Weeks after the stunning decision by Southern California Edison to close down their failed San Onofre Nuclear Generating Station (SONGS), activist Ace Hoffman has pieced together why he and his fellow community leaders were able to shut down SONGs.
It turns out that SCE got greedy. Read on for Hoffman’s very astute analysis of how SONGS was shut down:
From: Ace Hoffman <firstname.lastname@example.org>
Date: June 20, 2013, 9:12:07 PM PDT
Subject: How “David” Slew “Goliath” (i.e., How the Activists Shut Down San Onofre)
“Oh no, it wasn’t the airplanes. It was beauty killed the beast.”
The glitter of gold attracted the operators of the San Onofre Nuclear Generating Station. It did them in.
Faced with the need to upgrade an old design, SoCal Edison demanded of Mitsubishi (the contractor for the replacement steam generators) too many impossible and conflicting constraints.
Most Pressurized Water Reactors (PWRs) have three or four steam generators which, as the name implies, convert water to steam. San Onofre’s reactors have only two steam generators each, so if one fails, the other has to handle the full task of cooling the reactor. This was one of many design flaws, but they had lived with it. The problem came when they tried to get even more output from the replacement steam generators, despite using a new, more corrosion-resistant alloy that was 10% less heat conductive than the original alloy.
They made up for the 10% loss of heat transfer capabilities by adding hundreds more tubes in the same space, packing them all closer together, and increasing their length by an average of about 50 inches. Additional changes were made as well, usually to prevent corrosion-related problems that had plagued the original steam generators. These changes may or may not have been successful — we’ll never know because somewhere along the line, they completely miscalculated how much steam would be produced inside the steam generators. Outside the tubes (but inside the steam generator casing) there was supposed to be about 96% steam and 4% water. Instead it was over 99% steam, which allowed the tubes to vibrate. The flow rate was much higher than expected, which also caused, or increased, the vibration.
The damage could probably have been prevented by operating the steam loop at a higher pressure, combined with a higher circulation ratio. (The circulation ratio indicates the number of times the water goes around the steam generator before becoming steam, and should be close to five or more, but it was less than four in the SanO SGs.). Adjusting these factors would have meant less steam production — and less profit. But it might have saved the reactors.
The glitter of gold got them.
How greedy was SCE? Extremely! About a decade ago, they applied for, and received, a power uprate which allowed them to operate the original steam generators (and later, the replacement steam generators) at higher temperatures and flow rates in order to produce significantly more steam — “pure” profit. The only problem was that doing so accelerated corrosion and fatigue wear in the original steam generators.
Or WAS that a problem, in their view?
Perhaps not, because they planned to bilk the ratepayers for the full cost of the replacement steam generators. And the sooner that happened the better, as far as the utility was concerned.
What they wanted to avoid was to be replacing the steam generators around the time of the next license renewal, in 2022. Accelerated wear followed by an early replacement suited them just fine: That way, they could expect to slide through the license renewal with a “like-new” pair of reactors that they planned to claim was all ready to go for the next 20 or even 40 years. Never mind the waste problem they were continuing to create for everyone, and never mind all the other components that were also wearing out.
SCE delayed some plant upgrades, and separated out the cost of a few items (such as new reactor pressure vessel heads, new turbine blades, miles of new pipes, new control equipment, etc.) to keep the cost of replacing the steam generators themselves below a billion dollars. Thus they were able to appease some activists who complained only about the cost. (Moral: Never complain only about the cost.) The Nuclear Regulatory Commission approved the uprate, and the California Public Utilities Commission approved having the ratepayers pay for it, and SCE turned up the steam output, and the power, and the profits, and shortly thereafter, ordered four replacement steam generators from Mitsubishi.
With the new steam generators installed, the license extensions were expected to be a breeze. The NRC had never denied a license extension and still hasn’t.
Then Fukushima happened, and the opposition to San Onofre in the community swelled. American ex-pats came back from Japan to California with their young families, with terrifying stories about the incredibly poor way the Japanese government and many of the Japanese people are handling the radiation crises over there. Highly radioactive rice and vegetables are being downblended with less radioactive products to reduce the dose to “acceptable” levels. Radioactive food is being exported to poor countries as “aid” supplies. Radioactive waste is being shipped around Japan only to be burned (and thus released to the environment) in cities far from Fukushima. And worst of all: Thyroid abnormalities are suddenly rampant among Japanese children and there are rumors of excess numbers of stillbirths and deformed babies that can’t survive, of doctors being told not to say anything to the parents — to just say the baby was born dead.
These returning ex-pats did not want the same thing to happen here. And much of it WILL happen if we have a nuclear disaster.
Less than a year after Fukushima, and less than two years after San Onofre’s new steam generators were installed, with opposition to San Onofre in full swing, one tube inside one steam generator leaked. Nearly 40,000 tubes had been replaced, but just one leaky tube spelled doom for San Onofre. They had been hit right between the eyes.
At first, the operators of the plant didn’t — or couldn’t — believe anything serious had happened. So one tube leaked? They called it “settling in.”
But then they looked more closely, and the real problem began to reveal itself. This wasn’t just teething pains. The steam generators had vibrated excessively, and thousands of tubes had rubbed against tube supports and against other tubes. There was 90% through-wall wear in one tube in Unit 2, which had been shut down for the first refueling after its steam generator replacement, and more than 90% through-wall wear in numerous tubes in Unit 3, with one, — the one that leaked –, at 100% through-wall wear.