Obsolescence Management of Station Control Computers at ... - IAEA

Obsolescence Management of Station
Control Computers at
NPP CERNAVODA UNIT 1:
Dragos Popa-Nemoiu,
CNE Cernavoda Romania
Digital Systems Superintendent

Unit 1 initial obsolescence work -
Peripheral replacements
Replace old printers with laser
printers
Replace CRT monitors with LCD
monitors
Replace console with PC
Add gateway for Data Acquisition
Functions

Unit 1 SSCI 125 design deficiencies
and work around to mitigate effects
Real Time Clock delays – build RTC Booster
to correct RTC
Scanner uncertainty – provide external
monitor for timestamps
CPU overload – restructure programs to
reduce overload and provide resources for
software development
Map Registers corruption – mitigate effects
by special software
Frequent Memory Parity Error restarts – no
work around

Maintenance, Obsolescence and aging
management programs
Maintenance program – preservation
of current status
Health Monitoring Program – observe
and report degradation
Plant Life Management/Extention –
solutions for hole life cycle including
life extension

Choose replacement computer
Available for next 20-30 years
Guaranteed and proved reliability
Allow easy partial replacement in 30
days plant outage
Allow porting of control programs
without re-commissioning

COG (Candu Owners Group) Joint Poject
4048 – Sustained by all CANDU owners
Choose emulator solution
Reference computer is Cernavoda U2
SSCI 890 CPU is an V75 Emulator
Secure IP rights for COG
Resolve obsolescence of peripherals
Secure electronic components repository
based on Long Term Support
Build and qualify prototype for all Candu
computers refurbishments or new builds

Cernavoda U1 Refurbishment project
Based on COG PDCCZ
Project scope
-Order New CPU
-Order New Bulk Memory
-Order New Power Supply
Improvments
- High CPU speed
- More memory
-Eliminate obsolescence and
design weaknesses
-Increase reliability
Challenge
- Integrate new and old HW
-Build Executive which keep
complete SSCI 125 functionality
-Integrate applications with new
hardware and executive

Cernavoda U1 station computer
replacement strategy
Use COG Joint Project prototype as
reference
Use operation experience of U1 and
U2 to avoid non mature new design
Find solution for control software
porting to new computer
Develop integration strategy
Decide replacement and reduce risks

Design approach for Process Computer
replacement project
Control Programs
Real Time
Executive
Processor 50%
board
SSCI125
Peripheral
devices
Plant process
Compatibility of control
functions code with new
hardware
Rewrite of the Real Time
Executive to solve all
incompatibilities
There is no compatibility
to U1 SSCI125 or U2
SSCI890 Executive
Compatibility with
peripheral devices is
SSCI890 design key

Software Design strategy
1)Zero changes of control functions
2) Redesign of Real Time Executive to
keep functionality and accommodate
control functions in new CPU

Replacement project planing
The replacement activity supose 3 major
types of activities: replacement work,
hardware tests and software tests.
To minimize the total amount of time
required by those 3 activities during outage,
each of them has been analized and
solutions were find to optimize the process.

Test strategy
Multiple test environments
The hardware Test Deck
The PC based software emulator for
SSCI890
Unit 2 maintenance computer (DCCZ)
and new computer prototype (L3MAPPS)

Test Deck
Remove integration testing risk from outage(No time). Build an
exact replica of Unit 1 plant computers which could host
integration and testing work before plant outage. Use the
complete set of SSCI125 computers initialy purchased for Unit 2
and preserved as spares for Unit 1.Prepare for integration test
was the first refurbishment activitie. In a special site located in
Training Center all peripheral repalcement and software updates
made during Unit 1 operation years were also included in old Unit
2 computers. In the end was otbained an exact copy of Unit 1
computers, ready to start integration and testing of new
hardware.
There are 3 objectives related with this Test Deck:
- test and accomodate new hardware and eliminate any integration
incompatibility
- train hardware staff for replacement activities in plant and
minimize outage work
- test and integrate software (new Executive and Control Programs
of Unit 1)

Project Status
All test facilities mentionded before,
togheter with software development
and tests made in-house by plant
engineering staff, were all key steps
in preparing the plant for receiving
new replacement hardware.
The replacment in plant was executed
in 2010 Unit 1 Planned Outage.

January 2010
Work at Test Deck
started: demolition
of S3 panel

2 weeks later
SAT and software
testing may start

CONCLUSIONS
The replacement strategy deployed at CNE Cernavoda site
allow rehabilitation of 25 years old computers of Unit 1.
Following benefits were identified:
Allowed mimized implementation risks due to preservation
of field proven control software and multiple testing
configurations
Allowed achiving objectives with tenth of a complete
project costs by isolating only the hardware parts which
require software changes (being also the most obsolete
parts) and maximazing utilization of the plant staff
expertise.
Avoid any plant production loses by fitting all the
replacement work in a regular plant outage and moving
major tasks of integration and testing necessary for project
on a refurbished Test Deck.
The new simulation facilitie built for this project open new
ways for future development projects.

DCC Replacement Team : HW/SW Tehnic, Maintenance & Support

Thank You !