ML19343D182
| ML19343D182 | |
| Person / Time | |
|---|---|
| Issue date: | 03/11/1981 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-1814, NUDOCS 8104090829 | |
| Download: ML19343D182 (17) | |
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MINUTES OF THE A RS SUBCOMNITTEE MEETING ON METAL COMPONENTS (INSERVICE INSPECTION)
WASHINGTON, DC JANUARY 7, 1981 A meeting of the ACRS Subcommittee on Metal Components was held in Room 1167, 1717 H St., NW, Washington, DC, on January 7,1981. The purpose of the meet-ing was to review with the NRC Staff and industry current ultrasonic test (UT) procedures and methods of inservice inspection (ISI) for reactor coolant pressure boundary components.
There were no oral Copies of the, schedule and attendea list are attached.
presentations nor written statements received from members of the public.
The entire meeting was held in open session. Handouts distributed at tha The meeting was meeting are attached to the Office Copy of the minutes.
convened at 8:30 a.m. and the opening statement was presented by Dr. P. G.
Shewmon, Chainnan of the Subcommittee.
S. Pawlicki, NRR, introduced the NRR participants and noted that R. McClung, ORNL, and J. Gieske, Sandia National Laboratory, are consultants to the NRC on the matter of UT during inservice inspection.
M. Bender asked the Staff to discuss its current views cnd scenarios about mechanisms that could cause propagation of a postulattd crack in the pressure vessel or piping.
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1/7/81 W. Hazelton "esented an overview, philosophy, and roles of NRR, 050, I&E, and RES in the matter of ISI.
He also briefly discussed the Staff's requirements and criteria in this matter.
The ISI program is based on the requirements of the ASME,Section XI Code.
The NRC erMorses the ASME Code and its requirements but this does not mean that the NRC is completely satisfied with it. The Staff agrees with the acceptance criteria of the Code but believes that the UT inspection methods are not adequate to es-tablish that the acceptance criteria are met.Section XI of the Code covers only welds and metal in the immediate vicinity of the welds.
The material between welds is inspected to other standards before fabrication.
The Subcommittee discussed with the Staff the current technical bases for the continued operation of reactor pressure vessels in light of current licensing requirements.
Mr. H. Etherington suggested that a formal review of the Marshall Report on pressure vessel integrity should be performed by the Staff.
W. Hazelton stated that, theoretically, a one-half inch flaw (more or less) located on the inner surface of the pressure vessel could propagate thror,h the vessel wall during a scenario that includes vessel depressurization, cooldown, and repressurization. Administratively, an operator is prohibited from repressurizing a cold vessel, hence, vessel failure will be prevented.
l METAL COMPONENTS.'.
1/7/81 W. Hazel'.on stated the major concerns regarding 'the ISI program for PWR reactor vessel beltline welds are (1) many welds are inspected only once every 10 years, (2) significant irradiation reduces critical flaw size, and (3) many welds are inspectable only frem the inside' of the vessel.
It was Mr. Mazelton's opinion that the ASME Cod? ctsmination procedures are not adequate to detect and characterize flaws to ASME Code Section XI acceptance criteria.
V. Goel OSD, discussed the proposed regulatory guide on UT of reactor vessel welds during preservice and inservice examination.
Following are highlights of main differences between Section XI and the proposed regulatory guide.
The guide will. require:
More frequent instrument checks.
That the material near the pressure vessel inner surface that is not adequately examined due to near-field effects or electronic gating should be identified and recorded.
The Code requires that weld areas be examined by 45 and 60 degree UT angle beams.
These angles are not always ef fective.
The guide recommends a beam which is within 15 degrees of the perpendicular to the weld / metal interf ace.
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METAL COMPONENTS 4-1/7/81 J. Collins, I&E, discussed the involvement of I&E in the ISI program. He discussed the plants that are undergoing the 10-year ISI program. About 12 plants are undergoing the ISI program and about 5 plants have completed their inspections and I&E has reviewed the results.
It has been suggested that membcrs of the Subcommittee would benefit from being present when an ISI is in progress. The Subcommittee concurred.
A. Curtis, Rochester Gas & Electric (Ginna), discussed their 10-year ISI program and results.
The Ginna plant, a 2-loop, Westinghouse-built PWR, was not designed to be inspected to requirements of the current Section XI Code.
Some of the problems encountered during the ISI program are as follows:
Calibration blocks of the same or closely similar material were difficult to obtain.
Piping and component insulation were dif11 cult to remove prior to inspection. More radiaticn exposure was obtained during insulation removal and reassembly than during ISI.
Many pipe runs and components were not designed to be accessible for ISI.
Sone weld joints are not designed to be UT.
In this case, radiographic examination was used.
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1/7/81 A. Curtis discussed the results of the inspection and ino: ated that some unacceptable flaws we e found and corrected.
The results of the inspection are recorded on a computer.
Statistical analysis of Ginna's data and of other plant inspection results may be collated and analyzed by the INP0 - Nondestructive Examination Center in Atlanta, Georgia.
A. Whiting, Southwest Research Institute, discussed current ISI techniques.
The Section XI Code was essentially designed to detect low cycle fatigue cracks.
This type of crack can be found quite readily because the crack surfaces are distinctly separated.
Stress corrosion cracking, on the other hand, is very difficult to detect because it is a very tight crack. More stress corrosion cracking than fatigue cracks are found in current plants.
Cracks in or under the cladding of pressure vessels cannot be found using the tecnniques delineated in the Code.
Mr. Whiting indicated that U.S. industry does not seem to be interested in cracks in or under the cladding.
In fact, in the area of cladding to base metal bond, inspection is not effective because of the large amount of background noise.
Because of the ambiguity of signals from this area, they are electronically " blanked-out" for the first inch or so from the inside surface of the pressure vessel.
Cracks in this area are probably the most significant in the propagation of cracks through the pressure vessel wall, In some foreign countries, the cracks in the cladding'to base metal bond region are detected and characterized by using the twin crystal UT technique, which is a significart improvement over present USA techniques.
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1 METAL COMP 0NENTS.
1/7/81 A. Whiting also dis.ussed how reliability and reproductibility in the exami-nation process could be improved. This is done by:
(1) a more specific definiton and better selection of nondestructive examination techniques, (2) the need for trained and qualified operators and better instrumentation, and (3) the technical expert evaluating a reactor vessel for further service must be qualified by experience and training as well as by having the addi-tional complementary information from supplemental NDE techniques.
There is a current effort to take the human element out of the examination process for the following reasons:
To have a more uniform level of performance by all examiners and examinati'on agencies.
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- Minimize radiatior exposure to personnel.
Overcome the sho/tage of experienced examiners and analyzers.
L. BecKer, Pacific Northwest Laboratory, discussed a program of integrating NDE reliability and fracture mechanics.
This project is sponsored by NRC-RES.
The scope of the program is:
To perform inservice inspection of primary system piping with service-induced cracks.
- To monitor and evaluate the results and progress of Pressure Vessel Research Council, Japan Pressure Vessel Research Council, Plate Inspection Steering Committee, and UK validation programs.
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METAL COMPONENTS,-
1/7/81 The objectives of the program are to:
Determine the reliability of UT-ISI.
Use fracture mechanics analyses to detenaine the impact of NDE unreliability on safety.
Evaluate the degree of reliability improvement which could be achieved using improved and advanced NDE techniques.
Fonaulate recommended revisions to the Code based on material, service, and NDE uncertainties Some results and conclusions of the program thus far are:
Section XI provides no assurance that an unacceptable flaw will be found and reported.
Acceptance of the latest revision of Section XI has 3sulted in a loss of inspection sensitivity.
The program also includes a "round robin" series of examination by about six or seven groups in the USA. Materials with induced flaws have been fabricated with typical weld sizes and materials as found in plants today.
Testing is scheduled to begin in February 1981.
A. Mucciardi, Adaptronics, discussed the status of an automatic UT pipe inspection system. This work is sponsored by EPRI. The system uses existing sensors to detect flaws and through a signal processing computer enhance and 7
METAL COMPONENTS 8-1/7/81 characterize the sensor output.
The size of the equipment that processes the signals is about the size of a small suitcase.
The unit has been built and will be evaluated in 1981. This equipment will probably be used in the round robin test program.
The Subcommittee plans to further explore the matter of ISI for reactor coolant pressure btundary components in subsequent, meetings.
The meeting was adjourned at 4:40 p.m.
NOTE:
For additional details, a complete transcript of the meeting is avail-able in the NRC Public Document Room,1717 H St., NW, Washington, DC 20555 or from Alderson Reporters, 300 7th St., SW, Washington, DC, (202)554-2345).
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- Application of Dil-2 Lessons he agenda for embiect meeting shall Janu:ry 29-30.1981. los Angel;s. C5.
Le:rned m Near Tzim Consfivetion be as fo!Jows:
ne Subcommittee wiH discuse thi Permit Reacton-propoud NRC y,ed adg.*Mvery E mfg 2 at:tus of the Selscue Sclety Margins rulemaking.
untilthe conclusion of business C. *Rehability of NucintPowerPlant Program. Notice of this meeting wse Scmm Systems-provisions for review DuringtheinitialporGonof the pubbshed Nov. 25 of safety systems.
meettng. the Subcommittee. along witl~
- ladion Point 2/Meer/ Components.
D. 'NRC Safety Research Pmgrom-any of its consultants who may be Rescheduled from January to February Annual ACRS pepcrt to the U.S.
present, will exchange preliminary 1981 (date to be announced).
Washington.DC.De Subco.nmittee will Congress and reentuation of the IDFT he npr6ng muen k be considered during the balance of the Progr,am.E. Cenericite ns Applicable tol.ig%
avi;w the possibN pressure verse!
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F. ControlSystem Fouures which peesentations by and bold discuestena a[tpeton. DC.%e Affect Flort Safety-4teus for ACRS with representatives of the NRC Staff, 7,
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their consultanta, and other interested j
m considerstion, I
will di d
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- Anticipated honsients Without penons regardmg this revicw.
R a ry uides and R taos s.
Scmm--clardcation d ACRS nport to Further Information regering epica h
l tion of this meeting was published NRC. dated May 11,1980.
to be d4cuated.whether the meeting H' 'L'#"I*'#'Y AI'I'5"~'"* **0 ba* b*e3 cancelled or teschedu1ed the revist ne to NRC Regulatory Gul{es and Chairman's ruling on requesta for the
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' Tentative).Weshington.DC.He lubcommittee will begin the review of
- h,,"tfng with NRC Commissioners #ppatunhy W pnwnt wal statemata i
and &e Eme aHoued emfw can b ene South Carolina Electric and Ces and becutive Directorfor Opemtions-- obtained by a prepaid telephone call to Company's application to e an Operating discuse NRC Staff activities and ee cgnizant Designated Federal Uc:nse for the Summer P! ant in the ares Commission naction to ACRS reperta.
Employee. Mr. F. Igne (telephone 202/
of seismic issues.
'NRCSofety Researcl. Pmgmm.
Febivory5-7 'seI Agenda to be e34-14*.). between 4:15 a.m. and 5:00 F;bruary 4.1981 (Tents cive),
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p.m., e.a.t.
announced.
W ashington. DC. %e subcommittee will March 12-14.1961: Agenda to be Dated. Deceuber 17,1sso.
discuss the draft AC"AS Report to announced.
Mn C Hope.
Congress on NRC's FY 198:Reaetor Deted. December 15. teso.
Adrisory Coaunistee Manerement Ofhoer.
Safsty Re.earch Programs and Budget.
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N:tice of this meeting was published Advisory Coaunittee Management Officer.
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' ' Transportation ofRadioactive aussa cooe rem *es Materials,l. ate February,1981.
Reactor Safeguarts Advisory Wcshington. DC.ne Subcommittee will Committee; Regula'ory Activit6es begin a review of the transportation 8
Subcommittee; Meetmg certification process of the NRC Cm t
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De ACRS Subcommittee on Transportation Certification Branch.
Subcomtr4ttee; Weeting Regulatory Activicities will hold a ne ACRS Subcommittee on Metal muting on Jamary 6. st in Room _
(d e to e a oun ed) nea Columbia. SC).The Subcommittce wiH Components will hold a meeting at 8:30 1048.1717 H Street. N.W., Washington.
a.m. on January 7,1981 in Room 1187, continue review of the Operatmg 1717 H Street. N.W., Wa shington. DC to DC. Notice of,this meeting was E
Ucense application.
&scuss the Intervice Inspection Program Published November 25.1980.
- Ceneric Items. March it.1981.
ic Reactor Pressure Vessels and Piping.
In accordance with the procedurees-Washington.DC.ne Subcommittee wiH riotice of this meeting was published outlined in the Federal Register on
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review NRC Staff Action Plans and th,g October 7,1980. (45 FR 66535) oral or November 25.1980.
responsiveness to ACRS concerns in accordance with the procedures written statements may be presented by
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outlined in the Federal Register on members of the public, recordings will M1rch.1981 (date to be annowced).
October 7,1980 (45 FR 66535), oral or be permitted only during those portions Wcshington, DC. He Sube anf ttee will written statements may be presented by of the meeting when a transcript is being continue ACRS review of TMI-1 restart.
members of the public, recordmgs will kept, and questions may be asked only
- Three MUe Island. Unit 2. Recovery, be permitted only during those portions by members of the Subcommittee.its March.1981(date to be announced),
of the meeting when,a transcri tis being consultants, and Staff. Persons desiring Wcshington. DC. The Subcommittee will kept, and questions may be as ed only to make oral statements should notify review the progress and plans for the 0"
the Designated Federal Employee as far,
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TM1-2 recovery e!Iort and discuss j
d in advance '8 practicable so that interaction with the nG-2 Advisory to make oral statements should notify appi priate arrangements can be made the Designated Federal Employee as far to sHow the necessary time during the Panel.
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ACRS Fun Committee Meetings in advance as practicable so that meeting for such statements.
appropriate arrangements can be made The entire meeting wiH be open to
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to allow the necessary time during the
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l A. 'Sequoyoh Nuclear Plant-meeting for such statements.
De agenda for subject meeting shall provisions for control of combustible ne entire meeting will be open to l
3'.sses following a naclear accident.
public attendance.
be as foUows:
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TENTATIVE SCHEDULE ACRS SUBCOMMITTEE HEETING ON METAL COMPONENTS INSERVICE INSPECTION WASHINGTON, DC JANUARY 7, 1931 PURPOSE _:
To review with the NRC Staff and industry current procedures and method-ologies of inservice inspection, U.T., on reactor coolant pressure boundary components, for example, pressure vessel and piping.
APPROXIMATE TIE 8:30 a - 8:45 a I.
CHAIRMAN'S OPENING STATEMENT II. PRESENTATION BY THE EC STAFF 8:45 a - 9:00 a 1.
Introductory Statement (Noonan) 9:00 a - 10:15 a 2.
ER Presentation (Hazelton)
Overview, philosophy, roles of NRR, OSD, I&E, and RES Staff requirements and criteria,Section XI, others O General 0 Reactor Vessel O Major Concerns O Code Adequacy 10:15 a - 11:00 a 3.
18E Activities (Collins)
Review of detailed programs
- Monitoring inspections 11:00 a - 11:15 a
- BREAK Reporting, evaluation, NRR interface 11:15 a - 11:50 a 4.
Standards Activities (Goel)
- Weaknesses in Code UT procedures for ISI of vessels Requirements of Re.gulatory Guide " Ultrasonic Testing of Reactor Vessel Welds During Preservice and Inservice. Examination";
Status of Guide y
.. R; vised 1/6/80 METAL COMPONENTS (1/7/ 80 APPROXIMATE TIME _
5.
Sunnary of Staff Criteria, Cocerns, and 11:50 a - 12:15 p Activitires 12:15 p - 1:15 p
- * * * * * * * * * * * * * * * * * * * *
- LUNCH III. PRESENTATION BY INDUSTRY 1.
Ginna (PWR) on 10-year Inspection Program 1:15 p - 1:45 p and results.
2.
Southwest Research (Alan Whiting)
Current ISI methods, current alternative methods, and reliability of detecting and characterizing weld and r.aterial defects and cracks due to 1:45 p - 2:15 p stress corrosion and fatigue.
2:15 p - 2:45 p Pacific Northwest Laboratory (Becker) 3.
Discussion of U.T. program. Program objectives, and schedule.
2:45 p - 3:00 p
- BREAK 3:00 p - 3:30 p 4.
Adaptronics (Mucciardi)
Status of its research project on U.T. signal analysis.
3:30 p - 4:00 p IV.
SUBCOMMITTEE CAUCUS 4:00 p - 4:15 p DISCUSSION WITH PARTICIPANTS AND ADJOURNMENT V.
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