4 . . PROTOTYPE FAST BREEDER REACTOR

1 114 BARC HIGHLIGHTS REACTOR Technology & EngineeringPrototype fast BREEDER ReactorThe second stage of Indian nuclear power programme involves establishing fast BREEDER Reactors for power generation. The PROTOTYPE FastBreeder REACTOR is being developed to demonstrate the techno-economic viability of fast BREEDER REACTOR technology. This chapter highlightsthe recent activities carried out in the fields of radiation shielding and design of inclined fuel transfer 4 4 4 4 .. PROTOTYPE fast BREEDER REACTORINTRODUCTION115 REACTOR Technology & Engineering BARC HIGHLIGHTSP rototype fast BREEDER ReactorThe PFBR is a 500 MWe, sodium cooled, pool type, mixed oxide (MOX) fuelled REACTOR having two secondary loops. The primary objective ofthe PFBR is to demonstrate techno-economic viability of fast BREEDER reactors on an industrial scale.

2 The entire primary sodium circuit iscontained in a large diameter vessel ( 12900 mm) called main vessel and consists of core, primary pumps, intermediate heat exchanger andprimary pipe connecting the pumps and the grid plate. The vessel has no penetrations and is welded at the top to the roof slab. The main vesselis cooled by cold sodium to enhance its structural integrity. The core subassemblies are supported on the grid plate, which in turn is supportedon the core support HIGHLIGHTS REACTOR Technology & EngineeringPrototype fast BREEDER ReactorThe main vessel is surrounded by the safety vessel, closely following the shape of the main vessel, with a nominal gap of 300 mm to permitrobotic and ultrasonic inspection of the vessels. The safety vessel also helps to keep the sodium level above the inlet windows of the intermediateheat exchanger ensuring continued cooling of the core in case of a leak of main vessel.

3 The inter space between main & safety vessel is filled withinert nitrogen. The main vessel is closed at its top by a top shield, which includes roof slab, large & small rotary plugs and control plug. The topshield is a box structure made from special carbon steel plates and is filled with heavy density concrete (r = 3500 kg/m3) and provides thermaland biological shielding in the top axial direction. The principal material of construction is SS 316 LN for the vessels and boiler quality carbonsteel for top shield. The REACTOR vault concrete provides the biological shielding in the radial and bottom axial direction outside the main REACTOR Technology & Engineering BARC HIGHLIGHTSP rototype fast BREEDER AND DEVELOPMENT OF INCLINEDFUEL TRANSFER MACHINE (IFTM) FOR FUELHANDLING SYSTEM OF PFBR-500 MWeInclined Fuel Transfer better utilization of fuel & available natural resources in Indiaand based on the successful operation of 40 MWt fast BREEDER TestReactor (FBTR) at the IGCAR, Kalpakkam, a 500 MWe PrototypeFast BREEDER REACTOR (PFBR) is being built at Kalpakkam, which willbe first REACTOR of its kind in India.

4 PFBR will be a 500 MWe (1250 MWt), 2-loop, sodium cooled, pool type REACTOR . It will utilize theMoX fuel (PuO2 + UO2) and depleted Uranium oxide as is designed vertical in configuration. Off load refuelling isenvisaged for PFBR. It is designed to do refuelling after every 185 Effective Full Power Days (EFPD) of the REACTOR . In one refuellingcampaign 62 fuel SA, 25 blanket SA and 5 absorber SA will bereplaced. Inclined Fuel Transfer Machine (IFTM) is one of the fuelhandling machine of PFBR which transfers spent SA from reactorvessel to fuel building and fresh SA from fuel building to spent sub-assembly (SA) handling, IFTM receives the spentSA from Transfer Arm (TA) inside the REACTOR vessel and delivers it toCell Transfer Machine (CTM) in fuel building to transfer it to storagebay and during fresh SA handling it receives fresh SA from CTM anddelivers it to TA to place inside the REACTOR core.

5 IFTM transfers SAin 170 inclined position to the vertical. Design of IFTM is totallyindigenous. The irradiated SA after being cooled at storage locationinside REACTOR vessel is put in a sodium filled Transfer Pot (TP) of IFTMby Transfer Arm (TA) at In-vessel Transfer Position (IVTP). TP is thenhoisted up inside Rotatable Shielded Leg (RSL) by hoisting mechanismthrough Primary Ramp (PR) & Primary Tilting Mechanism (PTM). RSLis rotated by 1800 by rotation mechanism and aligned on secondaryside and the TP is lowered in Ex-Vessel Transfer Position (EVTP)through Secondary Ramp (SR) Secondary Tilting Mechanism (STM)from where the irradiated SA is replaced by fresh SA using CellTransfer Machine (CTM). The fresh SA will be transferred fromEVTP to IVTP in the reverse manner.

6 A shield plug has been providedin the primary ramp for attenuating primary sodium gamma raysduring REACTOR operation. Gate valves have been provided on bothprimary and secondary ramps, which act as a barrier between theradioactive argon cover gas of MV & fresh argon gas of Fuel TransferCell (FTC), which is required for containment isolation. Bellows areprovided on both sides to absorb the differential thermal handling takes place within a leaktight cell. Adequate shieldingand sealing arrangement has been provided in IFTM. During fuelhandling IFTM internals are maintained at high temperature (423-473 K) by hot argon flushing during fuel handling operation inorder to maintain sodium in liquid form filled in transfer pot. Alsoduring REACTOR some of the components of IFTM viz.

7 PR & PTM seevery high temperatures (823 K)..Design and analysisIFTM design has been finalized. Detailed design of all the componentsof IFTM has been completed. Design of all the components of IFTMis based on all the types of loadings viz. dead weight, thermalloading and seismic loading. Detailed stress analysis has beenperformed for static, thermal and seismic loadings. Design of PR& PTM has been analyzed for creep and fatigue loadings also as theysee high temperature and thermal cycling. Profile of rampsand tilting mechanism has been finalized by making3-D models and simulating the pot movement through118 BARC HIGHLIGHTS REACTOR Technology & EngineeringPrototype fast BREEDER Reactorthem, which was done using VIZ software. Various design documentsand reports (45) have been prepared and activitiesFunctioning of IFTM has been demonstrated by commissioning ofsmall scale (1:10) acrylic working model of IFTM.

8 Design of criticalcomponents has been validated by making small scale models ramp, tilting mechanism, siphoning arrangement, safetybrake, setup of double chain hoisting mechanism has beencommissioned to see the behavior of chain-sprocket system andchain sensing arrangement. Various functional and designrequirements viz. compatibility of chain & sprocket, possibility ofchain coming out of sprocket grooves, entanglement of two chainswhile pot movement, effect of unequal length of chains, behaviorof chain with load, performance of chain sensing arrangement,etc. have been checked. Load testing of operation and emergencyhandling have been demonstrated successfully. Endurance test is completion of detailed design various detailed drawings (165)and technical specification for manufacture of IFTM have beenprepared and handed over to BHAVINI to float the tender.

9 Bhavinihad floated tender for manufacture of IFTM and quotations werereceived. Technical evaluation of bidders is in testIn future it is planned to manufacture an IFTM and test it in shopfor functional requirements. Then IFTM will be installed at LargeComponent Test Rig (LCTR), Kalpakkam for performance test inreactor simulated conditions. First it will be tested in air at ambientconditions and then at REACTOR simulated conditions along withcontrol system before making it REACTOR setup of hoisting mechanismSomesh Rai REACTOR Technology & Engineering BARC HIGHLIGHTSP rototype fast BREEDER fast BREEDER REACTORSHIELDING EXPERIMENTS AT APSARAPFBR is a pool type sodium cooled fast REACTOR . Core is surroundedby fertile blankets and in-vessel shielding .

10 The Intermediate HeateXchanger (IHX) and sodium pumps are in the pool. The in-vesselshield is provided to reduce radiation damage to inner vessel,secondary sodium activation, activation of IHX, sodium pumps,axial leakages through bottom FP gas plenum. Mockup shieldingexperiments in Apsara shielding corner were carried out to optimizedesign of this in-vessel is a 1 MWth swimming pool REACTOR with HEU Al alloy fuel. Itis presently operated up to 400 kWth. As Apsara is a thermal REACTOR ,PFBR blanket leakage neutron spectrum in shielding corner wassimulated using depleted uranium fuel of experimental programmes Six radial bulk shielding experiments were planned to evaluatesecondary sodium activation. One axial bulk shielding experiment was planned to estimateattenuation of neutrons reaching neutron monitoringsystem (fission counters).