High radiation and mineral richness set the barren R class planets apart. Life is not possible without protective measures that require enormous amounts of energy to maintain. No food or water can be found there and needs to be imported. Those who do not fear hair loss, impotency and early radiation death and want to get rich quickly, should settle here - the ore and metal production is higher on these planets than anywhere else.
Worker increase per cycle (3 hours) is a random value between 1.2% and 2.4% plus above-mentioned bonuses when upkeep is met.
If upkeep is not met workers leave.
When population is over 100,000, an overcrowding-effect takes place and growth will slow down with increasing population. For very big planets and starbases there may happen a worker-decrease, even if all upkeep is provided.