Driving along Interstate 5, the San Onofre Nuclear Power Plant — SONGS for short — remains as majestic as ever from a distance.

However, this power plant that has not generated electricity for nine years is being demolished. A close visit to this 84-acre site can give you a glimpse of the content involved in such a large-scale operation.

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"There are years of planning and years of execution," said Amanda Wood, a waste manager for SONGS Decommissioning Solutions, the project's general contractor. "It's really about planning and coordination between all the different groups."

The truck kept whizzing past. The excavator lifts and moves the debris. On the east side of the factory, only rows of thick concrete walls remain in the four-story administrative building that has been used for decades as offices and meeting rooms. These walls rise vertically to meet the sloping soil above. They look like buildings that were bombed in World War II.

The decommissioning of SONGS is expected to take approximately eight years to complete and cost approximately US$4.5 billion. After completion, more than 1 billion pounds of equipment, components, steel, concrete, steel and titanium will be removed from the site. About 80% are considered radioactive.

By the time the demolition was completed, only a few structures remained.

Since the start of construction in 1968, Southern California Edison has been operating the plant, and the utility company hired a contractor to lead the demolition work. SONGS Decommissioning Solutions is a joint venture between Los Angeles engineering company AECOM and a Salt Lake City company called Energy Solutions, which specializes in nuclear material processing.

Edison obtained the necessary permits from the California Coastal Commission in October 2019, which cleared the way for demolition, and preliminary work began in early 2020. Since then, the pace of activities has accelerated and so far, 26 of the 62 buildings have been demolished.

According to an executive order signed by former Governor Gray Davis, all rubble from decommissioned nuclear power plants in California must be shipped out of the state.

Most of the debris in the factory is marked as Type A waste, which is the lowest level of radioactive material. Most of the rubble will be sent to a disposal facility in Clive, Utah-mainly by railcars, although some materials will be transported by trucks in barrels. Class B and C low-level radioactive waste was sent to a location near Andrews Township, West Texas. Non-radioactive materials entered Arizona.

"Even the e-waste we can usually recycle, we will ship to Arizona," said Jim Peattie, Edison's general manager in charge of retirement supervision.

He pointed to a large pile of crushed concrete near the southern end of the factory.

"This is all the gravel concrete pulled from all the different foundations," Peattie said. "They dismantled it and dismantled it, the excavator divided it into small pieces...they broke it down and removed the steel from it, and then put it in the crusher."

The crushed concrete is then loaded onto a rail car that can transport up to 200,000 pounds of material.

So far, more than 1,200 rail and truck transports have left the site, carrying 60 million pounds of waste. One railway line enters the factory line, and one line leaves the factory.

But as workers quickly dismantled the facility, workers are now laying additional tracks to speed up shipments. When they are completed, the seven lines will circulate within the perimeter of the factory.

"Our footprint here is so small, once we start producing this waste, it must go somewhere. We will run out of space," Wood said. "We have increased the railway capacity, so we can have about 50 rail cars on site at any time," and now there are only about 8 rail cars.

The additional capacity will increase the volume of rail transportation from 15 times a week to as many as 30 times a week.

Workers have begun to remove each reactor vessel from Unit 2 and Unit 3. Each container weighs more than 1 million pounds, is about 25 feet high, and has a diameter of about 16 feet.

Because the internal parts of the ship are close to nuclear fuel, they are classified as low-level radioactive waste. This means that the process of cutting and retrieving fragments is done underwater. To do this, each cavity is filled with approximately 500,000 gallons of treated demineralized water.

Remotely operated by the crew using underwater cameras, the components of the reactor vessel are pulled out one by one, and then cut into pieces with a rotating saw. Using robotic technology, these fragments are then taken out and placed in a container. The operation requires 12 to 20 crew members.

This sounds almost like science fiction, but the process has been used in other decommissioned nuclear power plants across the country, such as Zion in Illinois, the Connecticut Yankees in the northeast, and the Troy Nuclear Power Plant in Oregon.

The most notable feature of SONGS is the double containment domes of Units 2 and 3, each of which is 190 feet high, which can be clearly seen by the drivers on I-5, air pilots and sailors in the Pacific.

Once everything inside the dome has been removed, they will collapse—possibly around 2025.

But there will not be some dramatic implosion. On the contrary, the dome will gradually drop from bottom to top. Workers using hydraulic hammers will chop up a 160-foot-wide circle, and in stages, each dome will eventually collapse. The whole process takes about a year.

Ron Pontes said: "The contractor will bring the excavator and use a 6 or 8 foot lift to hit the side of the building until it becomes weak enough that it just falls down.", Southern California Edison decommissioned environment Strategy manager. "Then they will dig out all the concrete and steel. They will do this over and over again until the building slowly collapses."

After the work is completed, only some structure remains.

Most notable are the two dry storage facilities located at the northern end of SONGS, which contain spent fuel components-this highly radioactive material generates 2,200 megawatts of electricity when the plant is up and running, enough to generate approximately 140 MW at any time. Ten thousand families provide services in a timely manner.

One storage site contains 73 stainless steel waste tanks, which have been placed in protected vertical cavities. Another 50 are placed horizontally in another storage facility built many years ago. Another 25 tons of radioactive material from the demolition work will be placed in 12 horizontal tanks and transported to dry storage locations. The personnel in the security building will monitor all tanks.

The only other structures will be the 28-foot-high seawall, which was measured at the average low tide of St. Onofre Beach; a walkway connecting the two beaches of the factory north and south, and a switch station with electrical wires. The switchyard is a transformerless substation because it provides critical interconnection to the power grids that serve San Diego and Orange County.

Dry storage facilities have always been controversial. Some critics say that the jar is not thick enough to withstand cracking and degradation over time. Edison and the manufacturer of the tank insisted that they were safe and sturdy.

Why does the jar stay behind? This is not a problem unique to San Onofre.

Until the federal government fulfills its commitment to find waste repositories for commercial nuclear facilities, factories across the country will leave their spent fuel on site. According to the United States General Accounting Office, approximately 86,000 metric tons of spent fuel are accumulated in 75 operating or closed nuclear power plants in 33 states. SONGS has 3.55 million pounds of spent fuel in its storage facilities.

Completing such a complex project requires a lot of labor, coordination, and skill. Some critics doubt that Edison can complete such a large undertaking without major mistakes.

After all, it was a leak in the steam generator pipe in 2012 that caused SONGS to shut down.

In 2018, a 50-ton tank full of fuel assemblies was placed in a new dry storage facility and was suspended from a metal flange about 18 feet from the floor of its storage chamber, without the support of rigging and lifting equipment. The jar was eventually lowered safely, but the Nuclear Regulatory Commission later fined Edison US$116,000.

"Edison only promised to take a'commercially reasonable' approach to the nuclear waste stranded in St. Onofre," said Gary Hedrick, co-founder of the environmental group San Clemente Green, at the beginning of the demolition project. "Their current wishful thinking plan may work, but if not, like many other past examples you can point to?"

Pontes said that Edison "learned the lessons of the past" and took oversight measures to ensure that the contractor "carried out this work safely."

"We recognize that our reputation is threatened here," Pontes said. "I meet regularly with Edison's senior management, and they don't push for anything other than ensuring that we do things safely and correctly."

The approximately US$4.5 billion cost of dismantling SONGS came from the existing decommissioning trust fund. This money is collected from taxpayers and invested in a special trust fund. According to Edison, customers contributed about one-third of the trust fund, while the remaining two-thirds came from the company's investment returns.

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