Flow Measurements Pitot Versus Tracer - A Utility Perspective Phil Gernenz Exelon – Braidwood Station Based upon Control Room Envelope Tracer Gas testing December 2004

Emergency Make Up Air Flow Measurements A-train: Tracer Gas: 5004 SCFM Hot Wire: 5847 ACFM Pitot/Manometer: 6230 ACFM B-train: Tracer Gas: 4914 SCFM Pitot/Manometer: 5901 ACFM Pitot/Manometer 20% higher than Tracer Gas

Converting Flows to ACFM A-train:B-train: Tracer Gas: 5607* 5437* Pitot: Hot Wire: 5847N/A Still not the same…… * The flow used for the final tracer gas test results was taken upstream of the filter unit. The flows referenced on this page were based upon tracer gas test measurements taken at the pitot traverse which is located downstream of the filter unit. The difference between upstream and downstream of the filter unit was about 30 SCFM.

Incorporating tolerances Tracer Gas using ANSI/ASME Standard Uncertainty Model. Pitot / Hotwire using +/-10% per ANSI N (ACFM)A-trainB-train Tracer Gas Pitot Hot Wire

UFSAR/Technical Specification Requirements References Regulatory Guide 1.52 Revision 2 and ANSI N ANSI N establishes airflow acceptance criteria in accordance with ACGIH Industrial Ventilation Section 9. Industrial Ventilation provides guidance for using the pitot traverse methodology involving the equal area method. Therefore, use of the pitot traverse is consistent with Braidwood's licensing basis requirements.

Review of the Pitot Traverse The duct dimension was 18” x 28” +/- 1/8” No interferences (structural members) could be found internal to the duct The pitot traverse meets the requirements of a satisfactory distribution as defined in Industrial Ventilation Section 9 (75% readings greater than 0.10(maximum VP)). HOWEVER:

Review of the Pitot Traverse The required distance downstream of the nearest air disturbance such as an elbow should be 7.5 duct diameters. The pitot traverse should be at 15 feet 4 inches downstream of the nearest upstream elbow. On A- train the distance is 14 feet 1 inch (less than recommended distance). On B-train the distance is 15 feet 8 inches. The minimum recommended number of traverse points is 16. The pitot traverses used has only 15 points (less than recommended number).

New traverses created A-train Traverse A) Original Pitot Traverse: 14’1” downstream of elbow Traverse B) New Traverse using Log –Tchebycheff Method: 23’ downstream of elbow Traverse C) New Traverse using Equal Areas (28 points): 23’ 8” downstream of elbow B-train Traverse A) Original Pitot Traverse: 15’8” downstream of elbow Traverse B) New Traverse using Log –Tchebycheff Method: 22’ 7” downstream of elbow Traverse C) New Traverse using Equal Areas (28 points): 23’ 3” downstream of elbow

Results of Different Traverses Flows (ACFM) were taken using a 0-10iwg inclined manometer and Shortridge (ADM- 80) in conjunction with a pitot tube. Train A: Traverse # of ManometerShortridge % Difference points A % B % C % % Difference2.2%2.3% Train B: Traverse # of ManometerShortridge % Difference points A % B % C % % Difference1.6%2.7%

OPEX Plant Event #34480 (1998) – Plant was using Orifice Plate for flow measurement to meet Technical Specification requirement, however, Technical Specification flow measurement was to be in accordance with ANSI N which requires that the pitot traverse be used. Event Number (1998) - Plant was using Hot Wire for flow measurement to meet Technical Specification requirement, however, Technical Specification flow measurement was to be in accordance with ANSI N which requires that the pitot traverse be used. OE19047 (2004) – Plant Technical Specifications specified “SCFM” as opposed to “CFM”. Design and regulatory Guidance specified flowrate in “CFM”.

Conclusion Ensure you are obtaining data in accordance to your Licensing Basis as required.

Flow Profiles