THE SAFETY IN DEPTH CONCEPT. FUNCTIONAL DESIGN AND ACCIDENT SCENARIO IN NET APPLIED TO A BREEDING BLANKET ACCIDENT ANALYSIS
Safety in depth is a very efficient strategy to attain a given level of protection in a new design. It consists in optimizing a set of protective barriers, both active and passive, between sources of hazard and people or equipments. This approach requires, from the very beginning of NET design, the definition as complete as possible, of each plant's systems. At present a functional design is in progress for the systems which play a major role with regard to safety. It consists of: - the definition of the system's functions and of its interfaces; - the possible accident initiators within the system; - the accident deployment to the adjacent systems; - the required diagnostics and protection systems; - the system's performances in normal and accident conditions; - the further step (not yet developed at this stage) includes the setting of the reliability level of each function and operating mode (i.e. of the components which insure them). An application is shown to a NET relevant system, a proposed blanket with Li-17Pb-83 breeder and pressurized water as coolant. The analysis considers the following topics: - the functional design of the blanket and choice of a pipe break as typical accident initiator; - accident scenario, related to this initiator, which includes: . the mechanical behaviour of a blanket modulus. The input transient pressure is taken from experimental results of Li-17Pb-83 - water interaction. The 2-D nonlinear dynamic calculations, with fluid structure interaction, show that the loss of containment is a very low probability event; . the consequences in terms of radioactive release (activated corrosion products and tritium) have been evaluated in the unlikely event of modulus shell rupture; . the assessment of the required characteristics for the next protective barrier, i.e. the outer shell of the blanket segment. This procedure will be extended to the other NET systems allowing a safety-oriented choice among different design options. The final purpose is to obtain a NET accident envelope in terms of hazard (from radioactive releases) to the operators and pollution at large.
Bibliographic Reference: 13TH SYMPOSIUM ON FUSION TECHNOLOGY, VARESE (ITALY), SEPT. 24-28, 1984 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 31614 ORA
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Record Number: 1989123062200 / Last updated on: 1987-01-01
Available languages: en