LEADER WP3: Conceptual Design

Status

L. Mansaniluigi.mansani@ann.ansaldo.it

WP3 Tasks

• Task 3.1 - Reference plant configuration of a LFR (ANSALDO, CIRTEN, EA, JRC-IE, SRS)

• Task 3.2 - SG damping pressure waves system design (MERIVUS, CIRTEN, ENEA)

• Task 3.3 - Primary system conceptual design of the ETDR (SCK•CEN, ANSALDO, EA, SRS)

• Task 3.4 - Secondary system conceptual design of the ETDR (EA, ANSALDO)

• Task 3.5 - DHR system conceptual design of the ETDR (ANSALDO, SCK•CEN)

• Task 3.6 - 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

ELSYThe 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).

LIFUSThe 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 3.2 - 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 3.2 - 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 3.2 - 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 flangeCover 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

© SCK•CEN

Component Item MYRRHA ALFRED

Reactor In vessel storage YesIn-vessel fuel storage

no

Cooling period 420d (840d) (not fixed) 10d (not fixed)

FA Geometry Hexagonal wrapper, wired fuel pin

Hexagonal wrapper

Reshuffling At the bottom, by IVFH machine On top

Loading/unloading Top loading Top loading

FA Fuel vector (U,Po)O2 MOX–35%Pu(U,Po)O2 MOX–30%Pu

U,Po)O2 MOX–30%Pu(not fixed)

Max. burn-up 60MWd/kgHM 90-100MWd/kgHM

Deacy heat 1200W/FA ?

Max. clad T 600°C (long exposure time to creeps, 10y)

650°C ? (short exposure time to creep)

Fuel Transfer System Concepts MYRRHA - ALFRED comparison

© SCK•CEN

Component Item MYRRHA ALFRED

Storage Storage period Several decades Several decades

Storage type Dry storage Wet storage – in water

Storage Containment In canister Direct contact

Storage cooling Gas convection Natural convection

Transfer Containment In canister (probably)Providing limited shielding

In canister (flask)Providing limited shielding

Building requirement Red zone - No hot cell Red zone – No hot cell

Reliability Back-up system Back-up system

Cleaning before storage

Probably not no

FA leak test yes yes

Control rodOverall 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 rodabsorber 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 H3 produced, B10 (B10 (n,) Li7 & a litle B10 (n, H3) 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 TSG-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 3.4 - Secondary system conceptual design of the ETDR

Power cycle: two turbines-reheating layout

Task 3.4 - Secondary system conceptual design of the ETDR

Power cycle: one turbine layout

Task 3.4 - 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 3.4 - 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

Main Feed water line

Main steam line line

IC Steam line line

Water storage tank

Isolation condenser1 out of 4 systems

PoolLarge Pool

Safety relief valves

Main feed water isolation valve

Main steam isolation valve

Steam generators(1 out of 4)

Condensate Isolation Valve

Return condensate line

Del/Doc Title Task Responsible mm Date

D03Review and justification of the main design options of the LFR reference plant

3.1 ANSALDO 15 M0831-12-11

D09Secondary cooling concepts & feasibility study of heat recovery of the ETDR

3.4 EA 7 M24

D10 Conceptual design of the DHR system of the ETDR 3.5 ANSALDO 13 M24

D13Plant layout and description of the containment system of the ETDR

3.6 EA 4 M30

D31Reactor Design Summary Report of the reference LFR, further development recommendations

3.1 ANSALDO 3 M36

D32Reactor Design Summary Report of the ETDR, further development recommendations

3.3 SCK•CEN 3.5 M36

T01Description, functional sizing and drawings of the main components of the LFR plant

3.1 ANSALDO 15 M1231-12-11

T02Conceptual design of the SG dumping pressure wave system and test mock-up

3.2 MERIVUS 9 M12

T03Seismic Response Spectra of the Reactor building of the ETDR

3.6 EA 4 M18

T07Description, functional sizing and drawings of the main components of the ETDR

3.3 SCK•CEN 12 M24

T16 Main components thermo-mechanical sizing of the ETDR 3.3 SCK•CEN 12 M36

WP3 Deliverables & Technical Documents

WP3 Milestone & Planning

Milestone Title Task Date Verification

M01 LFR updated reference configuration 3.1 M1231-12-11

Report – T01

M04 ETDR reference configuration 3.3 M24 Report – D09, T07

M11Reactor Design Summary Report of the reference LFR and the ETDR

All M36 Report – D31, D32