View source for HL-5728, Requests That RPV Shell Weld Ultrasonic Exams Be Performed Using Techniques & Procedures,Iaw ASME Section Xi,App Viii, 1992 Edition,1993 Addendum,In Lieu of ASME Section XI,1989 Edition Exam Techniques & Procedures

{{Adams
| number = ML20199K145
| issue date = 01/19/1999
| title = Requests That RPV Shell Weld Ultrasonic Exams Be Performed Using Techniques & Procedures,Iaw ASME Section Xi,App Viii, 1992 Edition,1993 Addendum,In Lieu of ASME Section XI,1989 Edition Exam Techniques & Procedures
| author name = Sumner H
| author affiliation = SOUTHERN NUCLEAR OPERATING CO.
| addressee name = 
| addressee affiliation = NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
| docket = 05000321
| license number = 
| contact person = 
| document report number = GL-98-05, GL-98-5, HL-5728, NUDOCS 9901260343
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE
| page count = 14
}}

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Lewis Sumner                Southern pieclear
     .                  Vice Presideat              Operating Company,Inc.
Hatch Project Suppet        40 invemess Parkway
                   .                                Post Office Box 1295 Birmingham. Alabama 35201 i
Tel 205.992.7279                                                                                                  I Fax 205.992.0341 l
soumanm                                                         ;
COMPANY                                           '
January 19, 1999                                                         Energy so Serve kr%rld" Docket No. 50-321                                                                           HL-5728 U.S. Nuclear Regulatory Commission ATTN: Document Con +.rol Desk Washington, D. C. 20555 Edwin 1. Hatch Nuclear Plant - Unit 1 RPV Shell Weld Examination Ladies and Gentlemen:
On December 2,1998, Southem Nuclear Operating Company (SNC) submitted a proposed                                                       ;
alternative for the RPV shell weld examination requirements contained in 10 CFR                                                     4 15 50.55a(g)(6)(ii)(A)(2). This alternative proposed use of the report "BWR Vessel and Internals                                          :
Project, BWR Reactor Pressure Vessel Shell WeH Inspection Recommendations (BWRVIP-05)"
h per the guidance of NRC Generic Letter (GL) 98-05 that allows the examination of RPV axial                                                 l welds only. Subsequent review of 10 CFR 50.55a(gX6)(ii)(A) examination requirements resulted                                        [
in a decision for SNC to submit two additional alternatives, one relative to the examination                                        f techniques, and the other relative to the axial weld examination coverage.
                         'Ihe Edwin I. Hatch Nuclear Plant (HNP) Unit i Reactor Pressure Vessel (RPV) shell welds are scheduled for examination in the Spring 1999 Maintenance / Refueling Outage. Per 10 CFR                                             h 50.55a(g)(6)(ii)(A)(2), the RPV shell weld examinations for Plant Hatch are to be performed in                                    !
accordance with the requirements of ASME Section XI,1989 Edition. Table IWB-2500-1, Examination Category B-A requires a volumetric examination of essentially 100% of all RPV shell welds. Essentially 100%, as used in Table IWB-2500-1, means more than 90% of the examination                                                   l volume of each weld where the reduction in coverage is due to interference by another component                                             1 or pan geometry. Anicle IWA-2000, paragraph IWA-2232, then references Mandatory                                                               j Appendix I for the performance of ultrasonic examination. Appendix I states that " Ultrasonic examination of vessel welds greater than 2 in. thickness shall be conducted in accordance with                                           h Article 4 of ASME Section V, as supplemented by this Appendix."                                                                             ,
During the Fall 1997 Maintenance / Refueling Outage, areas ofHNP Unit 1 RPV welds that were                                             I 2 G 0 05,7 accessible from the outside surface were examined using the requirements of the 1989 Edition of M the ASME Section XI Code. The HNP Unit 1 RPV has limited access from the outside diameter for performance of ultrasonic examination. This limitation has resulted in the need to perform                              l /,           f h
additional automated examination from the inside diameter. Also, it is not possible to obtain volumetric examination coverage of 100% of all RPV axial welds from the inside of the vessel due                                    @         '
to interference with various internals components (e g., steam dryer guide rod, surveillance                                         I Ok specimen brackets, jet-pump diffusers, etc.). Detailed examination interference information is contained in Enclosure 1 along with SNC's best estimate of the examination coverage for each RPV axial weld. Enclosure I shows that of the twelve RPV axial welds, five will receive a total examination coverage of essentially 100%, and the average percent total coverage of the twelve
                                                                                                                                                         'd5 RPV axial welds is approximately 76%. The total percent examination coverage represents the                                                 (
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U.S. Nuclear Regulatory Commission Page 2 January 19, 1999 combined examinations from the outside and inside surfaces of the RPV. SNC will provide additional NRC notification if any actual examinanon coverage is significantly different from these estimates.
Based on the information contained in Enclosure 1, these examinations provide reasonable assurance that unacceptable senice-induced flaws have not developed in these welds and that the RPV axial shell weld integrity is maintained. These examinations have or will be performed to the extent practical using state-of-the-art equipment and techniques within the limitations of design and access of the RPV and provide an acceptable level of quality and safety even though all could nct be fully examined. The evaluations and examinations will meet the objectives of the augmented examinations defined in 10 CFR 50.55a(g)(6)(ii)(A), therefore, the proposed alternative should be authorized in accordance with 10 CFR 50.55a(g)(6)(ii)( A)(5).
These examinations from the inside diameter of the RPV will be performed using the General Electric (GE) GERIS 2000 ultrasonic examination system, which incorporates tecimiques and procedures that have been verified in an ultrasonic examination qualification process known as the Performance Demonstration Initiative (PDI). He GE GERIS 2000 ultrasonic examination system does not require strict adherence to many of the explicit requirements found in Mandatory Appendix 1 of the ASME Section XI Code, and Article 4 of ASME Section V, in order to obtain high quality ultrtsonic examination.
A comparison between the ASME Code based methodology and that developed to satisfy the PDI qualification process can best be described as a prescriptive, compliance-based approach (ASME) versus a results-based approach (PDI). The ASME Code uses amplitude-based techniques and procedures in conjunction with a known reflector, which was established independently from the acceptance standards for flaw size found in ASME Section XI. GERIS 2000 utilizes echo-dynamic motion and tip diffraction, which are considered advanced ultrasonic techniques and procedures, and the PDI qualification process which specifies the required results of the examination and validates the acceptable flaw sizes found in ASME Section XI. Also, the PD1           l qualification process confirms performance capability on test samples which incorporate flaws and configurations representative of actual plant conditions. Sensitivity to flaw detection is considered to be greater, and flaw sizing more accurate, than traditional ASME Code amplitude-based techniques and procedures. Also, capability to reliably detect flaws in areas of restricted access increases the effective coverage of the required examination volume when compared to traditional ultrasonic techniques and procedures.                                                                 ,
1 SNC proposes that RPV shell weld ultrasonic examinations be performed using techniques and l
procedures which have successfully completed the PDI qualification process in accordance with l
ASME Section XI, Appendix VIII,1992 Edition,1993 Addendum,in lieu of the ASME Section                 !
XI,1989 Edition examination techniques and procedures. The attached Enclosure 2 is a l         comparison of GERIS 2000 procedures and ASME Section XI Code requirements. The GERIS l         2000 system and personnel successfully completed PDI Qualification Session No. 61-02 at the Electric Power Research Institute (EPRI) NDE Center for both flaw detection and sizing in l
accordance with ASME Section XI, Appendix VIII,1992 Edition,1993 Addenda. The detection and sizing techniques and procedures required to successfully complete the PDI qualification

i     -
t .
l   .                                                                                                    1 U.S. Nuclear Regulatory Commission l       Page 3 i       January 19, 1999 process are considered an attemative method that provides a resultant examination quality higher than those found in the 1989 ASME Section XI Code, even when enhanced with the guidance provided by Regulatory Guide 1.150. Therefore, the PDI qualification process prosides an acceptable level of quality and safety and SNC requests approval of this alternative RPV shell   ;
j       weld examination for HNP, Unit No.1, in accordance with the provisions of 10 CFR                 l 50.55a(g)(6)(ii)(A)(5).                                                                          )
l Should you l ave any questions in this regard, please contact this office.
l Respectfully yours,                                                                              I r          e l
                ?&                                                                                       :
1 H. L. Sun!ner, Jr.
IFUeb Enclosuves:
: 1. RPV Shell Weld Examination Coverage Estimates                                              ,
: 2. Comparison of GERIS 2000 Procedures and ASME Code - Section XI Requirements l
cc: Scutherp Nuclear Operatirn Company                                                           j Mr. P. H. Wells, Nuclear Plant General Manager                                             j SNC Document Management (R-Type A02.001)                                                   )
ILS. Nuclear Reculatory Commission. Washincton. D. C.
Mr. L. N. Olshan, Project Manager - Hatch U. S. Nuclear Reculatory Commission. Recion Il Mr. L. A. Reyes, Regional Adadnistrator Mr. J. T. Munday, Senior Resident inspector - Hatch l
l I
HL-5728 l

Enclosure !
Edwin I. Hatch Nuclear Plant Unit 1 RPV Shell Weld Examination Coverage Estimates The following is a description of the HNP-1 RPV axial welds where estimated examination coverage is less than essentially 100%. The attached summary table provides estimated coverage.
Weld C-2-A                                                                                              .
GE ID Average Code Coverage- 0%
        ;D Limitations -        Steam Dryer Guide Rod at 0 degrees covers weld. No ID scan possible.
OD Limitations -        Restricted due to insulation support ring.
Weld C-3-A GE ID Average Code Coverage- 52.6%
ID Limitations -       (1) Jet pump bracket pads and lower surveillance specirr.en bracket effectively eliminate coverage from EL. 253" to 296.75" (2) The N16A nozzle restricts about 6.5" of coverage at EL. 358" (3) The upper surveillance specimen bracket is located on the weld from EL. 387.5 to 393.5" OD Limitations -        Severely restricted by bioshielding and high levels of radiation. This weld is located in the beltline region and previous surveys have shown that the RPV contact dose rates at the beltline inspection door is 1.5 to 1.7 Rem /hr. The configuration is such that only manual examinations can be performed and lead shielding cannot be effectively used to reduce the radiation levels.
Weld C-3-B GE ID Average Cc,de Coverage- 80.2%
ID Limitations -        (1)                     Jet pump bracket pads effectively eliminate coverage from EL. 288.25" to 296.75" OD Limitations -        Severely restricted by bioshielding and high levels of radiation. This weld is located in the beltline region and previous surveys have shown that the RPV contact dose rates at the beltline inspection door is 1.5 to 1.7 Rem /hr.
The configuration is such that only manual examinations can be performed and lead shielding cannot be effectively used to reduce the radiation levels.
HL-5728                                                            El-1

Encleure 1 RPV Shell Weld Examination Coverage Estimates Weld C-3-C GE ID Average Code Coverage- 80.2%
ID Limitations -          (1)     Jet pump bracket pads effectively eliminate coverage from EL.
288.25" to 296.75" OD Limitations -          Severely restricted by bioshielding and high levels of radiation. This weld is located in the beltline region and previous surveys have shown that the RPV contact dose rates at the beltline inspection door is 1.5 to 1.7 Rem /hr. The configuration is such that only manual examinations can be performed and lead shielding cannot be effectively used to reduce the radiation levels.
Weld C-4-A GE ID Average Code Coverage - 72.1%
ID Limitations -          (1)    Nozzle N2A interferes with several of the scans from EL.172.41 to I84.79 (12.4")
(2) This weld extends below the shroud support plate. The weld below the shroud support plate is not ID examinable. Gussets on top of the support plate further reduce scanning ability. The total limitation is from EL.103"to EL.121.25" OD Limitations -             Severely restricted by bioshielding and high levels of radiation. The top 43" of this weld is located in the beltline region and previous sun eys have shown that the RPV contact dose rates at the beltline inspection door is 1.5 to 1.7 Rem /hr. The configuration is such that only manual examinations can be performed and lead shielding cannot be effectively used to reduce the radiation levels.
Weld C-4-B GE ID Average Code Coverage - 0%
ID Limitations -           (1)    Shroud Repair Restraint at 135 degrees covers a significant portion of the weld and makes ID scan of this portion of the weld impossible.
Repositioning the Shroud Repair Restraint to allow access for GERIS 2000 examination of the weld from the RPV ID, and subsequent                                                                l restoration, would require special equipment and approximately two l
days of refueling floor schedule. While the restraint design provided for a contingency of removal, repositioning or removal were never anticipated after final installation. The upper and lower retainer clip design and function does not anticipate multiple removals and the l
HL-5728                                               El-2

l l   . Enclosure 1 RPV Shell Weld Examination Coverage Estimates                                                     !
l l
possibility of breaking a clip exists whenever one is removed.         l Repositioning the restraint to allow weld examination requires:
l                                . disengage the upper springjacking bolt retainer clips,
{
l l                                     remove upper spring to allow access to mid support assembly, e    install hydraulic jack between RPV shell and shroud repair l
l                                     restraint,
;                                e    using jack, bow the shroud repair restraint allowing disengagement of the retainer clip and then removal of the mid
                                                                                                         )
l                                     support assembly, i
e    remove and reposition hydraulicjack to lower location, e    using jack, again bow the shroud sepair restraint allowing disengagement of the retainer clip and then rotation of the lower contact block, l
l e    disengage lower support retainer clip, e    rotate lower contact block.                                        ,
1 Restoration would be accomplished by performing the above sequence in the reverse order to return the restraint to operational status.
l
)                        (2) The remainder of this weld extends below the shroud support plate.
l                               The weld below the shroud support plate is not ID examinable.
l l     OD Limitations -   Severely restricted by bioshielding and high levels of radiation. The top 43"   l of this weld is located in the beltline region and previous surveys have l
shown that the RPV contact dose rates at the beltline inspection door is 1.5 l                        to 1.7 Rem /hr. The configuration is such that only manual examinations can be performed and lead shiciding cannot be effectively used to reduce the radiation levels.
l l     Weld C-4-C GE ID Average Code Coverage - 72.1%                                                                ,
1 ID Limitations -   (1)    Nozzle N2H interferes with several of the scans from EL.172.41 to 184.79 (12.4")
(2)      This weld extends below the shroud support plate. The weld below the shroud support plate is not ID examinable. Gussets on top of the HL-5728                                        El-3

Encleure1 RPV Shell Weld Examination Coverage Estimates support plate further reduce scanning ability. The total limitation is                            ;
from EL.103" to EL.121.25".                                                                       i OD Limitations -                  Severely restricted by bioshielding and high levels of radiation. The top 43"                              i of this weld is located in the beltline region and previous surveys have shown that the RPV contact dose rates at the beltline inspection door is 1.5 3
to 1.7 Rem /hr. The configuration is such that only manual examinations can be performed and lead shielding cannot be effectively used to reduce the radiation levels.
                                                                                                                  .                                           i 1
HL-5728                                                        El-1

. Enclosure 1 RPV Shell Weld Examination Coverage Estimates Weld Examination Coverage Table ID %               OD %              Total %
Weld        Coverage            Coverage           Coverage                    Remarks C-1-A           NA (1)            99.6% (2)            99.6 %    Examinations complete.
1 C-1-B           NA (1)            90.7% (2)            90.7 %    Examinations complete.
C-1-C           NA (1)            93.3% (2)            93.3 %    Examinations complete.
l C-2-A             0%              77.7% (2)            77.7 %    See C-2-A discussion for details of coverage limitations or other restrictions.
C-2-B          73.Es(3)           75.0% (2)            98.0 %    OD plus ID coverage satisfies minimum coverage requirement.
C-2-C          73.2%(3)           77.2% (2)           100.0 %    OD plus ID coverage satisfies minimum coverage requirement.
C-3-A          52.6%(3)              0%                52.6%     See C-3-A discussion for details of coverage limitations or other restrictions.
C-3-B          80.2%(3)              0%                80.2 %    See C-3-8 discussion for details of coverage limitations or other restrictions.
C-3-C          80.2%(3)              0%                80.2 %    See C-3-C discussion for details of coverage limitations or other restrictions.
C-4-A          72.1%(3)~             0%                72.1 %    See C-4-A discussion for details of coverage limitations or other restrictions.
C-4-B             0%                 0%                 0%       See C-4-B discussion for details of coverage limitations or other restrictions.
C-4-C         72.1%(3)               0%                72.1 %    See C-4-C discussion for details of coverage limitations or other restrictions.
NOTES:
: 1. No examination from ID is required since OD coverage of > 90% satisfies requirements.
: 2. Examinations were performed from the RPV exterior surface during the fall 1997 refueling outage. Percentage reported is the actual coverage achieved.
: 3. Estimated coverage based on access eviluation performed by GE.
HL-5728                                         El-5

_ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ . -                                                                      _ _ _ _ .~._. _
l i
\
l l                                                                                Enclosure 2 i
Comparison of GERIS 2000 Procedures and ASME Code- Section XI Requirements i
This hment compares the General Electric (GE) Performance Demonstration Initiative (PDI) qualified reactor pressure vessel (RPV) examination procedures to ASME Section XI,1989            f Edition and the related requirements of ASME Section V,1989 Edition, Article 4. The GERIS         !
l                                  2000 invessel system was successfully demonstrated in accordance with the PDI-RPV Protocol which implements the requirements of ASME XI, Appendix VIII,1992 Edition with the 1993 i
Addenda.
l                                  ASME Section XI, Division I                                                                       '
i l
l                                  IWA-2230 Volumetric Examination l
l                                  A volumetric examination indicates the presence of discontinuities throughout the volt me of l                                  material and may be conducted from either the inside or outside surface of a comp;,aent.
l l                                  GE'sprocedure complies with IWA-2230 by use ofan examinationfrom the inside surface.
IWA-2232 Ultrasonic Examination f
Ultrasonic examinations shall be conducted in accordance with Appendix 1.
GE's procedure is not in strict adherence with IWA-2232 or the applicable supplements of Appendix 1. Theprocedure complies with Appendix Vill, ASAfESection XI,1992 Edition,1993 Addenda andthe PDI-RPVProtocol.
!                                                                                                                                     l l
i                                  IWA-2500 Extent Of Examination Requirements for examination of welds shall apply only to weld joints and not repair welds (including core closure welds in castings) in base material, except where otherwise stated.
l GE's procedures are in compliance with IWA-2500.                                                    l l                                                                                                                                    L IWB-2500 Examination and Pressure Test Requirements i'
(a) Components shall be examined and tested as specified in Table 2500-1. The method of examination for the components and parts of the pressure retaining boundaries shall comply
;                                         with those tabulated in Table IWB-2500-1 except where alternate examination methods are      i used that meet the requirements ofIWA-2240.
l I
f i
HL-5728                                          E2-1 l
l

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i Enclosure 2                                                                                                !
Comparison of GERIS 2000 Procedures and                                                                    '
ASME Code- Section XI Requirements                                                      .
l GE's procedures are in compliance with 1WB-2500.                                                           l l
The following is a comparison of the qualified procedures (GE-UT-700 and GE-UT-701) and the requirements of Appendix I of ASME Section XI,1989 Edition, with no Addenda.
Supplement 2 l
t This supplement addresses requirements concerning calibration blocks to be used for the                    !
examination of clad welds or clad components.
Calibration blocks arefurnished by SNC. All calibration blocks with cladsurfaces meet the requirements ofthis Supplement.                                                                            )
i Supplement 3 This supplement addresses requirements concerning calibration blocks to be used for the                     ;
examination of parts with curved surfaces.                                                                 '
Calibration blocks arefurnished by SNC. All calibration blocks with curvatures meet the requirements ofthis Supplement.                                                                            l Supplement 4                                                                                               )
i This supplement addresses design requirements for the use of an alternate weld calibration block.          !
Calibration blocks arefurnished by SNC. No alternative calibration block designs as described by Supplement 4 are usedfor GERIS 20001nvesselSystem calibrations except as discussed under the Supplement 9 write-up.
Supplement 5 i
This supplement addresses requirements for the use of electronic simulators.                               ]
Electric simulators are not usedfor calibration confirmation.
I Supplement 6 This supplement addresses requirements for pulse repetition rate.
Pulse repetition rate is depned as an essential variable by Appendix VIII and is specified in the examinationprocedure. The GERIS 2000InvesselSystem was quahfied with a Pulse On                             l Position (POP) repetition rate. Each search unit ispulsed oncefor each stepposition within its              l assigned examination area.                                                                                  l
                                                                                                                       )
l HL-5728                                        E2-2

                                              .             - _ = _ .             .           .-           . ..
Enclosure 2 Comparison of GERIS 2000 Procedures and
        'ASME Code- Section XI Requirements Supplement 7 his supplement addresses requirements for instrument calibration.
Due to the design characteristics ofthe GERIS 2000 the linearity checks ofSection V, Article 4, T-431 do not verify anyportion ofthe ultrasonic system's electronics or displays, Instrument sensitivity is not dependent on any gain settings normally available to the system's operator. No linearity checks are performed as part ofthe GERIS 2000 ultrasonic calibrations.
Supplement 8 nis supplement addresses requirements for scan overlap and search unit oscillation.
Scan overlap is defined as an essential variable by Appendix Vill as implemented by the PDI protocolandis specifiedin the examinationprocedure. The GE10S 2000InvesselSystem was qualified with a maximum step size of0.25 inch which efectively determines the amount of overlap.
:        Supplement 9 l
Lis supplement addresses requirements for scan angles.
GERIS 2000 meets or exceeds the mintmas scan requirementsforpurposes ofdef7ningfull l        coverage as describedbelow:
l l        Efective examination ofthe cladbase materialinterface regionfor the detection offlaws orientedperpendicular andparallel to the weldaxis requires, as a minimum, examination by at least two 70 degree refractedlongitudinal(RL) search units. One directedparallel, and the l        other directedperpendicular, to the weld axis.
l Efective examination ofthe exam volume (not including the clad? base materialinterface region) for the detection offlaws orientedperpendicular andparallel to the weld axis requirc s, as a
,        minimum, examination by at least two 45 degree shear waves search units. One dire :ted l       parallel, and the other directedperpendicular, to the weld axis.
I        For calibration ofthe 70 degree RL search unit an alternate set ofcalibration reflectors is also providedin addition to those specified by Supplement 9. The alternate reflectors are 1/iG in.
diameter, maximum, side drilled holes installed at 1/10 in. increments to a depth of1 in. to
[        establish metalpath calibration.
Supplement 10 his supplement addresses requirements for recording data.
Method ofdata recording is defined as an essential variable by Appendix Vill.
HL-5728                                        E2-3

Enclosure 2 Comparison of GERIS 2000 Procedures and ASME Code- Sec6on XI Requirements l         The GERIS 2000 invesselSystem examination procedure requires the recording ofrelevant                        i reflectors at the 20% DAC level. This recording requirementprovides a meansfor the comparison ofcurrent examination resultr toprevious andfuture examinations.
l        All reflectors having echo-dynamic characteristics typical ofplanar indications are reviewed to l        determine their origin regardless ofasnplitude. Planar indications accompanied by tip diffracted signals are recorded regardless ofamplitude. This recording requirement is the basisfor the PDIqualipeddetection method.
Supplement 11 This supplement addresses requirements for geometric indications.
l Method and criteriafor the discrimination ofindications including geometric indications is defined as ars essential variable by Appendix Vill.
Supplement 12 This supplement on flaw sizing is in the course of preparation.
Method and criteriafor the discrimination ofindications including length and depth sizing of                   e l       flaws is defned as an essential variable by Appendix VIII.
ASME Section V, Article 4 Written Procedure Requirements T-423 (c) specifies requirement to address surface condition in the examination procedure.
l Component surface condition (examination surfaces) are the responsibility ofthe Owner.
Examination surfaces at Plant Hatch Unit 1 meet the requiremsnts ofparagraph T-441.3.1.2 Instrument Calibration l
T-431.2 requires screen height and amplitude control linearity checks.
Due to the design characteristics ofthe GERIS 2000, the linearity checks specified by T-431.2 do not venfy anyportion ofthe ultrasonic system's electronics or displays.
The screen height linearity checks specified by T-431.2.1 are applicable to ultrasonic l        instruments using integral CRT displaysfor the recording ofultrasonic data. Display i       deficiencies in these instruments may result in errors in the recorded data. Alternatively, the GERIS 2000 records data prior to CRT display and is not subject to this effect.
The amplitude controllinearity checks specified by T431.2.2 are applicable to linear ultrasonic instruments, which rely on varying dup;ay gain to provide sufficient display resolutionfor data i
HI 5728                                         E2-4 i

Enclosure 2 Comparison of GERIS 2000 Procedures and
             'ASME Code- Section XI Requirements recording. Amplitude control deficiencies in these instruments may result in errors in recorded amplitude with changes in the displaygain. The GERIS 2000 is a logarithmic ultrasonic instrument. No changes in gain are made during calibration or examination and the instrument is therefore not subject to this efect.
Beam Spread Measurements T432.3.1 and T-434, include a requirement to measure beam spread, vertical plan (T-432.3. l(e)).
These data are intended for use in comparing successive sets of system calibration data. A fiuther intent is to have these data available as more sophisticated methods of flaw sizing are developed.
Beam profile measurements are not obtainedas part ofthe quahfiedprocedure. Angle beam profile data is requiredfor amplitude based sizing techniques using beam spread correction.
Amplitude based sizing is not used. Theflaw sizing techniques used are tip difractedsi. zing techniques and are considered advanced ultrasonic procedures.
System Calibration Requirements GE'sprocedures comply with the General Requirements oft-432.
Calibration Confirmation T-432.1.2 requires a calibration check at the finish of cach examination and every 12 hours during the examination.
GE's procedures do not rely on any characteristic ofthe basic calibration blockforflaw detection or sizing and, as such, no intermediate calibration verifications are required.
Surface Finish (Basic Calibration Blocks)                                                                                1 T-441.1.2.4 requires the finish on the surfaces of the block shall be representative of the surface finished of the component.
Calibration blocks arefurnished by SNC. SNCfurnished calibrat,on blocks meet the requirements ofthisparagraph.
Recording Examination Data T-441.3.2.8 requires recording all reflectors equal to or greater than 20% of distance amplitude correction (DAC) and all surface reflectors that produce a response equal or exceeding the response from the opposite surface notch.                                                                                i GE'sprocedure (GE-UT-700) requires the investigation ofall relevant reflectors, regardless of amplitude, thatpossess the echo-dynamic characteristics ofplanar reflectors. All reflectors that are accompanied by tip difracted signals are recorded. Relevant reflectors exceeding 20% of DAC are also recorded.
l HL-5728                                            E2-5

_ _ .        . _ _ -                               .                           .  . - ~
Enclosure 2 Comparison of GERIS 2000 Procedures and ASME Code- Section XI Requirements Evaluation of Reflectors T-452 requires the dimensioning of flaws using amplitude-based techniques. Reflectors exceeding 100% of DAC are dimensioned at the 50% maximum amplitude points. Angle beam planar reflectors exceeding 20% DAC are dimensioned at the 20% DAC cnd points. Straight beam planar reflectors exceeding 50% of DAC are dimensioned at the 50% DAC end points.
GE's procedure requires the dimensioning offlaws using tip difraction techniques. Reflector lengths are determined at the 50% maximum amplitude endpoints, half-maximum amplitude endpoints, or loss ofsignal endpoints depending on the search unit angle and the flaw characteristics. This technique is considered superior :o the T-452 technique.
Summary An examination performed in accordance with GE's procedure will result in the examination volume being interrogated by the same straight and angle beam search units as an Article 4 procedure. Any areas oflimited access would be common to the Article 4 procedure.
The recording criteria of GE's procedure will result in the recording of any flaw required to be recorded by an Article 4 procedure. Flaws considerable below the 20% DAC threshold,i.e., less than 5% of DAC, are routinely recorded and evaluated with the GERIS 2000 Invessel System.
GE's flaw dimensioning techniques have been demonstrated to be within the tolerances of Appendix VIII as implemented by PDI. Article 4's flaw dimensioning techniques have not been successfully demonstrated within the tolerances in Appendix Vill.
l HL-5728                                          E2-6}}