Ageing management, component replacement and re-commissioning against the original licensing basis
Commissioning software for plant life extension where replaced and refurbished components have to be re-commissioned without disturbing the licensing basis of everything around them.
Extending a reactor's operating life means replacing steam generators, reactor vessel internals, cabling and I&C systems that are approaching the end of their qualified life, each swap re-commissioned against the plant's original licensing basis rather than treated as a green-field install. Deskely holds the ageing management assessment, the replacement scope and the re-commissioning record in one register, so the extension case is built from evidence rather than assembled after the outage closes.
- Assets
- Replaced SGs, RPV internals, cabling, I&C
- Test
- Re-commissioning, functional retest, baseline comparison
- Basis
- Original licensing basis and ageing management
- Gate
- Long-term operation (LTO) authorisation
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The problem
A life extension outage touches systems installed decades apart, and the original commissioning record is rarely in a form anyone can search.
A long-term operation programme replaces major components — steam generators, reactor coolant pump seals, control rod drive mechanisms, obsolete I&C cabinets — against original design documents that may predate digital record-keeping entirely, alongside ageing management inspections on components staying in service.
When the original commissioning baseline exists only as scanned paper and the replacement scope's test records live in a separate modern system, nobody can quickly demonstrate that a replaced component's new commissioning record actually matches or improves on the licensing basis it is replacing.
Deskely links the original as-built baseline, the ageing management assessment and the new component's re-commissioning record against one tag, so the licensing basis comparison an extension case requires is a query, not a research project.
Setting up the register
Replaced components and their baselines are tagged assets carrying both the original design basis and the new evidence.
Original design documents, historic commissioning records and current ageing management assessments are parsed and attached to the same tag as the component being replaced, so the licensing basis a replacement has to meet is visible before a single new test is run.
Replacement scope — new steam generators, refurbished valves, new cabling routes — is modelled with its own re-commissioning ITP, referencing the original functional requirements rather than a generic new-build template that would miss plant-specific operating history.
Ageing management inspection findings on components that are not being replaced are held in the same register, so a life extension safety case can present replaced and retained scope from one consistent evidence base.
Execution
Re-commissioning and functional retest prove the replacement matches or exceeds the system it replaced.
Replaced components are functionally retested against the original acceptance criteria first, then against any updated criteria driven by a design improvement, with both results recorded so the comparison is explicit rather than assumed.
System-level retest after a major component swap — such as full-power ascension testing after a steam generator replacement — is captured with the same rigour as new-build hot functional testing, because the interfacing systems have aged even where the component itself is new.
Findings that reveal an ageing issue in an adjacent, non-replaced system during retest are logged as their own finding, feeding back into the ageing management programme rather than being closed out as an isolated commissioning punch item.
LTO authorisation and updated baseline
Long-term operation is authorised from a documented comparison, not an assumption that new equipment is automatically compliant.
The long-term operation submission draws on the linked baseline and re-commissioning records for every replaced system, giving the regulator a direct comparison between what was licensed originally and what is now in service.
The plant's configuration baseline is updated at the tag level once re-commissioning closes, so the next outage's planning starts from the current as-built condition instead of a baseline that is still describing equipment removed years earlier.
Every re-commissioning signature carries a name, role and timestamp, tied back to the original design basis it was tested against, which is the traceability an extension case and its independent review are built to test.
Re-qualifying an operating plant without breaching its licence conditions
A life extension outage is executed inside a plant that is still licensed to operate, so every replacement has to be proven without ever putting the existing licence conditions at risk.
Replacing a steam generator or RPV internal component happens inside a plant whose licence conditions remain in force throughout the outage, meaning technical specification limiting conditions for operation, surveillance intervals and the existing safety case for untouched systems all still apply while the replacement scope is under way, and a replacement activity that inadvertently breaches one of them is a licence condition non-compliance, not a schedule slip.
Cold and hot functional retest after a major replacement has to be reconciled against 10 CFR 50 Appendix B (or the equivalent national QA programme) requirements for the plant's existing design control and corrective action programme, because the replacement is a design change to an operating facility, not a new build where the QA programme is being established from zero.
Deskely flags every replacement activity against the specific licence conditions and technical specification limits it touches, so the outage team can see before the first bolt is loosened which limiting conditions for operation constrain the work window, rather than discovering the constraint mid-outage when a surveillance interval is about to lapse.
The long-term operation evidence set
Six record types support the case that an ageing plant still meets its original licensing basis after component replacement and re-commissioning.
Life extension work re-proves an operating plant against the same licensing basis it was built to, decades on, with ageing components replaced or requalified along the way. These records are what an LTO authorisation submission actually cites, not a generic outage report.
Ageing management assessment record
That a specific structure, system or component's condition and remaining life have been assessed against its ageing mechanism ahead of the LTO period.
Compiled during the LTO scoping phase, before replacement scope is fixed.
Component replacement traceability record
That a replaced component's new material certification, installation record and post-installation test tie back to the original design basis it is required to meet.
Produced as each replacement is installed and re-commissioned.
Re-baseline configuration record
That the plant's configuration baseline has been updated to reflect replaced components and any associated design changes, so future work references the current, not the original, baseline.
Updated once replacement and re-commissioning scope closes.
Post-modification functional test record
That a system containing replaced or upgraded components still meets its original functional and safety performance requirements after the work.
Executed before the system is returned to service post-modification.
Licence condition compliance cross-reference
That replacement and re-baseline work has been checked against each relevant licence condition, with no unintended breach introduced by the LTO scope.
Assembled ahead of the LTO authorisation submission.
Periodic safety review input package
That ageing management, replacement and re-commissioning evidence collectively supports the periodic safety review's conclusion on continued safe operation.
Compiled to feed the periodic safety review cycle.
How it runs
From ageing management assessment to LTO authorisation.
Life extension programmes reward linking the old record to the new one before a single bolt is turned, because the extension case is a comparison, and a comparison needs both sides in the same place.
- 01
Recover the original baseline
Historic design documents and commissioning records parsed and attached to the tag of the component being replaced.
- 02
Scope the replacement
New components modelled with re-commissioning ITPs referencing original functional requirements, not a generic template.
- 03
Retest against both criteria
Functional retest results captured against original and any updated acceptance criteria, side by side.
- 04
Update the configuration baseline
As-built condition refreshed at the tag level on re-commissioning closure, ready for the next outage and the LTO submission.
FAQ
Questions about Plant life extension scopes.
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