ML20107K416
| ML20107K416 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/25/1985 |
| From: | Ellis J Citizens Association for Sound Energy |
| To: | Atomic Safety and Licensing Board Panel |
| References | |
| CON-#185-780 OL, NUDOCS 8502280268 | |
| Download: ML20107K416 (26) | |
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lj 26fp/gfED UNITED STATES OF AMERICA 3
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- NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD
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In the Matter of I
l Docket No SF TEXAS UTILITIES ELECTRIC 1
O 5
COMPANY, et al.
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(Applica'tichtfor.,an Operating.,Licehse) m:.%qg, '
s (Comanche Peak Steam Electric l
s.-
Station, Units 1 and 2)
Q A.--4. L.. l' ti NOTIFICATION OF NEW AND SIGNIFICANT INFOPJfATION AND CASE'S SUPPLEMENT TO CASE'S 10/15/84 MOTIONS AND ANSWER TO APPLICANTS' MOTION FOR
SUMMARY
DISPOSITION REGARDING STABILITY OF PIPE SUPPORTS
./
Pursuant to the Board's 10/31/84 Memorandum (Multiple Filings), CASE (Citizens Association for Sound Energy), Intervenor herein, files this, its Notification of New and Significant Information and CASE.'s Supplement to CASE's 10/15/84 Motions and Answer to Applicants' Motion for Summary Disposition Regarding Stability of Pipe Supports.
CASE's 2/25/85 Supplement consists of the attached Cygna letter 84042.035 dated February 19, 1985, from Ms. Nancy Williams, Cygna Project Manager, to Joe George, TUGC0 Project General Manager.
(Also attached are some recent applicable newspaper articles.)
Cygna's letter represents a complete change of Cygna's original position on the issue of stability, and supports the testimony of CASE i
Witnesses Jack Doyle and Mark Walsh, the statements made on this issue in CASE's 8/22/83 Proposed Findings of Fact (Walsh/Doyle Allegations) (Sections III and IV), as well as CASE's 10/15/84 Answer to Applicants' Motion for Summary Disposition.
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With' regard to the four criteria set forth in the Board's 10/31/84
~ Memorandum (Multiple Filings) for supplementing answers to Motions for Summary Disposition, CASE offers the following:
(1) Relevance: 'The subject of Cygna's letter is " Stability of Pipe Supports," and it is directly relevant and material to this issue.
(2) What new material in the-last round filing is being responded to:
As discussed in more detail.in the following, this is new and significant ipormationwhichsupplementsCASE'spreviouspleadings.
(3) Why the party was unable to anticipate this material in its last.
filing:.0bviously CASE could not have anticipated Cygna's change of position-regarding this issue.
(4) The safety significance of the point that is being made. As has been discussed previously, the safety significance is well-established; this
-is one of the! specific issues chosen by Applicants to attempt to prove, in response to the Board's 12/28/83 Memorandum and Order (Quality Assurance for -
Design), that the design of the entire plant is adequate and safe.
As is obvious' from'a reading of Cygna's letter, Cygna has now verified CASE's concerns and conclusions regarding the issue of stability.
(it should also be noted that the letter contains information which also applies to other issues which overlap with the issue of stability, such as local
' displacements and' stresses, cinched-down U-bolts, etc.)
i Applicants provided Cygna with a copy of the 6/17/84 Affidavit of John C. Finneran Jr. regarding Stability of Pipe Supports and Piping Systems (listed as reference (3) in Cygna's letter); this is the same Affidavit l
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which 'was. attached to Applicants' 6/17/84 Motion for Summary Disposition Regarding Stability of Pipe Supports. Since Cygna has specifically addressed and' referenced portions of Applicants' Affidavit, we believe the Cygna letter is'self-explanatory and can be easily correlated with Mr. Finneran's Affidavit attached to Applicants' Motion for Summary
~ Disposition and CASE's response.
While Cygna's entire letter is instructive, we refer the Board especially to the following cross-referenced items which have been specifically. discussed by Cygna:
' System Stability vs. Individua1' Support Stability:
Cygna letter, pages 4 and 5, " System Stability," and page 5,
" Commentary on TUGCO's Position" Finneran Affidavit, pages 2 through 8 Applicants' Statement of Material Facts: statements 1, 2, and 3 Case's Answer to Applicants' Statement of Material Facts: pages 1 through 8 Cygna has confirmed the concerns raised by CASE Witnesses Jack Doyle and Mark Walsh, and specifically addresses Applicants' first Statement of Material Facts, referencing Finneran Affidavit at pages 5-7, where Applicants state
" Instability of a particular pipe. support, when viewed in isolation from the piping system, is of little or no significance. The relevant consideration is whether the entire piping system and associated supports are stable when considered as a single system."
Cygna states
.Page 4:
"If individual support stability is not assured, system stability is not guaranteed. The instability of one support can trigger the progressive instability of adjacent supports 3
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.by causing the limits of the forces and displacements to which the adjacent supports were originally designed to be exceeded. This may result in the formation of plastic hinges in the pipe (due to overload} which in turn may develop into l
a collapse mechanism. This situation would not, however, prevent successful execution of a linear, elastic pipe stress computer analysis."
Page 5:
"... the issue is not piping system stability, but rather the stability of the individual support itself. The key point is whether the individual support can resist the applied load within the initial eccentricities and displacement limits imposed upon it."
Box Frames With Single Struts or Snubbers:
Cygna letter, page 6, first and second paragraphs (box frames with zero-inch gap attached to a single strut or snubber; and Applicants' fixes)
Finneran Affidavit, pages 9 through 13-Applicants' Statement of Material Facts: statement 5 CASE's Answer to Applicants' Statement of Material Facts: pages 18 through 20 Cygna has confirmed the Walsh/Doyle concerns and stated "Cygna classifies these supports, without modification, as unstable." Further, Cygna found that two of the three fixes utilized by Applicants to modify this type of supports to improve their stability " result in supports which must still be classified as unstable," and the third fix (cinching down of U-bolts) remains an open issue at this time.
U-Bolts. Single Struts, and Thermal Cape Cygna letter, last paragraph on page 6 continued top of page 7 (single struts with U-bolts and a thermal gap; and Applicants' fixes)
Finneran Affidavit, pages 15 through 18 Applicants' Statement of Material Facts: statements 7 and 8 CASE's~ Answer to Applicants' Statement of Material Facts: pages 27 through 43 4
Cygna has confirmed the Walsh/Doyle concerns and stated "Cygna classifies all single struts with U-bolts and a theran1 gap
... as unstable.
Cygna also found that one of the two fixes utilized by Applicants to modify this type of supports was
" unacceptable," and the other fix (cinching down the U-bolts) remains open.
Double Strutted Frames:
Cygna letter, first full paragraph on page 7 (double strutted frames supporting a single pipe and double strutted trapeze supports with uncinched U-bolts); and second full paragraph on page 7 (double strutted trapeze supports with cinched U-bolts)
Finneran Affidavit, pagea 19 through 21 Applicants' Statement of Material Facts: statement 9 CASE's Answer to Applicants' Statement of Material Facts: pages 44 through 49 Cygna has confirmed the Walsh/Doyle concerns and stated that Cygna classifies these support configurations as unstable.
Single Struts or Snubbers with Snur U-bolts:
Cygna letter, third full paragraph on page 7 (single strut or snubber with a cinched U-bolt)
Finneran Affidavit, page 21 Applicants' Statement of Material Facts: statement 9 CASE's Answer to Applicants' Statement of Material Facts: pages 44 through 49 Cygna has confirmed the Walsh/Doyle concerns and stated that until the issue of U-bolts used as pipe clamps (cinching down of U-bolts) is resolved, Cygna classifies this support configuration to be unstable.
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I Number of Unstable Supports:
Cygna letter, " Classification of Cygna Review Scope," last paragraph on page 7 continued on page 8 Finneran Affidavit, pages 21 and 22
. Applicants' Statement of Material Facts: statements 10 and 11 CASE's Answer to Applicants' Statement of Material Facts: pages 49 through 54
~ Applicants stated that a total of 27 safety-related supports for all Unit 1 and common areas were potentially unstable, and that this figure is concistent with Mr. Finneran's representation to the Board in an af fidavit fil'ed June 3,1983, that only 21 of 13,681 supports certified at that time had been identified as potentially unstable.
(It is important to remember that neither Applicants nor Cygna have addressed potentially unstable supports in Unit 2.)
Cygna has stated that 65 supports out of the 226 which they looked at are potentially unstable.
(See further discussion on pages 7 and 8 following.)
There are a few additional comments which are appropriate at this time. First, it should be noted that Cygna now agrees with Messrs. Doyle and Walsh and disagrees with one of Applicants' basic premises regarding instability; Cygna addresses what was stated in Applicants' first Statement of Material Facts, referencing Finneran Affidavit at pages 5-7:
" Instability of a particular pipe support, when viewed in isolation from the piping system, is of little or no significand.e. The relevant q
consideration is whether the entire piping system and associated supports are stable when considered as a single system."
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In fact, Cygna specifically states:
Page 4:
"If individual support stability is not assured, system stability is not guaranteed. The instability of one support can trigger the progressive instability of adjacent supports by causing the limits of the forces and displacements to which the adjacent supports were originally designed to be exceeded. This may result in the formation of plastic hinges in the pipe (due to overload) which in turn may develop into a collapse mechanism. This situation would not, however, prevent successful execution of a linear, elastic pipe stress computer analysis."
Page 5:
"... the issue is not piping system stability, but rather the stability of the individual support itself. The key point is whether the individual support can resist the applied load within the initial eccentricities and displacement limits imposed upon it."
Cygna has also confirmed what CASE has been saying:
that many of these types of supports are unstable or potentially unstable (contrary to 4
Applicants' assertions). The magnitude of the problem is readily apparent, even using simple arithmetic. Applicants stated (pages 21 and 22 of Finneran Affidavit) that a total of 27 safety-related supports for all Unit 1 and common areas were potentially unstable, and that this figure is consistent with Mr. Finneran's representation to the Board in an affidavit filed June 3, 1983, that only 21 of 13,681 supports certified at that time had been identified as potentially unstable.
(It is important to remember that neither Applicants nor Cygna have addressed potentially unstable supports in Unit 2.)
However, the 65 supports which Cygna states are "potentially unstable" equal 29% of the 226 supports reviewed by Cygna; this translates into 11,600 (of the approximately 40,000 supports at Comanche 7
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. a-Peak) which.are potentially unstable, if Cygna's sample were representative.
- (And it should be noted that Cygna's Ms. Nancy Williams believes Cygna's sample is " fairly representative," according to public statements; see atta'ched-2/21/85 DALLAS MORNING NEWS article). Even'if one were to accept the suggestion by' Texas Utilities spokesman Dick Ramsey-(see attached 2/21/85; DALLAS MORNING NEWS article) that "48 ' unstable' supports could-be reclassified as stable if Cygna's ongoing analysis finds the supports acceptable," the remaining 17 represent 8% of the 226 supports reviewed by Cygna; this translates into 3,200 supports (out of the approximately 40,000 supports at Comanche Peak) which apparently are unstable, if Cygna's sample
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were representative. Although these obviously are not firm figures and
-Cygna's sample may.not in fact be representative _(although if it is not, the Cygna Reports could not have resolved the Board's concerns about design issues), one thing is now apparent -- contrary to Applicants' representations to the Licensing Board,lthere is a much more severe and widespread problem regarding unstable pipe supports at Comanche Peak than.-
Applicants have ever recognized or admitted.
In Applicants' Statement of Material Facts.(statements' 4, 5, 6, 7, 8,
'll, and 15) and in Mr. Finneran's' Affidavit (pages 9-18, 26-29), Applicants
. sought'to convince the Board that they had promptly identitied and corrected all unstable supports, and that there was no need for separate design f
guidelines regarding stability (see also CASE's Answer to Applicants' Statement of Material Facts, pages 8-43, 50-54, and 58-59). - Cygna's
~ findings refute Applicants' representations, since some potentially unstable supports went through the entire design review cycle -- including review and approval by the responsible design organization -- without having beer 8
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p identified as potentially unstable (see pages 14 and 18 of Finneran Affidavit; see also Cygna letter, especially page 6, second and this paragraphs, which addresses fixes by Applicants which resulted in supports which were still unstable).
' Applicants also sought to convince the Board that "The conditions which could cause instability of the supports in question are unlikely to occur" (Applicants' Material Fact 13, Finneran Affidavit at 24; see also CASE's Answer to Applicants' Statement of Material Facts, page 55). Obviously, Cygna's letter refutes this-representation of Applicants.
Further, Applicants sought to convince the Board that there is no r
safety concern because of the potentially unstable supports '(Applicants'.
1,
' Material Fact 11, Finneran Affidavit at 19-21, 9-18, and 27-28; see_also CASE's Answer to Applicants' Statement of Material Facts, pages 50-54, 58-59). This is specifically refuted by Cygna's statements at the bottom of page 4 continued on page 5, where Cygna discusses the importance of assuring f
individual support stability and that: individual unstable supports may lead,.. s -
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to developments which may result in a collapse mechanism.
i Cygna's letter is of special importance because it represents independent verification of the position of CASE and its witnesses, Jack,
DoyleandMarkWalsh,bytheoutsideconsultantchosenbyIpplicants a list of all the themselves. Cygna has stated that it does not have:
Walsh/Doyle allegations or a full understanding of the extent or implications of each of the allegations, any of the transcripts of hearings 9
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priortoFebruary11984,anyfindingsof_ fact /,1/, CASE'sresponsesto 2 Applicants'. Motion for' Summary Disposition or other CASE documents (see transcript pages 15,'37-49, 67-76, and 105-167 of the 12/20/84 meeting
- between Cygna and the NRC Staff regarding Independent Assessment Program -
a Comanche-Peak Steam Electric Station).
CASE again calls the Board's attention to the discussions in our 10/15/84 Motions.and Answer to Applicants' Motion for Summary Disposition Regarding Stability of Pipe Supports, especially pages 11 and 12:
" CASE further submits that, based on the record in these proceedings
'(including the Motions for Summary Disposition and answers), the-
. problem of instability at Comanche Peak is one which Applicants have been slow;to recognize and which they have, in fact, fought hard against being forced.to recognize and deal with, that they are even now
' finally taking steps to deal with some. aspects of the problem only-lbecause of these proceedings, and that the preponderance of evidence clearly shows that Applicants would not have corrected these problems-of instability'had it not been for the oversight of the Licensing Board and the persistence of Messrs. Walsh and Doyle and CASE in these
, proceedings;.and that, even now, Applicants are attempting to avoid-
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. dealing with some' types of instability.
1 "The: Board discussed the problem of-instability at'some length in its
'12/28/83 Memorandum ~and prder.(Quality Assurance'for Design). The Board gave Applicants another opportunity to allow them-to salvage
'their multibillion' dollar investment. -This (and other~ Motions for Summary Disposition) was that chance. But what has been, and is being, revealed-is that'the Board's original concerns were not quite= accurate
-- because:the problems with stability _(and.others) are far more severe
'and widespread than.the Board (and'even CASE) had first' imagined."-
(Emphases-in.the original.)
~_-]1/f -It. should be _noted, however, that to CASE's knowledge - Cygna at' one. time s
~.did'have a-copy of CASE's 8/22/83 Proposed Findings of Fact E(Walsh/Doyle Allegations).: CASE President Juanita'Ellis personally hand-delivered =a copy to Cygna during the-February 1984 hearings; CASE-jWitness. Jack Doyle-also' recalls that Mrs. Ellis gave Cygna a copy.
JCygna'kept.the copy for a while, then mailed it back to CASE.
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Cygna's letter further confirms that CASE's assessment quoted above, and the conclusions in the Board's 12/28/83 Memorandum and Order, were and still are correct.
Further, there is still no indication that the "sonewhat knowledgeable" field engineers (on which Applicants have attempted to place much of the blame for unstable pipe supports at Comanche Peak)'are not still in the field making the same mistakes they made in the past.
Cygna's letter now also calls into question the credibility aad/or competence of those engineers who were in charge of those "somewhat knowledgeable" field engineers, as well as the original designers who, even af ter final reviews, did not even recognize that some of the supports were potentially unstable.
It should also be noted that there is no indication as of this writing (either in, or outside of, the record of these proceedings) that Applicants have changed their position regarding stability; they are still refusing to admit (for the most part) that the problem even exists, much less the magnitude of the problem (see public comments by Applicants' representatives in the attached newspaper articles).
Applicants have fought long and hard to convince the Licensing Board that.there is no problem with unstable pipe supports at Comanche Peak.
~
When they finally were forced to admit that there were some potentially unstable supports, they attempted to downplay and underestimate the extent of the problem (both in numbers and types). This latest new and significant information from'Cygna further calls into question the design of the entire rest of the plant. There is no reason to believe that Applicants have l
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identified and/or dealt with other design problems any better than they have with the problem of instability of pipe supports.
Finally, CASE wants to make the Board aware that we believe that there is currently a move afoot to dump Cygna and sweep the design / design OA issues (along with the hardware / construction problems) right out of the hearings process, to be considered by the Applicants and NRC Staff without proper independence criteria, or scrutiny from the Licensing Board, CASE or the public, or adequate control and oversight. CASE opposes any such attempts to subvert -the consideration of these important issues, which are part of a duly-accepted contention in these operating license proceedings and must therefore be considered by the Atomic Safety and Licensing Board.
We will be discussing this in more detai1~in a pleading which we are currently working on regarding Cygna, dcsign/ design OA issues, and other aspects of the proceedings; we hope to have this pleading in the-mail within the next week or two.
Respectfully submitted, Rd Ea2 p s.) Juanita Ellis, President CASE (Citizens Association for Sound Energy) 1426 S. Polk Dallas, Texas 75224
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THURSDAY. FEBRUARY 21.1985 5 Scetions 25 Cents Consultant raises doubts Comanche consultant reverses report
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CMIANCIIE - Froro Page One through additional studies.
one support would be unimpor.
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- It sounds I:ke they're quotmg tant if surroundmg supports were p *3M p
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pr mtery fer the Cauren. Awn. me nght down the hne." Doyle sound. 'Ihr report said anstabihty l!
V kb et r.n ser Sound Ernrgv. a Dallas said after readmg the new Cygna in one support could cause a cham eWidmierest group that raned report It's nell estabhshed now reaction leadmg to failure of a th.: the supports are unstable, row of supports.
""' L'pe support issues more inan By JACK EOOTH supports were stable, had asxed supports are c:ther unstab!e or " mea s ago.
That is not to say that they can't Another important fmdmg. Chs Staff %.nter
.s. Atomic Safety and ! i. quesuonable. A spot chak of 225 Amciation President Juanita be fixed. but it's going to cost said, was that some of the I
une end supports turned up 65. or 29 per. Elhs said the report confirmed a enem a buck or two."
attempts by the utzhty to fax un.
The owners of the Comarche Ehis saad hundreds or even stable supports had failed,and the two ears !
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t *em p tentially unsta.. key abegation raued by two for.
Peak nuenear plant suffered a raa.
is and dec leuer said.
mer plant design engineers. blark thousands of supports may be repairs thwnselves were unstable.
Jor setback Wednesday when a But in
"' P 8' Texas Utahues spokestnan Dick Walsh and Jack Doyle. Initial tes. questionable if Cygna's sample of Rarnsey, said he could not esti.
consultant raised doubts about the leased Wed safety of eig.t types of ppe sup. has changed its p'sinon and now Ranuey said he d J not know how time ny by the pair prompted the 026 supports is reprerentative of many of the plant's.lc l.censm; board m Deecmber 1933 the plant as a whole.
i the results of new studies of ppe ports at the plant.
pany und in sts supports are aflected'W to rule that the safety of the She said a major finding of the support problerns. Those studies The fmdines by Cygna Energy g [ter by he As a resul mport.
plant's desgn was in doubt and report was that the natihty was are being conducted by one of Servues could cause lengthy de.
w uld have to be confirrned wrong in arguing that a defect in several consulting teams.
He said studies now under way..
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'r p ssitmhty exists a a
es h p pm steel suppods could co!!apsc. caus. truid resolve many of the oues.-
out a qukk %. O Pp 8UP. ing pigs full of radmactive cool tions, but he conmded the repcet' port issues.
ant bmak and whip around hke contradets some of the statements; Texas Unlities b.e'Co I
g.[a then th nsi g its nsu tan e
e report said eight types of See CollANCIIE on Page 8
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Da!!as, Texas, Thursday, February 21, 1985 H3 25 Cents m
- i. mg Pipe supports at X plant Aw
,ounc notentially unstac, le w
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4 A Cygna Energy Semces #attee A;.
concerrung a revven of pce sup.
por't t the Comanche Peau nu-By Datid Real platt'8 pipe supports pon ia21s.
crear plant said:
3,g,,,,, m y,,.
The engineers' concerns' The supports are needed to ketP procipted htu Bloch. chairman of trghly pr u rized pipa frorn E That 23 percent, or 65 cl 226 More than a qua ter of 226 pipe the the Atomic Safety and bcensing breahng apan during unbpam p'p* 1 5 80poo'ts... esammed.
scpports inspected by an scdepend.
B ard, to declare an late 1983 that or fra:e ahapping around out of apoeared to t>e unstatwo... e e...
ect design consultant at the Coman-the" record before us castsdoubt cn controland canstng more damage af a That the study samples are not che peak nuclear power plant are the design qualzty" of Comanche a pipe breaks during plant opera-dissarrdar to other pope supports potentully trustable and require a ame plant s owan. Texas Uttk tsoa en the plant plantwsde review to rule out the ities, ordereJ the Cygna audit on A special Nuclear Regulatory pcssibility of a domin&!ike collapse a That 7frorn a pract. cat stand-Bloch's recommendation Commission task force is scheduled of the piping system, officials of to review prpe supports with utility 4
peant7 rr.any of I e potentiap un-y Cygna Energy Services of San Fran.
Cygna's comments were con-ofte at Comance Wak Tn@y ststdo designs rnay actuaPy per.
form the.r erstended funct.on.
casco said Wednesday.
tained in a letter that recommends and Wednesday
- The findings support one of the that the attisfy evaluate pipe sup-
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E criticisms leveled almost three ports throughout the plant and en-
,,,g"[h detin he o p years ago by two former Comanche ther modify the supports to solve m ufp stanty - m
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,,; g,,ng hak engineers, Jack Doyle and the problem or prove that each sup-ports that 29 percent, or 65 of 226 3
g, Mark Welsh, who questioned the port ts stable or that the entire syv Tae DanM:creat hem-adequacy of the design of the -tem is stable if any individual sup. Please see CO*.tANCf!E on l' age II A.
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Comanche Peak pipe supports found potentially unstable " l
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"I thsok we have a fa!rly repre-snight have on the plant cost and h
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. steam system.
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Crittsued from Pare 3 A.
function."the report stated.
T2pe sr.ppo-ts examined, ap' eared Ramsey said the study sample's
- ! dont think they're going to sentativesample."she ssid.
v ta be'usstable.
pt:v support problems are net nec-end up baving to go back in the She said Cygna is concerned that Doyle said be felt vindacated by rp the report.
Cottlanche Peak qg However. Texas 17taht:cs spokes essanly representative of all pipe plant and fix 3 percent of their during the Itfe cf the plant, a ptre man Dick Ramsey sa2d thr.1 the re. systems in the p! ant.
supports becaura they cani guaran-may move and relate a pire support "We ve been waiting three years n
Plant g
But Nancy Wilhams. Cy;;na tee positive connectio:a." she said. clamp to the extent that the p;pe for this day." Doyle said. "This par.
supports could be ree!:ssified as protect manager for the Comanche "I think they have to carefully look support may not function as engl-tscular
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port concedes that 45 castaMe" other areas there is considerable e,ger, i
e Peak pipe support review. said the at all the supports they have and nally designed.
"We think that some of these doubt about the validity of the utt!-
Rose' stiblef tf Cygna s ongo:ct analysis study sampfes are not dissimilar to ' come up with a realistic and technn-
"Cygna recognizes trert a practi-other ptpe supports in the p! ant. cal!y correct assessment as to pipe supports are clearty nnstable.- sty's experts."
Ett Wi!!sams said the Cygna find-though more analyticalwork needs findsihe supports acceptable.
poten' sally uns able designs may m:ned are part cf the component Now, how many that is. I don 1 Ramsey said that be could not es-sags venfy some of the concerns to be done to confirm or deny the which ones need to be modalled. Ets. Wilhams said.
cat standpo:nt that many of these She said the pire' supports eta-actually perform their intended coohng water rysteattand tbe matn know..
timate what impact the report raised by Walsh and Doyle. al _ concerns _ --
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&.2 101 California Street, Suite 1000. San Francisco, CA 94111-5894 415.397 5600 February 19, 1985 84042.035 Mr. J. B. George Project General Manager Texas Utilities Generating Company Conanche Peak Steam Electric Station i
Highway FM 201 Glen Rose, Texas 76043
Subject:
Stability of Pipe Supports Texas Utilities Generating Company Comanche Peak Steam Electric Station Independent Assessment Program Job No. 84042
References:
(1)
N.H. Williams (Cygna) letter to V. Noonan (U.S. NRC),
"Open Items Associated with Walsh/Doyle Allegations,"
84042.22, dated January 18, 1985.
(2)
N.H. Williams (Cygna) letter to V. Noonan (U.S. NRC),
" Revision to Open Items Schedule," 84056.055, February 14, 1985.
(3) Affidavit of John C. Finneran Jr. regarding Stability of Pipe Supports and Piping Systems, dated June 17, 1984.
(4) Cygna Phase 3 Final Report TR-84042-1, Rev. 1, November i
20, 1984.
Dear Mr. George:
As committed to in Reference 1 and subsequently revised in Reference 2, Cygna has completed an evaluation of the pipe support stability issue.
This evalua-tion considered the support designs reviewed by Cygna as part of Phases 2, 3 and 4 as well as TUGCO's position described in Reference 3.
Since stability is a very complex issue, we will sunmarize our position in six parts:
(1) Definition of Stability, (2) Dynamic Versus Static Stability. (3) System Stability, (4)
Commentary on TUGC0's Position, (5) Classification of Cygna Review Scope, and (6) Conclusions.
San Francisco Boston Chicago Richland
=
Mr. J. B. George February 19, 1985 Page 2 Definition of Stability Prior to performing an evaluation of this issue, criteria were developed to define what constitutes an unstable pipe support.
Individual pipe supports can be classified into two broad categories:
(1) supports which, in the total abser:ce of the pipe, are stable, and (2) supports which, in the total absence of the pipe, are unstable.
Implicit in our definition for the second category is the fact that the instability is a rigid body type which may be completely removed or accommodated by proper attachment to the pipe. That is, by restrain-ing certain degrees of freedom at the attachment to the pipe, such as with a pipe clamp, the instability nay be removed. Alternatively, by limiting the motion following instability through the presence of the pipe and adjacent supports, the instability nay also be eliminated. Since there is no stability issue with respect to supports of the first category, only supports of the second category need be discussed.
In order for a support of the second category to be stable, there are two requirements to be met, one involving force transfer between the pipe and support and the other involving the geometric relationship between the pipe and support. The force requirement is met if adequate forces, which develop instantaneously and can be relied upon by design, exist between the pipe and the support hardware to resist the factored load. The following definitions are provided for clarity:
develop instantaneously (immediately): Resisting forces are e
activated at the same instant that piping loads are applied. An example of forces which cannot develop inanediately are binding forces which require a rigid body motion of the support (rotation, translation) to become effective.
by design: The mechanism for and magnitude of the resisting forces are calculatable and known, or have been evaluated exten-i sively by test or by use in the specific application.
factored load: Applied load times a safety factor.
In addition to the above described force requirement, the geometric relationship between the support and the pipe must remain within set limits during the i
operational life of the plant.
If sufficient clamping forces between the pipe and support are not present, small pipe movements nay cause large changes in the position of the support relative to the pipe. Piping system vibration occurring during start-up, normal operation or shut-down can cause the support to move (rotate, translate) relative to the pipe. This support movement is unfavorable if, for a support initially perpendicu.lar to the pipe, the direction of pipe
9 seevers Mr. J. B. George February 19, 1985 Page 3 movement in the absence of the support is such that the displaced centerline of the pipe intersects the arc made by the rigid body motion of the pipe center within the support. The new position of the support on the pipe nay be well outside the displacement (eccentricity) envelope for which it was designed and for which stability has been assured. Since the support did not restrain the movement of the pipe during this process, adjacent supports must now resist an
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additional load for which they my not be adequate. Therefore, a sufficient condition for individual pipe support stabili.ty of the second category is a design in which, upon the application of the factored load from the pipe, adequate resisting forces can be developed immediately and the position of the support attachment on the pipe does not move relative to the pipe with time.
Considering the definition presented above, we will now discuss some specialized situations in which the instantaneous development of resisting forces required for stability does not occur. For these designs momentary instability (of the rigid body type) could be tolerated, provided that it can be demonstrated that sufficient forces eventually develop to completely remove the instability (i.e.,
stop the motion and allow the support to function as designed). For example, when considering the instability of a support which requires the development of binding forces to ultimately naintain stability, one could assume the support does not act and then determine the resulting pipe deflection in the released direction.
If that deflection is a sufficient multiple (say 4) of the deflec-tion required to develop the necessary binding forces, it then becomes appropriate to further investigate the ability of the support to resist both the binding force and the applied load. During such an investigation, it is essential to demonstrate that the binding force mechanism possesses both sufficient strength and stiffness.
In other words, while certain designs may l
exhibit sufficient strength to develop and resist the necessary binding forces, they may not posssess sufficient stiffness to limit the rigid body displacement l
and thus resist the applied load. The alternative to this approach is to limit the consequences of the instability. This could be accomplished by showing that the piping and remaining supports are acceptable in the absence of the unstable support.
In either approach, before the design can be considered satisfactory, pipe stresses and other support reactions must be checked for the new displace-ments occurring at the support and the pipe must be checked for the effects of the binding forces.
Dynamic Versus Static Stability l
The preceeding discussion addresses only stability due f.o statically applied loading. The question arises as to whether a support could be unstable statically under the application of naximum load, yet stable when the same load is applied dynamically. This is a very complex analytic problem to resolve l
which is further complicated by the fact that the neximum loading on a pipe i
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summmmmmme ssewcas Mr. J. B. George February 19, 1985 Page 4 support is generally some combination of static and dynamic loads. Cygna is unaware of any established precedent for the acceptance of statically unstable supports based on dynamic arguments.
In some cases dynamic loading can contri-bute to pipe support instability rather than helping to preclude it. The time phasing of static and applied seismic (random) forces can either exacerbate or alleviate individual support instability. Therefore, to demonstrate analytically that a statically unstable support is dynamically stable would require an extensive evaluation using large nonlinear dynamic models and timo-history analyses. Add to this the variety of possible geometric configurations and input motions that must be considered, as well as the existence of static system preload (dead load plus thermal), and the problem becomes extremely costly to evaluate. This is a particularly unfavorable approach in view of the potentially inconclusive nature of the results.
For many of the same reasons stated above, any testing program developed to prove dynamic stability would also have to be very extensive. Tests which are severely displacement limited and sinusoidal (non-random) in nature can only prove that a support is stable under small amplitude displacement sinusoidal input. Such tests would not necessarily demonstrate stability under conditions which reflect the real nature of the random input motion.
System Stability Generally, the term system stability is associated with the arrangement of a structure's restraint configuration such that it is not possible for the struc-ture to undergo rigid body motion. We will refer to this as geometric stability. With respect to piping systems, geometric stability is assured when a pipe stress computer analysis is successfully executed. This computer analysis would have detected a system of supports which does not restrain each of the three translational and three rotational global degrees of freedom.
Encountering such a geometrically unstable system is an extremely rare situation 1
since almost all piping systems contain some type of anchor (e.g., equipment nozzle, penetration, structural anchor, etc.).
l When discussing system stability as it relates to pipe support stability, the major concern is the ability of the piping system to provide the appropriate stabilizing restraint for each support. This type of global stability can only be assured if each support is individually stable in its own right, either through its design (supports of the first category) or by adequate attachment to the pipe (supports of the second category).
If individual support stability is not assured, system stability is not guaranteed. The instability of one support can trigger the progressive instability of adjacent supports by causing the limits of the forces and displacements to which the adjacent supports were i
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originally designed to be exceeded. This may result in the formation of plastic F.
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u_amas Mr. J. B. George February 19, 1985 Page 5 hinges in the pipe (due to overload) which in turn nay develop into a collapse mechanism. This situation would not, however, prevent successful execution of a linear, elastic pipe stress computer analysis.
Demonstration of system stability by removal of an unstable support 3om the system and subsequently showing that each remaining support can resist the new forces is not sufficient by itself.
In addition, it should be shown that removing the unstable support does not affect the stability of other supports.
That is, overall system stability should be reevaluated in the absence of the removed support.
Commentary on TUGCO's Position Cygna has reviewed the Reference (3) Affidavit using the criteria described above. The Affidavit (pages 2-8) discusses system stability and its relation to individual support stability.
In it, TUGC0 states:
"In addition, if the total support scheme does not provide proper multidirection support required by the piping configuration, the analyst will be unable to successfully run the piping analysis computer program, (see Tr.12025 (Bjorkman testimony)).
In sumary, the piping analyst assures the stability of the piping system by limiting deflections, which negates any need to assess stability separately."
Cygna agrees with the first statement, since this is our basic definition of geometric stability. The second statement, however, does not follow. A piping analyst does not limit deflections to those required to assure system stability, since, in general, these deflections are not known. Rather, the analyst inputs each support as a restrained node and reports the resulting deformations to the designer for consideration. Therefore, the issue is not piping system stability, but rather the stability of the individual support itself. The key point is whether the individual support can resist the applied load within the initial eccentricities and displacement limits imposed upon it.
The stability issue is best illustrated in Figure 1(c) of the Affidavit, (page 4). The concern is not whether an adjacent support can provide a horizontal reaction component (since it is already known by analysis that it can and the system is geometrically stable), but rather whether the clamp (U-bolt) can provide sufficient resisting forces to prevent rotation of the clamp (U-bolt) about the pipe or slippage along the pipe axis.
If the clamp (U-bolt) cannot provide sufficient resisting torque, the individual support is unstable and system stability as well as progressive support instability must be re-evaluated.
senwcas Mr. J. B. George February 19, 1985 Page 6 Of the specific support configurations discussed in the Affidavit, the most unique is the box trame with zero-inch gap attached to a single strut or snubber (Affidavit, page 9). This is unusual because it relies solely on the relative thermal expansion between the pipe and frame during normal operation to create clamping forces. The resulting frictional forces which resist support rotation around the pipe and translation along the axis of the pipe would stabilize the support. The lower bound value of stabilizing frictional force which exists over the operational life of the plant was never determined either analytically or by test. Furthermore, since clamping forces do not exist at ambient condi-tions, it is possible for the support to move (rotate and translate) relative to the pipe. This movement of the support could be caused by normal vibration during start-up, operation or shut-down, combined with pipe thermal translation compatible within the rigid body displacement envelope of the support.
Subsequent to this movement the support may be in a position on the pipe which is outside of the displacement range for which it was designed and for which stability could be assured. Furthermore, due to the compatible rigid body motion of the pipe and support, the support would be unable to restrain the thermal movement (load) for which it was designed and adjacent supports would have to resist this load -- a load for which they were not designed. This situation may also develop at temperatures above ambient since the maintenance of zero gap over the life of the plant could be difficult to achieve. For these reasons, Cygna classifies these supports, without modification, as unstable.
In Figure 4 of the Affidavit (page 13) three methods are shown which have been utilized to modify the box frame supports to improve their stability. Two of these methods, " indexed lugs" and " additional struts" only provide rotational stability. They do not prevent translation of the support along the axis of the pipe with time. Therefore both of these modification schemes result in supports which must still be classified as unstable. The third modification scheme, the addition of cinched U-bolts, can prevent both rotation and translation of the support provided it can develop sufficient lower bound clamping forces. Since the final evaluation on the use of cinched U-bolts has not been completed, the acceptability of supports with this configuration remains an open issue at this time.
Cygna classifies all single struts with U-bolts and a thermal gap (Affidavit, page 15) as unstable since the stability of this type of support has never been analytically or experimentally demonstrated. Cygna understands that all of these supports have been modified in an effort to enhance stability (Affidavit, page 18). These modifications consist of either cinching the U-bolts or adding supplementary steel that would prevent the rotation of the U-bolt crosspiece.
Cygna believes we have addressed those supports for which supplementary steel was added to create " stability bumpers" in Reference (4) Observation PS-02.
Cygna found these bumpers unacceptable since there were no calculations to k.
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Mr. J. B. George February 19, 1985 Page 7 demonstrate that they possessed sufficient strength and stiffness to naintain stability. The stability of the supports which were modified by cinching the U-bolts remains open as part of the U-bolt analysis / testing program.
Double strutted frames (Affidavit, page 19) supporting two or more pipes were not encountered during any of the Cygna review phases. However, Cygna did find examples of double strutted frames supporting a single pipe and double strutted trapeze supports with U-bolts, which are configurations similar to those discussed in the Affidavit. As previously discussed for single strutted frames, both the double strutted frames and trapeze supports with uncinched U-bolts suffer from the problem of not having the demonstrated ability to maintain their relative position on the pipe over time. In addition, the double struts cannot be relied upon to resist compressive load until the frame (U-bolt) has rotated about an axis parallel to the struts and has bound itself in a cocked position against the pipe. Neither the stiffness requirements of the frame (U-bolt) necessary to naintain a stable position nor the binding forces and displacements required to restrict the unstability have been evaluated. Cygna therefore classifies these supports as unstable.
In the case of double strutted trapeze supports with cinched U-bolts, the most likely mode of instability is that due to rotation of the support about an axis parallel to the struts.
If the frictional resistance between the pipe and the trapeze crosspiece is not sufficient, the frictional bond will be broken and the entire destabilizing twisting moment must be resisted by the bending strength (and stiffness) of the U-bolt binding against the pipe. Since neither the frictional forces nor the U-bolt have been evaluated for their capability to resist this nonlinear destabilizing moment, Cygna classifies this configuration as unstable.
The stability of a single strut or snubber with a cinched U-bolt (Affidavit, page 27) is directly related to the resolution of the issue of U-bolts used as l
pipe clamps. Until the resolution of that issue, which includes the satisfac-tory determination that lower bound preloads can provide the clamping force necessary to resist the factored piping loads, Cygna considers all such supports to the unstable.
Classification of Cygna Review Scope Cygna has examined the 226 pipe supports wiGin the Phases 2, 3 and 4 review scope. Thirty-seven supports were identified as supports which, in the total absence of the pipe, are stable. Of the remaining 189 supports which in the-l absence of the pipe would be unstable,124 possess sufficient positive i
attachment to the pipe to ensure stability. The 65 potentially unstable supports may be classified as follows:
l l
semas Mr. J. B. George February 19, 1985 Page 8 Single strut with box frame or cinched U-bolt (23)
Double strut trapeze with cinched U-bolt (25)
Multi-strut box frame (8)
Single strut with uncinched U-bolt, stability bumpers (2)
Double strut, double trunnion with cinched U-bolt (1)
Double strut trapeze with box frame (2)
Double strut trapeze with uncinched U-bolt (3)
Triple strut box frame (1)
There are two reasons for classifying these supports as unstable:
- 1) the unconventional methods used to develop the restraining forces between the pipe and the support, and 2) the lack of any demonstration that the restraining forces developed by these supports are sufficient to naintain the support's stability. Supports which are designed with cinched U-bolts to provide the necessary positive connection to the pipe nay be reclassified as stable if the j
U-bolt testing / analysis program and the application of the results to the individual supports in question is found to be acceptable.
It should be noted, however, that this program does not address the stability of supports which do not use U-bolts, nor does it evaluate the twisting strength of U-bolts used in trapeze supports.
l Conclusions l
f Throughout this latter, Cygna has applied a very rigorous definition of' rigid I
body instability. Cygna recognizes from a practical standpoint that many of these potentially unstable designs nay actually perform their intended function. However, we also recognize that the inability to quantify the actual
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behavior which nay help stabilize the support in practice necessitates that i
stability be viewed under more idealized conditions. For that reason the individually unstable supports identified above, and any similar configurations throughout the plant, should be evaluated using one of the following approaches:
Modify to provide adequate restraint at the pipe / support connection Demonstrate system stability in the presence of the unstable supports Quantitatively show that the individual supports are stable l
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SCEVDCE S Mr. J. B. George February 19, 1985 Page 9 Please call to discuss any questions or clarification necessary since this is a complex subject.
Ver
- yours, vy}y tr g
N.H. Wi lams Project Manager NHW/ajb cc:
S. Treby.(U.S. NRC)
S. Burwell (U.S. NRC)
V. Noonan (U.S. NRC)
D. Wade (TUGCO)
J. van Amerongen (EBASC0/TUGCO)
R. Ballard (G8H)
J. Ellis (CASE)
D. Pigott (Orrick, Herrington & Sutcliff)
J. Finneran (TUGCO) e
_~. _
(,.,, % :,
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND-LICENSING BOARD In'the Matter of
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TEXAS UTILITIES ELECTRIC
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Docket Nos. 50-445-1 COMPANY, et al.
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and 50-446-1 (Comanche Peak Steam Electric
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. Station, Units 1 and 2)
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CERTIFICATE OF SERVICE By my-signature.below, I hereby certify that true and correct copies of Notification of New and Significant Information and CASE's Supplement to CASE's 10/15/84 Motions and Answer to Applicants' Motion for Summary Disposition Regarding Stability of Pipe Supports have beenisent to the names listed below this 25th day of February.,' QSj[,
'by: Express Mail where indicated by
- and First Class Mail elsewhere.
- Administrative Judge Peter B. Bloch
- Nicholas S. Reynolds, Esq.
U. S. Nuclear Regulatory Commission Bishop, Liberman, Cook, Purcell
- 4350 East / West Highway, 4th Floor.
& Reynolds Bethesda, Maryland 20814 1200 - 17th St., N. W.
Washington, D.C.
20036
- Judge Elizabeth B. Johnson Oak Ridge National Laboratory
- Geary S. Mizuno, Esq..
P. O. Box X, Building 3500 Office of Executive Legal Oak Ridge, Tennessee
'37830 Director U. S. Nuclear Regulatory
- -Dr. Kenneth A. McCollom,' Dean Commission Division of Engineering, Maryland National Bank. Bldg.
Architecture and Technology
- Room 10105 Oklahoma State University 7735 Old Georgetown Road Stillwater, Oklahoma 74074 Bethesda, Maryland 20814
- Dr. Walter H. Jordan Chairman, Atomic Safety and Licensing Board Panel 881 W. Outer Drive Oak Ridge, Tennessee 37830 U. S. Nuclear Regulatory Commission Washington, D. C.
20555 1
Chairman Renea Hicks, Esq.
Atomic Safety and Licensing Appeal Assistant Attorney General Board Panel Environmental Protection Division U. S. Nuclear. Regulatory Commission Supreme Court Building Eashington, D. C.
20555 Austin, Texas 73711 Mr. Robert Martin Anthony Z. Roissan, Esq.
Regional Administrator, Region IV Trial Lawyers for Public Justice U. S. Nuclear Regulatory Commission 2000 P Street, N. W., Suite 611 611 Ryan' Plaza Dr., Suite 1000 Washington, D. C.
20036 Arlington,_ Texas. 76011 Mr. Owen S. Merrill Staff En;ineer.
.Lanny A. Sinkin 3022 Porter St., N. W.,
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'Adviscry Connittee for Reactor Washingten, D. ~ C.
20008 Safeguards (MS E-1016)
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20555 Dr. David H. Bolt:
~ 2012 S.'-' Polk Dallas, Texas 75224 Michael D. Spence, President Texas-Utilities Generating Cospany Skyway Tower 400 North Olive St., L.E. 81
' Dallas, Texas 75201
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Docketing and Service Section (3 copies)
Office of the Secretary U. S.'.Kuclear Regulatory Cos=ission 20535
- Wayhington, D. C.
0O
>o J s.') Juanita Ellis, President ASE (Citizens Association for Sound Energy) 1426 S. Polk Dallas, Texas 75224 214/946-9446 s
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