Oxide fuels and targets fortransmutation
F. Sudreau,
J.M. Bonnerot, E. Brunon, D. Warin,
G. Gaillard-Groléas, M.P. Ferroud-Plattet

Nuclear Energy Division
F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 2006

1Introduction•Direction 1 of the Act dated 30 December 1991 on themanagement of High Level, Long-Lived radioactive waste¾ Explore solution to separate and transmute them into stableelements or elements with much shorter half-life• Main radioactive elements
9 Fission Products: Caesium, iodine and technetium
9 Minor Actinides: Americium, Neptunium, Curium•

CEA launched a vast programme to demonstrate thescientific and technical feasibility of minor actinidetransmutation:– In MOX fuels (homogeneous method) in PWR and Sodiumcooled fast reactor– On Inert Matrix support (heterogeneous method)– In Sub-Critical reactor dedicated to transmutation

F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 2006

2

Evaluation of Homogeneous Transmutation in a PWR• Simulations made in 2002 :Pu/ML (%)
U5/U (%)
AM/ML (%)
BurnupTaux decombustion
Xe+Kr(mm33/g/g ox)ox)
Xe+Krproduced
produit (mmHe(mm33/g/g ox)ox)
He produced
produit (mmInternal Pressure
Pression
à chaud (bar)(bars)MOX
MOX-UE
9,026
80,25
4,30
1,136060 GWd/tHM
GWj/tML
1250
110
105

1400
510
213

Above 100 mm3/g, He
is fully releasedÖ Internal pressure incompatible with the current design of EPR rods
(but there is no experimental data on gas release for MA fuels in PWR)

Ö Possible solutions
9 Reduce the americium content (around 0.5 %)9 Reduce the initial internal He pressure into the rod (efficiency against Herelease ?)9 Reduce the height of the fuel column (5 % : Impact on the reactor
functioning to be evaluated)
F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 20063

Evaluation of Homogeneous Transmutation in a FNR•

Nacre– A SuperPhénix S/A including Np(2%) in the fuel has beensuccessfully manufactured•

Trabant (CEA, ITU, FZK)

– Irradiation in HFR (Pu = 40 % andNp = 5 % ; BU = 9.3 at%)Ö Fuels containing neptunium behave
as satisfactorily as the standard SFRfuel•Trabant

SUPERFACT 1 (CEA, ITU)

– Irradiation in PHENIX (Am = 2%and Np = 2 % ; BU = 6.5 at% ;Transmutation rate for MA = 30 %)Ö First pin scale demonstration of thetechnical feasibility of thehomogeneous-mode transmutationof the minor actinides in FNRSUPERFACTF. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 2006

4

Transmutation in Heterogeneous mode
Inert Matrix: Introduction• Dilution of MA into Inert Material = Target
ÖMA content : 1.5 to 2.5 g.cm-3ÖMain issues to be studied
9Materials : actinides compound and inert matrix9Damages due to FP recoil
9Excessive swelling due to He production• Materials for inert matrix
9High Thermal conductivity after material damaging
9Low swelling induced by neutrons and FP damaging
9High melting point
9No chemical interaction with actinide compounds, clad and coolant
Ö First selection (Bibliography, out of pile measurements):
MgO, ZrN, TiN, Cr, V, Mo, Al2O3, MgAl2O4, Y3Al5O12, St-ZrO2, CeO2
Compatible with Sodium

Compatible with WaterÖ Irradiations
9Inert Matrices alone (neutron damaging): T2bis, SANTENAY, MATINA 1A
9Inert Matrices with Fissile Compound (FP damaging): T3, THERMET, MATINA 1A
F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 2006

5Transmutation in Heterogeneous mode
Synthesis of first MATINA 1A results:
Swelling of inert matrices due to a fast fluence = 6.1026 neutrons.m-2
Gonflementvolumique(%)
Swelling(percentin volume)
12,00

11,3

Confirmation of the largeswelling of alumina but
disagreement with Neeft
Law

10,00
8,00
6,00

First result onmagnesia atsuch aneutron
fluence (6 1026
m-2 against 2 1026)

Low swelling ofspinel in good
agreement withprevious results

4,00

Excellent stability ofrefractory alloys

2,52,00
0,50,40,3-0,1WNbCr

0,00
MgO

MgAl2O4

F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

Al2O3

September 2006

6Transmutation in Heterogeneous mode

Volumic swelling (%)

Swelling of alumina under fast neutron flux : synthesis

No saturation of the swelling
Disagreement not yet explained
Field of the Neeft Law
Fast fluence (1026 m-2 ; E>0,1 MeV)

F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 2006

7

Transmutation in Heterogeneous mode
Synthesis of first MATINA 1A results:
Swelling due to neutron flux and Fission Products damages
Swelling (percent in volume)• Fission Products Damaging process is different from a matrix to another• It seems
9 MgO :
Sensitive to FP damaging
9 MgAl2O4 : Good stability at high temperature
9 Al2O3 :Positive effect of the temperature (1400 °C with UO2 against
550 °C without UO2) : Damage annihilation ?
F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 2006

8

Transmutation in Heterogeneous mode
Swelling of magnesia due to neutron flux and Fission
Product damages : synthesis• MATINA 1A and BORA-BORA are results obtained by the CEA in 2005
• New BORA-BORA results expected in 2006 (BUvol = 300 GWj.m-3)
Ö Confirmation of the swelling “saturation” ?
Cibles à matrice magnésie
Swelling(percent in volume)

Gonflementvolumique(%)
Swelling(percentin volume)

12
10

T3 pin7T3 pin58

MATINA 1
BORA-BORA

6

MATINA 1A4macromasses
20050

100150200-23Buvol (GWj/m)
Taux de combustion
volumique(GWj/m3)

F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 2006

9Transmutation in Heterogeneous mode
Technical feasibility : ECRIX

Demonstration of the technical feasibility
Ö Irradiation in representative conditions(coolant, neutron spectrum, …)
Ö ECRIX Irradiation
9 In Phénix, from March 2003 to March 2006
9 AmO1.6 micro dispersed into MgO
9 Am = 0.7 g.cm-3 (2.75 g of Am in 200 mm
height column)
9 Objective Fission Rate = 30 at% (≈ 90 %Transmutation Rate) Æ 35 at% haveprobably been reachedÖ PIE results will probably allow to increase
the performance of magnesia targets: Am
amount and fission and transmutation
rates
F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

Target

Thermo mechanical Model

September 2006

10Transmutation in Heterogeneous mode
ECRIX : Irradiation historicTransmutation rate
Fission rate

Reactor shutdown from 08/08/04(end of cycle 51) to 12/12/04(beginning of cycle 52)

34 %Duration (EFPD)
F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

Duration (EFPD)
September 200611

Transmutation in Heterogeneous mode
Inert Matrix : Main achievements¾ Selection of the most promising materials
9 MgO for FR
9 (Zr,Y)O2 for PWR, FR…
9 MgAl2O4 discarded at low or intermediate temperature(amorphization)¾ FP damaging: Possible solutions
9 High temperatures (1000 – 1200 °C): allow damage annealing
9 Macrodispersion: Actinide compounds dispersed under the form of
100 μm particles could limit the damaging of inert matrix¾ He retention and swelling
9 After results from T4 and T4bis experiments (high swelling due to He
bubbles accumulation in spinel)ÎResults from ECRIX (34 % of Am transmutation rate in MgO)ÎDevelopment of porous target (HELIOS irradiation in HFR)ÎTarget operating at high temperature (T > 1000°C)
F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 2006

12

Transmutation in dedicated mode
¾Fuel Design Criteria
9 Multi-recycling : Average BU = 20-30 at%
9 High MA content : > 3 g TRU/cm3 & degraded Pu
9 Inert matrix volume fraction > 50 vol%• To make easier the manufacturing• To keep the benefit of the inert matrix properties¾BORA-BORA
9 Irradiation in BOR60 : 60 % PuN/ZrN ; 40 % PuO2/MgO ;B.U. = 11 at%
Ö PIE results : Good behaviour of the fuel element (pellet andcladding)

9 Irradiation extension : 18.8 at% BU Ö PIE in progress¾FUTURIX/FTA (CEA-DOE-ITU-JAERI)
9 Irradiation in Phénix from 2007 to 2008
9 8 types of fuel irradiated in the same conditions :9 2 Metallic with sodium bond (up to 1.2 g.cm-3 of Am)
9 2 Nitride with sodium bond (up to 2.7 g.cm-3 of Am)
9 2 Oxide CER-CER (MgO) Composite (up to 2.0 g.cm-3 of Am)
9 2 Oxide CER-MET (Mo) Composite (up to 1.0 g.cm-3 of Am)
F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 200613

Conclusion••Transmutation in Homogeneous mode : SUPERFACT 1 is a first pin
scale demonstration of technical feasibility
Transmutation in Heterogeneous mode :¾ Today– MgO confirmed at the reference matrix, ZrO2 (and Mo92) is an alternative– MgAl2O4 is discarded: not stable enough under irradiation at low Temp.
– ECRIX (Irradiation including Am): NDE are underwayÖ Demonstration of the pin scale technical feasibility¾ From 2008 to 2010 : Last Phenix Irradiations and PIEÎPerformance of the microdispersed concept: ECRIXÎInfluence of the target microstructure on FP damaging: MATINA 2-3 andCOCHIX
ÎPerformances of the zirconia matrix: MATINA 2-3 and CAMIXÎInfluence of high temperatures on damage annihilation: MATINA 2-3•

Transmutation in sub-critical dedicated reactor Æ FUTURIX/FTA– Irradiation: from 2007 to 2008
– PIE: from 2009 to 2010

F. Sudreau – Fuel Department
9 IEM Partitioning and Transmutation

September 2006

14