Chapter 1: Good News for Steel Production

We have some fantastic news! Our steel is now devoid of radioactivity, thanks to significant environmental improvements. This means we no longer need to salvage old warships for their steel.

In the past, the armor plating from sunken battleships was worth a fortune—literally, worth its weight in gold! But if you were to recover it today, you'd find it's worth much less—and that’s a positive development.

During the latter half of the twentieth century, human activities inadvertently polluted our atmosphere, leading to the radioactivity of steel. This wasn’t intentional, but it created numerous challenges. Fortunately, in recent years, we have made strides in reducing pollution to the point where we can produce non-radioactive steel once again!

For many, this might come as a surprise. “Wait, my toaster is radioactive?” Yes, it is! Most metal items in homes built before recent years contain some level of radioactivity. So, what exactly happened? How did steel become radioactive, why is this a concern, and do we need to replace all the steel in our homes? Let’s explore!

Section 1.1: Understanding Radioactivity in Steel

When we think about radioactivity, we often picture heavy elements like uranium or plutonium, which naturally emit radiation. But since the 1940s, we’ve also had radioactive air.

Between the 1940s and 1960s, nuclear powers conducted numerous airborne nuclear tests, dispersing radioactive particles not only at the test sites but also throughout the atmosphere. This led to a significant increase in global background radiation, adding approximately 0.15 mSv (milli-Sieverts, a radiation measurement) annually.

(For context, eating a banana exposes you to about 0.0001 mSv, while a mammogram can yield about 0.42 mSv. The average home typically accumulates around 2.28 mSv yearly due to radon. Thus, while 0.15 mSv isn’t excessively high, it’s measurable.)

These airborne radionuclides include elements like cobalt-60, americium-241, cesium-137, and iodine-131, which get mixed into the air we breathe.

Subsection 1.1.1: The Steel-Making Process

Steel production involves smelting raw pig iron with oxygen to remove impurities. Iron contains various elements, such as silicon and manganese, which are converted into oxides during this process. However, when this process utilizes air from the atmosphere, it inadvertently incorporates radioactive particles into the steel.

The result? Steel that is slightly radioactive.

Chapter 2: The Solution to Radioactive Steel

So, what’s the remedy? The simplest solution is to utilize steel manufactured before the nuclear tests began. Notably, armor plates from decommissioned warships represent a significant source of pre-nuclear steel. Consequently, numerous salvage operations in the late 1900s sought to recover this steel for constructing detectors.

But is this still a concern today?

Absolutely not! We no longer have to worry about our steel being infused with radioactive elements during production. Since the Partial Test Ban Treaty of 1963, which halted nuclear detonations in the air, the levels of atmospheric radionuclides have notably declined.

By the 2010s, radiation levels from human-made sources had dropped to a mere 0.005 mSv annually above natural levels. Additionally, advancements in Geiger counter technology have improved our ability to filter out background radiation effectively.

Ultimately, this means that new steel can be utilized even in sensitive applications. Although older steel contains some trace amounts of radioactive elements, when it's reforged, these elements are eliminated, resulting in radiation-free steel.

In conclusion, while our steel was once radioactive, we are now in a much better position. We produce steel by injecting air into molten iron to purge impurities. The air was contaminated with trace radioactive materials from the 1940s onward, which became part of the steel. Thankfully, with the cessation of airborne nuclear tests, we can produce newly forged steel without the worry of radioactivity.

Let’s hope this trend continues and that we avoid any global incidents that could reintroduce radioactive materials into our atmosphere!

The first video titled "Why Steel from Before 1945 is Weirdly Expensive" explains the historical context and value of pre-1945 steel.

The second video, "Nuclear: Pre-Atomic Steel," delves into the implications of nuclear contamination in steel production.