You're worried about a nuclear development in Iran? You might want to look a little closer to home:

[Are_grits_groceries]

Commerce Township, Michigan

The radioactive boy scout:
When a teenager attempts to build a breeder reactor

<snip>
What the men in the funny suits found was that the potting shed was dangerously irradiated and that the area’s 40,000 residents could be at risk. Publicly, the men in white promised the residents of Golf Manor that they had nothing to fear, and to this day neither Pease nor any of the dozen or so people I interviewed knows the real reason that the Environmental Protection Agency briefly invaded their neighborhood. When asked, most mumble something about a chemical spill. The truth is far more bizarre: the Golf Manor Superfund cleanup was provoked by the boy next door, David Hahn, who attempted to build a nuclear breeder reactor in his mother’s potting shed as part of a Boy Scout merit-badge project.
<snip>
I met with David in the hope of making sense not only of his experiments but of him. The archetypal American suburban boy learns how to hit a fadeaway jump shot, change a car’s oil, perform some minor carpentry feats. If he’s a Boy Scout he masters the art of starting a fire by rubbing two sticks together, and if he’s a typical adolescent pyro, he transforms tennis-ball cans into cannons. David Hahn taught himself to build a neutron gun. He figured out a way to dupe officials at the Nuclear Regulatory Commission into providing him with crucial information he needed in his attempt to build a breeder reactor, and then he obtained and purified radioactive elements such as radium and thorium.
<snip>
Now seventeen, David hit on the idea of building a model breeder reactor. He knew that without a critical pile of at least thirty pounds of enriched uranium he had no chance of initiating a sustained chain reaction, but he was determined to get as far as he could by trying to get his various radioisotopes to interact with one another. That way, he now says, “no matter what happened there would be something changing into something–some kind of action going on there.” His blueprint was a schematic of a checkerboard breeder reactor he’d seen in one of his father’s college textbooks. Ignoring any thought of safety, David took the highly radioactive radium and americium out of their respective lead casings and, after another round of filing and pulverizing, mixed those isotopes with beryllium and aluminum shavings, all of which he wrapped in aluminum foil. What were once the neutron sources for his guns became a makeshift “core” for his reactor. He surrounded this radioactive ball with a “blanket” composed of tiny foil-wrapped cubes of thorium ash and uranium powder, which were stacked in an alternating pattern with carbon cubes and tenuously held together with duct tape.

Even though he had been exposed to what experts estimate to be many times the normal amount of radiation human beings are exposed to in a lifetime, in just a few weeks or months, David Hahn tried to build another reactor in 2007. Here’s a photo of Hahn taken by police at the time. It’s believed the scars and rash on his face are the result of exposure to radiation.

http://www.harpers.org/archive/1998/11/0059750

This is a long, fascinating and scary story. They had to do a Superfund cleanup. Because of the radioactive dust he released, 40,000 residents or more were put at risk. He didn't achieve critical mass, but he was still working on it.

Google and you will find other teenagers who have achieved different results working on nuclear problems.
TEEN GOES NUCLEAR: He creates fusion in his Oakland Township home
http://research.lifeboat.com/teen.goes.nuclear.htm

So with the info about how to build a nuclear device on the internet and idle hands, the problem you think is somewhere else may be too close for comfort. Do I think DHS can locate all these merit badge contenders? Nope.
They have already proven they can make dangerous devices.

[stray cat]

1. How much plutonium did the kid have relative to Iran?

and I assume they didn't pat him on the head and say well done continue the good work....

[Are_grits_groceries]

2. He wasn't aiming in that direction.

However, he managed to accomplish a lot more than one would think somebody could. I know he wouldn't be able to compete with Iran on scale. However, he could make a hell of a mess.

If he had so chosen, he could have made a "dirty bomb" with some ability to endanger people. That would be more worrisome than a reactor or a nuclear device.