1. MIXED OXIDE (MOX) FUEL FABRICATION FOR BWR TARAPUR
Sudhir Mishra  
Radiometallurgy Division, Nuclear Fuels Group
Bhabha Atomic Research Centre, Mumbai
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

2. Outline What is MOX fuel ? Plutonium as a fuel material
Why recycle Plutonium in thermal reactor?
Irradiation experience of MOX fuel
Fabrication of MOX Fuel
Conclusions
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

3. What is MOX (Mixed Oxide) Fuel ?
MOX is solid solution of PuO2 in either UO2 or ThO2 matrix
Two types of MOX fuel
(U,Pu)O2
(Th,Pu)O2
Conventional Fuel for Light water reactor-
Enriched UO2
However more than 45 light water reactors in
Europe (Belgium, Switzerland, Germany and
France) are licensed to use MOX.
So far about 2000 tones of MOX fuel has been
fabricated and loaded into power reactors.
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

4. Characteristics of Plutonium as Fuel
Pu has better neutronic characteristics for use in fast breeder reactors because of
Higher number of neutrons produced per fission in fast spectrum
Almost all the isotopes of Pu have significant cross section in fast spectrum.
Thermal Spectrum
Fast Spectrum
Recommended Spectrum
Pu239
2.11
2.33
Fast
U235
2.07
1.88
Thermal
U233
2.29
2.27
Either (Thermal)
Thermal Spectrum
Fast Spectrum
Recommended Spectrum
αPu239
0.36
0.26
Fast
αU235
0.17
0.29
Thermal
αU233
0.09
0.12
Either (Thermal)
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

5. Neutron Physics Characteristics of Pu in Thermal Reactors
Pu isotopes have higher resonance absorption cross section at low energy leading to spectrum hardening- reduction in control rod worth
Delayed neutron fraction:
Pu239 and Pu241 have smaller delayed neutron fraction - affects reactor core kinetics/transient behavior.
Pu239 has lower delayed neutron fraction than Pu241- use of research reactor Pu affects reactor core kinetics more
Fissile nuclide
235U
239Pu
241Pu
Delayed neutron fraction
0.0065
0.0020
0.0053
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

6. Why Recycle Pu in Thermal Reactors?
International
Delay in fast reactor programme giving rise to surplus Pu in some countries
A return for investment made in reprocessing facilities
Storage of Pu is not only expensive but counter productive
Disposition of Pu of military origin
India
Alternate Fuel for BWR (TAPS)
High burn-up fuels for thermal reactors and reduction of spent fuel volume and fuel cycle costs
Initiate thorium fuel cycle
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

7. MOX fuel property affecting performance
1. Thermo physical property
Marginal decrease in M.P.
Decrease in thermal conductivity.
Higher plasticity/creep
2. Behaviour of MOX fuel
Higher fission gas release
Less PCMI
Fuel is having higher oxidation potential
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

8. Homogeneity issue in MOX fuel
MOX fuel is made generally with mixing/milling route and is not as homogeneous as natural U or enriched U oxide fuel.
Pu rich agglomerate upto few hundred microns only can be tolerated as otherwise it can lead to:
hot spot generation on clad surface if present near the surface.
in case of transient, the Pu rich particle can get dislodged from the surface and act as high velocity projectile damaging the clad.
increased fission gas release.
difficulty in dissolution during reprocessing.
Uniform distribution of Pu in UO2-4%PuO2 matrix
Non-Uniform distribution showing Pu rich particles
Alpha Autoradiograph
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

9. Indian Experience on fabrication and irradiation
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

10. AC-4 cluster (Lower tier) AC-4 cluster (Upper tier)
Arrangement of Fuel Pins in fuel cluster for PWL Irradiation
Structural rod
TP-1
TP-2
TP-3
TP-4
TP-5
TU-8
Structural rod
TP-6
H-1
TP-7
H-2
TP-8
H-3
UO2Fuel pin
U-Pu MOX Fuel pin
He filled pin
AC-3 cluster
AC-2 cluster
Structural
rod
M-11
H-12
M-7
H-8
M-9
H-10
Structural rod
M-5
H-6
M-1
H-2
M-3
H-4
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019
AC-4 cluster (Lower tier)
AC-4 cluster (Upper tier)

11. Experimental MOX Fuel Irradiations in Research Reactor CIRUS (TAPS type)
Cluster No.
Peak Linear Rating (W/cm)
Burn-up
(MWd/T)
Remarks
AC-2
414
16,265
Reference: U02-4%PuO2
AC-3
490
16,000
Controlled porosity:
U02-4%PuO2
AC-4
2000
Design variable: Annular, LTS, Higher grain size, Gap etc.
Metallurgical Hot Cell Facility at BARC
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

12. Burnup-15000MWd/tHE, LHR-404 W/cm Burnup-2000MWd/tHE, LHR-490 W/cm
U-Pu MOX Fuel
AC-2 cluster
PIE results  Indicative of normal performance of a fuel  Introduction of MOX fuel in TAPS BWR
β-γ autoradiograph
Equiaxed grains
Central dark porous region
Cs- depletion region
Burnup-15000MWd/tHE, LHR-404 W/cm
Higher C in the pellets (within specs) CO formation in sintering (LTS)  CO trapped in pores released during irradiation  reduced thermal conductivity of helium rise in the fuel central temperature and consequent restructuring.
AC-4 cluster
α-autoradiograph
Columnar grains
Pu- segregation
Burnup-2000MWd/tHE, LHR-490 W/cm
Central Void
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

13. ADVANCED FUEL FABRICATION FACILITY
PIE inputs
PIE results on U-Pu MOX Fuel pins with burn up to 16,000 MWd/tU was useful for type testing of MOX fuel and led to alternate fuel development program for TAPS
ADVANCED FUEL FABRICATION FACILITY
CIVIL CONSTRUCTION COMPLETED
1987
INTRODUCTION OF UO2
1989
INTRODUCTION OF PuO2
Oct 30, 1992
FABRICATION OF FIRST BWR MOX PIN
Dec 14, 1993
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

14. MOX Fuel Design for TAPS
Island design
1. Compatibility and complete interchangeability with UO2 fuel
2. Almost same operational and safety behaviour
All Pu design
Minimum number of MOX assemblies
Minimum types of fuel rods in a assembly
Island design
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019
All Pu design

15. MOX Fuel Design adopted for TAPS
“All Plutonium” design has been adopted to minimize the requirement of the number of MOX assemblies
Features
Same hardware as standard LEU assembly.
Water rod as spacer capture rod.
No Gadolinia rods .
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

16. Fabrication of Mixed Oxide Fuel in India
Process
Conventional PM route which involves-
Co-milling,
Precompaction/Granulation,
Compaction,
Sintering,
Pellet cleaning,
Loading of pellets in clad tubes,
TIG end plug welding for fuel element manufacture.
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

17. Important Steps of Fuel Fabrication By PM Route
Encapsulation of pellets
Cold compaction
Sintering
Sintered pellet
Mixing of powders
Quality control Checks
Dewaxing
Attritor
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

18. Final compaction Hydraulic Press
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

19. Ceramic Furnace for MOX Fuel Sintering
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

20. TIG Welding Chamber inside glove box
Fuel pin
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

21. PROCESS / Q.C. STEPS Physical Quality Control Chemical Quality Control
Density, Inspection
α- Autoradiography
He leak test, X-Radiography,
γ-scanning, Metrology, Visual
Chemical Quality Control
NWCC
Pu, Am, Isotopes
H, O/M, F, Cl, Metallic Impurities
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

22. PuO2 % in MOX PELLETS NWCC Vs CHEMICAL ANALYSIS
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

23. Gamma scan of BWR MOX pins
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

24. 12 Assemblies Fabricated and loaded in TAPS 1 & 2 during 90s.
Item
BWR
Enrichment
0.9,1.55,3.25
Pellet Dia (mm)
12.24 x 20
Zircaloy Tube OD (mm)
14.28
Wall thickness (mm)
0.89
Length of fuel element (mm)
3885
Fuel clad gap (micron)
Pellets per tube
200
Wt. of pellets per tube(g)
Tubes per bundle 36
BWR Fuel assembly
12 Assemblies Fabricated and loaded in TAPS 1 & 2 during 90s.
Peak burnup of ~ 20 GWd/t achieved.
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

25. MOX Irradiation Experience at TAPS
Assembly No.
Burn up MWD/T
Reactors
MB-726
MB-727
MB-870
MB-871
MB-877
MX-006
MX-7
MX-8
MX-9
MX-11
MX-12
15,825
16,085
15,527
16,454
14,925
16,335
19,080
18,200
11,399
8,500
9,300
TAPS-1
TAPS-2
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

26. Successful fabrication and irradiation of MOX fuel was carried out.
Conclusions
Successful fabrication and irradiation of MOX fuel was carried out.
MOX fuel fabrication technology has been established which can be used for fuel fabrication for light water reactors.
Use of MOX fuel in light water reactors will reduce the load on front and back end of fuel cycle.
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019

27. Thank you
Future of light water Tehcnology in INDIA (NC-FLWR19), Nov.2019