Add a Conveyor Throughput Gate

The game currently has no practical way to control how many items are allowed to leave a storage over a certain period of time.
This is especially frustrating in the nuclear industry. Nuclear waste should ideally remain inside protected storage, but some of it is needed for fast-neutron processing. Once the storage is connected to a conveyor, much more waste than necessary can be pulled out and exposed on belts.
Slower conveyors, balancers, priorities, and storage limits do not really solve this problem. They can control the route or maximum belt speed, but they cannot limit the actual quantity released.
It would be very useful to have a small gate-like conveyor building that allows only a specified number of items to pass during each cycle. This would make nuclear waste handling much safer.

You should always have storage as close to processing as possible and try to process it ASAP, maybe even do not store spent fuels at all and only store plutonium instead.
Or you can just leave it to vehicles and do not use belts at all.