atw 2018-04v6

atw Vol. 63 (2018) | Issue 4 ı April
Experimental and Analytical Tools
for Safety Research of GEN IV Reactors
G. Mazzini, M. Kyncl, Alis Musa and M. Ruscak
Current research on nuclear safety in the world, in addition to supporting existing nuclear power plants (PLEX,
mitigation of severe accidents, the development of accident tolerant fuel, decommissioning, etc.), is focused on the
more detailed aspects of the new reactors. The new generation reactors are expected inter alia to use innovative types
of fuel and new types of coolants, such as e.g. Super-Critical Water (SCW), supercritical CO 2 , liquid metals, fluoride
salts or high-temperature Helium. The paper will describe new experimental infrastructure build recently in Research
Centre Řež under the SUSEN (Sustainable Energy) project and available analytical tools for supporting safety research
of GEN IV reactors. Two experimental loops - SCWL (Supercritical Water Loop) and HTHL (High Temperature Helium
Loop) will serve as in-pile loops in the active core of the research reactor LVR-15. The loops insertion in the reactor
LVR-15 requires performing additional safety analyses studying the mutual interference of the loops and the reactor,
especially in conditions of abnormal operation or accident conditions of the loops. The paper will provide examples of
these analyses made using codes ATHLET (supercritical water) and TRACE (high temperature He) illustrating process
of their assessment and practical use. These activities provide significant opportunity for TSO team in building its new
competencies.
Revised version
of a paper presented
at the Eurosafe,
Paris, France, 6 and
7 November 2017.
OPERATION AND NEW BUILD 221
1 Introduction
The Centrum Výzkumu Řež (CVŘ) and
its partners in the Czech Republic and
abroad are supporting the development
[1] of the Generation IV and
Fusion concepts as well as demonstrators
of these technologies such
as ALLEGRO, ALFRED, DEMO and
others. For this reason, the CVŘ has
had a large R&D program financed
from SUStainable Energy (SUSEN)
project and from its continuation
Research 4 Sustenibility (R4S) [2].
The construction and the operation of
the new SUSEN infrastructure was
supported by the grant of the Ministry
of Education, Youth and Sports as the
part of state help for the large research
infrastructure in the Czech Republic
dedicated to the period 2011–2019.
The SUSEN project consists of 4
programs:
1. Technological Experimental Circuits
(TEO)
2. Structural and System Diagnostics
(SSD)
3. Nuclear Fuel Cycle (NFC)
4. Material Research (MAT)
Within this program, several facilities
were designed and built in order to
study and to address new challenges
of such new technologies. In particular,
the paper focuses on two new
loops which are going to be inserted
inside the LVR-15 research reactor
existing in Řež. The LVR-15 is a light
water tank-type research reactor in
operation since 1957. It is placed in a
stainless steel vessel under a shielding
cover, has forced cooling, uses IRT-4M
type fuel and an has an operational
power level of 10 MWt. The reactor
operations run in campaigns that
usually last for 3 weeks, followed by
an outage lasting for 10 to 14 days
necessary for maintenance and fuel
reloading. There can be also other
campaigns which can operate for
‘short-time’ experiments. Some of the
LVR-15 applications are in the field of
material irradiation research and services,
neutron physics, development
and production of new radiopharmaceuticals
[3]. The loops in concern are
the High Temperature Helium Loop
(HTHL) and the Super Critical Water
Loop (SCWL) and their main scope
are to analyse the cladding behaviour
and structural materials under different
pressure, temperature and coolant
media conditions different from the
standard Light Water Reactors (LWR)
technology [2].
In order to get the regulatory
permit for in-pile operation of these
loops in LVR-15, CVŘ has to prepare
an amendment to the Final Safety
Analyses Report (FSAR) containing
safety analyse of the loops under
| | Fig. 1.
CVR Facilities list.
operational and accidental conditions.
Aim of this paper is to present
the methodology and the analyses
done in support of this process, starting
from code benchmarking/assessment
and the methods adopted in preparing
the safety case.
2 Facilities description
The map of experimental facilities put
into operation in 2016 and those
under preparation to be finalized in
2017 is shown in Figure 1 in the
technology – knowledge map.
In particular, the SCWL and HTHL
represent a pioneer and unique experimental
facility for Gen. IV and Fusion.
2.1 SCWL
The SCWL is going to be a part of a
research facility dedicated to GIV
technologies which will focus on
obtaining data in several areas of the
supercritical fields like: corrosion
processes of construction materials in
supercritical water, with influence of
Operation and New Build
Experimental and Analytical Tools for Safety Research of GEN IV Reactors ı G. Mazzini, M. Kyncl, Alis Musa and M. Ruscak