Design of Nuclear Power Plants

[Lonny Eckert <LLE@nrc.gov>]

US commercial power plants are not comparible
to the Soviet-designed RBMK reactors.  The
differences between the designs are very
significant.

Dr. Cohen mentioned the fact that commercial
US reactors made many improvements after the
TMI accident.  The primary document which
you can gain more info in that regard is
NUREG-0737 and its supplement for those that
wish to delve further.

The most glaring design differences include:
1)  There is no containment over the RBMK
reactors as there are in ALL operating US
commercial power reactors.

2)  The RBMK reactors are carbon moderated
while the remaining operating US commercial
power reactors are water moderated.  A basic
explanation of the end result is that carbon
moderation leads to situations in which the
RBMK reactors can/will have an overall positive
reactivity coefficient.
  I don't want to get into a long dissertation of
reactivity coefficients for commercial US power
plants, but basically they maintain an overall
negative reactivity coefficent.

  Please refer any questions to me directly as
power plant designs and age of power plants is
somewhat of an off-topic.  Thanks.


Lonny Eckert
USNRC Region I
LLE@NRC.GOV

STANDARD DISCLAIMERS