Centrum výzkumu Řež s.r.o.

S-ALLEGRO helium loop

Otakar Frýbort, Tomáš Melichar,

Jana Kalivodová

VINCO Webinar, 8/2018

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Centrum výzkumu Řež s.r.o, project

Research organisation, part of UJV group, focused on R&D in energy

(especially nuclear), approx. 380 employees

SUSEN project – focused on building of research infrastructure to extend

energy research possibilities

2016 – end of building phase

2013 – 2020 – R&D outputs and proving sustainability

Build of large-scale

experimental facilities allowing

R&D in the field of GENIV and

fusion reactors

Active SCW loop

Active HTHL loop

sCO2 loop

S-Allegro loop

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GFR Reactor

One of „GENIV“ reactors

Gas-cooled fast reactor

Brayton cycle for energy

conversion working up to 850°C

2005: Project of GFR 2400 MWt

reactor and GFR demonstrator

ALLEGRO 75 MWt by CEA

2009: Modification of the French

government – resources redirected

to SFR only

2010: Allegro consortium V4G4 –

development of GFR demonstrator

in the Central Europe under CEA

scientific support

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Reference concept - Allegro

Nominal Power (thermal) 75 MWReduced power is being considered in the range

30 – 75 MW.

Nominal Power (electrical) 0 MW

Power density 100 MW/m3

Reduced power density is being considered in the

range

50 – 75 MW/m3.

Fuel

MOX/

SS cladding

Start-up core.

Feasibility of LEU UOX for the start-up core is being

investigated.

UPuC/

SiCSifC claddingLong term core.

Type of fuel assembly Hexagonal wrapper and wired fuel rods

Number of fuel rods per

assembly169

Number of fuel assemblies 81

Number of experimental fuel

assemblies6

Number of control and

shutdown rods10

Primary circuit coolant Helium

Secondary circuit coolant Water Gas is being investigated

Tertiary circuit coolant Air Atmosphere

Primary pressure 70 bar

Core inlet/outlet

temperatures260/516 °C Should be upgraded for full core refractory fuel.

Number of primary loops 2

Number of secondary loops 2

Number of DHR loops 3 Directly connected to the primary vessel

DHR circuits coolant Helium

DHR intermediate circuits

coolantWater

DHR heat sink Water pool

Number of accumulators 3 Filled with Nitrogen

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Experimental S-Allegro loop

PURPOSE

Large-scale facility for development of GFR concept ALLEGRO

To verify the basic safety features and system behavior of the

ALLEGRO

To verify the decay heat removal system using dedicated DHR

loop

Testing of components of HTHe systems

Generation of data for codes validation

Delivered by ATEKO a.s. company within SUSEN project

Build in Pilsen, West Bohemia

Currently at the testing stage

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Experimental S-Allegro loop

PRESSURE

VESSEL

SECONDARY HX

PRIMARY HX

PRIMARY

CIRCULATOR

DHR COOLER

DHR CIRCUIT SECONDARY

CIRCUIT

SECONDARY

CIRCULATOR

Experimental S-Allegro loop

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Experimental S-Allegro loop

Main parameters of the primary

and DHR circuit1 primary loop

1 DHR loop

medium helium

pressure 7 MPa

power 1 MW

tin (model core) 445°C

tout (model core) 850°C

flow rate (I. loop) 0,5 kg/s

the compressor enables regulation in the

range of 10-100%

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Experimental S-Allegro loop

Main parameters of the secondary

circuitmedium helium

pressure 6,5 MPa

tin (HX) 365°C

tout (HX) 820°C

flow rate 0,5 kg/s

the compressor enables regulation in the

range of 10-100%

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Experimental S-Allegro loop

Main parameters of the

tertiary circuitmedium water

pressure 1,1 MPa

tin (HX) 28 - 35°C

tout (HX) 45°C

flow rate 17,2 kg/s

Key Components of the loop – Reactor vessel

Basic component, heart of the helium loop

5 flanges enable to connect 2 primary and 3 DHR circuits

1 DRH and 1 primary circuit connected, 3 flanges are blinded

1.4541 steel used for vessel

Height 2990 mm, diameter 620 mm

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Key Components of the loop – Heating system

The heating system represents the reactor core

Electric heating based on resistive wire

Ceramic body, KANTHAL wire

Electrical heater with max. power 1050 kW which corresponds to

ALLEGRO decay heat value

Heater control from 0 – 100%

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CFD analyses of the heater

Key Components of the loop - main HX

1 MW gas (helium / helium) heat exchanger

coiled tube type

268 coiled tubes – ø10,2 x 2,3mm

Total lenght of coiled tubes – approx. 1 300 m

T (I.): 850 - 445°C

T (II.): 365 - 820°C

only 2 flanges - coaxial piping for both I. and II. Circuit

1.4959 and 1.4541 steel used for HX

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Key Components of the loop - Helium circulators

Primary and secondry circulatornominal mass flow rate = 0,5 kg/s

Tin = +460°C

nominal compression ≤ 1 bar

speed = 76 000 min-1

gas bearings

mechanical power = 16,5 kW

DHR circulatornominal mass flow rate = 0,04 kg/s

Tin = 210°C

nominal compression ≤ 0,5 bar

speed = 150 000 min-1

gas bearings

mechanical power = 1 kW

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Key Components of the loop – Secondary HX

secondary HX 1 MW gas (helium / water) heat exchanger

U - tube type

57 – ø16 x 2,5mm

T (II.): 820 - 355°C

T (III.): 30 - 45°C

3 flanges - coaxial piping on II circuit

1.4541 steel used for HX

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Key Components of the loop – coaxial valves

Coaxial valves2 types

shut-off valve (in I. circuit)

cross-flow valve (in DRH circuit)

key components providing passive safety of whole system

key role in the decay heat removal system

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SHUT-OFF VALVE

CROSS-FLOW

VALVE

Key Components of the loop – cross valves

Developed at CVR

Optimized using CFD and FEM analyses

High requirements on fabrication and

components quality

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Key Components of the loop – DHR loop

DHR loopDHR = Decay Heat Removal ≈ 5% of nominal power

DHR strategy is based on the following principles:

a natural convection flow

is preferred following shutdown

height of the loop affects natural convection

this is possible when the circuit is pressurized

a forced flow

is required immediately after shutdown – when depressurized

necessary circulation occurs in dedicated DRH loop

the I. circuit must be reconfigured to allow DHR

key valves role

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Controlled leakage system

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Simulation of accident (LOCA) conditions

4 valves for controlled leakage

Max. pressure gradient 0,5 MPa/s

Current status

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Commissioning test

The speeds of the TC101 and TC102

turbocompresors were regulated at the

projected limits of 20,000 to 80,000 rpm

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In a complex test, a

temperature of 850 ° C

(TT813) was achieved in the

R101 reactor vessel model.

Tests of the technology were carried out according to the plan of individual and

complex tests for 120 hours without technology failure. During test run, operational

status tests were performed including standard technology approach and standard

shutdown technology. The S-Allegro loop was controlled from the control system

through an operator station equipped with SW APROL, which allows the operator to

customize the operator's requirements.

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Experimental possibilities

Steady state conditions and normal transientsControlled reaching of normal parameters (by steps)

Main goal is to collect the steady state data for basic

setup and tuning of computational codes

LOFA - Loss Of Flow AccidentSet up of steady state conditions

Switch the main circulator off

Automatic fast decreasing of the heater power with

predefined function (simulation of residual heat)

Closing of the coaxial valve on main loop and simultinous opening of DHR coaxial valve

Start up of the DHR compressor

This test will not be one of the first experiments and needs to be carefully simulated using of system code

SBO - Station BlackOutSimilar conditions as the LOFA experiment

without DHR circulator

This test will not be one of the first experiments and needs to be

carefully simulated using of system code

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Experimental possibilities

LOCA - Loss Of Coolant AccidentSet up of steady state conditions

Opening of selected leakage valve

Continuation according the requirement (back-up pressure, …)

This test will not be one of the first experiments and needs to be

carefully simulated using of system code

Transient from forced to natural circulationReaching of the steady state conditions with the DHR loop and running DHR circulator

Switch of the DHR circulator

This experiment simulates the DHR compressor failure when the reactor is swiched off

DHR valve failure during normal operationReaching of steady state conditions with primary loop and the main circuit

Opening of the DHR coaxial valve

Loss of heat sink – II. Circuit failureSecondary circuit circulator failure

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Experimental possibilities

Loss of heat sink – III. Circuit failureLoss of mass flow rate in the tertiary circuit during normal operation

(Heavy) Gass injectionAnother posibility to SBO or LOFA

Testing of the gas injection as the establishing of natural circulation in the DHR loop

Basic natural circulation phenomenon experiments

Investigation of establishing of natural circulation after heater start up

It is not any accident scenario

This experimental data will be more usable for basic research

Testing of scaled down component

The loop can be modified ie. For testing of another kind of coaxial valves, …

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Other helium activities at CVR

AREAS

Research of materials behavior in the

HTHe environment

Helium chemistry – purification of He

coolant

Thermo-hydraulic experiments and

calculations

OTHER INFRASTRUCTURE

High temperature helium loop HTHL-1

for out-of-pile experiments

High temperature helium loop HTHL-2

for in-pile experiments in the LVR-15

reactor

High temperature furnaces

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Conclusions

S-Allegro facility has been built at CVR (Pilsen) within SUSEN

project

The facility is intended for verification of GFR safety systems,

testing of HTHe components and for generation of T-H data for

codes validation

Planned experiments (2018) - national projects; international

collaboration expected

Apart from the T-H experiments, CVR is also involved in RD

support for HTGR: structural materials behavior in HTHe

environment, controlling of helium chemistry, He purification

and recycling and development of computational tool within

both national and European projects

Thank you for your attention!

Centrum výzkumu Řež

Hlavní 130

250 68 Husinec-Řež

Czech Republic

www.cvrez.cz

EVROPSKÁ UNIE

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