According to this NN.com article, http://www.naturalnews.com/044369_chlorella_heavy_metals_mercury.html
Chlorella does not bind with cesium-137. In case you were wondering, chlorella has very little ability to bind with radioactive cesium isotopes such as cesium-134 or cesium-137.
As you probably know if you are a regular Natural News reader, I've already tested over 1,000 candidate substances for cesium binding potential, and I've found a formula that captures radioactive cesium isotopes very effectively. Nearly all substances fail this test, as cesium is a particularly difficult element to capture. Chlorella's binding potential with cesium isotopes is also very poor, ranging from 0% to a high of just under 15%, but with the bulk of the results coming in under 4%.
Again, these numbers are not scientifically significant, so we must conclude chlorella has no special ability to bind with cesium isotopes.