Experimental and analytical techniques have been developed for delayed neutron (DN) signal analysis and characterization that can provide diagnostic information to augment data from cover-gas analyses in the detection and identification of breached elements in a liquid-metal fast breeder reactor. Eleven flow reduction tests have been run in Experimental Breeder Reactor II to provide base data support for predicting DN signal characteristics during exposed fuel operation. Results from the tests demonstrate the feasibility and practicability of response-analysis techniques for determining (a) the transit time, Ttr, for DN emitters traveling from the core to the detector, and (b) the isotopic holdup time, Th, of DN precursors in the fuel element. The value Ttr varies with the relative grid location of the DN source, and Th is affected by the form of fuel exposed to the coolant as well as the condition of the breach site. These parameters are incorporated into a mathematical formulism that enables one to compute for any exposed-fuel test an “equivalent recoil area.” This concept provides a basis for comparison of different run-beyond-cladding-breach tests in fast reactors.