Control valve station steam

The downstream pressure-sensing pipe of each valve is connected to a straight section of pipe 10 diameters or 1 meter downstream of the nearest tee, elbow or valve. This sensing line should be pitched down, to drain into the low-pressure line. If it cannot drain when connected to the top of this line it can often be connected instead to the side of the pipe. The pipe between the two control valves must be drained through a steam trap, just as would the foot of any riser downstream of the pressure-reducing station. 

Installation of a position indicator of the control valve of the steam line in the measurement control station. 

Snuffing steam, which is used to suppress a fire in the header box in the convection or radiant sections, is supplied through local and remote manifolds. The remote manifold shoulintermediate pipe support column. If the local area is unreadi-able in an emergency, steam would be supplied from the remote manifold. The inlet and outlet control stations are located along the pipe rack adjacent to die furnace. This particular fiimat uses manually controlled valves for each burner. The burner supply headers—fuel gas, fire steam, and fuel oil—are run... 

The fact that the throttle-valve position can change with frequency does complicate the control problem somewhat,. Should frequency fall, more power is needed to restore it. But opening the throttle valve does not produce more power. So if steam pressure is to be maintained, the firing rate must be made to vary with frequency. To accomplish this, a frequency-deviation signal is usually added to the output of the set station where the desired power output is introduced. 

The fourth functional event SGI-SBO represents the secondary side integrity functional event. The reference PSA model (Bertucio et al., 1990) assumes inoperability of the atmospheric relief valves during station blackout due to the unavailability of control power. It is assumed that the safety valves will conduct the steam relief Uncon-troll depressurization is implicated by the safety valves failure to reclose. This jeopardizes the steam generators integrity. 

At about 120 min (2 h), a conference phone call began between the control-room technical superintendent and (at their homes) the station superintendent, the vice president of generation, and the Babcock Wilcox site representative. The conference call lasted 38 min. Conferees realized that something was abnormal since the reactor coolant pumps were off yet they were unable to get a steam bubble in the pressurizer. The blown out rupture disk on the reactor coolant drain tank and the water on the reactor building floor did not seem surprising, since this had happened before. The condition of the block valve upstream of the PORV was questioned. It was reported to be shut, but it was not. The conferees decided to restart a reactor coolant pump, and all officials planned to report to the control room. 

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