Selective Use and Location of Materials

The Ideas within this group of suggestions are based on keeping the activated concrete as free as possible of materials which are difficult to remove, either because of their tendency to become and remain radioactive for long periods or because of their physical properties and degree of bond with the concrete. The methods that have been considered are summarised below. 

For reasons that have been already stated, the presence of steel, including reinforcement and prestressing tendons, within the activated zone Is a severe disadvantage from the point of view of decommissioning. 

The Heysham II/Torness PCRV design does not contain significant reinforcement close to the reactor cavity. The prestressing tendons. In solid wall steel ducts, are a minimum of 0.5m away from the main liner and are therefore outside the likely activated zone. See figure 6. 

Keep reinforcement and prestressing tendons In discrete regions of the activated zone to localise problems due to activated steel. 

PCRVs are axlsymmetrlc structures with an essentially axlsymmetrlc stress distribution and reinforcement and prestressing tendons must accordingly be regularly spaced out. 

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