POWER EXCURSIONS IN THE HRT

Technical Report · Mon Feb 29 04:00:00 EST 1960

OSTI ID:4190978

Rosenthal, M W; Jaye, S; Tobias, M

During periods when the Homogeneous Reactor Test (HRT) has been operated at power, power "excursions" were observed to occur at a rate which averaged about two per hour. The occurrence of an excursion is indicated by a change in the output of the compensated ion chamber and confirmed by the response of other variables which are sensitive to power level. Excursions were observed rarely at initial core powers lower than 1 Mw; however, above power level. Excursions in which the power decreased also occured, but at a much lower frequency, and there appears to be little correlation with power level. The power in most of the excursions rose less than 50% above its initial value, although on three occasions it increased between 100 and Mw in about 8 sec. The amount of energy generated during an excursion was never so great that there was a significant pressure surge. The characteristics of the excursions suggest that they result from movement of uranium within the core, and their behavior is consistent with that of the uranium precipitation that is known to occur in the reactor. In addition to the excursions, the HRT power was found to undergo continuous "fluctuations" in which the power generally changed less than 3%, the average fluctuation size being less than 1%. The fluctuation frequency was in the range of 8 to 16 per minute. The source of the power fluctuations has not been determined, but several differences between their characteristics and those of the excursions suggest that they are not caused by the same phenomenon. A method used for estimating the reactivity associated with an excursion is described, and calculated reactivities which would correspond to various physical occurrences in the reactor are given. (auth)

• Research Organization: Oak Ridge National Lab., Tenn.
• DOE Contract Number: W-7405-ENG-26
• NSA Number: NSA-14-009245
• OSTI ID: 4190978
• Report Number(s): ORNL-2798
• Country of Publication: United States
• Language: English

Related Subjects

EXCURSIONS
HOMOGENEOUS REACTORS
HRT
IONIZATION CHAMBERS
MONITORING
POWER
PRECIPITATION
REACTOR TECHNOLOGY
RESEARCH REACTORS
URANIUM
VARIATIONS