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Copyright © 2015 by JSME
Proceedings of ICONE-23
23th International Conference on Nuclear Engineering
May 17-21, 2015, Chiba, Japan
ICONE23-1001
THE COMPONENT OPERATIONAL EXPERIENCE DEGRADATION AND AGEING
PROGRAM (CODAP): REVIEW AND LESSONS LEARNED (2011-2014)
Tudor Dragea
Student, University of Ontario Institute of
Technology (UOIT)
64 Baronial Court, M1C 3J7
Toronto, Ontario, Canada
Phone: (416)-846-3975
tudor_dragea@rogers.com
Dr. Jovica R. Riznic,
PhD, P.Eng., FASME
Canadian Nuclear Safety Commission
(CNSC), American Society of Mechanical
Engineers (ASME)
280 Slater Street, K1P 5S9
Ottawa, Ontario, Canada
Phone: (613)-943-0132
jovica.riznic@cnsc-ccsn.gc.ca
Keywords: OPEX, CODAP, NEA, Ageing, Degradation.
ABSTRACT
The structural integrity of piping systems is crucial to
continuous and safe operation of nuclear power plants.
Across all designs, the pressure boundary and its related
piping and components, form one of the many levels of
defense in the continuous and safe operation of a nuclear
power plant. It is therefore necessary to identify, understand,
evaluate and catalogue all of the various degradation
mechanisms and failures that affect various piping systems
and components across all nuclear power plants (NPP’s).
This need was first recognized in 1994 by the Swedish
Nuclear Power Inspectorate (SKI) which launched a five-year
Research & Development (R&D) project to explore the
viability of creating an international pipe failure database
(SKI-PIPE) (Riznic, 2007). The project was considered to
be very successful and in 2002, the Organization for
Economic Co-operation and Development (OECD) Pipe
Failure Data Exchange (OPDE) was created. OPDE was
operated under the umbrella of the OECD Nuclear Energy
Agency (NEA) and was created in order to produce an
international database on the piping service experience
applicable to commercial nuclear power plants. After the
successful completion of OPDE, the OECD, as well as other
international members, agreed to participate in OPDE’s
successor: the Component Operational Experience
Degradation and Ageing Program (CODAP).
The objective of CODAP is to collect information on all
possible events related to the failure and degradation of
passive metallic components in NPP’s. With CODAP
winding down to the completion of its first phase in
December 2014, this report will focus on the conclusions and
the lessons learned throughout the many years of CODAP’s
implementation. There are currently 14 countries
participating in CODAP, many of whom are industry leaders
(France, Canada, U.S.A., Germany, Japan, Korea etc.). This
cooperation on an international scale provides a library of
OPerational EXperience (OPEX) for all participating NPP’s
(Lydell et. al., 2008). CODAP also allows for the sharing of
valuable information on a wide range of reactor types such as
Pressurized Heavy Water Reactors (PHWR), Pressurized
Water Reactors (PWR) and Boiling Water Reactors (BWR).
The use of CODAP/OPEX and knowledge databases can
and have resulted in a number of significant inspection
changes at NPP’s worldwide. For example, Canada has

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already utilized CODAP to address thermal stratification and
piping material fatigue issues. Korea has collected and used
information for piping failure events to identify sites of
potential concern in their in-service inspection programs.
Currently there are over 4500 recorded events on pipe
failures affecting all ASME Code Classes and non-safety
related piping. These events encompass all known modes of
damage/degradation and their respective failure modes.
1. INTRODUCTION
The CODAP event database is an online database that is
owned and operated by the NEA and member countries. The
purpose of this report is to highlight and summarize the
wealth of information stored within CODAP, as well as, the
future applications of it. The uniqueness of the project has
allowed for the sharing of vast amounts of information across
all reactor types and designs and has led to significant
increase in overall awareness of the damage/degradation
mechanisms that affect various piping systems and how to
properly manage/maintain their ageing effects. Currently the
13 nations participating in CODAP are: Canada, Chinese
Taipei (Taiwan), The Czech Republic, Finland, France,
Germany, The Republic of Korea, Japan, The Slovak
Republic, Spain, Sweden, Switzerland and the United States
of America. Table 1 summarizes the number of events
entered into CODAP by member countries. There is also a
significant effort towards consulting and inviting other
countries to join the project.
Table 1 - CODAP EVENT ENTRIES BY MEMBER
COUNTRY (AS OF JULY 2014)
1.1 Scope of the CODAP Project
The CODAP project was established as an event and
knowledge database system. It collects information on the
degradation and failure of reactor primary systems, pressure
vessel internals, main process and standby safety systems (i.e.
ASME Code Class 1, 2 and 3 or equivalent) (ASME, 2009).
CODAP also allows for the collection of non-safety-related
(i.e. non-ASME Code) components with significant
operational impact. Future development of CODAP’s
successor will include information on age-related degradation
of buried tanks and piping.
What makes CODAP unique amongst other OPEX
databases is the “knowledge database” previously mentioned.
This additional feature allows for the collection of technical
information on components and degradation mechanisms,
applicable regulations, codes…etc. Due to this, CODAP
participants are able to benefit by:
 Acquiring additional information regarding operating
experience with piping components and systems, regulatory
practices, life-cycle management of ageing components and
existing technologies/equipment and personnel.
 Increased knowledge of ongoing degradation mechanisms,
mitigation strategies, regulatory concerns and approaches,
non-destructive examination (NDE) inspection
performance and results and any issues regarding NPP
operations, maintenance and return-to-service.
 Gaining an appreciation for emerging research and
development programs.
 Gaining additional knowledge on piping designs,
installation, emerging materials and operational issues.
Increased understanding concerning the current status of
piping reliability and life-cycle management at NPP’s
world-wide.
2. QUALITY ASSURANCE AND DATA QUALITY
The CODAP Quality Assurance Program (QAP) ensures
that the end product (the database with companion reports) is
of the highest quality. The QAP applies to all activities in the
project and is followed by all project participants.
For an event to considered for inclusion into CODAP, it
must undergo an initial screening for eligibility. This initial
screening goes beyond the abstracts of event reports to ensure
that only pipe degradation and failures according to the work
scope definition are included in the database. Riznic et al.,
(2014) discuss the work scope of CODAP project in further
detail.
The event is then processed for its “data quality” or
“fitness-for-use”. This is a characteristic of the process that
ensures that any given database record (including all of its
constituent elements, or database fields) can be traced to the
source information. The database records should contain
sufficient technical detail to support database applications. A
“Completeness Index” (CI) is assigned to each event in order
to identify the level of “data quality” of the information.
Table 2 outlines the CI definitions for all three categories of
completeness.
Count Country
2951 United States of America
364 Sweden
347 Germany
285 Japan
174 Canada
130 France
89 Switzerland
69 Korea (Republic of)
47 Finland
46 Spain
25 Czech Republic
8 Belgium
2 Slovak Republic

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Table 2 - CODAP COMPLETENESS INDEX (CI)
DEFINITIONS
CI Definition
1 Validated – all source data have been reviewed – no
further action is required
2 Validated – source data may be missing some
non-essential information – no further action
anticipated. The term “non-essential” implies that
information about piping layout (including location
of a flaw) may not be known exactly but can be
inferred based on other, similar events (at same or
similar plant)
3 Not validated – validation pending
The CI distribution across all events in CODAP is shown
in Figure 1. Ideally, the end goal is to have all events with a
Completeness Index of 1 however, the quality of the event
reports entered in CODAP are limited to the willingness and
capabilities of each NPP utility to provide such information.
Table 3 shows the CI distribution across all events for each
reactor type. Both the Pressurized Water Reactor (PWR) and
Boiling Water Reactor (BWR) designs have a significantly
higher amount of events across all CI’s which is directly
related to the sheer number of reactors in service
internationally than that of the Pressurized Heavy Water
Reactor (PHWR) design. Events can also be grouped in
accordance with their respective ASME Code Class (ASME,
2009).
3. DATABASE CONTENT
As of 2014, the number of reports that have been approved
into CODAP is 4547. This number increases daily as more
and more reports get approved and entered into the database.
Figure 2 depicts the number of events as they occurred per
calendar year. The low number of events during the 1970’s is
due to the low number of plants which had been
commissioned during the time. Subsequently, the increased
numbers of events during the 1980’s and onward are
indicative of the increased number of plants that were put into
service during that time, with the outliers in the early 1980’s
are mainly due to the stress corrosion cracking issues that
were discovered in BWR plants.
At the turn of the millennium, the apparent decrease in
events is a combined result of a heightened awareness and
concern of various degradation mechanisms that affect all
NPP’s, as well as an overall decrease in total NPP’s
operational (Riznic, 2007). Figure 3 depicts the component
age at time of failure for CODAP events up until July 2014.
The data suggests that component failure is more likely at a
younger component age, with the most extreme outlier
occurring across the 10-12.5 year range. However, it should
be noted that this data incorporates all of the historical entries
in CODAP and includes events from reactors that are no
longer in operation. Therefore, the number of components in
the CODAP database is not always representative of the ones
that are currently in service in NPP’s.
Figure 2 - CODAP EVENT CI
DISTRIBUTION
Table 3 - CODAP COMPLETENESS
INDEX PER REACTOR DESIGN
Figure 1 - COMPONENT DEGRADATION AND
FAILURE BY CALENDAR YEAR

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The large number of events and associated data that are in
CODAP, allows users to analyze component degradations
and failures across various related fields of interest. Figure 4
illustrates the distribution of these events across all three
reactor types. It should be noted that the number of events is
proportional to the number of reactors in service in each
member country as well as, the data availability of
information and affiliation with predecessor databases such as
OPDE and SCAP-SCC.
CODAP utilizes a roll down menu that allows for
consistent data input throughout the majority of the data entry
boxes. This is very useful for the quick querying of damage
and degradation mechanisms while limiting the amount of
possible search results. The list of damage and degradation
mechanisms can be further grouped together to increase the
population of data per mechanism. This feature is very useful
when trying to see how the apparent causes are linked to
certain attributes like piping material, weld material, weld
location, pipe size…etc. Figure 5 highlights the number of
events that relate to each type of know degradation
mechanism for piping components specifically for the
PHWR.
Figure 6 illustrates the number of events that relate to each
piping diameter size across all three reactor types. The lack of
non-piping events for the PHWR in comparison to other
reactor types can likely be attributed to the much smaller fleet
of operational PHWR units compared to the other two, and/or
due to the significant increased number of piping components
that are part of the PHWR design. Canada is also the only
country with operating PHWR’s that is uploading PHWR
events in CODAP.
Figure 3 - COMPONENT FAILURE AS A FUNCTION OF
IN-SERVICE TIME
Figure 4 - NUMBER OF EVENTS BASED ON
REACTOR TYPE
Figure 5 - CODAP EVENT TYPE FOR PHWR
Figure 6 - CODAP EVENT DISTRIBUTION BY
DIAMETER CLASS AND REACTOR TYPE

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4. DATABASE APPLICATIONS
The CODAP database has numerous applications which
have been identified by the NEA (NEA, 2014). There have
been many publications and conferences which have provided
a great deal of topics on CODAP and its applicability to the
analysis of material degradation, code development,
Probabilistic Safety Assessment (PSA), risk-informed
regulation and general plant safety. There have also been a
significant number of papers and presentations give on the
applications of the OPDE database (CODAP’s predecessor).
Since CODAP is an evolution of OPDE and shares almost all
of the same event entries, it is quite reasonable to assume that
any applications of the OPDE database can be directly shared
with CODAP.
Numerous member countries and their respective utilities
have been able to utilize CODAP, as well as OPDE,
alongside additional proprietary databases for insight into
many fields:
 Pipe failure rates;
 Piping rupture and damage frequencies;
 Component reliability parameters;
 Crack population size and distribution;
 Leak-before-break case studies;
It is important to stress the limitations of statistical analysis
for the above applications. The results of statistical analysis
based on the querying from an event database like CODAP
are dependent on the results from the query and verification
of applicability of the returned events. The CODAP database
covers a wide range of NPP’s designed as early as the 1960’s
to the current Generation III reactors from the 1980’s.
Therefore, a major concern is raised on how to utilize and
compare data from these technologies that span across a
period of over three decades. The grouping of events will
have a direct impact on the statistical values that the analysis
arrives at.
Recently, Yuan et al., (2009) proposed a method that takes
into account the “learning curve” the nuclear industry
experiences over that period. Yuan et al., (2009) proposed a
nonhomogeneous Poisson process model for describing the
piping failure events. Their method takes into account plant
age (interval of time between first reactor criticality and first
pipe failure), and the Cohort Effect (NPP’s built at different
points in time employ different levels of technology).
Inclusion of the Cohort Effect allows the calculation to be
representative of the plant technology, design and material.
This in turn allows the model to be more versatile when used
to analyze any other stochastic event data. Yuan et al
showed that when the Cohort Effect (Learning Curve) is not
considered in calculating failure frequency, the end result is
largely overestimated (Yuan et. al, 2009). Therefore it is
important to have a baseline to compare data from such a
diverse database like CODAP.
As a result, expert elicitation is an essential component to
the process. From that point, it is extremely important to have
a database such as CODAP so that experts can support their
assessments. Since an event database includes information on
historical events, the completeness of the event population in
the database always is an important factor in determining its
“fitness-for-use”. Completeness is an indication of whether or
not all the data necessary to meet current and future analysis
demands are available within the database. There are two
types of metrics that have to be considered in quantitative
piping reliability analysis: 1) failure rate, and (2) conditional
failure probability. CODAP allows for support of failure rate
estimations due to its inclusion of extensive piping system
design information that yields information on the total piping
component population that has produced the failure
observations (Riznic, 2007).
The CODAP database has been, and continues to be
utilized by member countries all over the globe to estimate
initiating event frequencies and risk-impact evaluations for
application and system specific piping components.
These estimations and evaluations have been used to
calculate:
 Internal flooding initiating event frequencies:
 High energy line break (HELB) frequencies:
 Loss-of-Coolant-Accident (LOCA) frequencies:
 RI-ISI risk impact evaluations and ageing
management analysis of specific systems (Yuan, 2009)
The NEA have prepared a CODAP topical report (NEA,
2014) which evaluates the effects of Flow Accelerated
Corrosion (FAC) on carbon steel and low alloy steel piping.
The report outlines the significance of FAC across all reactor
types and how CODAP can be used to assist in the
development of FAC management programs.
FAC is a chemical affect that is primarily influenced by pH,
hydrodynamics, oxygen content and temperature. Geometric
aspects of piping systems and layout also play a key role in
its occurrence. FAC has caused sudden ruptures
(break-before-leak, BBL) in high and moderate energy piping
systems, resulting in plant transients and affecting safety/non
safety related equipment by leaking steam and water
(spatial effects).
The FAC event data collected by CODAP supports the full
range of probabilistic evaluations of piping reliability (NEA,
2014). The event population and exposure term data provide
input to pipe failure rate and rupture frequency calculations.
Table B2 illustrates some of the results and associated
statistical estimations as a result of detailed queries that were
done in CODAP with respect to FAC.
5. DATABASE ACCESS
CODAP is a restricted database and its access is limited to
participating organizations that provide input data. Since the
data inputted into CODAP is proprietary by nature, events
and associated reports/information are managed by respective
national coordinators.
6. CONCLUSIONS
With the CODAP project nearing the end of its first phase
in December 2014, it is now appropriate to analyze the
lessons learned from CODAP in order to ensure that its
successor is a significant improvement and evolution of the
database. Continuous international effort and participation is
essential for the success of CODAP and its successor.
Additional efforts should be made in order to expand the

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current number of member countries in the hopes of
expanding the knowledge base within the database.
The CODAP project can be considered a success and has
received a considerable amount of international interest.
Although the project is nearing the end of runtime, we are
looking forward to continue with the next phase. Data from
the database has already been used for practical applications
on nuclear power plants in support of risk-informed
in-service inspections (RI-ISI) or for estimating pipe-rupture
frequencies from piping defects (NEA, 2005). Projects such
as CODAP provide excellent framework for the growth and
improvement of the nuclear industry and act as stepping
stones for multilateral cooperation on new research and
information sharing projects. Information from the project
provides a knowledge tool for research that assists nuclear
regulatory staff with their day-to-day work.
CODAP provides an effective tool and technical basis in
support of the development of such items as RI-ISI for
utilities, PSA initiating event frequencies associated with
piping system failures, probabilistic fracture mechanics
(PFM), degradation mechanism evaluation.
Leak-Before-Break (LBB) analysis, and ageing management
programs (AMP). All of which are necessary in maintaining
the safety of NPP’s worldwide.
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CODE, SECTION XI – RULES FOR INSERVICE
INSPECTION OF NUCLEAR POWER PLANT
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EDITION”, American Society of Mechanical
Engineers, New York (NY), USA.
[2] Ballestros, A., Negri, P., Peinador, M., Sanda, R.,
Wenke, R., Zerger, B., 2014, “Analysis of events
related to cracks and leaks in the reactor coolant
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