innovations in equipment erection of … in equipment erection of prototype fast breeder reactor...
Post on 10-Apr-2018
219 Views
Preview:
TRANSCRIPT
INNOVATIONS IN EQUIPMENT
ERECTION OF PROTOTYPE FAST
BREEDER REACTOR (PFBR)
S.Sreekanth, Prabhat Kumar
Bharatiya Nabhikiya Vidyut Nigam Limited (BHAVINI),
Department of Atomic Energy, INDIA
Email: skanth@bhavini.co.in
INTRODUCTION ON PFBR
• Type : Fast Breeder Reactor
• Fuel : PuO2 + UO2
• Reactor thermal Power: 1250 MWth
• Electrical output : 500 MWe
• Coolant : Sodium
• Gross thermal Efficiency: 40%
Reactor Vault (RV)
• The reactor assembly is housed in a concrete
vault lined with carbon steel called reactor vault.
• Tertiary containment for radioactive primary
sodium in Main Vessel in the highly unlikely
eventuality of leak in the both Main Vessel and
Safety Vessel.
• Reactor vault consists of Bottom Shield, Lower
lateral and Upper Lateral
• PFBR Equipment erection was a challenging task where
thin walled vessels had transported and handled with utmost
precautions to avoid redial forces on the vessels, which
could buckle the vessels.
• There was a real challenge in lifting the vessels without
swing, placement of large size and heavy vessel at a
distance of 57 meters where the crane operator has no line
of sight to equipment's being erected.
• Lot of care had been taken during lifting, handling and
erection of thin walled ODC with innovative methods used
for lifting fixtures, guiding arrangements, alignment fixtures
and achieved the stringent erection tolerances.
EQUIPMENT ERECTION OF PFBR
Details of Safety Vessel(SV)
• SV dimensions (OD) - Ø 13540 mm x
12800mm (height)
• SV with thermal insulation(OD) - Ø 13840 mm
• SV shell thickness - 15 mm to 20 mm
• Material of Construction - SS 304LN
• Weight - 155 MT
• SV support flange (OD) - Ø 14960 mm
• RV opening (ID) - Ø 14200 mm approx.
• On outer surface of SV, metallic insulation (0.1 mm thick sheet) of 150 mm thickness is provided.
• Handling of SV during the erection was a very challenging task , because SS insulation was a fragile sheet and impossible to repair any defects occur on the same.
Requirement of Load test before SV erection
• To handle such a huge ODC, there was a
requirement of conducting a load test to qualify
the lifting gear for handling of SV and validate
the SV erection procedure.
• Load test for base frame, rails and trolleys.
- Fabrication of test base frame of 16 m x 16 m
Innovations in safety vessel erection
• PFBR project is being constructed very proximity to sea
shore and to handle such huge vessel (SV), the following
mock up tests were conducted to validate the SV
erection procedure.
• Mock up test for estimating wind load acting on SV
during shifting towards RV.
• Mock up test for smooth passage of SV inside RV
Challenges faced during SV erection
• Lifting & handling of such a huge cylindrical shell and
maintaining the same horizontally at top.
• Safely lowered into RV without any damage on SV
thermal insulation and achieved erection tolerances as
per design requirements
Details of Main Vessel (MV)
• MV dimensions (OD) - Ø 12900 mm x
12940mm (height)
• MV shell thickness - 25 mm to 30 mm
• Material of Construction - SS 316LN
• MV Weight with CC, CSS, MVCP - 202 MT
• The primary sodium circuit is housed in a single
vessel called main vessel and it is very important
reactor component which supports the Core
Catcher, Core Support Structure, Thermal baffle ,
Grid Plate, Inner Vessel and active Core.
Main Vessel is being lowered and aligned through guiding mechanisms
Radial Guiding System
Angular Guiding System
Ring spider Arm
MV
Innovations in erecting Main Vessel
• 4 nos. of connecting rods were designed for MV load and
fabricated to achieve an uniform length, to avoid tilting of MV
during handling/erection.
• MV was lifted from below the centre of gravity point (CG) (i.e.
lifting points of MV are below CG point). To avoid toppling of
MV, 4 nos. of connecting rods were used for MV handling.
• The connection between lifting spider and component is a rigid
connection through the connecting rods. Since connecting rods
can take tensile and compressive loads.
• 4 nos. of lifting lugs have been welded on CSS such way that, it is
radially towards the centre of vessel to avoid dangling of MV
during handling of the same.
• Precise alignment of MV horizontality achieved by ring spider
arms and connecting rods.
Challenges faced during MV erection
• Lifting of main vessel was from below the CG point.
• Lifting of main vessel without swing and dangling.
• Lifting & handling of such a huge cylindrical shell and
maintaining the same horizontally at top.
• MV lowered safely into SV without any mechanical hindrance
within the small radial clearance between MV and RV.
• Precise alignment of MV with its internals to achieve
concentricity, axis orientation and horizontality.
Alignment requirements Target Achieved
GP Horizontality in MV mm) ±0.5 ± 0.45
GP vertical axis shift w.r.t. LRP support
flange (mm) Concentricity)
Within 3 1.32
Height between GP and LRP support
flange (mm)
11559 ± 1.5 mm 11557.5 to 11558
LRP flange horizontality (mm) ±1.0 ± 0.5
Details of Steam Generator (SG)
• Steam generator (SG) is a vertical, shell and tube type heat
exchanger and PFBR consists of 8 nos. of SGs.
• SG Material - 9Cr-1 Mo
• SG Overall dimensions - 26 m length xØ1500mm
• Weight of SG - 35MT
• Total nos. of tubes - 547
• Dimensions of each tube-17.2 mm x 2.3 mm wall thickness
• The main function of SG is to transfer the heat from
secondary sodium system to feed water there by generating
superheated steam.
INNOVATIONS IN SG ERECTION
• 26 meters length, 45 MT weight dummy Steam
generator structure was made exclusively for
conducting load test for transportation cum
vertical making structure.
• Mock up test was conducted with simulating the
actual SG handling conditions and validated SG
erection procedure.
Dummy SG fixing with SG support structure
SG vertical support structure
Transportation structure with dummy SG
Challenges faced during SG erection
• Making of Steam generator horizontal to vertical
position without dangling.
• Lifting of Steam generator alone in horizontal
condition due to non-uniform mass
top related