The VVER-1000 design was developed
between 1975 and 1985 based on the requirements of a new Soviet nuclear
standard that incorporated some international practices, particularly in
the area of plant safety.
Steel-lined, pre-stressed, large-volume concrete containment structure,
similar in function to Western nuclear plants.
"Evolutionary" design incorporating safety improvements over VVER-440
Model V213 plants. The Soviet approach to standardization was based on
continued use of components that had performed well in earlier plants.
Use of four coolant loops and horizontal steam generators--both
considered improvements by Soviet designers.
assemblies that allow better flow of coolant, and improved control rods.
Plant worker radiation levels reportedly lower than in many
Western plants, apparently due to selection of materials, high-capacity
system for purifying primary coolant, and water-chemistry control.
plant instrumentation and controls. Wiring of emergency electrical
system and reactor-protection system does not meet Western standards for
separation--control and safety functions are inter connected in ways
that may allow failure of a control system to prevent operation of a
Fire-protection systems that do not appear to
differ substantially from earlier VVER models, which do not meet Western
Quality-control, design and construction
significantly deficient by U.S. standards.
for control-room operators essentially unchanged from earlier VVER-440
Model V213 design, which does not meet U.S. standards. Unlike all U.S.
nuclear plants, and most in Western countries, VVER-1000s have no
on-site "technical support center" to serve as a command post for
stabilizing the plant in an emergency. Technical support centers were
incorporated in U.S. and many Western nuclear plants following the
accident at Three Mile Island Unit 2 in 1979.
emergency procedures that fall far short of Western standards and vary
greatly among opera tors of VVER-1000 plants.
densities and smaller volume of primary and secondary systems result in a
somewhat less forgiving and stable reactor.