Fast neutron transmission through auxiliary pipes near the surface of a pool type reactor

Using ray analysis method the fast neutron transmission through auxiliary piping of a swimming pool type research reactor core has been calculated. The results indicate that the fast neutron flux becomes negligibly small and at the height of 5 m above the core surface in the solid cylindrical aluminum support structure pipes and the control drive support pipes composed of stain less steel. It was also found that hollow aluminum guide pipe (generally used for neutron instrumentation) does allow substantial fast neutron leakage even up to 10 m away from the core. This leakage can be decreased to less than 0.06 n/cm/ sup 2/ sec if the guide pipe is more than 30 % filled with detector, cable and connector assembly. (author)