Teachin g Notes
Operationa l Reacto r Safet y Course
Lecture : 1 0 – Safet y Analysi s Repor t an d LOCA
Objective :
To gain an appreciation of what goes into a safety analys is report and the Chapte r 15 trans i ents an d acciden t s that are an aly zed. The analysis resu lts of a typical loss of coo l ant acciden t are reviewed.
Ke y Point s t o Brin g Out:
Slid e num be r Point s
3 Identifies som e to the key fission pro ducts that are of concern in an acciden t situ ation and w hy they need to be contained.
4 The m e ssage here is that sim ply shutting down the reactor is not sufficient to prevent co re dam age - decay heat m u st be rem oved.
5 Critical safety functions should be ex plained s i nce this is the way most reacto r s are now maintain ing safety of their plants.
6-11 A basic review of PWR engineered safety system s that describes each system individually.
12 Sa m e description of a BWR engin eered safety sy stem s - repe at.
13-17 Begins the review of NRC requirem e nts and criteria for reactor design - siting criteria which is dose based. General design criteria, single failure criteria. E n courag e students to go to the NRC web site to read the specific g u idance pro v ided.
18-20 Defense in Depth is described in som e detail and how safety strategies are im ple m ented consis tent with this philosophy. Be sure to point out defense in depth is not sim ply counting physical barriers but more of system atic approach to safety.
21 Review chapter of a typical safety analysis report - if you have one show it to the students.
22-26 Review design basis accidents as req u ired f o r the Chapter 15 safety analysis report. L e vel of detail provided is intended to show the rigo r of the analys is and range of acciden t s an d trans i ents considered.
27-28 ECCS criteria for LOCA and schem a tic of what is postulated. All the criteria must be shown to be m e t - focus on 2200 F peak clad tem p erature with loss of of f site power and m o st dam a ging single f ailure.
28 The purpose of this slide is to show the events th at need to take place to assu re proper function - the event tree also begins to introduce the concept of probabilistic vs determ i nistic analysis as required by the regulations today f o r this even t.
30-47 This series of slides goes through an exam ple of a LOCA ana l ysis beginning w ith reactor protective se t points on slide 30. This slide is im portant since it shows what is needed to shutdown the reactor autom a tically based on system conditions. A LOCA indicator could be low pressure (large break ) or high containm ent pressure - sm all break or ECCS initiation.. Rev i ew these s l ide to give th e students an appreciation of how fa st things happen in an LWR. This is a P W R sequence. Various break sizes are shown with different peak clad tem p erature resu lts. The last f e w slides co m e from the FSAR to describe the results shown for the studen t s.
MIT OpenCourseWare http://ocw.mit.edu
22.091 / 22.903 Nuclear Reactor Safety
Spring 200 8
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