Page 429 - Fundamentals of Magnetic Thermonuclear Reactor Design

Safety of Fusion Reactors Chapter | 14 407

14.3.2 Radiation Protection Principles
Apart from setting individual dose limits (the limits setting principle), the fusion
reactor radiation safety imperative requires that a few other safety standards are
followed, including the following:
The substantiation expediency principle: social benefits from a given facil-
ity must be higher than the possible maximum risks associated with harmful
and hazardous factors to people and the environment (minimisation of the risk-
benefit ratio).
The optimisation principle: the impact of ionising radiation on population,
personnel and the environment in all operational states must be as small as rea-
sonably achievable using economic and social criteria. One possible criterion
for justifying radiation protection costs is the assumption that ‘a collective ef-
fective dose of 1 man-Sv entails potential damage equal to a one man-year loss
of human life’ (NRB-99/2009). This damage is equivalent to at least annual
gross national product per capita [9].
The defence in depth protection principle: the idea of this principle is to pro-
vide multiple barriers preventing the release of ionising radiation and RSs to the
environment and using organisational and technical safety measures structured
into five levels (Fig. 14.1) [5]:
Level 1
l Well-grounded choice of site to accommodate the reactor and the controlled
area.
l Prevention of abnormal operation and failures (incidents).
l Project robustness achieved by means of conservative design and utmost
use of intrinsic self-protection capabilities, proven technologies and certi-
fied computational models and methods.
l Assurance of high quality in reactor design, construction and operation.
l Strict compliance with regulatory documents, technological regulations and
operating instructions.

FIGURE 14.1 Organisational and technical fusion safety measures.