How is Xenon-135 produced in a reactor?

How is Xenon-135 produced in a reactor?

• A. Radioactive decay from I-135 and radiative capture
• B. Direct fission of Xenon-135
• C. Activation by fast neutrons in the moderator
• D. Spontaneous fission of Xenon isotopes

Answer: (A)

Xenon-135 is produced in a reactor mainly through two paths in the ongoing neutron-rich environment. First, fission of fuel creates iodine-135 as a fission product; iodine-135 is unstable and beta decays with a half-life of about 6.6 hours to xenon-135. So a significant amount of Xe-135 appears as iodine-135 decays. Second, xenon-134 present in the reactor can capture a neutron (neutron capture with gamma emission) to become xenon-135 directly. Both pathways—decay of iodine-135 and neutron capture on xenon-134—build up xenon-135 in the core. The other options don’t describe how Xe-135 is formed: xenon isn’t produced by direct fission of xenon, activation of xenon by fast neutrons isn’t the primary production route for Xe-135, and spontaneous fission of xenon isotopes is negligible.

Xenon-135 is produced in a reactor mainly through two paths in the ongoing neutron-rich environment. First, fission of fuel creates iodine-135 as a fission product; iodine-135 is unstable and beta decays with a half-life of about 6.6 hours to xenon-135. So a significant amount of Xe-135 appears as iodine-135 decays. Second, xenon-134 present in the reactor can capture a neutron (neutron capture with gamma emission) to become xenon-135 directly. Both pathways—decay of iodine-135 and neutron capture on xenon-134—build up xenon-135 in the core. The other options don’t describe how Xe-135 is formed: xenon isn’t produced by direct fission of xenon, activation of xenon by fast neutrons isn’t the primary production route for Xe-135, and spontaneous fission of xenon isotopes is negligible.