Photos from the Vault

Diablo Canyon reactor vessel installed

Feb. 1973,Diablo Canyon construction, Unit 1 was 64% complete and Unit 2 was 25% complete. Telegram-Tribune photo by Wayne Nicholls

Atomic energy was a growth industry in the 1960s. In San Luis Obispo County, nuclear electric plants were proposed on the Nipomo Dunes and near Cayucos before construction began at Diablo Canyon. The state was undergoing a dizzying growth cycle and utilities were moving to stay ahead of projected demand.

PG&E had wanted to build another atomic plant north of San Francisco in the early 1960s at scenic Bodega Head. They had bought property, negotiated rights of way for power lines and dug a big hole for a reactor vessel when they discovered the San Andreas Fault bisected the hole. The realization that this fault was responsible for the Great San Fransisco earthquake  gave the utility pause.

They made the most of a siting debacle by selling the property for use as a public park for $1. The hole would fill with rainwater creating a haven for birds and wags dubbed it the “Hole in the Head“.
Today a recently discovered fault is the subject of study in the water off of Diablo Canyon. Another, the Hosgri Fault would set back construction time tables at Diablo but that revelation had not yet surfaced when these photos were made.
Over 35 years ago construction was moving ahead.

February 15, 1973

Workmen at Diablo Canyon hover around a 345-ton reactor vessel as it begins a cautious journey to its final resting place.

Big reactor installed at Diablo

By Elliot Curry
Staff Writer
A 345-ton reactor vessel was rolled toward its permanent base at Diablo Canyon yesterday at the speed of a snail going uphill.
The steel reactor vessel,  43 feet high and 17 feet in diameter, will occupy a position at the very heart of the first unit of the PG&E nuclear-fueled power plant.
The move started yesterday is from the Diablo Canyon storage yard to an opening in the dome-shaped containment structure, most recognizable feature of the plant, which is one of the largest nuclear power sources under construction in the United States.
The reactor was loaded on the caterpillar running gears of a heavy crane from which the crane has been removed.
After the reactor is placed in the concrete and steel dome, it will be surrounded by four heat exchangers, often referred to as steam generators.
When the plant goes into operation, the reactor will contain 93 tons of slightly enriched uranium dioxide fuel pellets. Here the fission chain reaction takes place that provides the energy to heat the water that makes the steam that turns the turbines that produce electricity.
Unit 1 of the Diablo Canyon plant is now 64 percent complete and PG&E expects to be using power from the unit by 1975. Unit No. 2 is 25 percent complete.
There are about 1,500 employees at the Diablo plant, 2,000 employed by PG&E and 1,300 by 20 contractors. It is the third largest construction project ever built in California and PG&E now estimates the cost at $665 million.

I am still trying to make the next-to-last sentence make sense. My guess is it should read something like “There are about 3,500 employees at the Diablo plant, 2,000 employed by PG&E and the balance employed by 20 contractors.”
The rosy cost and completion projections would be changed by the public announcement of scientists discovering  the Hosgri fault later in 1973.
What were the first and second largest projects in the state alluded to in the article? Water projects? Freeways? The San Onofre Nuclear Power plant? A stadium? The story does not say.
With the expanded construction costs the plant could place higher on the list.
Unit 1 opened in November 1984 and Unit 2 in August 1985. Other posts about the plant construction can be found here.

Photos by Wayne Nicholls