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The equivalent fundamental-mode source

Technical Report ·
DOI:https://doi.org/10.2172/464158· OSTI ID:464158
 [1];  [2]; ;  [3]
  1. Univ. of New Mexico, Albuquerque, NM (United States)
  2. Los Alamos National Lab., NM (United States)
  3. Japan Atomic Research Institute, Tokai (Japan)
In 1960, Hansen analyzed the problem of assembling fissionable material in the presence of a weak neutron source. Using point kinetics, he defined the weak source condition and analyzed the consequences of delayed initiation during ramp reactivity additions. Although not clearly stated in Hansen`s work, the neutron source strength that appears in the weak source condition corresponds to the equivalent fundamental-mode source. In this work, we describe the concept of an equivalent fundamental-mode source and we derive a deterministic expression for a factor, g*, that converts any arbitrary source distribution to an equivalent fundamental-mode source. We also demonstrate a simplified method for calculating g* in subcritical systems. And finally, we present a new experimental method that can be employed to measure the equivalent fundamental-mode source strength in a multiplying assembly. We demonstrate the method on the zero-power, XIX-1 assembly at the Fast Critical Assembly (FCA) Facility, Japan Atomic Energy Research Institute (JAERI).
Research Organization:
Los Alamos National Lab., NM (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States); USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
DOE Contract Number:
W-7405-ENG-36
OSTI ID:
464158
Report Number(s):
LA--13253; ON: DE97005284
Country of Publication:
United States
Language:
English

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