It is important for safe operation of a nuclear reactor to accurately
predict nuclear reactions including neutron behavior. The Monte
Carlo method has become a powerful tool for this purpose due to
recent great advances of computers, especially supercomputers.
This method tracks the life of every neutron from its birth to
death in a reactor, a model of witch is accurately constructed
in a computer. If we track one to ten million neutrons, we can
very accurately predict the characteristics of a reactor. To realize
this capability we have developed new computer programs, GMVP
and MVP, which achieve the highest computation speed in the world.
Their speeds are 15 times faster than conventional programs. A
new algorithm called "stack driven zone selection method" was
developed to realize high-vectorization efficiency on vector supercomputers.
Those programs are now being used widely in many universities,
research institutes, and industries in Japan. Figure 6-7 shows
a cross section of the nuclear reactor ATR, a model constructed
by a computer. In conventional programs, it is difficult to treat
the complex geometry of a whole reactor. By developing a new method
to describe geometry, called "multiple lattice geometry", a reactor
model with very complex geometry can easily be constructed. Figure
6-8 shows research work necessary to develop those programs and
application fields. |
