I need to be able to see over a much longer period to be able to speculate. On current conflict and prior for months.

I think they have that info, may be behind paywall.

My assumption is that natural variations are caused by changes in space weather, so nearby towns will show same change at the same time if change is natural. They does not. Also, daily variations are daily, so they don't last longer than day. Also, it is much more probable that you will see sharp rise from average with following staying at that level in case of accident. And if you suggest that there was previous accidents and they are regular, then background level in that area before the accident will not be equal to towns nearby. Backround easily could rise sharply due to accident, but it can't fall in the same manner, it is a long process. And background level jumps from previous consequent accidents will accumulate, so you have no chance to see exactly same level in that are as in nearby towns.

So, week of data with sharp rise in the middle is more than enough to make some conclusions if sensor is function normally and data is not manipulated.

Incased shells don't give that reading. Not into the atmosphere.

Easy test for you for ~$1. Buy a 2% thoriated tungsten welding electrode or ask for a short remainder of such if you have a welder among friends. Thorium undergo alpha-decay, but it decays into other elements that have noticeable gamma emissions. So it will have very low gamma radiation, adding something like 0.05-0.1 uSv/h to your background in close proximity. Then put it in steel box. Wait a year. You will find that box will become slightly radioactive too, may be 0.02uSv/h over background. Longer exposure will give higher radioactivity of casing. You know, all that high energy alpha, beta and gamma do nasty things with innocent elements sometimes making radioactive isotopes from them.

As for "into atmosphere" big amount of slighlty radioactive material will emit much more gamma-quants around, so you will register them on relatively large distances. If you have a coal powerplant around - ride to it with geiger counter. Coal ash is slightly radioactive, and working coal powerplant have higher radiation level than working nuclear power plant due to heaps of coal ash nearby. You will register higher radiation levels few miles from ash storages of power plant. And it is not in atmosphere, because in that case you will have higher background at much longer distances. It is heaps of ash have a lot of decays and some of their gamma-quants have a higher chance to reach your detector.

You're speculating it was munitions.

I clearly stated that it is my speculation. What's the problem? Any speculation is good enough if it fits observations. Your speculation about some new manufacturing process that started in Khmelnitsky exactly day before explosion that needs radioactive materials in so big amounts that they are detectable from a distance (?) is not different at all and rises much more questions.

But how abnormal is it?

Sudden rising of background after few days of low background and staying at rised level for few days is abnormal. Usually it is a clear pattern of some accident with radioactive material.

Again, I told you that I'm not exclude sensor malfunction or local contamination, next few days will show if that is a case. If it was an accident that level will stay for a long time. If it was a malfunction or local contamination you will see abnormal sharp drop in background level.

Or that information is just manipulated for whatever reason.

IDK. If you will measure body temperature for a week and suddenly in the middle it will rise from 36.6°C to 38.2°C - will you need a full history of body temperature for years before or it will be enough for you to make some assumptions without full-scale statistics research?

The shape of curve change is suspicious, not amount of change or its absolute value.

I need to be able to see over a much longer period to be able to speculate. On current conflict and prior for months.

I think they have that info, may be behind paywall.

My assumption is that natural variations are caused by changes in space weather, so nearby towns will show same change at the same time if change is natural. They does not. Also, daily variations are daily, so they don't last longer than day. Also, it is much more probable that you will see sharp rise from average with following staying at that level in case of accident. And if you suggest that there was previous accidents and they are regular, then background level in that area before the accident will not be equal to towns nearby. Backround easily could rise sharply due to accident, but it can't fall in the same manner, it is a long process. And background level jumps from previous consequent accidents will accumulate, so you have no chance to see exactly same level in that are as in nearby towns.

So, week of data with sharp rise in the middle is more than enough to make some conclusions if sensor is function normally and data is not manipulated.

Incased shells don't give that reading. Not into the atmosphere.

Easy test for you for ~$1. Buy a 2% thoriated tungsten welding electrode or ask for a short remainder of such if you have a welder among friends. Thorium undergo alpha-decay, but it decays into other elements that have noticeable gamma emissions. So it will have very low gamma radiation, adding something like 0.05-0.1 uSv/h to your background in close proximity. Then put it in steel box. Wait a year. You will find that box will become slightly radioactive too, may be 0.02uSv/h over background. Longer exposure will give higher radioactivity of casing. You know, all that high energy alpha, beta and gamma do nasty things with innocent elements sometimes making radioactive isotopes from them.

As for "into atmosphere" big amount of slighlty radioactive material will emit much more gamma-quants around, so you will register them on relatively large distances. If you have a coal powerplant around - ride to it with geiger counter. Coal ash is slightly radioactive, and working coal powerplant have higher radiation level than working nuclear power plant due to heaps of coal ash nearby. You will register higher radiation levels few miles from ash storages of power plant. And it is not in atmosphere, because in that case you will have higher background at much longer distances. It is heaps of ash have a lot of decays and some of their gamma-quants have a higher chance to reach your detector.

You're speculating it was munitions.

I clearly stated that it is my speculation. What's the problem? Any speculation is good enough if it fits observations. Your speculation about some new manufacturing process that started in Khmelnitsky exactly day before explosion that needs radioactive materials in so big amounts that they are detectable from a distance (?) is not different at all and rises much more questions.

But how abnormal is it?

Sudden rising of background after few days of low background and staying at rised level for few days is abnormal. Usually it is a clear pattern of some accident with radioactive material.

Again, I told you that I'm not exclude sensor malfunction or local contamination, next few days will show if that is a case. If it was an accident that level will stay for a long time. If it was a malfunction or local contamination you will see abnormal sharp drop in background level.

Or that information is just manipulated for whatever reason.

IDK. If you will measure body temperature for a week and suddenly in the middle it will rise from 36.6°C to 38.2°C - will you need a full history of body temperature for years before or it will be enough for you to make some assumptions without full-scale statistics research?

The curve of change is suspicious, not amount of change or its absolute value.