Solid Radioactive Waste Strategy Report.pdf - UK EPR

EPR UK
N° NESH-G/2008/en/0123
REV. A PAGE 99 / 257
· Various cutting techniques will be available to size reduce equipment. The most
appropriate technique will be applied depending on specific physical characteristics of the
piece (size, thickness, type of material) and intervention principles. The following can be
used:
o Steam generators: thermal (plasma, torch), mechanical (circular saw, band saw);
o Reactor coolant pump: thermal (plasma, torch), mechanical;
o Main Coolant Pipe: thermal (plasma), mechanical (tool used for SG replacement);
o Pressuriser: thermal (torch);
o Reactor pressure vessel internals: thermal (plasma), mechanical (circular or band
saw), abrasive water jet;
o Pressure vessel / pressure vessel head: thermal (plasma), mechanical (circular
saw);
o Reactor pit concrete: diamond wires and core boring tools, circular saw;
o Reactor pressure vessel supporting ring: circular saw.
· Decontamination techniques:
o
o
Full decontamination process is scheduled for the primary circuit, using a process
such as CORD-UV. The process will be performed on the intact primary circuit
after defuelling. The CORD-UV process allows:
· the oxidation to carbon dioxide by means of UV (ultraviolet light) of the
organic chemicals that are used;
· the completion of the entire decontamination with only one fill of water as
the circulation water is cleaned by ion exchange;
· the removal of the oxide layers present and a controlled dissolution of a
layer of base metal material;
· The cycle sequence of the decontamination (pre-oxidation, reduction,
decontamination, chemical decontamination) may be repeated until the
activity is removed and fixed on ion exchange resins;
· The use of UV wet oxidation and ion exchange minimises the amount of
secondary waste produced.
Item specific decontamination will be performed in a workshop to allow some
reclassification and even recycling or controlled clearance for disposal (on a case
by case basis).
This baseline can be adapted to include additional options such as:
1. Removal of components (reactor pressure vessel, steam generator) in one piece as
demonstrated with various projects worldwide. This may:
· Reduce operations and need of auxiliary installations;
· Reduce duration of the decommissioning;
· Allow recycling of the reactor component materials to fabricate waste containers to
minimise volume for disposal.
2. The steam generators may be fully dismantled and packaged within the reactor
containment building.