Nuclear Science2019

International Co-operationin Nuclear Data Evaluation
An Extended Summary of the
Collaborative International EvaluatedLibrary Organisation (CIELO) Pilot Project

NEA

Nuclear Science

International Co-operation in Nuclear
Data Evaluation
An Extended Summaryof the Collaborative International
Evaluated Library Organisation (CIELO) Pilot Project© OECD 2019
NEA No. 7498
NUCLEAR ENERGY AGENCY
ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENTORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENTThe OECD is a unique forum where the governments of 36 democracies work together to address the
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expressed and arguments employed herein do not necessarily reflect the official views of theOrganisation or of the governments of its member countries.

NUCLEAR ENERGY AGENCYThe OECD Nuclear Energy Agency (NEA) was established on 1 February 1958. Current NEA membershipconsists of 33 countries: Argentina, Australia, Austria, Belgium, Canada, the Czech Republic, Denmark,Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Luxembourg, Mexico, theNetherlands, Norway, Poland, Portugal, Korea, Romania, Russia, the Slovak Republic, Slovenia, Spain,
Sweden, Switzerland, Turkey, the United Kingdom and the United States. The European Commission
and the International Atomic Energy Agency also take part in the work of the Agency.
The mission of the NEA is:–

to assist its member countries in maintaining and further developing, through international
co-operation, the scientific, technological and legal bases required for a safe, environmentallysound and economical use of nuclear energy for peaceful purposes;–

to provide authoritative assessments and to forge common understandings on key issues as
input to government decisions on nuclear energy policy and to broader OECD analyses in areas
such as energy and the sustainable development of low-carbon economies.

Specific areas of competence of the NEA include the safety and regulation of nuclear activities,
radioactive waste management and decommissioning, radiological protection, nuclear science,
economic and technical analyses of the nuclear fuel cycle, nuclear law and liability, and public
information. The NEA Data Bank provides nuclear data and computer program services forparticipating countries.
This document, as well as any statistical data and map included herein, are without prejudice to the statusof or sovereignty over any territory, to the delimitation of international frontiers and boundaries and to thename of any territory, city or area.
Corrigenda to OECD publications may be found online at: www.oecd.org/about/publishing/corrigenda.htm.
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Cover photos: The Chi-Nu detector array for measuring prompt fission neutron spectra (Los Alamos National Laboratory);
Simulation of the Advanced Test Reactor using new CIELO nuclear data files; U-238 sample and detectors for neutron capture
measurements (Joint Research Centre, Geel).

FOREWORD

Foreword

Complete data representing the relevant nuclear physics are required for thesimulation of nuclear systems. These simulations require many types ofexperimental measurements, theoretical physics, semi-empirical models andsoftware systems, as well as experts to integrate and guide the process. Collectively,
the discipline is known as nuclear data. Separate programmes within various
European countries, as well as in Japan, Russia, the United States and other Nuclear
Energy Agency (NEA) member countries, have been operating such activities formany decades.
The NEA Working Party on International Nuclear Data Evaluation Co-operation(WPEC) was created in 1989, under the aegis of the Nuclear Science Committee (NSC),
to improve the quality and completeness of nuclear data by bringing together
representatives of the major nuclear data evaluation projects of NEA member
countries and of selected invitees. The expert groups and subgroups of the WPEC
typically focus on specific technical topics. The Collaborative International
Evaluated Library Organisation (CIELO) Pilot Project, working under the auspices ofthe WPEC Subgroup 40, was established to generate complete evaluations for aselection of the most important isotopes for parameters in nuclear technologies:
235
U, 238U, 239Pu, 56Fe, 16O and 1H with the aim of improving the accuracy of the data
and resolving previous discrepancies in the overall understanding
The CIELO Pilot Project has been overseeing numerous activities, which recently
resulted in an entire special issue of the Nuclear Data Sheets journal (Issue 148, 2018)
being dedicated to the subject. It has also led to the production of a suite of new
nuclear data evaluations that have been incorporated into major nuclear datalibraries. The outcomes of evaluations include significant harmonisation of
discrepancies between independent programmes, improvements in the performanceof international standard nuclear criticality and neutron transmission benchmarks,
complete uncertainties for nearly all parameters and the use of modern data storage
technologies. Overall, this work has leveraged considerable, parallel andexperimental work in collecting improved experimental measurements to support
nuclear data, while highlighting high-priority areas for further study. A productive
and durable framework for international evaluation was thus established to build
upon lessons learnt. These lessons will continue through new WPEC groups and a
new International Atomic Energy Agency (IAEA) evaluation network, which was
initiated in response to the success of the NEA CIELO Pilot Project.

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TABLE OF CONTENTS

Table of contents

List of abbreviations and acronyms ................................................................................ 7
Motivation for the work ..................................................................................................... 9
New experimental measurements ................................................................................ 11
CIELO evaluated files ........................................................................................................ 13
Fission in 235U and 239Pu ................................................................................................ 13
Capture and scattering in 235,238U and 239Pu ................................................................ 14
Evaluation of 56Fe ........................................................................................................... 14
Evaluation of 16O ............................................................................................................ 15
Final CIELO file versions ............................................................................................... 15
Integral benchmarking .................................................................................................... 17
Results with the Mosteller suite .................................................................................. 18
Results with the van der Marck suite ......................................................................... 20
Uncertainty analyses on criticality benchmarks ...................................................... 21
Discussion and conclusions............................................................................................ 27
References .......................................................................................................................... 31
Appendix A. About this publication .............................................................................. 33

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LIST OF ABBREVIATIONS AND ACRONYMS

List of abbreviations and acronyms

AMS

Accelerator mass spectrometry

ATLF

Above-thermal leakage fraction

BNL

Brookhaven National Laboratory (United States)

BROND

Russian Evaluated Neutron Data Library

CAB

Centro Atómico Bariloche (Argentina)

CEA

Commissariat à l'énergie atomique et aux énergies alternatives(France)

CENDL

China Evaluated Nuclear Data Library

CERN

European Organization for Nuclear Research

CERN n_TOF

Neutron time-of-flight facility at CERN (France)

CIAE

China Institute of Atomic Energy

ENDF

Evaluated Nuclear Data File

CIELO

Collaborative International Evaluated Library Organisation(NEA pilot project)

CIELO-1

Sets of CIELO cross section data adopted by the ENDF
community

CIELO-2

Sets of CIELO cross section data adopted by the JEFF community

DANCE

Detector for Advanced Neutron Capture Experiments

DDCOM

Dispersive coupled-channel optical model

FCA

Fast critical assembly

FWHM

Full width at half maximum

GELINA

Geel Electron LINear Accelerator Facility (Belgium)

HEU

Highly enriched uranium

HMF

Highly enriched uranium metal with fast neutrons

HST

Highly enriched uranium solutions with thermal neutrons

IAEA

International Atomic Energy Agency

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LIST OF ABBREVIATIONS AND ACRONYMICSBEPInternational Criticality Safety Benchmark Evaluation Project
(NEA)

IPPE

Institute of Physics and Power Engineering (Russia)

IRSN

Institut de Radioprotection et de Sûreté Nucléaire (France)

JAEA

Japan Atomic Energy Agency

JEFF

Joint Evaluated Fission and Fusion File (NEA)JENDLJapanese Evaluated Nuclear Data Library

JRC

Joint Research Centre (European Commission)

LANL

Los Alamos National Laboratory (United States)

LCT

Low-enriched uranium compound with thermal neutrons

MCNP

Monte Carlo N-Particle Transport Code

NDaST

Nuclear Data Sensitivity Tool (NEA)

NRG

Nuclear Research and Consultancy Group (Netherlands)

NSC

Nuclear Science Committee (NEA)

Nubar

Average number of neutrons per fission

NUEX

Neutrino excitation of nuclear levels

ORELA

Oak Ridge Electron Linear Accelerator (United States)

ORNL

Oak Ridge National Laboratory (United States)

PFNS

Prompt fission neutron spectra

PMF

Plutonium metal with fast neutrons

PST

Plutonium thermal solutions

ROSFOND

Russian National Library of Neutron Data

RPI

Rensselaer Polytechnic Institute (United States)

TSL

Thermal scattering law

TUNL

Triangle Universities Nuclear Lab (United States)

WPEC

Working Party on International Nuclear Data Evaluation
Co-operation (NEA)

ZPR

Zero Power Reactor

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MOTIVATION FOR THE WORK

Motivation for the work

The physics of nuclear reactions embodies essential information for the design,operation and decommissioning of nuclear systems, with applications spanningenergy, safety, medicine, science, security and a great many other industrial
processes. The types of knowledge required are as diverse as the applications,
including on reaction probabilities (cross-sections) for many different types ofreactions, emitted particle probabilities/energies/angles, probabilities for different
fission fragment formation, and decay processes and their emitted particle data.
Many of these data vary with the incident particle energy, potentially by factors of
one million or more. In addition to the above requirements, it is important to havecorrelated uncertainties for all data in order to quantify and propagate uncertainties
in simulations.
A general-purpose nuclear data library must therefore contain all of thisinformation. It is the role of the nuclear data evaluators to craft databases of
information for all of the elements and isotopes that may be required. Through the
Nuclear Energy Agency (NEA) international EXFOR database, evaluators have accessto a wealth of experimental data to guide this process, but only a small fraction of alibrary can be directly compared with measurements as a result of the extensive
requirements for a general purpose library. Models and computer codes aredeveloped not only to fill these gaps, but to ensure consistency of the data. Becauseof the fundamental challenges presented by the different aspects of relevant nuclear
physics, there is no single model or code that can calculate more than a fraction of
the required data. As a result, many models are in use within every major nuclear
data programme, of which there are several that currently exist around the world.
The integration of these many systems and their respective communities of experts
is the main challenge that nuclear data programme managers face in organising thedelivery of improved nuclear data files.
Each of the major, general purpose nuclear data projects, including ENDF (UnitedStates), JEFF (NEA Data Bank), JENDL (Japan), CENDL (China) and ROSFOND (Russia),
develop and release libraries that include numerous isotopes. An overview of the
progress and history of the libraries released is shown in Figure 1 below.
The libraries draw largely on each other, implicitly recognising the qualities ofthe other projects and their data files. Taking files for five americium isotopes of themost recent JEFF-3.3 as an example; one (241Am) is an evaluation resulting from the
JEFF community, while two (244Am and 244mAm) are taken from the JENDL Actinoid
File 2008 and two (242Am and 242mAm) are from a 1996 Belarusian evaluation (Maslov,
et al. 1997) that was incorporated into the JENDL-3.3 library. A more detailed
inspection of these files reveals that they are also the product of multiple projects.
For example, several of the major curium isotopes, including 242,244,245Cm, include

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MOTIVATION FOR THE WORK

original work from the JEFF community, as well as fission photon multiplicities anddistributions from ENDF/B-VII.1, fission angular distributions for particles from
BROND-2.2, and resonance parameters and fission neutron covariances fromJENDL-4.0. These mélanges do not represent a problem, but rather they demonstrate
the regard that evaluators have for the work of their counterparts around the world.
Figure 1. Overview of the well-known nuclear data libraries and their releases

The routine adoption of data or of complete files between different nuclear data
projects underlines an essential fact: that major nuclear data projects have beencollaborating for several decades. This indirect collaboration has not benefited fromthe co-operation and co-ordination that occurs within each project. The Collaborative
International Evaluated Library Organisation (CIELO) Project was proposed to facilitate
this missing, direct and natural collaboration for a set of high-priority isotopes.

While the objective of the CIELO Project was to discuss, understand anddocument discrepancies, it was not necessarily to resolve all of these discrepancies.
It must be recognised that each evaluation may prioritise different experimental dataor models, target different applications, or elect to use different mechanisms to reacha final file (e.g. use of integral adjustment). Despite official CIELO files being produced
as a result of the subgroup activities (referred to below as the CIELO-1 and CIELO-2
files), not one set was agreed upon by all participants. This result is by itself an
important development. In fact, one important CIELO outcome was an appreciation
for the fact that there must be room for differing ideas in any scientific endeavour.

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NEW EXPERIMENTAL MEASUREMENTS

New experimental measurements

The data within nuclear data libraries cannot be derived from first principles, andexperimental measurements form the basis of all evaluations. These represent
significant costs, in terms of funding, time and the availability of suitably trained(and talented) experimental physicists. Requests for more accurate measurements
require the development of new concepts and equipment, which in turn require
more resources.
Motivated by the new evaluation efforts in the Collaborative International
Evaluated Library Organisation (CIELO) Pilot Project, several new measurement
campaigns were performed in the United States and Europe. Table 1 summarises
the contributions made since 2013, available for use in the production of the CIELO
files, which form the primary deliverable of this subgroup. For more details on theexperiments and their use in the CIELO evaluation process, see the main reference
paper (Chadwick, et al. 2018) and others within that Nuclear Data Sheets 148 special
issue. It should be noted that these do not include the recent measurements thatwere taken into account in the creation of the new International Atomic Energy
Agency (IAEA) standards (Carlson, et al. 2018) and that are documented in this report.
Table 1. Notable experimental contributions during
the course of the CIELO project since 2013
Laboratory
CERN n_TOF
JRC-Geel

LANL

RPI
TUNL

Measured data for CIELO
235,238U ﬁssion cross sections

235,238U neutron capture cross sections
238U neutron capture cross section

Fe inelastic scattering cross section
16O(n, α) cross section
235,238U, 239Pu fission cross sections
235,238U, 239Pu neutron capture cross sections
Prompt fission neutron spectra
Iron inelastic gamma production
235U fission cross section
235U, Fe neutron capture cross sections
238U and Fe semi-diﬀerential scattering
16O total cross section
238U(n,2n) cross sections

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CIELO EVALUATED FILESCIELO evaluated files

The Collaborative International Evaluated Library Organisation (CIELO) Projectfocused on six isotopes, including the “big three” actinides, 235U, 238U and 239Pu, aswell as the primary structural material, 56Fe, and two isotopes that are present innumerous materials, ranging from ceramics and oxides to organic matter and water:1
H and 16O. While these have been the subject of many experiments and nuclear data
evaluations, and are the primary components of systems that have been built with
input depending upon validated nuclear data libraries, differences among data inmajor evaluations are still common and often greater than the evaluateduncertainties. By bringing together experts from multiple evaluation projects, andwith the benefit of the most recent and accurate experimental data, new evaluatedfiles have been created.
In the creation of new evaluations, it is essential to study the full breadth of
relevant physics, including fission, average neutron emission and energy spectra,
scattering, and capture. Only by considering all of these simultaneously, for all
isotopes, has progress been made on building upon the performance of previous
evaluations and improving the performance on targeted benchmarks. The following
sections provide some description of the important findings of this work.

Fission in 235U and 239Pu
Recent IAEA standards (Carlson, et al. 2018) have been issued, which have doubled
the uncertainties on fission cross sections as a result of large (1.2%), systematic
uncertainties that were unrecognised in previous experiments. Efforts were madeto ensure compatibility with both these new standards and the uncertainties in the
CIELO files for 235U and 239Pu. The uncertainties translate directly into increased
uncertainties when calculating quantities such as keff criticality, and they have asignificant impact on many analyses, including statistical comparisons withbenchmarks when nuclear data uncertainties are considered (Capote, et al. 2018).
Although these new fission cross-section uncertainties represent an increase
compared to earlier assessments, the standard subject matter experts view themas more credible. Furthermore, future experimental work might lead to reduced
uncertainties.
The prompt fission neutron spectra (PFNS) provide the source neutron spectra
in a critical fission system, and new experimental evidence has supported a
distribution with a greater lower-energy component, or “softer” spectrum, for both
thermal fission and fission for ~MeV-range incident neutrons on 235U. These findings

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CIELO EVALUATED FILES

have been incorporated into new PFNS evaluations for 235U (Neudecker, et al. 2018).
The experiments for 239Pu are ongoing, and it is expected that future work will beable to revisit the plutonium PFNS.
The average total neutron yield per fission, or nubar, is a highly sensitive
quantity for criticality calculations, and it is routinely adjusted within theexperimental uncertainties by evaluators in order to optimise agreement withintegral experiments. This is unlikely to change in the foreseeable future as thecurrent experimental methods appear to have reached limits that will be difficult toimprove upon.

Capture and scattering in 235,238U and 239Pu
Moving beyond the fission-related quantities in actinides, the ratios with capture
cross sections dictate the fractions of neutrons that undergo fission rather thanbeing absorbed. These have benefited from several capture 238U measurements thathave been used in the IAEA Neutron Standards (2006 and 2017), which have been
integrated within CIELO. Experimental evidence has also motivated the decrease of
the 235U capture cross section from ENDF/B-VII.1 near 1 keV and an increase in the
10 keV region. Future experiments will be useful to corroborate these changed
assessments.
Neutron scattering plays a central role in neutron transport and in reducing
energy and controlling the flight paths of neutrons in a system. New, semidifferential measurements from the Rensselaer Polytechnic Institute and theoreticalmodels have resulted in new 238U inelastic scattering evaluations, and future
measurements are planned for 239Pu. Likewise, uncertainties in the 235U scatteringcross sections in the fast energy range, 100s of keV to MeVs, will require newmeasurements similar to those performed for 238U.
The evaluations in CIELO for these isotopes benefitted greatly or directly adopted
data that was produced in another WPEC activity under Subgroup 34 (NEA, 2014).

Evaluation of 56Fe
The evaluation of iron requires a very detailed representation of the resonating
cross sections up to a relatively high energy in the MeVs. Coupled with therequirement to adequately account for the capture and scattering processes, it
presents a challenge that the available experimental measurements do notadequately constrain. As a result, the space of justifiable evaluations is quite broad,and the evaluator has a great deal of flexibility in selecting the final data. The
consequence of this flexibility is that adjustments to iron are made to optimise
results for integral criticality and transport benchmarks, which must be undertaken
in concert with the other isotopes to which the benchmarks are sensitive. Since
these are, for most benchmarks, the very isotopes considered in the CIELO project,
the performance for the CIELO-1 and CIELO-2 based libraries, ENDF/B-VIII.0 and
JEFF-3.3, are quite good (Herman, et al. 2018). Further experimental data that could

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CIELO EVALUATED FILES

better constrain these evaluation parameters would greatly simplify this process
and assist in harmonising international nuclear data evaluations. It has also been
noted that future work on the elastic and inelastic scatter cross sections, as well as
their angular distributions, is required in order to improve the simulation of neutrontransmission through macroscopic quantities of iron.

Evaluation of 16O
The participants were able to reach a consensus on the values for the low-energy
neutron elastic scattering cross section and the magnitude of the total cross section
up to the fast energy range. The coupling of R-matrix analyses with rigorous studiesof the available experimental data assisted in this, as well as in the evaluation of the(n,α) cross section. Nevertheless, different assessments of the 16O(n,α) cross sections
were made in the CIELO-1 and CIELO-2 libraries – future accurate experiments would
be valuable to resolve these discrepancies. In contrast, the 1H evaluations were
jointly adopted in both CIELO-1 and CIELO-2.

Final CIELO file versions
While harmonisation of evaluations was a stated goal of the CIELO project, theobjective was not to generate one monolithic evaluation.
As the uncertainty data (available in nearly all components of the CIELO files) indicate,
it is not possible to make one authoritative evaluation that reflects the experimental
measurements, let alone nature. It is worth considering that “[the] alternative to
uncertainty is authority, against which science has fought for centuries” (Gleick 1993).

To accommodate the two, self-consistent evaluated file sets that emerged fromthe CIELO activities, two versions were issued. These were labelled CIELO-1 and
CIELO-2 and were later adopted by the ENDF/B-VIII.0 and JEFF-3.3 libraries,
respectively. The contents of these evaluations are numerous but can be generally
broken down into one component for the resonance energy (where cross sections
vary by orders of magnitude) and the fast energy ranges. These are typicallyevaluated separately and integrated to create the final file. Table 2 summarises theleading laboratory or group that evaluated these components for each file in both of
the CIELO versions. It should be noted that these versions do not represent two
evaluations from two segregated communities. Files from the US Oak Ridge and Los
Alamos National Laboratories appear in CIELO-2 and files from the EU Joint ResearchCentre Geel and the French Alternative Energies and Atomic Energy Commission(CEA) appear in CIELO-1. Indeed, some results from participants in the JEFF
community were selected for CIELO-1 and not for CIELO-2.

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CIELO EVALUATED FILES

Table 2. Lead laboratories evaluating CIELO-1 and CIELO-2 databases

16

Isotope

CIELO-1

CIELO-2

1H

LANL/IAEA

LANL/IAEA

16O res.

LANL/JRC-Geel

IRSN/JRC-Geel

16O fast

LANL

LANL

56Fe res.

IAEA/BNLIRSN

56Fe fast

BNL/IAEA/CIAE

JEFF

235U res.

ORNL/IAEA

IRSN/ORNL

235U fast

IAEA+LANL PFNSCEA

238U res.

JRC-Geel

IRSN/CEA

238U fast

IAEA+LANL PFNS

CEA

239Pu res.

ORNL/CEAORNL/CEA

239Pu fast

LANL

CEA

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INTEGRAL BENCHMARKING

Integral benchmarking

Experimental data, such as those provided by the new measurement campaigns
listed in Table 1, are essential for determining the detailed, energy-dependent
values in evaluated files. However, they do not account for information on the
behaviour of full systems of interest to the users of nuclear data. In order to test –and often to improve – the physics in the nuclear data libraries, full simulations ofmacroscopic systems are used. These are referred to as “integral” experiments, since
they effectively integrate the various reaction rates and physics over a range ofenergies. If agreement is found for some integral measurement, it helps validate thedata for the system considered. By validating a suite of nuclear data files for a large
number of independent benchmarks, confidence can be developed in the results ofsimulations for systems that are similar to those within the benchmarking suite.
The standard metric for testing nuclear data libraries is the “reduced” chisquared:
2

1

𝑛𝑛 𝐶𝐶
( 𝑖𝑖�𝐸𝐸 −𝜇𝜇)2

χ = 𝑘𝑘 �𝑖𝑖

𝑖𝑖

𝜎𝜎𝑖𝑖 2,where the calculated and experimental values Ci and Ei are compared with theaveraged value μ, mediated by the uncertainty σi. The degrees of freedom, k, areconsidered in these analyses to be equal to the number of experiments considered
and the experimental uncertainties alone are considered. There are many
complexities raised by the possibilities of considering nuclear data uncertainties andcorrelations between the benchmark measurements, but these are beyond the scopeof the current report.
Reduced chi-squared can be used to test whether the calculated values for a set ofbenchmarks are different from the experimentally measured values in a statisticallysignificant way. No single value is necessarily better or worse than another, but larger values
are generally less likely. It must be stressed that if all the experimental uncertainties
were accurate, and all the calculated values reflected the true physics perfectly, thechi-squared value would not be zero. The expectation value, which many consider atarget value, would be approximately one.

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INTEGRAL BENCHMARKINGThe use of criticality and neutron transmission experiments, available within
NEA benchmark collections, 1 was part of an iterative process in the CIELO work, withfeedback from results and sensitivity analyses providing guidance for evaluators tofocus their efforts. The NEA Nuclear Data Sensitivity Tool (NDaST; Dyrda, et al. 2017)
was used to analyse sensitivity profiles of thousands of benchmarks and pinpoint
specific reactions and energies where updates would improve the evaluated files.
There remains an ongoing concern that the use of integral feedback undermines theexercise of validating nuclear data, as the files could be tailored to simply reproduce
those results. However, to ensure the highest-quality evaluations, experts use allavailable information to model the physics in a way that is faithful to the theory andavailable, differential measurements. The criticism also does not account for thefact that the tailoring, or “tuning” of a data file, is typically done to match a small
fraction of the available integral data, and the improved databases are thencompared against very large compilations of other integral data.
Results presented here were obtained by processing the evaluated nuclear data
files with the NJOY code (MacFarlane, et al. 2018) and then simulating a set ofbenchmark scenarios using the MCNP® version 6 Monte Carlo transport code
(Goorley, et al. 2012).

Results with the Mosteller suite
Although there are thousands of benchmarks that were considered in the
Collaborative International Evaluated Library Organisation (CIELO) Pilot Project, a
subset of 119, known as the “Mosteller suite” have been systematically modelled in
MCNP® by the Los Alamos National Laboratory, which is responsible for the code
itself. Final results for the CIELO-1 and CIELO-2 evaluations, as well as the
ENDF/B-VII.1 results, for reference, are shown in Figure 1 alongside the values for
CIELO-1 (as adopted in ENDF/B-VIII.0) and CIELO-2 (as adopted in JEFF-3.3). The
improvement seen for ENDF is similar for the JEFF library with the new version.
A small subset of these benchmarks is responsible for the majority of the total
chi-squared value. Most notably, those of the Jemimas (fast spectrum, metal withintermediate-enriched uranium) and ZEUS (intermediate spectrum, metal withhighly enriched uranium) benchmarks provide nearly half of the chi-squared for
ENDF/B-VII.1. This represents cases with differences between the calculated andexperimental criticality values that are many multiples of the experimental
uncertainty. The new CIELO evaluations reduce these by better than half,
dominating the improvement in performance as represented by a decrease in the
total chi-squared.
While the CIELO-1 chi-squared value is slightly lower than that for CIELO-2, itshould be noted that these are still largely a result of a small subset of benchmarks.
For example, the difference between CIELO-1 and CIELO-2 for Jemima-4, Thor andtwo of the ZEUS benchmarks are each, individually, greater than the difference in the

118

The NEA benchmark collections include neutronic parameters other than criticality(e.g. flux distributions, spectral indices, reactivity data, βeff and others).

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INTEGRAL BENCHMARKING

total chi-squared between these two evaluations. If the performance on just one ofthese was reversed, the apparent superiority between these two would be reversed.
This underlines the sensitivity of this statistic on individual cases, as well as the fickle
nature of chi-squared comparisons and the selection of benchmark cases. However,the better agreement found for all these challenging benchmarks, while retaining
excellent performance in all other cases, is a significant accomplishment.
Breaking down the results by benchmark materials, as seen in Figure 2, offers aperspective on the systems that have been affected by the new data files. These areclassified as systems made of:•

PU for plutonium;•

HEU for highly enriched uranium;•

IEU for intermediate-enriched uranium;•

LEU for low-enriched uranium;

•

233

•

MIX for plutonium-uranium mixtures.

U for systems with the 233U isotope (rather than 235,238U);

It should be noted that these include cases ranging from bare metal sphere to
solutions, with a range of geometries and average neutron spectra, as well as
experiments from several NEA member countries.
Figure 1. Cumulative, reduced chi-squared values for
the Mosteller suite of criticality benchmarks

Note: CIELO-1 (as ENDF/B-VIII.0) and CIELO-2 (as JEFF-3.3) results arecompared with those of ENDF/B-VII.1. A selection of benchmarks with
noteworthy results is highlighted.
Source: Adapted from Nuclear Data Sheets 148, February 2018: 189-213.

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INTEGRAL BENCHMARKINGThe general result for both ENDF and JEFF is a decrease in the total chi-squared
values for several systems that have large values with previous releases. CIELO-1 is
responsible for improving the ENDF/B-VIII.0 plutonium, highly- and intermediateenriched 235U uranium benchmarks. The CIELO-2 impact on the JEFF files is similarly
impressive, with considerable improvement for the highly- and intermediateenriched uranium. The low-enriched subset is more difficult to reconcile and may
require further study for CIELO-2.
The fluctuations between the different JEFF releases in the highly enrichedbenchmarks highlight a very important feature that may be forgotten by readers
who are accustomed to seeing figures of universal improvement: it is very
challenging to produce nuclear data evaluations that correct some discrepancy withexperiment, while maintaining the same performance in all other benchmarks.
Figure 2. Breakdown of the 119 “Mosteller suite” reduced chi-squared results bymaterial, considering previous and current releases of the ENDF and JEFF
libraries, which now contain the CIELO-1 and CIELO-2 evaluated files

Source: Adapted from Nuclear Data Sheets 148, February 2018: 189-213.

Results with the van der Marck suite
While the Mosteller suite of 119 benchmarks is highly regarded for the purpose of
integral testing, there are thousands of integral measurements within theInternational Criticality Safety Benchmark Evaluation Project (ICSBEP). The ICSBEP
is not specifically tasked with the production of input files for simulation codes, andsuch suites of files require significant efforts to produce. The set of MCNP® inputs

20

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INTEGRAL BENCHMARKING

created by S. van der Marck, of the Dutch Nuclear Research and Consultancy Group,
includes 1766 cases. Reduced chi-squared results for the breakdown of benchmarksby material are shown in Figure 3.
Over this large set of benchmarks, the trends are more difficult to interpret. The
U evaluation in ENDF/B-VIII.0 is a new file, based on JENDL-4.0 with updates to the2006 IAEA Standard and with an increase to the average neutron release in theepithermal energy range. These substantially decreased the chi-squared values inseveral benchmarks. The JEFF-3.3 233U file is taken from ENDF/B-VII.1 and is
responsible for the increase in chi-squared. It must be stressed that these values are
dominated, as in the Mosteller suite shown in Figure 1, by a subset of benchmarks
with discrepant results. Clearly, not all of these were targeted in the CIELO project
and the significant improvement in the Mosteller suite does not translate directly to
a comparable improvement in some other sets of benchmarks.
233

Figure 3. Breakdown of the 1766 “van der Marck suite” reduced chi-squared
results by material, considering previous and current releases of the ENDF and
JEFF libraries, which now contain the CIELO-1 and CIELO-2 evaluated files, aswell as the JENDL-4.0u library

Source: Adapted from Nuclear Data Sheets 148, February 2018: 189-213.

Uncertainty analyses on criticality benchmarks
Uncertainty calculations have been performed using the NEA NDaST tool, which
couples benchmark sensitivity matrices with input nuclear data covariances.
Examples of the uncertainties in the nuclear data at 1 MeV were shown in Tables 6
and 7 in the Nuclear Data Sheets paper by Chadwick (2018). The results for the Jezebel

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INTEGRAL BENCHMARKING

fast plutonium sphere assembly are shown in Tables 3 and 4, and results for the fast
Godiva highly enriched uranium sphere assembly are shown in Table 6. The values
shown in this table illustrate some of the points emphasised earlier in this report on
covariances, namely:•

the keff uncertainties calculated from the covariances largely exceed themeasured uncertainty (second row from bottom), yet the mean values agree
very well (bottom row), reflecting the calibration process that was employed;•

there are significant differences sometimes in uncertainties from individual
reaction channels that our subject matter experts assess;•uncertainties do not always diminish with time; sometimes the new
evaluations embody larger uncertainty assessments, reflecting a view thatthe previous assessments were unrealistically small, and that previously-unappreciated systematic errors have been identified.

The Jezebel plutonium benchmark demonstrates the effects of the new fission
cross section uncertainties introduced via the IAEA Neutron Standards, as well as anincrease in the PFNS uncertainties. It must be noted that anti-correlations between
reaction channels decreases the summed uncertainty below what would be
expected from a fully uncorrelated case. The Godiva benchmark shows a more
complex picture for the change between ENDF/B-VII.1 and the CIELO-1 based
ENDF/B-VIII.0, where fission and capture channels have substantially changed theircovariances, resulting in, respectively, increases and decreases that are nearly
equivalent. The decrease in the PFNS uncertainty because of the new evaluation andnew inelastic covariance data results ultimately in a lower uncertainty. For the
Godiva benchmark, this uncertainty (1 036 pcm) is, as expected, well above theexperimental value of 100 pcm. This reflects a well-known fact that some integral
experiments are more precisely measured than individual, fundamental quantities(e.g. a specific cross section or emitted energy spectrum) to which the integral values
are sensitive.
The large spread in values between uncertainties in the major nuclear data libraries
highlights the fact that this is an active area of research with significant, ongoing
revision much greater than the evaluation of the nominal data. Understanding themethodologies behind these evaluations will be a major focus for upcoming activities.

The values quoted in Tables 3 and 4 are not in entire agreement with those of
the CIELO Nuclear Data Sheets publication, as a result of the adjustment of covariancematrices that occurred between the fifth and sixth release candidates of CIELO-1.
Between these two versions, inelastic scattering cross section and nubar covarianceswere re-evaluated, ultimately reducing keff criticality uncertainties, in the case of theGodiva benchmark, by over 400 and 100 pcm, respectively. The values in this reportreflect the final ENDF/B-VIII.0 and CIELO-1 evaluations.

22

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INTEGRAL BENCHMARKING

Table 3. Uncertainties for the Jezebel (PMF1) benchmark criticality (keff), based on
NDaST and MCNP simulations that use the 239Pu covariance uncertainty data as
calculated

ENDF/B-VIII.0
Jezebelkeff Unc.
(pcm)

ENDF/B-VII.1
Jezebelkeff Unc.
(pcm)

JEFF-3.3
Jezebelkeff Unc.
(pcm)

JENDL-4.0u1
Jezebelkeff Unc.
(pcm)

Fission

903

331

305

434

ν (nubar)

316

81

413

209

PFNS

188

186

443

286

Elastic

462

438

90

198

Inelastic

785

797

150

250

Capture

66

74

30

59

CorrelatedSum±1 041

±562

±645

±648

Exp. Uncert.

±110

Notes: Units are in pcm, which is 1 in 100 000 of keff. The summed value is less than the summed individual
values in quadrature owing to correlations between the various channels. The experimental uncertainty on
keff is shown for comparison, where here we show the most recent PMF1rev4 assessment as opposed to theolder uncertainty value of 200 pcm. All uncertainties are quoted at the 1-sigma confidence level.

Table 4. Uncertainties for the Godiva (HMF1-1) benchmark criticality (keff), basedon NDaST and MCNP simulations that use the 235U covariance uncertainty data
ENDF/B-VIII.0
Godiva (HMF1-1)
keff Unc.
(pcm)

ENDF/B-VII.1
Godiva (HMF1-1)
keff Unc.
(pcm)

JEFF-3.3
Godiva (HMF1-1)
keff Unc.
(pcm)

JENDL-4.0u1
Godiva (HMF1-1)
keff Unc.
(pcm)

Fission

788

269

648

320

ν (nubar)

400

545

510

274

PFNS

124

276

364

176

Elastic

276

294

109

426

Inelastic

244

616

698

681

Capture

281

873

375

269

±1 036±1 220±1 342±962

Correlated Sum
Exp. Uncert.

±100

Notes: Units are in pcm, which is 1 in 100 000 of keff. The summed value is less than the summed
individual values in quadrature owing to correlations between the various channels. The experimental
uncertainty on keff is shown for comparison. All uncertainties are quoted at the 1-sigma confidence level.

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INTEGRAL BENCHMARKINGThe global picture of uncertainties may be probed using the NEA NDaST tool, as
shown in Figure 4. Both the CIELO-1 and CIELO-2 evaluated covariances have been
analysed, with uncertainties broken down into:•[σ] the correlated contributions from all cross-section uncertainties, including
both energy-dependent correlations for each reaction channel and correlations
between different reaction channels, as one cross section uncertainty;•[ν] the uncertainties from the neutron yield per fission, or “nubar”;•[χ] the uncertainties in the prompt fission neutron spectra.
Figure 4. Aggregate uncertainties for 4519 benchmarks calculatedwith NDaST for CIELO-1 and CIELO-2 actinide evaluations

Uncertainties are broken down into cross sections (σ), fission neutron yield(ν) and prompt fission neutron spectra (χ). The benchmarks are broken
down by material and spectrum, with either a high-energy (FAST) spectrum
or highly thermalised, lower-energy (THERM) spectrum. Averageexperimental uncertainties are shown in the background.

This meta-analysis, with each bar summarising averages over hundreds ofsimulations, shows that the application of the nuclear data covariances to any of alarge number of different systems results in uncertainties with non-negligible
differences. Several key differences between the aggregate CIELO-1 and CIELO-2
uncertainties were found in the calculation of uncertainties in integral keff criticality.
These include:•24

the use of IAEA standards for plutonium cross section uncertainties in
CIELO-1 results in considerably larger uncertainties in plutonium keff thanfound with CIELO-2;

RESULTS OF THE COLLABORATIVE INTERNATIONAL EVALUATED LIBRARY ORGANISATION (CIELO) PROJECT, NEA No.7498 © OECD 2019

INTEGRAL BENCHMARKING•

the CIELO-2 HEU cross section uncertainties for fast systems are much larger
than the IAEA standards used in CIELO-1;•

the PFNS uncertainties in highly enriched uranium (HEU) and plutonium
systems for CIELO-2 are approximately twice those for the new CIELO-1
evaluations;•nubar multiplicity (yield) uncertainties in CIELO-2 result in approximately
100 pcm higher uncertainties than with CIELO-1, for all systems except 233U.

There are thus different subject matter experts making different (in some cases,very different) uncertainty assessments regarding knowledge of the fundamental
data. A goal for future collaborative work is to understand, and possibly remove,these discrepancies.

RESULTS OF THE COLLABORATIVE INTERNATIONAL EVALUATED LIBRARY ORGANISATION (CIELO) PROJECT, NEA No.7498 © OECD 201925

DISCUSSION AND CONCLUSIONS

Discussion and conclusions

The Nuclear Energy Agency (NEA) Collaborative International Evaluated Library
Organisation (CIELO) Pilot Project has been highly successful in bringing together
experts from across multiple evaluation projects to collaborate in the production of
new evaluated nuclear data files for several of the most influential isotopes. The
new files that have been adopted by the ENDF/B-VIII.0 and JEFF-3.3 libraries improve
performance in carefully selected criticality benchmarks, as well as in global testing.
While considerable efforts were made to adopt evaluations with the standards ofthe International Atomic Energy Agency (IAEA), as well as harmonised with otherdata, it was recognised that independent evaluations from participating evaluation
projects must be supported so as to allow choices to be made within the constraints
established by experimental uncertainties.
While the evaluations are not identical, the results from the calculation of
integral benchmarks show remarkable agreement between the results from both
CIELO-1 and CIELO-2 evaluations. Figure 5 below shows the breakdown of thedifferences between the CIELO-1 and CIELO-2 evaluations for bare metal spherebenchmarks of 239Pu (Jezebel) and 235U (Godiva), respectively. In each case, switching
one cross section between the two files has an effect that may be more than double
the experimental uncertainty, yet the sum of all these is very close to zero. This trend
is also highlighted in the uncertainty analyses shown in Tables 3 and 4 of this report.
The combination of relatively large uncertainties and the need to find agreement on
well-known benchmark simulations results in evaluations with differences that tend
to compensate for each other. In the case of elastic and inelastic scattering, physicalanti-correlations are the direct equivalent, and the apparent compensation in Figure 5
is simply a reflection of this well-motivated correlation. Some differences between
evaluations may therefore only reflect selections within a distribution of equallyjustifiable evaluations, as constrained by experiment.
Uncertainties remain an area where harmonisation has not been as successful.
It must be underlined that the evaluation of correlated uncertainties is a much more
recent, and in many ways complex, addition to nuclear data files. Many parts ofevaluated nuclear data files still do not possess any uncertainties, let alone fullcovariance matrices. The ongoing work within the NEA WPEC Subgroup 44 should
contribute to progress on this topic, as well as other activities within the nuclear
data evaluation projects.

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DISCUSSION AND CONCLUSIONS

Figure 5. Waterfall of the differences between the CIELO-2 (left) and CIELO-1(right) evaluations in the simulation of the Jezebel bare plutonium spherebenchmark (PMF1)

Contributions are broken down by components of the nuclear data file,including fission neutron yield (ν), prompt fission neutron spectra (PFNS)
and various reaction cross sections. The experimental uncertainty is shown
as a grey band. Each coloured band indicates the effect of substituting thatcomponent from the other evaluation.
Source: Adapted from Nuclear Data Sheets 148, February 2018: 189-213.

Several areas have been highlighted for further experimental data, including thecontinuation of some experimental campaigns carried out during the CIELO project,but on other high-priority isotopes. Notably, this includes the plutonium isotopes,
including more work on 239Pu, but while considering the other isotopes in parallel.
Several other experiments are anticipated in the coming years and these would bewell-paired with collaborative evaluation projects that will follow the success of the
CIELO pilot.
Rapid processing and benchmarking were identified in this work as
indispensable feedback. The availability of modern techniques and readily available
computing power allows us to automate half of the evaluation-validation cycle. Thiswas demonstrated with the NEA NDaST system, which automatically analysed
thousands of datasets to provide prompt information to evaluators that historicallytook months to assemble. The expansion of its capabilities to include otherneutronic parameters and sensitivities for even more systems will be essential for
subsequent activities. The next phase of work will require us to take full advantageof this opportunity to integrate a processing and benchmarking framework forevaluators to receive immediate information on nuclear data files. The
transformation of the file evaluation process (including all model codes, inputs andother expert guidance) into an automatable system remains the last challenge

28

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DISCUSSION AND CONCLUSIONS

before we may fully close the evaluation-validation loop. With the rapid
advancement of Big Data and Machine Learning techniques, the opportunity toapply them to a fully encapsulated nuclear data system would be one of the mostnatural directions to pursue.
Figure 6. Waterfall of the differences between the CIELO-2 (left)
and CIELO-1 (right) evaluations in the simulation of the Godiva bare235
U sphere benchmark (HMF1)

Contributions are broken down by components of the nuclear data file,including fission neutron yield (ν), prompt fission neutron spectra (PFNS),and various reaction cross sections. The experimental uncertainty is shown
as a grey band. Each coloured band indicates the effect of substituting thatcomponent from the other evaluation.
Source: Adapted from Nuclear Data Sheets 148, February 2018: 189-213.

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REFERENCES

References

Capote, R. et al. (2018), “IAEA CIELO evaluation of neutron-induced reactions on 235U
and 238U targets”, Nuclear Data Sheets, Vol. 148, pp. 254-292, Academic Press,
Cambridge, MA.
Carlson, A.D. et al. (2018), “Evaluation of the neutron data standards”, Nuclear Data
Sheets, Vol. 148, pp. 143-188, Academic Press, Cambridge, MA.
Chadwick, M.B. et al. (2018), “CIELO collaboration summary results: International
evaluations of neutron reactions on uranium, plutonium, iron, oxygen andhydrogen”, Nuclear Data Sheets, Vol. 148, pp. 189-213, Academic Press, Cambridge,MA.
Devlin, M. et al. (2018), “The prompt fission neutron spectrum of 235U(n,f) below 2.5
MeV for incident neutrons from 0.7 to 20 MeV”, Nuclear Data Sheets, Vol. 148,
pp. 322-337, Academic Press, Cambridge, MA.
Dyrda, J. et al. (2017), “New features and improved uncertainty analysis in the NEA
nuclear data sensitivity tool (NDaST)”, edited by A. Plompen et al., EPJ Web ofConferences (EDP Sciences), Vol. 146 (9 2017), No. 06026.
Gleick, J. (1993), Genius: The Life and Science of Richard Feynman, Vintage Books, New York.
Goorley, T. et al. (2012), “Initial MCNP6 Release Overview”, Nuclear Technology,
Vol. 180, No. 3, pp. 298-315, Taylor & Francis, Abingdon.
Herman, M. et al. (2018), “Evaluation of Neutron Reactions on Iron Isotopes for CIELO
and ENDF/B-VIII.0”, Nuclear Data Sheets; Vol. 148, pp. 214-253, Academic Press,
Cambridge, MA.
MacFarlane, R.E. et al. (2018), “The NJOY Nuclear Data Processing System, Version
2016”, Los Alamos National Laboratory, Los Alamos, New Mexico.
Maslov, V.M. et al. (1997), Evaluation of Neutron Data for Americium-242m, INDC(BLR)007, IAEA, Vienna, Austria.
Mosby, S. et al. (2018), “239Pu(n,γ) from 10 eV to 1.3 MeV”, Nuclear Data Sheets, Vol. 148,
pp. 312-321, Academic Press, Cambridge, MA.
Neudecker, D. et al. (2018), “Evaluations of Energy Spectra of Neutrons Emitted
Promptly in Neutron-induced Fission of 235U and 239Pu”, Nuclear Data Sheets, Vol.
148, pp. 293-311, Academic Press, Cambridge, MA.
NEA (2018), International Handbook of Evaluated Criticality Safety Benchmark Experiments,
NEA No. 7360, OECD, Paris.
NEA (2014), “Co-ordinated Evaluation of Plutonium-239 in the Resonance Region”,
NEA/NSC/WPEC/DOC(2014)447.

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APPENDIX A. ABOUT THIS PUBLICATION

Appendix A. About this publication

The Nuclear Energy Agency (NEA) would like to acknowledge the contribution of allof the scientists involved in the NEA Working Party on International Nuclear Data
Evaluation Co-operation (WPEC) Subgroup 40 (SG40). In particular, the NEA wishes
to express its gratitude to researchers and experts across different institutions who
participated in WPEC SG40 meetings. The list of contributors can be found below.
Oscar Cabellos and Michael Fleming provided valuable support in drafting andco-ordinating this report.

A CIELO collaboration team photo, from the kick-off meeting on 5-8 November 2013 in Geel, Belgium.

Contributors
M.B. Chadwick

Los Alamos National Laboratory, Los Alamos, NM 87545,
United States

R. Capote
A. Trkov

NAPC–Nuclear Data Section, International Atomic Energy
Agency, Vienna, Austria

M.W. Herman
D.A. Brown

National Nuclear Data Center, Brookhaven National
Laboratory, Upton, NY 11973-5000, United States

G.M. Hale
A.C. Kahler
P. Talou

Los Alamos National Laboratory, Los Alamos, NM 87545,
United States

A.J. Plompen
P. Schillebeeckx

European Commission, Joint Research Center, Retieseweg
111, B-2440, Geel, Belgium

M.T. Pigni

Oak Ridge National Laboratory, Oak Ridge, TN 37831-6171,
United States

RESULTS OF THE COLLABORATIVE INTERNATIONAL EVALUATED LIBRARY ORGANISATION (CIELO) PROJECT, NEA No.7498 © OECD 201933

APPENDIX A. ABOUT THIS PUBLICATION

L. LealInstitut de Radioprotection et de Sûreté Nucléaire, Paris,
FranceY. DanonRensselaer Polytechnic Institute, Troy, NY 12180, UnitedStatesA.D. Carlson

National Institute of Standards and Technology,
Gaithersburg, MD, United States

P. Romain
B. Morillon
E. Bauge

Commissariat à l’énergie atomique et aux énergies
alternatives, DAM Ile de France, F-91297 Arpajon, France

F.-J. Hambsch
S. Kopecky
G. Giorginis

European Commission, Joint Research Center, Retieseweg
111, B-2440, Geel, Belgium

T. Kawano
J. Lestone
D. Neudecker
M. Rising
M. Paris

Los Alamos National Laboratory, Los Alamos, NM 87545,
United States

G.P.A. Nobre
R. ArcillaNational Nuclear Data Center, Brookhaven National
Laboratory, Upton, NY 11973-5000, United States

O. Cabellos
I. HillE. Dupont

Nuclear Energy Agency, OECD, Paris, France

A.J. Koning

NAPC–Nuclear Data Section, International Atomic Energy
Agency, Vienna, Austria

D. Cano-Ott
E. Mendoza
J. Balibrea

Centro de Investigaciones Energéticas Medioambientales yTecnólogicas, Madrid, Spain

C. Paradela

European Commission, Joint Research Center, Retieseweg
111, B-2440, Geel, Belgium

I. Durán

Universidade de Santiago de Compostela, Santiago deCompostela, Spain

J. Qian
Z. Ge
T. LiuChina Nuclear Data Center, P.O. Box 275-41, Beijing 102413,
China

L. Hanlin
X. RuanW. Haicheng

China Institute of Atomic Energy, P.O. Box 275-41, Beijing
102413, China

M. SinNuclear Physics Department, Bucharest University,
Bucharest-Magurele, Romania

34

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APPENDIX A

G. Noguere
D. Bernard
R. Jacqmin
O. Bouland
C. De Saint Jean

Commissariat à l’énergie atomique et aux énergies
alternatives, Nuclear Energy Division, Cadarache, Saint-Paullez-Durance, France

V.G. Pronyaev

PI Atomstandart at SC Rosatom, Moscow, Russia

A.V. Ignatyuk

Institute of Physics and Power Engineering, Obninsk, Russia

K. Yokoyama
M. Ishikawa
T. Fukahori
N. Iwamoto
O. Iwamoto
S. Kunieda

Japan Atomic Energy Agency, Tokai-mura, 319-1195 Japan

C.R. Lubitz

Knolls Atomic Power Laboratory, Schenectady, NY, UnitedStatesM. Salvatores
G. Palmiotti

Idaho National Laboratory, Idaho Falls, ID, United States

I. Kodeli

Jozef Stefan Institute, Ljubljana, Slovenia

B. Kiedrowski

Department of Nuclear Engineering, Michigan University,
Michigan, United States

D. Roubtsov

Canadian Nuclear Laboratories (CNL), Chalk River, Ontario,
CanadaI. Thompson
S. Quaglioni

Lawrence Livermore National Laboratory, Livermore, CA,
United States

H.I. Kim
Y.O. Lee

Korean Atomic Energy Research Institute, Daejeon, Korea

U. Fischer
S. Simakov

Karlsruhe Institute of Technology, Karlsruhe, Germany

M. Dunn
K. Guber

Oak Ridge National Laboratory, Oak Ridge, TN 37831-6171,
United States

J.I. Márquez Damián
F. Cantargi

Centro Atómico Bariloche, Argentina

I. Sirakov

Institute for Nuclear Research and Nuclear Energy, BAS, BG1784 Sofia, Bulgaria

N. Otuka

NAPC–Nuclear Data Section, International Atomic Energy
Agency, Vienna, Austria

A. Daskalakis
B.J. McDermott

Naval Nuclear Laboratory, P.O. Box 1072, Schenectady, NY
12301-1072

S.C. van der Marck

Nuclear Research and Consultancy Group, P.O. Box 25, NL1755, ZG Petten, The Netherlands

RESULTS OF THE COLLABORATIVE INTERNATIONAL EVALUATED LIBRARY ORGANISATION (CIELO) PROJECT, NEA No.7498 © OECD 201935

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International Co-operationin Nuclear Data Evaluation

Current knowledge of the nuclear physics of fuels and materials provides anunderstanding and simulation of the operations of nuclear reactors and other systems,
both under ordinary and exceptional circumstances. As part of a broad spectrumof collaborative activities underpinning research in basic nuclear sciences, theNuclear Energy Agency (NEA) is supporting collaboration between experimentalists,
theoreticians and modelling experts to advance the state of the art in nuclear data.
This report offers an overview of collective results from 31 institutions in 15 NEA
member countries, along with results from technical experts in the People’s Republicof China, in the context of the NEA Collaborative International Evaluated Library
Organisation (CIELO) Pilot Project. It reviews recent developments resulting fromnew measurements and semi-empirical models, as well as the validation of the CIELO
nuclear data evaluations against suites of systems representing a wide range of current
and future nuclear facilities. The CIELO project has delivered new, evaluated data for
the isotopes of uranium, plutonium, iron, oxygen and hydrogen, which have been
adopted in all nuclear data libraries released since the CIELO project was completed.

Nuclear Energy Agency (NEA)
46, quai Alphonse Le Gallo
92100 Boulogne-Billancourt, France+33 (0)1 73 21 28 19
nea@oecd-nea.org www.oecd-nea.org

NEA No. 7498