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Startup of the OPEN100 typically will only involve transitioning from a cold shutdown mode. The initial point of this startup is described by the BOP island is being shut down and the RCS temperature is maintained around 150 degF by utilizing the RHR pumps in lieu of the RCS pumps. A neutron source may be added to create initial reactivity. This is the standard startup procedure utilized after a reactor replacement outage and after any possible emergency shutdown.

Normal Op Loop
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Normal Operation

Normal Operation will involve the NSSS systems operating at a full load power status in a base loaded manner. Design intent is to operate the OPEN100 reactor at a base load condition and the plant operator modulates loads per grid requirements by routing steam around the turbine, or "bypassing" the steam turbine, to the condenser. A constant reactor load permits the plant to operate in its most stable and reliable manner while bypassing steam allows the plant to respond to changing grid requirements.



Shutdown will normally occur only during reactor replacement operations once the core has reached its limit for being able to produce the plants rated thermal output. Due to a single-batch long fuel cycle design (>36 months), reactor shutdown is anticipated once every several years. Unscheduled shutdowns can be performed by shutting down the reactor but are avoided whenever possible. Steam turbine bypass mode may be used to shutdown the production of electricity while allowing the reactor to continue to operate in the normal design condition.



With systems critical to plant operation employing redundant equipment, routine maintenance is generally not needed during a normal fuel cycle. In the event that a major component is inoperable in the turbine or auxiliary buildings, maintenance can be scheduled to repair the equipment and return it to service without disrupting normal plant operation. Other, more routine, maintenance will be scheduled based on data collected by the control system and executed during the reactor replacement outage.

Full Load Rejection

Full Load Rejection Capabilities

Full load rejection can occur when a disruption in the distribution grid affects the plants ability to export its power. If the generator is tripped off line and the load is reduced to only include plant auxiliaries, the bypass of steam to the condenser will allow the NSSS Island to continue operating normally with the diesel generator providing essential services power. This allows the plant operators can assess the extent of the disruption and respond in a more measured manner.

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Plant Emergency Response
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Plant Emergency Response

In the event that the Nuclear Safety Systems do initiate a reactor trip signal, control drums or rods will be actuated to terminate the reaction. The steam turbine will also be dropped out of service and power will be imported from off-site for operation of the RCS pumps and key BOP pumps. As decay heat is spent by the steam generator’s continued production of steam, the pressure in the RCS will decay to allow the RHR system to be placed in service and maintain the reactor in a safe mode. Backup diesel generators are available if grid power is lost.

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