Are Xenon 137 or Krypton 90 released by reactors?

Anti-nuclear activist Dr Helen Caldicott of the Nuclear Policy Research Institute has said in a major Australian newspaper that Xenon 137 or Krypton 90 are released by nuclear reactors. These particular isotopes break down into Cesium 137 and Strontium 90 respectively.

However, when I did a bit of research, I found that these isotopes are synthetic (as opposed to natural) so I was highly suspicious of her statement.

Can anyone tell me if these particular isotopes are actually released by nuclear reactors as part of their regular venting of various nobel gasses?

Although the radiochemical decay chain assumptions are correct the answer is:
No, they are not emitted as gaseous radioactive outlets, as the half-life of Kr-90 is around 3 seconds and Xe-137 has some less then 3,8 minutes. The time needed to diffuse out of the oxide matrix (ignoring cladding supposing micorcracks) out of the primary circuit to the filtering systems to the freezing systems (if present) out to the environment through the venting chimney is simply too long. And even if some individual atoms got out, their activity would be unmeasurable.
The only important gaseous emmision that cannot be stopped by filtering and freezing is Kr-85 with 10 years half-life. Its decay product is stable Rb-85.

Paul Henry wrote:

Anti-nuclear activist Dr Helen Caldicott of the Nuclear Policy Research Institute has said in a major Australian newspaper that Xenon 137 or Krypton 90 are released by nuclear reactors. These particular isotopes break down into Cesium 137 and Strontium 90 respectively.
However, when I did a bit of research, I found that these isotopes are synthetic (as opposed to natural) so I was highly suspicious of her statement.
Can anyone tell me if these particular isotopes are actually released by nuclear reactors as part of their regular venting of various nobel gasses?