ML20054F707
| ML20054F707 | |
| Person / Time | |
|---|---|
| Site: | Shoreham File:Long Island Lighting Company icon.png |
| Issue date: | 06/14/1982 |
| From: | Bridenbaugh D SUFFOLK COUNTY, NY |
| To: | |
| Shared Package | |
| ML20054F708 | List: |
| References | |
| ISSUANCES-OL, NUDOCS 8206170238 | |
| Download: ML20054F707 (40) | |
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UNITED STATES OF AMERICA NUCLEAR REGULATORY-COMMISSION 82 Ri15 M0:12 E-
..;. g.. : 5 BEFORE THE ATOMIC SAFETY AND LICENSING BOARD' In the Matter of LONG ISLAND LIGHTING' COMPANY
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Docket No. 50-322 (0.L.)
(Shoreham Nuclear Power Station
)
Unit 1)
PREPARED DIRECT TESTIMONY OF DALE G. BRIDENBAUGH ON BEHALF OF SUFFOLK COUNTY REGARDING SUFFOLK COUNTY CONTENTION 25 ASME SECTION XI (PSI /ISI) PROGRAM JUNE 14, 1982 l
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SUMMARY
OF TESTIMONY ON SUFFOLK COUNTY CONTENTION 25 LILCO's PSI /ISI programs for Shoreham do not meet federal requirements and have not been adequately demonstrated to be effective.
The Shoreham PSI program has been prepared and is being implemented by Nuclear Energy Services (NES).
An ISI program does not yet exist; the reason is not exactly clear.
However according to the NRC, the current practice is to wait until plant operation begins and then allow the licensee until the first refueling outage to complete the ISI program.
LILCO has stated that it will submit an ISI program six months prior to the Commercial Service date.
The incomplete program results in a number of problems.
First, the NRC has not 'been informed of location and/or extent of relief requests that might be needed.
Second, there is no certainty that the PSI and ISI programs will be compatible.
Third, each program is based on different requirements.
- Finally, l
the unavailability of the ISI program appears to make it impossible for the NRC to comply with Standard Review Plan 5.2.4.
A number of specific discrepancies are likely to exist between the PSI and ISI programs as a result of these problems.
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0 Regardless of the PSI program, it is likely that the ISI program will be ineffective once implemented at Shoreham.
There are a number of reports which question the overall effectiveness of current ISI methodology and techniques (eg.
NUREG-0313, NUREG-0531 and NUREG-0619).
The common thread in these documents is the difficulty of determining the exact nature of hidden defects in pressure boundary materials.
The NRC has issued Reg. buide1.150toimprovetheeffectiveness of the ISI program but it does not appear that,LILCO has adopted these measures.
Based on the above, the Shoreham ISI program should be completed without delay, Reg. Guide 1.150 should be utilized in this program, and a complete review should be conducted by the NRC.
Attachments:
1.
LILCO Correspondence to NRC, 7/17/81.
(SNRC-598) 2.
Shoreham Preservice Inspection Program, Appendix A.
3.
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PREPARED DIRECT TESTIMONY 0F DALE G. BRIDENBAUGH REGARDING SUFFOLK COUNTY CONTENTION 25 I
ASME SECTION XI (PSI /ISI) PROGRAh!
Q:
What is your name and position?
A:
My name is Dale G. Bridenbaugh.
I am an employee (President) of MHB Technical Associates and a technical consultant to Suffolk County (SC).
Details of my experience and qualifications have previously been submitted to the Board.
Q:
What is the purpose of your testimony?
A:
The purpose of my testimony is to address issues of concern represented by SC Contention 25 which states:
Suffolk County contends that LILCO has not adequately demonstrated the effectiveness of the technology and methods available that are required to satis fy the inspection and tests specified by 10 CFR 50, Appendix A, GDC 32, 36, 39, and 45.
The technology used for the PSI inspection for the reactor pressure boundary cannot be correlated to that used for the ISI program.
And, further, the results from inspected areas of the reactor pressure boundary cannot be extended to non-inspectable areas.
Suffolk l
County further contends that the Shoreham plant l
does not comply with 10 CFR 50.55a(g) which l
requires, for the ISI Program, use of the Edition i
and Addenda of Section XI of the ASME Code in e f fe c t 12 months prior to the date of issuance of the operating license.
Because the Shoreham piping configuration and reactor vessel design 1 !
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substantially pre-data the 1ctest code, LILCO has already identiff.ed some Section XI inspection requirements for which exemption has been requested.
Additional exemptions and/or waivers will undoubtedly be identified.
The impact of these deficiencies has not been specified and analysis has not been presented to demonstrate the effectiveness of the ISI program.
Q:
Does your experience and training qualify you to testify on this issue?
A:
I heve extensive experience in the planning, management, and conduct of nuclear plant maintenance activities, including in-service inspection work required by ASME Section XI and the plant Technical Specification.
My experience also includes work as a Field Engineer on both nuclear and fossil turbines where I frequently directed liquid penetrant, magnetic particle, radiographic and ultrasonic testing of piping and components.
I have not been certified as an inspector per SNT-TC-1A and I have therefore not attempted to conduct a detailed technical review of the inspection technology and methods planned for Shoreham.
My testimony presents, instead, my l
overall assessment of the integrated PSI /ISI program and the status of the NRC's review of the program.
i Q:
What constitutes LILCO's planned PSI /ISI program for Shoreham?
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The Shoreham PSI program was prepared by Nuclear Energy-Services for LILCO and is also being implemented by that company.
It is contained in a number of controlled documents but the master document is entitled Shoreham Nuclear Power Station Unit 1 Preservice Inspection Program Plan, 80A0482.
The latest revision I have seen is Revision 7 dated 12/16/81.
The ISI program does not yet exist.
Q:
Why is development of the ISI program important?
A:
10 CFR 50, Appendix A, GDC-32 and 10 CFR 50.55a require that the Shoreham facility be in compliance with ASME Section XI or an alternate which will provide an acceptable level.of safety.
Since the ISI program has not yet been developed, there is no assurance that this requirement will be met.
In the case of Shoreham, which i
utilizes nuclear system components predating the first 1
issuance of Section XI, it is particularly important that the program be developed and reviewed to ensure that the system can be inspected in full compliance with the Code.
To accept anything less than a Code defined program or its equivalent would j eopardize public safety as well as be in conflict with the regulations.
Q:
When should the ISI program be defined?
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A:
The NRC's Standard Review Plan covering reactor coolant pressure boundary inservice inspection and testing states that the Staff's conclusion that the ISI program is acceptable is to be based on the Applicant's program meeting Section XI, as reviewed by the Staff.
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Q:
Why is the ISI program not available?
A:
I am not sure exactly why.
However, in response to informal discovery conducted with the NRC, we were told by Mr. Hum that although the regulations imply preparation of a program prior to operation based on the Code in effect 12 months prior to the 0.L. date, that is not the practice today.
The current practice, according to Mr. Hum, is to wait until plant operation begins and then allow the licensee until the first refueling outage to complete the ISI program based on the Code (edition) in effect or noticed in the Federal Register one year prior to the 0.L. date.
Q:
What was LILCO's ISI program commitment in the FSAR?
A:
In response to Request 121.21 (page 121-21) LILCO stated that an ISI program would be submitted 6 months prior to the Commercial Service date.
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NUREG-0800, Standard Review Plan, 5.2.4, page 5.2.4-6.
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Q:
What review problems does this incomplete program introduce?
A:
A number of problems result.
Because the program has not yet been submitted, LILCO has not formally advised the NRC of the location 'and/or extent of relief requests from Code requirements that it might need.
A second problem is the uncertainty of compatibility between the PSI and ISI programs.
The PSI program is based on the 1971 Edition including Addenda through Summer of 1972.
The ISI program will probably be required.to meet the April 1980 Edition of Section XI.
The unavailability-of the ISI program appears to make it impossible for the NRC to comply with Standard Review Plan 5.2.4 which requires that the ISI program bc reviewed.
SRP 5.2.4 requires, among other things, that the NRC establish that any exemptions and relief requests are appropriate and necessary.
Q:
Can you point to any particular discrepancies that are likely to exist between the PSI and ISI programs?
A:
Yes.
LILC0's 7/17/81 letter (SNRC-598) advised the NRC of the fact that the PSI program does not include approximately 500 Class 2 5 3 component welds.
The ISI program will be required to include these components.
A copy of the letter is appended as Attachment 1.
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Are there any indications of other discrepancies in the ISI program?
A:
Yes, there are.
Attachment A to the PSI program identifies a potential problem because the vessel and certain components predate Section XI.
It is therefore likely that certain exemptions and relief. requests will be required.
A copy of that document is appended as.
Q:
Are you aware of any other problems that would indicate the likelihood of an ineffective ISI program at Shoreham?
A:
Yes, a number of reports I have reviewed question the overall effectiveness of current ISI methodology and techniques.
One such report is NUREG-0313, Material Selection for BWR Coolant Pressure Boundary Piping.
This report calls for improved ultrasonic inspection
'l methods to be incorporated in the Code.
l is a 1979 report prepared by,the NRC's Pipe Crack Study Group.
It addressed the problem of intergranular stress corrosion cracking in light water reactor piping. It also called for further development and utilization of improved NDE systems. d/
NUREG-0619 is a 1980 NRC report I
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NUREG-0313, Rev.
1, Technical Report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Pip in g, July, 1980, pp. 12 5 13.
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NU RE G - 0 5 31, Inves tigation and Evaluation of Stress-Corrosion Cracking in Piping of Light Water Reactor Plpnts, February 1979, p.
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addressing problems with cracking of BWR nozzles.
It identifies limitations existing in ultrasonic techniques that limit the inspection of nozzle bore' blend radii and recommends the continued development of UT techniques. 4/
The common thread in these documents is the difficulty of determining the exact nature of hidden defects in pressure boundary materials.
Q:
Are you aware of any regulatory steps the NRC has taken to improve the effectiveness of the ISI program?
A:
Yes.
A new Reg. Guide (1.150) was issued June, 1981 which calls for a number of improvements in Section XI or to be implemented in ISI program.
It appears to adopt some of the improvements identified in the NUREG documents identified above.
A copy is appended as Attachment 3.
Q:
Has LILCO adopted,the Reg. Guide 1.150 improvements?
A:
This Reg. Guide is not referenced in the Shoreham PSI Program description so it does not appear to be adopted.
Q:
Should it be?
A:
Yes, it should be incorporated, the ISI program should be developed, and both the PSI and ISI programs should be given a complete review by the NRC.
-4/
NUREG-0619, BWR Feedwater No::le and Control Rod Drive Return Line Ho::le Cracking, November 1980, pp. 16 5 17.
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Q:
When should this be done?
- A:
It should be accomplished before fuel loading so that any necessary modifications could be completed before the primary system becumes radioactive.
Q:
Does the NRC recognize that any'open items remain on the Shoreham program?
A:
Yes.
As discussed at the June 8, 1982 SER Open Items Meeting, PSI relief requests are still outstanding.and I
are not expected to be closed out until September at the earliest.
Q:
Does that complete your testimony?
A:
Yes it does.
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ATTACHMENT 1 SNRC-598 i
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LO NG I S LAN ID LIG HTI N G CO M PANY
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SHOREHAM NUCLEAR POWER STAT 1ON
'ht.r/.u,.w :a.u-P.O. BOX dia. NORTH COUNTRY RO AO. WACING RtVER. N.Y.11792
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July 17, 1981 SNRC-599 Mr. Harold R.
Denton, Director Office of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Commission
'-/a s hin g t on,
D.C.
20555 SHOREHM1 NUCLEAR POWER STATION - Unit 1 Docket No. 50-322
Dear Mr. Denton:
Enclosed herewith are sixty (10) ccpies of LILCO responses to specific NRC concerns which were previously identified as requirinc additional information to complete NRC review.
Attach-ment A provides a list of the specific responses included.
If you require additional information or clarification, please.
do not hesitate to contact this office.
very truly yours, Onginal sienc: by B. R. i/cCaf f re.y B.
R.MTCCEfRE 7 Manager, Project Engineering Shoreham Nuclear Power Station C
.: > RWG/mh Enclosures cc:
J.
Higgins t
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E.
J.
Ycungling (w/ attach)
A.
E.
Pedersen 1
Dist. List 114 (w/o attach)
Eng. File /SR2...A21.010 (w/attich)
l ATTACHMEtlT A
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Additional Information is provided for the following items:
1-dSELOpfirl lje lil.9 - %shrdireilnop_Qionj i J 2.
SER Open Item #35 - Containment Isolation 3.
SER Open Item it9 - 0.C. System Monitoring 4
SER Section 6.3.1 5.
ilUREG-0737 Item 1.G.1 - Training Recuir ements During Low Power Testing 6.
flVREG-0737 Item II.E.4.2 - Containment Isolation Dependability s.
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item #19 - Preservice Inspection Shoreham's Pre-Service Inspection Program was written to be in compliance with the requirements of 10CFR50.55a.
Accordingly, tne technical basis for the Program was the 1971 Edition of ASME Section XI through the Summer,1972 Addenda, and augmented examinations as stipulated in Shoreham's FSAR.
The Shoreham Pre-Service Inspection Program, first submitted to the Commission on March 16,.1978 has always clearly indicated that the 1971 Edition of ASME Section XI through Summer, 1972 Addenda, forms the basis for the PSI Program.
Using the rules of this Edition of Section XI, components subject to pre-service examination
,are essentially limited to Class I ccmponents.
(A detailed list of ccmponents subject to examination is contained.in the Pre-Service Inspection Program Plan).
It is recognized that the rules for in-service insoection at Shoreham will require examination of Class 2 and 3 components in addition to the Class 1 components included in the Pre-Service Inspection Program Plan.
In-anticipation of this requirement, Class 2 and 3 welds which will require in-servide examination have been visually inspected to assure adequacy of both accessibility and weld preparation for subsequent in-service examination.
In this manner, the inspectability of welds anticipated to require in-service examination has been assured.
Therefore, one function of pre-service inspection, to assure that accessability and weld preparation is sufficient to permit in-service examination, has been fulfilied at Shoreham.
The assurance that the initial, or base-line, quality of co'mconents at Shoreham is sufficient to permit safe operation of the facility' has been achieved through the aoplication of the examination recuirements of Section III of the ASME Code during construction and fabrication.
The adequacy of this program at Shoreham can clearly demonstrate by review of the pre-service examinations completed at Shoreham to date.
With ove.r 90% of the approximately 1,036-piping weldi required to be examined by the PSI Program Plan now ccmolete, no rejectable indications have been detected.
This fact provides a higE~ level of confidence in the construction program utilized at Shoreham.
If, for example, the above data were applied as a sample size in accordance with itIL-STD-1050, it would provide acceptance for a lot size of up to 50,000 welds.
Since there are pr'esently less than 500 Class 2 and 3 welds anticipated as requiring in-service examination, it is conservative to assume th=r no rejectable indications would be detected through pre-service examination of these welds.
This conclusion is reasonacle, particularly in light of the well documented NDE required and successfully l
completed by the cons truction and fabrication ornaram a t Shnrahim.
r.
Typically, non-destructive examination acceptable.to Section Xr have already been performed for Class 2 and 3 components as a result of the construction and fabrication programs.
In some cases, the NDE technique employed during fabrication and/or construction is rot the same as the one anticipated to be used during in-service examination.
llowever,Section XI clearly recognizes that the application of acceptable alternate NOE techniques will not alter the level of confidence achieved.
For this reason, N0E already performed on Class 2 and 3 components should provide an adequa te base-line or initial level of quality for. in-service inspection purposes.
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r ATTACHMENT 2 SHOREHAM PSI PROGRAM, APPENDIX A t
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EXEMPTIONS AND EXCEPTIOt3S The effective date of the Shoreham Nuclear Steam Supply System Contract was December 10, 1968, which is approximately 1 year prior to the initial publication of the " Draft ASME Code for Inservice Inspection of Nuclear Reactor Coolant Systems" issued for trial use and comment.
It should be recognized, therefore, that the design of the primary containment and the design and fabrication of some pressure-containing components of the reactor coolant system were far advanced at the time of publication of this draft code and could not be changed without significant redesagn or the plant.
Since the Shoreham Nuclear Steam Supply is a 1967 GE product line, 1000 access to the reactor vessel surfaces, as stipulated by IS-142 (a) of Section XI, is not feasible because the basic design was finalized prior to the adoption of the applicable Section XI requirements.
- However, design features have been incorporated to provide access for preservice and inservice inspection to comply as fully as possible with Section XI.
In addition, all Reactor Pressure Vessel (RPV) welds that would become in-accessible (manually or with automated equipment) subsequent to field installation, were manually examined prior to vessel setting to provide an essentially 100% coverage of the R9V welds for the Preservice Inspection examinations.
l The methods of examination for some categories defined in Table IS-261 of Section XI have been taken exception to, and alternate examination methods substituted, where'ver possible.
In addition, certain Section XI requirements have been ex'cluded from the preservice inspection program as they are not applicable to SWR's or to Shoreham components specifically.
Full details en all exemptions allowed by Section XI paragraph IS-121 are provided in Table.A-1.
Included in this table is the exclusion size j
that has been calculated by Stone and Webster to be 1.12 "ID for liquid i
carrying piping and 2.24" ID for steam carrying piping.
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Table A-2 lists those areas where relief from the ASME code requirements is being requested.
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TABLE A-1 EXEf'.PTI O!:S SilOREilAt4 PRESEr 5 4 CE Ir:SPECTIO!J PRCGRAl4 REASO!1 CODE CO!iPOi!EllT CATEGORY FOR EXEt4PTIOt1S DESCR1PTIOlj SYSTEta Al1 Liquid 1ines 1.12" ID and J-l AS!4E Section XI 1971 with 1972 addenda paragraph IS-121 smaller and steam lines 2.24" (a)
I D cud small er J-l LSt4E Section XI 1971 wi.th Piping beyond the Second Sunener 1972 addenda, paragraph Al1 i solation val've' IS-121 (b)
J-l ASt4E Section XI 1971 with Con.ponents 1" nominal pipe Suminer 1972 addenda, paragraph All size and smaller 15-121 (c)
Containment penetration flued E-1 Welds will be examined in accordance with ASME Section Al1 head inner circumferential
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XI 1977, Sunener 78 addenda attachn.ent weld t o piping (credit will be taken for HT (see Fig. A-1) exam performed during con-struction)
Cid) (137) and in-core monit or E-1 Shop examination records RPV,
used in lieu of Preservice housing (4 3) penetrations examination.
ASt4E Section XI (stub tube-to-housing and 1971 with Stumner 1972 addenda, vessel welds) paragraI>h IS-232 RPV Drain nozzle (1) to E-l kPV vessel weld Instrumentation nozzle C-1 RPV to RPV weld ( p ).
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TABLE A-1 EXE!PrIO!!S SliOREllAM PRESERVICE II;SPECTIOli PROGRAM COMPOIENT CODE REASON SYSTEM DESCRIPTIOf1 CATEGORY POR EXEMPTIOllS All Liquid lines 1.12" ID and J-l ASME Section XI 1971 with smaller and steam lines 2.24" 1972 addenda paragraph IS-121 ID and smaller (a)
All Piping beyond the second J-l '
ASME Section XI 1971 with isolation valve Summer 1972 addenda, paragraph IS-121 (b)
Al1 Components 1" nominal pipe J-l ASME Section XI 1971 with size and smaller Summer 1972 addenda, paragraph IS-121 (c)
All Containment penetration flued K-1 Welds will be examined in (except Hecirc) head inner circumferential accordarice with ASME Section attachment weld to piping XI 1977, Summer 78 addenda (see Fig. A-1)
(credit will be taken for MT exam performed during con-struction)
RPV CRD (137) and in-core monitor
-E-1 Shop examination records housing (43) penetrations used in lieu of Preservice b
(stub tube-to-housing and examination.
ASME Section XI vessel welds) 1971 with Summer 1972 addenda, paragraph IS-232 RPV RPV Drain nozzle (1) to E-1 vessel weld i
RPV Instrumentation nozzle E-1 to RPV weld (6) p e==-
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TABl.E A-1 EXEMPTIO!!S SliOREllA!4 PRESERV3CE It!SPECrJGi PROGRAF 4 i
CU4PO!!EllT CODE REASOil 1
CATEGORY' FOR EXEliPTIQ4S SYSTEf4
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DESCRIPTIOli s
CorebPnozzleto E-1 Shop exaraination records
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RPV used in lieu of Preservice j
. examination.
ASl4E Section XI 1
1971 with Stumner 1972 addenda,
' paragraph IS-232 E-1 y
ITV CRD llousing Plange and Intemediate veelds i
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TAblI A-2 RELIEF REQUESTS Al.ITY CG '.PC E:Ettr CODE REQUIRED II: 1.IED &
PEASCd FOR DRAWIllG CATEGOltY CODE E)'Ati EXAf4 RELIEF 11 0.
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ATTACHMENT 3 REG. GUIDE 1.150 I
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- f U.S. NUCLEAR REGULATORY COMMISSION June 1981 (Mf4 REGU D? TORY?GillDE b.....
OFRCE OF NUCLEAR REGULATORY RESEARCH' * "m'i...., '..
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R EGU LATORY GUIDE,1,150 _,,,,,,;, g,s. i, gu,.,
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.m i >.i t mt w (A i i r.r,' i ' u tt.t he i d.i.1 ULTRASONIC TESTING OF RE ACTOR VESSEL WELDS DURING PRESERVICE AND INSERVICE EXAMINATIONS n..
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- o.. e. h i, A. INTRODUCTION Criterion XVil,"Quali dix B requires,in part, th,tyAssurance Records,l$of,,App at sufficient reco,rds be,ma,intained Criterion I," Quality htandards and Records," of Appen-to furnish evidence of activities affecting quality,, Consistent dix A, " General Design Criteria for Nuclear Power Plants,"
with applicable regulatory,,requirerpent,s..the, applicantjs to 10 CFR Part 50, " Domestic Licensing of Production and required to establish such requirements concerning record Utihzation Facilities," requires, in part, that components retention as duration, location, and assigned responsibility, importar.t to safety be tested to quality standards commen-
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performed. Where generally recognized codes and standards This guide describes proced: ires acceptable to the.NRC are used, these codes and standards must be' evaluated to staff for implementing the above requirements with regard determme their adequacy and sufficiency and must be sup-to' the preservice and inservice exatainations of reacto'r piemented or modified as necessary to ensure a quality pro-vessel welds in light water-cooled nucle:.r power plants by Juct in keeping with the required safety function. Criterion 1 ultrasonic testing (UT). The scope of this guide is' limited to further requtres that a quality 2ssurance program be imple-reactor vessel welds and does not apply to other 'strtictures mented in order to provide adequate assurance that these and components such as pipmg.
',. a* n.. *t i... a components wd! satisfactortly perform their safety functions and that appropriate records of the testing of components
,,,i r important to safety be maintained by or under the control B. DISCUSSION i,,,, t,.
of the nuclear power unit licensee throughout the life of i
.i,,.
the unit.
Reactor vessels must periodically be volurnetrically examined according to Section XI of the ASME Code.
Section 50.55a, ' Codes and Standards," of 10 CFR which is incorporated by reference, with NRC staff modik.c Part 50 requires, in part, that structures, systems, and tions,in } $0.55a of 10 CFR Part 50. The ru!cs of Section XI components be designed, fabricated, erected, constructed, require a program of examinations, testing, and inspections tested, and inspected to quality standards commensurate to evidence adequate safety. To ensure the continued with the importance of the safety function to be performed.
strtictural integrity of reactor vessels, it is essential that Section 50.55a further requires that American Society of flaws be rehably detected and evaluated. It is desirable that Mechanical Engmeets Boder and Pressure Vessel Code results from pnor UT exarr.inations be compared to results (ASME B&PV Code) Class I components rneet the require-from subsequent examinations so that flaw growth rat:5 ments set forth m Section XI," Rules for Inservice Inspection may be estimated. Lack of rehabdity of UT examination of Nuc! car Power Plant Components," of the ASME Code.
results is partly due to the reportmg of ambiguous results, such as reporting the length of flaws to be shorter during Criterion XII," Control of Measunng and Test Equipment,'
subsequent examinations. This lack of reproducib'ity ariscs d
et Appendix 11. " Quality Assurance Criteria for Nuc! car because the Code requirements are not specific about Power P! ants and Fuel Reprocessmg Plants," to 10 CFR many essentialvariables m the UT procedures. Recommenda-Part 50 requires, m part, that measures be established to tions of this guide provide guidance that would he!p to ensure that instruments used in activitics affecting quality obtain reproducibility of results. Reporting of UT indications are properly contro!!cd, calibrated, and adjusted at specified as recommended in this guide will help to provide a means periods to ma'ntain accuracy within necessary limitt for assessing the ambiguity of the reported data.
USNRC REGULATO AY GulCES Comment s snousd De sent to tne SeCretarv of tne Commission.
u.S. NuCiear R egula tory Commr$5lon. W a sningt on, O.C. 20 5 5 5, Re9ulatory Guides are istund to cascrfoe and mase avallaole to tne Attentions Docketmo anc SerwsCe aranCn.
Q u OllC met %15 aC Ce p t aDie to the NRC starf of im plemen ting bd 6C l f lC part 5 Of tne Commf113On's regulations, to defineate tecn.
Tne guides are issued in tne foi owing ten Droad dlwillonti niquel uned Dp (no llaf f gri evaluating toeCitic OrcOlems Gr OOntu-lateG ACCidants of f3 DrQvide guidance to 4D0llCan'.1. Regulatory
- 1. Power neactort t
- 6. ProduCtB Guides are nul suuntitutes for regulations, and Compliance wa t n
- 2. ResearCn and Test Aeactors
- 7. Transoortation itsom is nut agoulted. Vetnudl and Solutions dif ferent f rom incto not
- 3. duelt and Materials FaClllllel S. OCCupationae wealtn Out :n the Guides will be ACCeDtable if tney Drovide a 04135 for t'se
- l. E9w.ronmentas and S.ttng
- 9. Antitrust and F'nancial Aew!aw f tncings recussite ta tne issuance or Continuance of a permit ur
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Copies of issued guices may ee ourCnased at tne Current Government Init guide was visued af ter Consideration of Comments received from Printmg Of tlCe DelCo. A luCf Cr Dtfon ServlCe for f uture guldet in 500-t il e GuDelC. C ue n me n t h and sugge$tions for improvements in tnese CellC Jivlilunt ll avatlebie tnrQuyn tne GJweenment l*r!nting Of fsCa.
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araQ guedet weall be reve6ed, al Information On tne subscription servtce and Current Gpo prices may aoleroDelete to acCQesunuelate Cuestments and to reflect new enforena-be uDtained by n;4tsng tr Regulatory Commission, D.C. 20 313,'s t.:.S. PeuCreat liten Qr em perience.
W ann ines t on, Attentions Pu DelC a tion s sales Manager.
Operatmg and licensing 'experienee.2.3 and industry performance characteristics (amplitude linearity and t
4 teus have indicated that UT procedures that have been amphtude controllinearity)is to be verified at the beginning us d for examir,ation of reactor vessel welds may not be of each day of examination. Requirements in Artic!< 4, adsquate to consistently detect and reliably characterite Sectiun V,1977 edition, which is referenced by Section XI, flaws during inservic:: e4Jmination of reactors. This lack of h>r the periodic check of instrument characteristic $ (screen reproducibility oflocation and characterization of flaws has height hnearity, amplitude control lineartty, and beam resulted in the need for additional examinations and spread measu r e men ts) for UT examination of reict:,r,
naluations with a>>ociated delays in ths licensing process.
pic>>ure vesse!s have been relaxed. The interval between ;
periodic checks has been extended from a period of I day
- 1. INSTRUMENT SYSTEM PERF01(MANCE CllECKS tu a period of extended use or every 3 months, whichever is less. This change has not.been justified on the basis of Instrument system performance checks to determine the statistically significant field data. Performance stability of characteristics of the UT system should be performed at autumated electronic equipment is dependent on system mtuivals short enough to permit each UT examination to be performance parameters (essential variables), and the ASME -
eurtelated with particular system performance parameters to Cgde has no quality standards to control these perfurrnance help compare results. These determinations will help make it parameters. Until the performance stability of UT systems-possible to judga whuther ditferences in ohwrvations made can be ensured by the introduction of quality standards, at du farent times are due to changes m the mstrument system it is not reasonable to mcrease the period between calibration char etenstics or are due to real changes in the Oaw size and cliccks. Therefore, recommendations have been made to shractertsues. Determinations for " Frequency Amphtude check instrument performance parameters more frequently Cmve" and "l'ulse Shape" recommended in regulatory posi-than is speettied in the ASME Code.,
uuns l.4 and 1.5 may be made by thclicensee's examination
. gent by using any of the common industry methods for Requirements of Appendix 1, Article 1,14230, Section X1 measur ng th::>e paraineters as long as thew methods are of the ASME Code,1974 edition, state; adeuuately documented in the examination record. The>e mea >mements may be performed in the laboratory bef ore-
" System calibration shall be checked by verifying' the and af ter eJeh examination, provided the identical equip-distance amphlude correction curve (14420 or 1-4520) ment combbiation (t.c., instrurnentation, cable, and search
.md the sweep range calibratton (14410 or !-4510) at the umt) n used durma the examination.
Start and finah of each examination, with any change in examination personne!, and at least every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> during '
Thew Jeterminations are to aid third party evaluation
- ao exammation."
when differ:nt equipment is used to record indications on sulnequent examinations and are not intended to quahfy in the 1977 edition, these requirements were changed, miems f or ox-Accordmg to Artte!e 4 (T-432.1.2),Section V of the ASMl!
.l.he intent of regulatory position 1.3 ts to establish the Code,1977 edition, the following apples:
}
r insuuinent pulse shape in a way that actual values of pulse "A cahbratio'n check on at teast one of the bas.ic re0cctors '
'tnc'th and voltages can be observed on an osedloscope..!he caubrated time base does not necessardy have to follow the m the baue cahbration block or a check usmg a simulator tune ba2e ut the datance-amphtude correction (DAC) cutNe but shat! be made at the finish of :ach exammation, every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> durmg the examination and when examination niay he chosen to suitably characterite the tmttal pulse. I he puhe shape record wdl.,unt in analyting potential dit ferences personnel are changed.,,
m llaw respun>e between suaesuve exanunationso.e., a the Ollierence due to llaw growth or system change),
This requirement has several minor deficiencies, including the following.
l'ulse shape is best determined by using a high impedance owilluscope with the transducer Jiwonnected from the
- a. One Point Check msuoment.
A cahbration check is now required on only one of the
- 2. C A L.! nit ATION uue redectors. As a result, the iceuracy of only one point un the DAC cune, and not the accuracy of three points as A;corthng to Appendix 1, Artie!e I,1-4230,Section XI of prevmugy req u ire d, is checked. Thu atteration would the AS'd h Code, 1974 edition, instrument calibration for per:mt the m>trament dr:It for ather metal [ath distances to go annatteed, wluch a not des rable.
'"tfu rnunie M en.>pec ono ur tmgrun i neactor Venet Nonic mu." man u. Cau, Nu uCC45ut
- b. Secondary Reference
""knnury tblgh Nu6tcar Pbut Unit t Itcaetor l*fesaure VC>>cl aspur," i m, Cenwa Pomr can.p.ay.
The change a!!ows a onSpaint check by a mechanical C hum.ry ur on: Octcction and Euluanon ur tdtranunie or c!cetronic nunu!ator mttead 0 ' Eh#Ek US'*II Ih* b' sic t
i.a n,ons Glwin I b M b r,t t ion bloet. A mechanic.Il simu!ator COu!d b* a I i.., t es orgb Puwer L_tg3 % g t R enu,r Frenarc Vgsast," J an uary 1
um pan y.
p!,nhe, sted, or aluminum block with a smg!c reference 4 R o u n si robin auta conJostcJ t y the Prn2urs Vn.ci Reisarsh tellector, which may be a hole or a notch. Without specified C.n.noa t es O'V n C) ut the Miamg R osarca Luunsd for U f ut oaa su nun stui>.
J e t.nl a, the electronic >imulator could be any device that
J provides an electrical signal. With the resulting uncertainty, dropped) during transport than those parameters that there may be errors in checking against the secondary served as a casis for defining the error band.
,[
, reference (simulator), the m.ignitude of which is undefined and unknown.i Use of electronic simulators would be perrnissible if ~
i i e '.A ' '
they can check the calibration of the UT system as a whole
.c. Electronic Simulator.
and the error band introduced by their use c,an be relied on and taken into consideration.
.y.
. t ! Subartic!c T-432.1.3 of Article 4,Section V of the 3"
f\\SMli Code,1977 edition, at!ows the use of an electronic d, Static Versus Dynamic Renector Responses ' ' ' ',
i
. simulator and also permits the transducer sensitivity to be C
checked separately. Both these provisions may introduce
- With so le automated systems, the DAC curve is
.
- errors that wdl be very difficult to detect.
manually establ shed. In these cases, the signal is maximized by optimizing the transducer orientation toward the
,',: " To ayoid the. introduction of errors and to ensure calibration holss. Subsequently, detection and sizing of
. repeatability of examinations at a later date, it would be flaws are based (n signals received from a moving transducer
. advisable to check the calibration of the entire system where no attemi t is made (oritis not possible) to maximize,.
- rather than that of individual components. Checking system the signal even for significant flaws. This procedure neglects 1calibtution without the transducer and the cable is not several sources of error introduced by the possible variation advisable because these tests do not dctect possible leakage in signal strength caused by
' or reustance. changes at the connectors. This is especially 4
.important when the UT examination is performed under (1) Differences between the maximized, signal conditions of high humidity or under water and the connec-and the unmaximized signal.
lors may not be waterproof or moistureproof. Checking the transducy sensitivity separately (sometimes weeks in (2). l.ossin signal strength due to the separation of advimce) also neglects the effects of possible damage due to the transducer from the metal surface because transport or use. The transducer charactenstics may change of the viscosity of the coupling medium (plan-because of damag: to or degradation of internal bonding ing effects),
I acents or inadvertent damage to the transducer c!cment.
l?urther, the use of an electronic block simulator (fiUS) as a (3) Vanation in contact force and transducer secomlary standard introduces an error band in the calibra-coupling efficiency, tion precen.The error band may depend un, among others, the fnlinwing factors:
(4) 1.oss in signal strength due to structuralvibra-4 tion effects in the moving transducer mount (1) Drift due to ambient temperature change.
and other drivmg mechanisms.
l (2)
Drift due to high temperature sto} rage.
i (3) Dnit due to high humidity storagg.
(,5)
Loss iri signal strength due to the tilting caused
-(4)
Dntt due to vibration and shock loading during by the mounting arrangement in some trane shipment.
ducer mounts, i
(5) Degradation of the memory device used to store the reference signal information due to vibra-Because of the above,it would be advisable to establish j
ttnn, shock, aging, or heat etfects.
the DAC curve under the same conditions as those under l
which scannmg is performed to obtain data for detection To ensure stability. computer systems are generally.
and sizing. It would be acceptable to estabush a DAC curve kept in an att conditioned environment; however, EUS by maxumzing signal strength durmg manual scans when systems are not usually kept in a controlled environment.
signals are also maximized for flaw sizing. Ilowever, it would not be advisable to use manually maximized signals 5
Error band for one particular type of instrument to establish the DAC curve when dar3 Jre obtained later by j
was determined to be m the range of 16 percent. The error mechanized transducers (where signals cannot be maximized) band for other instruments may be in a different range and for the detection and sizmg of flaws without adjustment for may vary for the same instrument if memory devices or the potential error introduced. In these situations,.m components of differsnt qu.dity are used at a later date, acceptable method would be to estabbsh DAC curves using The error band is dependent on the temperature extremes, movmg transducers or to estabbsh correction factors that sh oet, loathugs, and vibrations suffered by the instrument.
may be used to adjust signal strength. It would be prudent j
Since the error band value depends on these parameters,it to use care and planning in establishmg correction factors.
~
would be admahic to ensure, through recording mstruments, lior exarnple, establishing a ratio between a dynamic and that the fills was not subjected to higher ternperatures static mode under 12botatory condittons using a precision i
(cuntainer lying in the sun) and greatar shoek (container transducer drive and stif( mountmg may have very little in 4
common with the transducer mounting and traverse conde tions of the actual examiEation setup. If correction factors "C.bbranun Wu6 anon ut Uhrnunic thammanon Systems wnh are to be used, it would be worthwhile to budd eithe*
tt s thnoim: mi,s k sun,t.ior." D. L Doomsard e s.t.. A uguie t *>7 '.
full scale mockups or consider the vanation of all the
.%, suus t Nu.WL'A t'.*> >4 s. Weatusghuus t lschic Carpuratiun, Nuclear s viu lhvtuon, l'.O. no a 272 s. nusburgh, l'A i s no, important parassieters in a suitable model taking into
consideration scaling laws o4 variabics such as mass, vibration, holes; however, if the talock or these holes are polished, this and stiffness constants. It would be advisable to confirm the fact should be recorded for consideration if a review of the sealing law assumptions and predictions for vtbration and UT data becomes necessary at a later date..
viscosity stfects before co seanning sensitivity levels.frection f actors are used for setting
- 3. NEAft SUltFACE EXAMINATION AND SUltFACE ItESOLUTION Differences in the curvature and surface finish between i
. calibration blocks and vesselareascould change the dynamic Sound beam attenuation in any material follows 'a l
response, so it may be advisabic to estabiish correction factors decaying curve (exponential function); however, in some ;
between dynamic and static responses from the indications
. cases the renection from the nearest hole is smaller than the that are found during examination.,This would avoid the retlection from a farther hole. This 'makes it difficult to '
difficulties associated with establishing a dynamic response draw a proper DAC cune. In such cases,it may be desirable j
DAC cune and still take all the factors into consideration.
to use a lower frequency or a smaller transducer for flaw g
detection near the beam entry surface to overcome the
- c. Sceandary D AC,
difficulty of marginal detectability.
,.e e.:
. E f, I/
Durine some manual scans, the end point of the DAC Near field effects, decay time of pulse reflections, curve muy,all below 20 percent of the full screen height, shadnw effects, restricted access, and other factors do not When this happens, it is dtfricult to evaluate flaws on the permit effective examination of certain volume areas in the 20 percent and 50 percent DAC basis in this region since component To present a clear documentation and record the 20 percent and 50 percent DAC points may be too close of the volume of material that has not been effectively to the baseline, To overcome this difficulty,it is advisabic examined, these volume areas need to be identified. Recom-
~
that a secondary DAC cune using a higher-gain setting be mendations are provided to best estimate the volume in the developed so that 20 percent and 50 percent DAC points may region of interest that has not been effectively examined, t>e casdy evaluated. For this purpose, it is advisable that the such as volumes of material near eacit surface (because of gain be increased sufficiently to keep the lowest point of near4ield effects of the transducer and rmg-down effects of t
the secondary DAC curve above 20 percent of screen height, the pu!>e due to the contact surface). volumes near interfaces between cladding and parent metal, and volumes shadowed j
The secondary DAC curves need not be generated by laminar lla ws.
unless they' are required. If electronic DAC is used and 6.c
.nnphtudes are maintained above 20 percent of full sercen
- 4. I!EAh! PROFIT.E i
height, a secondary DAC would not be necessary, Ileam profile is one of the main characteristics of S lians.
- f. Component Substitution ducer, it helps to show the three-dimensionaldistribution of beam strength for comparing results between examinations.
A calibration check should be made cach' time a and aho for characterizing flaws. The beam profi!c needs to,
component is put back into the system to ensure that su;h he determined and recorded so that comparisons may bc j
components as transducers, pulsers, and receivers were not made with results of successive examinations, da maged whde they were in storage. This wdl ensure i
etunination of the error band and mistakes in resetting the
- 5. SCANNING WELDAIETAL INTERFACE vanous control knobs.
The amount of energy ' reflected back from a flaw is
- g. Cashbration lloles
, dependent on its surface characteristics, orientation, and size. The present ASN!6 Code procedures rely on the Comparison of readts between examinations perfornied amplitude of the reflected signal as a basis forjudging flaws, at different times may be facditated if the same equipment This means that the size estimation of a defect depends on is used and if the retlections from growing Daws can be the proportion of the ultrasonic beam reflected back to the l
compared to the same reference signal. Reference signals piol,e. The redection behavior of a planar defect, which obtained from a caltbration block depend on, among other
!.ngely depends on the incident beam ang!c when a single things, the surface roughness of the block and the redector search unit is used to charactertze the flaw, is thus a decisive he,'es. Therefore, these surf aces should be protected from f actoi m flaw estimation. The larger the size of a planar worrosion and mechanical damage and also should not be de fect, the narrower is the ref;ected sound beam. The Itereu by mechanical or chemical means between successive narrow redected sound beam makes the Gaw very difficult mminations, if the reference re0cctor holes or the block to detect m most cases (unless the beam angle is right).'*7 suitace are gwen a high pothh by any chemicalor mechanical means, the amplitude of the redections obtained from these t
istlector holes may be altered. Polishing the holes or the
'"Pruhat> int y of D5.cenng lianar Defecis in ifcavy Waa Welds by block surf ace is not foibidden by the ASstE Code. !!owever' Unmunic Technnmn Amdmg toksunng Cades," Dr. Ing. Ilans-L.ron Mcyer. Quainy Department of M.A.N., Nurnocrc. 01500 lb pombly altered amplitude could affect the sizbig of
%rnusrg ii s.
I unlications found during any examination. At this time, no secommendations are being made to control the surface y"Regeti n of Ultras nje Puhes from Surracea," lfaines and t..noion unir t Eicecrieny wncreting Huntd. U.K. (CESD) Report sounhnen of the block or the above mentioned redector N mnher n u ti/rn als.
l
i t
j Therefore, the beam ang!cs used to scan welds should be has to be considered in judging the significance of flaws.'
optimized 'and should.be based on the geometry of the it is therefore recommended that only signals with a total wJd/ parent metal interface. AL icast one of these angles transducer travel movement greater than the beam spread
.should be such that the beam is almost perpendicular ( 15 should be considered significant.
degrees ' to the; perpendicular) to the weld /paren t-metal
.is interface, unless it can be demonstrated that large (Code-
- 7. REPORTING OF RESULTS '
a.t unacceptable) planar flaws unfavorably oriented, parallel to l
the weld metal interface, can be detected by the UT tech.
This guide gives recommendations for recording the chTrac-nique being used. In vesselconstruction,some weld preps are teristics of the UT cxamination system. This information,
essentially at right angles to the metal surface. In these cases, can be of significance in later analysis for determining the
' use of sheatiwave angles close to 75 degrees is not recom-location, ' dimensions, orientation, and growth rate of 0aws.
mended / Two' factorsEwould make the use of shear wave
.h -
angles close to 75 degrecsinadv(able,- first, the test distances Records pertaining to UT examinations should be con-.
necessary become too large resulting in loss of signal, and sidered quality assurance records. Recommendations on the second, the generation of surface waves tends to confuse collection, storage, and maintenance of these recor'ds are the interpretation of results; in these cases,use of alternative given in Regulatory Guide 1.88, " Collection, Storage, and volumetric nondestructive examination (NDE) techniques,i Maintenance of Nuc! car Power Plant' Quality Assurance Re-as permitted.bylubarticle IWA 2240,-Section XI of the cards." Availability of these records at a later date will permit AS',lE Code,. should ; be. considered. A!ternative NDE a review of the UT results from the data gathered during techniques to be considered may include high intensity previous ultrasonic examinations.
radiographior tandem probe ultrasonic examination of the weld metal interface. To avoid the possibility of missing When ultrasonic examination $ performed, certain vol.
large flaws, particularly those that have an unfavorable umes of material such as the following are not effectively orientation, it is desirable that the back reRection amplitude, examined:
whde scanning with 4 straight beam, be monitore! over the untire volume of the weld and adjacent base metal. Any
- a. Material volume near the front surface because of near-area where a reduction of the normal back9urface redection ticld effects, cladding disturbance, or electronic gating.
amplitude execeds 50 percent should be examined by angle beams in increments of 115 degrees until the reduction of
- b. Material volume near the surface because of surface signal is explained. Where this additional ang!c beam roughness or unfavorab!c flaw orientations.
exanyination is not practical,it may be advisabic to consider examWing the weld by a supplementary volumetric NDE
- e. Volumes shadowed by insulation c part geometry, technique.
In some cases, as much as I inch (25.4 mm) ur more 6, SIZING below the surface is not examined because of the electronie gate setting. This means that the unexamined volume nray Thidepth or th' rough wall dimension of flaws is more euntain Daws that would be unacceptable according to i
significant than the length dimension, according to fracture Section XI, ASME Code, as follows:
mechanics analysis criteria. Usmg the sing!c probe pulse-echo technique, it is possible, depending on flaw orientation,
- a. Without evaluation (deeper than approximately 0.2 i
that some lar:e Daws may not re0cct much energy to the inch).
l icarch unit." llecause of this possibility, the depth dimen-l sion of the Gaw should be conservatively sized unless there is
- b. Even after evaluation (deeper than. approximately evidence to prove that the Gaw orientation is at right ang!es 0.85 inch).
l to the beam. It is recommended (Nt indications that are asso-l eiated with through thickness Daws and do not meet Code-Assuming an aspect ratio of 0.I, according to IWB 3510.I, i
allowable critena or criteria recommended in this guide be Sectiun XI, ASME ' Code, flaws 0.2 inch deep would be steed at 20 percent D AC as well as at 50 percent DAC.
unacceptable for a 9-inch wall thickness, in certain cases, it is possible for various reasons that a Typically a BWR reactor pressure vessel (RPV) wall in j
flaw would not rc0cet enough encri;y to the scarch unit to the beltline region is 6 inches thick and a PWR RPV wallis make the indication height 50 percent of the DAC curve 3.5 inches thick. During Daw evaluation, where the wall j
height. lloweser, if such a llaw were large, a persistent temperature is high and the avadable toughness is high,. and stenal could bc obtained over a large area, it is therefore the calculated critical surface Oaw depth (a ) exceeds the wa!!
9 g
iccommended t' tat all continucus signals that.:re 20 percent thickness (t), a, is taken as the wall thickness. According to ut D AC with transducer travel movement of more than
!WB 3600, SecIlon XI, th:1 a!!owab!c end-of life size is ag =
l 1 inch plus,the beam spread (as defined in Artic!c 4, non-0.la. Flaw. exceeding this a!!owable value, which would g
m.mdatory Appendix 0,Section V of the ASME Code, 1977 edition) should be considereil sigrtficant and should
"" vier.onu Exwunscion cdprison orInctestkn md Actua n.w be recorded and mvestigated further, l'he beam spread m kl"6" hhi Ka*Cun.4f arima industries Co., tr1, J nuary 1976.
efrect in some cases can make very small Haws appear to be I
9-Maw livau.oon Pnxedures: ASME S sion XI EPRI," NP 719-SR, targe when judged at 20 percent UAC, hence, beam spread inci.i rm,rs. Aucuni i ns.
. - = - - _,. - _ _. - -
be 0.35 inch for a PWR and 0.65 inch for a 13WR, wdl have 1.3 Amplitude Control Linearity to be repaired. The above example i!!ustrates theimportance of blanking out the electronic indication signals and not Amplitude controllinearity should be determined according examining the surface volume to a depth of 1 inch. Since' to the mandatory Appendix !! of Articic 4,Section V of*the the flaws that can be missed because of electronic gating may ASM E Code,1977 edition, within the time limits specified in be larger than the flaws permitted with or without evaluation, regulatory position 1.1.
p.
Ihis unexamined volunn:is important and needs to be identified.
o In L certain : specific. cases, areas were not examined I.4 Frequency Amplitude Curve.
I *
...[.
because insulation was in the way and the transducer could j, '-
not scan the volume of interest. NRC was not informed of' A photographic record of the frequency-amplitude curve thisiituation until much later. In view of the above and to should be obtained. This record should be available for aeoid licensing delays, it is advisable that the volume of areas comparison at the inspection site for the next two successive not examined for any or allof the above reasons be reported.
inspections of the same volume. The reflector used.In
" The volumes of ; y generating the frequency-amplitude curves as well as the
~
material that are not effectively examined electronic system (i.e., the basic ultrasonic instrumento depend on th.: particular part geometry and unique situs-gating, form of gated signal, and spectrum analysis equip.
Lions associated with each RPV. During identification of ment) and how it is used to capture the frequency-umplitude the material volumes that have not been examined, considera-information should be documented.
tion shnutd be given to the types of flaws that are currently being reported in some of the operating plants. Tyse include stress corrosion cracks in the heat-affected zone, 1.5 Pu!.te Shape fatigue cracks, and cracks that are close to the surface and sometimes penetrate the surface. These volumes of A photographic record of the unloaded initial pulse.
matenal should be identified and reported to NRC along against a calibrated time base thould be obtained. The time
- with the report of welding and material defectsin accordance base and voltage values should be identified and recorded with the recommendation of regulatory position 2.a(3) of on the horizontaland verticalaxis of the above photographic Regniatory Guide 1.16, " Reporting of Operating Informa-record of the initial pulse. The method used in obtaining thm-Appendix A Technical Specifications."
the pulse shape photograph, inc!uding the test point at which it is obtained, should be documented.
C. REGULATORY POSITION
- 2. Call!! RATION Ultrasonic examination of reactor vessel welds should be i
performed according to the requirements of Section XI of System calibration should be checked to verify the DAC i
the ASME ll1PV Code, as referenced in the Safety. Analysis curve and the sweep range cabbration per nonmandatorf I
Report (SAR) and its amendments, supplemented by the Appendix B. Artic!c 4,Section V of the ASME Code, as a
- l luuowing:
minimum, before and after each RPV examination (or each week in which it is in use, whichever is less) or each time any.
l 1 INSTRUMENT PERFORM ANCE C11ECKS component (e.g., transducer, cable, connector, pulser, or receiver)in the examination system is changed. Wis:re possible, The checks described in paragraphs 1.2 through 1.5 >hould the same calibration block should be used for successive in-be made for any UT system used for the recording and sizing service examinations of the same RPV. The calibration side of reflectors in accorde.':e with regulatory position o and holes m the baste calibration block and the bluck surfaceshould fur reflectors that exceed the Code-allowabic criteria, be protected so that their charactertstics do not change during storage. These side holes or the block surface should not be modified in any way (e.g., by polishmg) between successive 1.1 Frequency of Checks examinattuns. If the block surface or the calibration retlector ho!cs have been polished by any chemical or mechanical means, As a minimtun, these ' checks should be verified within i day this fact shouhl be recorded.
hefore and within I day af ter cuminmg all the wlds that need to be examined in a reactor pre >>ure vessel during one outage, l'aise shape and noise suppresuon controls should remain at 2.! Calibration for Manual Scanning the same setting durmg examination and ca'ibration.
For manual scanning for the sizing of flaws, static calibra-1.2 Screen lleight 1.!ncarity tion may be used if sizing is' performed using a static trans-ducer When signals are maxid ized during calibration, they n
Screen height linearity of the ultrasonic instrument should also be maximized during sizing. For manual scanning
>bould be determined according to the mandatory Appen-for the detection of flaws, reference hole detection should be dn I to Arttele 4,Section V of the ASME Code, wittun the shown at scanning speeu and detection level set accordingly tune hmits specilied m regulatory position t.1.
(f rom the dynamic DAC).
2.2 Calibration for Mechanized Scanning
- d. When a universal calibration block is used and some or all of the reference holes are IgrgWthan.the retlector When llaw detection and sizing are to be done by holes at comparabic depths recommended by Article,4, Sec-much.mited equipment, the calibration should be performed tion V, of the ASME Code,1980 edition,a correctiort, factor using the followmg guidelines:
should be used to adjust the DAC level to compensate for the larger redector holes. Also, if tne reactor pressure vessel
- a. Calibration speed should be at or higher than' the has been previously examined by using a conventional block, scanning speed, a ratio between the OAC curves obtained from the two blocks should be noted (for reference) with the significah b..The direction of transducer movement during calibra-indications data.
tion sho'ild be the same as the direction dunng scanning m,. m ANDg48-"StJRFAGE unless(1) tt can be shown that the change in scanning direction
- 3. NEAR SURFACE : EXAMINATION does not make a difference in the sensitivity and vibration RESOLUTION.:
.- t u d u background noise received from the scarch unit or (2) these differences are taken into account by a correction factor.
The capability to effectively' detect defects near the front and back surfaces of the actual component should be A
,4
- c. For a mechanized
- scanning, signals should not be estimated.The results should be reported with the report of maximized dunng the establishment of the DAC curve.
abnormal degradation of reactor pressure boundary in accordance with the recommendation of regulatory posi-J. One of the following alternative' guidelines should be tion 2.a(3) of Regulatory Guide 1.16. In determining this followed for establishing the DAC curve; capability, the effect of the following factors should also bc l
' considered:
(1) The DAC cutve should be established using a moving transducer mounted on the mechanism that will be
- a. If an electronic gate is used, the time of start and stop u.ed for examination of the component.
of the control points of the c!cctronic gate shculd be
- related to the volume of material near each surface that is (2) Correction factors between dynamic and static not being examined, response should be established using full scale mockups.
Ip The decay time, in terms of metal path distance, of (3) Correction factors should be established using the initial pulse and of the pulse retlections at the front and models and taking sealing factors into consideration (assumed back surface should be considered, sealing relationship should be verified),
- c. The disturbance created by the clad weld metal I
(4) Correction factors between dynamic and statie interface with the parent metal at the front or the back response should be estabbshed from the indications that are surface should be related to the volume of material near the found during examination for staing. For detection of flaws interface that is not being examined.
dunng the initial scan, correction factors may be assumed based on engineering judgment. If assumed correction
- d. The disturbance created by front and back metal l
factors are used for detection, these factors should later be surface roughness should be related to the volume ot' l
confirmed on indications from Daws in the vesset during the material near each surface that is not being examined.
~
eumination. Deviation from the assumed value may suggest reexamining the data.
- 4. IlEAM PROFILE 2.3 Calibration Checks The beam profile should be determined if any recordable j
tlaws are detected. This should be done for each search unit l
If an EDS is used for calibration check, the following used durint, the examination by a procedure similar to that should apply:
outlined in the nonmandatory Appendix B(B 60), Article -1,Section V of the ASME Code,19:10 edition, for determining i
- a. The significant D AC percentage level used for the beam spread. Ueam profi!c curves should be determined for j
detection and sizir.g o
.dications should be reduced ta cach of the holes in the basic calibration block. Interpola-l take into account the nuximum error that could be introduced non may be used to obtain beam profi!c correction for assess-in the system by the variation of resinnce or leakage in ing Gaws at intermediate Jepths for which the beam profile l
the connectors or other causes.
has not Scen determined.
- b. C:.libration checks should be performed on the
- 5. SCANNING WdLD METAL INTERFACE complete connected system (e.g., transducer and cables i
t shuuld not be checked separate!y).
The beam ang!cs used to scan welds should be based on the geometry of the weld / parent metal interface. At least r
I c, Measures should be taken to ensure that the different one of these ang!cs should be such that the beam is almost variables such as temperature, vibration, and, hock limits
- )erpendicular (115 degrees to the perpendicular) to the l
for which the tills crror band is determbed are not exceeded weld / parent metal interface unless it can be demcnstrated l
during transport, use, storage, etc.
that untavorably oriented planar daws can be detected by
the UT technique being used. Otherwise, use of alternative the site for examination by the NRC staff. If the size of volumetric NDE techniques, as permitted by the ASME an indication, as determined in regulatory positions 6.1 or Code, should be constdered. Alternative NDE techniques 6.2, equals or exceeds the allowable limits of Section.X1 of may be considered to include high intensity radiography or the ASME Code, the indications should be reporteJ as i
tandem-probe. ultrasonic examination of the weld metal abnormal degradation of reactor pressure boundary in interface.
accordance with the recommendation of regulatory posi-tion.2.a(3) of Regulatory Guide 1.16.
6.- SIZING Along with the report of ultrasonic examination test *.
Indications from geometric sources need not be recorded, results, the following information should also be included:
6.1 Traveling Indications
- a. The best estimate of the error band in sizing the flaws and the basis for this estimate should be given.
Indications that travel on the horizontal baseline of the scope for. a distance ttreater than indications. from the
- b. The best estimate. of the portion of the. volume eahbration holes.(at 20 percent DAC amplitude) should be required to be examined by the ASME Code that has not recorded. Indications that travet should be recorded and been effectively examined such as volumes of material near '
siecd at 20 percent D AC Where the ir dication is sized at each surface because of near-field or other effects, volumes 20 percent DAC, this size may be corrected by subtracting near interfaces between cladding and parent metal, volumes tur the beam width in the. through-thickness direction shadowed by laminar material defects, volumes shadowed ubtamed from the cabbration hole (between 20 percent by part g:ometry, volumes inaccessible to the transducer, DAC points) that is at a depth simdar to the flaw depth. If volumes affected by electronic gating, and volumes near the the indication exceeds 50 percent DAC, the size should be
>uiface opposite the transduc' er 'O iecorded by measuring the distance between 50 percent DAC levels without 'using the beam-width correction. The
- c. The material volume that has not been effectively determined size should be the larger of the two.
examined by the use of the above procedures may be exammed by alternative effective volumetric NDE techniques.
6.2 Nuntraveling Indications if one of these alternative NDE techniques is a vanation of UT, recommendations of regulatory positions I and 3 Nontraveling indications above 20 percent DAC level should apply. A description of the tjehniques used should that persist for a scanning distance of more than 1 inch plus he includcJ in the report. If other votametric techniques or the beam spread between 20 percent DAC points (as variations of UT are used as indicated in regulatory po<i-defined by nonmandatory Appendix D, Article 4,Section V tion 5, the effectiveness of these techniques shonhl N uf the ASME Code,1977 edition) >hould be considered demonstrated and the procedures reported for review by significant. The site of these f!aws should be determined by the NRC staff.
measu ring the distance between points at 50 percent D AC and between points at 20 percent DAC where the beam-D. IMPLEMENTATION width correction is made only for the 20 percent DAC ute.
rhe recurded ute of the llaw would be the larger of the liteept in those cases in which an applicant proposes an two deternunations. If it can be adequately demonstrated acceptable alternative method for complytng with spec:fied that a nontraveling indication is from a geometric soure port:ons at the Commission's regulations, the method ynd not a flaw), there is no need to record that indication.
desertbed heretn will be used in the evaluation of (1) the results ofinservice examination programs of all operating The following information should also be recorded for teactors after July 15,1981, and (2) the results of pre.ervice indications that are repoitab!c according to this regulatory exainination programs of all reactors under construction position:
perf ormed after January 15,1982.
Indications should be recorded at scan intervals no The recommendations of this guide are not intended to a-greater than one-foutth inch, apply to prnemee examinations that have already been completed.
- b. The recorded mformation should include the indica.
tion travel (metal path length) and the transducer position The NRC staff intends to recommend that at! !icensees far 10 percent, 20 percent, 50 percent, and 100 percent modify the:r technical specifications to make them consistent t> AC and the manmum amplitude af the signal, with the recommendations contained herem.
- 7. REl>0RTING OF RESULTS t
Records obtained whi!c following the recommendations
- tt shou!J be noted that the McInsee fs reautred to apply for relief twn,n,prunca As'.tmae requirepienta ucurang to s 50.55. er of tegu!atory positions 1.2, 3, 5, and 6, along with Jiscus-
- U 1 U * * ' * " " " "" "" "
- J * " * " ' " ' * * * ! d *
- P ' ' *
- sloth.md explanations, if Jny, should be kept available at hopcotiun plan in l'ic plant Salt, n:e liccHsce a rc@treJ (O Ge an on ndant when the cuinnutu.cnts nidae in the S AR eannot be snet.
i
4 e
I.
J 9
VA LUE/ IMPACT STATEMENT I
1, Plt 0 POSED ACTION l.
demonstrated without doubt that the Gaw will not grow 1.1 Description and has not been growing, a ratherlarge flaw can be tolerate Crack initiation and growth is also a potential problem in The present inservice examination. procedures for cases where it is probable that no crack exists, but where ultrasonic examination require improvement in order to there is a cluster of small rounded inclus reliably characterize Qaws in reactor-of inclusions should be monitored by UT to ensure absen consistently and of cracks and crack growth.
pressure vessel (RPV) welds and RPV nonle welds. The app.irent low level of the reproducibility of detection, luc;ttion, and characterization of Qaws leads to lengthyWhere the rate of flaw growth is expected to be large o discuulons and ' delays. in the ' licensing process. hiuch is uncertain, even a small flaw may be of concern. To
,.ittpatiQn.ls paid to the integrity of RI'V welds during the permit determination.of growth rate, the UT procedures lic<nsing process because the failure probabdity of a reactor should be such that results of successive UT e pressure t venscl is considered to be sufficiently low to can be compared. With present procedures, these results
' exclyde,,1{,from consideration as a design basis accident cannot be compared because of variation in instrument The.. assumption of a low probability relies heavily on,system characteristics..UT instrument system characteristics regulatlya. repeated inservice examination by ultrasonic depend on the characteristics of the system's different testing (UT) of. welds.
components. Variation in the characteristics of calibration blocks can also affect results.
.w.. o.h mam.. w 1.2,.Need for l'roposed Action Guidelines are needed so that uncertainties
..n s,,o w,so, ala..a
, As mQre, reactors, start producing power, as those in terization may be reduced or eliminated. The safety of the
- a operationg grow q! der,, and,as more inservice examinations components is evaluated with the help of fracture mechanics,
)
arc performed, the number:of detected Daws with uncertainflaw sizes need to be known for fracture mech characteristics (sue, orier;tationa and location) is likely to tions. Uncertain determination of daw sizesleads t icercap,, f. law charactenzation is essential for flaw evalua.
taintiesin the determination of the safety of the components (iuns, required by the AShlE Code anl.1 by NRC to determiUncertainties in component safety Isad to delays in lic the structuralintegrity of nucicaricactor components witenThere is a need to specify and stanl'lardize the performanc ne such Haws exist. It is essential to have valid backgroundsequired of most UT system components to achieve better data for the flaw evaluations required by Section XI of the consistency in UT results so th st delays in the licensing AShili Code, liased on the information gathered according process may be reduced.
to AShlE,Qode requirements,it is often difficult to assess whether.,or.not,the Oaw has grown between examinations.
This guide will provide supplementary procedures with The. procedures,now in use.do not require the recording of the objective of improvmg conventional UT procedures
,,t s cuitauginformation that can be important.m later analysts defined in the AShtE CodeaThis guide is based partly on the for, determining the location, dimensions,, orientation, and information available in literature concerning both U S and growth ruc of Daws,.,w.,
an lluropean procedures and partly on the judgment of the
..,,,.r.,..
.q. a,a:.t.nr. st.,u.i t e,. nm w.d on NRC staf f and their consultants. On the basis of support vah. n u.
Thq. lack,of standardization in.thesse of UT equipmentwork being performed at.the Oak Ridge National Lab' orat n
and pr9eedures leads to,uncertataty concerning the. resultsthe staff plans to issucia revision to this guide th.it should
(
obtaineda For,cxample, transducer characteristics such as further improve Oaw characterization..
{
beam
- H "r"'"au spread, damping characteristics,. and. frequency m. n..."
%.ti #. adhi A for peak response are not defined, and there is no provision The use of new techniques such as holography or sy~nthe to keep track of these from one examination to the other.aperture imaging.of flaws by.UT that have not been imple-Similarly,; characteristics of.other UT. system components munted into practice and could considerably. increase the t
l such as the pulser,, receiver, amplifier, and video display cost of inservice examination is not beingiproposed here.
screen may, vary from one examination to another, and all these characteristics }an inDuunce the magnitude of the 1.3 Value/ Impact of Proposed Action o a od.. d I tiaw indications.,Therefore, well defined cnteria for supple-d "t' mentary UT. procedures are needed so that it wdl be possible L3.1 NRC to.currectly, c,haractenze flaws,. estimate Oaw growth and a.
J so ' d 5
l have i
reproducible results from.mspections performed at Reporting UT examination results as indicated in'this guide thiterent times using different equiprnent, would help the.NRC: staff ind' their consultants to better g
assess the results of the datae. At present,"the NRC staff
,.ai7.w :
.n..
.. i, In,.many,itutances, the rate of Daw growth,can be even must spend a great deal of time on. controversy over deter-more imp, ort,utt than the Oaw sue, For example, if a Gaw is mining the safety of components from inconsistent results.
UT lound, m,m, Rl'V, nozz!c,ur belt-line region and it can b Lack of faith. in. flaw: size s determination from l
e uncertain UT results, points toward the adoption of some uti,
1a.,,b...
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,.n nu..n o, o, ih noi.
I
conservative safety measures that are undesirable, for the
- i. Providing more consistent UT procedures for flaw most part, to the industry managers. Licensing delays occur chcracterization, thereby leading to procedures that because decisions have to be made on the basis of uncertain ensure lower probability of missing large Gaws and mformation. !? law size determination from consistent UT ensuring greater safety for the pu blic, in[lus{ rial results would help remove or reduce the uncertainties and workers, and government employees.
debates over the safety issues, llecause of the above, NRC staff. time for review of reported data and interpretation of 3
indications is likely to be reduced.
l.J.J.J /mpact. There will be majvr impact in the followind three areas; i
1.3.2 Ot/ser Covernment Agencies
- a. Quality control of he UT equipment Not applicable, unicas the government agency is an At present, requi cientsin the ASME Code for quality applicant, such as TVA.
control of UT. luipment are marginal; for example, there are no direct requirements to control the quality t,
.i.o i
of UT transducers. Criterion XII,"Controlof Measuring 1,J,3 ' /ndustry ;
and Test Equipment," of Appendix ll," Quality Assur-ance Criteria for.Nuc'. ear Power Plants and Fuel Repro-The value/ impact on industry of the regulatory guide cessing Plants," to 10 C!?R Part 50 requires,in part, that positions is stated by each positio'n in the appendix to this measures be established to ensure that instruments used value/ impact statement. Some highlights of the value and in activities affecting quality are properly controlled, impact of the regulatory guide positions are stated below.
calibrated, and adjusted at specified periods to maintain accuracy within necessan limits.The recommendations of this guide will help to bring about uniformity in the 1.3.J.1 Vahee. 'lhis regulatory guide specifies supplemen-quality control procedures among different companies tary procedures that will lead to the following advantages:
and will ensure that quality control measures are taken to ensure reliability and reproducibility of UT results.
a.. Attaining greater accuracy and consistency in Gaw No new UT equipment will be needed to follow the characterization.
recommendations of this guide. Ilowever, the quality control measures recommended for UT. equipment b, Providing information for consistent Oaw characteriza-will impose extra cost burdens that are difficult to tion at NRC review time und thus reducing NRC staff estimate without feedback from industry, effort in review of Qaw indications.
- b. Increase ih examination time
- c. IIciping assess daw growth.
This guide would recommend, for the first time, tnjit
- d. Providing a more reliable basis for Qaw detection and indications with significadt length of indication travel, evaluation, which should help in the uniform enforce-(larger than the standard calibration holes) or with ment of rules and the avoidance of delay in licensing significant depth dimensions be recorded, it is not decisions, expected that the slag type of Daws, which are common O
among wc!ds, or geometric re0ccrors will give signif-
- e. Reducing licensing time for reviewing examination icant traveling indications within the guidelines pro-results, which wi!! aid in the reduction of reactor down-pused. Ifence, no substantial increase in recorded time during examinations and will be of great benefit indications as a result of this recommendation is to industry. With present construction costs of about expected; however, the exact increase is difficult to 1.3 bdlion dollars for a 1000-megawatt reactor and the predict or estimate; average size of a reactor running around 1100-megawatt capacity, t!te savings per day by eliminating reactor Reporting of indications associated with Daws larger downtime are likely to be $500,000 or more.
than I inch (indications larger than 1 inch plus beam spread at 20 percent DAC leve!)is also new. RPV welds
- f. Avoiding unnecessary repairs due to daw size uncer-are examined by radiography, and no Gaws targer (nan
- tainties, three-quarters of an inch are acceptable m these welds.
Because of this acceptance length, only new service-
- g. Reduemg radianon exposure to personnel by helping mduced daws larger than 1 inch, of which there should to climinate unnecessary re pairs. The radiation not be truny, are expected to be identified and reported exposure during repairs is usually many times the as a result of this recornmendation.
exposure during exanunation, su a net reduction in radiation exposure is cxpected.
Because of the above tho new reporting recommenda-tions, there may be an increase in examination time
- h. Reducing margms of errorin estimates of flaw growth and dol!ar cost that is difficult to estimate. This wd!
and thus helping reduce overconservative estimates depend on how many significant flaws are detected and decisions un daw acceptance.
and how large and complex they are.
1 c, Radiation exposure 2.3 Comparison of Technical Alternatives Recommendations of this guide apply to the examine-Imposing inservice examination of RPV welds by the use Lion of RPV welds and RPV nozue welds. RPV welds of holography, synthetic aperture imaging technique, or I
fare usually examined by automated equipment, and acoustic eminion, all of which are still in the stage of proto-data are collected on tape. Therefore, no increase in type development and have not been proved effective for radiation exposure is anticipated as a result of the field use, would not be justifiable on the basis of either.
, regulatory guide ' positions addressing. RPV weld cos! or effectiveness.
ex aminatio'ns, si 2.4 Comparison of Procedural Alternatives llPV ' nozz!c welds are sometimes examined by
, automated equipment but in most cases by manual UT, An increase in radiation exposure to examination Leaving the situation as it is would mean that continued
. person'nel may be expected while RPV nozzles are attention and manpower would have to be devoted by the being, manually examined, 'The probable percent NRC staff to investigate the uncertaintics associated with
[ increase in examination time or radiation exposure is flaw growth on a case by-case basis. The lovt level of
' mpossible to. estimate without field data and research confidence in the present techniques means that excessive -
i effort, Requirements for reporting traveling indica-margins would continue to be used in the flaw-acceptance tions and indications associated with Daws larger than criteria. Also, unnecessary cutting and repair attempts to Iinch may ! cad to an increase in occupational remove suspected Daws may result, exposure in those cases in which the above indications are found and additional examination is required. The The procedures recommended-in this guide have been magnitude of this additional exposure can only be shown to be effective in practice, at: hough they are not in auessed on a case by case basis. It should be noted general use in the United States. Including these procedures that radiation levels at venel nozz!c regions are as regulatory guide recommendations should result in their.
reported to range from 0.5 to 2.0 rem / hour. Total wider use and consequently their improvement. After these person rem doses can be drastically reduced by procedures have been accepted by the industry, we wdl shielding and local decontamination.
seek their inclusion in the ASME Code. Some of these procedures have already been sent to the ASME for consideia-The guide is not expected to have any adverse impact on tion and inclusion in the present. ASME Code procedures other government agencies or the public, for ultrasonic examinations.
1,3.4 Pubtfc 2.5 Decision on Technical and Procedural Alternatives No impact on the public can be foreseen. The only identifiable value is a slight acceleration in the review On the basis of the above, it appears desirable to iss'ue a proecss.
regulatory guide to provide recommendations for improving ASME Code procedures. These recommendations, whidh I.4 Decision on Proposed Ac' tion are based on the advanced st3ite-of-the art UT procedures in cu rrent use by some organizations, would improve the
'The, Office of Nuc! car Reactor Regulation (NRR) has abdity to detect and characterize Gaws without imposing stated the need for t!us guide to help them and their new, unproved techniques for flaw detection on industry.
consultants in evaluatmg the size and significance of the Daws detected dunng inservice examination to ensure the
- 3. STATUTORY CONSIDER ATIONS integnty of reactor pressure vessels between periods of examination. It would therefore be advisable to issue this 3.1 NRC Authority,
i guine.
The authority for this guide is derived from the safety
- 2. apt'ROACll requirements of the Atomic Energy Act of 1954, as amended, and the linergy Reorganization Act of 1974, asimplemented 2.1 Technical Alternatives by the Conunission's regulations. In particular, @ 50.55a,
" Codes and Standards, of 10 CFR Part 50 requires, m Alternatives would include requiring the use of holography, part, that structures, systems, and components be designed, l
synthetic a pe rture imaging, acoustic emtssion, neutron fabricated, erected, constructed, tested, and inspected to tadiography, or a combination of the above during RPV quahty standards commensurate with the importance of inservice eumination.
the safety function to be gerformed.
2.2 Procedural Alternatives 3.2 Need for NEPA Assess
- ment t
One alternative is to Icave the situation as it is. A second The proposed action is not a rnajor action, as defined by alternative is to request change of the ASMR Code require-paragraph 51.5(a)(10) of 10 CFR and does not require an
- ments, environmental impact statement.
g e
e
-1. RE!.ATIONSillP TO OTl!ER EXISTING Oft PRO.
difficult for the NRC staff or their consultants to review, POSED ltECULATIONS Oft POLICIES analyze, and assess the UT data to determine the flaw size and evaluate the system safety when the data are made
> Recommendations of this guide would be supplemental available to NRC at a later date. The present data obtainctf, to the. requirements of Section XI, " Rules for Inservice from UT equipment of uncertain and unspecified performance Inspection of' Nuclear Power Plant Components," of the
' lead to discussions and delays in the review process resulting ASME Code, which is adopted by Q 50.55a, " Codes and in loss of NRC staff time and loss of plant availability Standards," of 10 CI R Part 50.
and power generation capacity for the utilities. Thesc situations definitely need to be avoided as much as possible.
- 5.
SUMMARY
This guide is aimed at achieving this purpose by issuing recommendations that will be supplementary to the existing This' guide was initiated as a result of a request from ASME Code UT procedures. The issue remains whether to NRR. Preliminary results of the round robin UT examination wait for the development of advanced NDE techniques and procedures following ASME Code procedures indicate a continue with the present ASME Code procedures resulting need for additional guidelines to the existing ASME Code in uncertainties, delays, and discussions or to encourage proceduresito control equipment performance, calibration improvement in the present state of the art of conventional i
block specifications, and scanning procedures to improve the UT. The decision appears to be obvious that we should use ieproducibt!(ty of results und detectability of through thick-convuntional UT based on engineeringjudgment until some ocas llaws.
new techniques for flaw detection and sizing can be proved effective in the field. This guide is aimed at providing the 1
Minimum ASME Code requirements do not specify the recommendations needed to improve on the ASME Ccde details of recording requirements that are essential to UT requirements until proven advanced NDE techniques evaluate flaws. This deficiency in the Code rules makes it are available.
.E 9
a 9
4 g
i I
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APPENDIX TO VALUE/ IMPACT STATEMENT
.a i Values that will result' from this regulatory guide are now apply to the examination of the RPV, require calibra-much easier to perceive than the impact. It is very difficult tion against the calibration block only " prior to use of the to assess the real impact because the kind of statistical data system." It is considered that the present 1977 ASME Code needed is simply not avadable at this time.One way in which rules are not adequate to control potential prob! cms in the we hope to estimate the impact is through industry feed-variation of instrument performance characteristics. There.
back after the guide has been issued, fore, the recommended calibration before and after each examination is a more reliable approach to instrument We 'have made an attempt,.in a qualitative manner, to performance checks. The above position is not more con-estimate ithe value/ impact of regulatory guide positions, servative than the previously accepted 1974 Code rules, butis
. position by position, as follows:
more conservative if 1977 rules are considered.,
y a
I, INSTRUMENT PERFORMANCE CllECKS Considering the requirements of Article 4,Section V t
(1977), the above position will mean a calibration check Recording the characteristics of the ultrasonic testing each week the system is in use or before and after each (UT) examination system will be usefulin later analysis for RPV examination, whichever is less, instead of before cach determinirig the location, dimensions, orientation, and examination. A calibration check against the calibration growth rate of flaws. System performance checks to deter-block takes 15 to 30 minutes. for manual UT and for mine the charactenstics of the UT system will be made automated UT equipment where provision is made to shortly before the IJr examinations. Each UT exammation calibrate the equipment without having to remove the trans-will therefore be correlated with a particular system per-ducers from the rotating scanning arm of the mechanized, formance check. This practice will help to compare results.
scanner. In some cases, transducers have to be removed These determinations will help make it possde to judge from the scanning arm for cahbration of the UT instrument; whether differences in observations made at different times in these cases, a calibration check may take from 30 to 60 are due to changes in instrument characteristics or are due minutes. The added cost of the above wuuld be in terms of to real changes in the flaw size and characteristics, additional time spent by the exarniner and would occur each week or once for each RPV examination, depending it
- is recommended that, as a minimum, instrument on whether or not the examination is completed in lea checks should be verified before and after examining all the than a week. No additional radiation exposure is expected welds that need to be examined in a reactor pressure vessel because of this position.
during one outage.
- 3. NEAR SURFACE EXAMINATION AND SURFACE Performance of these instrument checks is Iikely to add RESOLUTION a few thousand dollars to test equipment cost and to take 1 to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of examination time before and after each reactor This position recommends that an estimation of the pressure vessel (RPV) examination. The examination equip-capabdity to effectively detect defects at the metal front ment is usually idle between examinations. Performance and back surfaces of the actual component should be made checks on the examination equipment could be performed and reported. This will not require any additionalcalibration during these idle periods. These performance checks are not or exantination time but will simply require an estimate of bkely to reduce the number of examinations that a particular this capability by the examiner, which will be reported to UT system could perform in a year. No additionalradiation NRC. No additional radiation exposure is expected because ex posure is expected because of this position, of this position.
- 2. CAL!!! RATION 4.11EAM PROFILE According to this position, system calibration should be This position recommends that the beam profile (for checked to verify the distance-amplitude correction (D AC) each search unit used) should be determmed if any signif-curve, as a minimum, before and after each RPV examina-icant I' laws are detected during the RPV exanunation.
(
tion (or each week the system is in use, whichever is Icss) or
- ach tirne any component (e.g., transducer, cable, connector, Assuming that no more than three search units are likely i
r her, or receiver) in the examination system is changed.
to be used durmg an RPV examination, this step is likely to u
require no more than 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of examination time. No Subartic!c l-4230, Appendix I,Section XI, ASME 3&PV additional radiation ex)osure is expected because of Code (1974 edition), wtuch applied to the inspection of the this position.
t l
l RPV, required calibration using the basic calibration block at "the start and finish of each examination, with any change
- 5. SCANNING WELD METAL INTERFACE i
in cumination personnel and at ! cast every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> during an examination." !!uwever, the 1977 rules of Article 4 Tlus position recommends that the beam angles used to j
(T LlJ),Section V, which are referenced by Section XI and sean welds should be based on weld / parent metal interface i
1 a ** ~
i:cometry and at least one of these ang!cs should be such that on the screen larger than the indication on the screen from the beam is almost perpendicular (:tl5 degrees to the perpen-the calibration holes (1/2-inch hole for a 12-inch weld dieular) to the weld / parent metal interface, unless it can be thickness, 3/8-inch hole for an 8-inch thick.ncss), t!}is
}
demonstrated,that large (Code unacceptable) planar Gaws recommendation will not result in any more recording of ontavurably oriented can be detected by the UT technique.
indications. If the RPV welds being examined have several indications with travel in excess of the calibration hole On the basis ofinformation available,it appears that it is diameter, the examination and recording time will be j
difficult,2) to detect large planar tlaws(e.g., service induced increased for the investigation of these flaws, depending a
fatigue or stress corrosion cracks) oriented at right angles to on the number of these indications. Slag inclusions in welds i
the surface, using the ASMli Code UT procedure. However,
. are generally long cylindrical defects and do not uave much the option is being provided to demonstrate that such flaws depth unless they are associated with shrinkage or service-4 can be located by conventional methods or by using new induced cracks. These slag inclusions are not expected to advances m UT techniques. In these cases,the technique will increase the number of indications that will be recorded.
l 14 acceptable as a volumetric examination method. Otherwise, increase in examination time will depend on the number, the use of high intensity radiography or tandem probe UT siec, and complexity of geometry of through thickness technique, among other techniques, should be considered.
indications.
The above type of flaw is the most significant but the For RPV girth or nozzle welds where examination is must difficult to detect.13ceause of this, the present recom-performed by automated equipment and data are recorded i
mendations are being made despite their potential impact on tape, this position will mean no increase in examination on enst and radiation exposure.
time or radianon exposure; but interpretation, analysis, and reporting time for these depth indications will increase. The
~
The potential impact may be as fo!!ows:
extra burden in terms of dollar cost w0l depend on the number, size, and complexity of flaws, and there are no
- a. ~ Additional NRC staff time may be needed to evaluate rational bases or data availaW at this time to estimate the the effectiveness of UT techniques on a gener;c basis to increase in the cost of examination.
j detect perpendicular planar flaws..*,fter techniques are recognized to accomplish the above, NRC staff time that is For RPV welds, mostly nozz!e welds, where examination being spent currently on evaluating problems on a plant by-is performed manually and data are not recorded on tape, p' ant basis is expected to be considerably reduced.
this posiiion will mean extra cxamination time and increased radiation exposure to the examiners. Increase in dollar cost i
- h. Reactor downtime may increase, depending on the and radiation exposure will again depend on the number, examination time differentials between the conventional size, and complexity of indications, and there are no bases md retined techniques. This may, however, be offset by a or data available to estimate this increase.
j reduction in the downtime currently needed for NRC i
{
]
esperts to evaluate data that sometimes requires further 6.2 Nontraveling Indications etasification and reexamination.2s This poshion also recomraends the recording of nontravel-
- c. Additional cost might be incurred in changes needed ing indications above 20 percent DAC level that persist for to add transducers or data-gathering capability to existing a distance of more than 1 inch plus the beam spread.
automated equipment or to automate current manual According to ND 5320, Radiographic Acceptance Standards, examinations. Automation of current manual techniques is Section Ill, Division I, ASME Code,1977 edition, flaws hkely to reduce radiauon exposure to personnel, larger than 3/4 inch for we!d thicknesses above 21/4 inches are not accepta ble. Because of this requirement, it is
- 6. $121NC AND ltECORDING OF INDICATIONS expected that no llaws larger than 3/4 inch in length are present in the RPV welds, and if indications are detected 6.1 Traveling Indications that suggest flaws larger than 3/4 inch, there is a strong i
possibihty that these may be service induced flaws. Service-This position recommends the recording of traveling induced flaws are rare in RPV welds, and it is therefore indications. If RPV welds do not have any travelindications not expected that additional indications would have to be recorded because of this posttion. Ilowever, it such indica-
,"Prababihty or Descenng Planar Durccia in Heavy Walt Weldt by tions (over ! inch) are detected, examination time for uur.w.us Tsannous Ascurding to Esiinne codes." or. tag. Hans.
automated recording and examination time plus radiation Jp. tun wyer, Qu.hry Department or u.A.N., Nurnberg, o usou won.cg i t s.
exposure for manual UT exammations will. be increased.
There are no rational bases or data available to estimate the 2"bassiin Tech'nicat Report on UWtt FeeJwater and Control Rod Dove Resum 1.ms Nouta Lracinng,"NUREG-0312. July 1977, p. 3.
impact of regulatory position 6.1 3 analysis or in. Uttr. onic Ex.minadon of Pvnc weia speci-
- 7. REPORTING OF RESULTS *
.na.
i s s 202, and 203," tt.A. uuchanan. Preuure Vcssel Research Cunnnotes (l'VRC) Report. Augua 1970.
t This position recommends that the areas required to be 4 "sununary or the Deiccoon and Cniuanun or U
- u. us. 4.dwin If.ush Unit i itsassur Preuur Vessel,,i,trasonic indica-January 1972.
exanoned by the ASME Code that have not been effectively
.....r cu, Puu r com pao r.
exammed and an estimate of error band m sizmg the flaws
. - -. _, _ _._-__-- _ _. _,.__._,_-._.__ _ __._..._____ _. _, _ _. _ _. _..._._____..____. _ _ _ _,, -. _ _ _ _ _ ~
e s should be brought to the attention of the NRC when the of this guide, those inservice and preservice examinations results are reported. This effort may take about $ hours in performed in the past. Such a policy would tend to be seportwriting time, overly conservative and would ptt a heavy burden,on all plant owners. Although UT exarninations have misseq some
- 8. IMpt.EMENTATION flaws in the past, there appears to be no immediate danger from the estimated flaw distribution probabdity to warrant it should be noted tha't the recommendationsof this guide such a strong actinn. Therefore, this alternative was not are not intended to apply to those preservice examination
- adopted, tests already completed. Ilowever, the licensees may consider repeating their preservice examination tes's or.
3.2.2 Second Alternative using the recommendations of this guide any time at their' option to avoid possible Gaw interpretation problems at a In the past, several instances have been noted where the
, later date. Flaw interpretation problems may occur if minimal Code UT examination procedures have not been traveling indications identified as significant according to adequate for detecting and sizing flaws. Discussions and the recommendations of this guide do not correlate with undesirable licensing delays were frequently the result. As paeservice volumetric NDE results and hence would be more plants begin producing power and existing plants grow a.sumed to have been service induced. It would be difficult older, moic naws may be exnected in the weld areas. These in show that these indications arose from fabrication flaws.
flaws may be generated as a result of fatigue, stress corrosion,
't hetsfore, licensees would be well advised to consider the or uther unanticipated factors. it is imperative that 'the above possibilities.
guide recommendations for supplementary UT examination procedures be used in the future to maintain an acceptable 8.1 Alternatives level of safety at thesc.we!ds..The second alternative was therefore selected for applying this guide to the preservice The following alternatives were considered in applying and inservice examination of RPV welds.
the recommendations of this guide.
it is expected that insenice UT examinations will detect I. To apply the recommendations of the guide to all the flaws generated dunng plant operation, whereas preservice preservice and inservice examinations that have examinations will provide UT examination data for sub-already been performed.
sequent comparisons. First, a radiographic examination is performed of all the vessel welds under Section lit of the
- 2. To apply the recommendations of the guide to all ASME Code. After this examination, a UT preservice exam-future preservice imd inservice examinations per-ination of welds is performed to serve as a supplement.ny formed after the issuance of the guide, volumetric examination. Because of the above, these pre-service examinations are not as important as inservice exam-N.2 Discussion of Alternatives inutions. it was therefore decided that the guide reconunend,a-ttons shou!Al apply tojudgtng the inservice examination results 3.2,1 Arzt Alternative for those examinations performed immediately after t!']c issuance of the guide; however, the guide recommendations Alternative I would infer that all RPV welds examined should apply to preservice examinations beginning 6 months as per the current code requirements are at a quality level after the issuance date. The NRC staff considered this that would not ensure an acceptab!c safety pertbrmance.
approach best because of the difficulties being experienced
't his approach would also mean that all the plants would in reviewing inservice UT examination data from the have to repeat, m accordance with the recommendations different plants.
I t
t t
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