LEADER WP3: Conceptual Design Status L. Mansani

WP3 Tasks Task Reference plant configuration of a LFR (ANSALDO, CIRTEN, EA, JRC-IE, SRS) Task SG damping pressure waves system design (MERIVUS, CIRTEN, ENEA) Task Primary system conceptual design of the ETDR (SCKCEN, ANSALDO, EA, SRS) Task Secondary system conceptual design of the ETDR (EA, ANSALDO) Task DHR system conceptual design of the ETDR (ANSALDO, SCKCEN) Task Plant layout of the ETDR (EA, ANSALDO)

Task 3.1: ELFR Fuel Assembly blocked with Tungsten ballast, Lower and Top Core Plate

Task 3.1 ELFR: Inner Vessel, Core support and Fuel Assembly

ELSY The reference design of ELSY SG features a 22,22 mm OD tube, 3 mm thick with axial and radial pitch of 24 mm. The leaked peak water/steam flow rate calculated by Ansaldo is 15 kg/s for a cumulated amount of about 1 kg in the first tenth of second and 3,4 kg in the first second. (Ansaldo´s presentation at the ELSY meeting, Bologna, February 25, 2009). LIFUS The maximum achievable flow rate in LIFUS during the first tenth of second is estimated to be no more than 60% (9kg/s) of the reference water/steam flow rate. Proposal for LIFUS Guillotine tube rupture cross section proportional to the outlet flow rate (same speed) (12,6/16,22)^2÷0,6 Free cross section of the lead flow path around the six surrounding tubes proportional to outlet flow rate. Task SG damping pressure waves system design: Proposal of the next tests in LIFUS 5 2*2,59+1,3 ÷ 0,6*(4,61*2+1,78)

Task SG damping pressure waves system design: Test section design

 Physical behaviour of water blown into hot lead  Mechanical impact of the SGTR accident on the surrounding tubes  Performance of the perforated shells alone to ensure no overpressure outside the SG.  Performance of the passive device to deviate upward the flow rate (if necessary).  Pressure effects in the downcomer resulting from lead released at the primary system free level.  Exclusion of significant loads at core level (Partially available data) (Expected results from the next phase of LIFUS-5 tests) (Tests to be planned on larger test facilities) Task SG damping pressure waves system design: Expected information from the test campaign.

Task 3.3 ALFRED Reactor Block Configuration

Task 3.3 Reactor Vessel Inner Vessel radial support Support flange Cover flange The RV is a cylindrical vessel with a torospherical bottom head anchored to the reactor pit from the top The reactor vessel is closed by a roof that supports the core and all the primary components. The RV upper part is divided in two branches by a “Y” junction: the conical skirt that supports the whole weight and the cylindrical that supports the Reactor Cover. A cone frustum welded to the bottom head has the function of bottom radial restraint of Inner Vessel.

Task 3.3 Inner Vessel Upper grid Cylinder Lower grid Inner Vessel assembly Pin

Task 3.3 Steam Generator Vertical view Vertical section Horizontal section

Fuel Transfer System Concepts MYRRHA - ALFRED comparison © SCKCEN ComponentItemMYRRHAALFRED ReactorIn vessel storageYes In-vessel fuel storage no Cooling period420d (840d) (not fixed)10d (not fixed) FAGeometryHexagonal wrapper, wired fuel pin Hexagonal wrapper ReshufflingAt the bottom, by IVFH machineOn top Loading/unloadingTop loading FAFuel vector(U,Po)O2 MOX–35%Pu (U,Po)O2 MOX–30%Pu U,Po)O2 MOX–30%Pu (not fixed) Max. burn-up60MWd/kgHM90-100MWd/kgHM Deacy heat1200W/FA? Max. clad T600°C (long exposure time to creeps, 10y) 650°C ? (short exposure time to creep)

Fuel Transfer System Concepts MYRRHA - ALFRED comparison © SCKCEN ComponentItemMYRRHAALFRED StorageStorage periodSeveral decades Storage typeDry storageWet storage – in water Storage ContainmentIn canisterDirect contact Storage coolingGas convectionNatural convection TransferContainmentIn canister (probably) Providing limited shielding In canister (flask) Providing limited shielding Building requirementRed zone - No hot cellRed zone – No hot cell ReliabilityBack-up system Cleaning before storage Probably notno FA leak testyes

Control rod Overall Description Control rods is extracted downward and rise up by buoyancy in case of SCRAM. –The buoyancy is driving force for the emergency insertion it also keep the assembly inserted. The control mechanism push the assembly down thru a ball screw (for accurate positioning (like in BWR)). –motor and resolver (or encoder) are place atop the cover (at cold temperature (<100°C)), and are protected from radiation thru a shielding bloc. –its auxiliaries are enclose in carter filled the cover gas (gas plenum, Ar) there's no dynamic seals. – Thus there is a long pole linking the actuator (Ball srew) and the absorber assembly. The actuator is coupled to long rod by the SCRAM electromagnet.

Control rod absorber bundle 19 pins absorber bundle cooled by the primary coolant flow. –These pins are fitted with a gas plenum collecting the Helium and Tritium. He and H 3 produced, B 10 (B 10 (n,  ) Li 7 & a litle B 10 (n, H 3 ) 2  ). Logical place for this gas plenum would have been underneath the absorber in the cold area –but due space allocation interference, we had to place it above. add reflector pellet to reduce neutron leakage thought out this gas. Stack in cladding is (from bottom to top) –absorber (facing fuel when inserted), –reflector (facing fuel when extracted) – gaz plenum. it has one favourable side effect it increase the volume thus the buoyancy of absorber assembly

Safety rod Pneumatic insertion system :Description (1/2 ) The System constituted by 2 opposing piston on same shaft, the lift off piston and the insertion piston. –During normal reactor operation, safety rod is fully extracted upward holding force –The 2 chambers are at the same pressure (same feeding), the effective area of lift off piston is greater than the effective area of insertion piston. Lift off piston is connected to the purge valve via a large section pipe (2cm²) few pressure loss.

Safety rod Pneumatic insertion system: Description (2/2 ) The fast acting purge valve is directly actuated by the feeding line. –The feeding pressure keeps valve closed. –A flow restriction connect purge valve actuator to the lift off cylinder (flow restriction is integrated into valve itself ). The insertion cylinder is part of the accumulator thank. –volume of the accumulator is ≈10 times the volume increment due to the stroke. –The accumulator is fed through check valves (2in series )

Power cycle: general considerations Simple Rankine cycle have to be considered. Two options: –Re-heater (better efficiency but more complicated) –No Re-heater and just one optimized turbine for 100MWe Operational pressure 180 bar is mandatory In principle, second option is preferable Turbine by-pass valve in two steps  Heat rejection to atmosphere High pressure steam Pre-heater  Pb temperature control (steam cycle in operation) –It is demonstrated that T SG-inlet >335ºC Liquid water Heater  Pb temperature control (steam cycle stopped) –Water at 150 bar could be enough for heating the Pb in order to maintain it at >330ºC (saturation temperature at 150 bar = 342.2ºC) Task Secondary system conceptual design of the ETDR

Power cycle: two turbines-reheating layout Task Secondary system conceptual design of the ETDR

Power cycle: one turbine layout Task Secondary system conceptual design of the ETDR

Simple steam cycle has been chosen as secondary system Direct heat rejection is considered sharing the condenser Molten salt storage could be interesting in order to minimize difficulties on turbines due to the discontinuous reactor operation Liquid water heater included in order to guarantee Pb temperature faraway from its fusion point Questions to be clarified: –Too complicated molten salt storage? –Good to share the condenser between the heat rejection system and the power cycle? –Aerocondensers? –Others? Conclusions Task Secondary system conceptual design of the ETDR

Task 3.5 Decay Heat Removal Systems Several systems for the decay heat removal function have been conceived and designed for both ELFR and ALFRED –One non safety-grade system, the secondary system, used for the normal decay heat removal following the reactor shutdown –Two independent, diverse, high reliable and redundant safety-related Decay Heat Removal systems (DHR N1 and DHR N2): in case of unavailability of the secondary system, the DHR N1 system is called upon and in the unlike event of unavailability of the first two systems the DHR N2 starts to evacuate the DHR DHR N1: –Both ELFR and ALFRED relay on the Isolation Condenser system connected to four out of eight SGs DHR N2: –ELFR relay on a water decay heat removal system in the cold pool –ALFRED Some diverse concepts are under investigation: One of the possibility is to add other four Isolation Condenser to the other four SGs Considering that, each SG is continuously monitored, ALFRED is a demonstrator and a redundancy of 260% is maintained, the Diversity concept could be relaxed DHR Systems features:  Independence obtained by means of two different systems with nothing in common  Diversity obtained by means of two systems based on different physical principles  Redundancy is obtained by means of three out of four loops (of each system) sufficient to fulfil the DHR safety function even if a single failure occurs

Task 3.5 DHR N1 – Isolation Condenser ELFRALFRED

Del/DocTitleTaskResponsiblemmDate D03 Review and justification of the main design options of the LFR reference plant 3.1ANSALDO15 M D09 Secondary cooling concepts & feasibility study of heat recovery of the ETDR 3.4EA7M24 D10Conceptual design of the DHR system of the ETDR3.5ANSALDO13M24 D13 Plant layout and description of the containment system of the ETDR 3.6EA4M30 D31 Reactor Design Summary Report of the reference LFR, further development recommendations 3.1ANSALDO3M36 D32 Reactor Design Summary Report of the ETDR, further development recommendations 3.3SCKCEN3.5M36 T01 Description, functional sizing and drawings of the main components of the LFR plant 3.1ANSALDO15 M T02 Conceptual design of the SG dumping pressure wave system and test mock-up 3.2MERIVUS9M12 T03 Seismic Response Spectra of the Reactor building of the ETDR 3.6EA4M18 T07 Description, functional sizing and drawings of the main components of the ETDR 3.3SCKCEN12M24 T16Main components thermo-mechanical sizing of the ETDR3.3SCKCEN12M36 WP3 Deliverables & Technical Documents

WP3 Milestone & Planning MilestoneTitleTaskDateVerification M01LFR updated reference configuration3.1 M Report – T01 M04ETDR reference configuration3.3M24Report – D09, T07 M11 Reactor Design Summary Report of the reference LFR and the ETDR AllM36Report – D31, D32