Getting back into physics after engineering masters

I'm a 2013 graduate with a BS in physics (no specialization). My current line of work doesn't allow me to pursue a degree in-residence however an advanced degree is required for career progression. I've been looking into nuclear engineering programs offered online, mainly Penn State. However, I would like to ultimately earn my Ph.D. in physics. My questions: how difficult would it be to (1) earn a Masters in nuclear engineering and (2) then get back into physics to earn my doctorate with only a nuclear engineering masters as a foundation?



I've read the other postings related to physics BS-to-nuke engineering but my concern is damaging my chances of pursuing the doctorate.



Thanks in advance for the input/advice. If you need any additional info please let me know.