# Nuclear fission and radioactive decay **URL:** \ **Category:** Factual Questions\ **Created:** [March 22, 2011, 1:31pm UTC](https://boards.straightdope.com/t/nuclear-fission-and-radioactive-decay/575601 "2011-03-22T13:31:21Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [March 22, 2011, 1:31pm UTC](https://boards.straightdope.com/t/nuclear-fission-and-radioactive-decay/575601/1 "2011-03-22T13:31:21Z")
I was listening to the news this morning, and they were talking about how it was a (relatively) good thing that most of the discharge from the Japanese nuclear plant was from one of the reactors. They knew this, because most of the release from the plant was Iodine-131, which has a half life of only 8 days. That means nearly all of the I[sup]131[/sup] would have decayed out of the environment in a matter of months. If the release had come from the storage pools, it would have consisted of Cesium-134, which has a half-life of about two and a half years. That would stick around for much longer. Yay… I guess. Now my question. What does U[sup]235[/sup], the primary fuel of a nuclear, reactor fissure into? I[sup]131[/sup] + Ce[sup]134[/sup] + 1 neutron = U[sup]236[/sup] Obviously, I’m missing something. What am I missing? Follow up: What does I[sup]131[/sup] decay into? ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [March 22, 2011, 1:37pm UTC](https://boards.straightdope.com/t/nuclear-fission-and-radioactive-decay/575601/2 "2011-03-22T13:37:52Z")
Different fission events can result in different elements as [fragments](http://en.wikipedia.org/wiki/Fission_product_yield). I-131 beta decays to Xe-131 ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [March 22, 2011, 1:58pm UTC](https://boards.straightdope.com/t/nuclear-fission-and-radioactive-decay/575601/3 "2011-03-22T13:58:39Z")
Stupid follow up question. Does Beta decay mean a Neutron changes into a Proton and releases an Electron and photon (gamma ray frequency, I’d wager)? What sort of decay releases a Beta Particle (2Protons/2neutrons, unless I’ve been wrong about that, too.)? ---
**Author:** ![yoyodyne](https://avatars.discourse-cdn.com/v4/letter/y/a9a28c/32.png) [@yoyodyne](https://boards.straightdope.com/u/yoyodyne)\ **Post date:** [March 22, 2011, 2:13pm UTC](https://boards.straightdope.com/t/nuclear-fission-and-radioactive-decay/575601/4 "2011-03-22T14:13:43Z")
Neutron goes to proton, electron, and anti-neutrino (for beta- decay). The released electron _is_ the beta particle, hence the name 😉 ---
**Author:** ![Steve\_MB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/steve_mb/32/5339_2.png) [@Steve\_MB](https://boards.straightdope.com/u/Steve_MB)\ **Post date:** [March 22, 2011, 2:40pm UTC](https://boards.straightdope.com/t/nuclear-fission-and-radioactive-decay/575601/5 "2011-03-22T14:40:20Z")
> [@Mollie\_Magill](#): > > Stupid follow up question. Does Beta decay mean a Neutron changes into a Proton and releases an Electron and photon (gamma ray frequency, I’d wager)? > > What sort of decay releases a Beta Particle (2Protons/2neutrons, unless I’ve been wrong about that, too.)? 2 protons and 2 neutrons is an _alpha_ particle. Some heavy elements (uranium, thorium, etc) emit them as part of the decay process. A beta particle is an emitted electron created when a neutron is converted to a proton – free neutrons do this spontaneously with a half-life of about 15 minutes; neutrons in some nuclei do it at various speeds depending on just how unstable the nucleus is. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [March 22, 2011, 3:57pm UTC](https://boards.straightdope.com/t/nuclear-fission-and-radioactive-decay/575601/6 "2011-03-22T15:57:24Z")
Thank-you. It’s been twenty(cough-cough) years since my last physics class.