Nuclear Power Plant Flexibility at EDF: 30 years of experience€¦ · What is Plant Flexibility ?...

Nuclear Power Plant Flexibility at EDF:30 years of experience

Patrick MorilhatProgram Director, Nuclear PerformanceEDF Research and [email protected]

© EDF 2019

Presented at the 2019 Energiforsk Nuclear Annual Conference on”Flexible nuclear power and ancillary services”2019, 23 - 24 january, Stockholm, Sweden

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Disclaimer

This presentation is aimed at presenting EDF experience on Nuclear Plant Flexible Operation to the EnergiforskAnnual Nuclear Conference 2019 and do not constitute an offer of services for sale in any jurisdiction. No reliance should be placed on the accuracy, completeness or correctness of the information or opinions contained in thispresentation. None of EDF or any of its affiliates, advisors or representatives, shall bear any liability (in negligence or otherwise) for any loss arising from any use of this presentation or its contents or otherwise arising in connection withthis presentation.

All statements other than statements of historical fact included in this presentation, including, without limitation, thoseregarding the financial position, business strategy, management plans and objectives for future operations of the Group, are forward-looking statements. These forward-looking statements involve known and unknown risks, uncertainties and other factors, which may cause actual results, performance or achievements of the Group, or industry results, to be materially different from those expressed or implied by these forward-looking statements.

Forward-looking information contained in this document only apply at the date of this document and EDF does not commit to updating them later to reflect subsequent facts and circumstances or occurrence of unanticipated events.

Nuclear Power Plant Flexibility – Energiforsk 2019

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WORLD’S No. 1 ELECTRICITY COMPANYEstablished in Europe, especially France, the United Kingdom, Italy and Belgium

Diversified low-carbon energy mix based on nuclear power and renewables

EDF COVERS ALL ELECTRICITY ACTIVITIESGeneration

Transmission and distribution

Supply

Energy services

LEADER IN LOW-CARBON PRODUCTIONNo. 1 producer of nuclear electricity in the world

No. 1 producer of renewables in Europe

No. 3 European operator of energy services

EDF AT A GLANCE

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Nuclear & Renewables: two pillars of France’s low carbon electricityKey Figures for EDF France Mainland

Gas 2%Coal 2%

Hydropower andother renewables

22%Nuclear

68%

Fuel oil 6%

Gas

2%

Coal1%Hydropower and

other renewables

9%

Nuclear

88%

92.3 GWe 432.3 TWh

Installed capacityGWe

Electricity generation (2017)TWh

96% carbon-free generation

CO2 emissions (2017)gC02/KWh


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Flexible Operation at EDFLargest fleet in Europe

France: 63 GW, 400 TWh, 59 units, 19 sites,

3 PWR series in operation; more than 1600 year of Operating

Experience

900 MW : 34 units, 31 GW, average age 34 years

1300 MW : 20 units, 26 GW, average age 24 years

1500 MW (N4) : 4 units, 6 GW, average age 19 years.

1650 MW (EPR) : 1 unit (2019)

9 reactors in decommissioning

UK: 8,9 GW, 14 AGR + 1 PWR, 8 sites

China : 2 EPRs in JV with CGN


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Flexible Operation at EDFA long story

The first French NPP originally designed for base load

Early 80’s, decision taken to improve NPPs Load Following capabilities, leading to studies,

modifications and administrative authorizations

Modifications implemented :

mechanical design : surge line, spray line, charging line

pressurizer control loops

control rod drive mechanisms

introduction of a new core control mode (grey mode)

Flexible Operation has been successfully implemented at EDF NPPS for 35 years with

manageable impacts


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Flexible Operation at EDFMarket Price setting and merit order

Variation of commodities prices

Coal, Gas , CO2

Variation of demand

RES development


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What is Plant Flexibility ?Power variations recorded in June 2013 at a French 1300 MW NPP

-200

0

200

400

600

800

1000

1200

1400

very low demand during week-end

hot short shutdown

low demand during week-end

operation at minimum load

Frequency

control

most of time

MW


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Load following : large load variation program agreed in advance with the grid operator, P0 is a setpoint manually set by plant operator, 2 large variations/day, [100%-20%], ramp up/tramp down 30 min.

Frequency control : minor automatic load variations aimed at controlling grid frequency (50 Hz+/- 0.5Hz in Europe)

k.Df : primary frequency control (2% Pn), short-term adjustments (less than 30 s.)

N.Pr : secondary frequency control (5% of Pn), adjustments within 15 min.

P = P0 + k. Df + N.Pr

Load followingOutput MW Frequency control

What is Plant Flexibility ?Basics of flexible operation


Reactor core thermal power is controlled using two

devices that absorb neutron:

Control rod: absorber elements inserted in/extracted

from the core

allow real-time control of the uranium fission process

inserting rods creates power distortion between lower and

upper part of core. “Grey” rods lessen the deformation

Boric acid reactivity control: injection/dilution of a

soluble neutron absorber added to the reactor

coolant

ensure and even power and flux distribution

boron dilution to counteract Xenon effects limits the range

of power radiation in the last third of the fuel cycle

What is Plant Flexibility ?Control of reactor core thermal power


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Lessons learned

SAFETY

FUEL

CHEMISTRY

WASTE & THE ENVIRONEMENT

OPERATION & MAINTENANCE

SKILLS

Variations in power stay within areas of operation for which

reactor safety was demonstrated

Safety events (IAEA INES level 0 or 1) due to load following

stay rare. No additional LCO entries (Limited Conditions of

Operation). No additional SCRAM (automatic shutdown)

Primary circuit stay stable in pressure, low variations in

temperature. Number of variations is monitored and

registered to remain below initial design allowance.

As this limit is far from being reached, 60 years lifetime

extension is possible


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Lessons learnedFuel power and temperature variations stay beyond safety

limits proven to be hazardless on fuel integrity. Those limits

allow flexible operation everyday if necessary.

Energy produced at intermediary power is limited to avoid

local hot spot due to insertion/withdrawal of control rods

Operating time at reduced load is limited to avoid fuel deconditioning regarding pellet –cladding interaction

Initial credit of 30 or 60 days (depends on fuel and type of cladding) are sufficient to allow flexible operation all along

the cycle.

SAFETY

FUEL

CHEMISTRY



SKILLS


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Lessons learnedNo noticeable impact on chemistry nor radiological

condition for workers.

Boron / lithium equilibrium needs frequent adjustment because boron concentration varies during load following.

Hydrogen concentration inside primary circuit needs

continuous monitoring by control room operator.

Providing this monitoring and a good coordination between

chemistry and operation, no negative impact on chemistry has been noticed.

SAFETY

FUEL

CHEMISTRY



SKILLS


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Lessons learnedNo noticeable additional activity released in the Environment

Liquid wastes Primary liquid wastes (dilution, boration) mostly treated (gas

stripper, evaporator to separate boron from water) and

recycled in boron and demineralised water tanks.

Final liquid wastes volumes are kept low, no noticeable impact

on activity released

Gaseous wastes A daily load variation has No noticeable impact on activity

released

Solid wastesSlight increase of spent ion exchange resins, wastewater

filters, but no impact on waste management (storage and

emission limits)

SAFETY

FUEL

CHEMISTRY

WASTE & THE ENVIRONMENT


SKILLS


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Lessons learned Impact on Maintenance :Load variations have nearly no impact on primary system

Increased number of design conditions in temperature (mainly

surge line pressurizer), but compatible with vessel aging.

Control rod drive mechanisms to be changed after a defined

number of manoeuvres (cost/dosimetry)

Balance of Plant impact : preventive Maintenance Program

need to be adjusted (leakage at welded joints or by erosion of

pipes or ageing of heat exchangers)

additional corrective maintenance during outage :

unnoticeable

Impact on GenerationForced Loss Rate (FLR) : kept low, no clear distinction between

FLR due to frequency regulation and FLR due to load following

SAFETY

FUEL

CHEMISTRY



SKILLS


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Lessons learned Load following is part of control room operator training and

qualification, full scope simulators are used for training

Technical Specifications and procedures give general

instructions

Good understanding of xenon, water, boron, rods effects is

required. As xenon effect is delayed, control room operator’s attention must be kept upon reactor control several hours

after a load following

Advanced Computerized Aids for the Control Room Operators help control room operators to forecast xenon

and to prepare dilution / boration strategy

SAFETY

FUEL

CHEMISTRY



SKILLS


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Flexible Operation at EDFLong term perspective and prospective studies

Ensure delivering a Nuclear and Renewable Alliance to maintain a very low carbon energy system

Future needs for nuclear plant flexibility will depend on:

- demand and export/import balance (level of cross boarder interconnexions)

- share of non-dispatchable Renewable Energies

- other flexibility levers (ex storage)

EDF is exploring several nuclear+renewable energy scenarios to identify technical barriers, in compliance with the

French law on Energy transition (2015) and the related Multiannual Energy Plan (2018) aimed at preparing for

tomorrow’s energy system

EDF has recently launched to major initiatives :

- Solar Plan : development of + 30 GW in France within the period 2020-2035

- Storage Plan : development of + 10 GW of electric storage capacities in the world before 2035


| 18Copyright EDF | 2018

Flexible Operation of NPPs at EDF proven feasible for 35

years

Requires an appropriate design

Needs trained operators skills

No effect neither on safety nor on the Environment

No noticeable additional maintenance cost

Low impact on unplanned capability load factor

On-going studies of beyond 2040 Nuclear/Renewable

scenarios and impacts


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Nuclear Power Plant Flexibility at EDF: 30 years of experience€¦ · What is Plant Flexibility ?...

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