The problem is that to this day we struggle to fully understand the effects of long-term low-level radiation exposure because figuring those out usually requires long-term epidemiological studies, which are expensive and complex [0]
As the study itself states: "These conclusions are regrettable because low statistical significance only means that chance has not been excluded as an explanation, assuming no bias and no real effect. In more detail, p values -that is, the probabilities that observed effects may be due to chance - are affected by both the magnitude of the effect and the size of the study. This means the results of statistical tests must be interpreted with caution [26]."
Meta studies based on statistical analysis is inherently challenged. This one is no better (and no worse) than the others.
"Whatever the final explanation for the increases, the KiKK study and its implications raise many questions, including whether vulnerable people, such as pregnant women and women of child-bearing age, should be advised on possible risks of living near nuclear power stations."
and:
"It is recommended that US regulatory agencies should establish a KiKK-style epidemiological study of cancer incidences near all US nuclear power stations with precise distances being measured between cancer cases and nuclear reactors."
The point here is that our understanding of these impacts is obviously not as complete as many people like to pretend.
If nuclear plants caused childhood cancers, then they ALL would cause childhood cancers, so a scientific study would say "This mechanism, when present, has this effect. Here is our experiment to prove that, here are the results of the proof. We predict that if you look anywhere else where this mechanism is present you will see the same results."
If low level radiation did cause childhood leukemia then there would be clusters in Arvada Colorado and Moab Utah. But there aren't. So why not? When the science is done, and the other variables eliminated, to date there is no study that links low level ionizing radiation to any harmful effect on humans. Even using that term is difficult because there is alpha, beta, and gamma radiation based on electrons, protons, and neutrons. Only Gamma radiation has any sort of penetrating capability at all.
So without the science, this study means nothing. Now if they can follow up with core samples, air samples, water samples, and food products to see if there are any nuclear fission byproducts getting into the area around the plant that would be good science.
[2] https://www.acsh.org/news/2018/06/29/problem-p-values-13130
