The Shift of Prompt Critical in Reflected Reactors and the Limitations of the Mean Prompt-Neutron Lifetime Model

Conference · Sun Nov 13 04:00:00 EST 1994

OSTI ID:10171239

Spriggs, G. D. ^[1]; Busch, R. D. ^[2]

---

1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
2. University of New Mexico, Albuquerque, NM (United States)

Prompt critical in a bare reactor is defined as the point at which the reactivity Ρ of the reactor is equal to the effective delayed neutron fraction Β. In a reflected reactor, however, it is shown that prompt critical will occur at a reactivity of Ρ = Β(1-f) where f is the fraction of core neutrons that return to the core region after having leaked into the reflector. Furthermore, it is also shown that the mean prompt-neutron lifetime model that has been traditionally used to characterize the dynamic response of reflected reactors may not always provide an adequate representation of the system for reactivities greater than 1$. And finally, the coupled, point-kinetic equations proposed by Avery and further developed by Cohn for simple reflected systems are recast into a more usable form that can be readily used to perform superprompt critical transient analyses.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); University of New Mexico, Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 10171239
• Report Number(s): LA-UR--94-2250; CONF-941102--18; ON: DE94016078
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220100
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Bare Reactor
CRITICALITY
DELAYED NEUTRONS
Nuclear Criticality Safety Program (NCSP)
PROMPT NEUTRONS
PULSED REACTORS
Prompt Critical
REACTIVITY
THEORY AND CALCULATION