

14 Маса [kg] CAV-MTOT_10 CAV-MTOT_20 CAV-MTOT_30 Радиус на разстилане [m] CAV-MAXRAD_10 CAV-MAXRAD_20 CAV-MAXRAD_ Debris mass in cavities o SFP outer walls failure about 2.3 days (55 hours) o Very slow radial ablation debris temperature is low (1540 K) Височина [m] 2 Concrete ablation - radial CAV-MINALT_10 12 CAV-MINALT_20 CAV-MINALT_ Concrete ablation - axial 14

15 CVH-P_ Нaлягане [Pa] Температура [ K] CVH-TVAP_472 CVH-TVAP_ Containment pressure 300 Containment temperature 1 o Containment pressure meet failure criteria at 10.4 days o Atmosphere temperature < 200 C o Flammable gas concentrations 41 hours after IE Концентрация [-] CVH-X.3_472 CVH-X.4_472 CVH-X.5_472 CVH-X.6_472 CVH-X.8_472 4% H2 12% CO 55% Пара 0 Containment gas composition 15

16 o?wwer SFP are divided into 3 main pools (4-th one is for fresh fuel) o? Simulation of debris interaction with solid structures after inner wall failure o? Non-supporting structures are forbidden for SFP- BWR o B 4 C oxidation problem run failure (bug 1088) o Cavity overfilled overcome with time step change. This behaviour of the model stays unresolved 1

17 TRANSFER PROCESS EDIT NUMBER OF IN TRANSFER PROCESSES = 8 IN TP NUMBER OF NUMBER OF H IN -H OUT MASSES IN THERMO IN (J) 101-A E B E A E B E A E B E A E B E+00 IN TP MATL MASS IN - MASS OUT NUMBER (KG) 101-A E E E E E E+02 Example of cavity overfilled problem IN TP MATL MASS IN - MASS OUT NUMBER (KG) 101-B E E E E E E E E E E E E E E E E E+00 The mass out is much more than mass in (MELCOR 4877 release) 17

18 Headquarters: 10, Vihren str. Sofia 1618 Bulgaria Tel Fax: riskeng@riskeng.bg 18

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