1. Contain core, reactor internals and the reactir coolant moderator
2. Serve as high integrity barrier against leakage of radioactive materials into the drywell
3. Provide for production of high quality saturated steam
4. Provide a floodable volume in which the reactor core can be adequately cooled in the event of a breach in the primary system external to the vessel

Steam quality at:

Inlet of steam separators,

Outlet of steam separators,

Outlet of steam dryer

Inlet steam seoarator = 14%

Outlet steam separator = 90%

Outlet of steam dryer = 99.9%

Why must the top of the Rx head be vented?

Where is it vented to?

Gamma radiation disassociates hydrogren and oxygen from water. The oxygen must be removed to prevent buildup.

The top of the head is vented to the "C" main steam line at power.

Moisture carryover is defined as moisture exiting the top of the steam separator at the top. This will overload the steam dryer and decrease the quality of steam leaving the reactor.

Problems with carryover: increase turbine wear, decrease turbine efficiency, increase radioactivity in plant

Carryunder is when steam exits the moisture separators along with the waterdrained from them.

Excessive carryunder will decrease NPSH to the recirc pumps, by heating the downcomer water. Also, reduces plant efficiency since steam is not sent to the turbine.

• Low pressure lines are tapped into the upper end of the diffuser section,
• High pressure sensing is from the pressure below the core plate - except for 4 high pressure "calibrated" taps in 4 jet pumps - located at the bottom end of the diffuser section.

How is the baffle plat supported?

What dows the baffle plate support?

• Supported by 6 columns that are welded directly to the bottom head
• Baffle plate supports:
• Jet pumps,
• Shroud and core spray sparger,
• Core plate,
• Top guide,
• PERIPHERAL FUEL BUNDLES