1 / 15

Poisoning

Poisoning. Poisoning. Poisoning. Not anticipated! Reactor shut down!. Time scale: Hours and days. 135 Xe 10 6 b. 149 Sm 10 5 b. Poisoning. HW 28. Negative reactivity due to poison buildup. It is proportional to the amount of poison. Poisoning. small. Initial conditions?

suchi
Download Presentation

Poisoning

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Poisoning Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  2. Poisoning Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  3. Poisoning • Not anticipated! Reactor shut down! Time scale: Hours and days. 135Xe 106 b 149Sm 105 b Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  4. Poisoning HW 28 Negative reactivity due to poison buildup. It is proportional to the amount of poison. Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  5. Poisoning small • Initial conditions? • Clean Core Startup. • Shutdown (later). Assume no spacial dependence. Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  6. Poisoning HW 29 Show that: and Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  7. Poisoning • Now, we know Xe(t) Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  8. Poisoning • Shutdown. After the reactor has been operating for a “long” time. Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  9. Poisoning HW 30 Show that > 0 ? Height of the peak depends on I() and Xe(), i.e. depends on . Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  10. Poisoning Shutdown  Xe   negative  move control rods out  try to add positive reactivity  need to have enough reserve  costly to do that. If, the available excess reactivity can compensate for less than 30 minutes of poison buildup, can’t startup again after ~30 minutes of shutdown, because you can’t achieve criticality. Need to wait some 40 hours (in this case) for Xe to decay down. Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  11. Poisoning Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  12. Poisoning • Strategies • If you plan to shut down for “short maintenance”, think about stepback. • Examine different scenarios using this code from • http://www.nuceng.ca/ • Prepare your own report, code, calculations, graphs, comments, conclusions etc….. • Be creative and use whatever experience you gained during your study in this program. 20% (10 marks) of the final exam. Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  13. Poisoning • Xe Oscillations • (r,t) (spacial dependence)  flux  locally Xe burnup    (reactivity)   flux further   control rods globally in  flux  elsewhere Xe burnup   ….. Xe oscillation but limited by opposite effect due to increase (decrease) of I in the high (low) flux region. • In large reactors (compared to neutron diffusion length) local flux, power and temperature could reach unacceptable values for certain materials  safety issues. • Think of one sensor and one control rod  feel average flux  apparently OK  more sensors and control rods to locate and deal with local changes. Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  14. Poisoning • Permanent Poisons • 149Sm has sizeable but lower cross section than 135Xe. • It does not decay. • Start from fresh fuel: • Thus: Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

  15. Your Thesis Proposal !! Nuclear Reactors, BAU, 1st Semester, 2007-2008 (Saed Dababneh).

More Related