Tuesday, August 30, 2022

Extending Diablo Canyon's operating license: A fiasco waiting to happen...

August 30, 2022

Dear Readers,

Extending Diablo Canyon's operating license is a violation of carefully debated and long-established agreements to close the reactors after their design life of 40 years.

Rusted and age-worn parts are a pervasive problem at the aging plant. Numerous large structures would have to be replaced to last another 20 or 40 -- or 60??? years. And since shutdown in the next few years was an accepted and anticipated event, many parts are only being replaced if they fail (known as a "fix on fail" policy). These parts are assumed to not be "mission-critical" but not all multiple- or cascading parts failures have been evaluated. There are literally thousands of accident scenarios that are far more likely because so many parts are being neglected.

Worker shortages plague the facility, and knowledgeable employees are being paid enormous bonuses to convince them to stay until the planned closure in the next few years. After nearly 40 years of operation, there is probably not a single employee left at the plant who actually helped build the plant, and none of the design engineers are available to confer with if there is a problem. In short, no one really knows how the plant works. Seriously!

But that's only a few thousand good reasons to close Diablo Canyon today, rather than over the next couple of years, let alone, 20+ years from now (or will it be 40+ years, or 60+...or more?).

California has a state law that new reactors cannot be built until and unless there is an out-of-state permanent repository for the nuclear waste.

There's nothing of the sort anywhere, despite more than half a century of looking for such a place. After decades of searching, the federal government "finally" settled on Yucca Mountain in Nevada in 1987. Why Yucca Mountain? It's very dry there, far from population centers, and it was on Nevada Test Site land, which was already heavily polluted with radioactive debris from weapons testing.

But that didn't work out. And a nearby city -- Las Vegas -- grew from a population of around 600,000 in 1987 to nearly three million permanent residents today. Yucca Mountain is no longer "far from any large population centers" if it ever really was.

In July, 1999 the Department of Energy published an enormous document in four thick books called The Draft Environmental Impact Statement for a Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste at Yucca Mountain, Nye County Nevada.

I have a copy: It takes about half a foot of space on a bookshelf (see Figure 1).

The EIS lists the isotopic content of a typical Pressurized Water Reactor spent fuel assembly, such as exists at Diablo Canyon. (see Figure 2 (Table H-4), which also lists the isotopic content for Boiling Water Reactor spent fuel -- but note that the values shown are for "low burnup" fuel. Diablo Canyon has been using "high burnup" fuel for several decades).

The values in Table H-4 are enormous quantities of nuclear waste -- and that's just for one fuel assembly. A typical PWR will have two to three dozen fuel assemblies in each dry cask, and Diablo Canyon already has over 3 million pounds of spent nuclear fuel, much of it in nearly 100 dry casks -- over 2,000 fuel assemblies. Enormous amounts of additional fuel is also in the spent fuel pools and the operating reactors (approximately 2,000 additional fuel assemblies).

Of the 3+ million pounds of spent fuel at DCNPP, at least 50,000 pounds of it is plutonium -- an incredibly toxic, man-made element that is virtually non-existent in nature. Enough for approximately 10,000 nuclear weapons. Just one pound of plutonium, if divided evenly and somehow distributed into the lung of every person on earth, is enough to cause everyone on earth to be virtually certain to get lung cancer. A few millionths of a gram is a lethal dose of plutonium.

Plutonium is incredibly toxic, but it's hardly the only hazard that PG&E has created at DCNPP. Plutonium is considered an "activation product" because it was created when other elements absorbed neutrons, then decayed, creating new protons. Fission products (which result from splitting uranium and plutonium atoms) are also incredibly toxic and highly radioactive -- sometimes thousands of times more radioactive than plutonium, which in turn is thousands of times more radioactive than uranium. Many fission products, such as strontium and cesium, are "bone-seekers," others, such as radioactive iodine, are taken up by the thyroid. Tritium can end up anywhere in the human body, because it is a radioactive form of hydrogen. (Tritium is called Hydrogen-3 in Table H-4).

Fission products created within the uranium fuel pellets escape from the fuel pellets and lodge -- under very high pressure -- in the gap between the fuel pellet and the fuel cladding (a buildup of fission products is one reason the fuel has to be removed from the reactor after a few years and replaced with "fresh" reactor fuel).

The fuel cladding (usually an alloy of zirconium) is liable to catch fire if, for example, and aircraft were to crash into a dry cask (see photo (figure 3) for a comparison of the relative sizes of a large jet to a dry cask).

If the fuel cladding burns, the fission products will be released to the atmosphere. This is a very serious accident, but by no means the worst that can happen. That might come next:

If the fuel cladding burns away, the fuel pellets themselves will fall to the bottom of the spent fuel cask (see figure 4). As they pile up in a fire, they might just sit there. But whoa to the firefighters who might try to put the fire out with a stream of water! Water slows neutrons down very effectively -- it's used in PWRs and BWRs for that purpose, because "slow" neutrons (also known as "thermal" neutrons) are far more likely to be "captured" but other uranium and/or plutonium atoms, thus causing a self-sustaining nuclear reaction.

This is known as a "criticality event". Even very old fuel -- hundreds, perhaps even thousands of years old -- can "go critical" under the right conditions -- and a spent fuel cladding fire followed by water intrusion creates the right conditions for a criticality event, although there are other scenarios as well (and what if it's raining when the plane crashes, for instance)? This is all described in the 1999 EIS (see section K.2.5).

At Yucca Mountain, they had a plan to prevent such a scenario. It was two-fold: Firstly, they gambled that an airplane was unlikely to strike the spent fuel canisters (this was Nevada, after all, the gambling capital of America). Secondly, they intended to store the spent fuel canisters in buildings with very thick cement walls, so that even if a plane did strike the site, they concluded it was unlikely to cause a "significant" fuel release to the environment. And very unlikely to cause a criticality.

Their guesswork (they admit that many numbers were "rough estimates") undoubtedly minimized many potential dangers, but the most egregious was probably ignoring sabotage or terrorism in the form of an intentional airplane strike. Could that be excused since it was before 9-11? And before a GermanWings pilot intentionally flew a planeload of people into a mountain? And before MH-370 was flown off course until it ran out of fuel and dropped into the sea with all souls lost? And before a China Airways plane plummeted nearly straight down for no apparent reason a few months ago? And before Russia threatened to destroy the Zaporizhzhia nuclear reactor site in Ukraine, which they are continuing to threaten to do?

No, there's no excuse for ignoring intentional air crashes: In the 1970s, at least one hijacker had already threatened to crash the jet he had taken control of into nuclear facilities (fortunately, he did not follow through with that threat.)

Spent fuel at Diablo Canyon is NOT properly contained. It is NOT safe. It will NOT be going to a permanent repository any time soon -- if ever.

Can we really afford to double the amount of waste there, if we won't even properly contain what is already there, on earthquake faults, exposed to airplane strikes or other terrorism, from drone swarms to laser-guided rockets?

The longer spent fuel has been removed from a reactor, the safer it is. It's never safe, but it is several orders-of-magnitude more dangerous in the first few decades immediately after it is removed from the spent fuel pools (where it is so dangerous, if the pools drain for any reason, or circulation is stopped for too long, the worst ecological disaster in American history would occur).

We should not be making more nuclear waste, since there are clean alternatives that do not add to the risk with every kilowatt of electricity they produce.

Electricity is not, and never was, the main product of Diablo Canyon.

Nuclear waste is, was, and always will be what Diablo Canyon will be most famous for creating (see figure 5).

Do not relicense the reactors at Diablo Canyon. Enough is Enough!

Ace Hoffman
Carlsbad, CA

Figure 1:

Figure 2:

Figure 3:

Figure 4:

Figure 5:

Figure 5 is from:

Enough is Enough! (90-second video about Diablo Canyon):

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