LESSONS LEARNED FROM AGING MANAGEMENT ACTIVITIES MODERNISATION OF THE WWER 440 UNITS CONSIDERING ASP

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LESSONS LEARNED FROM AGING MANAGEMENT
ACTIVITIESMODERNISATION OF THE WWER 440 UNITS
CONSIDERING ASPECTS OF THE LTOJ.ZDAREK,
P.KADECKA
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SUMMARY

• Existing NPPs are secure source of energy. Their
  Long Term Operation is strategic goal for any
  utility. The US License Renewal process is
  closely followed by the IAEA activity and WWER
  operating countries. Recent lessons learned from
  several Aging Management Programmes (US, IAEA,
  WWER) will be summarized.

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INTEGRATED PLANT REVIEW
Scope
Screen
Aging Mgmt. Review
Passive or Active?

• Systems, components,
• and structures within
• the scope of
• 10CFR54
• Safety-Related
• Non-Safety Related
• that could prevent
• safety function
• Regulated Events
• SBO, EQ, Fire,
• PTS, ATWS
• SCOPE

Passive
Periodically Replaced?
No
Active
Managed by existing activities?
Aging Management Review
No
Yes
Modify existing or add new programs
Yes
Structures Components not subject to Additional
Aging Management Review
Demonstration that the effects of aging are
adequately managed
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12 DETAILED AGING ANALYSIS
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THE LTO DATABASE

• Together 6000 SSCs divided to 60 LTO groups
• It is not possible to provide assessment for all
  selected 6000 SSCs
• Based on engineering judgement and operation
  experience 215 type groups defined
• For the type groups detailed assessment and
  conclusions prepared

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KEY RECOMMENDATIONS FROM THE NPP

• For the type groups where replacement of the SSCs
  is standard practice without large cost is
  proposed to cancel them from the LTO database.
  About 25 out of 215 type groups.
• In the assessment to account for existing changes
  of material, including all means to prevent
  different damage mechanisms e.g. corrosion

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FIRST SET OF REQUIREMENTS FROM THE NPP

• To assure enough spare parts or new components in
  case that regular replacement is possible
• In all high damage exposed places to accomplish
  material replacement with higher damage
  resistance
• On all components with higher degradation
  occurrence to increase maintenance and testing
  requirements

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LIST OF PROGRAMMESWITH INPUT TO MODERNISATION

• DB Collation
• Equipment Qualification
• PTS/WPS
• P/T curves
• Civil structures

• SG monitoring
• Sealing Programme
• UT/EC Qualification
• RI ISI
• Cable monitoring

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DB COLLATION

• Detail knowledge of the DB Requirements and DB
  Parameters will assure correct modernization
  programme
• The configuration management programme requires
  to have DB data
• The License Renewal for the LTO also requires the
  DB Collation

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EQ

• Qualification status for about 2200 equipment
  per unit within EQ list is established
• All equipment from the EQ list is classified in
  following categories
• Qualified
• Qualified if specified conditions are fulfilled
• Non qualified
• Modernization Programme has to assure qualified
  categories within EQ list as principle
  requirement for the LTO

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PRIMARY SIDE FAILURES DOMINATE PTS RISK We need
PTS conclusion for WWER. Presented conclusion is
for US PWRs.

• Primary side failures dominate
• Low embrittlement
• stuck open valves that
• later re-close
• Higher embrittlement
• medium large diameter
• pipe breaks
• Secondary
• main steam line breaks
• stuck open valves
• of much smaller consequence,
• only at extremely high embrittlement levels

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P-T CURVES

• 2 types of p-T curves created for NPP Dukovany
• for constant temperature (serving for protection
  against low-temperature-over- pressurisation)
• for step cool down (serving for protection
  against PTS)
• Westinghouse methodology applied
• New set of p-T curves generated in 2005 for
  underclad cracks with depth 15 mm

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CIVIL STRUCTURES

• Ageing management programme and monitoring shall
  be applied on the following components of NPP
  structures
• soil structure interaction
• design, construction and performance of
• basemat
• vertical concrete constructions (shrinkage,
  creep)
• ceilings
• roofs
• ways
• operation mode of NPP
• preventive and corrective maintenance
• influence of components modernization

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SG MONITORING

• On-line / periodical
• Chemistry of feed water, blow down
• During shut down
• HOR (Hide out return) MULTEQ pH in crevices
• Outage
• NDT (Visual control, Eddy current.)
• Analyses of removed deposits, withdrawn tubes
• Statistical evaluation of new damage indications

• Database of chemical regimes and tube damage

Electrochemical Evaluation System
on-line information on crevice status ?
on-line solution sampling from crevice ?
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SEALING PROGRAMME

• complex approach to seal assessment
• serrated profile gaskets with pure-graphite
  facing MITesHT
• applications main circulation pump, steam
  generator
• replace of nickel seals
• low level of stress for leakage rate class
• low torque
• verification of seal parameters
• great numbers of seal renovation

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UT/EC QUALIFICATION

• NDT Qualification focused on UT/ET qualification
  of equipment, inspection procedures (IP) and
  additional personnel qualification
• UT/ET qualification has to be completed for
  majority of inspection areas in 2006 (incl. PHARE
  ISI 2002)
• In all above aspects Qualified inspections of
  Safety Significant and Safety Related inspection
  areas required
• for extended inspection intervals
• as principle requirement for the LTO
• Missing
• additional personnel qualification (especially by
  blind tests)
• verification and evidence by computer modelling
  (CIVA simulations) for early completed UT/ET
  qualifications
• verification on realistic type defects for some
  qualifications

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RI ISI

• Current Status Verification of selected RI ISI
  approach/EPRI methodology for WWER type plants
  based on the following pilot studies
• LP ECCS at Temelin NPP (ETE)
• Primary piping including pressuriser piping for
  Dukovany NPP
• Steam and feed water piping (as High Energy
  piping) at ETE
• Participation in a worldwide benchmark of RI ISI
  methodologies and verification on at least 4
  selected systems at Ringhals NPP in 2006-2007
  (RISMET)
• Transition to commercial RI ISI applications
  after completion of RISMET project and in case of
  approval by SUJB as a requirement for the LTO
• Verification of other risk/RI-ISI approaches BER
  RI ISI, Streamlined RI ISI, RI Repair/Replacement

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CABLE MONITORING

• Systematic cable ageing management programme is
  needed at all NPPs based on cable deposits,
  environmental monitoring, cable ageing monitoring
  and software system for cable life assessment.
• Replacement of degraded cables.
• Relocation of cables to avoid hot spots.
• Modify environment to reduce severe conditions.