Page 110 - Thermal Hydraulics Aspects of Liquid Metal Cooled Nuclear Reactors

P. 110

Design of experimental 3.2

liquid-metal facilities

M. Tarantino, I. Di Piazza, D. Martelli, D. Rozzia, R. Marinari, A. Pesetti, P. Lorusso
Experimental Engineering Division, Department for Fusion and Technologies for Nuclear
Safety and Security, ENEA, Brasimone (Bo), Italy

3.2.1 Introduction

Since the 1990s, main European research bodies and industries are deeply collaborat-
ing on a common view for the development of innovative nuclear systems cooled by
heavy liquid metal (HLM).
The common view was based on the need in developing innovative nuclear systems
aiming not only to supply energy but also at the same time to increase the sustainabil-
ity, the safety and reliability, and the proliferation resistance and physical protection
and to reduce the costs.
In this general context, radioactive waste management and reduction of radiotoxicity
are of paramount importance. One key element here is reducing the radiotoxicity of
plutonium and minor actinides, which constitute the most toxic, long-lived radioactive
components of the spent fuel, by transmutation into less radiotoxic isotopes.
Moreover, concerning the safety level, upgrading the nuclear power plants with
traditional-type reactors, in which potential energy is stored in large amounts
(Toshinsky et al., 2011), requires increasing the number of safety systems and
defense-in-depth barriers. It is clear that such measures can only reduce the probability
of severe accidents and mitigate the consequences, but cannot eliminate them when
there is large potential energy.
Reactors, whose potential energy is stored in the coolant, give rise to its release in
case of tightness failure in the primary circuit, and the subsequent destruction of pro-
tective barriers can lead to radioactivity release to the environment.
After the Fukushima nuclear accident, public opinion has been once more shocked
by the loss of control of a nuclear power plant. As a consequence, convincing dem-
onstration that future reactors can rule out catastrophic scenarios is necessary to
recover public acceptance.
At this point, it is thus needed
– to exploit to the maximum extent solutions that can deterministically exclude scenarios that
are potential initiators of accidents leading to severe core damage,
– to consider the possibility of managing extreme events in degraded plant conditions.

There is a reasonable expectation to demonstrate that lead fast reactors are able to
cover these two fundamental design objectives.

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