This document provides an overview of aging management experience and the status of the IVMR Project. It discusses: 1) The importance of proper scoping and screening as the basic step for aging management and long-term operation (LTO) of nuclear power plants. 2) The results of aging management reviews (AMR), including the identification of new degradation mechanisms and validation of time-limited aging analyses. 3) Updates on experimental work being done as part of the IVMR Project to study core melt progression and heat flux in a reactor pressure vessel, including results from small-scale and plans for large-scale testing facilities.

1. 1
Aging Management Experience
Status of the IVMR Project
J.Zdarek
ATOM FORUM
June 2017

2. 2
Overview
1) Scoping and Screening for LTO and AM
2) Passive and Active Component Approach
3) AMR and the most important results
4) Irradiation Swelling Effect
6) DM Fatigue and TLAA
7) New PTS Assessment
8) Preventive Maintenance Programme
9) IVMR Project Update

3. 3
Proper scoping and screening as the
basic step for AM and LTO
One of most important Regulatory Body requirement for the
operational permission after planned period of operation
(requirement for LTO operation) is :
The NPP must demonstrate, that requested level of safety
is maintained during the whole period of LTO for SC
critical from safety and economic point of view
This means to set up proper aging management
including proper maintenance and to be able to
show/prove/demonstrate it, to everybody who wants to
know - who has the right to know
3

4. 4
Proper scoping and screening as the
basic step for AM and LTO
Conclusion:
For safe and effective LTO operation must be ---
implemented proper Aging management (with help of
tool called Aging Management Review) for passive
components
- - implemented an effective Maintenance program based
upon SCs efficiency and condition monitoring for active
components
- implemented for SCs in the scope of LTO

5. 5
AMR gives following answers:
 What are degradation mechanisms (DM) or aging effects
(AE) influencing requested functions?
 What aging management programs (AMP) and
processes are used to cover identified DM and AE?
 Are those AMPs sufficient? That is:
 are all DM and AE controlled by AMPs?
 are DM and AE controlled properly?
 Are all TLAA (Time Limiting Aging Analysis) valid for
requested period?
If there is any insufficiency the corrective activities must
by defined and performed!

6. 6
Information in Catalogue of Degradation
Mechanisms and Aging Effects
NPP SCs divided into About 600 commodity groups comprising
more than 50000 structures and components
Catalogue connected with main NPPs SSCs database, contains
following type of information:
Material
Risk priority number of the material according to EPRI
assessment methodology from Material Management Matrix
Project (and others parameters)
medium type, medium parameters,
environment , environment parameters,
Degradation mechanisms and Aging Effects (Identified during
operation, controlled, potential according to world experience)
Tool used by NPP specialists to optimize
aging management and maintenance process

7. 7
Newly identified DM at NPP ETE
(VVER 1000)
During performed AMR the possibility of the new
DM was identified – irradiation swelling due to
combined influence of temperature and neutron
flux (reactor internals)
On the basis of experience from others NPP and new state of
art of know how
The following remedial activity was
suggested by team of evaluators:
Computational verification of the DM
swelling development during design
operation and supposed LTO period

8. 8
Core Baffle – the most sensitive component
of internals to the swelling
Core baffle

9. 9
Measurement of Core Baffle
The measurement principle
Measurement of dimensions at specific
locations (areas near threaded rod and the
middle segment).
Rotation 2x 60 ° provides a measurement
of the entire periphery of the ring.
Measuring dimension core baffle at
selected height levels - each ring will be
measured at two levels (proposal about
200 mm from the top and 200 mm from the
bottom edge of each ring).
This process of measurement corresponds
to the control measurements carried out
under the control of the assembly.
9

10. 10
Measurement of Core Baffle – Design Model
Drawing device for measuring the core baffle dimensions.

11. 11
Swelling degradation – present status
in the Czech Republic
The swelling was accepted as DM influencing
lifetime of internals
Design of the measurement device was agreed with NPP
Design phase is ongoing
The necessary hardware material is being purchased
The development of state of art in the field is continuously
monitored
Methodology for swelling evaluation is developed with aim to
introduce it into Czech Technical Normative Documentation

12. 12
DM Fatigue and TLAA (time limiting aging analysis)
One of the important result of the AMR performed (in
Dukovany NPP) is an identification of the existing TLAAs
and information about their validity
Some fatigue TLAA were not valid for planned
period of LTO
Some of them were out dated
As a consequence extensive
program of TLAA revalidation
was started

13. 13
Example - Revalidation of Fatigue
TLAA of RPV
Reactor pressure vessel is complicated
components, for revalidation of the TLAA it was
divided into several parts that were evaluated
separately (from fatigue point of view)
Nozzles and their flanges of the RPV head: TK-EV, HRK
Main flange
Barrel part the RPV
Main nozzles of the RPV
Platform for fixation of the RPV internals

14. 14
1
4
Input parameters for TLAA revalidation -
original drawings

15. 15
Measurement on RPV
necessary geometric details received by precise
measurement on manufactured RPV in Škoda JS
Co.
Chief of the computational
team RNDr. V. Pistora

16. 16
Laser scanning of RPV head (HRK nozzle flange) – measured
in the International Paks Training Centrum

17. 17
Benefits of new Assessments
Lifetime and Integrity Assessments
corresponding to the LTO requirements were
elaborated
Fatigue TLAA of RPV for 40 years of operation
Identification of critical point from fatigue point of
view
Preparation of remedial action to ensure lifetime
60 years
Modification of ISI
Modification of maintenance procedures*
Modification of CSAMP Pressure vessel
Sources for updating of related technical
documentation
Modification of the AMP Monitoring of Low
Cycle Fatigue
* Procedure for the tightening of the main
flange screws to minimize fatigue

18. 18
Important changes in new IAEA VERLIFE
methodology with respect to the older VERLIFE
2008 (PTS chapters)
18
1. Residual stresses are included for normal
operational condition and heat affected zone
2. Alternative [KIC] curve (according to RF code MRKR-
SCHR-2004)
3. Warm Pre-stressing approach is accepted even for
non – monotonic unloading
4. New definition of residual stresses (according to
MRKR-SCHR-2004)
All above changes are taken into account in a new evaluations

19. 19
Preventive maintenance programme
Fully performed by NPP team
For LTO purposes the existing preventive maintenance programme
which has been elaborated in agreement with the Asset
Management was reviewed with respect to:
Equipment categorization (its importance for safety and economy)
Legislative requirements (In service inspection plan (ISI), legislative
requirements, revision rules)
Recommendations of manufacturers
Our experience with equipment operation
Adopted external good practice (maintenance templates: EPRI Preventive
maintenance database)
This programme is continuously updated with respect to the results from
its performance monitoring (Health reports) and from the feedback, with
respect to the experience from the international practice and to the
requirements arising from the changes in legislation.

20. 20
Preventive Maintenance of RPVs
Preventive maintenance:
Activities under in-service inspection (on the RPV by In-service Inspection
Program)
Activities defined by the limits and conditions
Activities defined by the work procedures
(for assembly and disassembly of the reactor)
Activities implemented during the maintenance:
Lubrication
Cleaning work
Inspections and seals replacement
Inspections and repair of flanged joints
Part of RPV
with implemented PM

21. 21
Findings dicovered during PM
Frequent findings discovered during PM on RPVs at NPP
Temelin:
The incursion of foreign materials into the reactor vessel.
Leaks
Impurity, scratches, nicks, pressure marks/damage
Conclusion from findings in the PM:
Optimization of working procedures
Change in technology, material change of damaged parts
Increased volume of inspections of risk areas
Revision of control documentation

22. 22
Update on the IVMR Project
Calculation performed within WP 2.5 of the HORIZON IVMR
project are consistent with the initial results from Kurchatov
Institute
All calculations (UJV MELCOR, IVS ASTEC, KI SOCRAT) give
comparable maximum heat flux at steady state with value around
1.4 MW/m2
The position of this maximum differs: around 1m above the
bottom of the RPV in the UJV calculation and around 1.5 m above
bottom for KI and IVS calculation
In UJV calculation with MELCOR, there is also a transient
situation where whole profile is shifted towards higher values,
even at the bottom. In this case, the maximum heat flux is
between 1.8 and 2 MW/m2

23. 23
Update on the IVMR Project
If we are confident in those results, the large
scale experimental facility the THS-15 under
construction at UJV Rez should be able to
deliver a heat flux of 1.4 MW/m2 at various
locations between 1m and 1.5 m above the
bottom of the RPV. It should also be able to
deliver a peak heat flux of at least 1.8 MW/m2
near 1 m above the bottom of the RPV, which
is the top of the oxide pool

24. 24
Comparison of Kurchatov Institute results
with small scale results
2
4

25. 25
THS – 15 Large scale facility
Cooling channel heating segments
2
5

26. 26
Heater segments holes
2
6

27. 27
Latest technology on site - Condenser
2
7

28. 28
New analytical calculation results from KI
2
8
Maximum heat flux value was obtained using three-
layer model. Predicted value is ~1.9 MW/m2 by HEFEST-
ULR code and ~2.4 MW/m2 by ASTEC code. Difference
between calculation results is ~20-25%. Such
difference of results could be caused by RPV
discretization. IVMR studies require very detailed RPV
grid. Mesh density used for ASTEC code is probably
not-enough for IVR task, but it is one of the code
limitations. Poor mesh provides incorrect calculations
of gradient functions and thermal resistance, which are
significant for heatflux definition.

29. 29
Confirmation of the THS-15 capabilities
2
9
Large scale facility THS-15 is build with significant
margin to the recommended HF values along the whole
height of the cooling channel:
- In the lowest part of the semieliptical lower head we
consider to reach value about 1.9MW/m2
- Within remaining critical height of the cooling
channel we consider to reach values 2.2 – 2.4 MW/m2
Those estimations are already shown on previous
slides

30. 30
Small scale results
3
0
Smal scale experiment results (over 120
already performed), with special surface
modification provides very significant
margin in the HF with respect to predicted
values of the HF based on HORIZON IVMR
Mgm recomenndation.
Comparison is already seen on previous
slides

31. 31
Conclusion
3
1
Small scale experimental results are providing very
positive results with respect to possible safety margin
to the CHF
Lessons learned from small scale experiments and
technology is very valuable for the large scale facility
design and operation
Large scale facility is under construction.
Present estimation of HF values as recommended by
serious analytical work within the WP 2.5 IVMR
HORIZON Project will be met.

32. 32
Thank you for your attention