PAINTSQUARE BLOG

“It is the mark of a truly intelligent person to be moved by statistics.” – George Bernard Shaw

Let’s start with the numbers:

• Weight: 40,000 tons – Roughly the weight of 3 Eiffel Towers, 107 fully loaded 747s or the USS Missouri battleship.
   
• Height: 590 feet tall – Roughly the height of the Seattle Space Needle or the Washington Monument.
   
• Length: 530 feet long – Roughly one and a half football fields.
   
• Design Life: 100 years – Roughly how long my wife thinks it will take for me to pay attention when she’s talking.
   
• Environment: Designed to withstand temps between -45 degrees Fahrenheit and 113 degrees Fahrenheit and winds up to a class 3 tornado, 206 mph, calculated at a once-in-a-million-year event, and a 5.4 magnitude earthquake, a one-in-ten-thousand-year event.
   
• Cost: $2.3 billion contributed from more than 40 nations.

By Tim Porter / CC BY-SA 4.0 via Wikimedia Commons

A structure called the New Safe Confinement (NSC) was recently moved into place at the Chernobyl nuclear power plant in an effort to contain the release of radioactivity. The previous shelter structure, built 30 years ago, risked failure from prolonged exposure to the environment and corrosion.

It’s called the New Safe Confinement (NSC). Picture a massive, movable hangar-like dome designed to cover the highly radioactive remains of the nuclear reactor at Chernobyl, Ukraine. 

Addressing Disaster

Going back to the numbers, Chernobyl remains the single worst man-made disaster in history.

On April 26, 1986, plant operators were conducting a test on an emergency water cooling system. At around 1:30 in the morning, pressure in the reactor built up and exploded, lifting and destroying the 1,000-ton concrete lid covering the reactor and spreading radioactive dust, well, everywhere.

The first ever photo taken of the Chernobyl disaster, 14 hours after the explosion. https://t.co/z8e4IjVtcp pic.twitter.com/zIx9yF4ffJ

— Old Pics Archive (@oldpicsarchive) December 20, 2016

Dozens of people died within the first few days, and, depending on who you read, it’s estimated that between 10,000 and 100,000 have died over the years from exposure and another 70,000 have been left with varying degrees of disabilities. It released greater than 100 times more radioactivity than the atomic bombs dropped on Nagasaki and Hiroshima combined.

Let’s just say April 26, 1986, was a very, very bad day for those working at, and living around, the facility.

The Soviet Union (as it was known back in the day) hastily built a concrete and steel containment structure called the Object Shelter to try to stem the continuous release of radioactivity. 

The shelter, however, continues to succumb to the environment and our collective nemesis—corrosion, and there is considerable concern that it might fail or collapse completely.

Hence, the development of the NSC.

Striving for Protection

So how does this fit in with a blog about corrosion fundamentals? 

Well, I’m a self-confirmed corrosion nerd, and when I first heard about the NSC being built around 2011, I was fascinated. How do you build something so big, designed to last for 100 years, and corrosion-protect it?

By Mond / CC BY-SA 3.0 or GFDL via Wikimedia Commons

After the April 1986 disaster, a concrete and steel containment structure called the Object Shelter, shown in the background of the memorial monument, was hastily built around reactor number 4 to try to stem the continuous release of radioactivity.

This is what I do every day for our clients. I try to figure out creative, technically sound, vendor-neutral systems and practices for corrosion mitigation.

Anyone trying to corrosion-protect anything gets pulled in various directions by vendors who firmly believe their systems and ideas are best.

If you talk to a paint company, they’ll tell you to paint it. Talk to a metallizing company, and thermal spray aluminum (TSA) is the way to go. Talk to a cathodic protection company, and that’s the ticket. And so on.

However, while coatings are the most prominent solution to most corrosion issues, they are never our first choice. Why? Because the second you install a coating system, you’ve created a maintenance issue. 

Now, we’ve designed coating systems with an estimated service life in excess of 100 years. However, at some point, virtually all painted or coated surfaces and assets will require maintenance.

Case in Point

Just yesterday I was consulting with a large oil company in Europe about a 1.2 million-gallon concrete wastewater tank. The tank was built about 15 years ago and had started to leak. This was anticipated, and the plan was to keep crack-injecting it (chasing the cracks) until it stopped leaking. Several years later, the tank is now watertight. 

This week’s #innochat topic was triggered by this about the radiation shield being built around the Chernobyl plant: https://t.co/Dtv4KeqMbq

— John W Lewis (@JohnWLewis) December 8, 2016

The company contacted our firm because it was going inside to inspect it for the first time, and was considering lining the interior. The firm wanted me to review the coating options presented to it by a variety of vendors and coating companies. 

The coating options were mediocre, and some were unsuitable, but my first question was: Why are you going to do anything to the interior?

The liquid stored inside the tank was not erosive to the concrete. There was no indication that rebar was being attacked. There was no evidence of any issues with the vapor-space. And the tank was no longer leaking.

While coatings are one of the tools in our toolbox, I saw no technical justification to do anything on the tank interior, unless there was a technical reason to do so once tank entry was made.

Otherwise, the company might just be creating more work for itself by addressing a problem that doesn’t exist.

Constructing the Dome

Along those lines, I was interested to see what solutions engineers would come up with for the NSC. And the technical solutions did not disappoint.

First, let’s understand how the dome works.

It was built in two sections roughly 200 yards away from the Object Shelter (due to the radiation at the site itself) and then slid roughly 330 yards into place. This was done twice, once for each half. 

By Tiia Monto / CC BY-SA 3.0 via Wikimedia Commons

The NSC was constructed in two sections about 200 yards away from the existing Object Shelter and then slid roughly 330 yards into place.

An added fascinating fact (for fellow nerdlings) is that the jacks used to raise and move the dome are the same ones that were used to raise the Kursk submarine from the bottom of the Barents Sea (354 feet below the waves) in 2001. For those who don’t recall, the Kursk was an ill-fated nuclear Russian sub that sank, killing the entire crew of 118.

The dome has a 13-yard annular space, as is often the case with large domed-structures. I’ve walked inside the annular spaces of both the Duomo in Italy’s Florence Cathedral and at the Vatican, St. Peter’s Basilica’s Dome. It’s a common means of making structures like this, and allows for interior maintenance.

Containing Radioactivity

However, the NSC is designed to contain a nuclear waste pile, which is still actively giving off radioactive contamination and will do so for decades.

The entire goal of the NSC is to contain radioactivity emanating mostly in the form of dust particles. 

From a corrosion perspective, there are three surfaces and environments that require consideration:

1. The primary containment surface, which, you would see if you were looking up at the dome from ground level;

2. The interior of the annular space (and associated supporting structures); and

3. The exterior shell, which is exposed to the elements.

1. Primary Containment Surface

The NSC’s primary containment surface is designed to resist corrosion for 100 years, and also to support the framework for two interior construction cranes, each able to lift and move more than 50 tons. 

To address these needs, the interior containment was made of 95,000 square yards of type 304 stainless steel, which is the most common form of stainless steel used worldwide. 

By Tim Porter / CC BY-SA 4.0 via Wikimedia Commons

The NSC was built with type 304 stainless steel; type 316L stainless steel; and painted carbon steel supports, beams and structures.

The 20-mil thick plates are tightly fitted to a galvanized deck with no ribbing or other modifications to the surface, to minimize the likelihood of radioactive dust clinging to the surface. The annealed stainless steel panels were sealed with tape and radioactive-resistant silicone to maintain an airtight space within the dome.

Sadly, I was not able to find application details, which would be interesting, as would the QC that went into the erection.

2. Interior of the Annular Space

The massive 33-foot annular space of the NSC is a complex web of carbon steel supports, beams and structures, all painted to reduce corrosion. However, the long-term solution to corrosion prevention is simple and brilliant.

The entire space will be maintained at a slight, positive pressure to ensure no radioactive particles migrate up and into the space (conversely, the containment area will maintain a slight negative pressure). And for corrosion protection, the lightly pressurized air will receive desiccant dehumidification to maintain the RH at below 40.

As we all know, for corrosion to take place, we need ACME:

Anode

Cathode

Metallic Pathway

Electrolyte

The first three (anode, cathode and metallic pathway) simply live within all steel surfaces. The only thing corrosion professionals can modify (other than with CP, metallic coatings, etc.) is removing the electrolyte. That’s all barrier coating systems do. 

However, with humidity maintained at below 40 RH, there is not sufficient humidity (electrolyte) for corrosion to take place, or, to take place at such a low rate as to be irrelevant.

Another example of where simply removing the humidity from an environment is sufficient to stop corrosion is sulfuric acid stored in carbon steel tanks.

We’ve consulted on, and lined, many sulfuric acid tanks, and our first question to our clients is if they are able to control the humidity and moisture inside the vessel. For example, 66 Baume sulfuric acid (roughly 93 percent) is not corrosive at all to carbon steel, if you can keep out moisture. The problems start if water or humidity gets into the mix. 

3. The Exterior Shell

The exterior shell of the NSC was made of 105,000 square yards of Type 316L stainless steel (same as my Apple watch!) with 2 percent molybdenum for enhanced corrosion resistance.

All in all, I thought the corrosion mitigation design was simple and technically sound. That being said, I am well out of my area of expertise when it comes to the effects of radioactivity on polymers, metallics and all of the other materials involved in the project. 

I’m anticipating some questions pertaining to chlorides. That is, stainless steel can be susceptible to corrosion if exposed to chlorides, and I could not find any documentation relating to the presence of chlorides within the affected, or surrounding, areas.

My concern would be that even if there are very, very small amounts of chlorides somewhere, there may be a long-term risk if they are able to build up and become concentrated over time.

Of course, the long-term success of this venture remains to be seen:

• How well will the air pressure systems and desiccant humidification be maintained?
• Are there any unanticipated consequences (a subject of a future blog) in building something so large and unique for such a unique environment?
• What will happen when the deteriorating Object Shelter continues to deteriorate and, ultimately, collapses?

As in all things, time will tell.

With Gratitude

As this is my last blog post of the year, I would like to take a moment to share my deepest gratitude to all of you who follow my blog. I consider it an honor to have this space to share my thoughts, and strive to make them informative, entertaining and thought-provoking. 

Wishing all of you, and those close to you, very happy holidays and a healthy, happy, rewarding and prosperous 2017.

ABOUT THE THE BLOGGER Warren Brand Warren Brand’s coatings career has ranged from entry-level field painting to the presidency of two successful companies. Over nearly three decades, he has project-managed thousands of coating installations and developed specs for thousands of paint and coating applications. NACE Level 3 and SSPC PCS certified, Brand, an MBA and martial-arts instructor, now heads Chicago Corrosion Group, a leading coatings consultancy. Contact Warren. SEE ALL CONTENT FROM THIS CONTRIBUTOR