Forschungszentrum Karlsruhe Technik und Umwelt IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting :...

Forschungszentrum KarlsruheTechnik und Umwelt

IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Bologna, May 28-29, 2008 1

EFIT-Pb Transient AnalysisEFIT-Pb Transient Analysis

M. Schikorr, E. BubelisM. Schikorr, E. Bubelis

EUROTRANS: DM1 WP1.5 : “Safety”

Bologna , 28-29 Mai 2008



1. Recent EFIT-Pb SA design modifications leading to revised Core and Primary System Pressure Drops (Genova-April, Karlsruhe-April meetings, new Ansaldo document-May).

2. SIM-ADS Transient Results for EFIT-Pb :

a. ULOF results (BOC, EOC)

b. DHRS mode operations

c. PLOHS

Topics:



1. EFIT Pressure Drops: Historical evolution

1. Initial Pressure drop estimates :

P_core ~ 0.6 bar, P_prim. system ~ 1.0 bar,

2. 1st Iteration based on experimental PDS-XADS SA-inlet and SA-outlet pressure drops(Genova Meeting April 08),

Pressure drop estimates :


3. Most current pressure drop estimates after SA redesign by ANSALDO:


this will lead to a w_nat ~ 0.31 during ULOF(ss)



1. EFIT Pressure Drops: as proposed by Ansaldo after SA redesign leading to lower SA inlet and outlet pressure drops.

Ansaldo calculated pressure drops [14], mbar

Corresponding pressure drop coefficients (based on

coolant flowrate of 185 kg/s per SA)

SA Inlet 289 5.50 SA Outlet 86 1.64 Flow along smooth pin section

165

Grid spacers (6) * 94.4 Total core pressure drop 634.4 Total core pressure drop taking into account ~10 % uncertainty

700

Main HX (SG) [15] 400 7.61 Main pump [15] 270 5.16 Total pressure drop of the whole primary system

1370



2. EFIT Pressure Drops: as proposed to be used in Transient Calcs.Reactor core zone

Inner core zone CZ1

Intermediate core zone CZ2

Outer core zone CZ3

Power, [MW]

94 140 141

Average SA coolant flowrate, [kg/s]

192 182 168

Core flow friction pressure drop, [mbar]

172 156 225

6 Grid spacers pressure drop, [mbar]

101 92 112

Inlet / Outlet pressure drop, [mbar]

408 367 407

Gagging (orificing) pressure drop, [mbar]

63 129 0

Total core pressure drop, [mbar]

744 744 744

Calculated Zeta factor (Ratio of primary system pressure loss / core pressure loss) Zeta = 1.893 (Zeta = pprim syst / pcore = 1420 mbar / 750 mbar = 1.893) Total primary system pressure drop, [mbar]

1409 1409 1409



EFIT-Pb: Avg and Peak Cladding and Fuel Temperatures at Nominal and ULOF-ss Plant Conditions for BOC and EOC based on new Pressure Drop data (1.42 bar)

Clad Fuel Clad Fuel Clad Fuel Clad Fuel Clad Fuel Clad FuelNominal Conditions BOL 0 µm 505 1162 530 1284 502 1186 519 1262 496 1080 531 1271

EOC 0 µm 506 822 540 1003 503 831 523 938 496 784 525 931

EOC 50 µm 528 863 570 1062 525 871 549 988 513 818 546 978

ULOF Conditions BOL 0 µm 723 1409 700 1379 733 1400

EOC 0 µm 744 1222 709 1129 720 1128

EOC 50 µm 773 1275 732 1176 741 1171

Oxide Layer thickness

EFIT - Pb : Peak Fuel and Cladding Temperatures [°C]

Outer Core Zone CZ3

Avg Pin Peak PinAvg Pin Peak Pin

Inner Core Zone CZ1 Intermediate Core Zone CZ2

Avg Pin Peak Pin

Nominal Conditions BOL 0 µm

EOC 0 µm

EOC 50 µm

ULOF Conditions BOL 0 µm

EOC 0 µm

EOC 50 µm

E8 E8 E9

Oxide Layer thickness

Inner Core Zone CZ1 Intermediate Core Zone CZ2 Outer Core Zone CZ3

EFIT - Pb : Cladding Failure Times [hrs]

Avg Pin Peak Pin Avg Pin Peak Pin Avg Pin Peak Pin

E10

E7

E6

E9

E11 E12

E9

1.8xE3

3.8

1.2

E7

E6

E10E10

E7

E5

E11

E9

3.4XE3

2.8

1.7xE4

23.2

0.6 5.8



EFIT-Pb: CZ1 Inner Zone

Core averaged Avg. Pin

BOL

MgO-MOX fuel

Static Calculations

Ax_mult 1.000678536B 34.7651 cm Qcore 94.00 MWth Max_T_fuel 1162 3.41 Mpunktcore 8048.22 kg/secCosine-Ax 1 CHI_peak 169.3 W/cm Max_T_f_avg 963 4.48 Pump :Tein 400 grd CHI_peak 168.3 W/cm Max_T_f_surf 765 8.8 Pump_act 0.135 MWDT 80.0 grd Pin/Fuel Properties Data: Max T clad 505 44.6 P_pump_100 0.135 MWTaus 480.0 grd kclad 0.218 [W/cmK] 753.2 P_blower_100 0.135 MW

Chi_ist_dist 148.02 W/cm k_fuel 0.0353 [W/cm*K] T_cool_out 480.0 44.6 NUSSELT-Flag 0 Subbotin(tube)

Chi_ist_cos 148.03 W/cm hgap 0.2700 -21.0 Av_T_cool 439.9 -0.54 Dpgitter 0.10133 barCHI0 148.02 W/cm hs_av 1.5872 [W/cm^2K] Av_T_f_eff 832.9 Dpbeschl 0.47126 bar

flow_fr 1.000 flow fraction Av_T_fuel_center 1067.2 -23.5 Dpcore 0.17185 barPein 10 bar kfuel_fact 1.000 [factor] Av_T_f_avg 899.9 -22.41 Dptotal 0.74444 barP_fr 1.000 power fraction hgap_fact 1.000 28.1 Av_T_f_surf 732.5 -19.9 Dpsystem 1.40922 barPump_fr 1.0000 pump fraction hs_fact 1.000 [factor] Av_T_clad_surf 474.2 -5.6 (rho*vel^2)/2 5651 pascal

w 8048.22 kg/sec temp_drops: DP_core 0.17185 0.040w 8048.23 kg/sec delT_fuel_av 336.1 C DP_core_100 0.172 barMpunkt 1.14E+00 kg/sec/Pin delT_gap_av 244.0 C DP_system 1.40922 barMpunkt_100 1.14E+00 kg/sec/Pin delT_clad_av 15.2 C DP_boyancy 3468 pascal

Vpunktcore 7.65E+05 cm^3/sec Clad_failure inf hrs @ 100 bar delT_cl_cool_av 34.4 C 3468 3468

Design Pb -cooled Reactor : EFIT BOL Inner Core Zone 1

EFIT-Pb CZ1 BOL Axial Temperature Profile, Average Pin 148 W/cm

474

440480

505

1067

900963

733765

1162

400

500

600

700

800

900

1000

1100

1200

-45 -35 -25 -15 -5 5 15 25 35 45

Axial Core Position [cm]

Tem

per

atu

res

[°C

]

Clad surf

Coolant

Center Fuel

Surf Fuel

Avg Fuel

Fission Gas Model X_He 0.980 frX_Kr 0.001 frX_Xe 0.019 frk_He 2.64E-03 W/mK

k_Kr 8.25E-05 W/mK

k_Xe 4.35E-05 W/mKgap_eps 4.0.E-06 m

T_gas 611 °CP_pin_gas 2.7Gap fraction 0.702 EFIT-Pb

MWd/kg BOL avg

Burn_avg_pin 1 1.0Burn 1.0 0.1

Rel_gas_fr 1.00 EOL peak-burnMA_fr MOX_fract

0.543 0.43



EFIT-Pb: CZ2 Intermediate Zone


BOL

MgO-MOX fuel

Static Calculations





w 11986.72 kg/sec temp_drops: DP_core 0.15646 0.040w 11986.72 kg/sec delT_fuel_av 350.4 C DP_core_100 0.156 barMpunkt 1.08E+00 kg/sec/Pin delT_gap_av 236.5 C DP_system 1.40919 barMpunkt_100 1.08E+00 kg/sec/Pin delT_clad_av 14.5 C DP_boyancy 3468 pascal


Design Pb -cooled Reactor : EFIT BOL Inter Core Zone 2


473

440480

502

1072

898973

723761

1186

400

500

600

700

800

900

1000

1100

1200

1300

-45 -35 -25 -15 -5 5 15 25 35 45


Tem

per

atu

res

[°C

]

Clad surf

Coolant

Center Fuel

Surf Fuel

Avg Fuel


k_Kr 8.25E-05 W/mK



MWd/kg BOL avg



0.543 0.50



EFIT-Pb: CZ3 Outer Zone


BOL

MgO-MOX fuel

Static Calculations





w 12072.34 kg/sec temp_drops: DP_core 0.22537 0.040w 12072.34 kg/sec delT_fuel_av 306.4 C DP_core_100 0.225 barMpunkt 9.98E-01 kg/sec/Pin delT_gap_av 199.2 C DP_system 1.40917 barMpunkt_100 9.98E-01 kg/sec/Pin delT_clad_av 11.9 C DP_boyancy 3468 pascal


Design Pb -cooled Reactor : EFIT BOL Outer Core Zone 3


464

440480

496

980

827893

674707

1080

400

500

600

700

800

900

1000

1100

1200

-45 -35 -25 -15 -5 5 15 25 35 45


Tem

per

atu

res

[°C

]

Clad surf

Coolant

Center Fuel

Surf Fuel

Avg Fuel

Fission Gas ModelX_He 0.976 frX_Kr 0.001 frX_Xe 0.022 frk_He 2.64E-03 W/mK

k_Kr 8.25E-05 W/mK



MWd/kg BOL avg



0.543 0.50



EFIT-Pb: CZ1 Inner Zone


EOC

MgO-MOX fuel

Static Calculations

Ax_mult 1.01307632 1.) push "init", reset flow_fr E11 to 1.0, push "init" again. Repeat procedure until convergence is achieved in flow rate wB 38.5828 cm Qcore 94.00 MWth Max_T_fuel 863 7.35 Mpunktcore 8048.22 kg/secCosine-Ax 1 CHI_peak 167.3 W/cm Max_T_f_avg 708 10.58 Pump :Tein 400 grd CHI_peak 166.3 W/cm Max_T_f_surf 558 24.6 Pump_act 0.135 MWDT 80.0 grd Pin/Fuel Properties Data: Max T clad 528 34.6 P_pump_100 0.135 MWTaus 480.0 grd kclad 0.218 [W/cmK] 753.2 P_blower_100 0.135 MW

Chi_ist_dist 148.02 W/cm k_fuel 0.0442 [W/cm*K] T_cool_out 480.0 44.6 NUSSELT-Flag 0 Subbotin(tube)Chi_ist_cos 148.03 W/cm hgap 3.9148 -13.1 Av_T_cool 439.9 -0.54 Dpgitter 0.10133 barCHI0 148.02 W/cm hs_av 0.8849 [W/cm 2̂K] Av_T_f_eff 613.5 Dpbeschl 0.47126 bar

flow_fr 1.000 flow fraction Av_T_fuel_center 800.2 -19.5 Dpcore 0.17185 barPein 10 bar kfuel_fact 1.000 [factor] Av_T_f_avg 666.8 -17.39 Dptotal 0.74444 barP_fr 1.000 power fractionhgap_fact 1.000 44.6 Av_T_f_surf 533.4 -10.9 Dpsystem 1.40922 barPump_fr 1.0000 pump fraction hs_fact 1.000 [factor] Av_T_clad_surf 501.5 -8.1 (rho*vel 2̂)/2 5651 pascal

w 8048.22 kg/sec temp_drops: DP_core 0.17185 0.040w 8048.22 kg/sec delT_fuel_av 267.9 C DP_core_100 0.172 barMpunkt 1.14E+00 kg/sec/Pin delT_gap_av 16.9 C DP_system 1.40921 bar

kg/s per SA 191.6 Mpunkt_100 1.14E+00 kg/sec/Pin delT_clad_av 15.2 C DP_boyancy 3468 pascal

Vpunktcore 7.65E+05 cm 3̂/sec Clad_failure inf hrs @ 100 bardelT_cl_cool_av 61.8 C 3468 3468

Design Pb -cooled Reactor : EFIT EOC Inner Core Zone 1

EFIT-Pb CZ1 EOC Axial Temperature Profile, Average Pin 148 W/cm, 50mm Oxide

501

440480

528

800

667708

533558

863

400

450

500

550

600

650

700

750

800

850

900

-45 -35 -25 -15 -5 5 15 25 35 45


Tem

per

atu

res

[°C

]

Clad surf

Coolant

Center Fuel

Surf Fuel

Avg Fuel


k_Kr 8.25E-05 W/mK



MWd/kg EOC avg

Burn_avg_pin 66.5 66.5Burn 66.5 7.1


0.543 0.43

dL 3.70 m

grav 9.81 m/s 2̂Zeta 1.893P_min 0.3 barP_mult1 1N_Rey_trans 1187.4N_Rey_up 5000

alph_turb 0.0791 Blasiusbeta_turb 0.25 Blasiusalph_lam 16beta_lam 1 TurbulentN_Rey_aver 71286 Forced conv.f_weight 0.0048 70828w_nat 1262.68 kg/sw_nat_fr 0.157(w - w_nat) 6785.55K_orf 1.101 1.418K_inlet 5.50 core inlet friction coefficient

K_outlet 1.64 core outlet friction coeff



EFIT-Pb: CZ2 Intermediate Zone


EOC

MgO-MOX fuel

Static Calculations


k_Kr 8.25E-05 W/mK



MWd/kg EOC avg



0.543 0.50


499

440480

525

797

663711

530555

871

400

450

500

550

600

650

700

750

800

850

900

-45 -35 -25 -15 -5 5 15 25 35 45


Tem

per

atu

res

[°C

]

Clad surf

Coolant

Center Fuel

Surf Fuel

Avg Fuel

dL 3.70 m

Ax_mult 0.98687607 1.) push "init", reset flow_fr E11 to 1.0, push "init" again. Repeat procedure until convergence is achieved in flow rate w grav 9.81 m/s 2̂B 31.0480 cm Qcore 140.00 MWth Max_T_fuel 871 5.92 Mpunktcore 11986.72 kg/sec Zeta 1.893Cosine-Ax 1 CHI_peak 162.7 W/cm Max_T_f_avg 711 8.78 Pump : P_min 0.3 barTein 400 grd CHI_peak 161.8 W/cm Max_T_f_surf 555 21.3 Pump_act 0.201 MW P_mult1 1DT 80.0 grd Pin/Fuel Properties Data: Max T clad 525 29.9 P_pump_100 0.201 MW N_Rey_trans 1187.4Taus 480.0 grd kclad 0.218 [W/cmK] 753.2 P_blower_100 0.201 MW N_Rey_up 5000

Chi_ist_dist 140.29 W/cm k_fuel 0.0419 [W/cm*K] T_cool_out 480.0 44.6 NUSSELT-Flag 0 Subbotin(tube)alph_turb 0.0791 BlasiusChi_ist_cos 140.30 W/cm hgap 3.8800 -13.8 Av_T_cool 439.9 -0.54 Dpgitter 0.09170 bar beta_turb 0.25 BlasiusCHI0 140.29 W/cm hs_av 0.8723 [W/cm 2̂K] Av_T_f_eff 609.7 Dpbeschl 0.49626 bar alph_lam 16

flow_fr 1.000 flow fraction Av_T_fuel_center 797.0 -20.3 Dpcore 0.15646 bar beta_lam 1 TurbulentPein 10 bar kfuel_fact 1.000 [factor] Av_T_f_avg 663.2 -18.47 Dptotal 0.74442 bar N_Rey_aver 67564 Forced conv.P_fr 1.000 power fractionhgap_fact 1.000 44.6 Av_T_f_surf 529.5 -12.0 Dpsystem 1.40919 bar f_weight 0.0049 67129Pump_fr 1.0000 pump fractionhs_fact 1.000 [factor] Av_T_clad_surf 499.1 -9.1 (rho*vel 2̂)/2 5076 pascal w_nat 1880.60 kg/s

w 11986.72 kg/sec temp_drops: DP_core 0.15646 0.040 w_nat_fr 0.157w 11986.72 kg/sec delT_fuel_av 268.5 C DP_core_100 0.156 bar (w - w_nat) 10106.12Mpunkt 1.08E+00 kg/sec/Pin delT_gap_av 16.1 C DP_system 1.40919 bar K_orf 2.521 1.418

kg/s per SA 181.6 Mpunkt_100 1.08E+00 kg/sec/Pin delT_clad_av 14.4 C DP_boyancy 3468 pascal K_inlet 5.50 core inlet friction coefficient

Vpunktcore 1.14E+06 cm 3̂/sec Clad_failure inf hrs @ 100 bardelT_cl_cool_av 59.4 C 3468 3468 K_outlet 1.64 core outlet friction coeff

Design Pb -cooled Reactor : EFIT EOC Inter Core Zone 2init_cos



EFIT-Pb: CZ3 Outer Zone


EOC

MgO-MOX fuel

Static Calculations

Fission Gas ModelX_He 0.783 frX_Kr 0.017 frX_Xe 0.200 frk_He 2.64E-03 W/mK

k_Kr 8.25E-05 W/mK



MWd/kg EOC avg


Rel_gas_fr 1.00 EOC peak-burnMA_fr MOX_fract

0.543 0.50

dL 3.70 m

Ax_mult 0.97844124 1.) push "init", reset flow_fr E11 to 1.0, push "init" again. Repeat procedure until convergence is achieved in flow rate w grav 9.81 m/s 2̂B 29.0019 cm Qcore 141.00 MWth Max_T_fuel 818 6.63 Mpunktcore 12072.47 kg/sec Zeta 1.893Cosine-Ax 1 CHI_peak 151.5 W/cm Max_T_f_avg 674 9.86 Pump : P_min 0.3 barTein 400 grd CHI_peak 150.6 W/cm Max_T_f_surf 536 24.9 Pump_act 0.202 MW P_mult1 1DT 80.0 grd Pin/Fuel Properties Data: Max T clad 513 34.6 P_pump_100 0.202 MW N_Rey_trans 1187.4Taus 480.0 grd kclad 0.218 [W/cmK] 753.1 P_blower_100 0.202 MW N_Rey_up 5000

Chi_ist_dist 129.52 W/cm k_fuel 0.0433 [W/cm*K] T_cool_out 480.0 44.6 NUSSELT-Flag 0 Subbotin(tube)alph_turb 0.0791 BlasiusChi_ist_cos 129.52 W/cm hgap 3.8234 -12.7 Av_T_cool 439.9 -0.54 Dpgitter 0.11234 bar beta_turb 0.25 BlasiusCHI0 129.52 W/cm hs_av 0.9427 [W/cm 2̂K] Av_T_f_eff 582.5 Dpbeschl 0.40671 bar alph_lam 16

flow_fr 1.000 flow fraction Av_T_fuel_center 749.5 -19.9 Dpcore 0.22537 bar beta_lam 1 TurbulentPein 10 bar kfuel_fact 1.000 [factor] Av_T_f_avg 630.2 -17.75 Dptotal 0.74441 bar N_Rey_aver 57120 Forced conv.P_fr 1.000 power fractionhgap_fact 1.000 44.6 Av_T_f_surf 510.8 -10.6 Dpsystem 1.40917 bar f_weight 0.0051 56753Pump_fr 1.0000 pump fraction hs_fact 1.000 [factor] Av_T_clad_surf 485.7 -7.7 (rho*vel 2̂)/2 5629 pascal w_nat 1894.08 kg/s

w 12072.47 kg/sec temp_drops: DP_core 0.22537 0.040 w_nat_fr 0.157w 12072.34 kg/sec delT_fuel_av 239.7 C DP_core_100 0.225 bar (w - w_nat) 10178.40Mpunkt 9.98E-01 kg/sec/Pin delT_gap_av 13.4 C DP_system 1.40917 bar K_orf 0.000 1.418

kg/s per SA 167.7 Mpunkt_100 9.98E-01 kg/sec/Pin delT_clad_av 11.8 C DP_boyancy 3468 pascal K_inlet 5.50 core inlet friction coefficient

Vpunktcore 1.15E+06 cm 3̂/sec Clad_failure inf hrs @ 100 bardelT_cl_cool_av 45.9 C 3468 3468 K_outlet 1.64 core outlet friction coeff

Design Pb -cooled Reactor : EFIT EOC Outer Core Zone 3init_cos


486

440480

513

750

630674

536

818

511

400

450

500

550

600

650

700

750

800

850

-45 -35 -25 -15 -5 5 15 25 35 45


Tem

per

atu

res

[°C

]

Clad surf

Coolant

Center Fuel

Surf Fuel

Avg Fuel



Grid spacer calculation for EFIT-Pb

Grid spacers pressure drop is calculated as follows:

,2

22 v

cNP vspacers

where: N – number of grid spacers, N = 6 ;

cv – modified loss coefficient of spacer, for CZ1/CZ2/CZ3 correspondingly equal to 7.33/7.38/7.56 ;

ε – flow section blockage factor by the spacer, for CZ1/CZ2/CZ3 correspondingly equal to 0.201/0.201/0.209 (for open dimple design).

Hexagonal box o outer width: wb = 13.63 mm o thickness: 0.3 mm o outer perimeter of the box: pb = ( 13.63 / (2 * cos 30) ) * 6 = 47.217mm o total section occupied of 168 box wall: Sb = 47.217 * 0.3 * 168 = 2380mm2 Dimples (open type) o outer radius of the dimples: rd = 2.205 mm o thickness th = 0.3 mm o numbet of dimples in one box : 3 o section occupied by the dimples in one box: Sd1 = π * 2.205 * 0.3 * 3 = 6.2312 mm2 o section occupied by the dimples in 168 box: Sd = 6.2312 * 168 = 1046.8 mm2 External hexagonal layer o outer width of the layer: wl = 178 mm o thickness of the layer: th = 0.3 mm o outer perimeter of the layer: p1 = ( 178 / (2 * cos 30) ) * 6 = 616.628 mm o section occupied by the layer: Sl = 616.628 * 0.3 = 185 mm2 • Total transversal area occupied by the spacer:

Av=Sb + Sd + Sl = 2380 + 1046.8 + 185 = 3611.8 mm2 • Relative plugging of the flow area by the spacer grid:

ε = Av / Ab = 3611.8 / 17527 = 0.206 • Pressure loss through the grids according to [16]: Number of grids: Ng = 6 Grid loss coefficient Cv = 6 ÷7; The value Cv = 7 is assumed Relative plugging: ε = 0.206 ΔPg = Ng * Cv * ε2 * ( mfr2 / (2 * ρ *Ab2) ) = 6 * 7 * 0.2062 * (1852 / (2 * 10516 * 0.0175272) ) = 9441 Pa



1. EFIT-Pb ULOF Transient Cases Analysed using SIM-ADS

Comparison to RELAP BOC calculations performed by ENEA and Ansaldo(ENEA: G. Bandini, P. Meloni, M. Polidori, ANSALDO: L. Mansini):

1a. ULOF: BOL, Avg Pin, Peak Pin

1b. ULOF: EOC, Avg Pin, Peak Pin


IRS /FzK W.M.Schikorr EUROTRANS WP1.5 Safety Meeting : Bologna, May 28-29, 2008

15

The EFIT Reactor Design:

4

EFIT is a pool-type reactor of about 400 MW power

Sub-critical reactor (Keff = 0.97) sustained by a spallation neutron source (beam proton energy 800 MeV and beam current 20 mA)

Reactor core with 3 U-free fuel zone with (Pu,MA)O2 in MgO matrix to improve the burning efficiency

Pure melt lead as primary coolant (lower cost and less activation products such as Polonium than LBE)

Core power is removed by forced circulation (4 pumps placed in the hot collector) through 8 steam generators with helical-coil tube bundle

4 DHR heat exchangers are immersed in the annular cold pool between the inner vessel and the reactor vessel

DHR

Steam generator

DHR

Steam generator

Pump

Core

Target

Reactor vessel

Inner vessel

heat exchanger

EFIT Reactor Block

Proton Beam

Figure Source: G. Bandini, P. Meloni, M. Polidori (ENEA - Bologna)



SIMMER-III ANSALDOResults at after 1 hourt = 3600 s: (P = 16 MW)

mC = 2740 kg/s

mD = 2983 kg/s 2985 Kg/s

TCi = 410.5 C

TCo = 449.1 C

TDi = 444.6 C 444 C

TDo = 407.0 C 407 C

y = mC(TDi - TDo)

(TCi - TDo)

x = y + mD - mC

y = 255 kg/s

Recirculation ratio at DHR outlet:x = 498 kg/s (17% of mD)

Simplified scheme of RELAP5 model

xy

mC

mD

TCi

TCo

TDo

TDi

TDi

TCi

TCo

TCi

TCo


mC = 2740 kg/s

mD = 2983 kg/s 2985 Kg/s

TCi = 410.5 C

TCo = 449.1 C

TDi = 444.6 C 444 C

TDo = 407.0 C 407 C

y = mC(TDi - TDo)

(TCi - TDo)

x = y + mD - mC

y = 255 kg/s



xy

mC

mD

TCi

TCo

TDo

TDi

TDi

TCi

TCo

TCi

TCo

xy

mC

mD

TCi

TCo

TDo

TDi

TDi

TCi

TCo

TCi

TCo


The In-vessel Flow Paths during normal Heat Removal mode:



EFIT-Pb : ULOF, BOC, RELAP results May 2008 Source:(G. Bandini)3 DHRS in operation, Power level remains at ~100% during transient

Core Flow Rate

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 50 100 150 200

Time [°C]

rel.

Flo

w R

ate

Flow RELAP

FLOW SIM-ADS

Flow_i SIM-ADS

Flow RELAP

FLOW SIM-ADS

Flow_i SIM-ADS

Avg Core Temperatures

300

400

500

600

700

800

900

0 50 100 150 200

Time [sec]

Te

mp

era

ture

[°C

]

Tcore_in RELAP

Tcore_out RELAP

Tcore_in SIM-ADS

Tcore_out SIM-ADS

T_clad_RELAP

T_clad SIM-ADS

T_upper RELAP

T_upper SIM-ADS

Peak Core Temperatures

300

400

500

600

700

800

900

0 50 100 150 200

Time [sec]

Tem

per

atu

re [

°C]

Tcore_in RELAP

Tcore_out_peak RELAP

Tcore_in SIM-ADS

Tcore_out SIM-ADS

T_clad_peak RELAP

T_clad SIM-ADS

T_upper RELAP

T_upper SIM-ADS

Slide 1

What has changed since Madrid meeting:

w_nat has decreased to ~ 30% from ~ 38% during ULOF(ss) due to revised prim. system pressure drops



EFIT-Pb : ULOF, BOC, RELAP results May 2008 Source:(G. Bandini)3 DHRS in operation, Power level remains at ~100% during transient

Transferred MHX Power

0

50

100

150

200

250

300

350

400

450

0 50 100 150 200Time [sec]H

X P

ow

er t

ran

sfer

red

[M

W]

PHX RELAP

PHX tube SIM-ADS

PHX shell SIM-ADS

PHX water SIM-ADS

Slide 2

HX Temperatures

300

350

400

450

500

550

600

650

0 50 100 150 200Time [sec]

Tem

per

atu

re [

°C]

T_HX_out RELAP

T_HX_in RELAP

T_HX_out SIM-ADS

T_HX_in SIM-ADS



EFIT-Pb : ULOF, BOC, SIM-ADS results compared to RELAP May 2008 3 DHRS in operation, Power level remains at ~100% during transient

Core Flow Rate

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 50 100 150 200Time [°C]

rel.

Flo

w R

ate Flow RELAP

FLOW SIM-ADS


300

400

500

600

700

800

900

0 50 100 150 200Time [sec]

Tem

pe

ratu

re [

°C]

Tcore_in RELAP

Tcore_out RELAP

Tcore_in SIM-ADS

Tcore_out SIM-ADS

T_clad_RELAP

T_clad SIM-ADS

T_upper RELAP

T_upper SIM-ADS


300

400

500

600

700

800

900

0 50 100 150 200Time [sec]

Te

mp

era

ture

[°C

]

Tcore_in RELAP


Tcore_in SIM-ADS

Tcore_out SIM-ADS

T_clad_peak RELAP

T_clad SIM-ADS

T_upper RELAP

T_upper SIM-ADS

Slide 1



EFIT-Pb : ULOF, BOC, SIM-ADS results compared to RELAP 3 DHRS in operation, Power level remains at ~100% during transient

HX Temperatures

300

350

400

450

500

550

600

650

0 50 100 150 200Time [sec]

Te

mp

era

ture

[°C

]

T_HX_out RELAP

T_HX_in RELAP

T_HX_out SIM-ADS

T_HX_in SIM-ADS

Transferred MHX Power

0

50

100

150

200

250

300

350

400

450

0 50 100 150 200Time [sec]

HX

Po

wer

tra

nsf

erre

d [

MW

]

PHX RELAP

PHX tube SIM-ADS

PHX shell SIM-ADS

Slide 2



EFIT-Pb : ULOF, BOC, SIM-ADS results 3 DHRS in operation, Power level remains at ~100% during transient

Slide 3ULOF FzK (SIM-ADS) : Power and Flow Rate

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

0 50 100 150 200

Time [sec]

rel.

Un

its

[fr]

Power_th

Flow_CoolPower

Flow

ULOF FzK (SIM-ADS) : Clad Failure and Fission Gas Pressure

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

1E+10

1E+11

1E+12

1E+13

1E+14

1E+15

0 20 40 60 80 100 120 140 160 180 200Time [sec]

Cla

d F

ailu

re T

ime

[sec

]3.0

3.0

3.1

3.1

3.2

3.2

3.3

3.3

3.4

3.4

3.5

Fis

sio

n G

as P

ress

ure

[b

ar]

Clad Failure Time [sec]

Fission Gas Pressure [bar]

30 min

Min. Pin Clad Failure Time = 3 hrsMin. Pin Clad Failure Time at ULOF(ss) ~

1E8 sec

1. Acceptable agreement between SIM-ADS and RELAP by assuming P_core ~ 100% during ULOF transient, and by making appropriate assumptions as regards inertial masses in the various primary system flow path volumes are made

2. Max clad temperatures of peak pin ~ 850 °C 18 seconds into ULOF due to flow undershoot down to ~ 10%,

3. For BOC conditions, minimum pin clad failure time > 30 minutes (acceptable !)

4. Need reactivity coefficients for EFIT-Pb to assess more realistic power response during ULOF transient

Conclusions:



EFIT-Pb Reactivity Coefficient Data:

Source : G.Glinatsis, „EFIT-MgO/Pb Core Design Reactivity Coefficients” Genova, April Meeting 2008

Coolant density Effect: 1% dens

whole Active Core zones: (DK/K )/ 1% dens = 0.00058 0.00002

Fuel Temperature Effect: T nom_fuel/zone 1800 K,

BoL: Keff = 0.96147 0.00025; ( 0.96123 0.00027)

BoC: Keff = 0.96207 0.00025; (0.96183 0.00025 )

EoC: Keff = 0.96227 0.00026; (0.96227 0.00026 ).

This translates to:

Coolant temp. coeff ~ + 0.65 pcm/°C

Fuel temp. coeff ~ - 0.014 pcm/°C,

or A_dopp ~ - 20 pcm

Please somebody else verify above data calculations in term of [pcm/°C] !



EFIT-Pb : ULOF, EOC, SIM-ADS calcs. compared to RELAP May 2008 (BOC),

3 DHRS in operation, realistic reactivity coefficients, power level >100%

Slide 1

Core Flow Rate

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 50 100 150 200Time [°C]

rel.

Flo

w R

ate

Flow RELAP

FLOW SIM-ADS


300

400

500

600

700

800

900

0 50 100 150 200Time [sec]

Te

mp

era

ture

[°C

]

Tcore_in RELAP


Tcore_in SIM-ADS

Tcore_out SIM-ADS

T_clad_peak RELAP

T_clad SIM-ADS

T_upper RELAP

T_upper SIM-ADS


300

400

500

600

700

800

900

0 50 100 150 200Time [sec]

Te

mp

era

ture

[°C

]

Tcore_in RELAP

Tcore_out RELAP

Tcore_in SIM-ADS

Tcore_out SIM-ADS

T_clad_RELAP

T_clad SIM-ADS

T_upper RELAP

T_upper SIM-ADS



EFIT-Pb : ULOF, EOC, SIM-ADS calcs. compared to RELAP 3 DHRS in operation, realistic reactivity coefficients, power level >100%

Slide 2

ULOF Conclusions:

1. Power level > 100% during above ULOF transient due to ~ 0 Doppler coefficient and positive coolant coef.

2. Peak Fuel temperatures always remain < 1500 °C (not explicitly shown in above transparencies, thus no concern as regards possible MgO-MOX fuel evaporation expected )

3. Max clad temperatures of peak pin ~ 870 °C 18 seconds into transient,

ULOF FzK (SIM-ADS) : Power and Flow Rate

0.00.10.20.30.40.50.60.70.80.91.01.1

0 50 100 150 200Time [sec]

rel.

Un

its

[fr]

Power_th

Flow_CoolPower

Flow

ULOF FzK (SIM-ADS) : Temperatures

300

500

700

900

1100

1300

1500

0 50 100 150 200Time [sec]

Tem

per

atu

re

[°C

]

Fuel_c_peakClad_peakCool_outCool_in

Fuel

T_clad_max = 880 °C

Coolant

Cladding



EFIT-Pb : ULOF, EOC, SIM-ADS calcs. compared to RELAP 3 DHRS in operation, realistic reactivity coefficients, power level >100%

Slide 3

ULOF Conclusions cont:

4. For EOC conditions, minimum pin clad failure time ~ 80 sec because of flow undershoot down ~ 10% flow (acceptable ?????). Could expect peak pin clad leakages during this transient. Note: assumed 100% fission gas release in above calculations (very conservative !!, more realistic is probably ~ 70-80%)

ULOF FzK (SIM-ADS) : Power and Flow Rate

0.00.10.20.30.40.50.60.70.80.91.01.1

0 50 100 150 200Time [sec]

rel.

Un

its

[fr]

Power_th

Flow_CoolPower

Flow

ULOF FzK (SIM-ADS) : Clad Failure and Fission Gas Pressure

1E+00

1E+01

1E+02

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

1E+09

1E+10

1E+11

0 50 100 150 200Time [sec]

Cla

d F

ailu

re T

ime

[sec

]

88

90

92

94

96

98

100

102

104

Fis

sio

n G

as P

ress

ure

[b

ar]

Clad Failure Time [sec]

Fission Gas Pressure [bar]

30 min

Min. Pin Clad Failure Time = 80sec Min. Pin Clad Failure Time at ULOF(ss) =

1E5 sec



2. EFIT-Pb PLOH Transient using SIM-ADS

Comparison to RELAP BOC calculations performed by ENEA and Ansaldo(ENEA: G. Bandini, P. Meloni, M. Polidori, ANSALDO: L. Mansini):

DHRS operational mode (such as PLOHS): BOL

Sequence of events:

1. Total Loss of primary heat sink (loss of all MHX)

2. Source shutdown; decay heat as heat source

3. 3 out of 4 DHRS systems function as heat sink



27

The Decay Heat Removal (DHR) System of EFIT-Pb

The DHR system is conceived for inherently safe decay heat removal and passive mode actuation

4 independent loops partially filled with organic oil, that dissipate the decay heat to the atmosphere by natural convection circulation

Each loop consists of a dip cooler immersed in the cold pool where the oil partially vaporize and an air-vapor condenser with stack chimney and interconnecting piping

Oil boiling point is determined by superimposed pressure of an inert gas

In normal operation the oil is below its boiling point and the DHR removes only heat losses from SGs and inner vessel (few 100 kW) to keep cold the upper part of the reactor vessel

Condensed Oil

Boiling Oil

Cooling air Chimney

Air Vapour Condenser

Nitrogen Header

Oil VapourSeparator

Condensed Oil Drum

EFIT ReactorSafety-Related DHR Loop

DHRDip Cooler

Inner vessel

Reactor vessel





mC = 2740 kg/s

mD = 2983 kg/s 2985 Kg/s

TCi = 410.5 C

TCo = 449.1 C

TDi = 444.6 C 444 C

TDo = 407.0 C 407 C

y = mC(TDi - TDo)

(TCi - TDo)

x = y + mD - mC

y = 255 kg/s



xy

mC

mD

TCi

TCo

TDo

TDi

TDi

TCi

TCo

TCi

TCo


mC = 2740 kg/s

mD = 2983 kg/s 2985 Kg/s

TCi = 410.5 C

TCo = 449.1 C

TDi = 444.6 C 444 C

TDo = 407.0 C 407 C

y = mC(TDi - TDo)

(TCi - TDo)

x = y + mD - mC

y = 255 kg/s



xy

mC

mD

TCi

TCo

TDo

TDi

TDi

TCi

TCo

TCi

TCo

xy

mC

mD

TCi

TCo

TDo

TDi

TDi

TCi

TCo

TCi

TCo


The In-vessel Flow Paths during the Decay Heat Removal mode:



DHRS Mode Issues:

1. How long does it take until the complicated natural convection flow pattern in EFIT-Pb is established ?

2. ENEA / ANSALDO have performed SIMMER III and RELAP calculations trying to obtain a first estimate of the time it will take until heat removal via natural circulation through the DHRS dip coolers is established.

See presentation by G. Bandini, P. Meloni, M. Polidori, „Assessment of Decay Heat Removal by Natural Circulation in the EFIT Reactor” during THIRS meeting in Karlsruhe April 14-16 2008.

3. RELAP needed some modifications in pressure drop coefficients to simulate the time delay effect. SIM-ADS needs similar adjustments.



30

0

1000

2000

3000

4000

5000

0 1000 2000 3000 4000 5000Time (s)

Flo

w r

ate

(kg

/s)

Core flow (simmer)

DHR flow (simmer)

Core flow (relap5)

DHR flow (relap5)

0

5

10

15

20

25

30

0 1000 2000 3000 4000 5000

Time (s)

Po

we

r (M

W)

DHR power (simmer)

DHR power (relap5)

Decay power

Core and DHR Mass Flow RateCore Decay and DHR Power

Core Decay Heat Removal in Natural Circulation

RELAP and SIMMER III Code Result Comparison to PLOHS

Both codes (SIMMER and RELAP) predict efficient removal of decay power after about 2000 s

Mass flow rates through the core and DHR well compare in the medium term

Code results differ in the initial transient owing to the different modelingFigure Source: G. Bandini, P. Meloni, M. Polidori (ENEA - Bologna)



31

0

1000

2000

3000

4000

5000

0 1000 2000 3000 4000 5000Time (s)

Flo

w r

ate

(kg

/s)

Core flow (simmer)

DHR flow (simmer)

Core flow (relap5)

DHR flow (relap5)

0

5

10

15

20

25

30

0 1000 2000 3000 4000 5000

Time (s)

Po

we

r (M

W)

DHR power (simmer)

DHR power (relap5)

Decay power

Core Decay Heat Removal in Natural CirculationSIM-ADS, RELAP and SIMMER III Code Result Comparison to PLOHS

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0 1000 2000 3000 4000 5000Time [sec]

Flo

w R

ate

fr

Core Flow SIMMER

Core Flow RELAP

DHRS Flow Rate SIMMER

DHRS Flow Rate RELAP

SIM-ADS

0

5

10

15

20

25

30

0 1000 2000 3000 4000 5000Time [sec]

Pow

er [M

W]

Decay Heat

DHRS RELAP

DHRS SIMMER

Decay Heat SIM-ADS

DHRS SIM-ADS

1. w_nat ~ 9% during DHRS mode

2. ~ 2000 sec full nat. convection flow established

1. SIM-ADS predicts overshoot in heat removal of DHRS HX compared to RELAP and SIMMER

2. ~ 4000 sec removal of heat in balance with decay heat

3. What limits heat removal in DHRS HX to ~ 20 MW ???



Conclusion:To continue and fianlize our EFIT-PB transient anlysis:

1. We need to decide if the thermal inertia of the nominal heat flow path as encountered during ULOF transient (i.e natural convection response after primary pump shutdown) with a flow undershoot down to ~ 10% nominal flow (or even less) shall be accepted as reference and then be used during all the transients with similiar primary system plant response.

2. We need to decide if the thermal inertia of the DHRS heat flow paths as encountered during a PLOH or ULOH as predicted by SIMMER III (and adjusted to in RELAP and in SIM-ADS) shall be accepted as the reference response of the primary system (i.e., it takes about 2000 sec until full DHRS nat. convection flow is establihed).

3. The response of the DHRS and MHX heat exchanger to various transients needs to be checked by the various codes as SIM-ADS predicts an overshoot in the DHRS HX heat removal during the PLOHS transient.

4. Definition of the secondary side conditions of the DHRS HX : T_inlet = 392 °C ??T_inlet = 404 °C ??, T_sat = ???, what are pressure conditions P= 11.5 bar ???, consistency with oil property tables ??, what tables ??



33

18

Core and DHR Mass Flow Rate Core Decay and DHR Power

PHLOS Transient: RELAP5 Results (1)

Reactor trip is calculated by RELAP5 at 46 s

After some initial oscillations (free level movements) core and DHR mass flow rates becomes stable and the DHR attains maximum performance (20 MW for 3 loops in operation) after about 700 s

0

5

10

15

20

25

30

0 2000 4000 6000 8000 10000Time (s)

Po

we

r (M

W)

DHR power (relap5)

Decay power

0

5000

10000

15000

20000

25000

30000

35000

0 100 200 300 400 500

Time (s)

Flo

w r

ate

(kg

/s)

Core flow (relap5)

DHR flow (relap5)

Reactor trip

THIRS Workshop, Forschungszentrum Karlsruhe, Germany, April 14-16, 2008

Forschungszentrum Karlsruhe Technik und Umwelt IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting :...

Documents

Transcript of Forschungszentrum Karlsruhe Technik und Umwelt IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting :...