ML20079F936
| ML20079F936 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 09/27/1991 |
| From: | Feigenbaum T PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | Martin T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NYN-91157, NUDOCS 9110080331 | |
| Download: ML20079F936 (29) | |
Text
4 s . . . ,
9, ' c' New Hampshire Y k Ted C. Feigenbaum President and Cniel Executwe Othcer l
l I
NYN 91157 i September 27, 1991 United Statcs Nuclear Regulatory Commission
, Region 1 475 Allendale Roaa King of Prussia, PA 19406 Attention: Mr. Thomas T. Martin, Regional Administrator
References:
(a) Fac lity Operating I.icense No, NPF-86, Docket No. 50 443 (b) NIIY 1.etter NYN-91142 dated September 6, 1991, " Pullman-liiggins Weld Radiograph Reinterpretation Program," T. C. Feigenbaum to NRC Document Control Desk (c) NilY Letter NYN 91151 dated September 17,1991, " Additional Reply to Notic: of Violation (NRC Inspection Report 50-443/91-12) and Radiograph Reinterpretation Program Completion R e po r t," T, C.
Feigenbaum to T. T, Martin (d) NRC Letter dated September 24, 1991, " Review of Radiograph Reinterpretation Program Coinpletion Report and of the Reply to an NRC Notice of Violation," T. T. Martin to T. C. Feigenbaum S ubject: Supplemental Submittal for the Radiograph Reinterpretation Program Completion Report
Dear Mr. Martin:
The NRC letter dated September 24,1991 [ Reference (d)] requested New llampshire Yankee's (NilY) response to three questions, tinelosure 1 to this lettes provides NilY's response to the three quesiions. Enclosures 2 and 3 to this letter transmit additional information and errata to the NilY letters dated September 17,1991 (NYN 91151) [ Reference (c)], which .ransmitted tae results of implementing the Weld Radiograph Reinterpretation Program (WRRiP) and September 6, 1991 (NYN-91142) l Reference (b)], which transmitted the WRRIP description.
l This letter transmits the justification for NilY's determination that the WRRIP results I
and corrective actions were conclusive in fully bounding, examining and resolving any generic implications regarding radiography at Seabrook Station. In the letter dated September 6, 1991 (NYN-91142) [ Reference (b)], NHY provided the results of a detailed evaltation of such generic implications and submitted a Program Description for the Reinterpretation of Pullman-liiggins Field Weld Radiographs. In the I::tter dated, Sentember 10, 1991 the NRC found this Program neuptable.
9110080331 910927 POR ADOCK 05000443 P PDR {
I C U V .L d i ' New Hampsfure Yankee Division of Public Service Company of New Hampshire l P.O. Box 300
- Seabrook, NH 03874
- Telephone (603) 474 9521
i ,
United' States Nuclear Regulatory Commission September 27, 1991 i
Attention: Mr. Thomas T. h1artin Page two NRC Inspection Report 50 443/91-12 identified six radiegraphs that the NRC found not to meet ASME film quality requirements. NRC Inspection 50-443/91-21 found one additional radiograph which also Jid not meet ASME film quality requirements. The subsequent NilY WRRIP identified forty-seven weld radiograph package that did not conservatively demonstrate strict compliance with all film quality requirements prescribed by the Code. These combined reviews identified a total of fifty-four weld radiograph sets found to require re-radiography because of noncompliance with the ASME Code. NilY analysis of these radiographs led to the identification of the root causes for these Code non-compliances. The vast majority of these welds involved density concerns where small bore, piping was originally radiographed using a difficult double wall exposure, double wall viewing, source side penetrameter technique. This technique was unique in that no station markers were used at the outer boundaries of the area of interest. This introduced greater subjectivity and required more interpretive skills when evaluating the outer edges of the weld.
This unique set of circumstances was particularly exacerbated in three inch, heavy wall piping. This configuration resulted in a gradual transition of film density at the extremes of the area of interest. In retrospect, the extent to which densitometer readings were taken over the area of interest was insufficien' for this extremely difficult technique. The uniqueness of this set of conditions limited this difficult interpretation to an identifiable set of welds. For all other techniques used at Seabrook Station, station markers delineated the boundaries of the weld areas to be evaluated. NHY concludes that the extent to which densitometer readings were taken for this difficult technique is the root cause of the interpretive difficulties for the above forty-five welds.
The remaining welds were identified by others as not being in full compliance with ASME film quality requirements for radiographic sensitivity. NrY has evaluated the sensitivity concerns for these radiographs and concluded that the original Pullman-Higgins and YAEC reviews were correct in their determinations that the radiographs were acceptable per th( Code. The WRRIP was specifically designed to be conservative to climinate the potential for further questions and concerns regarding welds and their radiographs at Seabrook Station. Therefore, the radiographic packages with sensitivity concerns were rejected since, after close scrutiny, it was determined by multiple reviewers that these weld radiographic packages exhibited marginal, but acceptable required sensitivity.
NHY reviewed the entire population of potentially suspect welds radiograph packages (less those weld radiograph packages previously reviewed and accepted by the NRC). All radiographs found to contain inadequacies have been reradiographed and found to be in full compliance with the Code. NHY also reviewed radiographs taken with other techniques and, with no exceptions, found them to be in full compliance with the Code.
Based on the root cause analysis, confirmatory boundin3 analysis and completed corrective actions NHY concluded that there were no remaining unresolved film quality concerns for field welds requiring radiography by Code. NHY further concluded that any generic implications were fully bounded, examined and resolved.
- : 6-i- . i 4* .p i . .
. United States Nuclear Regulatory Commission September 27, 1991
_Atte ntion: Mr.-Thomas T. Martin Page three d
Should _ you have any questions regarding this matter, please c(Wir. Neal A.
Pillsbury, Director of Quality Programs, at (603) 474-9521, extensi 4341.
}
Very yours, s m n,4PD '
- - Ted C. Feih44am '
- Enclosure TCF:EWD/act/ss cci leu Gordon E, Edison, Sr. Project Manager Mr. Noel Dudley Project Directorate 13 NRC Senior Resident inspector Division of Reactor Projects P.O. Box 1149
- U.S.- Nucl_ ear Regulatory Commission- Seabrook, NH 03874 Washinghon, DC 20555 Mr. Ebe C. McCabe, Chief
- . - Reactor _ Projects Section U.S. Nuclear Regulatory Commission l- Region 1 475 Allendale Road King of Prussia, PA '19406 Document Control Desk
' United States Nuclear Regulatory Commission Washington, DC 20555 4
- - Mr. William Bateman Regional Operations Staff Chief.
i Office of the Executive Director for Operations l
U.S. Nuclear Regulatory-Commission 11555 Rockville Pike-Rockvillef, MD 20852 i-
.Mr. Phil Joukoff U.S. Nuclear Regulatory Commission
_1450 Maria Lane, Suite 210 Walnut Creek, CA 94596
[. /. Mr. Frank Forgione, Special Agent Office of the Inspector General U.S. Nuclear- Regulatory Commission MNBB 6715
-Washington, DC 20555
._}=_ $'
-y ..:
New Hampshire Yankee September 27, 1991 i
l l
l
)
ENCI.OSURE 1 TO NYN-91157 SUPPLEMENTAL SUBMITTAL FOR 'THE !! ADIOGR APH REINTERPRETATION PROGR AM COMPLETION REPORT 7
l l'
l l
l l
l
[
i
i RESPONSE TO NRC I.ETTliR DATED SEPTEMBER 24. 1991 A. Backcround in the letter dated September 17,1991 (NYN 91151), NilY provided the results of the Weld Radiograph Reinterpretation Program (WRRip). The results of this reinterpretation program concluded snat 100 percent of the physical welds reviewed had no rejectable indications, and, therefore, the subject welds were acceptable per the ASME Code. The reinterpretation effort .dso recognized that while the subject radiographs generally met the intent of the Code, 47 of tl.e 90 Pdiman Higgins field weld radiograph packages did not conservatively demonstrate stret compliance with all film quality requirements prescribed by the Code. NHY subsequently rcradiographed the 47 welds regardless of the nature or degree of the film quality concerns, and the .esults substantiate and confirm that the phyr.ical welds were in compliance with the Code. __
in the letter dated September 24, 1991, the NRC requested that NilY provide answers to three questions. The following provides the specific questions and NilY's responses.
B. Question Number 1
" Fifty-four weld radiograph sets were found to require re-radiography because of noncompliance with the ASME code. Multiple layers of film review during construction, including the 100% Yankee Atomic Electric Company review, did not identify this problem. What root cause or causes has or have been identified? llave generie implications bt.. i evaluated? If so, with what results? Please explain, as soon as practicable, the justification for the conclusion that the radiograph reinterpretation program should be concluded despite the 54 radiograph packages inadequacies missed during construction."
Summary Resoonse to Question Number 1
~
- 1. NHY identified the root cause of the radiograph non compliance with Code as a ~
shortcoming in the original radiographic interpretation process that is specifically limited to a single radiographic technioue. The technique involved is the double wall '
exposure, double wall viewing, source side penetrameter technique, when it is applied to three (3) inch nominal pipe sue welds where the initial Pullman Higgins review occurred prior to Octobe- 1,1982.
- 2. NHY reviewed the entire population of potentially suspect weld radiograph packages (less those weld radiograrh packages previously reviewed and accepted by the NRC).
All radiographs found to contain inadequacies have been rcradiographed and found to be in full compliance with the Code.
- 3. NHY reviewed radiographs taken with other techniques and, with no exceptions, found them to be acceptable and in full compliance with the Code. Based on the t c.a t cause analysis, confirmatory bounding analysis and completed corrective actions, NHY concluded that there were no remaining unresolved film quality concerns for field welds requiring radiography by Code. NiiY further concluded that any generic implications were fully bounded, examined and resolved.
1
The WRRIP identified a total of 47 weld radiograph packages that did not conservatively demonstrate strict compliance with all film quality requirements prescribed by the Code. As provided in the licilier Report #91912F, Revision 1, which was attached to the NilY letter dated September 17, 1991 (NYN 91:51), forty-four (44) of the 47 weld radiograph packages were identified primarily due to density concerns. Three (3) others were identified due solely to sensitivity concerns' NilY concluded that for 44 of the 47 weld radiograph packages, the original Pullman-Higgins and YAEC reviewers were in error in their determination that these radiographs were acceptable per the Code. This is a technique specific shortcoming regarding the extent to which density readings were taken at the outer fringes of the weld area of interest on the radiograph. NilY also concluded that for three (3) of the weld radiograph packages, the original Pullman-liiggins and YAEC reviews were correct in their determinatbns that the radiographs were acceptable per the Code. The bases for these conclusions are presen'ed in Section B.I.
The Notice of Violation from inspection Report 50-443/91-12 addressed a total of six (6) weld radiograph packages. A seventh radiograph package was subuquently added to the Notice of Violation as a result of NRC Inspection 91-21. As providnd in NilY's response to the Notice of Violation, dated July 8,1991 (NYN-91106), NilY cisputed the violation regarding the six (6) weld radiograph package concerns that were identified at that time. Notwithstanding the fact that these welds have since been retadiographed, NilY still concludes that these six (o) weld radiographic packages are acceptable per the Code, and therefore, that the original Pullman Higgins and YAEC determinations regarding Code acceptability were correct. A discussion of these six weld radiograph concerns and ac bascs for NHY's conclusions are presented in Section B.I. The seventh weld radio 1ph m question was identified by the NRC in inspection 9121. NilY has previously cor- led that the radiographic package for this weld did no' comply with all film qualin . qmrements prescribed by the Code. This non compliance, which concerns film densilb w as caused by the same interpretation error that caused the 44 density concerns identified during the conduct of tne WRRIP, and as summarized above. A detailed discussion of this issue is also provided in Section B.I.
The completion of these evaluations bounded and resolved the above listed weld radiograpu concerns. Therefore, NHY concludes that no further weld radiograph reinterpretation efforts are necessary. The bases for these conclusions ere the results from the WRRIP, evaluation of other radiographic techniques, and the numerous technical and independent reviews that have been conducted for weld radiography at Seabrook Station.
Section B.3 details t he bases for these conclusions.
Detailed Resoon=c to Ouestion Number 1 Root Cause Analysis Concluding that Concerns are Limited to the Double Wall Exposure, Double Wall Viewing, Source Side Penetrameter Technique As described in the letters dated July 8,1991 (NYN-91106), and September 17, 1991 (NYN-91151), the WRRIP was conducted to specitically climinate any question of doubt regarding the quality of the subject population of welds and their radiographic packages.
1 Refer to response to question nt.mber 2.
2
=
_ - - ~ ~ ~ _ _
h bject population (less As a result, the weld radiographic packages for 100t percent d by the NRC), were 1
of t e su weld radiograph packages previously reviewed and accep ef film quality and weld quality those identified were re examined to ensure strict compliance with every facet oAll of the weld ra criteria prescribed by the Code.
rigorously examined, and it was found that in 47 cases 17,1991 theyThis (NYN- does not mean of these requirements. As described in the letter dated September not achieve Code compliance. welds. These new radiographs were 91151), NilY has reradiographed all 47 subject in full 111 reviewers, and were found to be certified Level interpreted by independent,There new radiographs substantiate d that the original and confirm that the physica Pullman-compliance with the Code. d wclds themselves were in full compliance with the Co e, an Higgins and YAEC determinations regarding physical weld quality d were correct.
1 Pullman-liiggins and Y AEC reviews of radiographic film were conducte Then,e original reviews were intended to ensure The c-in accordancs
'he Code requirements. radiograph satisfied the film quality a was acceptable and that the both that the As to the latter, the degree of pu: cision employed varied with requirements of de Code. Where the density through the wr.J wrea of interest the apparent acceptability of the film.
were acceptable, ard the film appeared to meet comparative density firm density. On the other and penetrameter film may have requirements, only a few densitometer readings densitometer readings were taken.
were taken to c l se scrutiny, have been rejected after extensive f perfect radiograph with acceptabic, but marginal sensitivity, iew. The a ter c orejected may, so as to been accepted by Pullman Higgins and YAEC, butWRRIP questions and concerns regardmg s and their was speci eliminate the potential for ,
implementation of the WRRIP in tha manner was radiographs at Scabrook
<icient method of resolving any outstanding weld quality m.
considered to be the concerns. he 44 wc!d Notwithstanding the above, NHY has reviewed, i rnsforasgenerica resultimplications, of the t radiograph packages that were rejected due to film dens ty density conce concerns as a WRRIP, and the one (1) wrld radiograph This pack age also rejected forThis inves shortcoming is specific to result of NRC Inspection 9121.
in the original Pullman-Higgins and YAEC review process. inch nominal pipe size welds that the interpretation of radiographs performed on three (3) ide penetrameter radiographic utilized the double wall exposure, double wall viewing, source s technique, that is discussed below.
in question were aD performed using the double wall The 45 weld radiographs side penetrameter radiographic technique. This wall viewing, source exposure, double hree and one-half (3 1/2) inch outside technique is accepted by the Code for welds on t it is extremely difficult to diameter and smaller piping. With this particular techniqueAs described in the llellier Report #919-accomplish all the Code film quality req iirements. 91 (NYN.
12F, Revision t, which was attached to the NHY letter dated September 17,19The 91 UI), 'his technique is particularly difficult. i ll h ges as a function of the that the radiation passes through to reach the film, rad ca y c anThe larger the effective distance away from the pipe center, as depicted on the film.t d. This will cause composite through-wall thickness, the more the radiation will be attenua eThese dif a gradual transiticn of film density.
3 u
- -- ~
n inch nominal pipe size since the composite thickness that the radiation must travel through
- varies more so,than with smaller diameter- pipe utilizing the same technique,._ Hence, it is the doubie_ wall exposure, double wall viewing, source side penetrameter technique,-utilized
-on three (3) inch nominal pipe size welds, that presents the greatest demands on the reviewer's interpretive skills. ,
-This radiographic technliue l also requires even more extensive interpretation when it is used'on three (3) inch nominal pipe sire, heavy wall schedule 160 pipe. Specifically, with t'ais_ size pipe'it is necessary for the reviewer to interpret the weld area on the radiographic film without the benefit- of reference boundary markers being present on the film to depict the edges of- the weld .aren:of interest. The radiographs do have a 0* or 90* marker to -
indicate the center 'of the weld area of interest. For the 45. subject welds, the original '
Pullman liiggins and _YAEC reviews did examine the entire weld area of interest. However, the luck- of boundary _ markers- and gradual trt.nsition of film density at the outer fringes of
. the weld imposed by this technique created special challenges for the reviewers. It was within these small fringe treas where the WRRIP identified film densities that were not in strict . compliance 'with the Code requirements. The specific portions of the weld area of irterest that are in question with the 45 weld radiographs are depicted in Figure 1. Figure I shows the.use of the dot,ble wall exposure, double wall viewing, source side penetrametes radiographic technique on three.(3) inch nominal pipe size, heavy wall, schedule Ip0 pipe.
This figure shows the projection of the irgeident radiation as it passes through the O station and-onto the. radiographic film. (The 90 station projection is not shown for clarity). This figure illustrates the composite through wall thickness'that the radiation passes through the pipe wall to the film. Note the extreme variation of the composite thickness as the distance from the pipe center increases as projected onto the film, For example, radiation passing
~
along path "B" passes through 1.15 inches of pipe wall material. Similarly, radiation passing along path "A" passes through 2.26 inches of pipe wall material. _ As shown on the figure, the distance'between the points on the radiographic. film which intersect the projections of the latter two radiations paths, is only 0.393 inches. Thus, it is within this s' mall outer fringe j
of the weld = area of interest were the film density varies due to the large difference in l
. material thickness (l'15" to 2.26"). It is these specific areas on the radiographic film that caused the error in .the' original interpretation process.
NHY concluded that the root cause for these 4S welds is attributable to the
~ differences .in density at the edges of the weld area of interest under examination caused by lt _ this particular technique. 2A contributing cause is, in retrospect, the extent to_ which density L readings were taken.
NHY-evaluated the sensitivity concerns for the three (3) weld radiograph packages identified by the-WRRIP' and concluded that the original Pullman Higgins and YAEC reviews were correct in their determinations that these radiographs were acceptable per the Code.
As previously discussed, the WRRIP was specifically designed to be ultra-conservative in its deter ninations so as to eliminate all potcutial for future questions and concerns regarding _
- welds and their radiographs at Seabrook Station. These three (3) sensitivity concerns were -
rejected by the WRRIP since, after close scrutiny, it'was determined by multiple reviewers that;these. weld radiograph packages exhibited only marginally acceptable 4T sensitivity. By the guidelines of the-WRRIP, if an issue was the least bit controversial, it was conservatively l ' Refer to response to question number 2.
1 4
- - - - . . . . - ~ . -- , . . .- . - . - - - - ~ - . .
,y ,e
" identified for reradiography, Notwithstanding this, NHY concludes that the original Pullman.
Higgins and -YAEC determinations regarding the Code acceptability of these three weld radiograph packages _were correct. Additionally, the rcradiography performed as part of the WRRIP substantiates 'ind confirms the original determinations as to the Code acceptability of the physical welds.
As provided in the NHY response to the Notice of Violation, dated July 8,1991 (NYN 91106), NHY disputed the violation regarding six (6) weld radiograph package concerns that were identified at that time. Notwithstanding the fact that these welds were rcradiographed, NHY still concludes that these six (6) weld tr.iiograph packages are in compliance with the Code requirements, and therefore, that the original Pullman Higgins and YAEC determinations regarding Code acceptability were correct.
Based on the root cause analyses discussed above, NilY has concluded that the concerns are limited to the double wall exposure, double wall vieviing, source side -
penetrameter technique.
l B.2 Pesults of NHY Review of Radiographs taken with the Double Wall Exposure, Double l
-Wall Viewing, Source Side Penetrameter Technique NHY is confident that the 44 weld radiograph packages that were previously identified during _ implementation of the WRRIP comprise the complete set of radiographs affected by the above- described interpretation error. As described in the letter dated September 17, 1991 (NYN 91151), the scope of the WRRIP provided a 100 percent reinterpretation of all Pullman-liiggins field- welds:
'that required radiography in order to meet the ASME Code, that is three (3) inch nominal pipe size and smaller, where the initial Pullman Higgins Level 11 (or !!!, where the only Pullman .liggins review was performed by a Level Ill)
- review signature occurred prior to October 1,_1982, and where the double wall exposure, double wall viewing radiographic technique was used with source side penetrameters, excluding _any welds previously accepted by the NRC."
This 100 percent review of the 'potentially affected population idun ified the set of-44
-actually affected weld radiograph packages.
The WRRIP : review also performed additional bounding conditions analyses that confirmed the validity of the parameters utilized- to determine the scope of the WRRIP.
The first of these additional population samples included field weld radiographic packages meeting all of _the program population parameters with the exception of the October 1,1982 date of initial Pullman Higgins review. NHY and Hellier - Associates, Inc, reviewed a total of twenty (20) of the radiographic packages in the period immediately following October 1,
-1982, and _ documented that each of them complied with the. Code requirements. This sample c'onfirmed the effectiveness of program enhancements and corrective actions taken after October 1,1982, to improve the construction era radiographic examination process.
The second bounding conditions analysis, carried out in order to confirm that the proper selection of key program parameters had occurred, involved a research of the field weld radiographic packages thit were three (3) inch nominal pipe size and smaller but 5
.f= .O Involved a different radiographic filming technique. This analysis included radiographs taken during the entire c'onstruction era. This analysis confirmed the selection of the double wall exposure, double wall viewing-with source side penetrameter radiographic technique as a
-valid bounding- parameter in ;that- out of a collective total of 55 previous and current independent' weld examinations, of radiography performed by a different technique (double wall exposure, single wall. viewing), all were found to be acceptable. .l J NilY further concluded that_ there were no implications for smaller pipe diameters j
- radiographed with this technique. To support this conclusion, Nif Y has investigated the use of the double wall exposure, double wall viewing, source side penetrameter technique on welds _ smaller than three (3) inch nominal pipe sire. The results of the WRRIP indicate that it 'is only with the three (3) inch nominal pipe size where these interpretive concerns occurred.
NIlY believes that these reviews have reexamined the entire set of Pullman-liiggins field weld radiograph packages which may have been subject to the aforementioned l radiographic-interpretation error. ,
B.3 No Other Generic implications as a Result of the Foregoing Weld Concerns NHY_ has' investigated the concern regarding gcnerie _ implications raised in the first question and has concluded that the generic implications do not extend beyond the population of weld packages evaluated in, and responded to by implementation of the WRRIP-. _ The following provides the bases for this conclusion.
As presented above, NilY has previously evaluated the weld radiograph sensitivity
. concerns identified for the six Notice of Viciation welds, and the three WRRIP welds, and has concluded that the Pullman-liiggins and 'r A EC reviews were correct in their determinations that these radiographs were acceptable per the Code. There are no generic implications associated with these weld radiograph packages since they are in compliance with the Code.
NHY has also reviewed. the potential for similar interpretation errors with other radiographic techniques. This review indicated that for all other techniques (e.g., panoramic and double wall exposuie, single. wall viewing), the radiographic films inherently contain less variations-in film density. Unlike the double wall exposure, double _ wall viewing source side penetrameter technique, these other techniques utilize station or tioundary markers which clearly delineate the full extent of the radiograph which must be reviewed for density.
Additionally, ~with other techniques there is conservative overlap onto the adjacent station's film. Based on this and the foregoing, NilY concludes that the potential for this interpretation error -is limited _ to situations where the double wall- exposure, double wall viewing, scurce side penetrameter technique is utilized on three (3) inch nominal pipe size welds.
' In addition to the above, throughout the life of Seabrook Station, numerous technical, documentation and -independent reviews have been conducted for the weld radiography at Seabrook Station, and these reviews collectively comprise a significant sample of the weld radiograph population. During the conduct of these reviews, any weld radiograph quality concerns have been evalunted, and corrective actions implemented av apprapriate. Due to 6
_ _ , . _ _. - - _ -.m . _ . _ . . . .-
l
- the. comprehensive-nature and varied scope of these reviews, NilY- has concluded that weld t radiograph ' quality concerns have been rer,olved; l
in summary, based on the foregoing NHY conclades that there are no generic
.imolications, other than those evaluated in, and responded to by implementation of the WR RIP, NilY- further- concludes that no further weld radiograph reir.terpretation efforts arc _ necessary.
C. Ouestion Number 2
?The contractor report lists seven weld radiographs rejected ior unacceptable film.
quality but the report summary only lists three rejects for sensitivity. What criteria, in addition to inadequate density, caused rejection of the other four radiographs?"
Resoonse to Ouestion Numb,,gt2 As-described in the Hellier Report #91912F, Revision 1, which was attached to the NHY letter dated September 17,1991 (NYN-911J1), a total of seven (7) weld radiographs were rejected for. unacceptable film quality. Three of these weld radiograph packages were rejected solely due to inadequate sensitivity. The remaining four film quality rejections weie due primarily to density concerns, in addition to sensitivity concerns.
The. NHY reinterpretation results associated with these same seven (7) weld
. radiograph sets' were in essential agreement with the Hellier results.. As described in- the September 6, and September 17, 1991 NHY transmittals (NYN 91142 and NYN 91151,.
-respectively), the NHY and Hellier reinterpretation processes were conducted by independent teams of highly qualified radiographic film interpreters utilizing ultra-conservative acceptance l
l criteria in order to ensure Code' compliance beyond all question or doubt. If either team found-cause for concern in a particular radiograph set, such as a professional judgement call on marginal _or inadequate sensitivity, and if there Lwas less than full concurrence between the : teams, then the weld was simply reradiographed in order to be most conservative in resolving any concerns. Notwithstanding this process, however, a m' ore specific NHY analysis ]
l of the seven (7) Hellier radiograph sets identified as exhibiting unacceptable film quality has !
-. been - conducted._ NHY- has concluded that while being in essential agreement :with Mr.
Hellier _ that the film sensitivity is marginal, the original Pullman Higgins and YAEC determinations regarding sensitivity were correct in terms of Code compliance. The essential
- . 4T iirage -qu 'ity indicator hole was discernable on the original films in question, and the
! issue has' bet further rendered moot through reradiography.
D. Question Number 3
" Table .2 of' Attachment A to the NHY report lists 55 welds. To what does the number 59 (identified as the population confirming the acceptability of the single wall viewing technique) used in your "second bounding condition analysis" refer and how
- were the 59 (or 55) selected for review?"
7
4 l
Resoonse to Ouestion Number 3 l' ages four (4) and ten (10) of the WRRIP Report transmitted in the NilY letter dated Sep;embe- 17,1991 (NYN 91151), state that the total number of previous and current independent examinations of rediography performed using the double wall exposure, single wall viewing techniques was 59 This is a typographical error. The correct number is 55.
Table 2 of Attachment A to that report correctly indicates that the actual number of welds that are in this category is 55.
The 55 welds listed in Table 2 of Attachment A to the WRRIP report were selected as follows. Weld related NRC inspection Reports and NUREG-1425 were reviewed to determine that population of welds reviewed by the NRC that met all of the common factors parameters, except for the radiographic technique. For this Table, the radiographic technique of double wall exposure, single wall viewing, replaced the original technique parameter of double wall exposure, double wall viewing, with a source side penetrameter.
Inspection of Table 2 of Attachment A to the WRRIP Report indicates that the welds reviewed by the NRC comprise 51 of the 55 welds listed. The remaining four (4) welds were reviewed as part of the WRRIP before the final list of welds, which satisfied the WRRIP common factors parameters, was finali/cd. As a result, NilY added these four welds to Table 2 of Attachment A to the w F RIP Report. These four welds are the only welds that utiFzed the double wall exposure single wall viewing, technique, that were re-reviewed as part of the WRRIP.
8 I
1
o FIGURE 1 -
Radioactive Double wall exposure. double Source- wall- - viewing, . -source side
-penettameter radiographic technique on' a 3 inch- nominal
- pipe size, shedule 160 pipe weld,
.I f.
i l
\
i
.t A B s
0 a.
r- ) "[ B M,
n 4
- I -
- 90* 0 v:
-_L 7.
+ E i nj 9i Radiographic film -
- =M L
2.4 72 _
r- -_.___--------_-_-_-_________.-._-___.__---.__--.__..___.__.._A--._-..._.A._
4 y ,'
New llampshire Yankee September 27, 1991 ENCLOSURE 2 TO NYN-01157 SUPPLEMENTAL, Hell lER ASSOCI ATES. INC. R EPORTS l
1 I
f I'
~
i i
l.
I l
l
Sucolemental Hellier Associates. Inc. Reoorts llellier Associates, Inc. Report # 91912F, Revision 1, was included as Attachment B to NHY letter dated September 17,1991 (NYN-91151) [ Reference (c)]. Enclosure 1 to Hellier Report # 919-12F, Revision 1, has been revised. Attached as part of Enclosure 2 to this letter is Hellict Report # 919-12F Revision 2.
Page 7 of IIellier Report # 919-12F, Revision 1, listed five field welds reviewed by M. McLean of Hellier Associates.
Revision 2 to Hellier Report # 919-12F reflects the fact that Mr. C. J. llellier also reviewed the field welds. The additional welds reviewed by Mr. llellier are the following:
1-S L-X-6301 -F0102 1-SL-X-6401-F0102 1-S L-X-6501- F0102 1-SL-X-6601 F0102 1 CS-360 06 F0601 Also included in this enclosure is Hellier Associates, Inc. Report # 919 20F, This second Hellier Report (919 20F) provides the results from reviewing the following two additional weld populatiot.s:
- 1. The first population included twenty field welds selected to verify the parameters used to establish the Weld Radiograph Reinterpretation Program. This population of welds included field weld radiographic packages meeting all of the program population parameters with the exception of the October 1,1982 date of initial Pullman-liiggins review. Hellier Associates, Inc. reviewed these field weld radiographic packages and found them acceptable. Section B (page four) and Table 1 from Attachment A of the Completion Report [ Reference (c)] provides the discussion and listing for this sample population of field welds.
- 2. The second Hellier Report (919-20D) also addresses the results of reviewing the reradiography of the 47 welds identified by the Weld Radiograph Reinterpretation Program. Hellier Associates, Inc. independently reviewed the new radiographs and concluded that the welds and their radiographs fully comply with the requirements of the Code. Section C.3 of the Completion Report [ Reference (c)] provides additional details regarding WRRIP Corrective Actiin results.
- . . ; SEP-20 '91; FR1 15:31: ID:HELLIER ASSOC .TEL N0:203-739-6732 ::660 pc; s
i HELLIER I i
n REPORT # 919 12F Rev 2 PREPARED FOR NEW HAMPSHIRE YANKEE SEABROOK, NEW HAMPSHIRE l
.i
{
o lr PREPARED BY L.
p Charles J l er {
DATE -
. ' #d dak 0 // f /
f- ,
4 3
, [EEP-20'9tFRI15:25 ELLIEP 550C TEL to: 202-72?-6722 u660 P02 -
e L ,
i EXECUTIVE
SUMMARY
HELLIER was contracted by New llampshire Yankee to provide an independent and unbiased review of one htmdmd (100) weld radiographs taken by Pullman liiggins prior to October 1,1982 of three inch nominal pi x size and smaller. The radiographs were taken with the double wall exposure, double wall v, ewing technique which is in compliance with the ASME Code. Secdon V.
The inherent difficulties with this technique requires precise set up and exposure in order to achieve required radiographic density coverage.
Of the 100, forty four (44) were found not to be in compliance with the ASME Code requirements due to inadequate coverage based on code density requirements and three (3) due to unacceptable quality levels (essendal penetrameter hole not visible).
CONCLUSION Based on the results of this review, it can be concluded that the technique used for some of the radiographs for under 31/2" diameter pipe welds prior to October 1,1982 was not aroperly applied to achieve all film density criteria necessary to strictly comply with each of tx applicab!c Code requirements. The film quality was sufficient to allow HELLIER to conclude that there were no apparent physical weld concerns in the welds reviewed.
RECOMMENDATION
- It is recommended that the welds which are not in compliance w' h the ASME Code requirenents regarding density or film quality level be n:-radiographed until compliance is achieved.
2 1
.. , SEF 91 P! 15:25 !D HELLIER ASSOC TEL NO:202-729-6722 t:MO F04 Intmduction IELLER has been engaged by New llampshire Yankee for the ptupose of providing; an independent Code compliance review of a number of field weld radio piiphs evaluate ( and approved by Pullman Higgins personnel prior to October 1,1982. T2csc welds are 3" nominal pipe size and smaller and were onginally radiographed using the double wall exposum, double wallviewing technique.
Pennnel IE11IER penonnel involved with this review included Charles L Hellier, President, Kenneth Coryell, Vice President, and Michael Mclean, Senior Level m. All personnel carry IELLER l Level m Certifications and hold American Society for Nondestructive Testing 1.cvel m Cenificates in Radiography Documentation to support the certifications has been given to New Hampshim Yankee.
Review All radiographs wem myiewed to AShE Section V and Section M,1977 Edition and Pullman.
i Higgins Procedure IX-RT 1-W77; and New Hampshire Yankee Procedure 11230, Rev O dated l
8/28S1 (Level m Review of Radiographic Film). While each radiograph was Itviewed for total Code compliance, emphasis was placed on weld coverage and film quality level. Weld coverage is primarily a function of density achieved thmugh the ama ofintettst.
He bars density is established by taking a density reading thmugh the penem c.eter. Density readings in the area of interest (AOI) cannot vary bg greater than +30%, -15% from the base I
density established through the penetrameter. The Lode funher stipulates that the minimum density for each film (single film viewing) cannot be less than 2.0 or 1.3 (composite film viewin g).
De maximum density cons dered acceptable for evaluadon by the Code is 4.0 (single or composate viewing).
When pipe welds with relatively small diameters are radiographed using the double wall exposum and double wall view technique, (either elliptical or superimposed image) the effective composite thmugh wall path the radiation passes through, radically changes as the distance away from the pipe center inemases. (See FJgurt # 1).
- j. 4 .., ,
3 l
, . SEP-20 '91 FRI 15:36 !D HELLIER A?50C TEL PCi!O3-739-6732 :3660 F05 If a typical radiographic technique produces an itnage with good contrast (beneficial in radiography in order to observe density changes resulting from small cross secdonal thickness changes), the density variations as a result of this effective composite through wall path will be signihcant.
If a low contrast radiogra)h is taken, the resu!r will be a more uniform density throughout the area of interest thereby minim ring the possibility of falling outside the code required density range.
To summanze, the lower contrast technique resulting in Ereater coverage does not provide the best quality image forint:rpretation.
This rationalis not intended to provide an excuse for not complying with the Code but merely to point out the trason for the density variation pr.;blems. Increasing the number of exposures to achieve greater coverage would have been one solution, ErmlL1 The results of this review are contained in Enclosure # 1. The categories are (1) Acceptable,(2)
Inadequate coverage due o density variations either outside the -15% minimum or less than the 2.0 required, and (3) Unacceptable due to film quallry level not being achieved. The Irview did not disclose any apparent concerns regarding weld quality. Subsequent icports will address the in-process tv-radiographic results.
Rernmmendationt Re-radiograph those welds considered unacceptable to achieve compliance with Code requirements regarding radiographic technique and coverage.
4
,- , SEP-20*'9A FR! 15:37 IDiMELLIER ASSOC TEL N0:203-739-6732 uG60 PO6
~
, ENCLOSU.RE # 1
. g innamnate pensury Unmnahte Mim challev 1-CS 302 04 F0402 1 CS 302-01 F0103 1.CS 302-03 F0301 1 CS 301-06.F0602 1 CS 303-05 F0504 1-CS 303-05 F0503 1 CS 303-05-F0502 1 CS 303 03 F0303 1-CS-302-04 F0403
' 1-CS 301-06-F0601 1-CS 327-02 F0201 1-CS 327 02 F0210 CS 328 01-F0103 1-CS-303-05 M)505 1 CS 318-01.F0101 1 CS 318-04 F0404 1-CS 327-01 F0103 1 CS 327 01.F0105 1 CS-318-04-F0402 1 CS-327 01 F0102 1-CS 328 03 F0301 1-CS-332-02 F0202 1 CS-340 01.F0104 1-CS 328-02-19205 1 CS-303-04 F0405 1 CS-327 02 F0203 1-CS-327 02 F0203 1-CS-324 02-F0203 1-CS 327-02 F0211 1 CS-328 01 F0101 1 CS-340-01 F0105 1-CS-355-01 F0108 1 CS-355-01 F0111 1-CS-355-02 P0203 1-CS-355-02 F0204 1 CS-355-03 F0303 1 CS 303-03 F0302 1 CS 355 01-F0101 1<CS-355-01-F0103 '
1-CS-355 01 F0106 1-CS 355-01.F0105 1 CS-355-01 F0107 1-CS-355-04-F0404 1 CS-355-04-F0403 1-CS 355-04-F0402 1-CS-355 04-F0401-1 CS-355 05 F0502 1 CS-355-05 F0503
, 1.CS-356 01 F0104 i ~ 1-CS-355-09 F@06 1 CS-355-09-F0903 L
5 L
, SEP-70 '91 FR! 10t!? !D h?.LLIEG M10: TEL tCt102-?!9-6722 0640 Po'
, Acss:n inskuuite Density Unnecentable Film Ocnihv s 1 CS 355 08 F0802 1 CS 355 06 F0603 1 CS 355-08 F080) 1 CS 355 09 F0902 1.CS 355-06-F0602 1 U 11 F0105 1 CS 357 05 F0504 ^
l CS 360-01 F0101 1 v8 360 02 F0201 1 CS 3@03 F0302 1 CS-360-04 F0402
, 1 CS 360-04 F0403 m 1 CS 360 05 F0504 1.CS 360 09 F0901 1 CS 364-03 F0303 1 CS 364 03 F0306 1 CS 364-03 F0304
=
1 RC 97 01 F0106 1 CS 365 02 F0201 1 CS 366-02 F0205 l RC-97 03 F0304 1 RC 97 03 F0309 1 RC-97 02 F0204 1 CS 363 01 F0103 1-CS 36011 F1102 1 CS 364 03-F0302
' 1 SB 1304 02 F0201 1 SB 1304 02 F0201 1 CS 36011 F1101 -
1 CS 360-12 F1202 1 CS 36012 F1201
_ l CS 364 03 F0307 1 CS 360-09 F0902 1.CS 318 01 F0103 1 CS 318 04-F0403 1-CS 303-04-F0401 1 CS 303-05 F0501
, 1 CS 324 02 F0201 1-CS 324-02 F0201 1 CS 327-01 F0104 i 1 CS 327-02 F0202 1 CS-327 02 F0204 1.CS 327 02-F0205
_ l-CS-328-01 F0102 1-CS 328 03 F0102 1 CS 328-02 F0203 1 CS 328 02 FU201 1 SL-X 6301 F0102 1 SL X-6401 F0102 1 St-X 6501 F0102 1 SL X-6601 F0102 1-CS 360-06 F0601 l
m "M
, EEn-20 ' 91 FR l 15: 30 !D HELLIER AESCC TEL tO:203-729- 67: us40 PM
- ' f,00 AC E
.s e
I l EXAMPLE Outside Diameter 3.0" Wall ?hicknese 0.4" SPD 20,o" i
Total bffective t.hicknces l through which the radiation passes:
O c/1. 0.000" O b" of C/L 0.875" 0 1" of C/L 1.187" l
1 l l
a.
I 1
1 t'
I
\
II
\
+ PIPE WELD FIGURE #1 RADICGPAPHIC PII}f
-. k s f l
c/L b" 1"
l 4
I I
HELLIER ,
REPORT # 919 - 20F PREPARED FOR NEW HAMPSHIRE YANKEE SEABROOK, NEW HAMPSHIRE i
PREPARED BY, N Nu chuw J.ga otrE AAA '
z'r; ar< /
'.g s
d I
1
'_O __.
^
-m.mc- e-.wn ---- -r---.,--e+:-.e- w~weun--<w.c- w-__ _- - - - ---a - ---
-m- - Jn g' .
t innninetinn This report contains the results of two additional radiopphic review efforts conducted by HELLIER for New Hampshire Yankee at the Seabroo c huclear Power Station.
Poc October 19R2 Sample Radio hs fcr a s. ample of 20 welds were reviewed by HELLIER level 111 >ersonnel and found to Acceptable. Of the twenty, six (6) weto reviewed by Charles J. Itellier and signed accordingly. He level Ill personnel signed the radiograph inspection reports to indicrte review and acceptance. Mr. Hellier initialled the fourteen radiograph ins ption reports to signify his concurrence that the radiographs were acceptable. See Tab: e I for a listing of the twenty (20) welds.
Pre-Octaher 1982 Re Inmeetion ne forty seven (47) sets of weld radiographs originally examined prior to October 1982 were re-radiographed in order to achieve code compliance. The welds were o.iginally considered not to be(44)
Code density requinmentt in compliance or unacceptableby HELLIER quality level due to inadeg(3).uate coverage Im1 LIER Level III personnel reviewed the re-radiography for the forty seven (47) welds FF11 IFA orip*nally determined not to be in compliance. The HELLIER review of the fracy-seven (47) re-radiographed field welds found them to be acceptable and in full compliance widi the Code. De Level m personnel documented their reviews on NHY's Contractor Radiograph Review Pn>cedure forms. Table 11 lists the forty seven (47) field welds.
l
- -- -s-- - -,-,-e y, -,,, y --
- l. .
l l
POST OCTOBER 1982 SAMPLE 1 CS 318-04-F0405 1 CS 35103 F0301 1-CS 351-03 F0302 1 CS 36010-F1001 1 CS 36010-F1003 1-CS 365-01 F0104 1 CS 365-01 F0108 1 CS-365-04-INO2 1-CS 365 M F0407 1 CS 365-04-F0408 1 CS-365-04 F0409 1-CS 366-02 F0205 1.RC 15 01 F0103 1 RC 15-01 F0104 1 RC.1541 F0105 1 RC 1541.F0106 1 RC-44-01-F0104 1 RC 5942 F0201 1 RC 59-02 F0202 1 RC 5942-F0203
.. + . , . +
l -
PRE OCTOBER 1982 RE INSPECr10N 1 CS 303 03.F0302 1.CS 303-04 F0405 1 CS 318 01.F0103 1 CS 318-04-F0402 1 CS 318-04-F0403 1 CS 324-02 F0201 1-CS 324-02 F0203 1.CS 327 01 F0102 1.CS 327 01.F0103 ,
1 CS 327 01 F0104 1 CS.327-02-F0202 1.CS 327-02-F0203 1 CS 327-02 F0204 1 CS 327-02 F0205 1 CS.327-02@210 1 CS 327 02.F0211 1 CS 328-01.F0101 1 CS 318 01 F0102 1 CS.328-02-F0201 1 CS 328 02 F0203 1-CS 355 01-F0101 1-CS 355-01 F0105 1 CS 355-01 F0106 1-CS 355 01.F0107 1 CS-355-01 F0108 1 CS 355-01-F0111 1 CS 355-02 F0204 1 CS 355 03 F0303 1 CS 355-04 F0401 1 CS-355 04-FO402 1.CS 355-04-F0404 1-CS 355-%F0602 -
1 CS-355-06 F0603 1-CS-355-08 P0809 1-CS 355 09-P0902 1-CS.355-09-P0903 1 CS 356-01-F0105 1 CS 3@01 F0101 1-CS-360 02 F0201 1-CS 360 04-PO403 1-CS 3@05 P0504 1 CS 3@06 F0601 1-CS.360-11-F1102 1 CS 364-03 F0302 1 CS 364 03 F0306 1-CS-364-03 F0307 1-SB 1304-02 F0201
"~2:_ __
~
, e' . . ,o - e
.e .p
' ,y GOUP.CE
- 6 ;
EXMtPt.E Outside Diameter 3.0a Wall Thicknese 0.4" 5FD 20,oa .
l 1 l Total effective thicknese
-through which the radiation passes:
9 C/L 0.800" 4 4" of C,'L 0.875" 9 1" of C/L 1.187" l
l l
1 i
l 3
1 + PIPE WELD
-FIGURE'#1 N exDioasu nic rita
. I l.A /
,ii -
C/L h" '1"
,. --- ~ ,,,, n-,-vn - - - ,.. .,,..n,,- ~~,,.n- ., -- ,--,,.n,,,n,,--..,,_+,-,,.,,+,,,,,~.,n,.w.a. --
w,,-,, ,,,,~,.,,,,,-r ~w-,
,.s New Hampshire Ya ikce September 27, 1991 ENCL _OSURE 3 TQ NYN 91157 ERR ATA FOR NHY LETTERS I
-.a -ww.--.,. --y
q ., s O
' Errata For NilY 1.etters Enclosure 3 transmits errata for the N11Y letters dated September 17, 1991 (NYN 91151) [ Reference (c)], which transmitted the results of implementing the Weld Radiograph Reinterpretation Program (WRRiP) and September 6, 1991 (NYN 01:42) l Reference (b)], which transmitted the WRRIP description. NilY incoerectly identified the NRC Inspection, which occurred during the weeks of August 19 and 26,1991, as NRC Inspection 9127. The correct identificatloa is NRC Inspection 9121. The remaining errors apply to Tables 1, 2 and 4 of the Completion Report litclerence (c)]. Tables 1 and 3 j incorrectly list the nominal pipe- sizc for three welds. Table 4 incorrectly lists the references for two field we!ds. The following tables provide the original and corrected references.
Table 1 Weld Oricina pine Sire Drrect Pipe $71,, l 1 RC-91410005 F002 3 1*
l RC 91410005 F005 3" 1*
Table 3 l l
Weld Oricinal pine Sire Correct Pine Sire 1 Ch 318 04 F0204 3" 2" l Table 4 Oricinal Reference CorrySL,jt_fference 1 CllS 1208 01 F0104 NRC IR 80 60 NRC 1R 80 06 1-CBS 1208-02 F0202 NRC IR 80 60 NRC 1R 80-06
. . _ , _ _ _