Update Status of Crossflow following US-NRC RIS

Beginning in 2004 the US-NRC conducted a review of Ultrasonic Flow Meter (UFM) technology.  In 2007 the US-NRC issued a Regulatory Issue Summary (RIS) to the CROSSFLOW users stating:

  • Current CROSSFLOW users can continue to operate the UFM with no new requirements or specific actions needed. All plants using the system may continue to do so for either Appendix K (Measurement Uncertainty Recapture –MUR) or Power Recovery.
  • Approval for the use of the Topical Report was withdrawn for NEW license applications until the issues identified by the US-NRC are addressed in a revised Topical Report.
  • The five issues (weaknesses) identified that must be addressed in the new Topical Report are shown below.

US-NRC Issue: Transferability of laboratory calibration to an in-plant configuration.
Resolution Status: Resolved. New enhanced multi-beam instrument with enhanced signal processing capability will enable the transference of the laboratory calibration to the plant while maintaining traceability.

US-NRC Issue: Ability to detect and correct for acoustic noise.
Resolution Status: Resolved. CROSSFLOW Software version 4.2 implements noise detection and correction.

US-NRC Issue: Lack of periodic in-plant calibration traceable to a national standard and assurance that CROSSFLOW operation remains within the claimed uncertainty.
Resolution Status: Resolved. The enhanced instrument design addresses both these issues.

US-NRC Issue: Lack of specific restrictions where CROSSFLOW calibration can be considered valid.
Resolution Status:  Resolved. The installation procedure of the enhanced instrument defines these restrictions. Checks for out-of-limit conditions will be implemented.

US-NRC Issue: Inadequate description of installation and use of CROSSFLOW.
Resolution Status: Resolved. New updated User Guideline document issued.


No plant required to take CROSSFLOW out-of-service.
Plants continue to use CROSSFLOW for Appendix K MUR and Power Recovery applications as well as many other applications (ECCS, Service Water, Feeders, Turbine Testing, etc.)

New enhanced multi-beam design and enhanced digital signal processing capabilities resolve issues with transfer of laboratory calibration to plant, maintenance of calibration and traceability to a National Standard.

A new Topical Report addressing the issues identified by the US-NRC is being prepared for Regulatory approval.