Teachin g Notes
Operationa l Reacto r Safet y Course
Lecture : 9 – Safet y System s an d Functions
Objective :
To review the fundam e nt als of nuc lear reactor safety and what goes into a safety analysis. Design basis acciden t s are rev i ew ed as are the safety s y stem s needed to m itigate acciden t s. Introduce the concept of defense in depth and the role of containm ent in the overall strategy of protection of the public. Follow Knief Chapter 13.
Ke y Point s t o Brin g Out:
Slid e num be r Point s
3 Be sure students understand the difference between prevention, protec tion a nd m itigatio n and conce p t of def ense in depth w h ich is the foundation of safety.
4-5 Establish the source of energy that need to be m a naged with the safety m i ssion of heat removal to avoid, if possible, fuel failure and rele ases. Last m itigating m easure is of f site emergency response.
15 Explain what a design basis accident is and how they are m eant to assure that the plant is safe. Gene ral catego r ies that are inten d ed to cover m o st events that might be expected to occu r during the life of the plant.
16 Point out the possible energetic reactions that need to be considered in design to address possible consequences - focus on Hydrogen and zirconium reactions for water reactors.
17 Review the com p lete schem a tic of a t PW R identifying key com ponents in the power cycle - point out difference in prim a r y and secondary side. Exp l ain th e function of each com ponent and system .
18 Review specific design basis acci dents asking students what m i ght
happen in th e event in te rm s of what will happen with reac tiv ity, cooling co re, core tem p erature, pressure. Explain that these analyses are required by the NRC to be determ inis tically analy zed under specific conditions which ar e specified. (such as Appendix K for LOCA).
10 Point out engineered safety features - explain functions of containm ent spray, accu mulator, hig h and low pressure s a fety injection and source of water for ECCS functions including sum p recirculation .
11-12 Review Beyond Design Basis Accide nts types includi ng core m e lt scenarios and the availab ility of fission products f o r release in core m e lt acciden t s which is why they need to be avo i ded.
13 Go over the details of what ha ppens in the event of a loss of coolant accident in terms of how one m i ght get a release from containm ent upon failure of the em er gency safeguards system s.
14-15 Go over the graphic of engineered safety system s followed by the slide showin g what they are in a PWR.
16-17 The role of the Containm ent shoul d be described here with the potential consequences of loss of containm ent sprays in PWRs on containm ent integr ity due to overpressure.
18-20 Review engineered safety features for BW Rs noting a different design for core and containm ent sprays. ECCS water goes directly into the v ess el at the top of th e core. LOCA blow down goes into inerted water suppression pools with heat rem oval system s needed to rem ove heat from the suppressi on pool. Other slides show more advanced BWR syste m s using sam e concept.
21 Containm ent leakag e an d what is actually released in the event of an acciden t s should be d i scussed h e re.
MIT OpenCourseWare http://ocw.mit.edu
22.091 / 22.903 Nuclear Reactor Safety
Spring 200 8
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