Siemens Bump Test Assessment and Response to Customer Concerns

1. CT3 – Bump Test:Siemens Assessment and Response to Customer Concerns • Agenda: • New Design Inlet Strut Configuration • Issue of Concern • Bump Test Instrumentation Configuration • - Bump Test Results • Assessment Of Test Protocol • Siemens Assessment of Test Results • Strut #9 Post Modification Bump Testing Results – System Mode • Strut #9 Post Modification Bump Testing Results – Strut First Bending Mode • Comments / Conclusions

2. W501F Inlet Strut New Design Configuration Description • New Design Configuration Description: • New struts is Z shape strut design to improve stress and vibratory characteristic • Bolted flanges to eliminate the weld pipe to the manifold wall. • The size of the pipes is the same as the baseline, nominal pipe size 2.500x0.276 wall - SCH 80 .

3. New Design Inlet Strut Installed

4. Issue of Concern Excerpted from e-mail:, et.al dated 2/16/07: “…..Our testing shows that the new design still has a design resonance of roughly 60 Hz at the #2 & #9 positions and not 72-75 Hz as promised.”

5. Bump Test Instrumentation Configuration From “Unit 3 – Inlet Strut – Resonance Testing” Report date 2/12/07: TEST PERFORMED: Single channel impact test using CSI-2130 vibration data analyzer and 100 mv/g accelerometer. Accelerometer was positioned in the horizontal plane at the midpoint of each individual strut.

6. CT3 – Bump Test Results From “Unit 3 – Inlet Strut – Resonance Testing” Report date 2/12/07: Resonant Frequency Not Increased!

7. Assessment Of Test Protocol • Bump Test Protocol: Siemens Assessment: • A greater number of accelerometers are required on the strut as well as the end walls in order to adequately characterize vibration modes. A total of 15 – 20 per strut / wall is recommended • Change spectral range to 0 – 250 Hz so that lower frequency vibratory modes of concern can be distinguished • Post process data with lab software to animate mode shapes so that strutfirst bending mode can be discerned from system vibration modes • Conclusion: • Bump Test protocol was not adequate to measure the first strut bending mode. Hypothesis: a system mode was most likely measured and mistakenly attributed to the strut first bending mode.

8. Siemens Test Data Confirms Wall Mode At 66 Hz • Siemens performed a post modification bump test during April 2006 to verify the operational test results and analysis prediction • Siemens has performed vibration testing that confirms the presence of a system mode associated with the New Design Strut #9 • The “System Mode” was measured at 66 Hz (see following slides) • The same testing confirmed the new design First Bending mode frequency of ~ 75 Hz.

9. Strut #9 Post Modification Siemens Accelerometer Testing Results – Wall Mode Mode at ~ 66 Hz is a “system mode” Strut Rigid body motion

10. Strut #9 Post Modification Siemens Accelerometer Testing Results – First Bending Mode Mode at ~ 75 Hz is the strut first Bending Mode

11. Conclusions and Comments • Siemens believes that The Bump Testing Protocol did not accurately measure the first strut bending mode • Siemens hypothesized that essentially unchanged pre to post mod frequencies measured by XXX were the result of an existing system mode that would not be expected to change with the new design strut • Siemens testing confirms the presence of a system mode at 66 Hz. This confirms the initial hypothesis. • Previous Siemens testing has also confirmed the 75 Hz first strut bending mode frequency for struts #2 and #9. • Although Siemens does not feel that additional testing is required, we are available to perform a proper bump test as well as subsequent data analysis (funded by the customer).