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Response to Severe Changes of Load on the Reactor System of Nuclear Ship Mutsu

1993; Taylor & Francis; Volume: 30; Issue: 2 Linguagem: Inglês

10.1080/18811248.1993.9734460

1881-1248

Toshihisa Ishida, Tsuyoshi Kusunoki, Masa-aki Ochiai, Yoshimi Tanaka, Toshiaki Yao, Kimio Inoue,

Nuclear and radioactivity studies

Abstract The response of the nuclear power system of N.S. Mutsu to severe changes of load have been studied from records taken during the power-raising tests performed on the ship in 1990. The records examined were those involving the most severe load changes foreseen for marine reactors : (a) sharp load increase with total steam flow raised from 25 to 70% rated full flow in 13 s, (b) crash astern maneuver with the position of propulsion turbine command handle changed—taking several seconds—from cruising ahead to STOP, and after about 50 s, further changed—taking 30 s—to bring the astern propulsion turbine to full speed—to consume approximately 60% rated total steam flow and (c) turbine trip with the ahead turbine intentionally tripped when operating at roughly 100% rated total steam flow. The foregoing records from load changes—of severity beyond what is foreseen for land- based reactors—proved that the Mutsu reactor is capable of responding smoothly and securely to such severe load changes. These load changes occasioned relatively large mismatches between reactor power supply and steam flow demand, but with notable freedom from any conspicuous overshooting or hunting of the reactor power. This performance can be attributed to (a) correct functioning of the automatic power control system, (b) effective contribution of the self-regulating reactor control property deriving from the large negative feedback between moderator temperature and reactivity, and (c) the ample inventories of coolant in the primary and secondary loops. The responses to load change are discussed covering those relevant to (a) reactor power, (b) primary loop pressure, and (c) steam generator pressure, with particular reference to the differences seen in response to mild and to severe load changes. KEYWORDS: Mutsu reactorresponse functionspower-raising testload changeload increasecrash asternturbine tripautomatic control