Current status of NPP C

1
Current status of NPP CI in the United Kingdom
21st Meeting of the Technical Working Group on
Nuclear Power Plant Control and Instrumentation,
23-25 May 2007, Vienna

• T P Smyth
• AMEC NNC, Knutsford, Cheshire, UK

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Current status of NPP CI in the United Kingdom

• Nuclear Power Plants in the UK
• Status of CI at AGR nuclear plants
• Reactor Protection Systems
• Data Processing Systems
• Refuelling machines
• Status of CI at PWR plant
• Simulators
• Status of regulatory environment affecting CI
• Recommendations

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Nuclear Power Plants in the UK (1)
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Nuclear Power Plants in the UK (2)?

• Electricity sources
• 20 nuclear
• 37 gas
• 34 coal
• Need to plan for energy replacement
• 7 plants will close in next 11 years
• 14 reactors
• 7294 MWe
• 13 of electricity sources
• North Sea oil and gas will be limited in future
• 23 May 2007
• Government announces 20 week consultation process
• Government wants to take decision this year
• No public money

5
AGR Reactor Protection Systems (1)?
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AGR Reactor Protection Systems (2)?

• Obsolescence of equipment
• Difficulty in obtaining spares
• Repairs
• Replacement
• Analogue trip units
• Neoprene degradation
• New equipment
• Majority of protection parameters have been
  addressed

7
AGR Reactor Protection Systems (3)?

• Neoprene insulation degradation
• Magnox Oldbury power station
• Degradation with age
• Perishing
• Sweating
• Hygroscopic
• Becomes conductive - resistance lt 1 M?
• Stray currents in sensitive circuits
• Thermocouple amplifiers

8
AGR Reactor Protection Systems (4)?

• Neoprene insulation degradation?

9
AGR Reactor Protection Systems (5)?

• Neoprene insulation degradation

10
AGR Reactor Protection Systems (6)?

• Neoprene insulation degradation
• Survey of all safety equipment
• Presence of neoprene
• State of neoprene
• Circuit function
• Replacement equipment at older stations
• Obsolescent anyway
• Repairs at newer stations
• Heysham 2 / Torness
• 4 years work, 2 more years to finalise all
  equipment

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AGR Reactor Protection Systems (7)?

• Neutron Flux measurement systems
• AGR detectors located in core at 8 locations
• High temperatures
• Detector spares
• Wide range detector integral cable
• Manufacturing spares re-establishing production
  processes
• Currently a batch of 10 in progress
• Electronic units
• Neoprene
• Complete refit
• Repairs at Heysham 2 / Torness

12
AGR Reactor Protection Systems (8)?

• Diverse Guardline upgrade
• Hinkley B / Hunterston B / Dungeness
• Driven by licensing basis for nuclear power
  plants
• Large subset of Main Guardline parameters
  duplicated
• From 1995 to 2000
• Heysham 2 / Torness had diverse guardlines from
  the outset.
• Hartlepool / Heysham 1 were judged to have
  adequate diversity in protection systems

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AGR Data Processing Systems

• Safety claims on equipment
• Some reactor control functions
• Some alarms
• Hinkley Point B
• New DPS installed (1999)?
• Dungeness B
• New DPS being installed
• Control / equipment protection functions
  segregated
• Other AGR's
• Stabilization of equipment
• Adequate spares provision / hardware support.
• Improved air conditioning
• Limited re-manufacturing (optical transceiver
  boards)?

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AGR Refuelling Machines (1)?
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AGR Refuelling Machines (2)?
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AGR Refuelling Machines (3)?

• Online refuelling
• Stringent safety requirements
• Equipment obsolescence
• Key focus at present
• Heysham 2 / Torness
• Replacement of Reypac controllers with Siemens S7
• I/O replaced, emulates original equipment
• Reypac controller replacement in progress
• Software reverse engineered and ported
• Safety functions partitioned
• Safety standards
• Modern standards considered when replacing
  equipment

17
PWR Principal CI Systems (1)?

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PWR Principal CI Systems (2)?

• Equipment Life cycle management
• Review of equipment status
• Review of spares holdings
• Participation of OEM (Westinghouse)?
• HICS
• Optical transceiver units obsolete
• New units re-engineered by Westinghouse
• Adequate spares manufactured

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Simulators

• Sizewell B
• On site
• Replaced in 2003
• Duplicate DPS
• Can be modified at the same time as the main DPS
• WANO recommendation
• AGR's
• Goal was to establish a simulator at each site
• Hartlepool - new simulator
• Heysham 2 / Torness
• Upgraded to increase fidelity
• WANO recommendation

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Regulatory Environment (1)?

• Standards hierarchy
• NII SAPS
• IAEA standards
• IEC standards
• IEC 61226
• PSA based assessment
• Target 10-7 / year
• Limit of reliability claims for software based
  systems
• Assume 1 demand / year
• 10-4/demand
• Require diverse protection to make up 10-3/demand

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Regulatory Environment (2)?

• Application to Sizewell B
• Primary Protection System
• Four channels, 2 out of 4 tripping
• Software based
• Production excellence
• IEC 61880
• Independent confidence building
• Extensive testing
• Independent code safety assessment
• Secondary Protection System
• Four channels, 2 out of 4 tripping
• Protection for frequent faults
• Laddic magnetic amplifiers
• Diverse technology

22
Regulatory Environment (3)?

• New build
• In general, same regulatory requirements as
  Sizewell B
• Diversity requirements in reactor protection
  systems
• Possibly lower protection system targets
• Passively safe systems will make fewer demands
• Commercial Off the Shelf systems
• Assessment of evidence
• Smart Instruments
• Regulator considering application to nuclear
  facilities
• Assessment of evidence

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Recommendations

• IAEA topics
• Estimating and extending life of IC equipment to
  address ageing and obsolescence
• Supporting the evaluation, acceptance and
  licensing of digital IC system
• Lessons learned from IC project implementation
  and guidance for modernisation and new plant
  project