Chellapandi (PDF Download)

Special Manufacturing Processes in
Nuclear Industries
Dr.Baldev Raj, President, INAE
P Chellapandi, IGCAR, Kalpakkam
IGSCTC Workshop on
“Strategies and Concepts of Advanced Manufacturing”
Jan 23-24, 2014, New Delhi
Specific Features of Nuclear Industries
• Nuclear power plants: high capital cost intensive projects
• Special Materials and High material cost
• Manufacturing cost: 3-10 times the basic material cost due
to stringent manufacturing tolerances specified for meeting
the requirements on reliability & structural integrity
• Longer construction time: 5-10 years
• Essential to minimize capital cost of the reactor structures,
systems & components to achieve cost competitiveness:
lesser materials, shorter manufacturing and erection time
• Application of advanced manufacturing techniques and
high power computers and computer tools is an effective
mechanism for achieving the manufacturing with stringent
tolerances with challenging time schedule
500 MWe Capacity Sodium Fast Reactor
ASS ~ 3000 t; Alloy Steel ~ 500 t,
CS ~ 1000 t; struct. steel ~ 4,06,000 t
Lead ~ 320 t ;Concrete ~ 5,02,000 t
Sodium 1750 t
Structural Materials for Clad
Clad and Wrapper
High Void Swelling Resistance, Low Irradiation Creep and Improved High
Temperature Properties
Development of materials for achieving high burn-ups (~ 2,00,000 MWd/t)
Clad : Development of improved version of D9 (D9I) by optimisation of minor
alloying elements; Si, Ti and P (better void swelling resistance)
Wrapper : Optimized mod.9Cr-1Mo steel with controlled residuals to improve
ductile to brittle transition temperature
Alloy D9
Fuel Pins after Irradiation
Alloy HT9
B.J. Makenas et. al, 1990
Unique Features of SFR Components
• Sodium, high temperature, high neutron, long life (40-60 y)
• Large diameter thin walled shell & slender structures with stringent
tolerances pose challenges in manufacturing, handling & erection
• In-service inspection is difficult: Reliable pre-service inspection
• Residual stresses should be minimum: robust heat treatment
strategies
• Minimum number of materials to be used from reliability point of
view (but not preferred from economic considerations)
• Mainly austenitic stainless steels calling for careful considerations
for welding without significant weld repairs and distortions
• NSSS system components decide the project time schedule
• Leak tightness is very important in view of resulting sodium leaks
• Limited experience on manufacturing and erection of components
• Design and manufacturing codes still evolving
Achieving Tight Form Tolerances for Large Dia. Thin Shells
Challenges in Manufacture and Integration of Thermal
Insulation Panels on Safety Vessel
temperature(C )
Arrangement of thin polished sheets
Seismic qualification
185
165
145
125
105
85
65
45
25
0.00
0.02
0.04
emissivity
0.06
Confirmation of emissivity achieved
0.08
Manufacturing Challenges of Grid Plate
Austenitic stainless steel SS 316 LN
1758 sleeves / 4 nozzles / 1016 studs/ weight = 76 t
Bolted construction
Challenges in assembly
Hard facing of large diameter track with Colomonoy
Direction: Welded construction with minimum number of sleeves
Hard Facing Technology
• Stainless steel parts in contact with sodium have tendency
for self welding under little contact pressure. Hence, the
parts immersed in sodium undergoing relative movements
during various reactor operating conditions, are to be
critically examined to avoid self welding.
• The contact surfaces of these parts are generally deposited
with suitable materials with high hardness.
• Though cobalt-base alloys are the first choice for high
temperature hard facing applications, due to considerations
of induced radioactivity from Co60 isotopes, nickel-base
alloys have been chosen for hard facing.
• Hard facing without repair is the current challenge.
Hard Facing in Grid Plate
45
Proposed design
Hard Facing in Bottom Plate
Hard face (Colomony – 5) tracks to facilitate relative
movement between GP and CSS during thermal transients.
Base
Metal
Hard
facing
Improved design
During technology development, difficulty was faced in
achieving sound crack free deposit. Repair of cracks
resulted appearance of fresh ones.
Elaborate mockup trials varying deposit speed, current
characteristics at start and end of a given pass, No. of
passes
Critical review of the dimensions of deposit, groove design
and sequence of deposition.
HEAT TREATMENT :
Stress Relieving 750ºC
In-depth study on stress field in the vicinity of hard face and
its wear characteristics resulted in improved groove design.
Welded Grid Plate Concept for Future SFRs
SS 316LN and Weight = 33 t
909 Sleeves / 734 Spikes / 8 Nozzles / No fasteners
No need of hard facing (minimum differential thermal expansion)
Can accommodate more number of primary pipes
Challenges in Manufacturing of Roof Slab
Ø12840
31500
30000
Ø1900
Ø6210
LAMELLAR
TEARING
Ø2220
LAMELLAR TEARING AT ‘T’ & ‘L’ JOINT
(Despite UT on Plates & Control on ‘S <0.012’ & ‘P <
0.035’
PCD 9760
Ø12900
WELD
OVERL
AY
MATERIAL : A48 P2
ALTERNATE JOINT DESIGNS FOR
AVOIDING LAMELLAR TEARING AT ‘T’ &
‘L’ JOINT
Large box type structure with many penetrations - Fabrication of box
type structure is a very complex, time consuming and difficulty to
handle lamellar tearing problems and to meet dimensional
requirements due to its large dimensions
Direction: Elimination of box type concept
Teflon Coating on Large Diameter Shells
• ~ 6 m dia, total coating area ~ 3.15 m2
• Teflon coating technology was
developed with spray coating and
oven baking process on a 2 m dia
model Bearing Support Ring
Large Rotatable Plug
(LRP) of PFBR
• Teflon coating thickness - 50 µm The required coating thickness was
achieved with one primer coating and
three top coats of Teflon
• Distortion of the shells to be avoided
-The shell did not distort after 5
cycles of heating up to ~ 400 oC
followed by cooling in furnace (~ 24
Hours per cycle)
Model Bearing Support Ring of 2m dia after
Teflon coating (with test coupons)
M/s AMI Polymers, Ankleswar
Manufacturing Challenges of Steam Generator
Critical component since sodium and water
(which can undergo violent chemical reaction
generating high temperature, pressure and
hydrogen) coexists
~550 nos. of 23 long tubes to be welded with
thick tube sheets on either sides with in-bore
welding technique.
Reliability requirement is very high since, this
component decides the plant load factor
Material: G91 ferritic steel (mod. 9 Cr-1Mo)
Typical Welds In Fuel Pin and Wrapper
FUEL PIN END PLUG
(OD 6.6mm)
316 LN
HEXGANAL SHEATH
(131.3 WAF OUTER,
3.2 mm THK.)
20% CW D9
UNDER CUT
TIG WELD
(w/o FILLER)
TIG WELD
V-GROOVE
2° TAPPER ON
END PLUG
CLAD
(6.6 OD, 0.45mm THK.)
20% CW D9
FUEL PIN SUPPORT
COMPONENT
316 LN
RADIOGRAPHY :
Sensitivity better than 2% using
wire type Penetrameter
LEAK TEST :
Total leakage ≤ 10-15 Mpa m3/s
• One Repair Admissible Based on
Creep Tests
HEXCAN WELD :
LPE & RT / UT
• 80,000 welds per core
FUEL PIN
FUEL SUBSUB-ASSEMBLY
Manufacturing Processes of Control Plug
Upper part
Small rotatable plug
Middle part
Lower part
Benefits of Manufacturing Technology Development
Establishing
Machining Capabilities
Hard facing
Techniques
Heat treatment
Methodologies
Manufacture of
Large size dies
Welding & Inspection
Procedures
Development of Tooling
Manufacturing
Technology
Development
Manufacturing Methodology
for Large Sized Components
Sensitization of
Indian Industries
Assembly Procedures
Reduce Manufacturing Time
Review of Manufacturing
Requirements
Computer Application for Manufacturing & Erection
of Reactor Assembly Components
Step-3
Step-1
Transportation
Mounted on inner
wall
Placing of pads and
construction of upper
lateral portion of outer wall
Safety Vessel Erection
Transportation
Mounting on pads
Transmitting the loads to
outer wall through tie
rods
Step-2
Erection of Main Vessel along with Core Catcher & Grid Plate
Mounting of grid
plate and inner vessel
Mounting of top shield
Erection of Grid Plate, Inner Vessel & Top shield
Alignment and fit up of
main vessel and top
shield shell
Step-4
Final assembled view
Welding of Main Vessel with Top shield
3D Visualisation: Piping Layout
Application of Computer & Virtual Reality
PFBR Operator Training Simulator
A well trained operator is an asset for any Nuclear Power Plant.
• To impart comprehensive training to the
operators before commissioning of actual Plant.
• To Conduct transient tests that are not
practically possible in the real plant.
PFBR Simulated Flow Sheet
PFBR Simulator Development
Platform
• All the sub systems viz. Neutronics, Heat
Transport System, Steam Water System,
Electrical System, Fuel Handling System etc.
are modeled and integrated.
• The bench mark transients and malfunctions
have been modeled.
• The integrated system has been implemented in
PFBR simulator
• Training is being provided for the PFBR
operators
Erection of Large Dimensioned Vessels
Safety vessel into reactor vault
Grid plate into main vessel
Main vessel into safety vessel
Thermal baffle into main vessel
Inner vessel into main vessel
Roof slab on the main vessel
Robust Inspection Technologies for ISI of SFR Components
Load Cell
UT Module
Middle Wheel Steering
Mechanism
ISI Camera
Temperature
Sensor
Support Frame
Front Wheel
Assembly
ISI of MV and SV including CSS Shell Weld
Main vessel vibration monitoring through MEMS based Sensors
Industries involved in PFBR RA Construction
Sl.no
Components
Industries
1
Core Subassemblies
NFC, Hydrabad & L&T Hazira
2
CSRDM & DSRDM
MTAR, Hydrabad
3
Safety Vessel
L&T (SAS with KRR petals)
4
Main vessel
L&T (SAS with KRR petals)
5
Thermal Baffles inc. cooling pipe BHEL, Trichy
6
Inner Vessel
BHEL, Trichy
7
Core Catcher
WIL, Walchandnagar
8
Core Support Structure
WIL,Walchandnagar
9
Grid Plate
MTAR (Hardfacing by OMPLAS)
10
Primary Pipe
L&T Powai
11
Roof slab
L&T Hazira
12
LRP & SRP
Godrej
13
Control plug
MTAR, Hyderabad
Integrated Manufacture and Erection of RA
• Reactor Assembly and Civil Construction of reactor vault along with safety
vessel are constructed in parallel in matching time schedule so that
Reactor Assembly will be erected without any time delay
• Subsequently other reactor internals (kept ready) will be introduced
• Completion time for Reactor Assembly: ~5 y for PFBR & ~ 3 y for future FBRs
(Construction time reduction yields ~ 4% reduction in UEC)
• Scheme arrived at jointly in consultation with Industries
Computational Intelligence Based
Welding System
Digital Welding
Power Source
IR Camera
Welding Torch
Base Metal
Weld Metal
Thermal Images of Weld
Diffused arc in
Normal-TIG
Image Processing
& Neuro-fuzzy
based Control
System
Comparison between temperature Line scan profile and its first
Measurements of thermocouple
derivative plot for bead width
and IR camera
estimation
Constricted arc
in PEAF-TIG
12
mm
Weld bead shape
in Normal TIG
Isotherm of weld pool
in TIG welding
Weld bead shape
in PEAF-TIG
ANN Based Approach for
Estimating Bead Width &
Penetration Depth using IR
Thermal image of weld pool,
with on-line feedback control
Advanced Manufacturing for Future Reactors
• Additive Manufacturing
A technology leap from current manufacturing approaches by offering
more efficient methods of forming metal and other materials into
highly complex shapes and parts. Application to large size metallic
components needs further R&D
• Hydro-forming
Experimental and theoretical investigations towards limiting the
strains to produce defect free components.
• Ultra-high strain rate deformation of materials
Precise and accurate control of process parameters is challenging
• Magnetic Resonance Pulse Welding
Welding of Oxide Strengthened Steel (ODS) fuel clad tubes with end
cap
Summary
• Nuclear power plants provide high impetus for the
development of advanced manufacturing processes
• Nuclear industry offers several spin-off allied science and
technologies relevant to other high tech areas
• Application of high computing starting from material
modeling, simulation, design opimisation, design
confirmation, safety assessment, preparation of engineering
drawing, manufacturing, erection, operation, in-service
inspection and decommissioning sequences is the key for
realization of complete potential of nuclear energy
• Collaborative efforts among academic institutions, R&D
establishments and Industries are essential
Design, construction and operation of virtual power plant that can be used
by designers, regulators, industries and academicians, could be a good start
Thank You

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