Teachin g N o tes

Operation a l Reacto r Saf et y Course

Lecture : 1 – Introductio n an d Overview

Objectiv e:

To provide a course overview by reviewing the course le ctures and course objective which is to develop a fundam e ntal understandin g of the technical a nd operational aspects of reactor safety.

The second part of the lectur e is to give students a broad overview of nuclear reactors (PW R s, BWRs and HTGRs) to be followed by a review of basis nuclear reactor physics. The broad overview of reacto r s is to give stude n t s the big picture of what a reactor is and how it works to be followed by more detail in term s of the f undam e ntals which will follow in subsequent lectures.

Ke y Point s t o Brin g Out:

Slid e num ber Point s

2-6 To be sure students appreciate what the course is about as well as Expectations and grading of the course

6-9 Explanation of the com pl e te fuel cy cle to appreciate the source of Uranium , m i ning, m illin g, conversio n, enrichm ent, fabricatio n and back end. Fuel m a de in pellets source of fission energy

10-19 Review how electricity is m a de – ne ed for heat rem oval – basics of Power conversion, Operating reactor types to show that there are m a ny, the fi ssion process, energy released per fission, creating the core from the uranium – focus on pins, assem b lies and configuration in th e reactor vess el

20 Take som e tim e on this slide to explain the key elem ents of core Design and how that affects how m u ch power you can produce, m a terial limitations and how core design in term s of core power distributions is im portant to al low for m a xim u m power generation. Core heat removal is im portant to prevent fuel failure as a r e the safety system s to prevent core d a mage if key sy stem s are lo st.

Lastly d i scu ss the need f o r the con t ainm ent or co nfinem ent of radioactivity should fuel failures or dam a ge occur. Do not forget the purpose – nam e ly electricity production.

21-23 These slides are intended to show th e entire plant configuration in Term s of how it is really orga nized – go over locations of key equipm ent on slide #21 and then m a ke the point on the schem a tic that it is a complex system of m a ny s upport system s which require monitoring and control which leads to slid e of th e ABW R control room . Summ arize by reinforcing notion that the objective is to m a ke electricity safely.

26-29 Explanation of boiling water reacto rs – key points – like a fossil Boiler – bo iling in reacto r vessel, steam separato rs , dryers, d i rect cycle to turb ine gene rato r. Poin t ou t need f o r re circulation pumps for core cooling, different type of fuel bundles due to boiling in core – channels needed to assure adequate core cooling, control rods in between fuel elem ents – run rodded which need to be moved m onthly to m a intain even burnup – fuel has burnable neutron absorbers, to deal with depletion.

30-35 Pressurized water reacto r s – expl ain differences in term s of Operating pressures, no boiling – inclusion of steam generator, pressurizer, m a in coolant pum ps, use of boron for depletion, containm ent structure, core configuration.

36-39 Gas cooled reacto r s – prism a tic and pebble, history – Peach Bottom , Ft. St. Vrain, helium cool ant, explain power conversion cycle – d i rect cycle Brayton – single phase helium coolant – NGNP, fuel type difference – ceram i c coated particles, prism a tic – requires refueling – pebble online ref ueling.

40 Review key features of different reactor types focusing on PWR And BWR features in fuel design, enrichm e nt, number of pins per assem b ly and num b er of assem b lies.

41-44 Reactor Phy sics Review – Neutr on cross sections – em phasize the Possibilities for neutr on iteraction – each with its own likelihood of occurrence. Discuss energy dependence on cross section using uranium 235 and 238 as exam ples – explain resonance regions and how i m portant it is for th erm al reacto r s to have en ough neutro ns to survive the absorption an d scatte ring to end up in the therm a l energy range. Here is w here the selection of m a terials m a tters for the core.

45 Fission chain reaction – summarize th e possibilities for absorption

And scattering so the enough neutrons survive. – explain criticality and subcriticality.

46-52 Discuss the energy of fissioned neutrons – spectrum and how the 200 Mev per fission is achieved whic h m ust be removed from the core. Exam ine the fission produc t m a ss distribution showing how the fission products contribute to neutron absorption affecting the num b er of neutrons av ailable fo r fission. Review decay chain s using the chart of nuclides that need to be tracked in core physics analys is.

53 Conclude with a brief discussion of reaction rates in term s of what Is the governing equation for power production and key issues in how long a core can operate – fu el depletion, boron or burnable poison loading, reactivity swing, re fueling strategies. Engage in discussion of how to design a core to fit the power needs.

MIT OpenCourseWare http://ocw.mit.edu

22.091 / 22.903 Nuclear Reactor Safety

Spring 200 8

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