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Title: NDE Studies on CRDMs Removed From Service

Abstract

Studies being conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington are focused on assessing the effectiveness of NDE inspections of control rod drive mechanism (CRDM) nozzles and J-groove weldments. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the effectiveness of ultrasonic testing (UT) and eddy current testing (ET) as related to the in-service inspection of CRDM nozzles and J-groove weldments, and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC) through destructive characterization of the CRDM assemblies. In describing two CRDM assemblies removed from service, decontaminated, and then used in a series of NDE measurements, this paper will address the following questions: 1) What did each technique detect?, 2) What did each technique miss?, 3) How accurately did each technique characterize the detected flaws? Two CRDM assemblies including the CRDM nozzle, the J-groove weld, buttering, and a portion of the ferritic head material were selected for this study. One contained suspected PWSCC, based on in-service inspection data; the other contained evidence suggesting through-wall leakage, but this was unconfirmed. The selected NDE measurements follow standard industry techniques for conducting in-service inspections of CRDMmore » nozzles and the crown of the J-groove welds and buttering. In addition, laboratory based NDE methods will be employed to conduct inspections of the CRDM assemblies, with particular emphasis on inspecting the J-groove weld and buttering. This paper will also describe the NDE methods used and discus the NDE results. Future work will involve using the results from these NDE studies to guide the development of a destructive characterization plan to reveal the crack morphology, to be compared with NDE responses.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
948427
Report Number(s):
PNNL-SA-44655
401001060; TRN: US0901635
DOE Contract Number:
AC05-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT 18), 4217-4229, Art. No.: SMiRT18-O05-1
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; CONTROL ROD DRIVES; DEFECTS; EDDY CURRENT TESTING; IN-SERVICE INSPECTION; KNOWLEDGE BASE; MORPHOLOGY; NOZZLES; REACTOR TECHNOLOGY; STRESS CORROSION; ULTRASONIC TESTING; WATER; TOFD; VT; UT; ET; NDE; CRDM; PWSCC

Citation Formats

Doctor, Steven R., Cumblidge, Stephen E., Schuster, George J., Hockey, Ronald L., and Abrefah, John. NDE Studies on CRDMs Removed From Service. United States: N. p., 2005. Web.
Doctor, Steven R., Cumblidge, Stephen E., Schuster, George J., Hockey, Ronald L., & Abrefah, John. NDE Studies on CRDMs Removed From Service. United States.
Doctor, Steven R., Cumblidge, Stephen E., Schuster, George J., Hockey, Ronald L., and Abrefah, John. Sat . "NDE Studies on CRDMs Removed From Service". United States. doi:.
@article{osti_948427,
title = {NDE Studies on CRDMs Removed From Service},
author = {Doctor, Steven R. and Cumblidge, Stephen E. and Schuster, George J. and Hockey, Ronald L. and Abrefah, John},
abstractNote = {Studies being conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington are focused on assessing the effectiveness of NDE inspections of control rod drive mechanism (CRDM) nozzles and J-groove weldments. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the effectiveness of ultrasonic testing (UT) and eddy current testing (ET) as related to the in-service inspection of CRDM nozzles and J-groove weldments, and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC) through destructive characterization of the CRDM assemblies. In describing two CRDM assemblies removed from service, decontaminated, and then used in a series of NDE measurements, this paper will address the following questions: 1) What did each technique detect?, 2) What did each technique miss?, 3) How accurately did each technique characterize the detected flaws? Two CRDM assemblies including the CRDM nozzle, the J-groove weld, buttering, and a portion of the ferritic head material were selected for this study. One contained suspected PWSCC, based on in-service inspection data; the other contained evidence suggesting through-wall leakage, but this was unconfirmed. The selected NDE measurements follow standard industry techniques for conducting in-service inspections of CRDM nozzles and the crown of the J-groove welds and buttering. In addition, laboratory based NDE methods will be employed to conduct inspections of the CRDM assemblies, with particular emphasis on inspecting the J-groove weld and buttering. This paper will also describe the NDE methods used and discus the NDE results. Future work will involve using the results from these NDE studies to guide the development of a destructive characterization plan to reveal the crack morphology, to be compared with NDE responses.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Dec 31 00:00:00 EST 2005},
month = {Sat Dec 31 00:00:00 EST 2005}
}

Conference:
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  • Studies being conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington are being performed to assess the effectiveness of nondestructive examination (NDE) techniques on removed-from-service control rod drive mechanism (CRDM) nozzles and the associated J-groove attachment welds. This work is being performed to provide information to the United States Nuclear Regulatory Commission (US NRC) on the effectiveness of NDE techniques such as ultrasonic testing (UT), eddy current testing (ET), and visual testing (VT) as related to the in-service inspection of CRDM nozzles and J-groove weldments, and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC)more » through destructive characterization of the CRDM assemblies. The basic NDE measurements follow standard industry techniques for conducting in-service inspections of CRDM nozzles and the crown of the J-groove welds and buttering. In addition, laboratory-based NDE methods were employed to conduct inspections of the CRDM assemblies, with particular emphasis on the J-groove weld and buttering. This paper describes the NDE measurements that were employed on the two CRDMs to detect and characterize the indications and the analysis of these indications. The two CRDM assemblies were removed from service from the North Anna 2 vessel head, including the CRDM nozzle, the J-groove weld, buttering, and a portion of the ferritic head material. One nozzle contains suspected PWSCC, based on in-service inspection data; the second contains evidence suggesting through-wall leakage, although this was unconfirmed. A destructive test plan is being developed to directly characterize the indications found using nondestructive testing. The results of this destructive testing will be included when the destructive testing is completed.« less
  • Studies conducted at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington focused on assessing the effectiveness of nondestructive examination (NDE) techniques for inspecting control rod drive mechanism (CRDM) nozzles and J-groove weldments. The primary objective of this work is to provide information to the United States Nuclear Regulatory Commission (US NRC) on the effectiveness of NDE methods as related to the in-service inspection of CRDM nozzles and J-groove weldments, and to enhance the knowledge base of primary water stress corrosion cracking (PWSCC) through destructive characterization of the CRDM assemblies. Two CRDM assemblies were removed from service, decontaminated, and thenmore » used in a series of laboratory NDE and DE measurements; this report addresses the following questions: 1) What did each NDE technique detect?, 2) What did each NDE technique miss?, 3) How accurately did each NDE technique characterize the detected flaws?, and finally 4) What were the basis for the NDE techniques performance? Two CRDM assemblies including the CRDM nozzle, the J-groove weld, buttering, and a portion of the ferritic head material were selected for this study. This paper focuses on a CRDM assembly that contained suspected PWSCC, based on in-service inspection data and through-wall leakage. The laboratory NDE measurements used to examine the CRDM assembly followed standard industry techniques for conducting in-service inspections of CRDM nozzles and the crown of the J-groove welds and buttering. These techniques included eddy current testing, time of flight diffraction ultrasound, and penetrant testing. In addition, other laboratory-based NDE methods were employed to conduct inspections of the CRDM assembly with particular emphasis on inspecting the J-groove weld and buttering. These techniques included volumetric ultrasonic inspection of the J-groove weld metal, visual testing via replicant material of the J-groove weld and high resolution photography of the J-groove weld crown and buttering. The results from these NDE studies were used to guide the development of the destructive characterization plan. The NDE studies found several crack-like indications. The NDE and DE studies determined that one of these was a through-weld radially-oriented PWSCC crack in the wetted surface of the J-groove weld, located at the transition point between the weld and the buttering. The crack was 6 mm long on the surface and quickly grew to 25 mm long at a depth of 8 mm, covering the length of the weld between the penetration tube and the carbon steel. The NDE studies found that only ET was able to detect the through-weld crack. The crack was oriented poorly for the ultrasonic testing, and was too tight for accurate PT or VT. The ET voltage response of the flaw was 30% that of a deep EDM notch. The DE performed on the crack consisted of slicing the crack into thin sections, polishing the sections, and then using optical and scanning electron microscopy (SEM) to characterize the crack. DE shows the crack was PWSCC and that it initiated on the wetted surface, grew and expanded through the weld metal, and exited into the annulus. The SEM examinations showed the crack followed the weld grain boundaries as it progressed through the weld. The crack was branched and discontinuous along its length.« less
  • Battery failure modes are described. Data is presented from survey results on 12-volt automotive passenger car batteries. The age from manufacturing code was determined. Failures were classified into the following categories: serviceable, broken, open circuit, short circuit, corrosion, worn out, abused, or overcharged.
  • Stress-corrosion cracks produced in high-temperature water environments were examined in alloy 600 and stainless steel samples. The alloy 600 samples were removed from pressurized-water reactor (PWR) steam generator tubing after exhibiting cracking in service or after model-boiler stress corrosion cracking tests. The 304 and 316 stainless steel samples also experienced intergranular stress corrosion cracking (IGSCC) in high-temperature-water environments similar to a PWR steam generator. Grain boundary misorientations were measured along IG crack paths as well as in the bulk. In general, only twin Sigma 3 boundaries exhibited improved resistance to crack propagation. If the Sigma 3 were factored out, themore » fractions of grain boundary types of cracked boundaries corresponded to their frequency of occurrence in the bulk alloy. Other boundaries with coincident site lattice misorientations, including Sigma 9 and Sigma 27, were observed to crack. The cracks were often (but not always) arrested at grain boundary junctions containing Sigma 3 boundaries. The results obtained indicate that grain boundary crystallography does not fully determine its susceptibility to IGSCC in typical commercial alloys. Other factors must be taken into account when assessing material?s propensity to IG failure.« less