ML19339C039
| ML19339C039 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 05/23/1980 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | Gallagher E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML19339C036 | List: |
| References | |
| ULNRC-354, NUDOCS 8011170212 | |
| Download: ML19339C039 (14) | |
Text
.
_ ).Yi Ny. e, ~~ Q UNION CLECTRIC COMPANY 69 00 C R AT 807 STRCCT
- ST. Louts G
May 23, 1980
-. u ~ o o o. css:
..o..o....
ST. Lova s. MO. 6 3s 6 6 Mr. E.
Gallagher U. S. Nuclear Regulatory Commission Region III 799 Roosevelt Road ULNRC-354 Glen Ellyn, Illinois 60137
Dear Mr. Gallagher:
RESPONSES TO'NRC QUESTIONS ON UE EMBED REPORT--CALLAWAY PLANT My letter to you dated April 24, 1980 (ULNRC-349) listed 17 questions generated during our meeting of April 10, 1980 concerning the subject report.
The following summarizes our responses to these questions:
1.
AWS Dl.1-75 is applicable for the manual welding of threaded rods and as such, is invoked for welding in Specification 10466-C131, with technically acceptable exceptions as noted for undersize, profile, uneven legs and undercut.
2.
The welding of threaded rods or anchors is in accordance with Dl.1-75 with the following exceptions:
A.
The leg of the weld adjacent to the anchor may be up to 1/16 inch smaller than specified on the design drawings.
B,.
Unequal leg welds are permitted.
C.
Weld ptrfile and convexity requirements for these welds need not be imposed (but concavity limits apply).
D.
An undercut of up to 1/16 inch for 10% of the weld langth may be permitted.
These deviations are supported as follows:
A.
The undersize leg is satisfied by oversizing the welds on-the design drawings such that even with the undersize deviation the welds will satisfy design requirements.
B/C.
The variation in weld profile including unequal legs and convexity does not result in an'offective throat thickness less than required to satisfy the design strength.
e..,nm I' }("
l 8011170$ll' ktl 4
e.g SOLVING PRODLEMS THROUGH INVENTICN & INNOVATION w
Mr.
E. Gallaghbr' Mty 23,.1980-Page.Two D.
Undercut is limited such that-the reduction in cross-sectional area is less than that which occurs as a result of the threads.
l The installation (fabrication) of welded studs is in accordance with AWS D1.1-75, Section 4.0 Part F as it applies to "other than shear connectors." In Rev. 9 of Specification 10466-C-131 the inspection requirements-
- of.Section 4.30.1 (applicable to shear connectors) were j
imposed in lieu of the requirements of Section 4.30.2 (applicable to other than shear connectors).
See also' response to; question 6.
3..
The. smallest weld size shown on the-drawings has been and is 3/8 inch.- Therefore'even with 1/16-inch undersize the minimum weld size is'in accordance with AWS Dl.l.
4.
Permissible weld undercut values for buildings have been revised ~in'the 1980 edition of AWS Dl.1 (see Attachment "A").
The permissible _ weld undercut values of 1/16 inch, l
however, are not. applicable to the embeds in muestion.
5.
We are certain-that Cives inspected many of the plates listed in NCR 2-0831-C-B of which some were. machine-welded and others were manually-welded.
It should be noted, however, that NCR 2-0831-C-B.was-generated over a period of several months; i
thus Cives may not have inspected all the plates contained in the NCR.
t 6.
AWS Dl.1-75 (Section 4, Part F) identifies.two types of studs, characterized by their intended use.
A.
Shear connectors - used in composite stcel-concrete construction (sEe Section 4.25) and
~
Concrete anchors - for other than composite steel-B.
concrete construction to attach' mea.bersand' connection devices'to concrete.
I AWS provides appropriate installation and inspection criteria for each of these stud types.
By AWS definition ~the machine-welded studs'in question are concrete anchors and it was on~
this basis that production initially proceeded.
During the-in-process = inspection (quality control), studs on which a 360 degree weld-fillet was not obtained were either replaced-or repaired in accordance with AWS Dl.1-75 Subsection <4.'29 i
for concrete anchors.-
During the fina1Linspection, at least one stud in every 100 was bend tested in accordance with Subsection 4.30.2.
t d
t 9~K" g
t?
-"e-
-T-1
'-ti14
"t i
T'f
Mr. E. Gallaghcr May 23, 1980' Page Three 1
Section 9.6 of Bechtel Specification 10466-C-131 Revision 9 upgraded inspection requirements by adding bend testing of studs having less than a full 360 degree weld fillet, in accordance with AWS Dl.1 Subsection 4.30.1.
This addition provided visual evidence that studs with less than 360 degree weld fillet were inspected and minimized the possibility of future questions or another massive reinspection effort to prove the acceptability of the welded studs.
No documentation of the bend tests was required either before or after Revision 9 of Specification 10466-C-131; however, Bechtel inspection reports indicate that bend testing was performed as required.
7.
The Cives letter to Bechtel (SL:134) emphasizes Cives' view-point that the product is classified as concrete anchors and not shear connectors.
The basis for this is explained in the answer to Question 6.
Please note that the statement in Question 7:."No other sections of AWS apply to our work" does not appear in the referenced Cives letter.
Rather, the letter states that: "No other sections which refer to shear connectors will apply to our work."
The referenced Bechtel letter to SNUPPS (BLSE 5227) was written purely to clarify commercial considerations.
The letter further reiterates the need for a full 360 degree weld fillet or bend test.
The revisions cited to AWS Dl.1-77, Section 4.0 resulted in relaxations to the AWS code which were not granted to the supplier.
8.
The probability analysis was performed using well-defined and accepted statistical rulea.
The data used was generated by field inspection of 81,673 studs and analytical computation of load carrying capacity of machine-welded plates embedded prior to June 9, 1977.
The analysis established that the probability of a plate failure affecting a safety-related system was significantly low.
There is evidenaaof multiple defects per embed; ten plates are in this category and they are shown in Attachment "B".
0 weld) and failed Embeds with defective studs (less than 360 studs are listed in Attachment"C".
9.
During the months of July and August, 1977 Cives Corporation reinspected over 400 manually-welded plates of which 80 plates (not a majority) were found in violation of the Specification 10466-C-131, Rev. 9 and design drawings C-00ll, Reev. 7 and C-0012, Rev. 8, and were therefore repaired by Daniel under Cives' supervision.
The welds inspected had an uncersize not exceeding 1/8 inch.
Bechtel Quality Surveillance prior to June 9, 1977 was performed in accordance with AWS Dl.1-75 and Specification 10466-C-131.
Circa 10 percent of the material for this order was inspected by Bechtel which constitutes
Mr'. E. Gnllcgh3r May 23,.1980 Pcgo Four more-than a representative sample.
The items in the sampling were visually inspected 100%.
There was no indication at the time of a generic welding problem.
In addition to welds, Bechtel Supplier Quality inspects for physical dimension, paint thickness, documentation, general workmanship, etc.
10.
The difference in number of machine-welded studs inspected is simply due to the fact that the inspections were conducted-at different times and the quantity of embeds available for inspection changed.
DIC used the term " reject" to indicate failure.
DIC rejected 106 studs out of 96,472 inspected, a failure rate of 0.11%.
Cives rejected 66 out of 81,673, a failure rate of 0.08%.
These results are comparable.
11.
The" load capacities shown in Appendi>: B Table 1 under the heading: " Load Capacity for 27 ksi" represent the allowable tension load on the plate assuming that the load was applied in the middle of the plate bounded by a four-stud cluster.
Note that the capacity is computed only for a four-stud cluster regardless of the number of studs on the plate; hence, the same capacity is listed for all lengths of plates.
The reduced load capacities in Zones 1, 2 and 3 were determined using a plate-bending stress of 36 ksi (the minimum yield strength of 36 ksi was used since this is a failure analysis) and assuming that one of the adjacent studs failed (zero load capacity).
The reduced load capacities were used to determine the probability of plate failure due to imposed loads.
12.
The reduced load capacities for manually-welded unthreaded (or headed) studs are not addressed in the report since the relaxed welding requirements of Specification 10466-Cl31 are not applicable to welded studs of this type.
The appropriate inspection requirements for the manual welding of unthreaded studs are found in AUS D.1.1.
The fabricator has confirmed that he is utilizing these requirements for manually welding headed studs.
The load capacities in Table 1 are based on tension applied in the middle of a four-stud cluster on each plate; the capacities for Table 3 are based on a combination of shear and bending n.o m e n t.
The weld size required is that-necessary to develop the capacity of the threaded rod.
When the specified weld size exceeded that required, the plate capacity was not affected.
13.
An average weld deficiency of 1/8 inch or less for all studs provides adequate strength (within allowable stresses) for design loads only if the individual welds have average deficiencies of 1/3 inch or less.
A plate having-localized weld deficiencies greater than 1/8 inch average per stud could be locally overstresred.
In Enclosure 8 to UE's March 10, 1978 report, we attempted to characterize the condition of manually-welded embeds
Mr. E. Gallaghsr May 23, 1980 Page Five using DIC inspection reports with less than complete information.
As indicated in the ground-rules for the survey made in this enclosure, if a DIC inspection report indicated a weld defi-ciency greater than 1/8" without identifying the extent of the undersize around the circumference of the stud, it was assumed that the deficiency extended 3600 around the periphery.
An average weld deficiency for all studs on the plate was then calculated, recogniziag that the resulting weld deficiency would be overstated.
This-survey did not consider localized undersize as a determining factor.
14.
The yield stress of 43 ksi was based on CMTRe for the threaded rod material used prior to June 1977.
The CV.TRs were an attachment to Cives letter SL:124.
Note that the results of this analysis were not used to arrive at the conclusions in the report.
15.
The referenced letter was written when the reinspection effort was in process and provides only partial results.
The numbers in the probability analysis incorporated this data along with the reinspection results of the balance of the plates.
~
16.
As a result of the referenced letters, an inspection of embeds was initiated at Callaway.
The results did not indicate evidence of weld problems.
This is documentcl in Attachment"D".
17.
Entry
- 44 was rejected since a reinspcction report by Cives found the plate to be acceptable.
The probability analysis, based on the reinr action of more than 81,000 machine-welded studs, was perfcn cd using well-defined and accepted statistical rules.
Thit is an appro-priate approach since an individual stud or plate failure does not necessarily compromise the overall tafety of the system or the plant.
The degree of redundanc.y in design, and the strict overall quality control employed in the design and construction of nuclear power plants limits i.no mode of ultimate f ailure of various components and systens anc reasonably assures that an undue risk is not imposed by f ailure of an individual component such as a stud.
The probability c.alysis underlines this rationale by incorporating various fact Ts which must be considered in assessing the impact of the in pection results on the safety of the plant.
In the case of manually-welded threaded rods an analysis was made assuming an undersize of 1/8 inch for a 'ull 360 degrees on every stud.
This assumption was supported by the Cives reinspection of approximately 400 plates and a reinspection effort by DIC, UE and Bechtel on 45 plates.
Assuming the 1/8" undersize extends completely - arcuirl the periphri of every anchor is a significant conservatism, s
D*f]D "D 'T T M a &Ju o f
. d kinLa
Mr.
E. Gallagher May 23, 1980 Page Six In addition,_the level of conservatism'in the design for this type of embed ~is much higher since shear action engages.all studs.
Also note that the analysis prepared during the investigation of these anchors shows that the actual imposed loads on these plates are lower than the calculated design capacity.
We will be prepared to discuss these responses with you in our meeting May 29.
Very truly yours, j,i lN j 'l, / /
)
5.1f.- % 4 ' g - 6 61 - O v s Donald F.
Schnell Manager - Nuclear Engineering i
1 l
t w
r.
i 134 / otsics cr stw st:!Lotscs size in any length of six times the effectise throat or weld be acceptable if they meet the reqv;rements of Table size. When the length of the weld being examined is less 8.15.3. Ultrascrically tested welds are esaluated on the than six times the effective throat or weld size. the per-basis of a discontinuity reDeering ultrsound in propor-missible sum of the greatest dimensions shall be propor-tion to its effect on the ir.tegr'ty of the we!d.
tionallv less than the effective throat or we!J size.
'(b) The space between two such discontinuities 8.15.4 Ligt:Id Penetrant Inspection. Welds that are which are adjacent is less than three times the great-subject t liquid penetrant testiqg, in addition to sisual est dimensian of the larger of the discontinuities in the inspection, shall be evalusted on the basis of the require.
pair tv.ng considered, ments for visualinspection.
8.15.2.2 Independent of the requirements of 8.15.2.1, 8.15.5 When welds are subject to nondestructive testing discontinuities having a greatest dimension of less than in accordance with 8.15.2, S.15.3, and S.15.4, the test.
3/32 in. (2.4 mm),if the sum of their greatest dimensions ing may begin immediately after the ccmpleted we!ds exceed 3/8 in. (9.5 mm)in any linear inch of weld.
hase cooled to ambient temperature. Accep:ar.ce critena for ASTM A514 ar.d A517 stee!5 shall be based on non-8.15.3 Ultrasonic Inspection. Welds that are subject to desttuctise testing performed not less than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> after ultrasonic testing, in addition to visual inspectior.. shall comp! tion of the welds.
0 08 g
g 0.07
-g No ca!cula:ed stress
/
L I
I i
t,. 'S 125 f.
(L '61
/
,l 0.C5 f
7-
/
Primary Tensile Stress 0.04 j
7 g
f Paratief t: neercut; shear. conrespon in g
g j
/
any directron j
0 C3 7[.
l D
e I
'e Primary Tensife Stress f
j j
0 02 Tranr,erse to uncercut 0.01
.i i
l !
gga 1
2 3
4 5
6
)
A3 Memt.er thickness, in, ff z.
Fig. 8.15.1.5-Permissible undercut values for buildings Y
3, t!
2 k l o
i' h
4
- A alMm e'
t s
p 9h L ~ -, m.~. m, w w. m.: x m. w w. m.~~t w m. m n W 5 D #d-M:
ATTACHMENT "B" Plates with multiple failed studs A 115 - 214 (EP 912D)*
A 114 - 39 A 114 - 170 A 114 - 29 A 115 - 34 (EP 912D)*
A 115 - 251 (EP.912D)*
A 115 - 62 A 115 - 457 i
A 116 - 35 (EP 812A)*
A 103 - 43
- These plates had 2 failed studs in a four stud cluster.
I f
a l
.,,,.,,.-.m-J
.)
i EMBEDS WITH DEFECTIVE AND FAILED STUDS Number of Number of Type of Embed Piece Mark Defective Studs Failed Studs Non-Q Sleeves A96 1
1 A98 3
3 A98 3
3 A100 1
1 A98 1
1 Non-Q Sleeves E5031-A73 1
0 F5027-A26 2
2 3052-A30 2
2 E5053-A47 1
1 Plates with A127-8 1
1 Machine Welded A127-25 1
0 Studs A127-26 1
0 A127-27 2
0 A115-214 3
3* -
All5-216 2
0 A114-134 1
0 All4-396 1
0 A114-29 2
2*
All5-152 1
1 A115-67 2
0 A115-72 4
0 All5-69 1
1 A127-55 5
0 A127-466 1
0 A127-15 3
0 A127-14 4
0 A127-13 4
0 A115-126 7
0 All5-310 2
0 All5-133 5
0 A115-134 6
0 All5-130 7
0 A115-281 1
0 All5-280 1
0 A115-112 8
0 All5-25 1
0 A115-114 7
0 l
A115-115 5
0 i
I A115-290 6
0 All5-73 1
0 A115-131 8
0 l
A115-132 7
. O A115-135 7
0 1
O All5-22.
7 0
All5-277 1
A115-276 5
0 A115-124 5
0 A115-105 8
0 A115-118 7
0 A115-108 7
0 i
ATTACHMENT "C'>
t/U3M Pictco with A115-64 1
0 Machine Welded All5-294 4
0 S tuds A115-342 1
0 A115-274 7
0 A127-184 3
0 A127-156 1
0 A127-330 1
0 A115-34 2
2*
0 A115-35 4
A115-1 2
0 A115-270 4
0 All5-136 8
0 All5-116 4
0 All5-123 8
0 A115-23 7
0 A115-80 1
1 A115-101 1
1 A115-106 10 0
A115-107 6
0 A115-127 9
0 A115-128 8
0 A115-16 1
0 A115-106 8
0 All5-129 6
0 A115-337 1
0 A115-122 4
0 A115-117 5
0 All5-109 6
0 A115-110 6
0 A115-20 1
1 A115-46 1
0 All5-159 1
1 A115-168 1
1 A115-251 2
2*
A115-275 9
0 All5-121 5
0 A115-120 6
0 A127-121 1
0 A127-120 1
0 A127-112 1
0 A127-118 2
0 Door Frmnes A818 11 3
A816 2
0 A806-5 1
1 A806-6 2
2 Angle Frc.=es AS41-6 1
0 AS42-5 1
1 AS42-4 1
0 AS42-8 1
0 A570-1 1
0 A526-14 1
0 A526-12 1
0 A568-4 1
0 A568-2 1
0 A568-7 2
0
ATTACEiENT "C"
_ Pag') 3 of 3 Angla Frameo A568-8 1
0 AS43-6 2
0 AS43-10 2
0 A543-13 1
0 AS43-7 1
0 A543-12 1
0 A543-8 1
0 Plates with A114-198 1
1 5
O Machine Welded G108-2 Studs A108-3 3
0 A108-5 2
0 A108-6 3
1 G108-7 2
0 G108-6 1
0 G108-8 1
0 All5-198 1
1 A115-203 1
1 All5-202 1
1 All5-62 2
2*
All5-65 1
1 A115-307 1
1 A115-457 2
2*
A115-456 1
1 G108-10 2
0 A108-1 8
0 G108-14 10 0
All4-171 1
1 All4-173 1
1 A114-158 1
1 A261-14 1
0 A261-431 1
0 A261-454 1
0 A261-391 1
0 A261-16 1
0 A231-7 1
0 A231-4 1
0 A231-3 1
0 A114-145 2
0 All4-71 1
0 All4-67 1
0 All4-90 1
0 A114-146 1
0 All4-119 4
0 A114-92 4
0 A167-36 2
0 A167-414 1
1 A167-234 1
1 A162-377 2
1 A116-35 2
2*
A162-190 1
- 1 A113-10 3
O A123-22 1
0 A123-13 1
0 A123-20 1
0 A123-29 1
0 A103-43 5
3*
~V W
6 ja
- Plate with multiple failed studs (10)
TOTAL UNITS INSPECTED 7543
Attr_chment "D"
's DANIEL INTERNATIONAL CORPORATION CALi.AWAY PLANT j
,j*
P. o. sox ice FULTON. MISSOURI 65251
.. u.n...
May 22, 1980 DLUC-5407 No Response Required Union Electric Com.pany P. O. Sc.c 143 (Code 470)
St. Louis, Missouri 63166 Attention:
Mr. W. H. Weber Manager, Nuclear Construction
Subject:
Fasponse to UTD 6936, Item 16 - "NRC Questions on UE Embed Report - Callaway Plant" Paference:
ELUC-990(Attched)
SLU 6-41 SLBM 6-514
Dear Walt:
The subject UTD (Item 16) raises questions regarding the actions taken as a result of SLU 6-41 and SLBM 6-514.
These letters indicated that Cives was allegedly not in control of production quality based on Bechtel/SNUPPS inspecticn findings.
As a result, DIC performed an inspection of 10% of the Cives embeds supplied prior to 11/15/76.
The results of this inspection were docu ented via DLUC-990 (Attached).
Sho:,ld you have further questions in this regard, please do not hesitate to contact the writer.
Very truly yours,
/dW Y
- y. z;5 - g-o W
H. J. Starr Project Manager rY h HJS:E QCJJ:5.T:hes Attach.er.t:
DLUC-990 CC:
E. C. McFarland (6)
K. i:JeChanmeister (advance Copy)
M. M. S-ith B. C. Tye File (Ali.56)
D If Y A o
_g LF o m
. S.1
=2 e
~2M= =9
T. r..
CANIEL IN' ER.ATIONAL CORPORATION CAL.AWAY PLANT P. O. ecx los FJ TCN. f/JS50URI 65251 ts t 4 3 c7 c.31 s t
~
- ecenber 3, 1976 DLUC - 990 LC.3n J.:.ecO!!.C CoCpany P. O. Icx 149 St. L: f.s, l'issouri 63166 Atten:ien:
Walter H. Eeber Y.anager, Nuclear Constructi6n Subj e:::
F.iscellaneous Steel Specification C-131
Reference:
SLU: 6-41 Telecon S. J. S. eiken of 11/2/76
_v e r.:
- z. e -
In accordance with the referenced requests, we have cc placed an inspection of miscellaneous steel shipped to tLe proj e:: f cm the Cives Corporhtion as indicated by the Coll a-ing tebulation:
N -her of pieces received at project to 11/15/76... 3740 n -h er cf p ieces ins p ect e d.........................
37 4 Di5crep C.cLes.......................................
4
~
'?isce I?-312-A126-5 (D.:g. C-0012-Q)
<.e:c undercut
?iece I?-all-A10-43
..e..le unoercut
?iece I?-614-A814 1.eldundercu:,visibleslagandincompleteweld Pie:s I?-912-D-A115-165 Cefective veld on stud
- jgn::nf:-.ance rep:::s have been initiated for the four
- _:.:ep.n: p:.e es.
h...-
D @ @'D
? DlW n
.c.r-.'.M bJ 1apw L}..
-.C.Qk 5
3
.e..u u....r
.%)'J * ' *
' s a ti:d ^
3',
1976
, -=$=
- r. tier :
the aboce findings, we conclude that uncertain-
- .e s I:: r i s s e. : :.n t..e re:erenced SLU:6-41 are ur. founded, and
- ..e
.t: gr-,._._.._,.a_ coes 2.n :act achere to the standard of quality Very truly yours, 7^,
M. R. Hamby, Jr.
Project Manager
- v. =_:.,
- ?n _
cc:
L. Earsen.
. 1: eld D'.
Schnell S.
Seiken W. van der Zalm D
D""D
~T } g
- 1. br u%
oo a-4
.