1 V&V: What to Expect When You’re Doing Science Karen Pao Division of Advanced Simulation and Computing (ASC) Office of R&D for National Security S&T National Nuclear Security Agency (NNSA) US Dept of Energy

2 You have the opportunity to do things in the right order… We wished we had better experiments for V&V!

3 The ASC program has a V&V subprogram – a rarity in simulation programs!

4 Where others think the NNSA is today Consider the JASON RRW report – even though it never explicitly mentioned V&V: –“…A concern remains, however, that even though codes can reproduce the performance of previously tested weapons, it is not yet possible to quantify how well excursions from a tested design can be modeled and predicted…” This and other concerns led to a new Congressional direction to establish the “Advanced Certification” Campaign to address: –improvement of the weapons certification process through expanded, independent peer review mechanisms and refinement of computational tools and methods; –advancement of the physical understanding of surety mechanisms; –further exploration of failure modes; –manufacturing process assessments; and –the study of strategic system-level requirements. Is Science-Based Stockpile Stewardship a house of cards?

5 You might not see the V&V, but it has to be there Not to Scale Code and Model Development Applications (design/analysis) V & V is the backbone of all simulations, the pervasive evaluator

6 We have a Vision for V&V Assess Simulation Credibility Advise Simulation Community Advocate Simulation Capability

7 Consequences of simulations Important national security decisions will be made based on, ultimately, simulations –A person will make the decision. What evidence will the person possess? Some examples of decisions that would, could, or should be made with help from simulations: –Annual Assessment: stockpile systems are evaluated to determine whether or not the Nation needs to go back to underground nuclear testing –Evaluation of the “Preferred Alternative” of NNSA’s “Complex Transformation:” When does the Nation need a particular facility to build particular parts? –Consequence Management: planning for an urban detonation event – high- fidelity simulations will help planners, first-responders, and decision-makers determine what will be done in such an event What would it take for someone to believe simulation results – enough to make a decision based on them?