In space, you'd expect much the same effect from blast, radiation, and heat as in atmosphere.

Of course, with no atmosphere to "carry" the blast effect, it's going to be greatly limited.
There will be little or no effect from what you might call "shrapnel"... The bomb itself is going to be vaporized and you're not going to get chunks of stuff flying around at high velocity.
Both we and the Russians experimented with the effects of nuclear weapons in space, if you get a chance there's a documentary on Netflix about the development of the hydrogen bomb.
It covers these space-based tests.

Effects of nuclear explosions in space?
As of right now, I don't seem to be able to load my profile picture. Nor a bunch of others. Nor even some images in posts. My profile looks like this when I load it:


  


And here is the MSE users page:


  


Browser developer tools indicate I'm getting to the server, and it's sending back a 404, with the response body being the following XML:

&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;Error&gt;
    &lt;Code&gt;NoSuchBucket&lt;/Code&gt;
    &lt;Message&gt;The specified bucket does not exist&lt;/Message&gt;
    &lt;BucketName&gt;i.stack.imgur.com&lt;/BucketName&gt;
    &lt;RequestId&gt;5AF32B5D1A1F83FA&lt;/RequestId&gt;
    &lt;HostId&gt;XClSHkzldpcUQUk2v3zE5EmjQoxTqSntgy/AqVUZrJBw93+//ygbp1iQGmqY0cir&lt;/HostId&gt;
&lt;/Error&gt;


In fact, while typing this post in, the preview is showing the second of the above images, but not the first. Both uploaded identically via the Upload Image button.

For reference: Win 7, IE11, all patched, no plugins or userscripts

Edit: The problem seems to be intermittent somewhat, and to keep hopping around; images that failed to load a few minutes ago start working, while others start failing. Also, it's happening across multiple browsers. Sometimes, an image will fail, but then the same image will also succeed, but with different size parameters. But those same parameters that worked, don't work on another image.
