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Regional Basic Professional Training Course in Korea

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❙ 271 ❙<br />

4. DESIGN OF NUCLEAR REACTORS<br />

4.2. RESEARCH AND TEST REACTORS<br />

4.2.1. Introduction<br />

S<strong>in</strong>ce the start‐up of the first nuclear reactor, carried out on 2 December 1942 by a team<br />

headed by Enrico Fermi at the University of Chicago, almost 600 critical assemblies and<br />

research and test reactors have been built world wide. Currently, there are 255 reactors <strong>in</strong><br />

service <strong>in</strong> 57 countries, and approximately 70% of these reactors are over 25 years old.<br />

Consequently, questions relat<strong>in</strong>g to the obsolescence and renovation of their equipment to<br />

take <strong>in</strong>to account changes <strong>in</strong> safety criteria are particularly pert<strong>in</strong>ent.<br />

The research and test reactors currently be<strong>in</strong>g operated have powers rang<strong>in</strong>g from 0 to<br />

250 MW (ATR reactor, Idaho, United States). Their designs, operat<strong>in</strong>g modes and uses<br />

differ greatly. These aspects are outl<strong>in</strong>ed <strong>in</strong> the follow<strong>in</strong>g section.<br />

4.2.2. Design considerations of research and test reactors<br />

4.2.2.1 Different types of research and test reactors<br />

Despite the fact that the design pr<strong>in</strong>ciples of research and test reactors are very different,<br />

two ma<strong>in</strong> categories can be identified: heavy water reactors (the heavy water is used as a<br />

moderator, coolant or reflector) and reactors moderated and cooled by light water.<br />

Heavy water reactors are used to produce <strong>in</strong>tense thermal neutron flux that are removed

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