Each weld and cladding have to undergo the stress relief annealing by a prescribed procedure: heating-up — dwell — cooling-down, so as to remove residual stresses in the material which attain up to the yield stress of the materia 1.Each section welded from two or more parts must be annealed: it must be kept in view that each annealing impairs material properties.

For the annealing. a furnace must be at disposal which enables placing in even a whole pressure vessel Dimensions of integral RPVs require very deep furnaces (more than 20m). (E. g. the annealing furnace at SKODA Reactor Shop has dimensions 7.5×7.5xl5ra which makes possible to anneal parts up to 13m long: pressure vessels VVER 440 and VVER 1000 are І1.8 and 10.8 long, respectively) In the last resort, a local annealing can be applіed.

Main machining operations are as follows­- turning of cylindrical surfaces of rings and welding edges,

— turning of spherical and/or eliptical surfaces of bottoms and covers including welding edges,

— boring holes and cutting threads in vessel flanges for flange bo1ts.

— boring holes in vessel covers for control-rod-drіve nozzles, instrumentation nozzles and flange bolts,

— machining of main nozzles and emergency-cooling nozzles including welding edges.

— machine or manual grindinq of outer and inner surfaces of vessels and covers, etc

A quality assurance programme must be followed during all phases of the manufacturing process a part of which is a programme of inspections and tests.

Main groups of Inspections and tests:

— material properties (chemical composition, structure,

mechanical properties, transition temperatuure curve etc.)

— geometry ( dimensions, shape, surface quality)

— integrity (surface integrity, volumetric integrity,

leak-tightness, strength).

Current techniques, apparatusses and devices which have been used at the manufacture of classic PVR and BVR pressure vessels are applicable for integral RPVs.

E. g.,« radiography of thick welds is performed by linear accelerators in special shielded cells. A heavy piece is transported to such a cell by a special truck with rotating positioners which have to have an appropriate loading capacity. At Skoda, the linear accelerator NEPTUN 10 MeV is used which is capable to test thicknesses up to 450 mm. A trolley rail-wagon with rotating positioners of 400 t loading capacity attends the testing cel 1.