Plutonium is much rarer in nature than uranium and is more commonly used for bombs rather than as reactor fuel. Like uranium, it comes in various isotope forms, with plutonium 239 the most commonly used. It is mixed with the much more unstable plutonium 240 to generate power.
It's my understanding that a horse's knees close around age 2- 2 1/2. My gelding JUST turned 3. A couple days ago in fact. Will a horse's knees almost certainly be closed by that age?
Horses commonly live to be 25 - 35 years old, and horse ages translate into human ages almost linearly, but with major differences in age equivalents as babies where mature at a rate far faster than humans, reaching pony puberty by age two: