Minor Actinides Transmutation in both ADS and Power Fast Reactors

Carlo Artioli Nuclear 2011 Pitesti 26 May 2011

Nuclear 2011

Piteşti

May 25-27, 2011

Minor Actinides Transmutation:

ADS and Power Fast Reactors

Carlo [email protected]

- Wastes and Minor Actines

- EFIT, the ADS of EU EUROTRANS Project (Lead coolant)

- 42-0 concept and performances

- Interdependency among main EFIT parameters

- A way for avoiding Minor Actinides net production (Gen IV)

- Close cycle and adiabatic core (LEADER project)

- Dynamic equilibrium composition

- Material Balances

- Core designing sequence (2NP Design)

-Adiabatic core used as MA burner

- Conclusions

Outline


Wastes and Minor Actines

TRUs, Minor Actinides(MA) and Pu, are the major contributors to the long lived wastes

Considering and using Pu as a fuel, an important work must be devotedto “solve” the MA problem

As far as the MA legacy, both present and to be built up, is concerned:-their incineration, meantime producing energy, is a promising solution

While for the future could rely on:-a close cycle, without any MA net production

Sketches of both are presented in the frame of the Lead cooled systems:

-An ADS (Accelerator Driven System) for an intensive burning of the MA legacy,-A so called “adiabatic” ELSY-Type for achieving a theoretical zero net

production of MA


EFIT, the ADS of EU EUROTRANS Project

Within the EUROTRANS Project (EU 6th FW)

the EFIT ADS(European Facility for Industrial Transmutation)

has been designed

Features:

-Lead coolant

-Power 400 MWth

-Fuel: Pu+MA oxide in inert matrix (MgO or Mo)

-Accelerator: 800 MeV protons, i<20 mA

In the EUROTRANS Project (EU 6° FW)

the EFIT ADS

(European Facility for Industrial Transmutation)

has been designed

Features:

-Lead coolant

-Power 400 MWth

-Fuel: Pu+MA in inert matrix (MgO or Mo)

-Accelerator: 800 MeV protons, i<20 mA



42-0 concept and performances

Transmutation

Transmutation

fission fission

PuMA High enrich.

PuMA

Transmutation

Transmutation

fission

Low enrich.

Low MA transmutationMA decreases slightlyor even increases

(Pu burner)

High MA transmutationMA decreases stronglybut not only by fission

(Pu breeder)

FUEL


FUELe =

Pu

/(P

u+

MA

)

%MgO

50

50( %fuel )

Pu

mass B

ala

nce

MA

mass b

ala

nce

- 42 0

Pu

bre

ed

er

Pu

bu

rner

Kg

/TW

h

Ex.

- 60, +18

Ex.

- 30, -12

Approximation:

No effect on the spectrum by the variation

of the matrix fraction (in the range)


Total balance 42 kg / Twhth

PuMA

Tra

nsm

uta

tio

ns

Fission product


PuMA

X kg/TWh of net Transmutations

FP, 42 kg/TWh


Pu

mass B

ala

nce

MA

mass b

ala

nce

- 42 0

Pu

bre

ed

er

Pu

bu

rner

Kg

/TW

h

Ex.

- 60, +18

Ex.

- 30, -12

In EFIT we want:

- No new Pu production (what would be contradictory with the inert matrix choice)

- No Pu burning (what would be economically disadvantageus)

therefore a Pu balance = 0 , that implies a MA balance = -42

Suitable e = Pu / (Pu+ MA)


INPUT

to be supplied

OUTPUT

Pu and MA vectors

Search of suited

Pu/ (Pu+MA)

Pellet composition

Pu, MA dioxyde

stoichiometry and density;

Matrix, density and fraction

Definition of “enrich.”

Pu/ (Pu+MA)

Pin geometry definition

(diameter and other by guess)

Gas releases

= f (T, BU)

Fuel element definition

Max linear power, TH(Tmax, conductivity law)

Fuel density power

Core density powerKeff required

Core definitionCore size and power

Verification a

nd o

ptim

ization

Main statement:

DESIGN

42 - 0



42

66

72


Hom. Power density at midplane

Maximum allowed, corresponding to linear power rating 207 and 180 W/cm

(calculations: M. Sarotto)




DPu / Pu (BOC) -0,7%

DMA / 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

With the definitive right enrichment we have the balances:MA: 41.9 kg/TWhth

Pu: 0 kg/TWhth

… but …

2400

2500

2600

2700

2800

2900

3000

0 1 2 3[ years ]

[ kg

]

Tot Pu

Tot MA

MA and Pu balances



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 Pu

Pu238

Pu239

Pu242

Pu, MA vectors evolutions

DPu / Pu (BOC) -0,7%

DMA / 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

2400

2500

2600

2700

2800

2900

3000

0 1 2 3[ years ]

[ kg

]

Tot Pu

Tot MA

MA and Pu balances

The Pu and MA vectors evolve in the time towardequilibrium configurations; this implies:

- Calculation of the final enrichment with theequilibrium vectors

- Enrichment resetting in the transitory phase


42- 0 approach

- ONE fission corresponds ONE MA “atom” fissioned,either directly or indirectly (Pu acts as “ catalyzer”)

-the MA burning efficiency is 41.9 kg/TWhth,i.e. about 120 kg of MA/y (400 MWth, load factor 0.8)

- meantine there is a net power productionof about 100 MWe



Interdependency among main EFIT parameters


A way for avoiding Minor Actinides

net production (Gen IV)

No net production of Pu and MA via close cycle


For operating in a close cycle the reactor (core)must be an “adiabatic” one, which means ablenot to exchange “significant” materials withthe environment.

Both on the front and back end

Close cycle and adiabatic core


■ Two different mathematical approaches have been developed for the solution of the equilibrium vector (recursive and matricial)■ The results have been validated by 2 codes: MCNPX and FISPACT

Reaction channelsC. Artioli, G. Grasso and C. PetrovichA new paradigm for core design aimed at the sustainability of nuclear energy: the solution of the extended equilibrium state. Ann. of Nucl. En. 37:915-922 (2010).

Dynamic equilibrium composition



-

j

tr

ijijeatN )( jjjrwith

U 82.1%

Pu 17.0%

MA 0.9%

total 100%

238Pu 2.1%239Pu 57.3%240Pu 34.0%241Pu 3.3%242Pu 3.3%243Pu 0.0%

100%

Recursive Integration Method

Every isotope can be expressed as:

The coefficients aij are found integrating recursively the Batemanequations with the requirement that the amount of everyisotope does not change after some irradiation time (e.g. 5 years) and cooling time (e.g. 4 years)

On the ELSY-Typespectrum



1.0E+05

1.2E+05

1.4E+05

1.6E+05

1.8E+05

2.0E+05

2.2E+05

2.4E+05

2.6E+05

0 1 2 3 4 5 6 7 8 9

mas

s (g

ram

s)

years

Pu238 -MCNPX

Pu242 -MCNPX

Pu241 -MCNPX

Am241 -MCNPX

Cooling time

ELSY

[LF

R, 1

50

0 M

Wth

] U 82.1%

Pu 17.0%

MA 0.9%

total 100%

238Pu 2.1%239Pu 57.3%240Pu 34.0%241Pu 3.3%242Pu 3.3%243Pu 0.0%

100%


Theoretical equilibrium fuel cyclefor 1500 MWth LFR (ELSY-type)

Material Balances

Considering 0.5% losses in the reprocessing:- in the waste there are also: 25 kg/y U, 6 kg/y Pu , 0.3 kg/ MA;- fed U must be 580 kg/y


Material Balances

Theoretical equilibrium fuel cycle for 1500 MWth LFR (ELSY-type)

Despite the fact that the Adiabatic LFR acts as a “pure” U fissioner,fission reactions occurs on all the component, i.e. U, Pu and MA

MA rate of actual fissioning (1g/Gwhe) is rather low:infact the greatest part (4 g/Gwhe) of their “disappearing” rate (5 g/Gwhe) occurs by fissioning indirectly via Pu ;This accounts for a smooth sensitivity of beff to the MA content.


Material Balances

Theoretical equilibrium fuel cycle for 1500 MWth LFR (ELSY-type)

Such a core can be operated as adiabatic (i.e. removing from the waste only Fission Product and adding in fabrication equal amount of U) even when the equilibrium composition is not reached yet.The natural evolution toward the equilibrium implies for ELSY a variation of reactivity of some 600 pcm, to be compensated with 2-3% of fuel elementsor devoted absorbers.

How to deal with the reactor not at equilibrium?

Such a core can be operated as adiabatic (i.e. removing from the waste only Fission Product and adding in fabrication equal amount of U) even when the equilibrium composition is not reached yet.The natural evolution toward the equilibrium implies for ELSY a variation of reactivity of some 600 pcm, to be compensated with 2-3% of fuel elementsor devoted absorbers.


Core designing sequence (2 NP Design)

U/Pu/MA equilibrium

(guess spectrum)

- Thermal conductivity

- Max allowed Temperature (Tc)

Linear power Admitted (Plin)

Thermo-hydraulics constraints:

- Max cladding temperature

- Coolant outlet temperature (Tout)

- Coolant Volume Fraction

Thermo-hydraulics constraints:

- Inlet-outlet temperature (Tin , Tout)

- Pin diameter

Elementary Cell Defined

(guess spectrum)

YES

Possible to design critical facility

by gathering as many cells are required to reach keff=1

Once criticality reached

PRELIMINARY CORE

(preliminary spectrum)

Kinf> 1 ?NO

No viable solution for adiabatic

or

Rearrange volume fractions

keeping the fuel composition

fee

db

ack

feedback ADIABATIC CORE DEFINED

SIZE AND POWER


Adiabatic core used as MA burner

MA

Introduction of new MA in the fuel, other than the equilibrium ones induces their net burning (by fission either directly or via Pu).

Evolution is roughly exponential toward their equilibrium concentration.Rate of burning is depending on their overload over the equilibrium



C0 equilibrium ratio(depending on the spectrum and not on the flux intensity)

C0 =5

t

5%MA

Pu

Ci =8Ci ,initial concentration, must be optimized

C5y =7

τ (depending on both flux intensity and spectrum)

Data: ELSY [LFR, 1500 MWth]

τ = 12 y

%MA

Pu

P&P Code

EOL=5y (BU peak = 100 MWD/kg)

Incr

easi

ng

dif

ficu

ltie

s o

nre

pro

cess

ing

an

d f

ab

rica

tio

n



Balance (example)Ci = 8 % MA loaded (as hypothesis) 480 kg

C0 = 5 % MA equilibrium concentration 300 kg

C5y = 7 % unloaded MA 420 kg

Burnt MAs amount (5y) 60 kg (12 kg/y)

MA quantity to be reprocessed = 7 % 420 kg

MA losses in reprocessing = 0.5 % of 420 kg 2 kg

Actual Losses (Losses/Burnt) = 2kg/60kg 3 % (the same for EFIT)

C0 equilibrium ratio(depending on the spectrum and not on the flux intensity)

C0 =5

t

5%MA

Pu

Ci =8Ci ,initial concentration, must be optimized

C5y =7

τ (depending on both flux intensity and spectrum)

Data: ELSY [LFR, 1500 MWth]

τ = 12 y

%MA

Pu

P&P Code


Incr

easi

ng

dif

ficu

ltie

s o

nre

pro

cess

ing

an

d f

ab

rica

tio

n

t

5%MA

Pu

%MA

Pu


87

5



Performance improving (example)Performances can be improved by both:

-Increasing the MA overloading (reprocessing & fabrication problem!)

-Increasing the BU (modest effect)

For example:

-Increasing the BU by 50% (!), the MA burning rate increases by 13%

from 12 to 13.5 kg/y

- increasing the allowed MA concentration by 50% (from 8 to 12%), the MA burning rate increases by 140%, from 12 to 29 kg/y

t

5%MA

Pu

%MA

Pu


87

5


Conclusions 1 / 2 (legacy)

1) MA produced by present and short term future reactors, as significant contributors to the waste loads, can be fissioned (either directly or indirectly) in ADS systems.

2) Maximum real efficiency is reached in the 42-0 concept and is about42 kg/TWhth; higher figures mean that the exceeding part has been transmuted in new Pu and not “fissioned”.

3) EFIT (EU 400 MWth ADS, lead cooled, oxide in inert matrix) has been pre-designed within the EU 6thFW.

4) Main challenges are about the accelerator (800 MeV proton, i=16 mA)and fabrication/reprocessing of such a fuel.


1) Implementing a close cycle, waste would content only FissionProducts (and U, Pu, MA lost in reprocessing).

2) Gen IV Adiabatic reactor keeps constant the amount of TRUs, soacting as a pure U fissioner.

3) To obtain this goal the appropriate composition of fuel, equilibriumfuel, has to be calculate as first step and kept in the core design.

4) In any case the available fuel will evolve toward the equilibriumcomposition.

5) Evolution from the “initial” fuel toward the equilibrium one can behosted in the same core (removing 2-3% of fuel elements or adding absorbers).

6) Capacity of burning MA legacy, even not huge, is not negligible.

7) Main challenges are in the fabrication and reprocessing of such a fuel (U 82%, Pu 17%, MA 1% with important quantity of Cm).

Conclusions 2 / 2 (future)


Some referencesArtioli, C., 2007. A-BAQUS; a multi-entry graph assisting the neutronic design of an ADS. Case study:

EFIT. In Fifth International Workshop on the Utilisation and Reliability of High Power Proton Accelerator

(HPPA 5), Mol, Belgium, May 6-9.

Artioli, C., Chen, X., Gabrielli, F., Glinatsis, G., Liu, P., Maschek, W., Petrovich, C., Rineiski, A., Sarotto,

M., Schikorr, M., 2008. Minor actinide transmutation in ADS: the EFIT core design. In International

Conference on the Physics of Reactors (PHYSOR 2008), Interlaken, Switzerland, September 14-19.

Artioli, C., Grasso, G., Sarotto, M., Monti, S., Malambu, E., 2009. European Lead-cooled SYstem core

design: an approach towards sustainability. In International Conference on Fast Reactors and Related Fuel

Cycles: Challenges and Opportunities (FR09), Kyoto, Japan, December 7-11.

Bateman, H., 1910. Solution of a system of differential equations occurring in the theory of radioactive

transformations. Proc. Cambridge Philos. Soc. 15, 423-7.

Cinotti, L., Smith, C.F., Sienicki, J.J., AÃ¯t

Abderrahim, H., Benamati, G., Locatelli, G., Monti, S., Wider, H., Struwe, D., Orden, A., 2007. The

potential of the LFR and the ELSY Project. In 2007 International Congress on Advances in Nuclear Power

Plants (ICAPP â€™07), Nice Acropolis, France, May 13-18.

DOE-GIF, 2002. A Technology Roadmap for Generation IV Nuclear Energy Systems. Technical Report

GIF-002-00, GIF.

Fensin, M., Hendricks, J., Anghaie, S., 2008. MCNPX 2.6 depletion method enhancements and testing. In

International Conference on the Physics of Reactors (PHYSOR 2008), Interlaken, Switzerland, September

14-19.

Forrest, R.A., 2001. FISPACT-2001: User manual. Technical Report , EURATOM/UKAEA Fusion

Association.

Grasso, G., Artioli, C., Monti, S., Rocchi, F., Sumini, M., 2008. On the effectiveness of the ELSY concept

with respect to Minor Actinides transmutation capabilities. In Tenth Information Exchange Meeting on

Actinide and Fission Product Partitioning and Transmutation (IEMPT10), Mito, Japan, October 6-10.


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Minor Actinides Transmutation in both ADS and Power Fast Reactors

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