SELF-LIMITING EXCURSION TESTS OF A HIGHLY ENRICHED PLATE-TYPE D20-MODERATED REACTOR PART II EFFECT OF SYSTEM PRESSURE

摘要

Self-limiting power excursion tests have been conducted to investigate the effects of initial system pressure on the dynamic response of the Spert II BD-22/24 Expanded D20 Core. This D2O-moderated core is comprised of 3-inch square x 24-inch long, highly enriched, uranium-aluminum, plate-type fuel assemblies spaced on 6-inch centers. The power excursions were initiated by stepwise reactivity insertions at ambient temperature, with no forced coolant flow, at various initial system pressures from atmospheric to 375 psig, and both with and without an expansion space in the reactor vessel. These tests demonstrated that the delay or suppression of boiling brought about by an increase in the system pressure results in higher maximum powers, energy releases, and fuel plate temperatures for those short period tests in which steam formation is an important contributor to shutdown at atmospheric pressure.