Palo Verde Nuclear Generating Station

Palo Verde - Arizona

Palo Verde Nuclear Generating Station is the largest nuclear electric generating site in the United States. Three (3) Combustion Engineering Pressurized Water Reactor units each have an output of ~ 1270 MWe. Each unit has 2 reactor cooling loops, each with a 2 reactor cooling pump and a single steam generator. Arizona Public Service Company is the operator and co-owns the units with utilities in New Mexico, Texas, and California. The Palo Vede site is at Wintersberg, Arizona, 34 miles west of Phoenix. Units 1 and 2 went commercial in 1986 and Unit 3 in 1988.

Courtesy Nuclear Power Engineering

A number of simplified diagrams illustrate the the design of this pressurized water reactor plant. Although this diagrams were provided by Westinghouse, they are representative of the Combustion Engineering design.

Each Palo Verde unit has a metal containment designed for 60 psig.

The reactor contains 241 fuel assemblies of the 16x16 design with 236 fuel rods per assembly. Normal reactor coolant makeup is provided by 1 of 3 Chemical and Volume Control charging pumps rated at 44 gpm @ 2735 psid

Emergency Equipment includes:

High Pressure Safety Injection consisting of 2 pumps rated at 815 gpm @ 1230 psia with a shutoff head of 1860 psia. Borated water is supplied from the Refueling Water Tank.
Low Head (Safety) Injection System (LHI) consisting of 2 pumps rated at 4200 gpm @ 145 psia with a shutoff head of 205 psid. (these pumps double as residual heat removal pumps)
Auxiliary Feedwater System consisting of two 100% motor driven pumps and one 200% turbine driven pump. These take a suction from a 550,000 gal Condensate Storage Tank or 420,000 gallon Reactor Makeup Tank.
2 Diesel Generators per unit with 2MWe gas turbine generators which are shared with other units on the site.
Ultimate heat sink - Supply to ECCS Service Water System: Essential Spray Cooling Pond

Emergency Borated Water Sources are:

Refueling Water Tank----------750,000 gal
Four Safety Injection Tanks (Accumulators) --72,000 gal
Spent Fuel Pool (Emergency Boration Source)

Normal condensate-feedwater to the steam generators is provided by 3 condensate pumps (535 psig shutoff head) which supply 2 steam-driven feedwater pumps, Unique to this plant is a separate startup feedwater pump for each unit. Also unique is the re-use of water from the Phoenix Municipal Waste Treatment System, which is processed, treated, and stored in an ultimate heat sink water supply lake onsite. Cooling Towers are used for cooling water heated in the condenser.

For detailed information, refer to the NRC Plant Information Books for Palo Verde 1 / 2 / 3