Radiation is an extremely common issue in a space environment. Without the protection of the ozone layer (as on earth) any and all forms of solar radiation are pretty much full blast into your sensitive little ocular and tactile sensors. Compounded by the fact that half or more of your security forces are walking around with personal radiation beam generators (any energy weapon) and you get the idea. Radiation: A problem.
What is Radiation
"In physics, radiation is a process in which energetic particles or energetic waves travel through a vacuum, or through matter-containing media that are not required for their propagation."
Radiation is basically light. Or to be exact, it's photons excited to some frequency and coming in waves or focused waves. What 'counts' as a form of light radiation? Radio, infrared, heat, visible light, microwaves, x-rays, gamma radiation... and so on. So. It is very common.
How does it hurt you?
"Radiation can be classified as either ionizing or non-ionizing according to whether it ionizes or does not ionize ordinary chemical matter."
"Radiation with sufficiently high energy can ionize atoms; that is to say it can knock electrons off of atoms and create ions. "
Ionizing radiation examples include x-rays and gamma rays. Non-ionizing such as heat or visible light. Which isn't to say that you can't be hurt by non-ionizing radiation - too much heat hurts anyone, but there are less DNA issues. Ionizing radiation does it's damage in addition to the initial energy absorption, in the form of ionizing DNA. It gives you cell death and cancer. (Ultraviolet radiation, as protected against by sunscreen - is partially ionizing. Wear your sunscreen boys and girls.)
Which is to say - the energy weapons your characters are running around with in game - are terrifying things and you should treat them as such. Stun settings are more like microwave pain guns. Lethal settings, you're *boiling* someone alive or searing parts of their body. The damage done is nothing like a projectile weapon and anything but clean.
What are the side-effects?
For your sake and others - don't muck with the containment field on an energy weapon! Radiation doesn't *care* what direction it's pointed - and without the field it's pointed at everything. Including you. And high radiation - such as found in energy weapons - cares even less about cover. As in: There is none. Some heavier metals will block it at lower levels - such as found when you get zapped with an x-ray and they put the heavy metallic vest over your innards cause they don't want to risk giving any *other* part of you cancer. (Hint: Don't get x-rays unless you absolutely must.)
High radiation will damage anything around it on a molecular level. This is why microwaves spark on metal - the metal is being ionized and pieces of it are discharging energy. That includes electronics. Put your iPod in a microwave and see how likely you still have a playable music list. Assuming that heat hasn't destroyed anything - the radiation will have destroyed the data. EMP and radiation does to electronic storage what a lit match does to paper on an atomic level. There's no getting that back - the physical ordering of the magnetic storage has been destroyed.
Radiation in space
Did you know one of the major medical oddities for early astronauts was why everyone once in awhile they would report seeing a sudden white flash of light? Even in a chamber without windows - just poof - flash of light in the corner of the eye - then gone. What was happening? Stray cosmic radiation ( http://en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena ). "Apollo astronauts reported seeing this phenomenon once every 2.9 minutes on average." Which is to say - cosmic radiation was triggering a visual response - which should also tell you how often astronauts were getting hit by radiation.
Common natural sources of radiation: Solar of course, that's what it is - a giant ball of it and most of it not in the visual range. Gas Giants - same thing. Natural material sources (uranium ores, etc) in asteroids.
We take for granted how much the ozone layer of earth protects us. Most rocky planets don't have an atmosphere or don't have an ozone layer - making radiation a day-to-day threat. Gravity wells provide some additional protect making even an ozone-less planet better for the radiation dose than a small ship floating near a sun.