NEUTRON DIFFUSION IN REACTORS WITH LARGE HOLES

Technical Report · Mon Aug 01 04:00:00 EDT 1955

OSTI ID:4331267

Hassitt, A

In a reactor containing a cavity, the neutrons diIfuse in the material, but stresm in straight lines across the hole. The conditions on the boundary of the hole are not easy to deal with. The flux at any point depends on the flux at every other point on the surface of the hole. An iterative method of satisfying these boundary conditions, in the spherical harmonics P/sub 1/ approximation, is examined. The iteration is started by taking the flux to be constant on the surface of the hole. The diffusion equations are solved numerically, and a new value of the flux at each point is calculated, by computing the number of neutrons streaming across from all other points on the surface of the hole The diffusion equations are solved agsin with the new values of the flux on the hole surface. and the whole process is repeated. The necessary, but not sufficient, condition no neutrons created or absorbed in the hole'' is satisfied at each stage of the iteration. A slmple example of a bare cylindrical reactor, with an enclosed cylindrical cavity, is considered. The iterative process appears to converge after three iterations. Applications of the method to more elaborate svstems are being considered, and the conditions for the validity of the P/sub 1/ approximation are being examined. (auth)

• Research Organization: United Kingdom Atomic Energy Authority. Research Group. Atomic Energy Research Establishment. Harwell, Berks, England
• NSA Number: NSA-12-008710
• OSTI ID: 4331267
• Report Number(s): AERE-T/R-1692
• Country of Publication: United Kingdom
• Language: English

Related Subjects

BEAMS
CONFIGURATION
CYLINDERS
DIFFUSION
EQUATIONS
NEUTRON BEAMS
NEUTRON FLUX
NEUTRONS
NUMERICALS
PHYSICS
REACTOR CORE
REACTORS
SURFACES
ZONES