atw 2018-1

atw Vol. 63 (2018) | Issue 1 ı January
ETSON Strategic Orientations on Research
Activities. ETSON Research Group Activity
J.P. Van Dorsselaere, M. Barrachin, D. Millington, M. Adorni, M. Hrehor, F. Mascari, A. Schaffrath, I.
Tiselj, E. Uspuras, Y. Yamamoto, D. Gumenyuk, N. Fedotova, O. Cronvall and P. Liska
1 Introduction In October 2011, ETSON published the “Position Paper of the Technical Safety Organizations:
Research Needs in Nuclear Safety for Gen 2 and Gen 3 NPPs” [1]. This paper, published only a few months after the
Fukushima-Daiichi severe accidents in Japan, presented the R&D priorities on the main pending safety issues. It was
produced by the ETSON Research Group (ERG) that has the mandate of identifying and prioritizing safety research
needs, sharing information on research projects in which ETSON members are involved, defining and launching new
research projects and disseminating knowledge among ETSON members.
Six years after the above publication, many R&D international
projects in frames such as OECD/NEA/CSNI and
Euratom have finished and others have started. In
particular a lot of work was done (and is going on…) on
the analysis of the Fukushima-Daiichi severe accidents.
Meanwhile a roadmap on research on Gen.II and III
­nuclear power plants (NPP), including safety aspects,
was elaborated by the NUGENIA association and published
in 2013 [2], followed in April 2015 by a more detailed
­document as “NUGENIA global vision” [3].
Thus in 2016-2017, the ERG judged it necessary to
perform an update of the ETSON ranking of R&D priorities,
accounting for recent outcomes of research projects (and,
for severe accidents, knowledge gained on the Fukushima-
Daiichi accidents) and for the NUGENIA R&D roadmaps.
The main objective was to underline a possible convergence
of topics for further R&D, but accounting for current
international R&D projects to avoid duplication of efforts.
2 Process of ranking of priorities
Thirteen ETSON members participated to the exercise
focusing on the safety aspects with the challenge to agree
on a short list of high priority topics and avoid the topics
where significant R&D is ongoing. A good example of
the latter case is In-Vessel-Melt-Retention during a severe
accident where many organizations from Europe (and
beyond) participate in the IVMR H2020 project [4]. For
the sake of simplification, the process was based on the
list of R&D challenges and issues from the NUGENIA
roadmap (each challenge includes several specific issues).
The partners were asked to:
• Select up to 10 highest-priority challenges: give
the mark 1 for the most important,…, 10 for the less
important,
• Then, for each of them, select up to 3 issues: give
the mark 1 for the most important..., 3 for the less
important.
The ranking process was based on the list of R&D highpriority
issues (around 150) from the latest NUGENIA
R&D roadmap. This list covers the 6 following topical
areas: plant safety and risk assessment, severe accidents,
improved reactor operation, integrity assessment of
systems, structures and components, fuel development,
waste and spent fuel management and decommissioning,
innovative LWR design and technology.
The results indicated a rather large scattering of votes
on issues but also the possibility of identifying issues with
a majority of votes. The average ranking was the sum of
marks divided by number of votes. The combined ranking
of challenges and issues was then obtained as “challenge
average ranking” multiplied by the “issue average ranking”.
The smallest figures have the highest priority.
Eight issues, described in the Section 3, were selected
as the highest priority (the order of presentation does not
represent a decreasing order of priority, the issues are in
the order of the NUGENIA roadmap). This Section
summarizes the importance of the issue for safety, the
state of knowledge and the remaining gaps, and the international
context such as ongoing or starting R&D projects.
3 High priority issues
3.1 Improved thermal-hydraulics evaluation
for the existing plants
Most of the thermal-hydraulic phenomena during
­accidents in NPPs occur at the scale of NPP cooling
systems (thermal-hydraulics in Spent Fuel Pools or SFP is
­addressed in § 3.5). The NPP response often represents a
complex interplay of the processes and phenomena in the
subsystems, which can be reproduced or analyzed only
with an experimental facility with a similar complexity or
with a simulation system code that contains models of all
relevant subsystems. Large integral facilities and system
codes thus represent a basis for NPP safety analyses. More
or less an integral facility was built in the past (or is being
built) to correspond to every major NPP type, and thus was
(or is) used to examine the plant performance during
safety relevant scenarios. Such review of integral facilities
and experiments was prepared by OECD/NEA/CSNI [5].
Some of these facilities have already been dismantled,
some of them are maintained (PKL in Germany, as well as
INKA for Gen.3+ BWR safety systems, and LSTF in Japan),
while the countries with long term nuclear goals upgrade
(MOTEL in Finland) or build entirely new (ACME in China)
facilities. These experiments were and are still used for
­validation and verification of system codes (CATHARE,
ATHLET, TRACE, RELAP ...) that represent indispensable
tools for safety analyses.
A complementary approach to the integral thermalhydraulics
testing is the “bottom-up” approach, which
actually means experimental and numerical studies of
­separate effects at larger scales under well-defined initial
and boundary conditions. These test facilities are more
accessible for academic institutions and can be roughly
divided into problems of single-phase and two(multi)-
phase flow phenomena. Single-phase experiments and
computational fluid dynamics (CFD) can be considered a
mature research field, where even blind predictions of
rather complex flows with heat transfer (pressurized
thermal shock, natural convection) and mixing of species
atw-Special „Eurosafe
2017“. In cooperation
with the EUROSAFE
2017 partners,
Bel V (Belgium),
CSN (Spain), CV REZ
(Czech Republic),
MTA EK (Hungary),
GRS ( Germany), ANVS
(The Netherlands),
INRNE BAS (Bulgaria),
IRSN (France), NRA
(Japan), JSI (Slovenia),
LEI (Lithuania),
PSI (Switzerland),
SSM (Sweden),
SEC NRS (Russia),
SSTC NRS (Ukraine),
VTT (Finland),
VUJE (Slovakia),
Wood (United
Kingdom).
Revised version
of a paper presented
at the Eurosafe,
Paris, France, 6 and
7 November 2017.
13
ENERGY POLICY, ECONOMY AND LAW
Energy Policy, Economy and Law
ETSON Strategic Orientations on Research Activities. ETSON Research Group Activity
J.P. Van Dorsselaere, M. Barrachin, D. Millington, M. Adorni, M. Hrehor, F. Mascari, A. Schaffrath, I. Tiselj, E. Uspuras, Y. Yamamoto, D. Gumenyuk, N. Fedotova, O. Cronvall and P. Liska