ML19010A071

Impending Publication Memo for Modeling Simulation Tlr (PNNL-28362)

ML19010A071
Person / Time
Issue date:	01/11/2019
From:	Bernard Thomas Office of Nuclear Regulatory Research
To:	Joseph Donoghue Office of Nuclear Reactor Regulation
Nove C
Shared Package
ML19010A070	List: ML19010A071 ML19010A072
References
PNNL-28362
Download: ML19010A071 (3)

Text

January 11, 2019 MEMORANDUM TO: Joseph E. Donoghue, Acting Director Division of Materials and License Renewal Office of Nuclear Reactor Regulation FROM: Brian E. Thomas, Director /RA/

Division of Engineering Office of Nuclear Regulatory Research

SUBJECT:

IMPENDING PUBLICATION OF TECHNICAL LETTER REPORT ENTITLED ULTRASOUND MODELING AND SIMULATION: STATUS UPDATE (PNNL-28362) (UNR NRR-2013-009)

The Office of Nuclear Regulatory Research (RES) has completed a technical letter report entitled Ultrasound Modeling and Simulation: Status Update, (ADAMS Accession ML18331A254) under contract with Pacific Northwest National Laboratory. This Technical Letter Report (PNNL-28362) documents work performed under Task 1, Modeling, in User Need Request (UNR) NRR-2013-009 Evaluating the Reliability of Nondestructive Examinations of Vessels and Piping. This UNR focuses on assessing the reliability and effectiveness of nondestructive examination methods used in nuclear power plants. Specifically, Task 1, Modeling, will provide the Office of Nuclear Reactor Regulation (NRR) with the technical basis to appropriately evaluate the adequacy of licensee submittals that utilize ultrasonic modeling.

Further, the task will provide guidance as to how ultrasonic models, sound maps, and simulated flaw responses should be carried out and interpreted when applied to a variety of materials and degradation mechanisms.

The Modeling Task is divided into three phases. PNNL-26336, a TLR entitled Validation of Ultrasonic Nondestructive Examination (NDE) Computational Models - Phase 1, (ADAMS Accession ML17082A190, documented the results of PNNLs studies of simple geometrical reflectors in isotropic, fine-grained, homogeneous materials examined with conventional ultrasonic transducers. Modeling of the ultrasonic testing was conducted with CIVA software, and predictions were compared to the empirical data both qualitatively and quantitatively. This TLR, PNNL-28362, provides a summary of the second phase of the study being performed to validate the computational models for ultrasonic testing, and determine if ultrasonic computational models adequately represent reality. The primary objectives of the work described in this TLR were to evaluate the effectiveness of beam models with respect to quantifying volumetric coverage and flaw detection capability, and to evaluate both beam models and flaw response models for simulating welded geometries. Included in the evaluation was the identification of key variables in typical simulation models that influence coverage extent and flaw detection capability.

CONTACT: Carol A. Nove, RES/DE/CIB (301) 415-2217

J. Donoghue For this second phase of the modeling and simulation study, a comparison of two different commercially available software simulation tools was conducted to obtain a baseline indication of the variability of results across different simulation software packages. The results observed in this comparison suggest several factors may influence the computed beam profiles, of which only the parameters representing the transducer are controllable by the user. A key recommendation from the work is that the software capabilities and limitations be better understood prior to using simulation software to estimate flaw detection capability. Thus, users attempting to employ any simulation software will have an understanding of the models implemented and the resulting capabilities and limitations of these models prior to drawing conclusions. Further, while beam models in isotropic materials are reasonably accurate (regardless of the software tool used), their use in anisotropic or complex microstructures is more challenging. Results on a limited set of austenitic weldments indicated that the computed beam profiles through the welds were qualitatively in agreement with experiments; however, the accuracy of the simulation appeared to depend on the accuracy with which the weld material properties can be established.

At this time, the PNNL modeling and simulation study is transitioning into Phase 3, where ultimately a standard method for NRC to use to evaluate ultrasonic simulations will be developed and documented in a Regulatory Guide that synthesizes all that was learned via the three phase modeling and simulation program. This standard method is important as the U.S.

nuclear industry is beginning to rely on ultrasonic simulations as a basis to demonstrate that the examination techniques applied are acceptable. Specifically, the NRC has received relief requests where simulations were used to justify the ability to detect service-induced, surface-breaking cracks when limited coverage of the required ultrasonic inspection volume occurs.

The PNNL modeling & simulation work will enable the NRC to confirm that a solid technical basis for conducting, interpreting and applying the results of ultrasonic simulations exists, and, further, that the licensee simulations provide an acceptable level of quality and safety.

Staff representatives from the Division of Materials and License Renewal in NRR reviewed a draft of this TLR, and the enclosed final TLR reflects the resolution of their comments.

Nonetheless, please feel free to notify the responsible RES contact if you have any questions concerning the impending public release of this TLR.

RES has established an online quality survey to collect feedback from user offices on the usefulness of RES products and services. This survey can be found online at the hyperlink:

http://fusion.nrc.gov/res/team/OfficeWide/Lists/RES%20Product%20Quality%20Survey/overvie w.aspx. I would appreciate the responsible manager or supervisor completing this short survey within the next 10 working days to present your offices views of the delivered RES product.

If additional information is required, please contact Carol A. Nove of my staff at 301-415-2217 or can2@nrc.gov.

Enclosure:

As stated

J. Donoghue

SUBJECT:

IMPENDING PUBLICATION OF TECHNICAL LETTER REPORT ENTITLED ULTRASOUND MODELING AND SIMULATION: STATUS UPDATE (PNNL-28362) (UNR NRR-2013-009)

DISTRIBUTION:

S. Ruffin, NRR D. Alley, NRR S. Cumblidge, NRR D. Rudland, NRR J. Honcharik, NRO E. Reichelt, NRO R. Furstenau, RES B. Lin, RES L. Smith, RES ADAMS Package Accession No.: ML19010A070 OFFICE RES/DE RES/DE RES/DE NAME C. Nove R. Iyengar B. Thomas DATE 01/ 08 /19 01/ 08 /19 01/ 11 /19 OFFICIAL RECORD COPY