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Calculating Nuclear Power Plant Vulnerability Using Integrated Geometry and Event/Fault Tree Models. ANS/EP&R Washington, DC November 20, 2002. Douglas E. Peplow, C. David Sulfredge, Robert L. Sanders, and Robert H. Morris
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Calculating Nuclear Power PlantVulnerability Using Integrated Geometry andEvent/Fault Tree Models ANS/EP&R Washington, DC November 20, 2002 Douglas E. Peplow, C. David Sulfredge, Robert L. Sanders, and Robert H. Morris Oak Ridge National Laboratory Todd A. Hann Defense Threat Reduction Agency
Terrorist Attacks Against American Targets Using Car-Bomb Technology
Event/Fault Tree Models and Geometry Models
Approaches to Blast Modeling • Hydrocode modeling • Detailed, first-principles analysis • Complex computer codes (CTH, DYNA-3D, FLEX, etc.) • Long computer run times • Correlation modeling • Based on experimental test data • Results given using scaled parameters • Quick, with good general accuracy
Early Nuclear Blast Testing • Nuclear tests at Nevada Test Site measured the blast resistance for many types of industrial and utility equipment
Scaling Laws Allow Data Correlation • Hopkinson scaling parameters • P = F1( R/w1/3) • I/w1/3 = F2( R/w1/3) • t/w1/3 = F3( R/w1/3) • Also known as “cube root” scaling
Reflective Blast Enhancement • Correlations can account for effect of walls surrounding the charge
VISAC Concrete Breach Models • NDRC experiments for air blast against concrete walls
Overpressure Fragility Curves • Critical components require fragility functions • Plot of Pkill versus peak overpressure • Either linear or logarithmic interpolation
For Independent Events… • P = P1P2…PJ • P = ΣPi – ΣPiPj + … ± P1P2…PJ = 1 - (1-P1)(1-P2)…(1-PJ)
Event/Fault Tree Evaluation • Brute Force • Monte Carlo • Minimal Cut Set Analysis • Rare Events Approximation • Upper Bound • Exact with Passes
Minimal Cut Sets • Sequence = E3E4 + E1E2E5 + E1E4E5 + … = C1 + C2 + C3 + … • P(Seq.) = ΣP(Ci) - ΣP(CiCj) + ΣP(CiCjCk) - … ~ ΣP(Ci) < 1 – (1-P(C1))(1- P(C2))(1- P(C3))…
seq1 = /ecs = /epumpa /emova /ecva /tank /dga /emov1 + /tank /dga /ecvb /emov1 /emovb /dgb /epumpb SAPHIRE Example Problem seq2 = ecs /ccs = ecva emovb /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + ecva epumpb /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + epumpa emovb /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + epumpa epumpb /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + emova ecvb /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + emova emovb /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + emova emovb /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + ecva ecvb /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + emova epumpb /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + ecva ecvb /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + emov1 /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + epumpa epumpb /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + epumpa ecvb /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + ecva emovb /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + ecva epumpb /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + emova ecvb /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + emov1 /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + epumpa emovb /cmov1 /tank /ccvb /cmovb /cpumpb /dgb + emova epumpb /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + epumpa ecvb /cmov1 /tank /dga /cmova /ccva /cpumpa /dgb + dga /cmov1 /tank /ccvb /cmovb /cpumpb /dgb
Summary • Correlations using real data are faster than hydrocode calculations yet still accurate • Need fault/event tree calculator that handles large component failure probabilities • Geometric fidelity is important in obtaining useful results