Flexible Operations - Considerations for Existing and … · Flexible Operations - Considerations for Existing and New Builds ... smart inverters) ... • 2014 Completed study to

Sherry Bernhoft, EPRI

Program Manager

IAEA Technical Meeting on Flexible Operations Erlangen, Germany October 6-8, 2014

Flexible Operations - Considerations for Existing and New Builds

2 © 2014 Electric Power Research Institute, Inc. All rights reserved.

Three Key Aspects of EPRI

Independent Objective, scientifically based results address reliability, efficiency, affordability, health, safety and the environment

Nonprofit Chartered to serve the public benefit

Collaborative Bring together scientists, engineers, academic researchers, industry experts

Independent

Collaborative

Nonprofit


Nuclear Power Membership is Global

U.S. Nuclear Power Plants

Source: NEI Website, 2009

U.S. Participants Non-U.S. Participants Global

Breadth and Depth

• All U.S. nuclear owners/operators

• 100 reactors

• 20 countries, >220 reactors

• >75% of the world’s commercial nuclear units

Participants encompass most nuclear reactor designs


Need for Flexible Operations

Drivers• Variable

Generation, RPS,EnvironmentalRegulations

• Fuel Price Uncertainty, Power Market Effects

• Consumer Effects, Higher Load Variability

• Viable Cycling of Conventional Generation (Coal, Natural Gas, nuclear, hydro)

• Polygeneration (Cycle between output products)• Renewables as a Solution (Concentrating solar + thermal storage,

wind for active power control, geothermal for load following)

• Electricity Energy Storage (Buffer for bulk energy, ancillary services, T&D infrastructure, customer energy management)

Trans

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ed Po

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yste

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ith En

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ed Fl

exibi

lity

• Clean Flexibility (Fast ramping natural gas turbines, DER for emissions reduction by switching fuels, wind/solar forecasting)

• Transmission (Power electronics devices, HVDC, dynamic ratings)• Distribution (Enhanced reconfigurability via DMS, smart inverters)

• Power System Balancing & Operation (Situational awareness, operating practices, new power market products, inter-area coordination)

• Power System Planning (Renewable integration planning, flexibility metrics, advanced assessment tools and models)

• Customer Behavior & Adoption (Energy efficiency, fast-reacting loads, distributed storage, dispatchable DER, communications for connectivity)

Solutions


Flexible Nuclear Power Plant Operation

• Existing plants: – Need to consider transition to flexible

operations, or – Need to increase range of maneuverability

• New builds need to consider flexible

operations: – Large load on a small grid – Utility generation mix and dispatch order

considerations – Periods of low load demand


NPP Flexible Plant Operations – Project Overview

Phase 1 – Gap Matrix

Phase 2 – Define Current Plant Capabilities

Phase 3 – Assess Increased Maneuverability

Phase 4 – R&D for Long-Term Asset Management

Planned 2015-2017

‘Approach to Transition Nuclear Power Plants to

Flexible Operations’*

Product 3002002612 Published Jan 2014

Available on EPRI.com

*Developed with input from INPO


What We Learned… • Need to establish protocol with the ISO/TSO • Plant modifications maybe needed • Challenges at end-of-cycle • Volume of waste water generated • Protection of secondary components • Accident and transient analysis • Changes are needed to operating procedures, and

maintenance programs • Training needs to a part of the plan

Existing plants – need a formal change management plan

New builds – incorporate into the design and licensing basis


Approach – Three Steps: 1. Strategic Assessment

– Future grid demands – Existing capabilities – Integrated utility generation

capabilities Define desired FPO envelope

2. Tactical Considerations Select FPO approach Determine if modifications are

needed

3. Implementation – Establish a formal protocol with the

ISO/TSO – Develop the transition strategy Change management plan


1. Strategic Assessment • Future grid demands

– Variations in power demands • Daily • Weekly • Seasonal

– Variability on the grid (renewables and hydro)

– Regional economic growth or stagnation

• Assess the existing capabilities for FPO – Design basis – Licensing basis – Operating procedures – Operating experience

• Asses integrated utility generation capability – Portfolio and dispatch options

Define the FPO envelope:

Rate

Depth

Duration

Frequency


2. Tactical Considerations

• Power control methods – Power control options

• Control rods • Steam bypass

– Core management considerations • Pellet-clad interaction • Axial power offsets • Fuel burn-up

– Core instrumentation and control • Instrumentation system design

• Primary-side components – RCS components – Steam Generators – Water Chemistry

• Examples of considerations:

– Full absorber of partial absorbers (grey) control rods

– Reduce reactor power or steam bypass to condenser

– Primary side chemistry

management • Soluble poisons • Water processing • Effluent water management

– Fatigue management


2. Tactical Considerations –cont.

• Balance of Plant – Turbine mechanical system – Condensate and feedwater – Moisture separators and

reheaters – Condenser – Generator – Instrumentation

• Secondary Water Chemistry • Operational considerations

– Operating procedures – Program procedures – Staffing level review – Training – Communications

• Examples of considerations – Turbine control valve design-

partial or full arch steam emission

– Flow accelerated corrosion program

– Regions of flow instability and ‘harmonics’

– Feedwater flow control at low and changing power levels


Implementation

• Training and communications plan – Recognize the paradigm

change • Establish FPO protocol with the

ISO/TSO • Develop a transition strategy

– Staged approach vs. all at one time

• Change management plan – Accident and transient

reanalysis – Licensing/regulatory approvals – Plant modifications – Procedure changes

• FPO Protocol: – Establish periods of ‘No FPO’ – Amount of prior notification

required – Limits for duration and

frequency of power maneuvers

– Rate and depth of power maneuvers

• INPO guidance for Change Management Plan


NPP Flexible Plant Operations – Project Overview

Phase 1 – Gap Matrix

Phase 2 – Define Current Plant Capabilities

Phase 3 – Assess Increased Maneuverability

Phase 4 – R&D for Long-Term Asset Management

Planned 2015-2017

‘Approach to Transition Nuclear Power Plants to

Flexible Operations’*

Product 3002002612 Published Jan 2014

Available on EPRI.com

*Developed with input from INPO


Phase 4 – Long-Term Asset Management R&D

• 2014 Completed study to identify plant secondary side components vulnerabilities to: – High-cycle and low-cycle fatigue – Flow-induced vibration – Pump cavitations and valve chatter – Flow accelerated corrosion

• 2015 - 2017 In priority order: – Fuel integrity guidance – Chemistry, Low Level Waste and Radiation

Management guideline changes – Impacts on the secondary side and revision to

the preventative maintenance database – Fatigue impacts assessment on primary side – Pilot plant to demonstration of an integrated

monitoring system concept

Operating experience shows that there is a latency effect

on system wear and tear.

Intertek Asset Integrity Management (AIM)

Fuel Integrity Guidance


Phenomena of special interest in power cycling

PCMI PCI-SCC

Nearly 5% of recent fuel failures are duty related; linked to power maneuvering and operations


EPRI Falcon Code Models Fuel Behavior

• Falcon follows a single fuel rod behavior in response to its power history

• Power history through the cycle defines the temperature distribution within the fuel rod during operation

• Clad corrosion, internal pressure, rod diameter and elongation;

• Fuel temperatures, cracking patterns; • Pellet clad interactions and gap

closure; etc. • Falcon will be modified for flexible

operations • Guidance will be developed for PCI

Chemistry and Radiation Safety


2015 - 2017 Overview • Chemistry Controls

– Understanding the impact on the water chemistry Guidelines • Challenges (PWR Example)

– Primary Chemistry – impact of maintaining boron-lithium controls and impact on other systems

• Corrosion product transport and control parameters impact • Reactivity management challenges to operators • Increased demand for boric acid and boric acid tank operations • Increased demands on cleanup system resins

– Water Treatment Systems • Challenges

– Truck fed systems – In-house water treatment plants

– Chemical Injection systems

• Low Level Waste (RW Systems) and Radiological Plant Effluents – Increase demands for waste processing systems and resin/filters – Potential increase in plant effluents

• Radiation Management – Dose rate impact in light of industry incentives for reduced exposure


Fuel Reliability

• Recent revision of Primary Water Chemistry Guidelines moved fuel related chemistry guidance to Primary Guidelines

– Control parameters key for minimizing fuel crud source terms

– Diagnostic parameter updates in recent revision related to monitoring crudding issues – specifically during transients (power reduction, startup, shutdown)

Table 3-3 Reactor Coolant System Power Operation Control Parameters (Reactor Critical) - RECOMMENDED Control Parameter

Sample Frequency

Action Level 1 2 3

Lithium, ppm 3/wk(3) (4) --- ---

Footnote 3 establishes that the sampling frequency be increased to once every four to six hours for power reductions of 10% or greater from full power lasting more than four hours

Crud-Induced Localized Corrosion (CILC)

Failures

Crud-Induced Power Shifts (CIPS) Issues

Thick crud in small area = surface

dryout


Wrap-up

Chemistry • Better understanding the CRUD corrosion impact

• BWRVIP Chemistry Guidelines

• PWR Chemistry Guidance

• PWR Primary Water Chemistry Guidance

• PWR Secondary Water Chemistry Guidance

Radiological Environmental Program • Understanding the liquid and gaseous processing limitations and

impact on radiological effluents

Radiation Management and Source Term

• Impact of corrosion product transport to fuel surfaces

• Impact of activated corrosion products transport ex-core

• Impact of Shutdown Chemistry controls and dose rates

Low Level Waste • Liquid Waste Processing

• Impact on Waste Generation

Impact on Plant Secondary Side and Preventative Maintenance Database


Secondary Side Vulnerability Study

Secondary Side Component Impact Study –completed in 2014

• The study focused on secondary

plant components and the potential impact of Flexible Plant Operations on these components

• Flow accelerated corrosion program

is included as a consideration on the matrix


Flexible Plant Operations- Changes to PMBD

EPRI’s Preventative Maintenance Basis Database (PMBD) is based on full power operations. PMBD will be amended to support Flexible Plant Operations.


Integrated Monitoring System – Pilot Plant

• Identify pilot plant • Select locations that are ‘leading indicators’

of accelerated damage during periods of power changes and reduced power

• Using installed instrumentation, modeling and selected additional sensors install a wireless system that can monitor, detect and provide real time feed back to the operators

• Operators can use this information to move the plant to a power level where there is less impact on the components

• The results of the pilot study will be used to support designing a final system

Effect on Primary Side Components


Flexible Operations and Its Effects on the Primary System

• Issue Statement – Change in primary system operational variables such as

flow rate and temperature may adversely affect primary system components

• Potential damage mechanisms

– Environmentally assisted fatigue (EAF) – Stress corrosion cracking – Flow induced vibration – Acoustic resonance


Design Transients and Load Following Transients

• Graded Approach – Define two situations for investigation:

• Step 1: Power range for load change is limited to (100% - 80%) Pr at a rate of 1% Pr/min to 2% Pr/min, such that

– effects on system defined easily and showing insignificant component impact • Plants benefit in the near term.

• Step 2:The unit shall drop load from 100% Pr to a minimum load of 30% Pr (the lowest power level from which minimal plant actions are needed to rise to 100% pr) at a rate of 5% Pr/min, hold at 30% load for 6 hours, then rise to 100% Pr at 5% Pr/min.

– Perform transient analysis of primary system and identify adverse effects and limiting conditions.

Summary


Next Steps

• Technical Advisory Group (TAG) has been formed – Key stakeholders – Ensure coordination and prioritization

of projects to support safe, reliable flexible operations

• Evaluate future project needs

– Human performance improvements – Cost of flexible operations – Value or benefit of being able to

contribute to flexible operations


Together…Shaping the Future of Electricity

Documents

Flexible Operations - Considerations for Existing and … · Flexible Operations - Considerations for Existing and New Builds ... smart inverters) ... • 2014 Completed study to