Nuclear reactor start-up method
AssigneeHitachi, Ltd.
InventorsMotoaki Utamura, Yasuhiro Masuhara, Atsuo Yamanouchi, Koichi Kotani, Masanori Naitoh
Life of this patent
Estimating the term…
Abstract
A nuclear reactor start-up method of starting up a boiling water reactor which is in the cold shut-down state. The method includes setting a subcooled temperature of a coolant in a reactor core inlet to a range smaller than a critical subcooled temperature which is determined by the condition whereby the coolant starts boiling in the reactor core and the condition whereby the instability due to a periodic variation of buoyancy begins, thereafter starting an increase of power of the reactor.
Claims7
A method of starting up a boiling water nuclear reactor in a cold shut-down condition, comprising the steps of:
- i. forming a map of an output E-vs-subcooled temperature in accordance with the output E of the nuclear reactor core, and with the subcooled temperature .DELTA.T(P) of coolant at a reactor core inlet, which is a function of the pressure P of the coolant and which is determined by the following equation:
- .DELTA.T(P)=T.sub.B -T.sub.C ( 1)
- where T.sub.B is the boiling point of coolant under a predetermined pressure (saturation temperature), and
- T.sub.C is the actual temperature of the coolant under the predetermined pressure;
- ii. plotting outlet quality curves x(E, .DELTA.T) on the map which outlet quality curves are determined by the following equation on the map:
- x=m.sub.V /m.sub.T ( 2)
- where m.sub.V is the mass of vapor passing through the reactor core outlet per unit time, and
- m.sub.T is the total mass of coolant passing said through the reactor core outlet per unit time;
- iii. determining critical quality curves among a group of outlet quality curves on the map, the critical quality curves being obtained by the following equations:
- x(E, .DELTA.T)=x.sub.c1 ( 3)
- X(E, .DELTA.T)=x.sub.c2 ( 4)
- where x.sub.c1 >x.sub.c2,
- the critical guality curves defining boundaries along which first and second instabilities occur;
- iv. selecting one of the outlet quality curves, corresponding to a boiling initiation curve which is obtained from the following equation:
- x(E, .DELTA.T)=0 (5);
- v. determining a minimum subcooled temperature .DELTA.T'min which is crossing point between the boiling initiation curve of equation (5) and the critical quality curve of equation (4) relating to the second instability;
- and
- vi. starting increase of the output E of the nuclear reactor core from zero output at a point having a subcooled temperature of the coolant at the nuclear reactor core inlet which satisfies the following condition:
- .DELTA.T<.DELTA.T'min, between the critical quality curves of equation (3) and equation (4) on the map.
Dependencies are inferred from the claim text.