IP EUROTRANS WP 1.5 Safety Meeting KTH - Stockholm, May 22 nd – 23 rd 2007 Neutronic Design of the...

IP EUROTRANS

WP 1.5 Safety Meeting

KTH - Stockholm, May 22nd – 23rd 2007

Neutronic Design of the three zone

EFIT-MgO/Pb core(Task 1.2.4: ANSALDO, ENEA, FZK, CEA, CRS4, Framatome ANP, NNC)

C. Artioli, V. Peluso, C. Petrovich, M. Sarotto

ENEA, Italian Agency for new Technologies, Energy and Environment, FPN-FISNUCAdvanced Physics Technology Division, Via Martiri di Monte Sole, 4, 40100, Bologna, Italy

http://www.enea.it/prima.html

KTH Stockholm, 22nd – 23rd May 2007 , IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto

Summary

The 395 MWth EFIT/MgO-Pb two zone model

(Lyon Oct. 2006, WP1.5 meeting)

shows high ffrad in the outer zone

3 zones to respect the limit

on the clad T (avoiding

orificing in the same fuel zone)

Neutronic design performed by means of:

1) ERANOS ver. 2.0 deterministic code

- ERALIB1(JEF2.2 updating) library (JEFF3.1 not yet available)

- 3D Hexagonal model

2) MCNPX ver. 2.6.c code with ENDF/B-VI & JEFF3.1 libraries

EFIT/MgO-Pb three zone core will be described in the rev. 1 of the

Deliverable D1.6 (in progress)2


3

Main Design Requirements & Choices

Lead coolant (v 1 [m s-1]): T Inlet 400 °C – T Outlet 480 °C

U-free CERCER Fuel (PuO2, MAO2 from MOX spent fuel) in a MgO matrix

To flat the PD profile 3 Radial zones

Max Linear power f(MgO VF & Conductivity):

- with 50%* MgO VF (Fuel Intermediate & Outer) Max PL 180 [W cm-1]

- with 57% MgO VF (Fuel Inner) Max PL 200 [W cm-1]

*Lowest MgO technological content

Max Fuel operating Tmaxfuel = 1380 °C & Max clad T (SS, SA213T91)

Tmaxclad = 550 °C: since TOUT Pb is 480 °C Limited radial form factors (ffrad)

Residence time = 3 years: Pb corrosion is the most restricting condition

(in comparison to BUmax, DPAmax) Requires high fuel PD KTH Stockholm, 22nd – 23rd May 2007 , IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto


4

Transmutation Performances: “42-0” approach

Avoid Pu Burning (expensive in sub-critical reactors)

Avoid Pu Build Up (aim of the U-free choice; also for public acceptability)

Since physically is always 42 kg (HM) fissioned per TWh the approach is:

-42 kg (MA) / TWh

0 kg (Pu) / TWh

f (fuel E = 45,7%)

It does not depend on Pth (plant size), PD …

The core design for this goal has to be compatible with:

• Limited keff (t) variations ( f (fuel E) ) during the cycle

Limited Proton Current Range

• The proton accelerator performances (800 MeV, 20 mA)

E = Pu / ( MA + Pu )

MA: (Np, Am, Cm)



5

Core Design Requirements (1/2)

Pth 300-400 MWth but the size optimization criteria should be:

Min cost per kg of fissioned MAs Min cost per MW deployed

cost / MWdeployed = f(core size, accelerator size)

Because the present lack of data about the unitary costs, we assume the following semplified criterion:

Decreases by increasing Pth Could increase by increasing Pth

(also for the loose of φ*)

eff

s

s

eff

s

eff*

k

k

k1

k1

ρ

ρ

42-0 approach

The largest size core acceptable within the spallation module already designed (ANSALDO) able to evacuate 11-12 MW

The corresponding proton accelerator is: 800 MeV-20 mA



6

Core Design Requirements (2/2)

Spallation module size (19 central FAs) fixes

the FA dimension (double apothem = 191 mm)

Spallation module size, max I (20 mA - 800 MeV),

keff & Max PL Pth (plant size is an output data)

To obtain high PD (& max allowable Pth) in each fuel zone:

- PD profiles have to reach its PDmax

- ffrad as low as possible

PDmax,homFA = VFPellet * MaxPL / Rpellet2


[W cm-3] MaxPD1 MaxPD2 MaxPD3

Limit 106 96 96

BOL 98,41 94,55 96,22

BOC 98,67 94,50 95,62

EOC 96,88 94,27 95,72

Inner Interm Outer

106 [W cm-3]

96 [W cm-3]

“DesirablePerformances”

“PDmax,homFA obtained with ERANOS”

200 [W cm-1]

180 [W cm-1]


7

Radial Flattening


The subdivision in radial zones has two main goals not correlated:

1) Neutronic: to flat the Flux & PD distributions

(Since the fuel E is fixed by the 42-0 approach variation of the VFHM)

2) Thermo-hydraulic: to allow a proper different tuning of the coolant flow

(vPb 1,02 – 0,96 – 0,99 in the inner, intermediate & outer zones, respectively)

Assuming as reference the intermediate zone with 50% MgO VF (minimum)

and suitable pin & pitch, the fuel VFHM has been varied :

- in the inner zone increasing the MgO content (up to 57%);

- in the outer zone increasing the pin diameter (maintaining the 50% MgO).

because using only one flattening strategy (either pin diameter or MgO VF)

we do not achieve the same level of both flattening and PDmax values


8

Inner, Intermediate & Outer FA Design


Inner and Intermediate: Outer:

Same pin & pitch; MgO VF (57%, 50%) > Pin - Same MgO VF

(50%)


8.a

Inner, Intermediate FA Design (by ANSALDO)


8.b

Outer FA Design (by ANSALDO)


9

Deterministic Calculations (for the overall core design w/o the P th distribution in the FA pins)


ERANOS ver. 2.0 – ERALIB1 library

- Cell calculations by the ECCO code with 1968 energy groups

(heterogeneous geometry description for the fuel cells)

- Spatial calculations by the VNM-VARIANT TGV Hexagonal 3D code

- Burn Up calculations by 75 Solid FPs

Spatial & Energy distribution of the external source (n < 20 MeV)

given by MCNPX 2.5.b calculations

By fixing:

1) fuel E (for the 42-0 approach) 2) Spallation Target: Rt = 43,7 cm (19 FAs)

3) AH = 90 cm (to limit the pressure drop) 4) FA geometries

we obtain: 180 FAs to get keff (t) ≤ 0,97 during the fuel cycle

42 / 66 / 72 FAs to exploit PDmax1,2,3 (inner / intermediate / outer zones)


10

384 MWth core: H3D model & cylindrised vertical section


42

66

72


11

384 MWth core performances


[MW] Pth1 Pth2 Pth3 PthTOT Pthmax1/FA Pthmax2/FA Pthmax3/FA AvePth1/FA AvePth2/FA AvePth3/FA AvePth/FA

BOL 95,60 142,54 140,73 378,88 2,49 2,37 2,39 2,28 2,16 1,95 2,10

BOC 95,98 142,31 140,48 378,77 2,57 2,43 2,43 2,29 2,16 1,95 2,10

EOC 95,11 142,32 141,27 378,70 2,58 2,48 2,47 2,26 2,16 1,96 2,10

(*) 5 MW are dissipated in the other structural zones (proton beam excluded)

(**) ffrad is defined as the Pth ratio between the hot and the averaged FA

(*)

(**)

ffrad1 ffrad2 ffrad3 ffax1 ffax2 ffax3 fftot1 fftot2 fftot3

BOL 1,09 1,10 1,22 1,14 1,16 1,17 1,25 1,27 1,43

BOC 1,12 1,13 1,24 1,14 1,16 1,17 1,28 1,30 1,45

EOC 1,14 1,15 1,26 1,14 1,16 1,17 1,30 1,33 1,47

AvePDHomCore 70,7 [W cm-3]


11a

384 MWth core radial flattening(equivalent cylindrical model)


12

keff(t) behaviour (384 MWth, EPu = 45,7%): 200 pcm/y

keff(t) depends also on the 75 solid FPs model adopted: the gas FPs have been neglected (for their migration in the plenum). Their contribute is however of about 100 pcm.

BOL BOC EOC


384MWth (ERALIB1 Library; 75 Solid FPs; 172 -> 1968 -> 51 energy groups)

0,969

0,970

0,971

0,972

0,973

0,974

0,975

0 0,5 1 1,5 2 2,5 3

t [y]

k eff

keff

200

pcm

/ y

FA EOL

Proton Current = f (keff (t), *, Pth)

13,5 mA (almost constant)


13


Burn Up Performaces (384 MWth, EPu = 45,7%)

2400

2500

2600

2700

2800

2900

3000

0 1 2 3[ years ]

[ kg

]

Tot Pu

Tot MA

Pu / Pu (BOC) -0,7%

MA / MA (BOC) -13,9%

3 yearsBU = 78,28 MWd / kg (HM) BU -40,17 kg (MA) / TWh

Total E = 10,0915 TWhth -1,74 kg (Pu) / TWh


14


Behaviour of MA isotopes

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3

years

[ %

] Tot MA

Am241

Am243

Cm242

Cm244

Behaviour of Pu isotopes

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3Years

[ %

]

Tot PuPu238Pu239Pu242

keff increases by 200 pcm/year(in spite of the Pu239 decrease)mainly for the Am241 disappearence(by capture -, decay Pu238)

Pu, MA vectorsEvolutions


15


15

Am241 Microscopic Cross Sections

1,0E-04

1,0E-02

1,0E+00

1,0E+02

1,0E+04

1,0E-09 1,0E-08 1,0E-07 1,0E-06 1,0E-05 1,0E-04 1,0E-03 1,0E-02 1,0E-01 1,0E+00 1,0E+01 1,0E+02

Energy [ MeV ]

[ cm

-2 ]

Fission

Capture

AveE 0,5 MeV Captures exceed Fissions

[bar

n]


16


BOC Monte Carlo Calculations (for the overall core design with the P th distributions in the FA pins)

keff 0.97403 0.00023

Neutron source (S)

(neutrons/proton) 23.02 0.08

M = all fission neutrons / S 19.45 0.25

kS = M / (M+1) 0.95111 0.00059

0.52

Proton current 13.2 mA

SS

effeff

kk

kk

/)1(

/)1(*

BOC condition -

ERANOS results:

keff = 0.97094

ks = 0.95328

* = 0.61

I = 13.5 mA

(ERALIB1)

Reference values for Pth deposition calculations at BOC (800 MeV p+):

- LA150h proton library when Ep+ < 150 MeV

- CEM03 physics model when Ep+ > 150 MeV

- CEM03 physics model when En > 20 MeV (e.g. fuel) or En > 200 MeV (Pb)

- JEFF 3.1 library (Pb, MgO, SS) when En < 20 MeV (e.g. fuel) or En < 200 MeV (Pb)

- ENDF/B-VI library (fuel) when En < 20 MeV

p+

n


17

BOC: comparison between ERANOS & MCNP results


ERANOS MCNPX 2.6.c

ERALIB1 JEF2.2JEFF3.1

with URR*

JEFF3.1**

no URR

JEFF3.1 + ENDF/B-VI

for fuel

JEFF3.1 + LA150h

for Pbkeff 0.9709 0.9633 0.9620 0.9616 0.9740 0.9646kS 0.9533 0.9413 0.9320 0.9297 0.9511 0.9349

*

0.61 0.61 0.54 0.53 0.52 0.53

I [mA] 13.5 17.2wrong

URR tables19.2 13.2

Pthmax / FA

(inner zone)2.57 2.79

wrong

URR tables2.86 2.46

* URR = Unresolved Resonance Region

If we assume a keff reference value of 0.97: - MCNPX with JEFF3.1 (Pb, SS, Pb) + ENDF/B-VI (for fuel) - ERANOS with ERALIB1 represent our “best estimate” for the Pth deposition

I = f (keff, *, Pth)with keff = 0.96 gives not correct Pth values in theinner hot pins

** Missing transport for some HMs


18


1) The core has been designed by a deterministic code

2) The Pth distribution has been obtained with MCNP: heterogeneous description (pin detail), geometry dilatation and n libraries at working T

3) The different libraries influence the keff values and, as a second order effect, the Pth distributions

4) Independently from the calculation code and library, the “real” keff level is 0.97 (at the moment)

5) For a realistic estimation of the max PL (near the external source) the MCNP Pth distribution results has to be obtained at keff = 0.97 in order to correctly evaluate the contribution of: - the external source - the sub-critical core

6) The “best estimate” of the max PL is obtained by a Monte Carlo code and library that gives keff 0.97 (on the core defined with deterministic methods)

Chosen procedure

19


Pth at BOC [MWth] MCNPX (*)

Inner zone

(42 FA) 94

Intermediate zone

(66 FA) 140

Outer zone

(72 FA) 141

Out of the FA 10

Total 384

(*) By excluding the spallation module and beam pipe zones (**) By including the n contribute on spallation module and beam pipe zones ( 0,7 [MW])

ERANOS (**)

96

142

140

5

384

Pth deposition Comparison between ERANOS & MCNP results


20


OUTERZONE

MCNP analysis of Pth deposition in all the FAs

21


OUTERZONE

Possible improvements of the Pth distribution

- Possible improvements of the radial Pth flattening by re-arranging the interface between the different zones (closer to a “circular” shape)

2nd zone FA

3rd zone FA

2nd zone FA

22

MCNP analysis of the average FA Pth in the 3 zones ( < 1.8%)


Average Pth

in FA

[MW]

Average Pth in fuel pellets

[MW]

Axial form factor in the average

FA

Inner zone 2.23 2.06 1.14

Interm. zone 2.12 1.98 1.17

Outer zone 1.96 1.84 1.17

Axial distribution in the AVERAGE FA in the INNER ZONE.Linear power is here: power in zone / (n. of assemblies) / 168 pins / cm.

100

110

120

130

140

150

160

170

180

-45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45

z (cm)

W /

cm

Pb levelNo-symmetryaround the coremid-plane (z=0) because of theexternal source


Axial distribution in the hot FA in INNER ZONE.Linear power is here: average in FA/168 pins.

110

120

130

140

150

160

170

180

190

-45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45

z (cm)

W /

cm

23

MCNP analysis of the hottest FA in the 3 zones ( < 2.5%)


Pb level

(about 6-8% of the Pth is outside of the fuel pellets)

Max Pth

in FA

[MW]

Max Pth

in the fuel pellets

[MW]

Hottest pin in hot FA

(pellet)

[kW]

Axial form factor in

the hot FA

Hottest pin / average

pin

(hot FA)

Max linear power in

pin [W/cm]

Inner zone 2.46 2.28 16.4 1.13 1.21 203

Interm. zone 2.35 2.19 13.7 1.18 1.05 177

Outer zone 2.43 2.29 15.0 1.20 1.10 197

In ERANOSthe limit of180 [W cm-1]is respected(because of the homogeneous FA description w/o the pin details)

24

Concluding Remarks

42-0 approach for MAs transmutation (without Pu burning and production)

by a 400 MWth Pb cooled ADS is a viable strategy:

- the lowest keff during the fuel cycle is compatible with the 20 mA current limit

- the keff(t) swing is 200 pcm / y Limited proton current range

The calculated performances (keff, proton I, PL peak, etc…) depend “strongly”

on the adopted nuclear data libraries (JEF2.2, ERALIB1, JEFF3.1, ENDF-B.VI)

The limits on the clad T seem to be respected by the subdivision in 3 radial zones

(w/o orificing in the same zone)

The PL results (hottest pins) are very close to the design constraints (mainly in the

outer part). Eventually the problem could be faced by re-arranging the interface

between the different fuel zones and the core size (to maintain the same keff)

In the revision 1 of the deliverable D1.6 (in progress):

- the analysed design of the EFIT/MgO-Pb core will be addressed as reference;

- the possible improvements (Pth distribution) will be indicated. KTH Stockholm, 22nd – 23rd May 2007 , IP EUROTRANS DM1-WP1.5 Meeting M. Sarotto


Supplementary

S1

Pu & MA Isotopic Compositions

MOX spent Fuel after 30 years’ cooling( CEA )

Pu [ w % ]

Pu238 3,737

Pu239 46,446

Pu240 34,121

Pu241 3,845

Pu242 11,850

Pu244 0,001

MA [ w % ]

Np237 3,884

Am241 75,510

Am242 3,27E-06

Am242m 0,254

Am243 16,054

Cm242 2,3E-20

Cm243 0,066

Cm244 3,001

Cm245 1,139

Cm246 0,089

Cm247 0,002

Cm248 1,01E-04

Pu Vector

Pu238

Pu239

Pu240

Pu241

Pu242

Pu244

MA Vector91,8% Am4,3% CmNp237

Am241

Am242

Am242m

Am243

Cm242

Cm243

Cm244

Cm245

Cm246

Cm247

Cm248

Pu Vector


A

B

C

S2

After the first 3 years:

Before refuelling the average residence t is 2 years

After refuelling the average residence t is 1 year

Years A B C

0 0 0 0

1 1/0 1 1

2 1 2/0 2

3 2 1 3/0

4 3/0 2 1

5 1 3/0 2

6 2 1 3/0

7 3/0 2 1

8 1 3/0 2

9 2 1 3/0

Refuelling

We consider: - the keff behaviour, core performances… between 1 (BOC) and 2 (EOC) years

- the BU results (without refuelling) at the 3rd year

We have approximated: the “actual situation” that gives an average residence t of x years

with an entire core that has burnt for x years without refuelling

Fuel cycle hyphotesis

For Pb corrosion (strongest requirement):

3 years as max residence time

Refuelling of 1/3 core each year


S3

Two radial fuel zones

Radial Flattening Technique

Fu

el_I

nne

r

Fu

el_O

uter

R1 R2

Tar

get

Rt

Different MgO matrix contents(fabrication more expensivefor supplementary line cleaning)

Different Pin diameters(less efficient because in the outer zone the max coolant outlet T is reached before reaching the max allowed linear power & PD)

StructuralC o o l a n tF u e l

Pu

+M

A

Mat

rix

StructuralC o o l a n tF u e l

Pu

+M

A

Mat

rix

MgO VF OUT = 50%

MgO VF IN = 57%

BREST Style


S4

Kg/TWhMA Pu

- 42 0

Pu

Bu

rne

r

Pu

Bre

ed

er

0

k e(pcm/y) (%)

%MgO50 54

I (mA, 800 MeV)

1032

50 -36 -6

E=5

0%

E=50%

R (

cm)

P

200

20

E=27%E=27%

E=50%

-65 +23

E=27%E=27%

E=27%

K swing

E=45.7%

E=45.7%

1900 27

E=45.7%

400optimization

optimization

optim

izatio

n

1316

57

/50

/50

200

IP EUROTRANS WP 1.5 Safety Meeting KTH - Stockholm, May 22 nd – 23 rd 2007 Neutronic Design of the...

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