Bottomless & wondering... referring to a old clay basement sump basin. Is this set up OK? Radon?

There's different ways to install sump pumps.

Some have a plastic pit with piping draining into it. Others have a slot cut around the floor that directs water into the pit. The pits can be steel, clay, plastic etc.

The house I grew up in had two pits with just gravel in the bottom and the pumps sat on bricks and in that situation they worked very well, so well that it needed 3 pumps to keep up at times. But in other situations where perhaps the ground doesn't perk very well it may not work at all. If the ground doesn't perk you need to get the water into the pits some other way.

In my own basement I installed two pits on opposite ends of the basement that have plastic bottoms and a ton of holes drilled in the sides, I then dumped a ton of small gravel all around the sides of the pits. This was just how I felt like doing it and I didn't have to dig as deep as I didn't need to line the bottom with gravel. The gravel is there to help stop dirt / mud from getting into the pit. It's basically a coarse filter.

I've also heard of basements being sealed well enough they have the pit sealed to keep ground water out of it and only allow water above a certain level in. I've personally never worked with this, so I don't really have an opinion but some claim it works great. My objective was always to pull the water table down well below the floor but that may not be practical, or even possible in some situations.

As far as Radon, modern setups have covers over the pit and they're often vented to the outdoors. That's a separate subject. I've heard of just venting the pit outside, I've also heard of piping them into a radon fan to pull a negative pressure on the pit. If you have concerns of radon there's nothing stopping you from adapting some kind of cover to the pit and venting it outside.

Torrington area, if I recall, @LS123 ?

Amaazing how well the old stuff works, isn't it?

Unless you have really sealed up your basement from draughts, I doubt that you have a radon problem — but Torrington Area Health can help you out further on that.

Radon daughters, now called Radon progeny are what Radon gas breaks down into and some of them are what's really dangerous.

As far as I know, no one tests for the progeny? They test for Radon gas no?

Here is a link to the test kits recommended by the US EPA. They offer both long and short term kits. https://sosradon.org/test-kits . Also check with your state and local health departments as they may offer these services for free.

Unless you're in a uranium mine, the dose level from ground leach radon is negligible. You'd catch more internal counts from eating some bananas (K40) or a bag of Brazil nuts (Ra 226).

The salt mine where I spent two decades of my life had dangerous levels of Radon in the exhaust air.

Doesn't surprise me a bit. Everyone seems to be terrified of Radon, and it's an easy upsell with a huge profit margin.

The levels they want are the same as outside now from I've heard.

I have no idea what is and isn't safe, I'll admit that but for my own home I've decided to ignore what others are doing in my area for now.

No amount of Radon exposure is safe.

My sister in law was required to install a radon mitigation system/ventilation system to deal with solve the radon problem that they found before she could sell the home as the home was built on a shelf foundation of limestone bedrock. The local bank that I did business with for 54 years found that the branch location had a radon exposure problem and they had to install a huge air exchange system to mitigate the radon exposure condition.

I think the mitigation installers want to

That's just not true. It's based on what's called the "linear no threshold model" which has no statistical basis.

Worth the 10 bucks if you really want to get into the weeds on low dose exposures.

https://www.amazon.com/Radiation-Exposure-treatment-modern-handbook-ebook/dp/B00D7KLQYY

Don't get me going on the statistical problems — or scientific problems — with the linear no threshold model approach. Just don't.

You honestly need to know more about this issue PLEASE.

The part I find curious is @leonz is big into burning coal.