Three-dimensional pantograph for use in hazardous environments

Material measurement device is used with radioactive probes which can be approached only to distance of 3 feet. Tracer-following unit is capable of precisely controlled movement in X-Y-Z planes. Pantograph is usable in industrial processes involving chemical corrosives, poisons, and bacteriological hazards, as well as nuclear applications

Electronic flaw simulator for eddy current probe calibration

Electronic flaw simulator cycled into the eddy current system eliminates errors in probe calibration. A discrimination level reference established in the probe permits recognition of those flaws in materials with an equivalent volume equal to or greater than the reference

Experimental and theoretical studies of the reaction of atomic hydrogen with silane

Article on experimental and theoretical studies of the reaction of atomic hydrogen with silane

The development of code inservice inspection (ISI) requirements for Low Temperature Heavy Water Reactors (LTHWR)

DOE Savannah River Field office requested that the American Society of Mechanical Engineers (ASME) develop rules for inservice inspection (ISI) of Savannah River Site (SRS) Low Temperature Heavy Water Reactors (LTHWR's) in January 1990. The request is part of the SRS Reactor Safety Improvement Program (RSIP). RSIP will implement an ASME B PV Code Section XI based ISI program after restart of K Reactor. The establishment of a Code based ISI program at SRS will affect a transition from a standing log which scheduled inspections to a program structured to commercial reactor standards. The SRS standing log for periodic inspection of equipment was initiated in the early 1970's, approximately the same time Section XI ISI programs were initiated at commercial reactors. The information contained in this article was developed during the course of work under Contract Number AC09-89SR18035 with the US Department of Energy

Owen Hedden Overview of the Impact of Ultrasonic Examination Performance Demonstration on the ASME Boiler and Pressure Vessel Code

This paper addresses implementation of ultrasonic (UT) process qualification by performance demonstration as imposed by the ASME Boiler and Pressure Vessel Code Section XI, Appendix VIII. The intended audience for the present paper is an engineer with a good knowledge of NDE, but a limited knowledge of the ASME Codes and Standards. The starting point for application of UT performance demonstration is described in a paper published in this journal just over a decade ago by Cowfer and Hedden. That paper addressed the application of ultrasonic performance demonstration to qualify an examination process for ASME Code Section XI inservice inspection. The present paper provides a brief summary of papers specifically selected to provide the reader with a concise update of progress in UT performance demonstration since the earlier paper. Given that qualification, the reader should not expect new information in this present paper. The papers selected have been mostly selected from those presented at ASME Pressure Vessels and Piping Conferences, from 1995 to 2002, addressing the subsequent development and application of the UT performance demonstration process. The emphasis is on work performed for nuclear utilities under the Performance Demonstration Initiative (PDI), for application to Section XI inservice inspection. However, material also is included describing parallel work in the European Community, and applications of UT performance demonstration in Sections I and VIII of the ASME Boiler and Pressure Vessel Introduction This paper attempts to provide an overview of the newer requirements for ultrasonic ͑UT͒ performance demonstration in the ASME Boiler and Pressure Vessel ͑BPV͒ Code Section XI Appendix VIII ͓1͔. Section XI is ''Rules for Inservice Inspection of Nuclear Power Plant Components;'' its Appendix VIII is mandatory requirements for ''Performance Demonstration for Ultrasonic Systems. '' To fit this into the context of ASME activities, a little additional information may be helpful. The Council on Codes and Standards is one of several Councils comprising the American Society of Mechanical Engineers. The Boiler and Pressure Vessel Committee is one of many codes and standards committees reporting to the Council on Codes and Standards. All these committees consist of engineers who volunteer their time, usually with the support of their employer, to develop a broad spectrum of nationally ͑glo-bally͒ recognized codes and standards. The Boiler and Pressure Vessel Committee is one of the largest such groups. Upwards of 500 engineers participate in the activities of the Committee and its Subcommittees, Subgroups, and Working Groups. Quoting from its Foreword, ''The Committee's function is to establish rules of safety governing the design, fabrication, and inspection of boilers and pressure vessels, and to interpret these rules when questions arise regarding their intent.'' Code Cases are the vehicle used by the BPV Committee to introduce new materials, new technology, and to provide conditions for acceptance of alternatives to the provisions of the Code. The meetings are open to all interested persons, and anyone may request revisions, new rules, Code Cases, or interpretations for consideration by the Committee upon submittal in writing ͑with full particulars͒ to the Secretary ͑ASME staff͒. Copies of the BPV Code books and Code Cases may be obtained from ASME, and may be found in many engineering libraries in universities and in companies engaged in BPV Code work. Ultrasonic examination is the primary nondestructive examination method required by Section XI for inservice inspection of the welds in major components in nuclear power plants. In 1989 Appendix VIII established a radical new process for qualification for UT equipment, personnel, and procedures. The starting point for application of UT performance demonstration is described in a paper published in this journal just over a decade ago by Cowfer and Hedden ͓2͔. Subsequently, there have been many papers exploring in considerable detail the various implications of these new requirements. This paper will provide an update primarily by reviewing a selection of papers addressing this subject. It will do this by: 1͒ providing a reference to the paper; 2͒ providing a complete copy of the original abstract of the paper, if it has one, or its original introduction; and 3͒ providing a brief review, or commentary, describing the content of the paper. This is intended to give the readers enough information to determine if they want to seek out the paper for further study. The papers are presented in chronological order. Further application within ASME Codes and Standards is also addressed. The emphasis has been on use of UT in place of radiography ͑RT͒. Starting in Section VIII ͑Construction of Pressure Vessels͒, performance demonstration has been the basis for acceptance of UT in lieu of RT for new construction. The current example is Code Case 2235-3 for ͑non-nuclear͒ ASME Code Sections I ͑Construction of Power Boilers͒ and VIII. Õ Vol. 124, AUGUST 2002 Copyright © 2002 by ASME Transactions of the ASME Bibliography "in Chronological Order… Cowfer and Hedden †2 ‡ Abstract. ''Nondestructive examination ͑NDE͒ in Section XI of the ASME Boiler and Pressure Vessel Code has been an evolving process. The Code's use of NDE for inservice inspection ͑ISI͒ to establish fitness for duty has brought major changes in applied NDE philosophy and practice. The publication in Section XI, 1989 Addenda, of mandatory Appendix VIII, ''Performance Demonstration for Ultrasonic Examination System,'' sets a precedent for both NDE performance and recognition of the total NDE system ͑personnel, equipment, and procedures͒. This paper highlights appropriate portions of Appendix VIII. Performance values such as probability of detection ͑POD͒ and flaw sizing are addressed. The use of flawed specimens for performance demonstration qualifies personnel, equipment and procedures, hence the ''Ultrasonic System'' qualification. Appendix VIII provides the opportunity for technique performance demonstration for assessment of material aging and qualification of components and systems for continued service. This article provides the background and justification for Code action to publish Appendix VIII.'' Comment. This paper introduced the application of performance demonstration to ASME Code NDE qualification requirements. The paper concludes with the statements: ''Appendix VIII documents the UT procedure capability and its limitations. When fully implemented, it also will 1͒ allow adjustments to acceptance standards, 2͒ establish NDE as a viable input to probabilistic risk assessment of flaws for continued service, and 3͒ provide quantitative reliability assessment for pending plant operating license renewal actions.'' Together with the concurrent development of risk-based inspection technology, those developments have actually taken place. Implementation of Appendix VIII has been a condition in permitting reduction in Section XI examination volume, and in some cases elimination of further examinations ͑Subarticle IWB-2500 Tables͒, rather than adjustment of the actual examination acceptance standards ͑Subarticle IWB-3500͒. Implementation of Appendix VIII has also been a condition of acceptance of Code Cases N-560, N-577, and N-578, applying probabilistic risk assessment ͑PRA͒ for risk-informed inservice inspection programs, and in plant operating license renewals. ASME PVP-Vol. 317 †3 ‡ Comment. This volume comprises a series of 12 papers under three general headings: In the first set, the paper ''Performance Demonstration in the USA,'' by Spanner et al., provides a good introduction to the utilities' Performance Demonstration Initiative ͑PDI͒, describing development of the library of flawed specimens for use in the qualification program, including statistics on test scores for manual exams of flawed piping welds. In a subsequent paper, Ashwin et al. ͓4͔, give a more comprehensive description of the PDI program and its initial ''lessons learned.'' The first set also includes three reports on work in Europe, two addressing the framework for inspection qualification through performance demonstration and other processes. The proposed process includes consideration of procedures, equipment, and personnel, starting with ''test piece trials using deliberately defective test pieces.'' The remaining paper gives results of blind tests on flawed steam generator tube specimens by 17 teams using several NDE methods. One of the remaining sets of papers addresses effectiveness of inspection procedures for cast and wrought austenitic welds. The other addresses procedures and performance demonstration for wrought austenitic welds and ferritic pipe. The papers report mostly on various projects in the European Community roundrobin Program for Inspection of Steel Components ͑PISC III͒. These show the variability in the examination results of the participating NDE teams, the problems associated with developing natural and artificial flaws into the test specimens, the differences in techniques employed to detect and to size flaws, and need to balance correct detection, correct rejection and false calls. They also help identify successful and unsuccessful UT techniques. All of these provide background for developing performance demonstration requirements. This is an excellent tutorial volume and could be cited in much greater detail here. Ashwin et al. †4 ‡ Abstract (Excerpt). ''To provide the U.S. nuclear industry with a uniform implementation of the Performance Demonstration requirements within the 1989 addenda of ASME Section XI, Appendix VIII, representatives from all US nuclear utilities formed the Performance Demonstration Initiative ͑PDI͒. The PDI recognized the potential benefits that Appendix VIII offered the nuclear industry and initiated a proactive approach to implement the requirements. In doing so it was expected that performance demonstration of ultrasonic examination procedures would allow for improvement in the efficiency and credibility of inservice inspection to be realized.'' Comment. The examples given in the paper clearly show what it has taken to convert Appendix VIII's principles to practice. 1. The need to apply tolerances to specimen configuration requirements, to minimize the size of specimen sets, quickly became evident. For instance, a pressurized water reactor ͑PWR͒ nozzle inner radius examination ͑typically conducted from the inside surface͒ might be accomplished with a single specimen, while the same examination on a boiling water reactor ͑BWR͒ ͑typically conducted from the outside surface͒ might require as many as five. 2. Meeting the specimen material requirements proved to be a particular stumbling block for bolting specimens. Utilities were unwilling to offer spares, because they were in chronic short supply, and easily available standard bolting seldom met the rigorous nuclear quality assurance requirements. Less exacting documentation requirements were proven to be sufficient for bolting specimens. 3. The Appendix VIII principle that actual flaws be used in all qualification specimens challenged flaw manufacturing technology. A compromise was reached permitting electrodischarge machined ͑EDM͒ notches in specimens for small bore nozzles. 4. The test requirements for individual personnel performance demonstrations, when combined, require a formidable number of specimens. Review within PDI justified optimizing the combined examinations, reducing the number of specimens. 5. Need for additional guidance on the use of the acceptance criteria was determined. Appendix VIII flaw tolerance requirements have subsequently been modified, as indicated in some of the other papers discussed herein. Walker and Ammirato †5 ‡ Abstract. ''Risk-informed inservice inspection ͑RISI͒ programs effectively concentrate limited and costly examination resources on systems and locations most relevant to plant safety. The thought process used in the selection of nondestructive evaluation ͑NDE͒ methods and procedures in a RISI program is expected to change toward integrating NDE into integrity manage- Journal of Pressure Vessel Technology AUGUST Comment. With the principle established by performance demonstration based UT rather than ''one-size-fits-all'' basic UT procedures, the door was opened for introduction of the concept of procedures qualified to identify specific damage mechanisms. While never adopted by Section XI, the procedures developed by the EPRI NDE Center to detect and size IGSCC were the precursors to the PDI program. This paper describes the application of procedures qualified to identify specific damage mechanisms into risk-informed inservice inspection programs being introduced in nuclear power plants. It covers the whole catalog of damage mechanisms encountered in the primary systems of operating nuclear power plants, and provides recommendations addressing the examination of each. Walker †6 ‡ Abstract. ''Risk-informed inservice inspection ͑RISI͒ programs are currently being designed to effectively concentrate the limited and costly examination resources on systems and locations most relevant to plant safety and operation. Current RISI programs are concentrating on applying RISI principles to plant piping systems as plant owners will reap the greatest benefits from RISI on their piping systems, as compared to other components within the plant. The thought process used in the selection of nondestructive evaluation ͑NDE͒ methods and procedures in a RISI program is changing towards integrating NDE into an integrity management program, with a concentration on understanding failure mechanisms and their relationships to specific NDE methods. Identifying which damage mechanisms may be operative in specific locations and applying the appropriate NDE methods to detect the presence of these damage mechanisms is fundamental to application of an effective RISI plan. Considerable information is already available on inspection for damage mechanisms such as intergranular stress corrosion cracking ͑IGSCC͒, creep cracking, thermal and mechanical fatigue, and flow accelerated corrosion ͑or erosion-corrosion͒. Similar procedures are under development for other damage mechanisms that may occur individually or in combination. Guidance is provided on qualification and application of NDE procedures in a RISI framework to facilitate implementation by plant staff or contractors. With the RISI process, examiners focus on the specific examination location and, with the knowledge of which damage mechanism could ͑and is expected to͒ occur there, perform the appropriate NDE such that the damage mechanism may be detected and identified. Performing NDE techniques inappropriate for the anticipated damage mechanism does not add to the detection probability and is discouraged due to the unnecessary expense associated with the examination. As such, examiners should be made aware of the characteristics of each damage mechanism and its relationship with the NDE methods being implemented in order to perform an effective examination.'' Comment. This paper is essentially an update of the paper by Walker and Ammirato ͓5͔ discussed previously. It provides further information on techniques found successful in detection and sizing of several of the listed damage mechanisms: Thermal fatigue, chloride corrosion cracking, crevice corrosion cracking, primary water stress corrosion cracking, intergranular stress corrosion cracking, microbiologically influenced corrosion, erosioncavitation, and flow-accelerated corrosion. Goto et al. †7 ‡ Abstract. ''Prior to application of automated ultrasonic examination by TOFD for welds according to ASME Code Case 2235 ͑1997͒, the following items should be considered: ͑1͒ Performance demonstration of TOFD technique for planar type flaws referenced in the acceptance criteria ͑Max. 0.06t reference flaw size tϭtest block thickness͒. ͑2͒ Scanning method for detection of transverse flaws. ͑3͒ Shape of embedded flaws in a qualification block. ͑4͒ Others ͑Basic examination conditions/parameter, etc.͒. Several experiments of UT technique performance demonstrations were conducted in accordance with Case 2235 using test blocks with embedded planar-type flaws. The performance demonstrations confirmed that The Japan Steel Works ͑JSW͒ procedure fully satisfies Code Case 2235. This paper describes JSW TOFD ultrasonic technique performance test results in lieu of radiographic examination using test blocks with embedded artificial planar type flaws sized according to the acceptance criteria of Code Case 2235.'' Comment. Anyone considering application of Code Case 2235 for the first time would do well to be guided by the experience described in this paper. There is an unusually high degree of technical details and technique revealed here. The paper includes a number of tables presenting data on UT probe performance, illustrating how some of the successful examination procedure parameters were determined. It is evident from this paper that application of the Case, and the principles of performance demonstration, is not simply a matter of taking a procedure off the shelf. Careful preparation is a significant factor in success. Rana et al. †8 ‡ Abstract. ''In 1996, Code Case 2235, which allows ultrasonic examination of welds in lieu of radiography for ASME Section VIII Division 1 and Division 2 vessels, was approved by the ASME B&PV Code Committee. This Code Case has been revised to incorporate: ͑1͒ a reduction in minimum thickness from 4Љ ͑107.6 mm͒ to 0.5Љ ͑12.7 mm͒ and ͑2͒ flaw acceptance criteria including rules on multiple flaws. A linear elastic fracture mechanics procedure has been used in developing the flaw acceptance criteria. This paper presents the technical basis for Code Case 2235.'' Comment. In addition to providing a technical basis for Code Case 2235, this paper explains the need for specific UT acceptance standards to accompany the UT performance demonstration. For the reliable and reproducible UT examination to be economically practical, it needs to be applied in conjunction with appropriate UT acceptance standards. Whether for inservice inspection or for new construction, this principle holds. The paper provides extensive references to support its contention that Code Section V UT does provide the reliability to allow its use for acceptance of welds for new construction. It provides a description of the adaptation of the Section XI Appendix VIII performance demonstration process to ''new construction'' vessel welds. It also provides the basis for insistence that UT examination acceptance criteria distinctly different from RT workmanship acceptance criteria are necessary, and describes in detail the development of those standards. The Code Case is presently being updated based on continued feedback from field applications. Õ Vol. 124, AUGUST 2002 Transactions of the ASME Comment. The previous paper by these authors, Goto et al. ͓7͔, concentrated on development of the UT procedure in accordance with Code Case 2235. This paper discusses several related aspects of application of the case, as noted in the abstract above. In the economic example, the time for UT of the vessel was about 60% of the time for RT. RT included time for transport to the RT facility, always a logistic problem in a fabrication shop. Then, if flaw indications are found, the disparity becomes greater because of the unknown depth in the weld of the flaw, requiring a larger excavation, and the need to repeat the transport to the RT facility. The other examples verify the ability of TOFD UT to detect and characterize weld flaws, particularly in comparison to RT. This demonstrates the usefulness of TOFD UT in defining weld flaws in new construction as well as service-induced flaws. Modes †10 ‡ Abstract. ''The Code of Federal Regulations Title 10 Part 50 'Industry Codes and Standards' was amended on September 22, 1999. Applying the rule a NRC licensee may implement an alternate to the American Society of Mechanical Engineers ͑ASME͒ Boiler and Pressure Vessel Code, Section XI, Appendix VIII, 1995 Edition with 1996 addenda. The rule does not mandate the alternate. The rule does require an expedited implementation of ASME Section XI Appendix VIII as written or as excepted by the rule. The rule was structured along four general guidelines. The rule was written to take exception to the use of notches in performance demonstrations, to allow the Performance Demonstration Initiative implementation to continue with a minimum impact on individuals previously qualified, to include flaws produced at up to 45 degrees off axis due to undocumented repairs, and to establish dates when the supplements to Appendix VIII would be required. The NRC agreed to address the reactor vessel's reduced sensitivity to notches and imbedded flaws in the outer portion of the vessel wall. For that reason a more relaxed requirement in the outer 85% of the vessel wall was traded for a more vigorous inspection of the inner 15%. This paper will discuss regulatory perspectives on this rule including NRC stipulated limitations on the use of single-sided examinations and clarifications on NRC's intent to single sided examinations.'' Comment. It must be recognized that NRC always has the last word regarding