A.Ravisankar,
V.Vijayakumar, B.M.Ananda Rao, U.Kamachi Mudali,
V.Sundararaman, R.Natarajan
An Indian Perspective of the Development of
Fast Reactor Fuel Reprocessing Technology
Reprocessing Group
Indira Gandhi Centre for Atomic Research
Kalpakkam-603 102
Pilot plant (CORAL)
Process flowsheet and
equipment evaluation
Demonstration Plant (DFRP):
FBTR fuel : 100 kg/y
(or)
PFBR fuel : 500 kg/y
Prototype plant (FRP):
PFBR Fuel : 7.5 t/y
PFBR Blanket : 6.5 t/y
FBTR CORAL
DFRP
PFBR FRP
2003
2014
2015
2016
2017
HEF
2015
Challenges associated with FBTR fuel reprocessing and
Strategies for solving them
Short cooling
Degradation of Solvent
High Pu content
Dissolution
Third phase formation
Criticality
-activity containment
Nature of fuel
Pyphoricity
Soluble organics interference
Development of short
residence time extractors
Development of
dissolution process
Solvent extraction
modeling
Design of cells with -tight requirement
Chopper development
Development of new
dissolution process
Challenges
High burn up & short cooled fuel
High Pu content-alpha tightness requirement
High acidic environment
Demand for robust Remote operation & maintenance
Design Aspects of Hot Cells
Limitations of the remote handling equipments, viewing systems and Radiation
hardened electronics
Equipment layouts
Equipments have to be developed with
Modular construction
Amenable for replacement/maintenance
Validate in the mock up facility
Spent
Fuel
Pu purification
cycles
Dissolution Feed
clarification
Co-extraction cycle
Chopping
U-Pu Partition
cycle
Off gas
treatment
Feed
preparation
Conversion to
Pu oxide Conversion to
Uranium oxide
Liquid
Waste
Liquid Waste
Gaseous effluent
Pu oxide U oxide
Sub Assembly
Dismantling Fuel Pin
Evaporation
Evaporation
Liquid Waste
Insolubles
U Purification
cycles
Hulls
Solvent
Cleanup
Raffinate
recovery
CORAL is in operation since 2003
Many reprocessing campaigns of FBTR spent
mixed carbide fuel with 70% Pu and burnup upto
155 GWd/t have been successfully completed
The material has been refabricated and loaded
back into the reactor
Operating Experience in CORAL
Vital inputs from CORAL operations…..
Process Flowsheet
Process Equipment design; operation and
maintenance
Hot cell equipment and systems design
PROCESS FLOW SHEET RELATED TECHNOLOGY DEVELOPMENT
Item Technology Status
Process flowsheet Process flowsheet demonstrated
Dissolution
Dissolution of Plutonium rich mixed
carbide fuel is more complex than the
moderately Pu rich MOX fuels of
PFBR
Co-extraction Demonstrated in CORAL
Partitioning
Aqueous phase partitioning flowsheet
being demonstrated; Organic phase
stripping using uranous demonstrated
in simulated experiments
Pu purification
Three decades of thermal reactor fuel
reprocessing experience is deployed for
fast reactor fuel reprocessing also
Uranium purification
Pu reconversion
Uranium reconversion
VALIDATION OF PURIFICATION FLOWSHEET
1357911131517192010
-4
10-2
100
102
Stage No.
Pu
(IV
) [
g/L
]
Aq. (Exp.)
Aq. (Pred.)
Org. (Exp.)
Org. (Pred.)
1357911131517192010
-2
10-1
100
101
102
Stage No.U
(VI)
[g
/L]
Aq. (Exp.)
Aq. (Pred.)
Org. (Exp.)
Org. (Pred.)
1357911131517192010
-4
10-3
10-2
10-1
100
101
Stage No.
Ru
(III
) [
g/L
]
Aq. (Exp.)
Aq. (Pred.)
Org. (Exp.)
Org. (Pred.)
1357911131517192010
-2
10-1
100
Stage No.
Zr(
IV)
[g
/L]
Aq. (Exp.)
Aq. (Pred.)
Org. (Exp.)
Org. (Pred.)
The stage concentration profile could be predicted reasonably
accurately, it was found that the stage efficiencies of low
concentration stages are extremely low; this could be either due to
entrainment or due to improper mixing; If this is resolved less
number of stages would be sufficient;
The raffinate losses of plutonium could not be brought down below
approx 10 mg/l; this could be because of very low efficiency in such
low concentrations or due to the presence of in-extractable plutonium
species present in aqueous phase
The experiment has been done with the fission products (Zr, Ru)
separately; The contamination of ruthenium in the product is < 0.01
mg/g of (U+Pu); of zirconium is <0.2 mg/g of (U+Pu); The
decontamination would be better in the actual process since organic
loading would salt out these fission products
135791113151719200
10
20
30
40
50
60
70
80
90
Stage No.
Pu
(IV
) org
. [g
/L]
1
2
3
4
5
6
7
8
9
10
SENSITIVITY ANALYSIS – THIRD PHASE FORMATION
Sl.
No Condition
Organic
flow
Scrub 1
flow
Scrub 2
flow
1 Normal 1.1 0.3 0.7
2 Reduced org 1 0.3 0.7
3 Increased org 1.2 0.3 0.7
4 Increased scrub 1 1.1 0.4 0.7
5 Increased scrub 2 1.1 0.3 0.8
6 Reduced org and
increased scrub 1 1 0.4 0.7
7 Reduced org and
Increased scrub 2 1 0.3 0.8
8 Reduced org 0.9 0.3 0.7
9 Decreased scrub 1 1.1 0.2 0.7
10 Decreased scrub 2 1.1 0.3 0.6 To avoid third phase formation
A/O should not vary >10%;
S1/A or S2/A should not vary > 10%
Reductant 3
Flow: 2ml/min
U(IV):~ 3.9 g/L
U(VI): <0.4 g/L
HNO3 : 0.47 M
N2H4 : 0.5M
Reductant 2
Flow: 2ml/min
U(IV):~ 33.9 g/L
U(VI): <3 g/L
HNO3: 0.67 M
N2H4 : 0.5 M
Aq. Product
U : 0.7 g/L
Pu(III): 23.5 g/L
HNO3: 1M
Vol : 3.3L
Lean Organic
U(VI): ~ 37.0 g/L
U(IV): BDL
HNO3: 0.25 :Vol:6.8L
Org. Feed
Flow : 6.6ml/min
U(VI) : 52.43 g/L
Pu(IV) : 21.42 g/L
HNO3: 0.74 M : V:3.7L
Reductant1
Flow: 2ml/min
U(IV): 33.9 g/L
U(VI): <3 g/L
HNO3: 0.67 M
N2H4 : 0.5 M
Organic scrub
Flow : 6ml/min
[TBP]: 30 vol %
HNO3 : ~0.06 M
Uranium and Plutonium Partitioning flow sheet
1357911131517192010
-4
10-3
10-2
10-1
100
101
102
Stage No.
Pu
(to
tal)
[g
/L]
Aq. (Exp.)
Aq. (Pred.)
Org. (Exp.)
Org.(Pred)
510152010
-2
10-1
100
101
102
103
Stage No.
U(t
ota
l)
[g/L
]
Org. (Exp.)
Org. (Pred.)
Aq. (Exp.)
Aq. (Pred.)
R&D on optimising the process flowsheet with
a view to reduce the number of SX cycles
Solvent clean up process using hydrazine carbonate has been
developed for treating the lean organic for recycle. This could remove
the plutonium retained by DBP apart from removing the degradation
products without forming crud. This process is undergoing
continuous improvement to reduce the secondary wastes.
Reduction of solvent waste volume
Solvent purification from degradation products:
Vacuum distillation with a falling film evaporator.
Item Status
Fuel handling
cask
Experience exists on both the subassembly handling and pin
handling in cask; Improved designs for higher throughputs
have been made;
SA dismantling Experience exists for FBTR SA dismantling in PIE cells of
IGCAR
Chopper
CORAL Experience
Dissolver
Centrifugal
clarifiers Experience available in CORAL
Centrifugal
extractors Robust design has got evolved during CORAL campaigns
Pulse columns Three decades of thermal reactor fuel reprocessing experience
is adequate for fast reactor fuel reprocessing plants Evaporators
Equipment development
Y -AXIS
Z -AXIS
X -CARRIAGE
TOOL
HOLDER
DUMMY
HEXCAN
INDEXING
HOLDER
?
Proposed Location for
Dismantling machine
Fig.1. Lay out of HEF Hot cells
Fig.6. Schematic of Motion Control SystemFig.5. Scheme and Major Dimensions of the Mechanical System
Fig.4. Subassembly Dismantling Machine in HEF Hot Cell no.2
Fig.7. Retreival of Fuel Bundle from Hexcan
Fig.3. PFBR Subassembly showing cut locations
FIRST CUT
(circumferential)
SECOND CUT
(circumferential)
THIRD CUT
(longitudinal)
Fig.2. FBTR Subassembly showing cut locations
FIRST CUT
(circumferential)
SECOND CUT
(circumferential)
THIRD CUT
(longitudinal)
Cross-section of
subassembly
Star styli
Touch probe
Fig.8. Method of taking Surface Points from the Faces of a clamped
Subassembly using Touch Trigger Sensor during Profilometry
Input from linear displacement scales
POWER
SUPPLY
X,Y,Z
DRIVE
UNIT
DRO
PCX,Y,Z
CONTROL
UNIT
MI 8
PROBE
INTERFACE
to stepper
motors
XYZ Translation Stage
Y
Z
Shielding glass window
Back
door
access
STAND ALONE
STEPPING MOTOR
CONTROLLER
(5-axis)
IBM - PC
PENDANT
Stepping
Motor Drive-I
X1-Motor
Stepping
Motor Drive-II
Stepping
Motor Drive-III
Stepping
Motor Drive-IV
Stepping
Motor Drive-V
X2-Motor
Y -Motor
Z -Motor
SA holder
motor
RS485/RS232
CAN/USB/RS232
Schematic of Motion Control System
Linear
displacement
scale
Motion I/O
Eddy current
signal encoder
o/p converter
2nd CUT 3rd CUT
1st CUT
?
Proposed Location for
Dismantling machine
Fig.1. Lay out of HEF Hot cells
Fig.6. Schematic of Motion Control SystemFig.5. Scheme and Major Dimensions of the Mechanical System
Fig.4. Subassembly Dismantling Machine in HEF Hot Cell no.2
Fig.7. Retreival of Fuel Bundle from Hexcan
Fig.3. PFBR Subassembly showing cut locations
FIRST CUT
(circumferential)
SECOND CUT
(circumferential)
THIRD CUT
(longitudinal)
Fig.2. FBTR Subassembly showing cut locations
FIRST CUT
(circumferential)
SECOND CUT
(circumferential)
THIRD CUT
(longitudinal)
Cross-section of
subassembly
Star styli
Touch probe
Fig.8. Method of taking Surface Points from the Faces of a clamped
Subassembly using Touch Trigger Sensor during Profilometry
Input from linear displacement scales
POWER
SUPPLY
X,Y,Z
DRIVE
UNIT
DRO
PCX,Y,Z
CONTROL
UNIT
MI 8
PROBE
INTERFACE
to stepper
motors
XYZ Translation Stage
Y
Z
Shielding glass window
Back
door
access
STAND ALONE
STEPPING MOTOR
CONTROLLER
(5-axis)
IBM - PC
PENDANT
Stepping
Motor Drive-I
X1-Motor
Stepping
Motor Drive-II
Stepping
Motor Drive-III
Stepping
Motor Drive-IV
Stepping
Motor Drive-V
X2-Motor
Y -Motor
Z -Motor
SA holder
motor
RS485/RS232
CAN/USB/RS232
Schematic of Motion Control System
Linear
displacement
scale
Motion I/O
Eddy current
signal encoder
o/p converter
1st CUT
2ND CUT
3RD CUT
PULSED Nd-YAG LASER SYSTEM Laser power 150 watts (av.)
Maximum pulse energy 50J
Laser spot Dia 0.4mm
Nitrogen as purge gas
Laser Torch
Cut Location
Fuel Pin Bundle
Batch size: 10 pins
Controller
PC compatible with
MMI interactive
Chopping of 155GWd/t at CORAL
CUT CYLINDER REPLACEMENT
CUTTING TOOL REPLACEMENT
STEPPER MOTOR REPLACEMENT
CHOPPER LID OPENING
Maintenance of Chopper in CORAL
CHALLENGES
SPACER WIRE ENTANGLEMENT
CUTTING TOOL FAILURE
DRIVE FAILURE
Ten pins will be cut with a cutting force – 3 Te and push by single pusher.
Multiple cutting profile tool adopted to meet the chopping capacity
requirement
Length of fuel pin : 2580mm push rod is approx 350mm.
The push and pull mechanism developed to reduce the size of the cell
Challenges Modifications
Entanglement of spacer wire Modified the gripper, stationary and cutting tool
Anticipated Trouble in Rotation of magazine by ratchet
arrangement
Improvement using LM Slider
Retention of chopped pins, in the dissolver chute
Increasing the inclination of the chute connecting chopper &dissolver
Replacement required for the shunter
Made in modular construction
Designed for chopping Mark – I fuel Designed for in chopping 3different dimensions of pins (i.e., carbide Mark 1,
Mark 2 and oxide fuel pin)
Linear slide for Magazine movement.
Modified gripper and cutter.
Chute – 70 slope
Multi pin Chopper-FRP
Single pin Chopper-DFRP
Challenges in the future designs of Chopper
ELECTRODE
REPLACEMENT
REMOTE MAINTENANCE OF DISSOLVER IN CORAL
HULL TRANSFER
Mock-up Dissolver vessel
with inspection device
Sparger pipe
Internal Surface of the chute & Port
Position sensitive device for triangulation (~ 15 microns) for non-
contact inspection of reprocessing vessel - 11.5 N HNO3 at high temperature (1150 C)
PSD
Scanned Image of the weld
Titanium Mock-up dissolver hot limb
A
B
C
Thickness profile of the vessel along the markings A, B and C marked on the vessel
Thickness Range 6.02-6.08 mm A
B C
REMOTE INSPECTION OF THE DISSOLVER VESSEL IN CORAL
dissolver vessel
DESIGN CHALLENGES IN DISSOLVER
CONCEPTUAL VIEW OF
DISSOLVER AND ELECTROLYZER
Material of Construction
SS corrosion rate [~1500 mpy]
Titanium Grade-2
High Corrosion resistance [~5 mpy]
Fabrication expertise including dissimilar joint
available. Filler Wire
A special alloy Ti-5%Ta-1.8%Nb filler wire
Chopper Chute
Junction Annular Limb
Bottom Block
DFRP-FBTR Dissolver
Fuel Charging Limb
Bottom Block Basket
Hull agitation is incorporated to reduce the Pu loss in
hull
CORAL Dissolver
Mock-up Machining of Critical Components
Mock-up Dissolver
Vessel with Z-Axis
assembly on the top of
the vessel
Assembly of the
3-Axis Scanner
►Device has been made and tested for all motions
Inspection head of the
3-Axis Scanner
3-Axis Scanner for ISI of DFRP Dissolver
FEED CLARIFICATION CENTRIFUGES
Speed Range: 15000 to 40000 rpm
Nominal opg speed: 20000 rpm
Nominal centrifugal force: 11250 g
Bowl inside dia: 50 mm
Bowl inside length: 250 mm
Bowl capacity: 350 cc
Drive: AIR TURBINE
DESIGN CONSIDERATION
Nuclear criticality
Containment
Remote operability & maintenance
Unbalance forces
The overall size of the rotating bowl is approximately 58 mm dia & 500mm length.
It consists of 28 precisely machined components with different materials.
Concentricity and runout maintained less than 20 microns.
Dynamic balancing was achieved within G1.0 grade.
CHALLENGES..
S.No Challenges
encountered
Causes Solutions
1
Vibrations Unbalance in the bowl. Balance to G1.0 grade as per ISO 1940.
Misalignment of
connecting shaft &
Bend in the shaft.
Sequence of fabrication and inspection stages shall be strictly
followed in order to achieve desired dimensional tolerances.
The material of construction for shaft is AISI 410 grade.
2 Loosening of
retainer ring
Effect of vibration. Increase the interference between retainer ring and bowl.
Preventive maintenance.
3
Frequent bearing failure High Acidic environment Bearing Material changed to Alacrite-554 (Cobalt based super
alloy Cr, W) (Excellent resistance to abrasion and nitric
acid)
Dynamic Modal Analysis
Mode Frequency (Hz) Critical speed ( RPM)
1 28.04 1682
2 35.04 2103
3 35.38 2123
19 251.19 15071
26 374.34 22460
Rapid transition of rotating bowl through critical
speed is necessary.
Among the different modes, bending mode is most
damaging as far as the critical speed is considered.
Operating speed changed from
15000 to 18000 rpm to
maintain 20% margin with critical speed.
CENTRIFUGAL EXTRACTORS
Nominal throughput: 10 lit /hr
Operating speed: 3500 rpm
Average centrifugal force: 200 g
Residence time/stage: 5-10 sec
• Compact design
• Amenable for Remote
operation and maintenance
• Low residence time
• High capacities
Aq in Org in
Org out
Aq out
Maintenance of Centrifugal Extractors in CORAL
CE Dismantling
Equipment
SAMPLE HANDLING ROBOT Capping and Decapping
Robot Pippetting Robot
Sampling systems in CORAL
Sampling system Capping and Decapping system
Sampling systems in DFRP
Hull monitoring system using gamma spectrometry
DFRP Dissolver cell
Hull basket cavity Specification:
Cap : 250 kg
LT : 1850 mm
CT : 7950 mm
HT : 5350 mm
Speed : 0.5 m/min
Ce144- 2191 Kev
Mn54- 834 Kev
Co60
1173 Kev 1332 Kev
Important achievements in the
Auxiliary systems development
Incell crane for DFRP
Pu assaying in solid wastes - Passive Neutron
Minimum Detection Limit is 35 mg Pu per
Drum
Specifications:
Cap : 50 KgLT : 1000 mmCT : 10000mmHT : 1000mmSpeed : 0.5 m/min
MAIN
GIRDER
LT DRIVE &
SPROCKET
DRIVES & LIMIT
SWITCHES
Incell crane for CORAL
The ISI vehicle and the ISI camera image and user interface
Vehicle, ISI guide ways and remote handling tools developed in-house
Extensive mock-ups done to ensure failsafe operation
1St Campaign concluded successfully
Inspection of CORAL Waste Vault – With Remotely Operated Vehicle
ACQUIRED IMAGES REMOTE OPERATIONS WITH ISI VEHICLE
Mobile Robot for ISI of DFRP waste-vault tanks
MOBILE ROBOT
• Driving Wheel - 2 Nos
• Castor Wheel - 4 Nos
• Speed :
0 m/min - 2 m/min
• Examination- Camera
MANIPULATOR
• Reach of Manipulator- 750mm
• DOF - 5
• Payload – 5 kg ACQUIRED IMAGES
CORAL
DFRP
DFRP under construction
Fast Reactor Fuel Cycle Facility
CONCLUSION
The CORAL campaigns have demonstrated the deployability of PUREX process for Pu rich FBTR fuel, which enabled the design of DFRP and FRP to be taken up confidently.
The operation and maintenance experience vindicated the hot cell systems.
R&D issues have been taken up to improve the availability and capacity factors.
Also the thrust is on reducing the waste volumes and radiation expenditures.
