1987 Fiscal Year Final Research Report Summary
Basic Experiments on Criticality Safety with Data Processing Based on Stochastic Process Theory
Project/Area Number 
60460233

Research Category 
GrantinAid for General Scientific Research (B)

Allocation Type  Singleyear Grants 
Research Field 
Nuclear engineering

Research Institution  Nagoya University 
Principal Investigator 
NISHINA Koujirou School of Engineering, Nagoya University Professor, 工学部, 教授 (60023222)

CoInvestigator(Kenkyūbuntansha) 
小林 岩夫 日本原子力研究所, 燃料安全工学部臨界安全研究室, 室長
YAMANE Yoshihiro School of Engineering, Nagoya University Assistant Professor, 工学部, 講師 (60115649)
KOBAYASHI Iwao Japan Atomic Energy Research Institute Division of Fuel Safety Engineering Head

Project Period (FY) 
1985 – 1987

Keywords  Noise analysis / Reactor fuel / Criticality safety / Californium / Power spectrum / Stochastic process / Subcriticality / 中性子増倍モニター 
Research Abstract 
In this project the possibility of using the Cfneutronsource noise method as a criticality safety monitor in plant environment is investigated. Therr detectors are used.one ionization chamber containing a Cf source. and two neutron detectors. A ratio called "spectral ratio" is evaluated from therr crosspower of the detector outputs and autopower spectrum of the Cf detector. By stochastic process theory this ratio is related to the neutron multiplication factor which is the quantity of out interest. The following progress was made during the present period of the project: (1) A theoretical formula was derived which predicts the apparent dependence of the spectral ratio. and hence neutron multiplication factor, on the locations of the three detectors. (2) This formula was verified experimentally,although the numder of experimental points are seill limited. (3) With a Monte Carlo code programmed. the formula described in (1) was verified for a modeled system. (4) With this code. the dependence of the specral ratio on the Cf source intensity was verified to be weak. (5) To adapt this moise method to a twounit system, a formula expressing the depencdence of spectral ratio on the unit distance was derived based on twopoint kinetic formula. (6) A rigorous formula was derived including the effect of delayed neutron. which which relates the spectral ratio to the neutron multiplication factor. The conventional neglection of delayed neutron turned out to be legitimate.

Research Products
(4 results)