Metadata in Geological Disposal of Radioactive Waste:
The RepMet Initiative
1CIAMBRELLA, Massimo; 2 MCMAHON, Kevin; 3FEKETE, József I.

1Nuclear Energy Agency (NEA)
Radioactive Waste Management DivisionParis, France

2Sandia National Laboratories
Nuclear Waste Disposal Research and Analysis
Albuquerque, New Mexico USA

3Public Limited Company for Radioactive Waste Management
Budaörs, Hungary

Key words: repository, metadata, waste management

Abstract
The OECD Nuclear Energy Agency (NEA) launched the Radioactive Waste Repository Metadata
Management initiative (RepMet) in 2014 under the auspices of the Integration Group for the Safety Case
(IGSC) technical advisory body. RepMet’s goal is to recommend sets of metadata that can be used bynational radioactive waste repository programmes to manage their data, information and records thereof,in a way that is both harmonised internationally and suitable for long-term management and utilisation,e.g. in safety cases. Furthermore, the initiative that involves over ten different countries’ programmes
worked on the formulation of a consistent set of guiding principles for capturing and generating metadata,
recommending a shortlist of selected relevant standards and guidelines on international good practices.
National radioactive waste repository programmes require large amounts of data across multiple
disciplines (e.g. geoscience, radioactive waste management, engineering) that increase as these
programmes proceed in number, type and quality, for multiple reasons and goals (e.g. site characterisation,licensing, safety case elaboration). Considering these boundary constraints, the core idea of long-term
data management is that “data are being collected and managed for others to use them”. Next generationsof data-users have to be able to understand and access the information that the preserved data represent.
Individual scientists and research teams, as well as managers and communications specialists, need to beaware of this and document their work accordingly.
RepMet is facilitating their task by bringing about a better understanding of a key aspect of themodern data management within the field of radioactive waste disposal, namely the identification andmanagement of metadata. The initiative has analysed the metadata implementation both from thehigh-level point of view (i.e. methodologies, approaches, organisation policies) and from a more technicalone (i.e. recommendation and application of selected metadata standards, data modelling techniques andimplementation of controlled dictionaries).
The RepMet initiative fills a unique and important niche in the broader programmes on data,
information and knowledge management that are conducted nationally and internationally by operators,
regulators and other relevant actors in the radioactive waste management field. This paper provides anoverview of the initiative and the status of the initiative as of the time of writing.
1. RepMet Introduction

in 2014 by the Integration Group for the Safety Case(IGSC) of the Radioactive Waste Management

The Radioactive Waste Repository Metadata
Management (RepMet) initiative was launched1
6th East Asia Forum on Radwaste Management Conference
November 27-29, 2017, Osaka, Japan

Committee (RWMC) at the OECD Nuclear Energy
Agency.

The available data, information and records areaccessed and updated according to management
systems, with the underlying repository allowing
users to locate what they require through searches offull text or the associated metadata.

RepMet analysed and investigated the applicationof metadata, a fundamental tool of the modern dataand information management, within national
programmes for radioactive waste repositories.

Metadata allows context to be stored with dataand provide additional information so that it can belocated, used and reused. It can also be a useful tool
to help waste management organisations todemonstrate that their programmes are appropriatelydriven. Such context-setting information may include
data on quality checking or approval; provenance orownership.

Radioactive Waste Management Organisations(RWMOs) have to manage very large amounts ofdata that they produce and receive to support theiroperational, pre-closure safety cases or otherrequirements. A special characteristic of radioactive
waste repositories is the significant time, typicallymore than one hundred years, between facility
construction and closure. Therefore, data handled by
RWMOs require special treatment to be considered
reliable and consequently usable for such a longperiod.

When considering metadata for a domain (as forRepMet), metadata are typically associated with a setof predefined digital or physical objects, for example
an ID for a waste package or signing date of a quality
log. It is important to remember, however, thatmetadata also cover how these elements are to beconstructed and related to one another (for example
how a waste package relates to a packagingcampaign), the type and range of values they may
take (for example, a package weight must be greaterthan 0 kg), etc.

Within this challenging framework, the main goalof RepMet was to identify sets of metadata whichenable RWMOs to manage their repository data,
information and records in a way that is both suitable
for long-term management and utilisation, andharmonised internationally (e.g. to support the datainteroperability). Furthermore, the initiative workedon the formulation of a consistent set of guiding
principles for capturing and generating metadata, aswell as a shortlist of selected relevant standards and acollection of international good practises.

3. RepMet Scope
The scope of the RepMet initiative includes thefollowing:

Several worldwide RWMOs and researchlaboratories from NEA countries were involved in theRepMet initiative: Andra (France), Enresa (Spain),
JAEA (Japan), Nagra (Switzerland), NDA (UnitedKingdom), NWMO (Canada), ONDRAF/NIRAS(Belgium), Posiva (Finland), PURAM (Hungary),
Sandia National Laboratories (United States), SKB(Sweden) and SÚRAO (Czech Republic). The
RepMet group met twice yearly; working groups,
composed of RepMet members and contractors,
furthered the initiative in the intervening periods.

• Identification of methods and procedures for thegathering and management of data and metadata.

2. Metadata• Identification of methods and principles toguarantee the persistence in time of the above
procedures.

• Justification of the sufficiency of the set of
metadata describing the identified data to support
use and re-use.
• Relationship to safety assessment. The metadata
required for information captured “in the field”
will differ from that required for analysed andderived data that are often used within safetyassessment models. (Safety assessment models
are to be discussed in detail in future work.)

National programmes for radioactive waste
repositories are collecting large amounts of data thatmust be managed throughout the entire period ofinstitutionalised oversight spanning a considerable
amount of time. The data, metadata and related
records also increase in number, type, and quality as
programmes proceed through the successive stages ofrepository development: pre-siting, siting, sitecharacterisation, construction, operations, pre-closureand finally closure. Regulatory and societal approvals
are included in this sequence. Current programmes
are also documenting past repository programmes, sothat current and future generations can understandactions carried out in the past, by retrospectively
adding metadata to help organise and arrange
programme records.

• Guidelines for metadata management.
• Controlled dictionaries and policy as a means ofensuring consistency and reliability of data andcataloguing.
• Use of metadata to support data auditability,verification methods and, if needed, modification.
• Provision of a basis for the exchange and sharingof data between organisations, stakeholders andmember nations, which may be separated acrossgenerations.

2
6th East Asia Forum on Radwaste Management Conference
November 27-29, 2017, Osaka, Japan• Identification of methods and procedures for thedata and metadata gathering and management.

and conditioning processes, are ready for final
disposal at the repository.

RepMet does not intend to promote any
commercial products or services for managing
metadata.

• RepMet/04 – “Repository Library” deals withdata and related metadata which relate to theengineered structures and waste acceptancerequirements of the radioactive waste repositories.

4. RepMet Deliverables

The above Libraries can be used independently ofeach other, however utilising all of the libraries andthe approach outlined in these documents provides
the additional benefit of having a uniform approach todata and metadata management.

Figure 1 illustrates the structure of the RepMet
initiative deliverables that were produced during theinitiative from its launch in 2014 to 2017.

This document includes common techniques andtools that RepMet has adopted for the development ofmultiple libraries and which are deemed useful for
relevant RWMO activities and initiatives:

Figure 1: RepMet Deliverables• RepMet/05 – RepMet Tools & Guidelines
supports the libraries providing several usefultools, methods, guidelines, and approaches thatwere either used in developing the Libraries or areuseful for the RWMO when adopting andimplementing the Libraries.
RepMet will close its activities in 2017. The above
deliverable documents will be made available
publicly in electronic form on the RepMet webpage 1
on the NEA website in the next months.
5. RepMet Approach

Figure 2: RepMet Approach
The first document of the deliverables deals withthe application of metadata in the field of radioactive
waste geological disposal from a general, high-level
point of view:• RepMet/01 – “Metadata in Geological Disposal”
provides an overview and summary of RepMet
goals, deliverables, various aspects of metadata
implementation and issues for consideration.
The following three deliverable documents, theso-called “Libraries”, adopted a more technical pointof view. They discuss the key aspects of data andrelated metadata for selected topics of different
scientific and technical disciplines involved in therealisation of a radioactive waste repository. The
Libraries include conceptual data models (CDMs),
descriptions of data entities, attributes, associatedmetadata and other relevant information:• RepMet/02 – “Site Characterisation Library”
deals with data and related metadata that areconsidered during the selection of thecharacterisation of a site investigated andsurveyed for suitability for radioactive waste
disposal purposes leading up to site selection.

エラー! 参照元が見つかりません。2 shows theprinciples that the RepMet initiative followed for thedevelopment of the libraries and other deliverables.
•• RepMet/03 – “Waste Package Library” deals withdata and related metadata about packaged waste
and spent nuclear fuel that, after proper treatment

High-level approach – RepMet did not consider
the choice of the IT systems for data

1. www.oecd-nea.org/rwm/igsc/repmet.

3
6th East Asia Forum on Radwaste Management Conference
November 27-29, 2017, Osaka, Japanmanagement and the related technology. It lies
outside the initiative scope.
••

analysis for a radioactive waste repository (i.e.
radioactive waste management, engineering andgeoscience) was the core activity of the RepMet
initiative. Table 1 shows the topics that the group
selected for each library from the three disciplines.

Essentiality – The content of the libraries (e.g.
the information about the final waste package forthe safety case) is not exhaustive or universal.
The group defined the minimal and essential
information about the single selected topics.

The structure of the three RepMet libraries isuniform and composed of:• Conceptual data models (CDMs) describing realor abstract objects related to the topic (e.g. the“waste”, the “wasteform”, the “spent nuclear fuel”
or the “disposal module” in the “Waste PackageLibrary”).

General suitability – All the RWMOs,
independently of the RWM programme maturity,
could apply the results of RepMet’s work in amanner considered suitable with their specificcircumstances and needs. In this perspective,
countries currently starting their own RWM
national programmes might look at the current
content as the core information that isrecommended to collect at least in the first stages.
On the other hand, more experienced RWMOs
can extend the information according to theirrequirements and specifications.

•Commonunderstanding–Controlled
dictionaries for library contents such as entities,
data, metadata, properties, etc., are at the root of
the initiative, to promote and facilitate dialogue
among the different organisations.

•Use of international well-consolidated andhigh-quality standards.

• List of properties (alternative called attributes)
describing characteristics of the library objects(e.g. the “mass”, the “content of anions” or the“total alpha activity” of a waste) in the form ofcontrolled dictionaries.
The information related to each property in thelibraries plays a role in the development of a robust
safety case for a radioactive waste repository. The
sources of these pieces of information emanate fromthe same RWMOs involved in the initiative, since theRepMet group conducted analysis and an internalsurvey on data that the same RWMOs are currently
collecting on the library topics. In this sense, RepMet
used CDMs and controlled dictionaries to shape andorganise the safety case information in a way
supporting the common understanding between
different organisations.

The last of the above listed principles of theRepMet approach for the library development
requires additional explanation. As a matter of fact,
the number of international and local standards
relating to metadata management is overwhelming
and as a result does not necessarily help the goal ofstandardisation. Different organisations also favour,or are prescribed to use, different standards.

The safety case information must be maintained
and preserved throughout the repository lifecycle. To
achieve this demanding result, it would not be
sufficient to just maintain the data related to aproperty: e.g. the numeric value (i.e. data) of theactivity of a transuranic radionuclide (i.e. property) ina spent nuclear fuel assembly might be poor inmeaning if the data-user does not know how it wasobtained. It is important to have additional data, alias
metadata according to their classic definition (i.e.
“data about data”), to describe and maintain theinformation associated with the data. RepMet
selected and adopted some metadata standards (i.e.
OGC Observation & Measurement (O&M) metadata
standard – ISO19156, and the Minnesota
Recordkeeping Metadata Standard) to describe theproperties in the RepMet Libraries. These standards
provide some abstract (meta)data models that identify
and arrange metadata to describe the information
about a single property in a way that future users cantrust.

As a principle, RepMet has attempted to selectexisting standards, rather than define its own to avoid
escalating this number further. Selecting the best
standard from the numerous standard candidates that
often overlap or are subsets of each other is acomplex endeavour. Different standards may focus on
different themes.
The principles followed by RepMet when selecting
relevant standards were the following:•The essential minimum is recommended.

•Only standards that would work for all RWMOs
are recommended.

•Less complex standards are given preference ifsuitable.

•Standards proven to work and widely used by theprofession already are favoured.

Table 1: Topics and Disciplines of the RepMet
Libraries

6. RepMet Libraries
The development of the three RepMet Libraries
across the main disciplines involved in the safety case4
6th East Asia Forum on Radwaste Management Conference
November 27-29, 2017, Osaka, Japan

Discipline

Libraries

TopicsRadioactiveWaste
Management

Waste Package

Packaged wasteand spent nuclear
fuel ready forfinal disposal

Engineering

Repository

Geoscience

Site
Characterisation“models” (abstract,deterministic).

Repository
requirements andstructure atclosureGeological andgeophysicalcharacterisationof the repositorysite

7. Closing Remarks
Metadata enables RWMOs to manage their data in awell-organisedmanner,meeting
statutory
requirements and ensuring that data quality is noteroded, confidence in the stored data is kept, and thatthe data remain suitable for support of their future
decisions and operations efforts, and meets therequirements of their designated communities in thepresent and in the future.
RepMet has formulated a consistent set of
guiding principles for metadata management in thecontext of geological repositories. The results of thiswork are useful to operators, regulators and otherrelevant actors. The Libraries and associateddocuments have been prepared with the purpose toprovide generic models, processes and descriptions
that can be tailored to the needs of virtually any
RWMO. These can be regarded as a common basis
for the development of metadata.

stochastic,•

Creation of new RepMet Libraries including
different topics for waste management
pre-closure, e.g. “waste treatment andconditioning”, “plant operations”, “interimstorage of the waste package”.

•

Extension of the current RepMet Libraries (e.g.
maturing, increasing the level of detail).

•

Application of the O&M standard that RepMet
has adopted to support safety assessment process
chains and for the development of the safety case(e.g. new and dedicated RDF/SKOS controlled
dictionaries and models).

•Definition of RDF/SKOS controlled dictionaries
for the IGSC FEP Task Group.

•Definition of conceptual requirements for thecreation of a central metadata database to allow
data from multiple databases (e.g. commercialoff the shelf [COTS] offerings) to be extracted
and combined from a single query. These
requirements should consider the possible
conflicts of interest when handling metadata.

•Formulation of data dictionaries for RWMO
modelling.

8. Disclosure
Sandia National Laboratories is a multi-mission
laboratory managed and operated by National
Technology and Engineering Solutions of Sandia
LLC, a wholly owned subsidiary of Honeywell
International Inc. for the U.S. Department ofEnergy’s National Nuclear Security Administration
under contract DE-NA0003525. This report has
been reviewed and approved for unlimited,unclassified release: SAND2017-11464 C.

RepMet recognises that each RWMO’s activities
are in many respects unique, and that eachradioactive waste site has characteristics that areexclusive to that particular site. However, there arealso many common and general aspects ofradioactive waste management and final disposal.

The opinions expressed and arguments employedherein are those of the author(s) and do notnecessarily reflect the official views of the OECD, theNEA or of the governments of their member
countries.

Each RWMO needs to adapt the provided
models, processes and descriptions in order to meetthe requirements of local regulations, the RWMO’sindividual needs, and the characteristics and theapplied technology of the individual radioactive
waste management operations.

9. References
OGC (Open Geospatial Consortium). Geographic
information
Metadata.
[Online]www.iso.org/obp/ui/#iso:std:iso:19115:ed-1:v1:en.

While RepMet has completed key deliverables inits initial phase, the group recognises the following
outstanding work areas:•geometric,

Minnesota Recordkeeping Metadata Standard, IRM
Standard
20,
Version
1.3[Online]www.mnhs.org/preserve/records/metamrms.php

Development of a complete metadata
structure/database for a safety assessment
tailor-made for the needs of the nuclear waste
industry. Extension of the developed metadata
structure developed by RepMet to encompass
also the data related to the safety case and its

World Wide Web Consortium. SKOS Simple
Knowledge Organization System Primer. [Online]
www.w3.org/TR/skos-primer.

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6th East Asia Forum on Radwaste Management Conference
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