Status of He-EFIT Design Pierre Richard – J. F Pignatel – G. Rimpault

WP1.5 Meeting, Lyon, October 10-11 , 2006, P. Richard, J. F. Pignatel, G. Rimpault 1

Status of He-EFIT Design

Pierre Richard – J. F Pignatel – G. RimpaultRichard – J. F Pignatel – G. Rimpault


Outline

Recall of the Design Approach

Main Issues Addressed since the February (Bologna) Meeting

Updated Table of He-EFIT Main Characteristics

Presentation of the current core design : Core, Spallation module, Power Conversion Cycle

DHR Approach

Conclusions – Next steps


1 – Spallation module design using the outcome of the PDS-XADS Project

2 - Define the Proton Beam Intensity (for a maximum proton energy of 800 MeV), the reactor power and the Keff (assuming the potential reactivity insertions and burn up swing which have to be checked later)

3 - Design the core taking into account the design objectives (MA burning, Keff considerations,…) and the core design constraints (Fuel composition, cladding composition, pressure drops,…)----------------------------------------------------------------------------------4 - Define the approach for the DHR and design the DHR main components (blowers, HX,…)

5 - Design the primary system

6 - Design the Balance of Plant and Containment and implementation of the plant (cooling loops, confinment building, …)

Steps 2 and 3 require iteration loops with neutronics, T/H and geometry considerations Required some time

He-EFIT Design Approach


Evolutions since the Bologna Meeting (1/3)

Proton beam characteristics : Energy changed from 600 MeV to 800 MeV which is currently considered as an upper limit : over 800 MeV, the radio-toxicity increase rapidly Need for higher proton beam intensity 18-22 mA instead of 10-20 mA

Plant Efficiency : First Assessment made at CEA : with Tin/Tout = 400/550 °C AMEC/NNC : incentive to increase the Tcore from 150 °C to 200 °C Decision from the Lyon meeting (03/06) : Tin/Tout = 350/550 °C

Plant efficiency increased to 43.3 % Fuel Characteristics :

CERCER (MgO matrix) limit temperature at nominal conditions decreased from 1860 °C to 1380 °C CERMET (Mo matrix) considered as back up solution (decision from the Cadarache meeting in June)

S/A Characteristics : S/A Outer width over flats reduced from 162 mm to 137 mm : target size corresponding to 19 S/A at the center of the core



Core Design : Core power decreased to 400 MWth (600 MWth before) 3 zones core with different pin diameters

Peaking factors : Total peaking factor changed from 1.61 to 1.839 : iteration with neutronic calculations

Adaptation to He-EFIT of the objectives defined by the “Specialist Meetings” (March-June 2006) :

42 Kg MA burnt par TWhth Flat Keff versus BU Reasonably low current requirement < 20 mA Low pressure drop < 1.0 bar Clad temperature limit < 1600°C (transient),

< 1200°C (nominal) Coolant speed < 50 m/s

Others : Wrapper Thickness, Number of grids, …



Cross-check with FzK and modifications of the correlations for Heat Exchange Coefficients, Core Pressure Drops and Fuel Conductivities (According to DM3 recommendations) : Rather good agreement :

Core composition f < 0.05 % Fuel Max Temperatures T< 20 °C Cladding Max Temperatures T< 6 °C Pressure drops : incoherency in the Dh calculations

but small consequences : (P) < 0.034 bar

Safety :

Pressure drop limited to 1 bar for the core and 1.5 bar for the whole primary circuit

Provisional value to be checked by appropriate transient calculations

DHR strategy - Comparison of different two approaches : “XADS-like” approach / GCFR approach


Design Parameter Value/Characteristic Comments PLANT GENERAL CHARACTERISTICS

Coolant Helium at 70 bars Identical to GCFR value Core Power 400 MWth After iterations with neutronic

calculations Core Power Density 50 MW/m3 60 MW/m3 proposed in June

2005 Plant Efficiency 43.3 % without acc. Requirement : 40 %

Core Inlet/outlet Temp 350°C/550°C Delta T increase by 50 °C Power conversion Indirect cycle S-CO2 with re-

compression

Accelerator LINAC E : 800 Mev I : 18-22 mA

Over 800 MeV, Spallation Products have longer half-life Upper limit fixed to 800 MeV

Target Unit interface Window Target Solid Target

W rods cooled by helium – separate cooling of the window

Loading Factor 75 % Provisional value to be checked later

Main Characteristics of the Gas-Cooled EFIT (1/3)


CORE GENERAL CHARACTERISTICS Fuel Composition (Pu, Am, Cm)O2 + MgO 50/50 % Fuel/Matrix ratio Fuel (pellet) Power density

App. 200 W/cm³ To be adjusted after transmutation optimisation

Fuel content Ratio 30 % (Pu/MA+Pu) To be adjusted after transmutation optimisation

Fuel and MA Vectors Provided by GR Fuel Pin Spacer Grid 5 grid spacers Fuel Assembly type Wrapper 4 mm thickness Fuel Assembly cross section

Hexagonal

Core zoning 3 Zones Different pin diameters S/A pitch 137 mm Adjusted for an optimum target size Peaking Factor 1.839 Same peaking factors considered in

the three zones Core height 1.25 m Core Pressure Drop Range 0.7-1 bar Based on GCFR assessment. To be

checked at a second stage by transient calculations



PIN CHARACTERISTICS Cladding material SiC Cladding thickness 1 mm Minimum Thickness for Feasibility reasons (to be

checked by CEA) Fuel/Cladding Gap 100 µm for 5.8 mm in

Diameter – Changed proportionally to the pellet diameter

Provided by DM3

DESIGN CRITERIA Tfuelmax 1380 °C DBC cat. I Tfuelmax 1580 °C DBC cat. II Tfuelmax 1780 °C DBC cat. III Tcladmax 1200 °C DBC cat. I Tcladmax 1300 °C Long-term transient(>24h) Tcladmax 1600 °C Short-term transient(<24h)

SAFETY ISSUES Protected transients The plant shall be designed

to accommodate PLOF/PLOCA

The analysis of protected transients similarly to the XADS is to be done (transient list to be checked with WP1.5)

DHR Approach No Back-up pressure (no guard containment) Core-catcher

DHR Under nominal pressure : Nat. circulation Depressurised cond. : active DHR systems to remove Decay Heat

Decay Heat Curve deduced from the banchmark



Current Design

A three zone core has been preliminarily studied : Zone 1 (inner) : 45 MWth, 42 sub-assemblies Zone 2 (intermediate) : 165 MWth, 156 sub-assemblies Zone 3 (outer) : 191 MWth, 180 sub-assemblies

The main hypothesis and/or design objectives accounted are the following :

Core heigth : 125 cm External width over flat : 137 mm Fuel (fuel+matrix) fraction in the diffrent zones : 11%, 21.5 % and 35 % (for respectively zone 1, 2 and 3) Matrix volmue fraction in the fuel pellet : 50 %- The total form factor was assumed to be the same in the three zones (1.839)

Remarks : 1 - Core pressure drops are not equilibrated (too many design constraints). They are respectively 0.84, 0.74 and 1 bar in zone 1, 2 and 3 some gagging will be necessary2- The pellet diameter in zone 1 is rather small (2.3 mm). If this induces some problem, the number of pin rows per S/A can be reduced to 11 row per S/A.


Current Design – 50 MW/m3 (1/2)

EFIT TypeThermal Power (MWth)Coolant TypeCoolant Pressure (bar)Inlet Temperature (°C)Outlet Temperature (°C)Cladding TypeSpallation moduleZone 1 (inner) 2 (intermediate) 3 (outer)Matrix Type MgO MgO MgOMatrix Fraction 50% 50% 50%Volume of the fissile zone (m 3̂) 0,915 m3 / 0.917 3,39 m3 / 3.40 3,93 m3 / 3.93Core GeometryOuter Diameter of the fissile zone 1,16 m / 1.165 2,19 m / 2.197 2,97 m / 2.97Height of Sub-Assemblies 2.75 m 2.75 m 2.75 mNumber of fissile sub-assemblies 42 156 180Fissile Height (H) 1,25 m 1,25 m 1,25 mWrapper Width over outer Flats 137 mm 137 mm 137 mmWrapper Thickness 4,0 mm 4,0 mm 4,0 mmInter-Wrapper Gap 5,0 mm 5,0 mm 5,0 mmCoolant Volume Fraction (%) 49.8% / 48.03 44.75% / 42.62 37.19% / 34.08Fuel Volume Fraction (%) 5.58% / 6.00 10.85% / 10.81 17.49% / 17.51Matrix Volume Fraction (%) 5.58% / 6.00 10.85% / 10.81 17.49% / 17.51Structure Volume Fraction (%) 39.05% / 40.02 33.56% / 34.23 27.83% / 28.44

He-EFIT400He 71350550SiC

Solid W He cooled


Sub-Assembly Bundle GeometryNumber of Pin per S/A 469 217 91Number of Pin rows per SA 12 8 5Pin outer Diameter 4,38 mm 6,87 mm 11,57 mmCladding Roughness Smooth Smooth SmoothPitch to Rod Ratio 1,35 1,25 1,14Pitch (mm) 5,89 mm 8,60 mm 13,20 mmHydraulic Diameter 4.36 / 4.16 5 / 4.86 5.05 / 5.05Cladding Thickness 1,00 mm 1,00 mm 1,00 mmPellet/Cladding Gap 0,040 mm 0,081 mm 0,160 mmPellet Diameter 2,30 mm 4,71 mm 9,25 mmCore Thermal-HydraulicsAverage Coolant Speed in the Fissile Core m/s 30 / 29.8 34.5 / 34.4 45 / 45.3Average Reynolds Number in the Core 16958 / 16147 22621 / 21771 29643 / 29749Average Prandtl Number in the Core 0.64 / 0.672 0.64 / 0.67 0.64 / 0.67Average Nusselt Number in the Core 44 / 46.4 54 / 57.2 65 / 70.8Average Pin Linear Power W/m 18 / 18 39 / 39 93 / 93Form Factor 1.839 / 1.839 1.839 / 1.839 1.839 / 1.839Max Pin Linear Power W/m 33 / 33 72 / 72 171 / 171Hottest Channel ThermicsMax Cladding Temperature in the Hottest Channel °C 686 / 682 700 / 694 711 / 704Max Fuel Temperature in the Hottest Channel °C 792 / 772 950 / 927 1310 / 1322Core Pressure Drop (bar)Grid Number 5 5 5Total Core Pressure Drop bar 0.84 / 0.874 0.74 / 0.734 1.01 / 0.978Total Regular Pressure Drop bar 0.47 / 0.49 0.52 / 0.525 0.81 / 0.816Total Singular Pressure Drop bar 0.37 / 0.383 0.22 / 0.21 0.2 / 0.16Power MW 45 / 44 165 / 165 191 / 190

Note 1 : the number after the slash ( / ) are SIM-ADS results 15. Sept.06

Current Design – 50 MW/m3 (2/2)


750

180

267

307

Di 370 Ep. 10

840

9755

170

200

200

200

200

252

3

“Cold” Window Concept (1/2)


He flow

Target lower peripheral ring also in W (assume a porosity of 50% for He flow))

Target central part made of a bundle of horizontal W-rods (see detail A)

Dext = 266 mm

“Cold” Window Concept (2/2)

Axial pitch

Proton Beam

Radial pitch

Helium


Power Conversion Cycle – AMEC-NNC Assessment

Assumptions :

Keeping the indirect Supercritical CO2 cycle with re-compression

CO2 remains super-critical : CO2 characteristics above the Critical Point (74 bar/32 °C). This avoids the presence of water in the compressors (badly known behaviour of the components)

CEA Low Heat sink Temperature considered too restrictive : 16 °C 21 °C

Parametric study on the core inlet temperature : +/- 50 °C


Power Conversion Cycle

He

CO2s

71 bar 400 °C

70 bar 550 °C

69.6 bar 394 °C

250 bar 520 °C

59.9 bar 355 °C

59.5 bar 214 °C

59.1 bar 63 °C

58.7 bar 21 °C

251.8 bar 46 °C

251.4 bar 196 °C

251 bar 315 °C

251.4 bar 201 °C

water 16 °C

Turbine

Auxiliary Compressor

Main Compressor

43.3 %


Decay Heat Removal - Approach

Goal :

Compare different strategies :

• Active/Passive

• Guard Containement/No guard Containment

Background :

GCFR Approach

PDS-XADS (He-cooled XADS)


Schematic of DHR system (CEA initial proposal)

Exchanger #2

pool

Exchanger #1

core

Secondary loop

dedicated DHR loops

H1

H2

Guardcontainment

-3 loops of DHR

-3 pools

-1 guard containment


DHR (CEA studies)

Preliminary design of a Decay Heat Removal system from theGFR 600 MWth : primary loop

75,00% 125,00% 175,00% 225,00%

Ba

ck

up

pre

ss

ure

(B

ar)

Fully

25 bar

7 bar

1 bar

5 kWe

265 kWeForced convection required during a very long time

,


75,00% 125,00% 175,00%

Ba

ck

up

pre

ss

ure

(B

ar)

Fully natural conv. (15 m)

25 bar(34 bar)

7 bar

1 barForced convection required during a very long time

,Fuel plates core 100 MW/m3, simplified steady approach

3%PN (~ 5 mn) 0,6%PN (1 day)

Tfuel < 1600°C Tfuel < 1300°C

TinCore = 330°C (480°C) TinCore = 110°C

Residual power (ANS+10% : %PN)

STATUS ON THE DHR SYSTEM CAPABILITY

Fully natural convection, considering Hdriving = 15 m

7 bar5 kWe

3 bar~ 50 kWe Forced convection required during a long time (>1 month)

(for Pn of 40 bar/TinCore 480°C/TfuelMax 1300°C, Hdriving required : ~15 m)

~ 10 kWe

~ 500 kWe


75,00% 125,00% 175,00% 225,00%

Ba

ck

up

pre

ss

ure

(B

ar)

Fully

25 bar

7 bar

1 bar

5 kWe

265 kWeForced convection required during a very long time

,


75,00% 125,00% 175,00%

Ba

ck

up

pre

ss

ure

(B

ar)

Fully natural conv. (15 m)

25 bar(34 bar)

7 bar

1 barForced convection required during a very long time

,Fuel plates core 100 MW/m3, simplified steady approach

3%PN (~ 5 mn) 0,6%PN (1 day)

Tfuel < 1600°C Tfuel < 1300°C

TinCore = 330°C (480°C) TinCore = 110°C

Residual power (ANS+10% : %PN)

STATUS ON THE DHR SYSTEM CAPABILITY

Fully natural convection, considering Hdriving = 15 m

7 bar5 kWe

3 bar~ 50 kWe Forced convection required during a long time (>1 month)

(for Pn of 40 bar/TinCore 480°C/TfuelMax 1300°C, Hdriving required : ~15 m)

~ 10 kWe

~ 500 kWe


GFR STRATEGY (CEA Approach)

•For the GFR 2400MWth

-The high back-up pressure strategy (25Bar) is not kept

-for GFR the intermediate back-up pressure strategy (~5 Bar) is studied

-Back Up solution :The full depressurisation (1Bar) (still not studied)


PDS-XADS

Basic Reactor options:

• Reactor power : 80MWth• First core: classical FBR fuel U-PuO2 (35% Pu max)• Accelerator: designed for 600MeV/6mA but can be upgraded to 800MeV/10mA• Core and Target Unit designed for 600MeV/6mA• Separated target: liquid • Primary circuit: He

No Guard Containment

Full depressurization 1 Bar

Integrated SCS (but only 2 MWth to be removed by each SCS)

DHR Strategy :


Integrated SCS

(Electric Power 55kW)

PDS-XADS SCS Design


DHR for EFIT

For He-EFIT:

The PDS-XADS solution seems better

Proton beam complexity Guard containment not keep

If the full depressurization is chosen, a strategy must bedefined :

The blowers must work 1 to 70 Bars : Requires High Power and a complex Blower Design (or 2 systems : 1-10 bars and 10/70 bars? )

OR

Blowers can work only at low pressure :

Acton for fast depressurization System systematically used (safety)

SIMPLIFICATION of procedures

System implementation :

3 DHR loops designed for 100 %

2 Solutions : Loops integrated on the vessel/Ex-vessel loops


Conclusions (1/2)

Current Design : A three zone core has been preliminarily studied :

Zone 1 (inner) : 45 MWth, 42 sub-assemblies Zone 2 (intermediate) : 165 MWth, 156 sub-assemblies Zone 3 (outer) : 191 MWth, 180 sub-assemblies

The main hypothesis and/or design objectives accounted are the following :

Core height : 125 cm External width over flat : 137 mm Fuel (fuel+matrix) fraction in the different zones : 11%, 21.5 % and 35 % (for respectively zone 1, 2 and 3) Matrix volume fraction in the fuel pellet : 50 %- The total form factor was assumed to be the same in the three zones (1.839)

DHR Approach under discussion


Conclusions (2/2)

Next steps :

Detailed neutronic calculations : Neutron source behaviour by the mean of MCNPX CalculationsCore neutronics by the means of MCNPX and ERANOS calculations.

Even if the current core design is not fully defined, He-EFIT main characteristics (core power, main core dimensions) are sufficiently defined to go ahead with :

Safety Approach/DHR strategy :

Pre-sizing of the DHR loop components (AREVA ??) CATHARE/SIM-ADS modelling (CEA/FzK ???)

Remontage (AREVA)

Dissemination of the main He-EFIT design characteristics – Iteration with the partners

Documents

Status of He-EFIT Design Pierre Richard – J. F Pignatel – G. Rimpault