ML061570364

Entergy'S Response to New England Coalition'S Request for Leave to File a New Contention, with Exhibits 1 - 6

ML061570364
Person / Time
Site:	Vermont Yankee
Issue date:	05/25/2006
From:	Travieso-Diaz M Entergy Nuclear Operations, Entergy Nuclear Vermont Yankee, Pillsbury, Winthrop, Shaw, Pittman, LLP
To:	Atomic Safety and Licensing Board Panel
Byrdsong A T
References
50-271-OLA, ASLBP 04-832-02-OLA, RAS 11716
Download: ML061570364 (187)

Text

1?,45 1171/,

May 25, 2006 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION DOCKETED USNRC Before the Atomic Safety and Licensing Board May 25, 2006 (4:49pm)

OFFICE OF SECRETARY In the Matter of )) RULEMAKINGS AND ADJUDICATIONS STAFF

) Docket No. 50-271 ENTERGY NUCLEAR VERMONT )

YANKEE, LLC and ENTERGY ) ASLBP No. 04-832-02-OLA NUCLEAR OPERATIONS, INC. ) (Operating License Amendment)

(Vermont Yankee Nuclear Power Station) )

)

ENTERGY'S RESPONSE TO NEW, ENGLAND COALITION'S REQUEST FOR LEAVE TO FILE A NEW CONTENTION Pursuant to 10 C.F.R. § 2.309(h)(1), Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc.' (collectively, "Entergy") hereby submit this Response in opposition to the New England Coalition's Request for Leave to File a New Contention, filed on April 20, 2006 ("April 20 Request").:: The April 20 Request is inexcusably late and the new contention it proposes (the "April 20 Contention") fails to meet the admissibility requirements of 10 C.F.R. § 2.309(f). Accordingly, the April 20 Request should be denied.

I. BACKGROUND The relevant background for the April 20 Request is largely set forth in Entergy's May 1, 2006 Response ("Entergy's May 1 Response") to the New England Coalition's ("NEC") Request Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc. are the licensees of the Vermont Yankee Nuclear Power Station ("VY").

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-Fernplate1jF YJ-0c-3 7

for Leave to File New Contentions, submitted on April 6, 2006 ("April 6 Request"). Briefly summarized, on September 10, 2003, Entergy filed an application ("EPU Application") to increase the maximum authorized power level from 1593 megawatts thermal ("MWt") to 1912 MWt (extended power uprate or "EPU"). NEC filed a petition to intervene and request for a hearing with respect to the EPU Application.2 On November 22, 2004, the Board admitted two of NEC's proposed contentions. LBP-04-28, 60 NRC 548 (2004). Hearings on NEC's two admitted contentions are scheduled for September and October 2006.3 The April 6 Request sought the admission of three new contentions into this proceeding.

Entergy and the NRC Staff opposed the April 6 Request. On April 20,2006, NEC filed a new request seeking the admission of the April 20 Contention. Finally, on May 25, 2006, the Board issued its Memorandum and Order (Ruling on the Admissibility of Three Additional Contentions), LBP-06-14, 63 NRC (2006), in which it ruled that all three contentions propounded in the April 6 Request are inadmissible.

H. ARGUMENT A. The April 20 Request is Untimely NEC's April 20 Request seeks to introduce a contention about the performance of the steam dryer at VY, which is also the subject of the third of the rejected new contentions raised in the April 6 Request. In fact, the claims in that contention ("NEC Contention 7" as designated by 2 New England Coalition's Request for Hearing, Demonstration of Standing, Discussion of Scope of Proceeding and Contentions (Aug. 30, 2004) ("Petition").

3 Revised Scheduling Order (Apr. 13, 2006) at 3-5.

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the Board in LBP-06-14, see slip op. at 23) subsume the allegations in the April 20 Contention.

NEC Contention 7 states:

ENVY Technical Specification Proposed Change No.263 w/

Supplements 1-42 does not comply with Drafts GDC- 40 and 42 insofar as they require that protection must be provided against the dynamic effects of a LOCA.

Specifically, and in contradiction to Supplement 42 (provided to New England Coalition 12 05/2005) and ENVY testimony before the NRC Advisory Committee on.Reactor Safeguards (11/15/2005, 11/16,2005, 11/29/2005, 11/30/2005, 12/07/2005,12/08/2005, 12/09/2005), and the Steam Dryer Monitoring Plan endorsed in the NRC Final Safety Evaluation Report at page 50, and NRC staff endorsement of Ascension Power Testing as described in NRC

• staff's response to public comments on the SER at page 325, and NRC Staff's acceptance of ENVY steam dryer inspection results as determinative of no further crack growth at SER page 337, New England Coalition asserts that:

a. The fatigue and the intergranular stress corrosion cracks, (IGSCC) which already exist on various Vermont Yankee'steam dryer surfaces will increase in number and grow in size because of the higher stresses on the dryer structure from flow induced vibrations under EPU conditions.

b. The increase energy content in the flow under EPU conditions will increase the intensity and duration of the dynamic loads that' act on the dryer causing it potentially to fragment and generate many loose parts.

c. The loose parts may migrate to the Core region or the Main Steam Isolation Valve ("MSIV"), potentially blocking fuel flow channels and /or preventing the MSIV from isolating the containment following a main steam line break. The ultimate

..danger to the public from dryer failure is a core-melt with an early containment by pass.

d. Because the ascension to power tests, as described in Supplement 42, are limited to steady state conditions they will not provide any data that could indicate that the dryer would not fail catastrophically following LOCA. .

April 6 Request at 6-7. The April 20 Contention reads:

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The failure of modeling, testing, and analysis, in support of extended power uprate (EPU), to detect or predict recent discovery of a 5 foot crack with multiple branches on the surface of the Quad Cities Unit 2 dryer indicates that the technical basis for ascension power testing at the Entergy Vermont Yankee Nuclear Power Station, largely based on the Quad Cities model and methodology, is flawed and cannot reliably predict steam dryer durability or performance under EPU conditions. Because a cracked or fractured steam dryer can result in an accident, prevent mitigation of an accident, or increase the consequences of an accident, with a major catastrophic effects on public health and safety, and because Vermont Yankee is proceeding in an unknown condition, the Atomic Safety and Licensing Board, (ASLB) must not permit Vermont Yankee to operate at the EPU conditions until such time as it can be definitively demonstrated that the ascension power testing program at Vermont Yankee has not been invalidated by the experience at Quad Cities.

April 20 Request at 2-3.

Both contentions allege that the analytical methods used by Entergy at VY to predict the flow induced loadings on the steam dryer under EPU operating conditions are flawed. This claim is set out in more detail in the asserted bases for both contentions. NEC Contention 7 alleges, among other things, that Entergy has not developed an "adequate or technically defensible" analysis showing that rapid steam'dryer crack propagation will not occur.

Declaration of Dr. Joram Hopenfeld Supporting New England Coalition's New Contentions (April 6, 2006) ("Hopenfeld April 6 Declaration") at 12-13, N 1Og. and 10h. NEC further claims that the computer models used to calculate flow induced loads on the dryer are unreliable, and "can not predict reliably high cycle fatigue due to fluctuating loads during normal operations and following DBAs because they were not benched marked against full scale tests or at least properly scaled tests." Id. at 13-14, ¶ 10i.

Similarly, in his Declaration in support of the April 20 Request, Dr. Hopenfeld asserts:

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The replacement dryer at Quad Cities Unit 2 was subjected to the state of the art Acoustic Circuit Model, (ACM) and stress analysis codes. The NRC was assured time and time again (ML060030127, ML051290326, ML060030125) that the analysis was conservative and that the steam line gauge measurements would preclude any possibility that the loads on the dryer would exceed their design limits.

The damage to the replacement dryer only after several months of operations demonstrates that the analytical tools and the monitoring instruments that are currently used to predict vibrations and dryer loads are not sufficiently accurate. This lack of accuracy can be expected if one considers the overall complexities which are inherent in the interaction of high velocity flows (168 fi/sec) with structures of complex geometries.

The analytical tools such as the ACM were derived from basic fluid dynamic equations that were tested on small-scale models.

Because of the presence of turbulence at these high flow rates, empirical parameters must be employed in the analysis, these parameters are known to be very sensitive to the geometry and size, and therefore unless the scaling laws are well understood, extrapolation of data from small test models to a large structure such as the dryer are subject to large uncertainties. From the history of crack formation at Quad Cities and other plants, it is apparent that the scaling laws of extrapolating data on dryer behavior from tests at the GE facility are not known.

The methodology of predicting the loads on the dryer at Vermont Yankee is essentially identical to the methodology that was used at Quad Cities (ML060930689, Vermont Yankee-Revision I to Steam Dryer Monitoring Plan).

Declaration of Dr. Joram Hopenfeld Supporting New England Coalition's Proposed New Contention (April, 17, 2006) ("Hopenfeld April 17 Declaration") at 3-4. Indeed, the April 20 Contention can be viewed as a particular example of the claims raised in NEC Contention 7 against the VY methodology for monitoring and predicting steam dryer flow induced loadings.

The only difference between the two contentions is evidentiary: In the April 20 Contention, 5

I NEC points to a recently discovered crack in the Quad Cities Unit 2 steam dryer (which NEC claims is due to flow induced vibration) as evidence that the Quad Cities methodology intended to predict and detect such cracks (which NEC claims is the same as is used at VY) is incapable of predicting their development.

Because the April 20 Contention is encompassed within the scope of NEC Contention 7 and the only difference between them is evidentiary, the April 20 Contention suffers from the same untimeliness deficiency that rendered NEC Contention 7 inadmissible. As discussed in Entergy's May 1 Response, Entergy developed a method, accepted by the NRC Staff, for ensuring that potential flow induced cracks on the steam dryer at VY during EPU operation are detected early in their formation. The method consists of monitoring of vibration during the recently completed power ascension program, coupled with technical analyses to show that the stress levels under EPU operation will not lead to fatigue induced cracks. In both contentions, NEC challenges the adequacy of the monitoring program and the analyses conducted by Entergy.

April 6 Request at 11-13; April 20 Request at 7-9.

The Board has ruled that NEC knew of Entergy's proposed steam dryer plan of action no later than November 2005, five months before the filing of the April 20 Contention. See LBP-06-14, slip op. at 25. Therefore, the claims against the steamdryer monitoring program and technical analyses raised in the April 20 Contention fail to satisfy the timeliness of submission requirement in 10 C.F.R. § 2.309(f)(2)(iii). 4 Id., slip op. at 13, 25-26. Also, for the reasons discussed in LBP-06-14, slip op. at 26, and in Entergy's May I Response at 19-22, the April 20 A proposed contention based on allegedly new information is admissible only if, inter alia, "[t]he amended or new contention has been submitted in a timely fashion based on the availability of the subsequent information."

10 C.F.R. § 2.309(f)(2)(iii).

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Contention fails to satisfy the eight-factor balancing test in 10 C.F.R. § 2.309(c)(1) for late-filed contentions. 5 Therefore, the contention is inadmissible.

NEC attempts to circumvent the untimeliness of the April 20 Contention by alleging that two new documents, released on April 1 and 12, 2006, provide the basis for the contention:

"[s]pecifically, NRC Staff's Technical Basis For Continued Power Ascension Of Vermont Yankee Nuclear Power Station Up To 110% Original Licensed Power (ML060970111) and, Vermont Yankee-Revision I to Steam Dryer Monitoring Plan (ML060930689)." April 20 Request at 3, 7. However, neither document supports that requirement. Revision 1 to the Steam Dryer Monitoring Plan (Exhibit I hereto) contains no new information that would be relevant to the April 20 Contention (or indeed to any new contention) and NEC cites none. Nor does the cited NRC "Technical Basis" document (Exhibit 2 hereto). That document refers to an evaluation performed by Entergy based on "a more conservative damping assumption in its assessment of the steam dryer skirt at Vermont Yankee than that used at Quad Cities. Even with this more conservative damping assumption, the stress in the skirt region of the Vermont Yankee steam dryer is calculated to be less than 1000 psi at 105% OLTP [original licensed thermal power]. Therefore, there is considerable margin in the stress analysis for the skirt region at Vermont Yankee to account for damping and other assumptions." See Exhibit 2 at 4. NEC, however, does not challenge the cited VY evaluation or point to it as the basis for its proposed With respect to factor (viii) in 10 C.F.R. § 2.309(c), the extent to which the petitioner's participation may be reasonably expected to assist in developing a sound record, NEC has shown itself unable to meet its fundamental obligation to timely file direct testimony on one of its two admitted contentions. See New England Coalition Statement of Position (May 17, 2006) at 6-8. This failure at least raises a question as whether NEC would be able to meet its obligations under 10 C.F.R. Part 2 on its April 20 Contention, were it to be admitted.

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new contention. Therefore, these documents provide no grounds for finding the April 20 Contention to be timely.

The March 2006 discovery of a five-foot long crack in the Quad Cities 2 steam dryer also provides no basis for rendering the April 20 Contention timely. As will be discussed below, the Quad Cities 2 crack has no relationship whatsoever with VY and provides no support for a new contention in this proceeding.

B. NEC's April 20 Contention does not Satisfy the Admissibility Requirements for Contentions in NRC Licensing Proceedings A proposed late-filed contention must satisfy the admissibility standards of 10 C.F.R. § 2.309(f)(1) (i)-(vi). LBP-05-32, 62 NRC 813, 822 (2005); Sacramento Municipal Utility District (Rancho Seco Nuclear Generating Station), CLI-93-12, 37 NRC 355, 362-363 (1993). This regulation requires a requestor to:

(i) Provide a specific statement of the issue of law or fact to be raised or controverted; (ii) Provide a brief explanation of the basis for the contention; (iii) Demonstrate that the issue raised in the contention is within the scope of the proceeding; (iv) Demonstrate that the issue raised in the contention is material to the findings the NRC must make to support the action that is involved in the proceeding; (v) Provide a concise statement of the alleged facts or expert opinions which support the requestor's/petitioner's position on the issue and on which the petitioner intends to rely at hearing, together with references to the specific sources and documents on which the requestor/petitioner intends to rely to support its position on the issue; and (vi) Provide sufficient information to show that a genuine dispute exists with the applicant/licensee on a material issue of law or fact.

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This information must include references to specific portions of the application (including the applicant's environmental report and safety report) that the petitioner disputes and the supporting reasons for each dispute, or, if the petitioner believes that the application fails to contain information on a relevant matter as required by law, the identification of each failure and the supporting reasons for the petitioner's belief.

10 C.F.R. § 2.309(f)(1)(i)-(vi). Failure to comply with any of the requirements may be grounds for dismissing a contention. Dominion Nuclear Connecticut, Inc. (Millstone Nuclear Power Station, Units 2 and 3), CLI-05-24, 62 NRC 551, 567 (2005), c Final Rule, "Changes to Adjudicatory Process," 69 Fed. Reg. 2,182, 2,221 (2004); Private Fuel Storage, LL.C.

(Independent Spent Fuel Storage Installation), CLI-99-10, 49 NRC 318, 325 (1999).

1. The April 20 Contention Lacks Factual Basis The entire basis for the April 20 Contention is NEC's allegation that "on April 7,2006, Quad Cities Unit 2 reported that an inspection of the Unit 2 steam dryer revealed a crack, approximately five feet in length with multiple branches in the skirt region of the dryer, plus additional lesser cracks on internal bracing. This dryer had been instrumented with several strain gauges, pressure transducers, and accelerometers, which failed to predict or detect the cracking."

April 20 Request at 2. NEC's witness Dr. Hopenfeld claims that "[b]ecause of the long history of crack formation and growth that were observed at Quad Cities in 2002, 2003 and 2004, it is, in my professional opinion, quite probable that flow induced vibration played a major part in causing the crack to reach a length of 5t." Hopenfeld April 17 Declaration at 4. Based on this conclusion, Dr. Hopenfeld opines that "[t]he damage to the replacement dryer only after several months of operations demonstrates that the analytical tools and the monitoring instruments that are currently used to predict vibrations and dryer loads are not sufficiently accurate." Id. at 3.

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Since, in Dr. Hopenfeld's view, "[t]he methodology of predicting the loads on the dryer at Vermont Yankee is essentially identical to the methodology that was used at Quad Cities," id. at 4, the experience at Quad Cities "clearly demonstrates that Entergy Nuclear Vermont Yankee cannot adequately assure NRC or the public that the plant can operate safely at the EPU conditions." Id.

Dr. Hopenfeld ostensibly bases his assessment of the causes of the Quad Cities 2 steam dryer crack on NRC Preliminary Notification of Event or Unusual Occurrence PNO-III-06-010 issued on April 7, 2006 (Exhibit 3 hereto). See Hopenfeld April 17 Declaration at 4. In that Preliminary Notification, the NRC advises of the discovery of the crack and states: "This crack is currently believed to have been caused by binding difficulties experienced during the initial installation last year, but the root cause evaluation is still in process." Exhibit 3 at 1. Nothing is said in that document to suggest that the crack is due to flow induced vibration forces exceeding values obtained from the model or instrumentation monitoring or challenging the "analytical 6

tools" and their "monitoring instruments".

Three days after the Preliminary Notification was issued, Exelon presented to the NRC the results of its inspection of the Quad Cities 2 steam dryer and reported its preliminary findings as to the cause of the crack. This document, "Quad Cities Unit 2 (QC2) Dryer Update" ("Dryer Update") (attached as Exhibit 4 hereto), is available in the ADAMS system with accession number ML061080570. In the Dryer Update, Exelon concluded that an impact on the dryer by 6 Dr. Hopenfeld points to the possibility that the five-foot Quad Cities 2 steam dryer crack was formed during the installation of the dryer "must also be considered". Hopenfeld April 17 Declaration at 4. He does not pursue this possibility, however, "since the on-line gauges are not capable of detecting the presence of cracks, the history of this crack is not knowable". Id.

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its support lugs while the dryer was being lifted caused plastic deformation of the skirt base ring and skirt plate of the dryer and this loading caused the formation of the crack. Exhibit 4 at 25.

The Dryer Update also concluded that, while flow induced vibration loads ("pressure oscillation loads") provided cyclic stress necessary to propagate the crack, "[p]ressure oscillation loading alone .. would not have initiated a fatigue crack." Id. at 30-31.

A formal root cause analysis performed by Exelon Nuclear of the causes of the Quad Cities Unit 2 steam dryer crack has been recently released. Exelon Nuclear Root Cause Report Q2R18 "Concerns Related to Steam Dryer" dated May 16, 2006 ("Root Cause Report"), Exhibit

.5hereto (available in the ADAMS system under accession number ML061420307). Its issuance lays to rest NEC's argument disputing "that there exists defensible technical basis [sic] for going forward with ascension power testing on the Quad Cities model until thorough root cause analysis of the Quad Cities Unit 2 failure has been completed and reviewed." April 20 Request at 10, 11. Now that the root cause analysis has been completed, NEC no longer has cause to dispute the technical basis for going forward with the EPU at VY "on the Quad Cities model".

The Root Cause Report confirms the preliminary assessment that the crack was not formed by flow induced vibrations during plant operations but was due to deformation caused by the dryer skirt base ring being caught on the reactor pressure vessel dryer support lugs while the dryer was being lifted in May 2005. Root Cause Report at 3. The report states: "Analyses completed by General Electric (GE) and reviewed by Exelon determined that without the additional stresses and material degradation resulting from the May 2005 lifting event, the operational loads were not sufficient to initiate cracking in the U-2 dryer skirt plate." Id. at 4.

Furthermore, "the Unit 1 steam dryer, which did not experience either the fabrication ovality or 11

installation lifting events, did not exhibit similar cracking when inspected in the Q1M19 outage in May 2006." Id. Again, the results of Exelon's investigation flatly contradict Dr. Hopenfeld's unsupported assertion.7 To provide a nexus between the Quad Cities 2 steam dryer crack and VY, Dr. Hopenfeld makes the unsupported conclusion that the undetected development of that crack "demonstrates that the analytical tools and the monitoring instruments that are currently used to predict vibrations and dryer loads are not sufficiently accurate.." Hopenfeld April 17 Declaration at 3.

There is nothing in the NRC Preliminary Notification, the Dryer Update, the final Root Cause Report or any other document to suggest that the analytical tools used to predict flow induced crack formation would (or should) have detected an impact caused crack, or that those tools proved in any way inadequate. 8 Dr. Hopenfeld provides neither support nor basis for drawing any connection between the "Quad Cities model" and the "Quad Cities Unit 2 failure". April 20 Request at 11.

Dr. Hopenfeld then leaps to the further unsupported conclusion that the methodology used at VY for monitoring and predicting the formation of steam dryer cracks must also be inadequate, since VY's methodology "is essentially identical to the methodology that was used at Quad Cities". Hopenfeld April 17 Declaration at 4. Dr. Hopenfeld cites Revision 1 to the VY Steam Dryer Monitoring Plan (Exhibit I hereto) as support of his claim that the methodology used to predict loads on the dryer at VY is "essentially identical" to that used at Quad Cities.

SWhile the Root Cause Report was issued after NEC's April 20 Request was filed, the report demonstrates that the filing of the request was at best premature and the April 20 Contention is lacking in basis.

Dr. Hopenfeld acknowledges that the monitoring tools (instrumentation) on the steam dryer are not intended to detect the presence of cracks. Hopenfeld April 17 Declaration at 4.

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This is not only without basis (there being nothing in Exhibit I to support it), but is also incorrect. While measured data from Quad Cities were used to calibrate the VY model, the methodology's application to VY is plant-specific. See Exhibit 6 hereto (excerpts from Attachment to Supplement 20 to EPU Application, BVY 04-113 (October 7, 2004), ADAMS Accession No. ML042890417).

In short, every premise in the strained syllogism constructed by Dr. Hopenfeld is erroneous. The "five foot crack" in the Quad Cities Unit 2 steam dryer was not caused by flow induced vibration; the analytical tools were not intended to predict a crack caused by physical impact; the failure of the analytical tools to predict the formation of that crack does not suggest inadequacy in the methodology used at Quad Cities; and the Quad Cities analytical model is not identical to the one used at VY, so no conclusions can be drawn on the application of that methodology from one plant to the other.

The April 20 Request is based on a series of erroneous assumptions and conclusions. The contention lacks factual basis and does not show "that a genuine dispute exists with the applicant/licensee on a material issue of law or fact" and thus fails to satisfy 10 C.F.R. § 2.309(f)(vi). It must be dismissed for, as the Board has noted, "[a]ny contention that fails directly to controvert the application or that mistakenly asserts the application does not address a relevant issue can be dismissed." LBP-04-28,160 NRC at 557.

2. The April 20 Contention is Impermissibly Vague and Speculative As discussed above, the April 20 Contention makes a number of factual assertions that are vague and unsupported. These include:

• The claim that "[i]nformation that is new and substantially different from that which preceded it [is contained in] NRC Staff's Technical Basis For Continued Power 13

Ascension Of Vermont Yankee Nuclear Power Station Up To 110% Original Licensed Power (ML060970111) and, Vermont Yankee-Revision 1 to Steam Dryer Monitoring Plan (ML060930689)." April 20 Request at 3. No such "new and substantially different" information is identified in the contention or in Dr.

Hopenfeld's April 17 Declaration. Nor is there any information (new or not) in those documents that relates in any way to the proposed contention.

• The claim that "both NRC Staff and Entergy Nuclear Vermont Yankee now take the position that the failure-of the Quad Cities 2 modeling and methodology to either predict or detect substantial cracking of the Quad Cities 2 steam dryer is irrelevant to continued use of the Quad Cities 2 modeling and methodology at Vermont Yankee."

April 20 Request at 7. NEC does not identify where such a position is stated by either Entergy or the NRC Staff. Nor is there any support for the claim that the Quad Cities 2 cracking should have been detected or predicted by the methodology used there to predict flow induced loadings on the steam dryer, or that the methodology was intended to detect or predict a fatigue crack initiated by physical impact.

• The assertion that "'themethodology of predicting the loads on the dryer at Vermont Yankee is essentially identical to the methodology that was used at Quad Cities." Id.

In reality, as discussed above, the modeling at VY is plant-specific.

In short, as was the case with NEC Contention 7, no supporting evidence is offered for the claims raised in the April 20 Contention; no nexus is shown between the Quad Cities 2 steam dryer's five-foot crack and VY; and there is no description of the deficiencies alleged to exist in the VY analyses and monitoring program.

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It is well settled that vague or conclusory assertions, even by an "expert" cannot support the admission of a proffered contention. Without more, such undefined assertions fail the Commission's tests for specificity and basis. 10 C.F.R.§ 2.309(f)(1)(i) and (ii); Baltimore Gas &

Electric Co. (Calvert Cliffs Nuclear Power Plant, Units I and 2), CLI-98-14, 48 NRC 39, 41 (1998); Fansteel, Inc. (Muskogee, Oklahoma Site), CLI-03-13, 58 NRC 195, 203 (2003);

Dominion Nuclear North Anna, LLC (Early Site Permit for North Anna ESP Site), LBP-04-1 8, 60 NRC 253, 265 (2004).

Failure to adequately support a contention's bases requires that the contention be rejected. Arizona Public Service Co. (Palo Verde Nuclear Generating Station, Units 1, 2 and 3),

CLI-91-12, 34 NRC 149, 155 (1991). The April 20 Contention lacks an adequate basis and should not be admitted.

III. CONCLUSION The April 20 Request constitutes yet another NEC attempt to introduce into this proceeding at the eleventh hour an issue that is untimely, lacking in factual basis, and impermissibly vague. Its unjustified untimeliness bars it from admission, as the Board has already ruled in LBP-06-14 with respect to the essentially identical NEC Contention 7. That Board ruling is the "law of the case" and dictates the rejection of the contention. See, M Ohio Edison Co. (Perry Nuclear Power Plant, Unit 1), LBP=92-32, 36 NRC 269, 283 (1992), aff'd on other grounds City of Cleveland v. NRC, 68 F.3d 1361 (D. C. Cir. 1995). In addition, NEC has 15

failed to meet the Commission's other admissibility standards, and for that reason also the April 20 Contention is inadmissible. Entergy respectfully requests that April 20 Request be denied.

Respectfully submitted, Jay E. Silberg Matias F. Travieso-Diaz Scott A. Vance PILLSBURY WINTHROP SHAW PITTMAN LLP 2300 N Street, N.W.

Washington, DC 20037-1128 Counsel for Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc.

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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Before the Atomic Safety and Licensing Board

)

In the Matter of )

) Docket No. 50-271 ENTERGY NUCLEAR VERMONT )

YANKEE, LLC and ENTERGY ) ASLBP No. 04-832-02-OLA NUCLEAR OPERATIONS, INC. ) (Operating License Amendment)

(Vermont Yankee Nuclear Power Station) )

)

CERTIFICATE OF SERVICE I hereby certify that copies of"Entergy's Response to New England Coalition's Request for Leave to File a New Contention" were served on the persons listed below by deposit in the U.S. mail, first class, postage prepaid, and where indicated by an asterisk by electronic mail, this 25th day of May, 2006.

• Administrative Judge *Administrative Judge Alex S. Karlin, Chair Lester S. Rubenstein Atomic Safety and Licensing Board Panel 4760 East Country Villa Drive Mail Stop T-3 F23 Tucson, AZ 85718 U.S. Nuclear Regulatory Commission lesrrr(,comcast.net Washington, D.C. 20555-0001 ask2anc.gov

• Administrative Judge Atomic Safety and Licensing Board Dr. Anthony J. Baratta Mail Stop T-3 F23 Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Mail Stop, T-3 F23 Washington, D.C. 20555-0001 U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 aib5(mnrc.gov

• Secretary Office of Commission Appellate Att'n: Rulemakings and Adjudications Staff Adjudication Mail Stop O-16 C1 Mail Stop O-16 Cl U.S. Nuclear Regulatory Commission U.S. Nucilar Regulatory Commission Washington, D.C. 20555-0001 Washington, D.C. 20555-0001 secvy rc.yov hearingdocket@'nrc. gov

• Raymond Shadis *Sherwin E. Turk, Esq.

New England Coalition *Steven C. Hamrick, Esq.

P.O. Box 98 Office of the General Counsel Shadis Road Mail Stop 0-15 D21 Edgecomb, ME 04556 U.S. Nuclear Regulatory Commission shadis(*prexar.com Washington, D.C. 20555-0001 set(fnrc.gov. schl (,nrc. gov

• Marcia Carpentier *Jonathan Rund Atomic Safety and Licensing Board Panel Atomic Safety and Licensing Board Panel Mail Stop T-3 F23 Mail Stop T-3 F23 U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Washington, D.C. 20555-0001 mxc7,nrc.gov imr3 Anrc. ov MaisF. Travieso-iaz 2

Entergy Nuclear Northeast Entergy Nudear Operations, Inc.

Vermont Yankee P.O. Box 050 185 Old Feny Road Brattleboro. VT 05302.0500 Tel 802 257 5271 March 26,2006 Docket No. 50-271 BVY 06-031 TAC No. M00761 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Vermont Yankee Nuclear Power Station Revision I to Steam Dryer Monitorina Plan

References:

1) Entergy letter to U.S. Nuclear Regulatory Commission, "Vermont Yankee Nuclear Power Station, License No. DPR-28 (Docket No. 50-271), Technical Specification Proposed Change No. 263, Extended Power Uprate," BVY 03-80, September 10, 2003

2) Entergy letter to U.S. Nuclear Regulatory Commission, "Vermont Yankee Nuclear Power Station, Extended Power Uprate - Regulatory Commitment Information Regarding Steam Dryer Monitoring and FIV Effects,"

BVY 06-019, February 26, 2006 This letter provides updated Information pursuant to a regulatory commitment made In connection with the application by Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc. (Entergy) for a license amendment (Reference 1, as supplemented) to Increase the maximum authorized power level of the Vermont Yankee Nuclear Power Station (VYNPS) from 1593 megawatts thermal (MWt) to 1912 MWt.

Attachment 1 Includes a revision (Revision 1) to the Steam Dryer Monitoring Plan (SDMP) that was previously provided In Reference 2. The SDMP will remain In effect until Ucense Condition 3.M expires. The SDMP, together with the EPU Power*Ascension Test Procedure (PATP) provides for monitoring, Inspecting, evaluating, and prompt action in response to potential adverse flow effects on the steam dryer as a result of power uprate operation. These actions provide assurance of the continued structural Integrity of the steam dryer under Extended Power Uprate conditions. Attachment 2 provides the justification, consistent with Ucense Condition

.3.M.4 for why this change does not require prior NRC approval.

Exhibit 1

BVY 06-031 Docket No. 50-271 Page 2 of 2 There are no new regulatory commitments contained In this submittal.

If you have any questions or require additional Information, please contact Mr. James DeVinoentis at (802) 258-4236.

Sincerely, Norman L Rademacher Director Nuclear Safety Assurance Vermont Yankee Nuclear Power Station Attachments (2) co: Mr. Samuel J. Collins (w/o attachments)

Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406-1415 Mr. Richard B. Ennis. Project Manager Project Directorate I Division of Ucensing Project Management Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mali Stop 08B1 Washington, DO 20555 USNRC Resident Inspector Entergy Nuclear Vermont Yankee, LLC P.O. Box 157 Vernon, Vermont 05354 Mr. David O'Brien, Cormmissloner VT Department of Public Service 112 State Street- Drawer 20 Montpelier, Vermont 05620-2601

BVY 06-031 Docket No. 50-271 Attachment 1 Vermont Yankee Nuclear Power Station Steam Dryer Monitoring Plan Revision 1 (exludrinof pages inArachmett 2 1 (excluding this cover sheet) Is20.

i Entergy Vermont Yankee Steam Dryer Monitoring Plan Revision 1 March 25, 2006 3Ao?.,r,;0Z7-t-Prepared B eraig J. Nichols Date Reviewed B QP~fm'es CalJhtan Date Approved Qohn breAuss Date u

Page I of 19 Rev. I VERMONT YANKEE NUCLEAR POWER STATION STEAM DRYER MONITORING PLAN Introduction and Purpose The Vermont Yankee Steam Dryer Monitoring Plan (SDMP) describes the course of action for monitoring and evaluating the performance of the Vermont Yankee Nuclear Power Station (VYNPS) steam dryer during power ascension testing and operation above 100% of the original licensed thermal power (OLTP), i.e., 1593 MWt, to the full 120% extended power uprate (EPU) condition of 1912 MWt to verify acceptable performance. The SDMP also addresses long-term actions necessary to implement proposed Ucense. Condition 3.M. Through operating limits, periodic surveillances, and required actions, the Impact of potentially adverse flow effects on the structural Integrity of the steam'dryer will be minimized.

The SDMP also provides information about the equipment and computer analysis methodologies used to monitor Steam Dryer performance.

Unacceptable steam dryer performance Is a condition that could challenge steam dryer structural integrity and result in the generation of loose parts, cracks or tears in the steam dryer that result in excessive moisture carryover. During reactor power operation, performance is demonstrated through the measurement of a combination of plant parameters.

Scope The SDMP is primarily an initial power ascension test plan designed to assess steam dryer performance from 100% OLTP (i.e., 1593 MWt) to 120% OLTP (i.e., 19112 MWt) and to perform confirmatory Inspections for a period of time following Initial and continued operation at uprated power levels. Power ascension to 120% OLTP will be achieved in a series of power step increases and holds at plateaus corresponding to 80 MWt increments above OLTP. Elements of

• this plan will be implemented before EPU power ascension testing, and others may continue after power ascension testing.

There are three main elements bf the SDMP:

1. Slow and deliberate.power ascension with defined hold points and durations, allowing S

time for monitoring and analysis;

2. A detailed power ascension monitoring and analysis program to trend steam dryer performance (primarily through the monitoring of steam dryer load signals and moisture carryover); and

3. A long term inspection program to verify steam dryer performance at EPU operating conditions.

Several elements of the SDMP also provide for completion of the necessary actions to satisfy the requirements of license conditions associated with the EPU license amendment. A comp!ete tabulation of the provisions of the license condition and the implementing strategy to complete them is containeld in Table 3.

Page 2 of 19 Rev. I Power Ascension VYNPS procedure ERSTI-04-VY1-1409-000, aPower Ascension Test Procedure for Extended Power Conditions 1593 to 1912 MWth," (PATP) will provide controls during power ascension testing- and confirm acceptable plant performance.. Other procedures may be entered to conduct specialized testing, such as condensate and feedwater testing. The VYNPS power ascension will occur over an extended period with gradual increases in power, hold periods, and engineering analyses of monitored data that must be approved by station management.

Relevant data and evaluations will be transmitted to the NRC staff in accordance with the provisions of the license condition. The PATP includes:

1. Power ascension rate of 16 MWI/hr;

2. Hourly monitoring of steam dryer performance during power ascension (required by License Condition 3.M);

3. Four hour holds at each 40 MWt; and

4. Minimum 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> holds at each 80 MWt power plateau to perform steam dryer-analysis allowing for NRC review, as appropriate (required by License Condition 3.M).

Monitorinq Plans Table 1 outlines the steam dryer surveillance requirements during reactor power ascension testing for EPU. The monitoring of moisture carryover and main steam line (MSL) pressure data provide measures for ensuring acceptable perflrmancd of the steam dryer. Frequent monitoring of these parameters will provide early detection capability of off-normal performance.

Proposed License Condition 3.M will require that steam dryer performance criteria are met and prompt action is taken if unacceptable performance is detected. Entergy has established two performance levels (Level 1 criteria and Level 2 criteria) as described In Table 2 for evaluating steam dryer performance during EPU power ascension testing. The Level 1 criteria correspond to the limits specified in the proposed license condition, while the Level 2 criteria are operating action levels that may indicate reductions in margin.

The comparison of measured plant data against defined criteria derived from the steam dryer analyses described below provide a means to assess continued steam dryer structural integrity under EPU conditions.

Main Steam Fluctuating Pressure Monitoring System.(4etalls~contained in VYC-3001)-.-

" Main Steam Une Strain Gages Entergy has installed strain gages at two locations on each of the four MSLs in the primary containment and a data acquisition system (DAS) designed to reduce uncertainties In the evaluation of steam dryer loads. These strain gages and the associated data acquisition system have been selected and configured to maximize sensitivity and reliability while reducing data uncertainty.

" Acoustic Circuit Model (ACM)

The CDI Acoustic Model has been improved based on results of the instrumented Steam Dryer at Exelon's Quad Cities Station. The revision has resulted in reduced uncertainty and a more conservative representation of the peak frequencies.

Page 3 of 19 Rev. 1 Finite Element Model (FEM)

In response to industry operating experience with steam dryer cover plate cracking, the ANSYS FEM has been updated to include more refined analysis of key dryer structural components such as the lower cover plate, the gussets, gusset shoes, and associated welds.

Acoustic Circuit Analysis (ACA) System Uncertainty Evaluation The VY Acoustic Circuit Model (ACM) has been updated. The revised ACM was developed to bound maximum pressure loads from three sets of test data from the instrumented QC2 dryer testing performed In 2005. This updated ACM uncertainty assessment is based on the enhanced VY strain gage and data acquisition system and the revised CDI Bounding Pressure model parameters. The Scale Model-Test (SMT) benchmark evaluation and previous 790 MWe QC2 benchmark assessment that provided the uncertainty bases for the prior ACM have been accordingly deleted from this calculation.

The overall system uncertainty is based on the combination of the uncertainties of each of the elements. The uncertainty in the ACM loads Is derived from the following sources:

o Uncertainty of the ACM to conservatively predict pressure response at the significant frequencies o Uncertainty introduced by differences In sensor locations between QC2 and VY o Uncertainty Introduced as a result of the ability of the ACM or Structural Model to match load and structural frequencies o Uncertainty resulting from strain gage and measure uncertainties.

These uncertainties will then be combined by the square root sum of the squares (SRSS) method to assess the ACM load uncertainty.

As calculated in VYC-3001 the overall system uncertainty is 38%. This value Is used In the determination of the reduction of the limit curve factor resulting in the final limit curve, shown as Figures 1 through 8 of the SDMP. The contribution of each of fte factors noted above Is as follows:

Maximum Uncertainty of the ACA Methodoloci ACM ability to conservatively match peak response at the highest frequencies: 32%

Difference In sensor locations from QC2 to VY 7%

Ability of ACM or Structural Model to match response frequencies: 15%

SG and DAS ability to measure pressure In Pipe 11%

Combined Uncertainty by Square Root Sum of the Squares 38%

-CFD Load Uncertainty (Remains unchanged from Revision 0 of VYC 3001)

The CFD predictions using the Large Eddy Simulation runs for VY are on average 118%

above the RMS values of in-plant data with-a-standard deviation of 82%. Thereforea .-.

conservative estimate of uncertainty Is 118% - 82% = +38%. This would support 0%

uncertainty for the CFD load. Conservatively, VY has maintained a 15% CFD load uncertainty In the Limit Curve Factor assessment.

The CFD analysis with the +/-10% change in load step had an impact on the limiting stress by 4%. Therefore the CFD frequency uncertainty Is determined to be 4%. The total CFD uncertainty; uncCFD- sqrt(15A2 + ,02) = 16%.

Page 4 of 19 Rev. I System Monitoring Requirements o During power ascension, steam dryer performance will be monitored hourly through the evaluation of pressure fluctuation data collected from strain gages installed on the MSLs.

o The strain gage data collected hourly during power ascension will be compared against the stress limit curve that Is provided as Figures 1 - 8 of the SDMP and Is based on Entergy Calculation VYC-3001. If any frequency peak from the MSL strain gage data exceeds the stress limit curve (Level 1), Entergy will reduce the reactor power to a level at which the stress limit curve Is not exceeded.

o Additionally, Entergy will monitor data collected from accelerometers mounted to the main steam piping inside the drywell to provide additional insights into the strain gage signals.

o During hold points at each 80 MWt power level above current licensed thermal power, the collected data, along with a comparison to the steam dryer limit curve, will be transmitted to the NRC staff.

o For any circumstance requiring a revision to the steam dryer limit curve, Entergy will resolve uncertainties In the steam dryer analysis and provide the results of that evaluation to the NRC staff prior to further increases in reactor power.

o Entergy will resolve uncertainties In the steam dryer analysis with the NRC staff within 90 days of Issuance of the EPU license amendment. If resolution Is not made within this time interval, reactor operation will not exceed 1593 MWt. These. planned actions are in compliance with proposed License Condition 3.M.

Moisture Carryover

• Moisture carryover trending provides an Indicator of steam dryer Integrity. At each 40 MWt step, moisture carryover data will be taken and compared to the predetermined acceptance criteria (Table 2).

• Level 1 criterion (0.35%) Is based on the maximum analyzed value.

• The data taken at each 80 MWt plateau will be evaluated and documented In the assessment sent to the NRC for information.

OtherMonitoring

• Plant data that may be Indicative of off-normal steam dryer performance will be monitored during power ascension (e.g., reactor water level, steam flow, feed flow, steam flow distribution between the Individual steam lines). Plant data can provide an early Indication of unacceptable steam dryer performance. The enhanced monitoring of selected plant parameters will be controlled by the PATP and other plant procedures.

NRC Notifications

• In accordance with proposed Ucense Condition 3 M., at discrete power levels, and if the steam dryer stress limit curve (i.e., Level 1 criterion) is exceededd,°Ehf6fr,**iirr-ilrovide notifications to the NRC staff consisting of data and evaluations performed during EPU power ascension testing above 1593 MWt. Detailed discussions regarding new plant data.

Inspections, and evaluations will be held with NRC staff upon request. The designated NRC point of contact for such Information Is the NRC Project Manager for the VYNPS EPU.

a The results of the SDMP will be submitted to the NRC staff In a report within 60 days following the completion of all EPU power ascension testing. In addition the final full EPU power performance criteria -spectra (i.e., steam dryer stress limit curve) will be submitted to the NRC staff within 90 days of license amendment issuance. Contemporary data and results from steam dryer monitoring will be available on-site for review by NRC Inspectors as it becomes available; The written report on steam dryer performance during EPU power

Page 5 of 19 Rev. I ascension testing will include evaluations or corrective actions that were required to obtain satisfactory steam dryer performance. The report will include relevant data collected at each power step, comparisons to performance criteria (design predictions), and evaluations performed in conjunction with steam dryer structural integrity monitoring.

Long Term Monitoring The long-term monitoring of plant parameters potentially indicative of steam dryer failure will be conducted, as recommended by General Electric Service Information Letter 644, Rev. 1 and consistent with Ucense Condition 3.M.

Moisture Canryover Per VYNPS station operating procedure OP-0631, mRadiochemistry," moisture carryover is periodically monitored for moisture carryover during normal plant operations. VYNPS off-normal procedure ON-3178, 'Increased Moisture Carryover," provides guidance to evaluate any elevated moisture carryover results Including that resulting from potential vessel Internals damage. This monitoring will also provide insight into changes In moisture carryover values during changing reactor core configurations (control rod pattems)

Strain Gage Monitoring As the strain gages will remain operational and can provide for future data collection, additional strain gage monitoring will be performed as determined appropriate during the remainder of the operating cycle following EPU Implementation.

Inspections The VYNPS steam dryer will be Inspected during the refueling outages scheduled for the Spring 2007, Fall 2008, and Spring 2010. The inspections conducted after power uprate implementation will be comparable in scope to the Inspection conducted during the Spring 2004 refueling outage and will be in accordance with the guidance in SIL 644, Rev. 1.

Reporting to NRC Steam Dryer Visual Inspections: The results of the visual Inspections of the steam dryer conducted during the next three refueling outages shall be reported to the NRC staff within 60 days following startup from the respective refueling outage.

Page 6 of 19 Rev. 1 Table 1 Steam Dryer Surveillance Requirements During Reactor Power Operation Above a Previously Attained Power Level Parameter Surveillance Frequency

1. Moisture Carryover Every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (Notes 1 and 2)

2. Main steam line pressure data Hourly when initiallyincreasing power above a from strain gages previously attained power level AND At least once at every 40 MWt (nominal) power step

._Mainsteamlinedatafro above 100% OLTP (Note 3)

3. Main steam line data from At least once at every 40 MWt (nominal) power step accelerometers above 100% OLTP (Note 3)

AND Within one hour after achieving every 40 MWIt

_(nominal) power step above 100% OLTP Notes to Table 1:

1. If a determination of moisture carryover cannot be made within.24-hours of achieving an 80 MWt power plateau, an orderly power reduction shall be made within the subsequent 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to a power level at which moisture carryover was previously determined to be acceptable. For testing purposes, a power ascension step Is defined as each power increment of 40 MWt, i.e., at thermal power levels of approximately 102.5%, 105%, 107.5%,

110%, 112.5%, 115%, 117.5%, and 120% OLTP. Power level plateaus are nominally every 80 MWt.

2. Provided that the Level 2 performance criteria in Table 2 are not exceeded, when steady state operation at a given power exceeds 168 consecutive hours, moisture carryover monitoring frequency may be reduced to once per week.

3. The strain gage surveillance shall be performed hourly when Increasing power above a level at which data was previously obtained. The surveillance of both the strain gage data and MSL pressure data is also required to be performed once at each 40 MWt power step above 1593 MWt and within one hour of achieving each 40 MWZ step in power, I.e., af thermal power levels of approximately 102.5%, 105%, 107.5%, 110%, 112.5%, 115%, 117.5%, and 120% OLTP (i.e., 1593 MWt). If the surveillance is met at a given power level, additional surveillances do not need to be performed at a power level where data had previously been*

obtained.

If valid strain gage data cannot be recorded hourly or within one hour of initially reaching a 40 MWt power step from at least three of the four MSLs, an orderly power reduction shall be made to a lower power level at which data had previously been obtained. Any such power level reduction shall be completed within two hours of determining that valid data was not recorded.

Page 7 of 19 1

Rev.

Table 2 Steam Dryer Performance Criteria and Required Actions Performance Criteria Not to be Required Actions if Performance Criteria Exceeded and Required Exceeded Completion Times Level 2: 1. Promptly suspend reactor power ascension until an engineering

• Moisture carryover exceeds evaluation concludes that further power ascension is justified.

0.1% 2. Before resuming reactor power ascension, the steam dryer OR performance data shall be reviewed as part of an engineering evaluation to assess whether further power ascension can be made

• Moisture carryover exceeds without exceeding the Level 1 criteria.

0.1% and increases by

> 50% over the average of the three previous measurements taken at

> 1593 MWt OR

• Pressure data exceed Level 2 Spectra1 Level 1: 1. Promptly initiate a reactor power reduction and achieve a previously acceptable power level (i.e., reduce power to a previous step level)

• Moisture carryover exceeds within two hours, unless an engineering evaluation concludes that 0.35% continued power operation or power ascension is acceptable.

OR

2. Within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, re-measure moisture carryover and perform an

• Pressure data exceed Level engineering evaluation of steam dryer structural integrity. Ifthe I Spectral results of the evaluation of steam dryer structural integrity do not support continued plant operation, the reactor shall be placed In a hot shutdown condition within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. If the results of the engineering evaluation support continued power operation, implement steps 3 and 4 below.

3. Ifthe results of the engineering evaluation support continued power operation, reduce further power ascension step and plateau levels to nominal increases of 20 MWt and 40 MWt. respectively, for any additional power ascension.

4. Within 30 days, the transient pressure data shall be used to calculate the steam dryer fatigue usage to demonstrate that continued power operation Is acceptable.

' The EPU spectra shall be determined and documented in an engineering calculation or report.

Acceptable Level 2 spectra shall be based on maintaining < 80% of the ASME allowable alternating stress (Sj)value at 1011 cycles (i.e., 10.88 ksi). Acceptable Level 1 Spectra shall be based on maintaining the ASME S, at 10, cycles (i.e.. 13.6 ksi).

Page 8 of 19 Rev.. I Table 3 Steam Dryer License Conditions Ucense Condition Requirement Implementing Actions 3.M.1.ea Entergy shall monitor hourly the 32 During initial power ascension above 1593 MWt, main steam line (MSL) strain gages data from at least 32 strain gages will be collected during power ascension above 1593 and evaluated by Entergy's power ascension test MWt for increasing pressure team to verify that acoustic signals Indicative of fluctuations in the steam lines. increasing pressure fluctuations In the steam lines are not challenging the steam dryer stress-limit curve. Monitoring will be conducted hourly during any power *ascension above a previously attained power level.

(Reference ERSTI-04-VY1-1409-000),

(Reference PCRS tracking item WT-VTY-2005-00000-01803) 3.M.1l.b Entergy shall hold the facility for 24 The PATP has established test plateau Increments hours at 105%, 110%, and 115% of of approximately 80 MWt (corresponding to 105%,

OLTP (i.e., 1593 MWt) to collect 110%, and 115% of 1593 MWt). Reactor power will data from the 32 MSL strain gages not be increased above the plateau for a minimum required by License Condition of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />. During the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of steady 3.M.l.a, conduct plant Inspections state operation at each plateau, strain gage data and walkdowns, and evaluate steam will be collected from all available strain gages dryer performance based on these (minimum of 32) and evaluated to demonstrate data; shall provide the evaluation to acceptable steam dryer performance. Additionally, the NRC staff by facsimile or moisture carryover measurements will be made at electronic transmission to the NRC each plateau and every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during power project manager upon completion of ascension testing. At the 80 MWt plateau hold the evaluation; and shall not points, Entergy will conduct plant walkdowns and Increase power above each hold inspections of plant equipment, Including piping and point until 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> after the NRC components identified as potentially vulnerable to project manager confirms receipt of flow-induced vibration (FlV) In accordance with the the transmission. PATP and other plant procedures. Steam dryer performance will be evaluated based on these data.

The 24-hour period and the 96-hour period may overlap once the transmittal Is provided to the NRC staff.

The evaluations of steam dryer performance, based on the data collected during each of the 80 MWt plateaus, as well as the results of walkdowns and other measurements of FIV for various piping and plant components, will be provided to the NRC staff.

Arrangements haveý been made for electronic transmission through email and/or uploading to a designated website. Upon the NRC Project Manager confirming receipt of the steam dryer data and performance evaluation, the 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> of hold

Page 9 of 19 Rev. 1 License Condition Requirement Implementing Actions time will commence. Power will not be Increased above each of the 80 MWt hold points until the expiration of the 96-hour hold.

If during the hold periods, or at any other time, the NRC staff requests a discussion or requires clarification of the engineering evaluations provided in fulfillment of this requirement, Entergy. will promptly arrange for such discussions... Entergy will maintain a power ascension control center, Including management oversight, available 24/7 on-site during power Increases to previously unattalned power levels.

(Reference ERSTI-04-VY,-1409-000)

(Reference PCRS tracking item WT-VTY-2005-00000-01803) 3.M.l.c If any frequency peak from the MSL The steam dryer stress limit curve, provided strain gage data exceeds the limit herewith contains Level 1 and Level 2 criteria. If curve established by Entergy frequency peaks from MSL strain gage data exceed Nuclear Operations, Inc. and either Level 1 or Level 2 criteria, prompt action will submitted to the NRC staff prior to be taken in response to the potential adverse flow operation above OLTP, Entergy effects that might result Similar actions will occur if Nuclear Operations, Inc. shall return moisture carryover Is excessive and previously the facility to a power level at which established Level 1 or Level 2 criteria are the limit curve Is not exceeded. exceeded. The Level 2 criteria represent a Entergy Nuclear Operations, Inc. conservative action level for evaluation and close shall resolve the uncertainties In the monitoring of steam dryer performance-not a limit.

steam dryer analysis, document the The Level 1 criteria represent analytical limits and continued structural integrity of the additional actions may be warranted.

steam dryer, and provide that documentation to the NRC staff by If any frequency peak from the MSL strain gage facsimile or electronic transmission data exceeds the Level 1 steam dryer stress limit to the NRC project manager prior to curve, Entergy will reduce reactor power to a power further increases in reactor power. level at which the limit curve is not exceeded.

(Reference ERSTI-04-VY1-1409-000)

Prior to any-further-Increase-in-power above the reduced power level, Entergy will (1) resolve the uncertainties in the steam dryer analysis, (2) evaluate and document the adequate structural Integrity of the steam dryer, and (3) provide that documentation to the NRC staff. Any revision to the limit curve based on this evaluation will be provided to the NRC staff.

(Reference PCRS tracking Item WT-VTY-2005-00000-01803)

Page 10 of 19 Rev- 1 License Condition Requirement Implementing Actions 3.M.1.d In addition to evaluating the MSL Accelerometers mounted on MSL piping will be strain gage data, Entergy Nuclear monitored on an hourly basis during power Operations, Inc. shall monitor ascension testing to identify if resonances are reactor pressure vessel water level Increasing above nominal levels in proportion to instrumentation or MSL piping MSL strain gage data. If abnormally Increasing accelerometers on an hourly basis resonant- frequencies are detected, power.

during power ascension above ascension will be halted. Prior to .any further OLTP. Ifresonance frequencies are increase In -power, Entergy will (1) evaluate, and identified as increasing above document the adequate structural.. integrity.,of the nominal levels Inproportion to strain steam dryer, and (2) provide that documentation to gage instrumentation data, Entergy the NRC staff.

Nuclear Operations, Inc. shall stop (Reference ERSTI-04-VY1-1409-000) power ascension, document the (Reference PCRS tracking Item WT-VTY-2005-continued structural Integrity of the 00000-01803) steam dryer, and provide that documentation to the NRC staff by facsimile or electronic transmission to the NRC project manager prior to further Increases Inreactor power.

3.M.1.e Following start-up testing, Entergy After collecting strain gage data at approximately Nuclear Operations, Inc. shall the EPU full power level, Entergy will resolve the resolve the uncertainties in the uncertainties In the steam dryer analysis and steam dryer analysis and provide provide documentation of the resolution to die NRC that resolution to the NRC staff by staff. Ifthese actions cannot be achieved within 90 facsimile or electronic transmission days of Issuance of the license amendment, reactor to the NRC project manager. Ifthe power will be limited to 1593 MWL This uncertainty uncertainties are not resolved within evaluation may be prepared and provided to the

'90 days of issuance of the license NRC prior to reaching EPU full power levels amendment authorizing operation at associated with any proposed revision to the steam 1912 MWt, Entergy Nuclear dryer limit curve.

Operations, Inc. shall return the (Reference PCRS tracking item WT-VTY-2005-facility to OLTP. 00000-01803)

I*.M;Z nor: :toO:.peration *aboe :Q.LTp*' OM.PL:ETE,.-. "To' :e~nhancei: performnce: and

.trgy. iodear JOpratrionInc,. r the a ay.cc.. o the"steam' dryet

.hal..install..'32I ddional o a. urenent system,.Entergy has installed '48 on te

.age a - trlii.'agos a o.'.MS. pipang.d 'w..wll' ;a'nain

• hin.s-earnpipipg hail. enhance the:daa 'acUisItior nImum,of,32 operabe sdrain gages:during po~er in- order.:. o reuce.' tho

.sem sce n testi .. The9data dacuIsition,"syste easure mnt .. uncertant DAS).a:.g ed t..eU heu ssociated wi*JpJ*e ac*USti--thc

-'o ssociated.with the ACM6 p~~jA~¶ . 9, fleer ncid b.M.2.b n the .eveft,..that- kcustic 'ignals I .MPLETE - As partI.of the evaluation e. rformed

.. Wre de Ifidthit'ihallenge the limit *t'.173MW, Entergy. Vermont.Yankee.emp'oyed-a urve *during" power. :-scensior le, revision .of 1the 'Acoustic' Circuit.Model. In

Page 11 of 19

.Rev. 1 License Condition Requirement Implementing Actions bove.. OLTP, -. Entergyi.6 'NJe164 soclation-with the benchmarking of the new ACM

• p~ertiors .Incl*,.: shall"eaf. 'freqcUency,' spf ic, .ss0ssment of., the ACM team dryer -loads.nd rb"eatri *I .colanty wais perforned add ,[jcr*p!.in n --

curve b*ad

-elimit. a - th .,n, i .u.*tion vW C -001,Rev. 4.

frequencyseii asP6n .. ~0G1

..~ ~ n~

CM ..unce*rainty. ,-jh0_,-

_______ Jnai tioequency,:

3.M.2.c After reaching 120% of OLTP, After collecting strain. gage data .at.approxlmately Entergy Nuclear Operations, Inc. the EPU full power level, Entergy will establish the shall obtain measurements from the steam dryer flow-induced vibration load fatigue MSL strain gages and establish the margin for the facility, update the steam dryer stress steam dryer flow-induced vibration report, and re-establish the stress limit curve with load fatigue margin for the facility, the updated ACM load definition and revised update the steam dryer stress instrument uncertainty. This information will be report, and re-establish the steam included In the report to the NRC staff being made dryer monitoring plan (SDMP) limit in accordance with Ucense Condition 3.M.l.e.

curve with the updated ACM load (Reference. PCRS tracking item WT-VTY-2006-definition and revised Instrument 00000-00249) uncertainty, which will be provided to the NRC staff.

3.M.2.d scnt s VMLT ato the-1W pvlton bjrioned requfredn In0Vdh6 ih' r.:

rentrWN4ul.a rfiWh. V. SteamnDryeri:

Sivdsiorstthe model used In the

. -sha.llPner

.phe pe.atiorsJ

.'. ur riite:.FE.M hh0 he. Eemnent -Modt

-out ut ..w (FEM). .Aditionalanysse. io rfo me .to .assess .

halysls . o : ,i . fr. set IreqWuen y .i cen antles -:.- ,-The ."results -fthi*

rtalties.' up o.  %...*I.-...s e nment are.d-cnta lnd In C-ai .uldation. WVYi_

s~u

=lmsteda ta Pe '"4akesonses"- .1a ". 1a 01Rev.

Dhafat ~ I IV_____

3.M.2.e Entergy Nuclear Operations, Inc. The revised SDMP provides long-term monitoring of shall revise the SDMP to reflect steam dryer performance in accordance with GE long-term monitoring of plant SIL 644 Rev. 1.

parameters potentially indicative of (Reference PCRS tracking Item WT-VTY-2006-steam dryer failure; to reflect 00000-00250) consistency of the facility's steam -- --...

dryer inspection program with A.LET -he D1Tiiia.hePAl en1.f'I..*

General Bectric Services tRC SProject Manager.for the.VYNPSEPUasthe Information Letter 644, Revision 1; .oint.ofcon tact for _pt:ydipg

..SDMP..f.*f.04atjo and to identify the NRC .Project lodng power as'nsi6n .

Manager for the facility as the point f of contact for providing SDMP Information during power ascension. P5MN.PF -iE'.'. tur..carover, pro ures PP0631 and ..ON-3178t.,p.ro.v[de v fQr.-llb-te0rn riopitorin and cointrol.

Page 12 of 19 Rev..1 License Condition Requirement Implementing Actions 3.M.2.f Entergy Nuclear Operations, Inc. The final EPU steam dryer load definition will be shall submit the final extended included in the report provided to the NRC staff in power uprate (EPU) steam dryer accordance with License Conditions 3.M.l.e. and load definition for the facility to the 3.M.2.c.

NRC upon completion of the power (Reference PCRS tracking item WT-VTY-2006-ascension test program. 00000-00251)

FoytergNucle4.` Operatit6 s,.*lnJ. OMPLET'E,*-;Entergy'letterBVY .06-019 forwards hall.*- eubrnitte. A- i oflmw-fiu.- IV-related ,portios

of.the .

ERUJ;elOwQ

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,'aluatingspiei t,-*f'eo r.rpoW~r a.censi.on:t pry*,a .-'herewith. Th*

luat.fn-. .m**.r rti-..curve' W.d. .Vceoed. onthe .basisof F, Ol .- *h. . p * ,

• efencn the. PATP.

M.3(b) .F~ntergy p.repare.* fshall the. EPU I)MPLETE1 Sve l .ccomP.tins...

Wtartup. test procedure to lneUdo 0c .Odlfir.enthe PATP.

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~ rdthi 6 [fN~eferqnceo 7R~jp4-i T 900 tiration Arn. .LJ-;pwe

~sce~sJn NOM.()ntergy shall prepare thd.' EPUI OMPLT- Activities tobeaomisddrn

~taruprocdureto est nblujd "Iodpolnts~are specgifid in the F.ATP.'

• ctMties to-be accompIlshqd-Autr-ng .Rferdence -RS.T-04.-.V)1-14.ooo.)

Oldpoints_

Page 13 of 19 Rev.-_

License Condition Requirement Implementing Actions

• §I.3Ld) -'*tergy*" hall P..repare .. th0e,-EPU .. M.E'LE.- Pant parameters tQbe.n~qqie ta.t~up .:t .pr~oedure...in..du pecified inAttachment.9 to-th P.ATpL MtQ jtjtOtqrjQIbAg n I3t, _OYL:_J JQpaQQ9)

.;Me) =.-ntergy'. al j:.ePar .te..PUA .oMPLET. - otions! .and walkd.w .-to.-be M.nsp itart~up, :test .pr*deu t .. ~i3.. j.ndu~ct..ed.: for*.tear*rrfeeda.ter .:and condensate IsctnsanWakQ.n.t-b yteniis. itld -6 pohents:.ctg.in hbpjlt.0 Ionducted

• for -:steam, (iwat~f~rid~l:~ I~dln-.Att~ e~... nt .totthe PAT .

onid.Wensate. jlsen E!S.Q~y-49-p 04t YFepec

' t3(fI *tergy. shall-prepar -h:E .PLq ;OMP LETE -MMethod ' .Us-d todtrend plant

-tb**tb&

iaqup.tA. ts prozedur':.. cl*-

,to e ,a ers.ýre.ee !ijLA tta.pn..nt to t-te..g. shall,. p~r~epare..: *.-. .EJq 1.QM.PJETE..-.Acceptnc bcriteriaý for .monitoring tartuptest pfbcedu-'.tQ .n1- 4udd rid.,t.ng-plant. npw etey . _A'ndd*'coltlng thd

• cce.'pt~n~e:: crterao. -r..-.ft~fn* *...lldow..s aIb and"Inspec..o.s,-are .'specified I .!tre6dipg- Plant para.dietd.jrs"ia."nd Q.achmentE9 :tgti"_PMTP.;ee .R.T .

,M,,i.. Entergy..shail )arep.are.

tP- PLE:E E.:. -Adctionst. takenn"f- acceptane

• tartup t*dtaproceduri t..inu i.tenra are not satisiedlare'spe*.it*d InAT.P tcu;?46.t bd' lakerl Jl .1I R~nER4:iALyyi 9A-QC 4 ergy.: sal 1 prepre' 1nt tie,=..MPLETEr - Verification: of. I*e compeetion..-O trup. .et- roccuren nP~letion ificion=. 0f.te':'" to. ncu~do!.o 6 rnitrrin at*pnne cens..e-am~endmenht ction sp~ed In th

a~pplicatioraniddall supplements:l romiten4 and "pI1e.act:Q*0.0 a:" Jh. .appli6tion lP por.Pt,.of.tSt :EPU lcense qfief ldd 'In the lleins-e' ameandin601 O~ndn ipblicatio.n -and all 'suP[i..-ts.id 1 inAin Peifled r e'strbaf thi PeATP .

3gt th ta 1yrI he"appicatn n. s.up.ro.F",th f U :licnse fla.ni~ amendment o jh**-:e,..rjy"

Page 14 of 19 Rev. 1 3.M.4 When operating above OLTP, the These restrictions are provided in the PATP and/or operating limits, required actions, the SDMP.

and surveillances specified in the (Reference ERSTI-04-VY1-1409-000)

SDMP shall be met. The following key attributes of the SDMP shall not be made less restrictive without prior NRC approval:

a. During initial power ascension testing above OLTP, each test plateau Increment shall be approximately 80 MWt;

b. Level I performance criteria; and

c. The methodology for establishing the stress spectra used for the Level 1 and Level 2 performance criteria.

Changes to other aspects of the SDMP may be made in accordance with the guidance of NEI 99-04.

.3.M.5. During each of the three scheduled The VYNPS steam dryer will be. inspected during refueling outages (beginning with the refueling outages scheduled for the Spring the spring 2007 refueling outage), 2007, Fall 2008, and Spring 2010. The Inspections a visual Inspection shall be conducted after power uprate implementation will conducted of all accessible, be comparable to the Inspections conducted during susceptible locations of the steam the Spring 2004 and Fall 2005 refueling outages dryer, Including flaws left 'as Is' and will be In accordance with the guidance in SIL and modifications. 644, Rev. 1.

(Reference PCRS tracking item WT-VTY-2006-00000-00253)

(Reference PCRS tracking. item WT-VTY-2006-00000-00254):

(Reference* PCRS tracking item WT-VTY-2006-

& I 00000-00255)

7 Page 15 of 19 Rev. I 3.M.6 The results of the visual The VYNPS steam dryer will be inspected during Inspections of the steam dryer the refueling outages scheduled for the Spring conducted during the three 2007, Fall 2008, and Spring 2010. The Inspections scheduled refueling outages conducted after power uprate implementation will (beginning with the spring 2007 be comparable to the inspections conducted during refueling outage) shall be, reported the Spring 2004 and Fall 2005 refueling outages to the NRC staff within 60 days and will be in accordance with the guidance in SIL following startup from the

• 644, Rev. 1. The results will be documented in a respective refueling outage. The report and submitted to the NRC within 60 days results of the SDMP shall be following completion of all EPU power ascension submitted to the NRC staff In a testing.

report within 60 days following the (Reference PCRS tracking Item WT-VTY-2006-completion of all EPU power 00000-00256) ascension testing. (Reference PCRS tracking item WT-VTY-2006-00000-00257)

(Reference PCRS tracking item WT-VTY-2006-

00000-00258) 3.M.7 The requirements of paragraph When operating above 1593 MWt, the operating 3.M.4 above for meeting the SDMP limits, required actions, and surveillances specified shall be Implemented upon In the SDMP will be. met. Those key attributes of Issuance of the EPU license the SDMP specified .in Ucense Condition 3.M.4 will amendment and shall continue. not be made less restrictive without prior NRC until the completion of one full approval.

operating cycle at EPU. If an (Reference PCRS tracking Item WT-VTY-2006-unacceptable structural flaw (due. 00000-00259) to fatigue) Is detected during the subsequent visual Inspection of the steam dryer, the requirements of paragraph 4 shall extend another full operating cycle until the visual Inspection standard of no new flaws/flaw growth based on visual Inspection is satisfied.

3.M.8 This license condition Shall.expire (Reference PCRS tracking item WT-VTY-2006-upon satisfaction of the 00000-00260) requirements In paragraphs 5, 6, and 7 provided that a visual Inspection of the steam dryer does not reveal any new unacceptable flaw or unacceptable flaw growth that is due to fatigue. _

Page 16 of 19 Rev. I MSL A Upper 1hE404 v .A ' tW 1 L.

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-L I. A8.,* AveJ~AL wer "'LC-I An-ML-LomerJ Fiqure 2: Steam Dryer Stress Litmit Curve - MSL WA Lower

Page 17 of 19 Rev.

1 MSL B Upper

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Page 18 Of 19 Rev. 1 ..

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Page 19 of 19 Rev. 1 MSL D Upper

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BVY 06-031 Docket No. 50-271 Attachment 2 Vermont Yankee Nuclear Power Station Steam Dryer Monitoring Plan Basis for Compliance with License Condition 3.M.4 I(excWdng tiIs cor sheet) is3). I

4.

Page I of 3 Bases for Compliance with License Condition 3.M.4

Reference:

ERSTI-04-VYI-1409-000, "Power Ascension Test Procedure for Extended Power Conditions 1593 to 1912 MWM (PATP)

Purpose:

This document assesses compliance of changes to the Vermont Yankee steam dryer monitoring models with Vermont Yankee Ucense Condition 3.M.4. In addition, an assessment of the ability of the-steam dryer to support operation at the next power plateau is also Included herein.

Discussion:

On March 4, 2006 Vermont Yankee Nuclear Power Stations (VYNPS) raised reactor power from 1593 MWt to approximately 1673 MWt, the first power ascension plateau. At that power level the lower set of strain gages on the 'A' main steam line provided an Indication at 137 Hz that exceeded the Level 2 Acceptance Criteria of the Steam Dryer Monitoring Plan (SDMP). Entergy Vermont Yankee entered the corrective action program and performed an engineering evaluation which concluded that continuous operation at the first power plateau (1673 MWt) would not. challenge steam dryer Integrity.

Entergy Verinont Yankee uses an Acoustic Circuit Model (ACM) and an ANSYS Finite Bement Model (FEM) to monitor performance of the steam dryer. To address the aforementioned 137 Hz peak, these models have been updated In accordanOe with requirements established In License Condition 3.M of the Vermont Yankee Extended Power Uprate Ucense Amendment. Details of these changes are discussed later in this document:

The-scope of the analyses performed and the results are included In Entergy Vermont Yankee calculation VYC-3001, Revision 1. This calculation includes In part:

• Strain Gage Data from 1593 MWt and 1673 MWt

• Acoustic Circuit Model Benchmark Report a ACM Uncertainty Evaluation

• Stress Analysis Model Description

• Stress Analysis Results a Limit Curve Development

• Revised Umit Curves Based on the Improvements in the monitoring system and analysis techniques and evaluation of the VYNPS specific signals at 1673 MWt, an engineering evaluation has been'cormpleted and has concluded that the strain gage signals are expected to remain below the Level 1 Acceptance Criteria during operation up to and Including the next power ascension plateau at 1753 MWL A summary of the changes to the models and the uncertainty evaluation, along with the new Steam Dryer Strain Gage Limit Curves Is contained In the Steam Dryer Monitoring Plan (SDMP) (Attachment 1 of BVY 06-031).

Thie details of these analyses, including any proprietary documents, have been made available to the NRC Technical Staff for review.

Page 2 of 3 The changes made to the steam dryer models and generation of revised steam dryer limit curves have been assessed against the requirements of License Condition 3.M.4 which states:

"When operating above OLTP, the operating limits, required actions, and surveillancesspecifiedIn the SDMP shallbe met. The following key attributesof the SDMPshafi not be made less restrctive withoutpdorNRC approval:

a. During Initial power ascension testing above OLTP, each test plateau Increment shall be approximately80 MWt;

b. Level I performance criteria;and

c. The methodology for establishing the stress spectra used for the Level 1 and Level 2 performance criteria.

Changes to other aspects of the SDMP may be made in accordance with the guidance of NEI 99-04."

As described above, License Condition 3.M.4 specifies those attributes of the approach to steam dryer monitoring that require NRC approval prior to being made less restrictive.

As addressed below, Vermont Yankee concludes that the key attributes have NOT been made less restricted and, therefore, the proposed model and limit curve changes do NOT require NRC approval.

The following changes have been Incorporated into the VY approach to steam dryer" monitoring:

1. Incorporation of strain gage accuracy Improvements In accordance with License Condition 3.M requirements.

2. Use of an updated CDI Acoustic Circuit Model (ACM) that has been modified to be conservative In the areas of Interest and benchmarked against Instrumented dryer data from several power levels at Quad Cities. The ACM update to address Industry operating experience is required by the License Condition.

3. Revisions to the Finite Element Model (FEM) to incorporate refinement of model in areas of concern related to past failures at Quad Cities and Dresden as required by the License Condition.

4. Generation of a new Uncertainty Calculation based on plant data and the changes above as required by the License Condition.

5. An updated Level. 1 Limit Curve representing a conservative reduction of the ASME design limit (13.6 ksi) by the values obtained in the uncertainty assessment.

6. There have been no changes to the Computation Fluid Dynamics (CFD) Model or the role of the CFD analysis to provide additional conservatism for low frequency flow sources.

i Page 3 of 3 This revision of the SDMP was evaluated against the criteria in Ucense Condition 3.M.4 to determine If NRC approval Is required as summarized below:

a. This revision proposes no change in the test plateau Increments from those specified In the criteria.

b. The Level 1 performance criteria Is defined as a limit curve for strain gage results that represents a stress on the dryer equal to the ASME Design Umit of 13.6 ksi minus the calculated total model and measurement uncertainty.

The application of model refinements that provide for higher accuracy in determining Vermont Yankee specific dryer stress limits does not constitute a change In methodology. The updated limit curves still represent the ASME criteria minus the calculated uncertainty.

c. The methodology for establishing stress spectra for the Level 1 and Level 2 criteria Is not altered by this change.

As required by Ucense Condition 3.M the output of the strain gages Is generated as Input to the Acoustic Circuit Model (ACM) analysis. The ACM generates pressure loads on the Steam Dryer using the Helmholtz equations. The ANSYS FEM code is used to generate stress loads for affected components of the dryer.

The above changes were evaluated using the guidance provided In NEI199-04.

Conclusion:

1. Based on the analysis performed using VYNPS Strain Gage data taken at the 1673 MWt plateau and employing the Improved models as required by the EPU LUcense Amendment the VYNPS Steam Dryer Is not expected to reach Level I Acceptance Criteria prior to or at the next power ascension plateau (1753 MWt) and Power Ascension can continue.

2. The SDMP has not been made less restrictive by the changes made to the ACM and FEM and prior NRC approval Is not required to implement these changes.

Preparer. Craig Nichols

, 0-I'--I Name 4 Signature Date Reviewer: James Callaghan J C1"*0,C Name £- SigrI*-u Date Reviewer James DeVincentis 0" Name Signature Date

April 5, 2006 MEMORANDUM TO: Darrell J. Roberts, Chief Plant Licensing Branch 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM: Kamal A. Manoly, Chief IRA!

Engineering Mechanics Branch Division of Engineering Office of Nuclear Reactor Regulation

SUBJECT:

STAFF TECHNICAL BASIS FOR CONTINUED POWER ASCENSION OF VERMONT YANKEE NUCLEAR POWER STATION UP TO 110% ORIGINAL LICENSED THERMAL POWER (TAC NO. MD0263)

Introduction On March 2, 2006, the U.S. Nuclear Regulatory Commission (NRC) approved the request by Entergy Nuclear Operations, Inc. (Entergy) to increase the maximum authorized power level for Vermont Yankee Nuclear Power Station (Vermont Yankee) from 1593 Megawatts thermal (MWt) to 1912 MWt as an extended power uprate (EPU) equivalent to 120%. of the original licensed thermal power (OLTP). During the subsequent power ascension at Vermont Yankee, plant instrumentation reached an initial administrative limit that required the licensee to evaluate the plant data before continuing the power ascension. On March 26, Entergy submitted its justification for continued power ascension at Vermont Yankee up to 110% OLTP. The NRC staff has reviewed the licensee's justification for continued power ascension at Vermont Yankee. Entergy will need to justify power ascension beyond 110% OLTP based on its review of plant data collected up to that power level. A narrative of the NRC staffs review of the licensee's justification for continued power ascension at Vermont Yankee is provided below.

Background

Following receipt of the EPU license amendment, Entergy began to slowly increase reactor power above OLTP on March 4, 2006, at Vermont Yankee in accordance with its power ascension test procedure. The EPU amendment included a license condition that provides for monitoring, evaluating, and taking prompt action in response to potential adverse flow effects as a result of power uprate operation on structures, systems, and components (including verifying the continued structural integrity of the steam dryer) at Vermont Yankee.

CONTACT: Thomas G. Scarbrough, DCI/CPTB 301-415-2794 Exhibit 2

D. Roberts 2 The Vermont Yankee power ascension procedure specifies that (1) the .power ascension rate be no-more than 16 MWt per.hour; (2) steam dryer performance data be monitored hourly and

-compared to acceptance criteria; (3) power level be held for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> at each 40 MWt step (2.5% OLTP) to obtain and evaluate additional plant performance data; and (4) power level be held for 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />s-at each 80 MWt plateau (5% OLTP) to conduct plant walkdowns and to perform steam dryer analysis with NRC staff review. Entergy has made a regulatory commitment to not increase power at Vermont Yankee ifthe NRC staff identifies a safety concern during its evaluation of the plant data.

As part of the plant data evaluation, Entergy collects Main Steam Line (MSL) strain gage data to monitor pressure fluctuations within the main steam flow. The licensee inputs the MSL strain gage data into an acoustic circuit. model (ACM) to calculate pressure loads on the steam dryer.

and the resulting stress in steam dryer components using a finite, element model (FEM). The Vermont Yankee Steam Dryer Monitoring Plan (SDMP) establishes a Level 1 limit curve for the MSL strain versus frequencyspectra based on the American Society of Mechanical Engineers (ASME) Boiler& Pressure Vessel Code (Code) fatigue stress limit of 13,600 pounds per square inch (psi), and a Level 2 limit curve based on 80% of that fatigue limit. Ifthe Level 2 limit curve is reached, the SDMP specifies that power ascension be suspended until an engineering evaluation concludes that further power ascension is justified. If the Level I limit curve is reached, the licensee must reduce power until the curve is not exceeded.

On- March 5, Entergy notified the NRC staff that the MSL strain gage data from the "An MSL at Vermont Yankee had reached the Level 2 limit at 105% OLTP. Entergy's evaluation of the MSL strain gage and accelerometer data concluded that it was acceptable to maintain plant operation at 105% OLTP while the engineering evaluation was performed. The NRC staff independently evaluated the 105% OLTP data, and concluded that continued plant operation at 105% OLTP was reasonable and acceptable.

Licensee Justification for Power Ascension up to 110% OLTP On March 26, 2006, Entergy completed its engineering evaluation of the Vermont Yankee steam dryer and its justification for continued power ascension to 110% OLTP. The engineering evaluation used (1) an improved ACM that is more bounding of actual steam dryer loads with reduced uncertainty; (2) an updated FEM that refines the assessment-of the gusset shoe area that was of concern in a similar steam dryer at the Dresden nuclear power plant; (3) a more precise MSL strain gage data acquisition system designed to reduce the measurement uncertainty in the acoustic signals; and (4) MSL strain gage data collected at 105% OLTP.

Entergy verified that the stress in the Vermont Yankee steam dryer components remains significantly below the ASME Code fatigue stress limit of 13,600 psi at 105% OLTP. Further, the reduced uncertainty in the ACM and the MSL strain gage data acquisition system allowed Entergy to raise the limit curve for the MSL strain gage measurements while maintaining the resulting stress in the steam dryer below the ASME Code fatigue stress limit. The new limit curve has been incorporated into a revision of the Vermont Yankee SDMP.

D. Roberts 3 Based on its engineering evaluation, Entergy has determined that continued power ascension to 110% OLTP will not cause stress exceedance in the steam dryer components that would challenge the structural integrity of the dryer.

NRC Staff Evaluation

The NRC staff, with support from its consultants from Argonne National Laboratory, has reviewed Entergy's engineering evaluation consisting of multiple analyses, data, and figures.

The staffs review of the licensee's generic application of uncertainty assumptions for the revised ACM and improved MSL strain gage instrumentation is continuing. At this time, the staff has evaluated the licensee's basis for continued power ascension at Vermont Yankee up to 110% OLTP, including the calculation of the stresses on the steam dryer components at 105% OLTP and the establishment of new limit curves for MSL strain gage data in support of operation up to 110% OLTP.

The Vermont Yankee steam dryer analysis indicates that the steam dryer gusset shoe area is the most limiting stress location on the Vermont Yankee steam dryer for EPU operation. The stress on this component at 105% OLTP is calculated to be 2321 psi from the ACM and 599 psi from the Computational Fluid Dynamics (CFD) analyses. If the MSL strain gageameasurements increase up to the new Level 1 limit curve in all four steam lines, the stress at this location is.

projected to be 9866 psi. This stress is about 40% less than the ASME Code fatigue limit of 13,600 psi. The Vermont Yankee SDMP provides additional margin in that power ascension must be halted and the collected data evaluated if any portion of the measured MSL strain-frequency spectra reaches the Level 2 limit (80% of the 13,600 psi limit) for any of the four steam lines.

As part of its review, the staff compared the Vermont Yankee MSL strain gage limit curves established for initial power ascension to the new limit curves based on the revised ACM and more accurate MSL strain gage data. Although the new limit curves permit a higher MSL strain gage signal than the initial curves, the allowed MSL strain levels continue to be low. Higher strain peaks at the resonance frequencies experienced at 105% OLTP were acceptable to be included in the limit curve based on their insignificant contribution to the total resulting stress:

Since the only instrumented steam dryer among the operating U.S. boiling water reactors is that at Quad Cities Unit 2 and the original steam dryers at Quad Cities were the only dryers at U.S.

plants that have experienced severe damage under EPU conditions, the revised Level I limit curve for Vermont Yankee was compared to the MSL data measured at Quad Cities Unit 2.

The comparison indicated that the Vermont. Yankee revised Level 1 limit was significantlybelow the MSL data measured at Quad Cities Unit 2. Further, the Vermont Yankee SDMP will require the licensee to halt power ascension if any acoustic signal from the Vermont Yankee MSL strain gage data in any MSL reaches the Level 2 limit curve, which is 80% of the Level I limit curve.

With respect to the low-frequency regions of MSL strain gage data, the staff will ensure that Entergy closely monitors those low frequency areas during future power ascension where the Vermont Yankee Level I limit curve is above the measured-Quad Cities Unit 2 MSL data.

D. Roberts 4 The NRC staff is reviewing the recently identified cracking in the skirt region of the steam dryer at Quad Cities Unit 2. The Quad Cities licensee has initiated an extensive effort to determine the cause of the cracking. Prior to the current outage, Quad Cities Unit 2 operated at up to 117% of the original licensed power for about 6 months with substantial high-frequency acoustic loads on the steam dryer. Entergy has evaluated the applicability of the Quad Cities Unit 2 information to Vermont Yankee. The staff reviewed Entergy's evaluation of the applicability of the Quad Cities Unit 2 steam dryer cracking to Vermont Yankee. Entergy applied a more conservative damping assumption in its assessment of the steam dryer skirt at Vermont Yankee than that used at Quad Cities. Even with this more conservative damping assumption, the stress in the skirt region of the Vermont Yankee steam dryer is calculated to be less than 1000 psi at 105% OLTP. Therefore, there is considerable margin in the stress analysis for the skirt region at Vermont Yankee to account-for damping and other assumptions. The staff does not consider the cracking in the skirt region of the Quad Cities Unit 2 steam dryer to raise a safety concern with power ascension at Vermont Yankee up to 110% OLTP.

Conclusion Based on its review of the Entergy's engineering evaluation, the NRC staff concludes thatthe licensee has provided a reasonable basis for continuing power ascension up to 110% OLTP at Vermont Yankee, including (1) plant performance limit curves that maintain MSL strain gage data far lower than the Quad Cities data in the high-frequency acoustic range; (2) frequent monitoring of plant performance data, including hourly collection of the MSL strain gage data; and (3) plant procedures that halt power ascension if any portion of the measured MSL strain vs. frequency spectra reach the Level 2 limit curve for any Vermont.Yankee MSL. On March 31, 2006, the NRC staff informed Entergy that the staff did not object to the continued power ascension process at Vermont Yankee up to 110% OLTP. The staff will continue to discuss the steam dryer analysis and its assumptions with Entergy as part of the review of the revised ACM for generic use at Vermont Yankee and other nuclear power plants. The staff will ensure that Entergy closely monitors the MSL strain gage data for any increases toward the limit curves during the power ascension at Vermont Yankee. The staff will review Entergy's justification for continued power uprate operation, including further power ascension, based on the plant data collected during this next power ascension step..

D. Roberts 4 The NRC staff is reviewing the recently identified cracking in the skirt region of the steam dryer at Quad Cities Unit 2. The Quad Cities licensee has initiated an extensive effort to determine the cause of the cracking. Prior to the current outage, Quad Cities Unit 2 operated at up to 117% of the original licensed power for about 6 months with substantial high-frequency acoustic loads on the steam dryer. Entergy has evaluated the applicability of the Quad Cities Unit 2 information to Vermont Yankee.' The staff reviewed Entergy's evaluation of the applicability of the Quad Cities Unit 2 steam dryer cracking to Vermont Yankee. Entergy applied a more conservative damping assumption in its assessment of the steam dryer skirt at Vermont Yankee than that used at Quad Cities. Even with this more conservative damping assumption, the stress in the skirt region of the Vermont Yankee steam dryer is calculated to be less than 1000 psi at 105% OLTP. Therefore, there is considerable margin in the stress analysis for the skirt region at Vermont Yankee to account for damping and other assumptions. The staff does not consider the cracking in the skirt region of the Quad Cities Unit 2 steam dryer to raise a safety concern with power ascension at Vermont Yankee up to 110% OLTP.

Conclusion Based on its review of the Entergy's engineering evaluation, the NRC staff concludes that the licensee has provided a reasonable basis for continuing power ascension up to 110% OLTP at Vermont Yankee, including (1) plant performance limit curves that maintain MSL strain gage data far lower than the Quad Cities data in the high-frequency acoustic range; (2) frequent monitoring of plant performance data, including hourly collection of the MSL strain gage data; and (3) plant procedures that halt power ascension if any portion of the measured MSL strain vs. frequency spectra reach the Level 2 limit curve for any Vermont Yankee MSL. On March 31, 2006, the NRC staff informed Entergy that the staff did not object to the continued power ascension process at Vermont Yankee up to 110% OLTP. The staff will continue to discuss the steam dryer analysis and its assumptions with Entergy as part of the review of the revised ACM for generic use at Vermont Yankee and other nuclear power plants. The staff will ensure-that Entergy closely monitors the MSL strain gage data for any increases toward the limit curves during the power ascension at Vermont Yankee. The staff will review Entergy's justification for continued power uprate operation, including further power ascension, based on the plant data collected during this next power ascension step.

DISTRIBUTION:

DCI r/f Mmayfield Elmbro

• previously concurred ADAMS NO.: ML060970111 NAME TScarbrough ICWu Kman°'

DATE 04/04/06. 0405106 04105/06 OFFICIAL RECORD COPY

April 7, 2006 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-II-06-010 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region III staff on this date.

Facility Licensee Emergqency Classification Exelon Generation Co. __ Notification of Unusual Event Quad Cities 2 _ Alert Cordova, IL __ Site Area Emergency Docket: 50-265 _ General Emergency License: DPR-30 X Not Applicable

SUBJECT:

CRACKING IDENTIFIED IN UNIT 2 STEAM DRYER DESCRIPTION:

The licensee has identified cracking in the Unit 2 steam dryer during the unit's ongoing refueling outage. The steam dryer is an internal reactor structure designed to remove moisture from steam before it enters the main steam lines to the turbine. The steam dryer was installed in May 2005 as the first steam dryer replacement in a U. S. reactor.

The steam dryers for both Quad Cities units were replaced because of cracking concerns caused by acoustic loading and vibration from operation at Extended Power Uprate power levels. The replacement dryers were designed and constructed to be more robust and resistant to cracking than the previous steam dryers. The Unit 2 steam dryer was also instrumented with several strain gauges, pressure transducers, and accelerometers.

The initial inspection by the licensee revealed one large crack, approximately 5 feet in length, with multiple branches, in the skirt region of the dryer. This crack is currently believed to have been caused by binding difficulties experienced during the initial installation last year, but the root cause evaluation is still in process. The Unit 2 dryer installation lessons learned were incorporated into the Unit 1 steam dryer installation, and no difficulties were experienced with its installation.

The licensee has also identified several smaller cracks of lesser significance on various internal bracing within the dryer. The steam dryer inspection is expected to be completed on April 9.

Evaluations of all of the cracks and indications also are continuing, and the licensee is developing plans to repair the steam dryer. Region III (Chicago) and the NRC Resident Inspectors are monitoring the licensee's activities.

The State of Illinois will be notified. The information in this preliminary notification has been discussed with licensee management.

Exhibit 3

Region III received initial notification of the steam dryer inspection findings on March 29, 2006, and additional information was provided as the inspection has continued. This information is current as of 1:45 p.m. CDT on April 7, 2006.

CONTACTS: Allan Barker Mark Ring 630/829-9679 630/829-9703

SM Nuclear Quad CitAies Unit 2 (QC2)

Dryer Update April 10, 2006 1

Exhibit 4

NucleaT Introduction Patrick Simpson Licensing Manager 2

Agenda nM Nuclear

• Background Tim Hanley Dryer Inspection Results D Tim Hanley

• Preliminary Cause Roman Gesior

• Repair Strategy Tim Hanley

• Conclusions/Outage Status Randy Gideon 3

Nuclear

Background

Tim Hanley Director Midwest Operations Projects 4

Background n lorI ,nM Nuclear Lifting Eye (1 of 4)

Dryer Configuration Dryer Banks (Vane Assemblies) Lifting Rod

/ (1 of 4)

-Dryer Guide Slots Cut Out for Reactor Vessel Support Dryer Upper Support (1 of 4) Ring 5

Background (cont.) r Nuclear

• QC2 replacement dryer was installed in May 2005

- During fabrication some ovality was created in the skirt section of the dryer

• During the installation, an interference was encountered with the separator guide rods that prevented the dryer from fully seating 0 During the removal of the dryer to correct the interference the dryer impacted the dryer support lugs that are attached to the inside of the reactor vessel at the 1400, 2200, and 3200 locations

- Cause: lack of clearance between the skirt base ring/reactor vessel support lugs and excessive clearance between dryer guide rods/dryer 0 Indications of deformation at 1400, 2200, and 3200 locations were observed at this time

• Subsequent inspections during the current refueling outage revealed additional indications at these locations

- Deformation of the skirt base ring on the IDat 1400 and 2200 locations

- Skirt panels dimpled at.1400 and 2200

- Neither of these conditions were observed at the 3200 location 6

Background (cont.)

Original Deformation Nuclear 7

Background (cont.)

Nuclear

• Deformed areas were non-destructively (PT) examined on the OD and skirt base ring with no indications identified and dispositioned as acceptable for use for one cycle

• Repairs, modifications, and inspections of these areas, were planned to be implemented during current refueling outage

• QC1 replacement dryer was installed in May 2005

- Based on QC2 lessons learned avoided ovality and installation issues 8

Nudear Dryer Inspection Hesults Tim Hanley Director Midwest Operations Projects 9

Drer Inspection Results NucleaT

• QC2 dryer inspections have been completed

• Inspection scope encompassed and exceeded the requirements of BWRVIP-139

- Inspections a combination of VT-1 and VT-3

- General exterior visual examination

- Locations potentially subject to fatigue

- Outer structural. welds including:

• Hoods, vanes, skirt, upper support ring, skirt base ring

- Inner structural welds including:

• Cross beams (to upper support ring and support castings)

- Drain channels and tie bar welds

• Scope expansion:

- Skirt plates

- Skirt base ring cut-outs, gussets

- Latch boxes 10

Dryer Inspection Results (cont.) O'\T n Nuclear 1.4 total indications documented in Indication Notification Reports (INRs)

- 7 indications were minor in nature with no structural significance:

• 2 documented the re-inspection of the deformed areas at the 2200 and 3200 location with no changes noted

• 2 documented surface anomalies that were classified as non-relevant 1I documented a small piece of debris that is captured in the dryer intemals (less than 2/10" in length)

° 1 documented damage to the 200 area at the separator guide rod cut. out that required minimal repair

• 1 documented deformation to perforated plates 11

Dryer Inspection Results (cont.) E791 rm Nuclear The following .7 indications will be discussed:

3 documented small cracks in the end vane in three vane assemblies (INRs 06-06, 06-08, and 06-10) 1 documented the rotation of the lifting eyes and damage to the lifting rod threads (INR 06-01) 1 documented a crack in the latch box located at the 2200 location (INR 06-29)

- 1 documented a crack in the vane assembly end plate near the 3200 location (INR 06-04)

- Idocumented a large crack in the dryer skirt and base plate at the 1400 location (INR 06-02) 12

Dryer Inspection Results (cont.)

mm Sm Nuclear

,Separator Guide Cutout (2 Locations)

Reactor Vessel Support Lugs (4 Locations) 06, 08, 10 900 Skirt Crack INR 06-02 Latch Box Crack 180f INR06-29 13

Dryer Inspection Results (cont) x Nuclear Dryer Vane Bank Assembly JINRs 06-06, 06-08, and 06-10 document minor indications in the vane bank assemblies for.

dryer banks F, D, and B, respectively SArrows indicate areas of cracking 14

Dryer Inspection Results (cont.) e Nuclear Small cracks in the end vane in various vane assemblies (INRs 06-06, 06-08, and 06-10)

- Characterized as fatigue cracking

- Located in the end vane in their respective vane assembly which is wrapped around and welded to the end plate (non-structural)

- Indications appear to have initiated from the hole in vane that accepts 5/8" tie rod protector

- Dispositioned as no repair required - will be inspected during the next refueling outage

- Missing material cannot be confirmed -to be lost in the vessel -

conservatively captured. by lost parts program

° Applicability to QC1 Not a concern due to the small size of the cracks and lack of a driving force at that location

- Cracks expected to be self relieving

-- Will be inspected during the upcoming planned outage 15

Dryer Inspection Results (cont.)

NucleaT Dryer Liftingq Eye Assembly

• INR 06-01 documented Setscrew Hole lifting eye rotation and lifting rod thread damage 0.

3" Lift Rod Rod Guide Fixture Dryer Lifting Eye Assembly 16

D enspection Results (cont.)n Nuclear Rotation Of the lifting eyes and damage to the lifting rod threads (INR 06-01)

- Four lifting eyes were found rotated out of alignment

- Damage to the threads in the lifting rod at the 450 location

• Cause - installation issues with the setscrew in addition to an inadequate setscrew design that allowed the eyes to rotate with setscrew in place and tack weld intact

• Corrective action - unthreaded stock at the top of the lifting rod is being ground flat and a longer set screw is being added to ensure positive engagement Applicability to QCl

- Lifting eyes on QC2 dryer-were removed after initial attempt to engage lifting rig and reinstalled - not required on QC.

Lifting eye unlikely to separate from lifting rod due to unthreaded area at the top of lifting rod

- In the unlikely event the. lifting eye came off of the lifting rod, lost parts analysis has concluded that it would not prevent a safety function

- Will be inspected during the upcoming planned outage 17

7.

Dryer Inspection Results (cont.) ý,,1.7

"(--)

!aT Latch Box

• INR 06-29 identified crack in latch box 18

Dryer Insp ection. Results (cont.)

Nuclear Crack in the latch box at 2200 location (INR 06-29)

- Function of the latch box is to limit bypass flow from the inside of the dryer skirt to the downcomer region Non-structural component

- Located on the same azimuth that was stressed during the impact event Characterized as fatigue cracking Other three latch boxes and welds were inspected with no issues identified

- Repair consists of excavating cracked area and re-welding

• Applicability-to QC1

- QC1 dryer did not experience an impact event

- Non-strUctural

- Will be inspected during the upcoming planned outage 19

-MD Dryer Inspection Results (cont.) sm INR 06-04 Vane Assembly Nuclear 20

Dryer Inspection Results (cont.) E-M, ý SM

, m mNucleaT

• Crack in the vane assembly end plate near the 3200 location (INR 06-04)

- Located on same azimuth of the dryer that experienced skirt base ring damaged during the impact event

- Crack is in the bottom 2 inches of a -6 foot weld

- Characterized as fatigue cracking with a combination of bending and torsional loading

- Inspection identified an abrupt change in weld thickness at the crack location

- Similar locations inspected with no cracks identified nor were any other cases of abrupt changes in weld thickness identified

- Not a loose parts concern due to attachment to other dryer members

- Dispositioned as no repair required - re-inspect during the next refueling outage

• Applicability to QCl

- QC1 dryer did not experience an impact event

• Isolated to this one location in QC2

- Not a lost parts concern

- Will be inspected during the upcoming planned outage 21

Dryer Inspection Results (cont.)

INR 06-02 Dryer Skirt Nuclear

!2

Dryer Inspection Results (cont.) E7eO Nuclear Crack in the dryer skirt and base ring at the 1400 location (INR 06-02)

- Approximate.6 foot crack extends from a cutout in the base ring into. the adjacent skirt

• Crack affected area was below the normal reactor water level

-. Boat samples taken in four locations for analysis

• Preliminary cause indicates impact event key contributor Applicability to QC1

- QC1 dryer did not experience an impact event

• Ovality issues were addressed prior to manufacturing Lost parts analysis concluded that if a lost part were generated would not compromise a safety function 23

Nuclear Preliminary Cause Roman Gesior Corporate Programs Director 24

Preliminary Cause eJ NucleaT Multi-disciplinedlteam used to determine cause of dryer damage

• Tools being used to determine cause of failure

- Metallurgical failure analysis

- Dryer inspection results and observations

- Stress analysis

- Failure Modes and Effects Analysis (FMEA)

- Event and causal factor chart Conclusions C

-. Load on skirt base ring during impact event induced damage while plastically deforming skirt base ring and skirt plate; o Reduced the fatigue endurance

• Residual stresses from fabrication were also a contributor Operating pressure oscillation loads from Main Steam Line (MSL) acoustics resulted in skirt/base ring stresses that when combined with the reduced fatigue endurance was adequate to propagate cracking

Peliminary Cause NucleaT

• Other causes investigated:

- Design e Adequacy of FEA

° Applied Loads/damping 4 New design

- Base ring cutouts

- Fabrication

• Fit-up/sequence of fabrication

• Base ring distortion

• Materials issues

- Installation

• Decision making after fit-up

• Impact with separator guide pins

• Load cell not functioning

- Operating transients 26

Preliminary Cause (cont.)

Metallurgical Analysis S1400 Location Nuclear 27

Preliminary Cause (cont.)

Metallurgical Analysis xM NucleaT

• .Sample analysis results

- Scanning Electron Microscope (SEM) results

-show surfaces-are characteristic of fatigue

- Fracture surface near the IDof the skirt base ring is consistent with -torsional fatigue

- No evidence of cold work induced stress corrosion cracking No evidence of ductile tearing

- Initiation site has not been identified

- Secondary cracks that connect with the main fracture emanate out of weld root 28

Preliminary Cause (cont.)

Metallurgical Analysis Ft 7 z- SM Nuclear

- Weld details require ID and OD penetration of 0.16" with 0.1" fillet reinforcement

• As built configuration has significant fillet reinforcement and weld size not cause of failure 29

Preliminary Cause (cont.)

Metallurgical Analysis enSM Nuclear Crack in the dryer skirt and base ring (140' location)

- Impact event induced a large torsional load (>47,000 pounds) in the skirt base ring and bending load in skirt plate Load on base ring at reduced section (due to cut-out area) resulted in localized high stress

- The load resulted in plastic deformation of skirt base ring and skirt plate (dimples on skirt plate)

- The plastic deformation of the base ring and skirt plate reduced the fatigue endurance limit of the material

- Pressure oscillation loads from MSL acoustics provided cyclic stress necessary to propagate crack

• The operating loads would also produce a torsional load on the base ring through the support gusset 30

Preliminary Cause (cont.)

Dryer Pressure and Strain Measurements Nuclear

• Pressure oscillation loading alone at 1400 location would not have initiated a fatigue crack

-- Other azimuths of dryer (MSLs C and D) with less plastic

• deformation had no cracking

• Similar configuration

• Higher pressure loading than the side that cracked (MSL B)

- Skirt flat plate adjacent to MSLs has significantly higher pressure loads - however no cracking

• Based. upon in plant measurements

• Area of skirt base ring cracking was the most significantly deformed during the impact event

" Examination.of the skirt at this location indicates dimpling

" The impact event resulted in residual stresses that reduced the endurance of the dryer skirt/base ring plate 31

Preliminary Cause (cont.)

Dryer Pressure and Strain Measurements En Nuclear Skirt pressure transducers

-P22, P24, and P25 Skirt strain gages

- S8, S1, and S2 "A" Hood pressure transducers P3, P12, P15, and P17 "B" Hood pressure transducers P20 and P21 psi Max-Min Instrument (ms) psi P3 (90) 0.631 3.704 P12 (70°) 0.690 3.976 P15 0.547 3.192 P17

• 01232 1.550 P20 (2500) 0.499 3.201 P21 (2900) 0.883 4.360 P22 0.422 2.622 P24 0.225 1.595 P25 0.344 2.436 32

Preliminary Cause (cont.)

Dryer Pressure and Strain Measurements Nuclear Dryer Orientation-VmMR Banks A - F Main Steam LinesC 33

Preliminary Cause (cont.)

Dryer Pressure and Strain Measurements O'e nS Nuclear Dryer pressure load becomes smaller moving down from steam nozzles

- Lowest outer hood pressure of 3.2 psi is greater than largest skirt pressure of 2.6 psi

- Skirt pressure drops from 2.6 psi to 1.6 psi from P22 to P24 lower on skirt

• Pressure loads also drop when moving circumferentially away from the nozzles

- Circumferential trend away from MSL P12 = 3.98 psi to P15 = 3.19 psi to P17 = 1.6.psi

• Pressure is lower on 140' (MSL B) dryer side than 40. (MSL A) or'3200 (MSL D) dryer side

- P3 (MSL B) = 3.7 psi is less than P12 (MSL A) = 3.98 psi and P21 (MSL D).= 4.36 psi 34

Preliminary Cause (cont.)

Dryer Pressure and Strain Measurements NucleaT Pressure measurements alone would indicate that the skirt is more susceptible at-a different location

- Cracking occurred at location of low measured pressure

- Indicates that the residual stress due to impact event is a larger contributor than the acoustic pressure oscillation

- Therefore, cracking occurred at 1400 location due to increased plastic deformation and residual stress

• Condition of high stress locations on dryer with no cracks supports applied loads are conservative

• Number of fatigue cycles at EPU operation (>200 days) with 155 Hz load would have resulted in cracks at this location if stresses exceeded endurance limit

• No dryer degradation at 40* azimuth where dryer did not get hung up on RPV wall support 35

Preliminary Cause (cont.)

Finite Element Model NucleaT 2005 evaluation of impact event

.,Stress identified in the evaluation was extremely low and therefore the deformation residual stress was not considered an issue Stress levels under-predicted due to simplistic modeling of dryer skirt base ring plate

° Cutout not included

• Skirt base ring support gusset was not included

- Recent model update with solid elements including_ cut-out and gussets indicate that the cycle operating stresses are low (<30% of endurance limit)

- PT inspections of the deformed areas did not include the dryer ID

- An analysis was not performed to. characterize the stress level or dryer loading due to the dryer being hung up

• PT inspection. results provided condition assessment that material tensile stresses were not exceeded 36

Preliminary Cause (cont.)

Conclusions n,*

NucleaT Load on skirt base ring during impact event induced damage while plastically deforming skirt base ring and skirt plate Reduced the fatigue endurance Residual. stresses from .fabrication were also a contributor

° Operating pressure oscillation loads from MSL acoustics resulted in skirt/base ring stresses that when combined with the reduced fatigue endurance was adequate to propagate cracking 37

Nuclear Repair Strategy Tim Hanley Director Midwest Operations Projects 38

Repair Strategy Nuclear

• 1400 and 2200 locations

- Removed a portion of skirt base ring and skirt panel and replaced with plates of the original dimensions

- Cutout size: --26" by ~40" for the 1400 skirt section

- Similar repair was made at the 2200 location; however, height is only 12 inches, which removes all deformation that was measured in the dryer skirt

- Restores dryer to as close to original design configuration as possible

• 3200 location

- Major portion of the deformed base plate was already being removed at the 3200 location as part of the original modification to address the cause of the impact event 0 Removing skirt ring gussets at all four locations 0 These changes to the dryer. have been independently reviewed by a third party 39

NucleaT Conclusions/Outage Status Randy Gideon Plant Manager 40

Conclusions Nuclear

" Replacement dryer design is robust

" Cracking that occurred. in the skirt and base ring would not have occurred without the impact event

° Remainder of indications are not structurally significant

° Design enhancements and repairs have been analyzed and' independently reviewed

• Dryer inspection results demonstrate replacement dryer design is sufficient to accommodate EPU operation 41

LS-AA-125-1001 Revision 5

Title:

Q2R18 Concerns Related to Steam Dryer Unit(s): Quad Cities Unit 2 Event Date: 03/29/2006 Event Time:

Action Tracking Item Number: 472321-03 Report Date: 05/16/2006 Sponsoring Manager: Tim Hanley, Exelon Nuclear Corporate Manager Exelon Corporation Investigators & Exelon Contracted Contributors:

Roger Armitage & Steve Boline, Quad Cities RC Team Leads Alan Lewis, Quad Cities Engineering (RC Investigator Qualified)

Bhausaheb Shete, Dresden Engineering (RC Investigator Qualified)

Karl Adlon, Quad Cities Engineering Joe Sipek, Dresden Engineering Programs Manager Jeff Miller, Clinton Engineering Programs Manager Chris Cooney, Kennett Square Engineering Dave Haberkorn, Quad Cities Operations Matt Dreyfuss, Kennett Square Engineering Bill McDonald, LaSalle Engineering Pete Shier, Byron Engineering Guy DeBoo, SME Exelon Engineering, Cantera David Melear, Engineer, ILD Inc.

Robert Stackenborghs, Engineer, ILD Inc.

General Electric Corporation (GE) Investigation Team (see Ref. 21 for full list):

Robert Gamble, SME GE RC Team Rowland Linford, GE RC Team Lead N:APUBLIC\ýQuad Cities Q2RI 8 Dryer\!Final RCA Docs\l!RCR Dryer Final no Att.doc Exhibit 5

Table of Contents Section EPage I. Executive Summary 3-4 III. Condition Statement 5 HL. Event Description 6-12 IV. Analysis 13-20 V. Evaluation A. Table.of Causal Factors 21 B. Discussion of Basis for Cause Determination 23 C. Discussion of Evaluation of Other Conditions 30 VI. Extent of Condition 35 VII. Risk Assessment 36 VIII. Previous Events 37 IX. Corrective Actions to Prevent Recurrence 37 X. Corrective Actions 38 XI. Effectiveness Reviews 38 XII. Programmatic/Organizational Issues 39 XIII. Other Issues 42 XIV. Communication Plan 43 Figures:

1. General Steam Dryer Configuration F. I

.2. Schematic of Steam Dryer of Base Ring to RPV Lug Orientation F. 2 Attachments:

1. Event and Causal Factors Chart A. 1-2

2. Event Timeline A. 3-4

3. References A. 5-7

4. Comparison: QC 2 Replacement Dryer Pressure Sensor Data A. 8-10 with Q2R18 Dryer Damage.

5. Failure Mode Tree - Dryer Skirt Crack/Deformation A. 11-20

6. Failure Mode Tree - Dryer End Plate Cracks A. 21-24

7. Dryer Lift Event Description and Pictures A. 25-34

8. Table of Q2R18 INRs/IRs A. 35 9: CA's from ERV Actuator RCA Aligned with CF2 of.Q2R18 A. 36-37 Steam Dryer RCA 10: Root Cause Quality Checklist A. 38-39 Page 2 of 43

I. Executive Summary:

During the planned in-vessel visual inspection (IVVI) of the Quad Cities Unit 2 (U-2) reactor steam dryer at the beginning of refueling outage Q2R18, a crack was discovered in the dryer skirt at the 1400 azimuth location. At the completion of all dryer inspections, cracks were discovered at various locations in the dryer assembly including the dryer skirt base ring, a vane bank end plate, chevron plates, and a latch box. Several of these cracks occurred in areas adjacent to one of the two areas most severely deformed during removal of the dryer in May 2005.

This Root Cause Analysis (RCA) investigation scope was focused on determining the causes of the dryer assembly cracking in the dryer skirt plate, the vane bank endplate, and the latch box assembly.

RCA investigation into the events associated with the design, fabrication, installation and operation of the steam dryer identified a series of factors that, when taken in aggregate, are the causes for the formation of the identified cracks. The causes for each of the three cracks included in the scope of this RCA is summarized below:

1. Steam Dryer Lower Skirt Crack at 140': The root cause for this cracking is related to deformation caused when the dryer skirt base ring caught on the reactor pressure vessel (RPV) dryer support lugs in May 2005 (referred to as the "lifting event"). The exact mechanism of initiation of the cracks could not be determined, however the RCA concludes that this event introduced significant plastic strains that reduced the material's fatigue endurance properties. When combined with the cyclic loadings that the dryer experiences during normal operation, fatigue cracking propagated through the skirt base ring and into the dryer skirt panels. The lifting event occurred as a result of changes in design of the installation hardware used in the replacement dryer. This change in installation hardware is considered a root cause.

These changes, combined with widened installation clearances introduced during dryer fabrication (referred to as "ovality") allowed for enough movement for the dryer to become damaged on the RPV support lugs during removal. The widened installation clearance introduced from fabrication ovality is also considered a root cause for the dryer skirt cracking.

2. Cracking in Gusset 19 of Vane Bank "E" at 3200: Root cause is: having very little weld metal between the end plates, proximity to a weld transition (Stress Riser), fabrication stresses due to hood assembly and weld shrinkage, and the presence of operating vibration loads.

3. Cracking in Latch Box at 220*: Root cause is: high residual weld stress from weld end discontinuity and the corner location.

Corrective actions include:

• Repair of the most severely damaged portions of the dryer skirt and base plate near the 1400 azimuth.

" Replacement of skirt and base plate material in the 220* azimuth area, which did not exhibit cracking but was considered to have similar potential crack initiating factors as the 1400 azimuth areas.

" Modification of the dryer base plate to reduce the potential for future lifting events.

e Modification of the dryer guide slots to reduce the potential for future lifting events.

" Repair of the crack in the dryer latch box at the 220* azimuth.

Page 3 of 43

Evaluation of the visual indications (crack) in the bank E drying vane end plate. Evaluation concluded that there was "adequate justification for continued operation of the steam dryer without repair of the cracking at the gusset to vane bank end plate locations ... " (Ref. 17)

Modified main steam relief valve branch lines with acoustic side branches to reduce dryer cyclic loads.

An extent of condition review included inspections of other susceptible areas of the steam dryer. All dryer cracking was reviewed in accordance with IVVI program requirements regarding actions required prior to restart from Q2R18, and appropriate inspections in future outages. The key analysis documents for these determinations are listed in Attachment 8 of this RCA. No other degradation similar to the three events in the scope of this RCA was identified. Analyses completed by General Electric (GE) and reviewed by Exelon determined that without the additional stresses and material degradation resulting from the May 2005 lifting event, the operational loads were not sufficient to initiate cracking in the U-2 dryer skirt plate. Therefore, similar cracking of the Unit 2 dryer is not expected to occur in the future.

In addition, the Unit 1 steam dryer, which did not experience either fabrication ovality or installation lifting events, did not exhibit similar cracking when inspected in the Q1M19 outage in May 2006.

The steam dryer degradation was not reportable, however the issue has been discussed with the Nuclear Regulatory Commission (NRC),. A risk assessment of the identified condition was performed and determined the consequences of this event had minimal impact on reactor safety. Although unanticipated structural cracking was identified in the dryer, the cracking did not represent an increase in risk to nuclear safety or off-site dose consequences. A Probabilistic Risk Assessment (PRA) evaluation found this event to be non-risk significant.

Page 4 of 43

I- Condition Statement:

During the planned IVVI in Q2R18, the RPV steam dryer was removed from the vessel and inspected.

Initial inspection revealed a branching crack in the dryer lower skirt area approximately 6 feet in total length at the 1400 azimuth location (Refs. 10&1 1). Subsequent inspections also identified cracking in the steam dryer vane bank end plate in the "E" bank (Refs. 12&13), and a crack in the lower right corner of one dryer latch box (Refs. 14&,15). These three conditions form the specific investigation scope requiring resolution in this.RCA, and are referred to in subsequent sections of the RCA as:

> Event 1: Steam.Dryer Lower Skirt Cracking near the 140' azimuth, identified in AR 472321.

> Event 2: Steam Dryer Cracking in Gusset 19 of Vane Bank "E" End Plate near the 3200 azimuth, identified in AR 473034.

> Event 3: Steam Dryer Cracking in Latch Box near the 2200 azimuth, identified in AR 475369.

Additional dryer cracking was identified during Q2R18, and although not specifically included in the scope of this RCA, all dryer cracking was reviewed and dispositioned in accordance with IVVI program requirements. Specifically, actions required prior to restart from Q2R18 were completed, and appropriate inspections in future outages were specified. The key analysis documents for these determinations are listed in AUt. 8 of this RCA.

Consequences & Significance: The dryer is a passive non-safety related component, however, it must remain structurally intact to preclude introduction of loose material into plant systems such that no safety-related systems, structures or components are prevented from performing their design basis safety function. Additionally, the dryer skirt must function as a boundary to maintain the basis for reactor water level sensing and protective actuations.- At the time of discovery, all dryer components, including the skirt, remained constrained within the dryer envelope and therefore, there was no safety significance to this event.

This report focuses on the equipment failure, the failure modes, and causal factors for the identified dryer issues. The failure of the skirt plate has the potential to generate debris, for which a lost part evaluation (Ref. 20 is the Lost Parts Evaluation for this condition) was completed for Unit 1 impacts.

This event is not considered a recurring problem since the Unit 2 dryer is a newly installed replacement.

OPEX reviews have not identified previous history with large cracking in dryer skirt plate material similar to that identified in Q2R18. Quad Cities Unit I has a similarly designed installed replacement dryer and Dresden Units 2 & 3 have similar replacement dryers that are not yet installed. These three additional dryers will be considered for extent of condition in this RCA.

Page 5 of 43

HI. Event

Description:

Note: This event description provides a chronological narrative of the sequence of events as they apply to this RCA. This section also includes "Notes" intended to highlight the significance of the information as it applies to the subsequent Analysis and Evaluation sections. Additional items included in this RCA report, which may assist in general understanding of the events, include:

Att. 1: Event and Causal Factors Chart.

Att. 2: Event Timeline Table.

Att. 3: List of References.

Fig. 1: General Steam Dryer Configuration Fig. 2: Schematic of Steam Dryer Base Ring to RPV Lug Orientation 2004 - Early 2005 Following several previous Quad Cities outages in which steam dryers were found with failed or degraded dryer elements, a decision was made to purchase and install new steam dryers in both units.

The steam dryer was fabricated and assembled at U.S. Tool and Die in Pittsburgh, PA under the direction of GE. Due to transportation limitations, the steam dryer could not be shipped in one piece in the required timeframe. This required that the dryer be fabricated as two assemblies that were shipped separately and then assembled locally.

Note: During the design and fabrication of the new Quad Cities steam dryers, several issues imposed constraints on the delivery of the first dryer for Quad Cities. Manufacturing delays necessitated that the dryer originally intended for Quad Cities U-1 installation during Q1R18, be delivered for installation in Unit 2 during Q2P03.

March 2005 The Unit 2 replacement steam dryer upper half (vane banks and support ring) and the skirt assembly were welded together at J. T. Cullen in Fulton, IL.

3/30/05 The Configuration Change Review Checklist (CC-AA-102 Attachment 10F) for the dryer modification EC351168 Revision 0 was signed by the Reactor Services department representative.

Note: This was the initial end user's review in the Exelon design process. This review is considered a "cross discipline" review and a barrier to prevent negative impacts of design changes. This review was documented after dryer fabrication was almost complete. This topic is discussed further in the evaluation section.

3/31/05 Inspection of the dryer at J.T. Cullen following assembly determined that the as-built dryer dimensions were outside the expected design tolerances. The diameter measured across the 00-1800 orientation measured 245", while the 900-2700 orientation measured 249". Welding distortion was noted as the cause. Laser measurements of the assembled dryer were conducted and confirmed that QC2 dryer base was approximately 2 inches out of round.

Note: Subsequent sections of this RCA refer to this as the "ovality" issue.

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4/25/05 GE Deviation Disposition Request (DDR) 431002828-27 (Ref. 7) was approved, accepting the dimensions of the base plate as-is. Investigation determined the dimensional deficiencies resulted from welding performed at J. T. Cullen, which resulted in distortion of the dryer mid-support ring, skirt and base plate. The DDR noted that the dryer will fit in the vessel despite this ovality. Normal clearances were "compromised" so additional guidance constraints were placed in the lower guide block to limit misalignment and assist in installation.

Notes: 1. The additional constraints noted above are the guide rod spacer blocks installed under Field Disposition Instruction (FDI) 0085 (Ref. 9)

2. This DDR addressed the dimensional issues due to the ovality but did not address potential residual stresses in the dryer as a result of this distortion.

4/26/05 The U-2 replacement dryer was transported to the station and subsequently moved to the reactor building refuieling floor.

4/26/05 Exelon Nuclear Fuels determined that the replacement dryer dP will be less than the original dryer (original dryer dP was nominally 0.3 psid versus an expected dP of 0,1 psid on the replacement dryer).

This change has an impact on Minimum Critical Power Ratio Operating Limit, and on the ASME overpressure results. Root cause analysis on these issues is assigned under IR 330331 (Ref. 37).

Note: The subsequent RCA concluded: "the root cause of the event was a lack of information on the project team regarding the sensitivity of non-structural analyses to the dryer dP value.

5/4/05 The Configuration Change Review Checklist (CC-AA-102 Attachment 10F) for the dryer modification EC351168 Revision 1 was signed by the Reactor Services department representative.

Note: This was a second user's review in the Exelon design process. This review is considered a "cross discipline" review and a barrier to prevent negative impacts of design changes. This topic is discussed further in the evaluation section. This review was documented after the dryer was already fabricated and staged on the Quad Cities Refueling floor.

05/07/05 Unit 2 shutdown for Q2P03 for the main purpose of installing the replacement dryer.

511/105 During initial installation in the U-2 reactor vessel an interference was encountered that prevented setting the dryer onto RPV dryer support lugs. At approximately 2.5" above the dryer support lugs, the overhead crane cables went slack and the dryer assembly shifted towards North (approximately 1100 azimuth). The dryer was lifted and the vessel area inspected without identifying the source of the interference. Upon restart of the descent, the dryer again stopped and shifted towards North.

The dryer was raised slightly to allow further detailed inspection. A camera inspection inside the skirt revealed that the inner diameter of the dryer skirt base plate was interfering with the steam separator Page 7 of 43

guide rods. Although the overall outer diameter of the dryer assembly was not changed by the new design (Ref. 1), the skirt inner diameter is smaller with the base plate protruding farther towards the center of the dryer than the original design. This resulted in the interference with the separator guide rods, with the skirt base plate contacting the two guide rods located at the 200 and 200° azimuths.

Installation activities were stopped and the Outage Control Center (OCC) was notified of the issue, and discussions were initiated to determine resolution of this problem.

Note: The U-2 replacement dryer exhibited limited clearance between the RPV dryer support lugs and the cutouts provided in the base plate ring. As the dryer is lowered, the skirt base plate must pass all four of the support lugs. The width of a support lug is 3 inches, while the width of the base plate cutout provided is 4-inches, leaving a nominal "1/2"clearance on each side of the lug. This presented a known challenge and plans were to use additional care: to field verify that acceptable clearance existed, or modify the clearances as needed. While the dryer was lowered into the RPV for the first time, the GE Product Line Manager was stationed in the reactor cavity to monitor the clearances. It was confirmed during this initial lowering that the clearance between the base ring cutout and RPV lugs was small, but the dryer had been installed without incident until the interference with the separator guide rods was identified.

5/12/05 When the interference between the separator support rods and the base plate was identified and the dryer could not be installed, it was decided that the dryer would be removed from the RPV to allow modification of the base plate. The OCC recovery and action plan for the dryer removal discussed the tight clearance issue with the oncoming crew. Instructions were provided to the oncoming refuel floor crew performing the dryer lift to watch the RPV lug clearance very closely due to the tight clearance.

During the lift for removal of the dryer, the base plate impacted the vessel support lugs despite the increased scrutiny, including performing the lift slowly, as evidenced by multiple stops. Att. 7 describes in detail the sequence for the base plate contact with the RPV support lugs. At the time of this dryer lift, the load cell display for the overhead crane was not functional (overload cutout circuits were functional), so there was no ability to estimate the impact load based on floor observations. Workers reported visual evidence of a high load on the lift cables from the noise and rapid cable movement when the load sprung free. When the dryer was set on the decontamination pad, visual damage to the base plate was evident and the OCC was notified.

Inspection of the base plate showed a downward deflection/distortion in the dryer base plate from its normal flat horizontal shape. These downward bends were recorded as 3/4" at the 1400 location, 5/8" at the 220* location, and 5/16" at the 320* location (Ref. 1).

A detailed discussion of what occurred during this "Lift Event", along with pictures of the damage are provided in Aft. 7.

5[13/05 Prompt Investigation Report 334348 (Ref.4) on the dryer damage was performed and presented to MRC on 5/13/05. This report reviewed the sequence of events, and detailed the observed damage as follows:

1. Marks on the bottom of the base plate at the 20* position

2. Mark (burr) on the inside of the base plate at the 220* position

3. At the 400 and 1400 positions, seismic shim blocks were noted to have shifted and were scratched

4. Raised metal on 3 clearance slots Page 8 of 43

5. Wear on one RPV support lug Items 1 through 3 were believed to have occurred when the dryer shifted towards North as it contacted the separator guide rod. The prompt investigation described conflicts or problems with:

1. Original tolerances did not allow the separator guide pins to clear the ID of the dryer base plate.

2. Traveler Package KCZKU-INSTALL-1 stated that special care should be taken to verify no interferences exist, as well as the need to maintain the dryer level and to watch the overhead crane load cell for deviations

3. The overhead crane load cell was not functioning.

This prompt investigation concluded that the base plate damage was caused by interference with the separator guide rods and RPV support lugs.

Note: The prompt investigation addressed the fact that the dryer could not set into place due to contact with the separator guide rods. It noted that the cause of the damage was not known at this time (this was handed off to the subsequent ACE). The prompt did not discuss the effects of the damage to the dryer from the lifting event.

5/15/05 To eliminate the interference between the separator guide rods and the skirt/base plate, cutouts were provided in the dryer skirt and the base plate at the 200 and 2000 azimuth locations. (W0732708-01 / GE Field Deviation Disposition Request (FDDR) RMCN06243, Ref. 29). The cutout of the partial penetration weld was seal welded at the cutout and examined via PT exam.

The damage to the base plate was evaluated and found acceptable by GE, an independent third party review, and Exelon for use-as-is (Ref. 1 & 8). FDDR RMCN 06245 included instructions for the material cleanup and disposition of the as-left deformations. The indications caused by the contact with the RPV lugs during the dryer removal were removed from the metal surfaces of the dryer and examined via PT exam prior to reinstalling the dryer in the reactor vessel.

Note: This RCA reviewed this FDDR, and the supporting documentation, and noted a lack of detail in documenting both the inspection and analysis activities completed to resolve this issue.

Because this RCA concluded that the transientimposed on the base plate and dryer skirt was a causalfactorfor the subsequent cracks during operation, it must be concluded that the Q2P03 review (May 2005) was a missed opportunity to determine the actual state of the dryer. This topic is discussedin more detailin the Evaluationsection.

5/16/05 Unit 2 was started up and operated at EPU and pre-EPU power levels during the remainder of the fuel cycle. No apparent complications to Unit 2 operation due to steam dryer issues were observed during this oper4ting cycle, and the dryer cracking condition was not evident until reactor disassembly for

• Q2RI 8 in March 2006.

5/25/05 An ACE (Ref. 2) for the steam dryer lifting event was completed and approved on this date. This RCA reviewed this ACE in detail following the identification of cracking in Q2R18. The results of this review are discussed in the Evaluation section.

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This ACE also noted the fact that the crane load cell was not working at the time of the May 2005 dryer lifting event, concluding that that this was not a significant factor in the apparent cause. (Note: The load cell was repaired May 16, 2005 prior to placing the dryer back into the vessel (WO 805641-02)).

A GE Root Cause Analysis (Ref. 6) was provided on 5/25/05. This report determined that the cause of the' interference between the base plate and the steam separator guide pins was that the dryer design process did not ensure'that fit-up problems did not exist. This occurred because the Computer Aided Design (CAD) model was not adequately developed. The GE RCA noted that several GE design engineers had initially identified the potential for interference at the separator guide pins, but had failed to revisit the concern prior to completion of the dryer design.

3/28/06 U-2 shutdown for refueling outage Q2R18. While performing IVVI during Q2R18, the cracks were discovered on the steam dryer that led to the initiation of this RCA. The scope of this RCA includes (references noted are for the original Exelon Corrective Action Process (CAP) Issue Report (IR) numbers, and the GE Indication Notification Report (INR) numbers):

Event 1- The large crack in the dryer skirt at the 1400 azimuth (Ref. 10, 11)

Event 2- Dryer "E" bank end plate crack at 3200 azimuth. (Ref. 12, 13)

Event 3- Latch Box crack at 2200 azimuth. (Ref 14, 15)

In addition, all four steam dryer lifting eyes were discovered out-of-position, with one lifting eye exhibiting thread damage to the lifting rod. This issue was originally in the scope of this RCA, but it was determined that the lifting eye concerns were not related to the dryer cracking issues. For this reason, the lifting eye issue was removed from the RCA scope, and transferred for evaluation as a separate Equipment Apparent Cause Evaluation (EACE) (AR# 471848-05). A summary of the results of this EACE appears below:

Summary EACE 471848-05: Dryer Lifting Lug Rotation Apparent cause: The design of the lifting eye retention method was inadequate to ensure positive engagement. The design provided no ability for ensuring adequate alignment. The recess was located on the lifting rod, which was contained within the threaded connection once the lifting eye was threaded on. The design relied entirely on external orientation of the lifting eyes, which provided no positive verification. In addition, the dimensions of the recess provided minimal opportunity for successful engagement.

Corrective Actions:

1. Modify/Install design of Quad Cities Unit 2 Steam Dryer Lifting Eyes to provide more robust anti-rotation. (Completed before start-up from Q2R18)

2. Modify/Install design of Quad Cities Unit I Steam Dryer Lifting Eyes per EC 360571.

(Scheduled for completion during Q1M19 in spring 2006).

3. Similar corrective actions will be completed on the Dresden replacement dryers prior to installation.

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Identification of Missed Opportunities:

This RCA used the information presented in this event description (and the associated Event and Causal Factors chart in Att. 1) to identify potential issues and missed opportunities for earlier detection, or prevention of the three events in the scope of the RCA. These items are listed below and became the subject of more detailed analysis described in the next section.

Missed Opportunities for Earlier Detection or Prevention of Dryer Cracking:

1. Inadeguate inspection of the May 2005 damage: Actions were identified in Ref. 1 & 8 to perform a liquid penetrant test (PT) of adjacent welds. The Field Deviation Disposition Request [FDDR]

(Ref. 8) was not clear in identifying specific welds to be inspected - it just specified, "all adjacent welds in the areas that were distorted shall be subjected to PT examination". Interviews with QC personnel determined that only adjacent welds on the outside diameter (OD) of the skirt were PT examined. The weld between the vertical skirt plate and the horizontal base plate on the ID of the skirt was not examined either visually or via PT. This was a missed opportunity to determine the integrity of the base material and weld integrity on the skirt inside diameter (ID) and thus we cannot conclusively eliminate the skirt ID as a crack initiation site. The lack of inspection of the ID of the skirt also eliminated the potential to find the "dimpled" section of the skirt at the 140 and 2200 locations which may have led to further analysis of the residual stress placed on the metal.

2. Inadequate disposition of May 2005 damage: In the original dryer design effort, the lower skirt hardware was included in the modeling as a "super element". That is, because the as-designed load conditions on the dryer skirt are typically low and the size of the finite element model was already excessively large, the skirt details below the water line were not included in the finite element calculations with fine nodal granularity. The entire lower area is modeled as a lumped mass and stiffness matrices in the finite element calculations. This is appropriate if the service conditions stay inside the assumed "as-designed" bounds. However, once this portion of the unit had been subject to permanent, localized damage, a rigorous evaluation would have considered whether the dryer was subject to future degradation. This was not specifically included in the disposition of the damaged area.

3. Deficiencies in Design Change Development: A fundamental change in the design of the dryer caused the outer diameter of the dryer shell skirt plate to be reduced, in order that the drain channels could be on the exterior of the dryer assembly. (Note that the outer diameter of the horizontal skirt base plate was the same. The vertical skirt shell plate was reduced.) Exterior drain channels were used in an effort to reduce minor cracking commonly experienced in the area of internal drain channels in earlier designed BWR steam dryers. In addition, because the more robust replacement dryers were heavier, the designers looked for non-structural areas where weight could be reduced. For these reasons, the original design use of 2 continuous guide channels for both of the dryer guide rods, and (4) guide channels for the RPV support lugs were eliminated. These channels were each changed from being a continuous vertical guide path along the height of the dryer skirt, to being two-point (top and bottom) alignment connections (Dryer guide slots for alignment with the RPV guide rods), and Base Ring cutouts to pass through the RPV support lugs. The original guide channels for the RPV support lugs had the same 4" wide clearance as the new dryer's base plate notches. The implication of this is that the tight tolerance on the rotational alignment is enforced at all axial positions during movement. It is this enforcement of rotational alignment that was compromised by the removal of the guide Page 11 of 43

channels. The 4" wide notches in the base plate only "enforce" this alignment while the base plate is at the elevation of the RPV lugs, setting up the potential for misalignment at other dryer elevations. This, in conjunction with the small clearance (the RPV lugs are 3" wide, so the average clearance is 1/2/2" on each side) increase the probability that an impact would occur, by making a higher demand on the users to obtain the simultaneous alignment without impact. Thus a negative consequence of the revised dryer design sacrificed a tolerant and self-correcting configuration for a less tolerant configuration that invited interferences.

4. Fabrication "Ovality" Issues: Fabrication deficiencies had already been identified prior to the May 2005 lift event. These deficiencies resulted during the welding of the two halves of the QC2 dryer at J. T. Cullen. This assembly process resulted in distortion of the dryer mid-support ring, skirt and base plate.

The distorted as-built dryer base plate condition was identified, evaluated and addressed prior to shipping the dryer to Quad Cities under a Deviation Disposition Request (DDR) (Ref. 7).

Corrective measures were taken to prevent this distortion in the assembly of the subsequent dryer assemblies (QC I dryer). The distorted QC2 dryer was evaluated and accepted for use, with actions to install additional guidance constraints on the lower guide blocks. (Refs.7&9), This evaluation focused on vessel clearances for installation and removal of the dryer but did not address potential for induced stresses on the dryer components resulting from the distortion.

Despite the completion of these corrective actions to accommodate installation and removal of the distorted QC2 dryer, the assembly distortion still contributed to the excessive clearances between the dryer and dryer guide rods, and was cited as one of the two apparent causes in the ACE for the May 2005 events. These conditions indicate two missed opportunities:

• The potential for installation alignment issues was recognized after the "ovality" was identified but corrective actions were not successful in preventing the lift event.

" The potential for internal metal stresses induced from the "ovality" was not formally addressed in the DDR, FDDR, EACE, or EC's reviewed during this RCA.

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IV. Analysis:

Several root cause analysis techniques were used in this investigation. Initially, an Event and Causal Factor Chart (Att. 1) was created to document the known sequence of events, and conditions. This document was used to identify an initial strategy and direction, including the decision to divide the concerns into three issues (Dryer Skirt Crack, Dryer End Plate Crack, and Lifting Lug Concerns). The investigation team then used Failure Modes and Effects Analysis (FMEA) to identify potential failure modes. These potential failure modes were documented on a Complex Troubleshooting Failure Mode Tree (FMT) (ref. MA-AA-716-004, Att.2 pages 3 and 4). Each failure mode was then broken down into potential causes with associated validation and action steps. These actions were then prioritized according to the probability of the failure mode being a causal factor and the availability of data (some validation steps were able to be completed early in the investigation while others required additional time for analysis). The FMT's for Event I and Event 2 appear in this report as attachments 5& 6 respectively.

The Lifting Lug Concerns were later determined to be a separate issue from the Dryer Cracking and transferred from the scope of this RCA to EACE AR# 471848-05. For this reason the FMT related to the lifting lug issues is not included as an attachment to this RCA. Similarly, as the Q2R1 8 dryer inspections continued, and additional issues were identified, the Latch Box Cracking near the 2200 azimuth was added to the RCA scope as Event 3 based on a potential linkage to the other two issues. A new FMT was not created for this event because it was evident that the analysis and strategy used for Event 1 (Skirt Crack) and Event 2 (End Vane Bank Crack) were appropriate and bounding for Event 3 (Latch Box Crack).

The FMT charts identified a set of low probability and higher probability failure modes.

The lower probability items were set aside allowing a focus on the higher probability items which included:

" Design related issues where the analysis used might have underestimated the loads the replacement dyers would be subject to, and also underestimated the stress conditions resulting from the skirt base cutouts.

" Design related issues that effected the resulting "lift event".

• Fabrication errors, which resulted in the skirt base ring ovality.

• Installation damage resulting from the "lift event".

These probable TapRoot, Causefailures modes were reviewed using additional RCA tools such as:

and Effect Analysis, and Barrier Analysis. The RCA also utilized a significant amount of technical analysis including metallurgical testing of samples of the U-2 Dryer skirt and baseplate, and computerized structural analysis. This analysis is described in more detail below:

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A. Structural Analysis Summary:

Detailed finite element models of the dryer skirt and other dryer components were developed or upgraded. Multiple elastic and inelastic finite element analyses were run to simulate the conditions that would have caused the observed deformations. These simulations were used as sensitivity evaluations such that some postulated loadings could be eliminated (i.e., if the loads and stresses resulting from some scenarios couldn't have caused the observed deformation, the scenario could be eliminated). Some of these analyses were used to approximate the material condition resulting from these events and to assess the extent of the possible degradation.

1. The original full steam dryer finite element model contained a super element for the submerged portion of the skirt and water. The skirt in the super element did not have the detail of the base plate cutouts or gussets located on either side of the cutout. A local solid 3D detailed finite element model was created for analysis of the failure location.

The analysis validated that the cut out modeling was not significant in determining the skirt stresses & modal response. (Ref. 29)

2. More detailed elastic-plastic analysis of the skirt cutout and gusset areas at 1400 was completed. This analysis predicted 17.3% strain at the top of the gusset in the skirt panel.

Strain at the edge of the gusset in the cut out was 4%, which corresponds to 55-60 ksi using elastic-plastic analysis. (Ref. 21) This analysis also estimated the amount of loading needed to cause the observed deformation from the list event to be 47,000 pounds.

3. An analysis was completed to estimate the corresponding reduction in the fatigue stress limits in the 140" azimuth Dryer Skirt Crack as a result of the lifting event.

Excerpts from this analysis report (Ref.40) appears below:

"...given the higher plastic strain and complementary increase in strength of the deformed base ring location, the expected fatigue endurance properties would be significantly reduced due to mean stress effects. This effect can be calculated directly from the equations used by Manjoine, et al [Ref. 41 of this RCA].

Although the region of interest was cold worked by the installation event [referred to as the "lifting event" in other sections of this RCA], the evaluation of the mean stress effect was performed based on the fatigue properties of annealed material.

Therefore, the evaluation should be viewed in qualitative rather than quantitative terms. For conservatism, the loading was considered as stress controlled in the determination of the mean stress effect, i.e. the range of P1 + Pb +Q was assumed to exceed 27.2 ksi. The impact of an assumed residual (mean) stress of 60 ksi would be a 30% reduction in the allowable while the assumption of a 70 ksi yield strength to represent the local mean stress would reduce the allowable by 50%.

These levels of reduction in fatigue properties are very likely given the deformation and the constraint imposed by the several intersecting welds present at the base ring cut out corner-solid gusset-skirt region where crack initiation occurred."

"In summary, the plastic deformation would be expected to lead to a high residual mean stress. Consistent with the understanding of fatigue behavior in the presence Page 14 of 43

of high mean stresses, the fatigue endurance limit would be reduced. Based on the conservative evaluation, the reduction in endurance limit would be expected to be a maximum of 50%."

3. Hydrodynamic and acoustic loading on the dryer were re-evaluated. Ref. 21 noted that the turbulent water loads acting on the dryer skirt were not analytically evaluated, but the skirt is in a relatively quiet region near the vessel wall. This indicates that any loading on the skirt from the feedwater flow and separator flow will be a turbulent buffeting from the mixing of these flow streams below the skirt. Since the replacement dryer skirt design should be more able to resist these turbulent loads (replacement dryers used 3/8" thick vs.

1/4" thick plate and the drain channel design/fabrication moved the weld away from the discontinuity), it can be concluded that the water loading on the replacement dryer skirt would not present any fatigue issues.

The July 2005 report on "QC U-2 Replacement Steam Dryer Stress and Fatigue Analysis Based on Measured EPU Conditions (Ref. 35) was reviewed and it was noted that there are additional hydrodynamic loads, assessed to be too low to be of consequence. An acoustic load frequency at 155 Hz appears on the strain gauges and accelerometers and based on the magnitude of the response in power spectral densities is the most dominant mode in the reactor. This mode has been attributed to the Electromatic relief valve (ERV) stub tube resonance and is included in the load basis for the analysis.

Further modal analysis concludes that the failed skirt does not have modes in the low frequency range. This means that while the loads may be impacting the dryer, they are not driving structural resonances. In addition, these frequencies would affect the entire dryer, not just the skirt panel. This results in a conclusion that these loads are not a causal factor in this RCA.

4. A detailed stress analysis of the dryer lifting event was completed (Ref. 36). The analysis report concluded: "In this analysis the lifting forces were applied unevenly in various configurations on the full dryer finite element model in order to assess if the lifting event could have caused crack initiation in the vane bank end plates and/or latch box. The results indicate that no lifting cases could initiate a crack in either the inner vane bank end plates or latch box comer."

B. Follow-up Inspections Summary

1. The inside of the dryer skirt at the 200 azimuth where previous damage from impact with the separator guide rods had been noted were re-inspected and evaluated. This evaluation concluded that the damage was small with no deformation of the base ring.

While the minor damaged was repaired, the conclusion remains that impact in this area was not a causal factor in any of the cracking events in the scope of this RCA.

2. The inside diameter of the dryer skirt ring was re-inspected and evaluated at the 1400, 2200 and 3200 areas. The 140 0 area already required repair of the identified skirt and base ring cracking. The 2200 area had a similar amount of base ring and skirt plate deformation as the 140" area, but no observable cracking. The similar deformation was Page 15of43

the major factor in the decision to cut out and replace the deformed material at the 2200 area despite no observable cracking (Refs. 27 & 32). The 3200 area had gusset deformation less than half that at the 1400 location, and no ID skirt or base ring deformation so this area was analyzed to leave "as is".

C. Metallurgical Analysis Summary:

Cut out samples of the cracked areas of the dryer skirt were sent out to GE's metallurgical labs at Vallecitos, CA. The purpose for the testing was to determine the following:

.1. Site of crack initiation

2. Mode of crack propagation

3. Material characteristics germane to the investigation

4. Likely cause of cracking The results of these examinations were documented in "GE-NE-0000-0052-9666, QC U-2 Replacement Steam Dryer Metallurgical Evaluation" (Ref. 19). In addition GE completed a separate evaluation of the Transgranular Stress Corrosion Cracking (TGSCC) identified in these metallurgical samples in the report listed as reference 16 to this RCR.

Excerpts of the Executive Summary and selected sections from the metallurgical report is report are reproduced below:

Executive Summary of GE Metallurgical Evaluation (Ref. 19):

During inspection of the replacement steam dryer at Quad Cities Unit 2 during Q2R18, cracking was observed in the skirt and base plate at the 140 degree location. Samples were removed from the dryer and sent to GE's Vallecitos Nuclear Center for further evaluation.

Visual examination of the samples showed a relatively smooth straight fracture in the skirt plate, consistent with a fatigue mechanism. Examination of the sample taken from the base plate to skirt plate weld confirmed the fatigue cracking mode.

No evidence of ductile tearing (i.e., overload) was found. Near the inner diameter (ID) of the base plate, the fracture exhibited slight twisting, which suggests there was a torsional component to the loading by the time the crack progressed to the ID. The cracking appeared to have initiated in the base plate region and progressed upward into the skirt plate. Although no clear initiation site could be identified, the fracture most likely initiated near the OD of the base plate.

Optical metallographic examination of the skirt plate-to-base plate weld cross sections showed two key features: (1) the root areas of the ID and OD welds contained lack of penetration; and (2) transgranular, branched cracking characteristic of transgranular stress corrosion cracking (TGSCC) initiated from the root area and propagated into the skirt and base plate in both the 140 and 220 degree sections. Neither feature, however, could be identified as an initiator of the Page 16 of 43

observed fatigue cracking. Some increase in hardness was noted in the skirt plate, consistent with the observed deformation. The material chemistries were consistent with austenitic stainless steels.

Based on the observations, the material failed by mechanical fatigue, initiated towards the OD of the base plate region. Given the deformation observed in the samples examined, the stresses introduced into the cut-out region by bending and the location of the cracking, it is likely that the lifting event contributed to the observed failure.

Excepts from Discussion Section of GE Metallurgical Evaluation (Ref. 19):

Subsequent SEM (Scanning Electron Microscopy) examination of the fracture surface confirmed the transgranular nature of the cracking, consistent with fatigue. All regions that were examined were consistent with a fatigue cracking mechanism, with no evidence of ductile overload found. Some lack of penetration was noted in the weld root, which is consistent with the partial penetration weld geometry specified for the skirt to base plate weld. Inclusions in the weld root were also identified; based on the EDS [Energy Dispersive Spectroscopy]

analysis, these inclusions most likely resulted from the original welding process, and were not associated with the failure.

Optical metallography confirmed that the welds were fabricated with at least two passes, which is consistent with the partial penetration weld geometry specified for the skirt to base plate weld. In addition, lack of penetration in the weld root was observed in all of the six cross sections examined. Optical metallography also confirmed that the material was in a solution annealed condition, with some evidence of strain hardening in the base plate, as determined by microhardness.

The areas of apparent strain hardening are consistent with the deformation from the lifting event. The cracking mode was transgranular with small secondary cracks, consistent with a fatigue mechanism.

One additional observation was the presence of transgranular cracking in the weld root region of both the 140 and 220 0 samples. Given the branched nature, along with the presence of multiple indications in both the skirt and base plate regions, the most likely cause is TGSCC. TGSCC requires three factors to be present:

(1) wetted environment; (2) aggressive species (e.g., halogens); and (3) stress.

Wetted environment: At the 140 degree location, the weld root crevice was exposed to the environment Aggressive species: Given that the partial penetration weld was made by a flux-core process and weld fluxes typically contain fluorides for fluidity and wetting, the presence of fluorine in the weld root is not unexpected. In addition, the manufacturer of the weld flux confirmed that approximately 3% fluorine was present in the welding flux.

Stress: Significant stress would be present from welding. [The deformation from the lifting event was also a source of stress.]

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Since all three factors are present, TGSCC is the most likely cause of the observed transgranular, branched cracking in the weld root. Two factors, however, indicate that TGSCC did not contribute to initiation of the fatigue cracking: (1) On the fracture face, the transgranular cracking was consistent with fatigue. There were some secondary cracks, but no major network of secondary branched cracking that would characterize a TGSCC crack was found, and (2) the initiation region (see Figure 3-3(b) in Ref. 19) does not appear to be in the root of the weld. The directional features indicate initiation on the OD surface. The laboratory examination confirmed that the primary fracture was one of mechanical fatigue; however, the exact initiating location could not be identified.

Key Conclusions from GE Metallurgical Analysis The GE metallurgical analysis proved to be a key component in this RCA. While the exact initiation mechanism of the dryer skirt plate could not be identified, the results did eliminate several of the potential failure mechanisms, and supported a determination of most probable causes. This included the conclusions below:

1. Skirt plate cracking is consistent with fatigue cracking.

2. There is no evidence of ductile tearing.

3. Cracking appears to have initiated in the base plate region and then propagated into the skirt plate.

4. The fracture most likely initiated near the OD of the base plate.

5. TGSCC was observed in samples from both the 1400 and 220* regions, but in neither case was the TGSSC identified as an initiator of the fatigue cracking.

6. Deformed areas exhibited some increase in metal hardness.

7. Material chemistries were consistent with austenitic stainless steel.

D. Interview Summaries:

Interviews were completed with a number of key positions associated with this RCA.

This included personnel from: Exelon Reactor Services, GE Installation, and GE Design personnel. A summary of the information from these interviews appears below:

A. Reactor Services:

1. Use of Crane Load Cell Scoreboard:

e Originally installed as a corrective action from an OPEX event where a Dryer was attempted to be removed with only 3 of 4 hold-downs unlatched.

0 Typical use of the scoreboard is that the weight of the component will be known and significant deviations will indicate a potential hang up of the load.

Page 18 of 43

• If a significant change in expected load displayed occurs the "Technical Director" (TD) would be monitoring the display and would signal an emergency stop.

• For the Dryer installation the TD's were GE Supervisors.

• The Signal person for the load moves was typically a Venture Boilermaker assigned to the GE crew.

Would an available scoreboard have made a difference in this event? Unsure -

The Dryer lifting rigs are all metal components so any increase in load would occur very quickly, likely before a response could be made by a lift crew, even in slow speeds. In other lifts where synthetic lifting slings are used, the response time might be longer. (In this case, there is a potential that a load cell change could be responded to when the dryer metal starts to deform, and possibly before the deformation would become permanent.)

• The load cell display has been unreliable since installation. Several outages included lifts made where the scoreboard was inoperable.

2. Dryer Issues:

What are the "key points" in a Dryer lift (term noted in several IR's associated with this event)? A: Aligning the Dryer guides with the guide rods, and the interface between the RPV lugs and the Dryer support ring are considered key points of this lift now and historically.

• Rx. Services was aware that the full-length guide channels that existed on the old dryer no longer existed on the new dryers.

• Rx. Services had limited formal involvement with the design of the new dryers (i.e., did not participate in the project team).

Rx. Services personnel signed off on the new design because they believed that it could be made to work with some additional care. They also were aware that GE personnel would supervise the initial Dryer insertion and that modifications would be made if needed to support successful installation and removal of the replacement dryers. (Some of the fit up issues would need to be field verified especially during the first installation).

• Initial insertion of the new dryer allowed for a person to be located in the Refueling bulkhead to assist in alignment. This option will not be available in future lifts because they will be done underwater for dose control.

B. GE Personnel:

Dryer Project Installation Personnel

1. What was included in the pre-job brief for this evolution? A: The pre-job brief prior to the initial dryer move focused on the movement from the refuel floor to the vessel, since this was an abnormal move and resulted in various load path issues. It also included discussion of the dryer clearance issues and that the dryer Page 19 of 43

design was different and would require significant monitoring while being installed.

2. What process document covered this lift (procedure, traveler, etc.)? A: The traveler provided the direction for initial installation of the dryer - Rev. 0 for the initial move and Rev. 1 for the final installation following modifications. The removal for modifications was performed per the station reactor disassembly procedure.

3. What were considered "key points" in this lift? Were they formally documented?

A: There were hold points when the dryer base ring was at 6-inches above the RPV lugs and again when the mounting block was 6-inches above the RPV lugs.

4. Why was the inoperable load cell scoreboard considered acceptable? A: It is not unusual for load cell/displays to be malfunctioning at various plants.

Dryer Project Design Personnel

" The Dryer design was changed from full-length channels was to accommodate relocating the drain channels from the inside of the dryer skirt to the outside of the dryer skirt. To be able to fit in the vessel, the skirt diameter was reduced to make room for the drain channels on the outside of the skirt. Full-length guide rod channels previously integral to the skirt could no longer remain.

" The replacement dryer design uses a 4-point contact design which also minimizes weight increase. The new dryers are more structurally robust through the use of heavier material. The increased weight has to be maintained within the structural capabilities of the existing RPV dryer support lugs.

• This installation hardware is consistent with the design of newer GE BWR's.

There has been no experience of a similar "Lift Event" in these newer BWR's.

" The ovality event was noted as a factor in degrading the alignment of this QC U-2 replacement Dryer.

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V. Evaluation:

This evaluation section is organized as follows:

A. Table of all Causal Factors that this RCA concluded influenced this event.

B. Additional discussion of the basis for cause determination.

C. Discussion of other event conditions that were evaluated as potential causal factors, but rejected, how they were eliminated as causal factors, and their final disposition (no action required, addressed in "Programmatic/Organizational Issues, addressed in "Other Issues" section)

The final section C is needed because this RCA required extensive technical and analytical review and in some cases, cause determinations relied on elimination of other causes to support the RCA conclusion of root and contributing causes.

A. Table of Causal Factors Cause (describe the cause and identify Problem Statement whether it is a root cause or contributing Basis for Cause Determination cause)

Event 1: Crack & CFla: Lift Event- Design Note: The basis for cause determination is deformation of factors: similar for CFla, & CF2b and are combined dryer base plate 1) New dryer skirt base ring had below:

and skirt cutouts to fit around RPV support

• Root cause supporting analysis concluded identified in lugs, previous design had full that the skirt region cracking would not Q2R18. length channels, have initiated'had the Q2P03 dryer lift

2) New dryer has two dryer guide event not occurred.

slots at top and bottom of skirt vs: e Lift event resulted from changes in dryer full-length channel in old design. installation hardware, not from personnel Root Cause errors during dryer removal.

Event 1: Crack & CFlb. Lift Event - Fabrication: a Tolerances between the dryer guide rod deformation of Ovality Results in Looser slots & guide rods allows for rotational dryer base plate Installation Clearances - movement of dryer resulting in skirt base and skirt Distortion/ovality of dryer base plate cutouts not aligned with RPV identified in plate further degraded alignment support lugs.

Q2R18. control provided by dryer guide

• Tolerance in guide components was slots. further degraded by ovality issue.

Root Cause See Evaluation of Lifting Event Causal Factors CFIa, CFlb (section after this table) for more details on basis.

Event 1: Crack & CF2: Disposition of damage from

• FDDR accepted condition as-is but did deformation of Q2P03 lift event concluded "use not fully evaluate the material effects of dryer base plate as is". GE FDDR, and site the damage (focus on fit issues).

and skirt review concluded:

idntid skint re Assumed damage occurred in low stress identified inIII page 21 of43

Cause (describe the cause and identify Problem Statement whether it is a root cause or contributing Basis for Cause Determination cause)

Q2Rl8.

• Modify base ring for regions.

separator guide rods

• Inspections limited to visual & PT in the

• Run for 1 cycle outside diameter areas. No detailed

• Repair/modify base ring for inspection of inside diameter.

RPV Lugs in Q2R18

• Since follow-up analysis in this RCA did C not identify an exact initiation mechanism Contributing Cause for the cracking, a more detailed analysis during Q2P03 is unlikely to have changed the outcome. (For this reason, this issue is considered a contributing cause rather than a root cause).

• Retained as a contributing cause because of small possibility that more detailed inspections could have detected cracks in the skirt or base plate, specifically on inner diameter areas.

See "CF2: Disposition of Lifting Event Prior to Start-up from Q2P03" (Second section after this table) for more details on basis.

Event 1: Crack & CF3: Analysis - Operating Cycle Operating pressure oscillation loads from deformation of Impacts MSL acoustics resulted in skirt base ring dryer base plate stresses that when combined with the and skirt reduced fatigue endurance caused by the identified in Contributing Cause plastic deformation from the lift event, Q2R18. was adequate to initiate and propagate cracking.

• Considered a causal factor in crack initiation and propagation but not a root cause because analysis has concluded that the operating loads are not sufficient to initiate cracking on their own.

Att. 4 of this RCA presents a comparison of the U-2 pressure sensor data with the areas that experienced damage, which supports the conclusion that operating cycle impacts were not initiating factors or root causes to this event.

Event 2: Crack CF4 - Cracking in Gusset 19 of

• The basis for the cause determination is found in vane Vane Bank "E" End Plate Near photographic observation by the root bank of"E" bank the 3200 Location - most cause team and GE's evaluation Page 22 of 43

Cause (describe the cause and identify Problem Statement whether it is a root cause or contributing Basis for Cause Determination cause) near 320 ° probably due to assembly, and (Reference 17).

azimuth residual welding stresses, The "Lift Event" was rejected as a causal minimal weld thickness, factor for this event using a detailed stress proximity to a weld-stop (stress analysis (Reference 36) riser) and the presence of operating vibration loads Root Cause Event 3: Latch CF5 - Cracking in the 2200 Latch

• The basis for the cause determination is Box Crack at Box - Per Ref. 18, the most likely the analysis and evaluation discussed in 220* azimuth cause of the cracking is fatigue Reference 18, which concludes that the cracking, the presence of a weld most likely cause of the cracking is the end discontinuity and likely high presence of a weld end discontinuity and weld residual stress at the comer likely high weld residual stress at the location, comer location.

Root Cause

• The "Lift Event" was rejected as a causal factor for this event using a detailed stress analysis (Reference 36)

B. Discussion of the Basis for Cause Determination for Three RCA Events.

Event 1: Crack & deformation of dryer base plate and skirt.

1. CFla, CF1b: - Lifting Event Causal Factors A. Lifting Event: The May 2005 "Lifting Event" where the dryer was damaged from impact of the skirt base ring with the RPV lugs was a causal factor that contributed to the dryer cracks discovered in Q2R18. An apparent cause evaluation (ACE) was completed and approved in May 2005. This RCA reviewed this ACE and determined it to be an appropriate starting point for further analysis to determine why the event occurred.

The ACE (AR 334383) concluded:

"Two apparent causes were identified for this ACE. First, lack of clearance between the Dryer base ring plate and the Separator guide rods resulted in damage to the ring plate and shifting of the Dryer that caused minor damage to two of the seismic support blocks. Second, excessive clearance between the Dryer guide rods and the Dryer (guide slots) allowed the Dryer to move enough that the close tolerance notches in the Dryer skirt base ring plate no longer aligned with the RPV dryer hold-down lugs. This allowed the ring plate to catch on the underside of the lugs and result in deformation of the ring plate in three areas."

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This RCA considers the lack of clearance between the dryer skirt base ring and the separator guide rods to be an initiating event, but not a causal factor because the dryer is designed to be installed and removed as many times as needed to support plant operations. The interference with the separator guide rod was the reason for dryer removal in this case, but not the reason for the lift event. Therefore the next level of "Why" focused on the excessive clearance with the guide rods, and the close tolerances between the skirt base ring notches and the RPV lugs.

This RCA did consider the possibility that the cause of the impact was related to human performance issues with the crew removing the Dryer in Q2P03. This consideration arose from the fact that the U-2 Dryer was installed without damage twice during Q2P03, and removed once during Q2R18. (The Q2R18 removal was under the same configuration and close tolerances as Q2P03 since the modifications to improve this condition had not been completed yet). Information from interviews with personnel involved in the successful moves of the U-2 dryer, support a position that while the dryer can physically be removed under the configuration existing in Q2P03, the tolerances are such that an unacceptable risk of impact exists even with a reasonable measure of care.

This information coupled with the results of the previously approved ACE led to a conclusion that the causal factors of the lift event were more related to the hardware clearance issues than crew human performance. Therefore the RCA pursued a "Cause and Effect Analysis" on the changes to design of the dryer installation hardware which resulted in the increased clearance with the guide rods, and the close tolerances between the skirt base ring notches and the RPV lugs noted in the ACE.

Cause & Effects Analysis - Design Changes to Dryer Installation Hardware (CF1a)

1. What were the changes?

Dryer Guide Device Clearance: The previous dryer had two guide channels that ran the outside length of the dryer. Once the channel was engaged onto the RPV dryer guide rods, little movement occurred as the dryer was installed into the RPV. Similarly, these full-length channels allowed for less movement when the dryer was removed, when compared to the new dryer design that uses dryer guide slots at the top and bottom of the Dryer Skirt. On the replacement steam dryer there are only 4 points of contact between the dryer and guide rods: - two at 0 and 1800 on the base ring, and: -two at 0 and 1800 on the mid-support ring. When the mid-support ring is not engaged with the dryer guide rods (i.e, the support ring is higher than the top of the upper dryer guide rod brackets),

there are only 2 points of contact between the dryer and guide rods, at 0 and 180° on the base plate. Stated another way, only when the dryer base plate is 2" or more below the bottom of the RPV dryer support bracket (vessel lugs) will there be 4 points of contact.

Thus, there are only 2 points of contact between the dryer and guiderods any time the dryer base plate is at the same elevation as the RPV dryer support brackets (vessel lugs).

The dryer is therefore much less constrained in terms of the dryer/guide rod interface in the replacement design than it was in the original design, especially when the dryer base plate is at the same elevation as the RPV dryer support brackets (vessel lugs).

Skirt Base Ring Cutouts for RPV Support Lugs: The previous dryer used a channel mechanism to allow the dryer skirt to pass along the 4 RPV lugs. The new dryer design had cutouts at the skirt base ring that were nominally 4 inches wide to fit around a RPV Page 24 of 43

lug that is 3 inches wide. This allowed a one-inch margin (one half inch on each side) to install the dryer onto the RPV lugs.

2. Why were the changes made?

The new dryer installation project was completed to address past experiences with structural damage to the old dryer during operation at Extended Power Uprate (EPU) conditions. The new dryer was an original equipment manufacturer (OEM) replacement of a more structurally robust designed dryer. The reason the design was changed from full-length channels was to accommodate a change to relocate the drain channels from the inside of the dryer skirt to the outside of the dryer skirt. Since the OD of the dryer had to remain the same diameter so as to be able to fit in the vessel, the skirt diameter was reduced to make room for the drain channels on the outside of the skirt. The full-length guide rod channels that were previously an integral part of the skirt thus could no longer remain integral to the skirt. It was decided to not incorporate the full-length guide rod channels into the replacement dryer design and instead use the 4 points of contact design so as to minimize the weight increase of the replacement dryer. (As the dryer is made more structurally robust, the weight increases as heavier material is used, and the increased weight had to be maintained within the structural capabilities of the RPV dryer support lugs.)

3. Why were the potential adverse consequences to the installation hardware changes missed?

Barrier Analysis: The barriers expected to prevent adverse consequences from this design change included:

a. A design product provided by the vendor designer where all potential adverse consequences associated with the change are addressed.

b. Review and approval of the vendor provided product by Exelon design personnel using the process defined in CC-AA-10, "Configuration Control Process Description" and other associated procedures.

c. Review of the design product by the end user (in this case Reactor Services) to determine if there any adverse installation concerns created by the design change.

In this case the vendor providing the design product is GE, who was also the Original Equipment Manufacturer (OEM), Interviews witha GE design person indicated the use of slots versus channels was considered an acceptable option based on trouble free application of this design in the dryers of more recent vintages of GE BWR's. The GE designer believes that the use of slots in the new dryer was, and is acceptable, but in the case the QC2 dryer, was further degraded by the "ovality" fabrication issue.

Site design personnel review efforts were focused on structural factors, the instrumentation unique to this particular dryer, and similar technical items. The design engineers have little "hands on" experience with dryer installation. The Exelon Engineering Change (EC) review process accounts for this gap in hands on experience by using cross discipline reviews from personnel who do have this experience. In this design change, the end user, Reactor Services completed Att. IOF of CC-AA-102, Page 25 of 43

"Configuration Change Review Checklist for Use by Other Departments" indicating they understood and accepted the impact of this change on their department. Follow-up interviews with GE and Exelon Reactor Services personnel indicated that the change in installation hardware, and resulting closer installation tolerances, was a well-known issue. These personnel believed the change could be accommodated with additional care during installation. One example of this additional care was that during the initial installation, personnel were in the reactor refueling cavity bulkhead to closely watch the lowering load. This option was known to not be available in future Dryer installations since they are performed under water after the dryer has been exposed to operating conditions that elevate the radiological dose rates. The intent was to determine if the dryer could be successfully installed despite these tighter tolerances, and pursue modifications if needed for future installations.

This evaluation concluded that for these changes to the dryer installation hardware:

-OEM (GE) personnel had provided the design for use in the Exelon EC process.

• The design change process had been followed as specified in the governing procedures.

• Appropriate "end user" personnel (in this case Reactor Services) had been included in the design change review.

• These Reactor Services personnel had significant experience.

Despite these factors, unanticipated negative consequences occurred, that were associated with these design changes.

This evaluation pursued the organizational and programmatic factors that had influenced these negative results. At this point in this RCA, it was known that causal factors associated with this event shared some similarities with those of another recently approved RCA, an investigation of Electromatic Relief Valve Solenoid Failures (Ref.

38). A review of the corrective actions associated with the ERV RCA identified that several of these actions would be well positioned to address the weaknesses identified in this RCA.

Additionally, a second RCA "QC2 Replacement Steam Dryer Impact on Fuel Analysis Results" (Ref. 37) was reviewed. This RCA was completed in May 2005 when it was determined that the replacement dryers would not meet the design requirement for differential pressure (dP). This RCA contained corrective actions intended to reduce the probability of negative consequences associated with major design changes and projects.

Corrective actions will be needed to prevent recurrence of the dryer lifting event specific to the RCA (since dryer removal will occur each future refueling cycle). Actions will also be needed to address the organizational and programmatic issues that allowed the negative design change consequences to occur. The subsequent section, "IX. Corrective Actions to Prevent Recurrence", and "X. Corrective Actions", presents corrective actions associated with the lifting event. Section "XII. Programmatic/ Organizational Issues" details the corrective actions to address the more global concern related to preventing unanticipated negative outcomes of design changes.

Page 26 of 43

CF1b: Cause & Effects Analysis - Fabrication Induced Ovality The additional movement and reduced tolerances allowed by new installation hardware in the QC U-2 dryer was further degraded by a fabrication problem which resulted in the skirt being approximately 2 inches out of round ("ovality issue"). The orientation of the out of round position further allowed additional movement between the dryer guide slots and the RPV guide rods. The concern related to the ovality impacting installation clearances was recognized. The DDR (Ref. 7) resolving the ovality issue noted -

"Dimensional analysis of the as-built hardware indicates that the dryer will fit in the vessel. Clearances normally available have been compromised, so additional guidance constraints will be placed in the lower guide block, to limit misalignment and assist in installation." The additional guidance constraints were in fact installed as documented in Ref. 9. These constraints helped reduce potential movement between the dryer and the vessel wall, but did not have any impact on lateral movement. It is believed that this lateral movement contributed to the "lift event" by allowing the dryer to rotate about one inch due to the slop between the dryer guide slots rods and the RPV dryer guide rods.

This minimal rotation contributed to the dryer skirt base cutouts for the RPV lugs, being out of alignment with the RPV lugs, which allowed for the skirt base plate to impact on the bottom of the reactor lugs as the dryer was being lifted'out of the reactor vessel.

Note: Att. 7 contains more detailed descriptions and pictures regarding the movement of and damage to the U-2 Dryer during the Lifting Event.

CF2: Disposition of Lifting Event Prior to Start-up from Q2P03 Given that this RCA concludes that damage from the May 2005 (Q2P03) lifting event was a primary causal factor for the cracking identified during Q2R1 8 inspections, and the damage from this event was a known issue, it is logical to conclude that this disposition was a "missed opportunity" to prevent the dryer skirt cracking. This section describes the evaluation performed for potential causal factors associated with the reviews completed after the lifting event that occurred. The table below describes the major reviews and milestones that occurred, during and shortly after Q2P03.

Q2P03 Lift Event Follow-up Decision Timeline Date Time Event 5111/05 2300 Lift event occurred (approx.)

05/12/05 0156 OCC notified 05/12/05 0700 Prompt Investigation Initiated (Ref. 4) 05/12/05 NA Exelon comment matrix for review of FDDR RMCN 06243 notes need to assess:

1. "cold work and/or residual stress in the weld."

2. "magnitude of the plastic strain to determine the Page 27 of 43

potential susceptibility."

05/13/05 -0700 Liquid Penetrant testing performed on selected (prior to damaged and/or repaired areas of Dryer install) (Ref. 1) 05/13/05 0710 Dryer Repaired, Modified and set into the RPV 05/13/05 0900 Prompt Approved by MRC.

(assumed) 05/13/05 NA FDDR RMCN06245 Issued by GE to Resolve Lift Event Damage. Implemented under Exelon WO 742798-1 (Ref. 8) 05/14/05 NA PORC approval of EC 351168- Rev.2- incorporating FDDR RMCN 06243 into the Exelon EC process.

05/16/05 0345 U-2 Start-Up from Q2P03 05/24/05 NA Exelon Corporation concurrence letter for FDDR RMCN 06243 issued. (Ref. 30) 05/25/05 NA ACE on Lifting Event Approved by MRC (Ref. 2)

This RCA reached the following conclusions regarding the Q2P03 assessments of the lifting event:

1. There was no evidence of any formal review (HU-AA- 1212, or similar process) to specify what areas of the Dryer areas were to be inspected after the lift event.

Non-destructive examination (NDE) personnel performed liquid penetrant examinations of damaged and or repaired areas at the direction of GE refuel floor supervision. (Ref. 1) These examinations included outside diameter areas, no inner diameter areas were inspected.

2. Only anecdotal evidence of evaluation of cold work or elastic strain impacts could be found. Personnel who were involved in the review of the GE FDDR (Ref. 8) recalled discussions of these topics, and conclusions that the ductile nature of stainless steel, and low stresses in the skirt/baseplate regions, made future problems unlikely. This RCA found no documented, formally reviewed structural analysis reports or evaluations completed prior to restart from Q2P03.

Formal structural analyses (Ref. 29&36), and metallurgical evaluations (Ref. 19), were completed as part of thisRCA. Because these analyses could not identify the exact initiation mechanism of cracking, a detailed analysis during Q2P03 is unlikely to have changed the outcome, (formal analysis would have concluded the unit could be restarted without major replacement of dryer skirt components). For this reason, the weaknesses associated with the Q2P03 lifting event disposition are not considered a root cause to this event. The weaknesses are retained as a contributing cause because more detailed Page 28 of 43

inspections could have detected cracks in the skirt or base plate, specifically on the inner diameter areas. In addition, more detailed inspections in the inner diameter regions would have better identified the magnitude of the deformation, which may have resulted in a different conclusion of corrective actions needed.

Event 2: Crack found in vane bank of"E" bank near 320* azimuth The basis for the determination of minimal weld thickness, proximity to a weld-stop (stress riser) is photographic observation by the Quad Cities root cause team. Reference 17, Figure 1, last image, shows that the weld buildup is smaller than adjacent portions of the weld and also shows the weld-stop. Additionally, hood assembly and weld residual stresses may have been produced due to the alignment of 6 vane panels in the "E" hood and the weld shrinkage when welding the hood panels and gussets to the vane panel end plates and trough. (This results from differential thermal expansion and contraction that occur from the temperature difference between the weld bead and the cooler base metal.)

These factors are postulated to, in the presence of operating vibration loads, have initiated the crack.

Event 3: Latch Box Crack at 2200 azimuth The basis for the cause determination is Reference 18, which notes "that the crack appeared to have initiated at the comer where one latch box to skirt panel weld either began or ended. Also, the weld end appears to have a discontinuity in the form of a small crater. It is well known that the beginning or end of a weld bead could have some discontinuities that could serve as a fatigue crack initiation site. The other contributing factor could be the corner location where the two welds are meeting that could produce high fit up stress at that location. The presence of high weld residual stress could lower the fatigue stress threshold and may result in the initiation of a fatigue crack. Therefore, it is concluded that the most likely cause of the cracking is the presence of weld end discontinuity and likely high weld residual stress at corner location."

Page 29 of 43

C. Discussion of Evaluation of "Other Conditions" Conditions in the table below were determined to not be CF's for this event, but warrant additional discussion for clarity purposes, and to ensure priority issues are resolved even if they did not contribute to these events. The table summarizes these events. For some of the more complex issues, a more detailed discussion appears at the end of the table.

Condition Description Issues, Basis, Resolution C.1: Crane load cell unavailable.

• Effect of not having load cell display available was not effectively resolved prior to the lifting evolution.

• RCA inconclusive if load cell could have prevented event but there are clear opportunities to enhance the use of this barrier in future.

• CA's specified in "Other" Section (More detailed discussion appears at the end of this table.)

C.2: Finite Element Model Did

• RCA determined extensive issues in configuration Not Include Detail For New control between the as built replacement dryers and Dryer Design Below Water Line the GE analysis model (one example - base plate cut-outs were not included in analysis model).

• Structural analysis associated with the RCA determined that this lack of configuration control did not contribute significantly to this event (Ref. 29)

(More detailed discussion appears at the end of this table.)

C.3: Metal Stress Inducing

• Base plate and skirt gusset load concentration not Factors - Design: Used super modeled.

element model for new dryer Model assumed full penetration welds for the base design. plate to skirt, while the design and fabrication installed partial penetration welds.

• Analysis model did not include cutouts in the skirt base plate.

• Structural analysis associated with the RCA determined that this lack of detailed analysis did not contribute significantly to this event (Ref. 29)

C.4. Metal Stress Inducing

• Stress induced in the dryer skirt & skirt base plate due Factors - Fabrication: Distortion/ to two halves of dryer being force fit together, ovality of dryer base plate resulting in ovality of the skirt and skirt base plate.

• Stress contribution to skirt cracking would be limited to elastic distortion of the base ring.

• Impact of residual stresses was not specifically Page 30 of 43

Condition Description Issues, Basis, Resolution analyzed in Q2P03 because skirt is a low stress region.

• A follow-up evaluation associated with this RCA (Ref. 33) was completed and concluded that the small plastic strain and residual stresses directly attributable to the ovality issue did not contribute to the observed cracking.

(More detailed discussion appears at the end of this table.)

C.5: Structural - Fabrication: o Dryer material sample showed a lack of weld Welding of base plate to dryer penetration at skirt and base plate connection skirt showed lack of penetration. o Metallugical Analysis completed for this RCA concluded that the lack of penetration was not completely unexpected for this type of weld. This analysis also concluded that this issue was not a causal factor for the observed cracking.

More detailed discussion and excerpts of Ref. 19, the GE Metallurgical Analysis were included in the previous "Analysis" section of this report and are not repeated here.

C.6: Structural - Fabrication:

• Dryer material samples from both the 1400 and 220*

Use of halide containing weld regions indicated a presence of TGSCC.

wire coupled with cracking

. Metallurgical Analysis completed for this RCA allowed SCC initiation, concluded that the TGSCC was not an initiating factor for the observed fatigue cracking. TGSCC in the 1400 region was more extensive than the 220* region. It is believed this condition was caused by the water introduced to the area after the fatigue cracking occurred in the 140" area.

• More detailed discussion and excerpts of Ref. 19, the GE Metallurgical Analysis were included in the previous "Analysis" section of this report and are not

• repeated here.

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C.1: Crane Load Cell Display Unavailable Allowing Excess Forces On Dryer The Reactor Building Overhead Crane (RBOC) is provided with a load cell that will sense the weight on the crane hook with an output signal to a crane power interlock switch. The set point of this switch is 250,000 lbs (125 ton), equal to the rated crane capacity. The load cell signal also provides input to a digital readout, which if properly calibrated, will provide the accurate weight of a lifted load. There is a primary readout on the control unit located on the crane trolley, which cannot be viewed remotely. There is, however, a secondary display that can be viewed from the crane operator's cab as well as the refueling floor.

During the review of the Steam Dryer lift event on May 12, 2005 (Q2P03) it was determined that this lift was performed with a non-functioning digital readout display from the load cell (secondary display). (Note: The 125-ton crane power interlock was functional, only the display function was inoperable). Procedure QCMM 5800-05 "Reactor Building Overhead Crane Utilization", Step 3.3.1 states:

"if the readout does not display any digits, WRITE a Work Request for repair.

This does not render it inoperable if all view angles around the lift can be verified to ensure no interferences are encountered."

There is no evidence that a Work Request (WR) or an Issue Report (IR) was initiated at this time, however, a prior request was initiated on 4/21/05 (AR# 327007). This request (WR# 176082) was closed to WO# 805641-02 for calibration of the load cell and repair of the digital readout, which was completed on 5/16/05, approximately 4 days after the dryer lift event.

Per discussion with the contracted crane maintenance vendor, it is understood that the digital readout will provide accurate indication of a slight change in load (= 200 lbs) on the crane hook, which would be indicative of a load hang-up. It is also understood that monitoring of the load could easily be accomplished by using a dedicated person to watch the display for any increase in load indication. This person would be located near the signalman, thereby being within sight of the crane operator without distracting either the signalman or the crane operator from their respective load handling responsibilities. The person monitoring the load display can terminate the lift at any time a change in load is observed.

Based on the speed of the hoist in slow speed (< 2ft/min.) and reasonable reaction times by the load monitor and the operator, it is expected that the lift could be suspended with a minimal amount of load on the contact points due to hang-up of the load.

The ACE conducted at the time of the event (Ref. 2) concluded that since the rigging is a "metal to metal" contact throughout, any load cell deviations would be instantaneous and would not allow for operator action to prevent possible consequences ... " This RCA, however concludes that had the load cell secondary readout been functioning and a dedicated person assigned to monitor and halt operation of the crane at a predefined criteria the damage could have been minimized.

The finite element analysis conducted to estimate the force necessary to permanently deform the skirt base ring 3/ of an inch would be around 47,000 lbs. Since the load cell can sense load differences as small as 200 lbs., and the the skirt base plate would deflect Page 32 of 43

in an elastic manner at some lesser force before it would plastically deform to the %inch deflection, the lift could have been stopped prior to any permanent deflection.

During interviews, it was evident that the lack of a functioning load cell display had become an expected norm and the procedure had been written to allow the use of the RBOC without the load cell functional. It is also reasonable to conclude that with the heightened sensitivity to the-dryer clearances due to the changes in design and to fabrication problems (ovality), that more emphasis should have been placed on the operation of the load cell.

C.2 Finite Element Model Did Not Include Adequate Detail For New Dryer Design A potential failure mode that was identified and subsequently rejected, was that the finite element model for the dryer could be inadequate for the new dryer design. If this allowed an inadequate margin condition to exist without the model showing the problem, then a design inadequacy would go undetected.

The evidence indicates that the cracks occurred primarily because of residual stresses associated with the dryer lift / impact event. Normally, the dryer modeling would not be used to ensure margin to mis-handling events, except possibly in very low dimensional clearance margin conditions such as this (where a user error is likely).

During RCA, several vulnerabilities were discovered, which the dryer modelwas not detailed enough to detect. One example is that the gussets placed adjacent to the notches in the base plate, could cause ring deflection(s) to be transferred to the skirt panels, allowing a cyclic loading. A second example was that the cutouts for the RPV lugs were not modeled. This prevented the opportunity to detect local stress conditions that may be present in the skirt or base ring in the vicinity of the cutout. Since the model did not detail these conditions, additional detailed finite element modeling was needed to better evaluate this possible cause.

Additional detailed finite element analysis (FEA) completed in a GE report titled "Quad Cities Unit 2 Replacement Steam Dryer Analysis, Detailed Stress Analysis of Skirt Base Plate Cutouts and Gussets." (Ref. 29) concluded that:

"The analysis results show that the effect of the cutout on the skirt response is insignificant and the original stress analysis without this detail is adequate. In addition, the fatigue stress levels at the cutout in the base ring for all configurations (original, as found, and repair design) are very low compared with the endurance limit of 13.6 ksi ..

"The inelastic analysis results show that the lug/base plate impact resulted in significant levels of irreversible plastic deformation that could have contributed to crack initiation due to a combination of residual stress inherent in plastically deformed structures and flow-induced vibratory stresses."

The conclusions of this analysis supports elimination of lack of detail in the FEA as a potential cause, and supports the RCA position that stresses from the lifting event were causal factors in Event 1.

Page 33 of 43

C.4. Metal Stress Inducing Factors - Distortion/ovality of dryer base plate (Ref 33)

GE completed additional analysis of this condition in support of this RCA. Excerpts of this analysis appear below, which support a position that stresses from ring ovality did not contribute to the events in this RCA:

Given the sequence of events' it is reasonable to conclude, as stated in the DDR disposition, that the distortion of the base ring was a consequence of welding the additional supports into the upper steam dryer structure. Weld shrinkage between the dryer banks could have transmitted a load into the skirt tending to make the structure, including the base ring, slightly oval. However, when considering the potential effects of this distortion relative to the failure observed at the 1400 location, there are two important points. First, it should be recognized that, at 247 inches diameter and only one inch thick, the base ring is a relatively flexible component. Two inches deviation in a 247 inch diameter is only about 0.8%

diametral distortion, which represents neither significant working of the material nor residual stress. In fact, a large fraction of this projected maximum distortion of 0.8% is elastic rather than plastic deformation. Circumferential strain, which would be more indicative of permanent plastic deformation, is essentially a net of zero since the diameter is approximately the same amount undersize 90 degrees from the oversize points. In any event BWRVIP-84* allows up to 2.5%

permanent plastic strain for the purposes of straightening stainless steel components. The plastic strain attributable to the diametral distortion is much less than this limit.

The second consideration is that the failure occurred at the 1400 azimuth, which is approximately midway between the minimum and maximum diameters.

Therefore, the failure occurred near a neutral point where the diametral distortion and stress would be minimal. However, it is recognized that in this region, especially in the cutout in the base ring, the balance between the oversize diameter and the undersize diameter would tend to produce some amount of bending of the ring. This produced some incremental amount of torsional load in the cutout region that would be additive to the overall stress applied in the failure location. Nevertheless, it is concluded the small plastic strain and residual stress directly attributable to the observed diametral deviation had no role in the failure.

Page 34 of 43

VI. Extent of Condition:

Cause being addressed Extent of Condition Review CFla - Guide Channels The Quad Cities Unit 1 and Dresden Units 2 and 3 replacement steam Not Used in New Dryer dryers also do not use channels. The modification to the Quad Cities Design Unit 2 (QC2) dryer of wider base ring slots has been incorporated into the design of these three dryers and the attention required during lift to the possibility of "hanging up" the dryer base ring on the dryer (RPV) support lugs has been communicated to Dresden, and will be communicated to the industry through the OPEX process.

CFIb - Ovality Results in The Quad Cities Unit 1 and Dresden Units 2 and 3 replacement steam Looser Installation dryers were/are constructed in two halves, shipped and welded Clearances together at J. T. Cullen. Measurements showed that the dryer skirt was oval following the welding. The looseness caused by the ovality is postulated to be an element in the dryer removal event. The lessons learned regarding rigging and welding to prevent the dryer from becoming oval have been incorporated in the fabrication of these three dryers.

CF2: Analysis & The evaluations, examinations and analyses performed immediately Inspections of Damage after the dryer lift event in Q2P03 did not have sufficient rigor. As from Q2P03 lift event noted in the Evaluation section, it is likely that these weaknesses, concluded "use as is". GE especially in the analysis area, would not have changed the outcome FDDR, and site review of the event, however there is some finite possibility of a missed concluded: opportunity to prevent this event from this CF. The Programmatic/

Organizational issues associated with this CF are unlikely to be

" Modify base ring for repeated in dryer components, given the limited population of similar separator guide rods dryers, but there are extent of condition concerns related to other RCA

" Run for 1 cycle reports reviewed as part of this analysis. Several corrective actions

" Repair/modify base recently initiated in these other RCA are well aligned with this CF, ring for RPV Lugs in and should be expected to have a positive impact on this concern.

Q2R18 These items will be addressed in more detail in the subsequent Corrective Actions section of this report.

CF3 - Data Collection Vibrations are present to a degree in all the Units. They are measured From Instrumented Dryer and used in the analyses or compared to analyzed levels.

Acoustic Loading @ 150 Consequently this should not be an issue for other stations / units.

Hz CF4 - Issue 2: Bank "E" Section 1 of Reference 19 reads in part: "Following the discovery of End Plate Cracking cracking <in Gusset 19>, all remaining locations were inspected. All of the other gussets were found to be acceptable with no evidence of cracking." Therefore, it is concluded that this is an isolated incident.

CF5 - Issue 3: Steam Latch box protectors have been installed under EC 351167, Rev. 1 for Dryer Latch Box Cracking Unit 1 and EC 348286, Rev. 0 for Unit 2. No other latch boxes were found cracked during these installations.

Page 35 of43

VII. Risk Assessment:

Plant-specific risk Basis for Determination consequence Industrial Safety - Although the load cell display was not functioning, the circuitry does not Minimal Risk allow a lift of over 125 tons nominal. Given the safety factor of 5 required for the crane and other lifting members, the members would have been able to withstand the load up to the crane lift cutout without failing.

Nuclear Safety - Dryer component cracking could result in lost parts. Various lost parts Minimal Risk analyses have been performed in the past (most recently for a steam dryer 94 lb. lifting lug for Unit 1 and a steam dryer 9" x 6" plate for Unit 2). The most significant consequence has been determined to be a risk to production. No risks to nuclear safety have been found. Additionally, the Quad Cities Risk Management Expert and the Corporate Model Owner have reviewed the Steam Dryer Gusset Cracking Condition (JR 473034), the Steam Dryer Skirt Cracking Condition (IR 472321) and GE-NE-0000-0052-6385-RO, Lost Parts Analysis for Dryer Lifting Lug andDryer Skirt Panel Unit 1, to provide support for the PRA modeling. Basically, the risk assessment review found the risk increase associated with these conditions to be minimal and not risk significant, as documented in Reference 26.

Regulatory Impact There is Regulatory Impact from the standpoint that the Station has assured

- Minimal Risk the Regulator that a more robust dryer has been installed, that the loading on the dryer is understood, the dryer has been shown analytically to be able to withstand the loading and that there should be no cracking of the dryer.

However, dryer cracking was found during Q2R18, resulting in a decrease in the credibility of the Station with the Regulator. Note that the dryers are non-safety related, seismically designed. Due to the location of the cracking and the measure strain hardening of the dryer material, the cause of the cracking is judged to be the lift event. Inspection of the Unit 1 dryer during Q1M19 determined that this undamaged dryer did not have cracking comparable to the Unit 2 dryer supporting the conclusion that the dryers were designed adequate to withstand the loads (minus a lifting event) as committed to the Regulators.

Production / Cost - Based on the following, there is minimal likelihood of recurrence of this dryer Minimal Risk cracking event:

a. GE's root cause analysis of the dryer 1400 skirt cracking, Reference 21, identifies the lift event and consequent material strain hardening as the probable cause,

b. Dryer analysis using measured vibration loads and confirmed using strain gages shows that the dryer is able to withstand the operating loadings and

c. The Unit 1 dryer (without a lift event) as-found condition following approximately 10 months of operation, about 1/2/that time at EPU power levels, was acceptable and as expected.

Page 36 of 43

VIH. Previous Events:

Previous Events Previous Event Review None Many OPEX reports were found that identified cracking and most of them identified flow induced vibration or undersized welds as the cause. No case was found of dryer damage due to or during lifting of the dryer.

IX. Corrective Actions to Prevent Recurrence (CAPRs):

Root Cause Being Addressed Corrective Action to Prevent Recurrence Rot aseBinPAdese Owner Due Date Addrssed(CAPR)

CFIa - Guide Channels CAPR 1 - Modifications to improve Completed Completed Not Used in New Dryer installation hardware on U-2 Dryer during Q2R18 Design [i.e., increased lead-in on dryer mounting blocks, install lug spacer blocks, etc.] - EC 348286, Rev. 1 CAPR 2 - Modifications to improve installation hardware on U-1 Dryer

{i.e., enlarging base ring RPV lug Completed Completed cutouts) -EC 351167, Rev. 1 during Q1R18 CFlb - Ovality Results in CAPR 3 - Modifications to improve Completed Completed Looser Installation installation hardware on U-2 Dryer during Q2R18 Clearances [i.e., guide rod block extension] - EC 348286, Rev. 1 CF4- Vane Bank "E" End CAPR 4 - Analysis to justify leave Completed Completed Plate crack, caused by "as is" position (Ref. 17). during Q2R18 little metal between end plates, and proximity to a weld transition (stress riser).

CF5- Latch Box cracking CAPR 5 - Repair to this area. - EC Completed Completed at 2200, causedby high 348286, Rev. I during Q2R18 residual weld stress from weld end discontinuity and comer location.

Page 37 of 43

X. Corrective Actions:

Cause Being Addressed Corrective Action (CA) or Action Item (ACIT) Owner Due Date CF2: Analysis & This RCA concluded that recently See ATT. 9 See Att. 9 Inspections of Damage approved corrective actions for a from Q2P03 lift event RCA related to "Quad Cities concluded "use as is". Electromatic Relief Valve Solenoid (Lack of rigor in analysis, Actuator Failures..." (Ref. 38) are limited follow-up well aligned with CF2 for this RCA, inspections.) and are appropriate corrective actions for this RCA. The corrective actions are comprehensive, and will establish revised programmatic controls to ensure additional rigor is applied to situations similar to the Lifting Event.

These corrective actions are provided as ATT. 9 to this RCA.

CF3 - Operating Loads on Unit 2 - Install Acoustic Side Complete Completed Dryers During EPU Branches (ASBs) to reduce vibration during Q2R 18 Conditions levels - EC 359004, Rev. 1 Unit 1 - Install Acoustic Side A8452DEM AT 435858-Branches (ASBs) to reduce vibration 37 due levels - EC 359006, Rev. 1 05/26/2006 XI. Effectiveness Reviews (EFRs):

CAPR / CA being addressed Effectiveness Review Action Owner Due Date CAPR I & 3 - Remove and re-install the U-2 Rx. services. Q2RI9 Modifications to improve replacement dryer during Q2RI 9. May 2008 installation hardware on U-2 Verify that available clearances are Dryer [i.e., increased lead-in acceptable to prevent damage during on dryer mounting blocks, future dryer installation and removal install lug spacer blocks, activities. The U-2 dryer was modified etc.] - EC 348286, Rev. 1 with improved installation hardware in Q2R18. The U-2 Dryer is slightly different from U-1 due to the "ovality" issue. This action will validate the effectiveness of CAPR I & 3.

AT 472321 - XX (est. after RCA approval)

Page 38 of 43

CAPR 2 - Modifications to Remove and re-install the U-1 Rx. services Completed in improve installation replacement dryer during Q IM 19. The Q1M19: No dryer iremoval or hardware on U-I Dryer U-I dryer was previously modified installation

{i.e., enlarging base ring with improved installation hardware in problems RPV lug cutouts) - EC May 2005. This action will validate 351167, Rev. 1 effectiveness of CAPR 2 by demonstrating that the dryer can be removed and installed without damage.

Validates major RCA Inspection of the U-1 replacement Programs Completed conclusions regarding cause dryer during QIM19 concluded: Engineering Q1M19:

Confirmed no of 3 cracking events in the 1) U-I does not exhibit the skirt- similar damage to U-2 Dryer. (CF's la & lb- cracking present on U-2 during Q2R18 U- 39yer for Event 1, CF4 for Event which supports the position of this (Ref. 39) 2, CF5 for Event 3) RCA that the U-2 lifting event was the cause for the skirt cracking.

2) No evidence Vane Bank or Latch Box cracking which supports position that Events 1 & 2 of this RCA do not represent generic. design weaknesses or operating cycle concerns for the replacement dryers.

CAPR 4 - Analysis to Future inspections in Vane Bank "E" A8451NESPR During justify leaving Vane Bank area during next U-2 outage to verify Q2R19 "E" cracking "as is" (Ref. condition remains acceptable to leave [5/31/2008]

17). as is.

AT 472321 - xx (est after RCA approval)

CAPR 5 - Repair to Latch Future inspections in Latch Box area A8451NESPR During Box cracking at 220* - EC during next U-2 outage to verify repair Q2R19 348286, Rev. 1 completed in Q2R18 was successful in [5/31/20081 preventing future cracking.

AT 472321 - xx (est. after RCA approval)

XII. Programmatic/Organizational Issues:

This RCA identified two programmatic/organizational issues:

A. The original disposition of the lifting event in Q2P03 (May 2005) lacked rigor, and was potentially a missed opportunity to prevent the dryer skirt cracking.

B. Multiple examples of unanticipated negative consequences from the replacement dryer design.

Page 39 of 43

Item A, the original disposition of the lifting event, has been extensively discussed in previous sections of this RCA since it is considered a contributing cause to these events (CF2). As such, there is no need for additional clarifying discussion in this section. Item B, related to unanticipated negative consequences of the replacement dryer design change, will be discussed in more detail to provide specific examples and to clarify the impacts of this issue.

Both issues are included in the table at the end of this section, which summarizes the issue and associated corrective actions.

Unanticipated Negative Design Consequences:

This RCA noted several examples of negative consequences from the design of the replacement dryer. This includes:

1I. Separator guide rod interference with the dryer skirt ring. This issue resulted when the replacement dryer design did not ensure that fit-up problems did not exist. This issue became an initiating factor for the lifting event.

2. The change in dryer installation hardware from full-length guide channels to guide slots and base ring cutouts was a causal factor (CFla) for the lifting event.

This issue resulted when the potential negative consequences of the design change were not identified despite completing the requirements of the design change process, and associated cross disciple reviews.

3. The initial response to the ovality issue included a modification to install guide rod spacer blocks (Ref. 9) to address clearance concerns. This initial modification was completed prior to dryer installation, but was insufficient to prevent the ovality problem from becoming a causal factor (CFlb) for the lifting event.

4. The replacement dryer differential pressure (dP) did not match the design specified value. This issue was the subject of a separate RCA - Ref. 37. The unexpectedly low dP of the replacement dryer dP had negative impacts of- a)

Increased complexity and costs associated with fuel analysis for subsequent operating cycles, and b) Degraded moisture carryover performance from the'new dryers.

• Thenumber of unanticipated negative consequences from the replacement dryer design clearly demonstrate a programmatic and organizational weakness. The consequences of these items clearly warrant corrective action.

As notedin the "Evaluation" section, the issue of unanticipated negative design consequences identified in this RCA shared some similarities with two other RCA's:

e Electromatic Relief Valve Solenoid Failures (Ref. 38).

• QC2 Replacement Steam Dryer Impact on Fuel Analysis Results" (Ref. 37)

A review of the corrective actions associated with these RCA's identified that several of the items in progress would be well positioned to address the issue identified in this RCA.

Page 40 of 43

Attachment 9, section B., lists these corrective actions already tracked by AT's under Refs. 37 & 38.

In September of 2005 a Common Cause Analysis (CCA) was completed on modifications (AR 317566) which identified a need to improve the effectiveness of inter-departmental reviews associated with the design change process. Corrective actions associated with the CCA were implemented in fall 2005, so they would not have impacted the events of this RCA, which occurred in May 2005. A follow-up action is recommended to perform an effectiveness review of the CCA corrective action implementation to determine if they have been successful in improving the use of the inter-departmental reviews in identifying and avoiding unanticipated negative consequences of design changes.

Section B of the table below summarizes the intent of the actions in progress from the other RCA's and lists the actions to be tracked under this RCA.

Programmatic and Organizational Corrective Action (CA) or Action Item (ACM Owner Due Date Weaknesses Item A: Review & Disposition As noted in the previous Corrective See ATT. 9 See ATT. 9 of Lifting Event Damage Actions section, this CF will be During Q2P03 addressed by recently approved corrective actions associated with the ERV Actuator RCA.

These actions are intended to improve the application of formal decision-making processes under conditions similar to the lift event in this RCA. Formal decision making processes will enhance the level of rigor. These actions are listed in Att.

9, Section A of this RCA.

Page 41 of 43

• -Programmatic and Organizational

• Prgr cands OCorrective Action. (CA) or Action Item (ACIT) Owner Due Date Weaknesses Item B: Unanticipated Similar issues identified and tracked under See ATT. 9 See ATE 9 Negative Design other RCA's (Refs. 37 & 38) are listed in Att.;9. These CA's are expected to improve Consequences the effectiveness of inter-departmental reviews of design changes, and to improve the coordination of major modifications that become Exelon projects. New CA's specific to this RCA are listed below.

1. Quad Cities to implement Rev. I of HU-AA-1212, "Technical Task Risk/ Rigor A8400PM -

Assessment..." which includes guidance on QDCDW 07/31/06 how to select what type of third-party AT 472321 review(s) are required. XX (ACIT)

2. Design Eng. to complete an effectiveness review (EFR) of the corrective actions A8452 11/17/06 (CA's) implemented from CCA 317566. NESDP The overall intent of this EFR is to determine AT 472321 if the CA's have improved the use of the inter-departmental reviews in identifying -xx (ACt0 (irt. after RCA and avoiding unanticipated negative approval) consequences of design changes.

(An example directly from this RCA would be: More detailed Reactor Services review

& challenge to ensure the design is usable for dryer installation activities.)

XII. Other Issues:

Other Issues identified during Corrective Action (CA) or Action Item DueDate investigation (ACIT) Owner

1. Crane load cell unavailable a. Evaluate methods to improve Rx. Services 11/10/06 during Lifting Event the use of the load cell as a method of early detection of load AT 4723211 -

"hang up". This needs to include xx (ACrr) establishing expected load values, (est. after RCA and abort criteria when pre- approval) established thresholds are reached. These methods should be incorporated in to QCMM 1 5800-05, or other suitable' Page 42 of 43

• Other Issues identified during Corrective Action (CA) or Action Item Owner Due Date investigation (ACIT) documents. These methods should also discuss appropriate contingencies if the load cell is unavailable, and suitable management review and approval levels for invoking these contingencies. Results of this evaluation should be presented to MRC for closure.

2. Crane load cell unavailable b. Evaluate historical reliability Plant 09/29/06 during Lifting Event of RB Overhead Crane Load cell Engineering.

display. Determine if actions for AT 472321 -

improving future reliability are XX (ACIT) (est.

after RCA warranted. Present results of this approval) evaluation to PHC for closure.

XIV, Communications Plan: Preliminary NER and OPEX information has already been provided for communication within Exelon and the Nuclear Industry. Final communication actions are being tracked by the AT items below:

Lessons Learned to be Communicated Communication Plan Action Owner Due Date Provide NER to share lessons 472321-09 A8430T? 06/01/06 learned within Exelon Provide an OPEX to share lessons learned with the rest of 472321-10 A8401OPEX 06/08/06 the-industry Page 43 of 43

Lifting Eye (1 of 4)

Lifting Rod (1 of 4)

Mounting Block for Latch Assembly (1 of 4)

Dryer Guide Slots Skirt Base Ring Cut-Out for RPV Lug (1 of 4)

Fi-gure 1: Steam Dryer

5/16" Bend RPV Lug Cutout (4 Locations) 2700 .. 900 3/4" Bend Impact on RPV Dryer Support Lug Figure 2 Steam Dryer Plan - Impact Locations

Installation - Dryer is Lowered Into QC2 Reactor Vessel WO 00732708-01 5/ 1/2005 A Large Amount of Welding Laser measurement of assembled is Required to be Performed dryer determines base plate is Guides on the dryer support ring to Assemble the Dryer Parts approx. 2 inches out of round impact the RPV Dryer Support Lugs 4/4/2005 on the way down & bend the spacer blocks.

GE Used Super-Element to Weld 11DE Records Lost for Model Skirt Below Water 300 welds- Consequently, Line- Detail of Lower Skirt Needed to use Reduced Weld Area Not Developed Capacity for Analysis Dryer base ring hits steam separator guide rods. Dryer can not be lowered any further.

Planned Full Penetration Weld Revised to Partial Penetration Plus Fillet Weld On Both Sides of Skirt Plate DDR 431002828-027 (Ref. 7) Dispositions the Nonconfonmance "UJ-As-ls with Additional Guidance Constraints Added to the Lower Guide Block.

Cut Out For RV Dryer Support Lug Judged Acceptable Based On Low Stress in Model ATT. 1:472321-02 Root Cause Report Effect and Casual Factor (E&CF) Chart Att. Page I

While removing dryer from vessel, the dryer base ring hangs up on the vessel drver sum). Ines. ACE, GE FDDR, and analysis concluded to:

" Modify base ring for separator guide rods

" Run for I cycle

• Repair/nodify base ring

~ forRPVLugsinQ2RIS Most probable cause is having very little weld metal between the End Plates, proximity to a Weld Transition (Stress Riser)

When the dryer became stuck, and the Presence ofOperating the crane was required to' Vibration Loads place a force onto the dryer that caused an audible noise. 4/2006: Metallurgical Evaluation results ofBoat Samples show the crack was due to I-igh Cycle Fatigue and comer location.

Metallurgical Evaluation of Skirt to Base Plate Joint Identified Transgranular

- Cracking ATT. 1: 472321-02 Root Cause Report Effect and Casual Factor (E&CF) Chart Att. Page 2

- Event Timeline:

DATE EVENT/ ACTION SOURCE COMMENTS

__DOCUMENT(S)

Prior to Upper and lower halves of e NR - common None 3/2005 dryer are fabricated at U.S. information.

Tool and Die in Pittsburgh, PA 3/2005 Upper and lower halves of

• NR - common None dryer are welded together information at J. T. Cullen, Fulton, IL 4/4/2005 Washington Group begins

• Integrated Steam None laser measurements of Dryer Project J.T.

Assembled Dryer at J. T. Cullen Cullen Fabrication Facility Daily

_Activity Sheet 4/14/2005 QC2 Dryer Base plate is

• DDR 431002828- Disposition provided 4/25/2005, approximately 2 inches out 027 states, *Clearances normally of round.

• EC 351168 available have been compromised, so additional guidance constraints will be placed on the lower guide block to limit misalignment and assist in installation.'

5/4/2005 GE issues FDI to install

• FDI 0085 Modification of replacement steam new guide rod spacer dryer to install "additional guidance blocks and gusset supports. constraints" 5/11/2005 Lower Dryer into Vessel

• WO 00732708-01 5/111/2005 Guides on the dryer support e WO 00732708-01 ring impacted the RPV e AR 334383 Dryer Support Lugs on the e FDDR RMCN way down & bent the 06252 spacer blocks 5/11/2005 Hit Steam Separator Guide aWO 00732708-01 Apparent Cause per ACE:

Rod with Dryer Base Ring - a AR 334348 Dryer could not be lowered 6 FDDR RMCN 1. Lack of clearance between dryer any further 06243 base ring and separator guide

• Separator Guide rods due to wider skirt base ring Rod Interference plate (same OD, smaller ID).

Root Cause 2. Excessive clearance between Summary (Report dryer guide rods and the dryer.

Number AIIOI 39)

• Apparent Cause

• Root Cause Investigation (AR Evaluation (ACE) 00330331-03) was supposed 334348 to address Steam Dryer design (but did not).

• Poor Design was only cause Corrective Action per ACE:

• Modify dryer per EC 348286

_____ _____________________ (see 26A6787_Rev._2_3/7/06) 5/12/2005 Decision made to remove . WO 00732708-01 dryer from vessel I ATT. Page 3

DATE EVENT/ ACTION SOURCE COMMENTS

_DOCUMENT(S) 5/12/2005 While removing dryer from a WO 00732708-01 Apparent Cause Evaluation (ACE) vessel the dryer base ring e AR 334383 Performed under AR 334348 hung up on the vessel dryer e FDDR RMCN support lugs - "Lift Event" 06245 a Prompt Inv.

Report 5/13/2005 Reinstallation of dryer into e WO 00732708-01 vessel.

5/16/2005 Repair of the Reactor a WO 00805641-02 Building Overhead Crane Load Cell 5/16/2005 Operated at EPU and Pre-Q2C18 EPU power levels NR - common information 3/28/2006 U-2 Steam Dryer Lifting e WO 00794824-01 Op. Eval. scope included IR's:

Lugs Rotated

• AR 471848

- INR Q2R18-IVVI- 471848 /472321 /473034 /473344 06-01 e Operability Eval.

1. EC 360272 3/28/2006 Removal of dryer from e WO 00794824-01 vessel.

3/29/2006 U-2 Steam Dryer Lower

• WO 00794824-01 Root Cause Investigation Requested Skirt Cracked @ 1400

• AR 472321

• INR Q2R18-IVVI- "Event 1" 06-02 3/30/2006 U-2 Indications Identified on 9 WO 00794824-01 'Event 2" Steam Dryer Gusset

• AR 473034 e INR Q2R18-IWI-06-04 4/05/2006 U-2 Steam Crack at 2200 e WO 00794824-01 'Event 3" Latch Box a AR 475369 e INR Q2R18-IWI-06-29 ATT. Page 4

Attachment 3 - References Ref. Document Title / Description

1. Reference Number

.1 WO 00732708-01 Replace Unit-2 Steam Dryer Per EC 351168

___EC 351168

• 2 AR 334383 May 2005, ACE on Q2P03 Dryer Lifting Event 3 FDDR RMCN GE disposition of steam dryer interferences between the vessel 06252 - steam dryer support lug and the lug spacer block.

4 AR 334348 May 2005 Prompt Investigation of Q2P03 Dryer-Lifting Event 5 FDDR RMCN GE disposition of Steam Separator Guide Rod Interference 06243 with the Base Ring of the Steam Dryer Skirt.

6 GE Report Number GE Root Cause Summary: Separator Guide Rod Interference AI0139 7 DDR 431002828- GE Disposition of "Ovality" Issue: Steam Dryer Final 027 Dimension Approximately 2 Inches Out of Round.

8 FDDR RMCN GE disposition of May 2205, Q2P03 Lift Event 06245 9 FDI 0085, Rev. 0 Engineering requirements and instructions for the and Rev. 1 modifications of the replacement steam dryer to be installed at QC Unit 2 prior to the Q2P03 dryer replacement outage.

(Modified Jack Bolts, Installed Guide Rod Spacer Blocks, and Gusset Supports.)

10 AR 472321 Q2R18 Identified Crack In The U2 Steam Dryer Skirt.

("Event P"of this RCA.)

11 INR Q2R18-IVVI- Steam Dryer Skirt @ 135 Degrees 06-02 (Note: Most Later References Specify 140')

12 AR 473034 Q2R18 IVVI - Indications on Steam Dryer Gusset (E-Bank

_ End Plate Crack). ("Event 2" of this RCA.)

13 INR Q2R18-IVVI- Steam Dryer Bank E ID 06-04 -

14 AR 475369 Q2R18 Identified 220 Degree Latch BoxCrack

("Event 3" of this RCA) 15 INR Q2R18-IVVI- 220'Degree Latch Box Crack 06-29 " '

16 GENE 0000-0053- GE Review of Transgranular Stress Corrosion Cracking in 1962 Skirt to Base Weld Root Area 17 GE-NE-0000-0052- GE Evaluation of the Bank E Drying Vane End Plate Crack 9728 ("Event 2" of this RCA.)

18 GE-NE-0000-0053-. QC U-2 Replacement Steam Dryer Analysis Evaluation of 0232 Latch Box Cracking and Fatigue Impact of Swing Arm &

Latch Protector Welds ("Event 3" of this RCA) 19 GE-NE-0000-0052- QC U-2 Replacement Steam Dryer Metallurgical Evaluation 1 9666 AUT. Page 5

Ref. Document Title Description

_#_- Reference Number 20 GE-NE-0000-0052- Lost Parts Analysis for Potential Lost Dryer Lifting Eye and 6385-RO Dryer Skirt Panel Quad Cities U-1 GE-NE-0000-0053- Root Cause Analysis for QC2 Steam Dryer 1400 Skirt 21 2926 Cracking ("Event 1" of this RCA) 22 DDR dated Dryer Support Ring 3/8" Out of Flat due to Welding 02/20/2005 Distortion.

23 GE LFW0505-2, Quad Cities U-1 &2 Replacement Dryer Skirt Cutouts:

May 20,2005, DRF (Discusses modifications needed to both U-I and U-2 0000-0034-3781 replacement dryers as a result of Q2P03 Issues.)

24 GE Transmittal No. As-Built Dimensional Analysis, QC-2 Steam Dryer (Report JXD4E-023 dated describing why the U-2 Replacement Dryer will fit in the 4/28/2005 vessel despite the ovality issue) 25 GE-NE-0000-0034- Replacement Steam Dryer Reactor Vessel Bracket Stress 4803-02 Report for Quad Cities 1,2 and Dresden 2,3", April 2005.

RM Documentation Risk Assessment for IR 473034 and IR 472321, Steam Dryer 26 No. SA-1477 Gusset Cracking and Steam Dryer Skirt Cracking, Assignment 03 Root Cause Report.

27 GENE 0000-0052- GE Steam Dryer - Recommendation for Repairs at 220 0 &

8407 & 8408 320* Locations (2 documents - same topic) 28 FDDR Q2R18 Addition of Dryer Guide Rod Block Extensions RMCN08436 29 GE-NE-0000-0053- QC U-2 Replacement Steam Dryer Analysis Detailed Stress 2910 Analysis of Skirt Base Plate Cutout and Gussets, April 2006 30 Exelon-ENG-DRY- Exelon Concurrence with GE Resolution of U-2 Steam Dryer 099CR Collision Damage. Dated May 24, 2005.

31 GENE-0000-0052- Q2R18 Steam Dryer ID Welds Flaw Evaluation, April 2006.

7988 Rev. 2 32 FDDR "Ring and Skirt Assembly", dated 04/05/06. (Specifications RMCN08404 and drawings for repair to 2200 area.)

33 GENE 0000-0053- QC2 Steam Dryer -. Base Ring Diametral Distortion 0605-1 (April 2006 re-assessment of ovality issue) 34 GENE 0000-0053- QC2 Steam Dryer Repair Crevice Assessment (Discussion of 0606 acceptability of skirt plate repairs using backing rings).

35 GENE 0000-0043- QC U-2 Replacement Steam Dryer Stress and Fatigue Analysis 3105-01-P Based on Measured EPU Conditions (July 2005) 36 GE-NE-0000-0053- QC U-2 Replacement Steam Dryer Analysis Detailed Stress 2456-P Analysis of Dryer Lifting (April 2006) 37 AR 330331 RCA: "QC2 Replacement Steam Dryer Impact on Fuel Analysis Results" 38 AR 435858 RCA: "Electromatic Relief Valve Solenoid Actuator Failures

____ ___due to failure to correct the source of the MSL vibrations 39 EC 360876 Review of Q1M19 Critical Steam Dryer Inspection Findings ATT. Page 6

Ref. Document Title / Description

1. Reference Number 40 GENE 0000-0053- Request for Additional Information: QC U-2 Dryer Inspection, 2954, Revision I Start-up & Power Ascension Plan - RAI 9 (b):

Discussion of the corresponding reduction in the fatigue stress limits in the Dryer Skirt Crack.

41 Ref. 3 used in GENE Manjoine, M.J. and Tome, R.E., "Proposed Design Criteria for 0000-0053-2954, High Cycle Fatigue of Austenitic Stainless Steels,"

Rev. 1 - RCA Ref. 40 International Conference on Advances in Life Prediction (above) Methods, ASME, 1983, pp. 51-57.

ATT. Page 7

Comparison of QC 2 Replacement Steam Dryer Pressure Sensor Data with Q2R18 Dryer Damage.

Reason For Evaluation I Scope:

Note: The references in this attachment refer to the items listed on the final page of this attachment, not the RCA Report references listed in Att. 3 Quad Cities Unit 2 (Q2) new steam dryer was installed in May 2005 under EC 351168 (Ref. 1). During installation of the new steam dryer, AR 334348 (Ref. 2) identified that the new steam dryer would not sit in the dryer guides properly. The dryer was repaired and the skirt base plate deflection was documented in GE Traveler (Ref. 3). The skirt base plate deflection at the 1400 AZ location is 3/4",at 2200 AZ location: 5/8", and at 3200 location: 5/16". At the 400 AZ location, no plastic deformation of the skirt base plate was noted. At 1400 AZ, the skirt base plate cutout plastically deformed 3/4" downward with visible inside diameter (ID) deformation and skirt panel with dimple at top of gusset. At 2200 AZ, the skirt base plate was deformed 5/8" downward with visible ID deformation and no evidence of dimpling. At 3200 AZ, the skirt base plate was deformed 5/16" downward with imperceptible plastic ID deformation Q2 steam dryer is instrumented with strain gages, pressure sensors, and accelerometers.

GE Specification 26A6395 (Ref. 4), sheets 15, 16, 17, and 18 provides the sensor locations with respect to the Dryer orientation in the reactor vessel and its relative elevations. During unit start up testing to full power, AR 347867 (Ref. 5) identified that various strain gages and accelerometers were failing. After completion of the testing, Q2 ran at full power for > 200 days before coming down for a planned refueling outage (Q2R18).

Further, inspection of the steam dryer in Q2R18 indicated damage to the dryer skirt (AR 472321) (Ref. 6) and dryer lifting lugs rotated (AR 471848) (Ref. 7). The #7 skirt panel and base plate at cutout cracked after -200 days of EPU operation. At 25 Hz, the skirt base plate and the skirt panel #7 have undergone 4.3e08 cycles Purpose of this evaluation is to a) review Q2 start up test data and compare it with the damage seen on the steam dryer skirt at locations close to the main steam lines (MSL) and b) to see whether the as-builtlas-installed dryer with known damage to the skirt base plate could affect the pressure distribution in the steam space external to the dryer and affect the main steam line frequency patterns at the full load operation of the unit.

Detailed Evaluation:

The new steam dryer orientation was taken from reference 4, sheet 17. Drawing M-3121 (Ref. 8) identifies main steam line nozzle orientation. It should be noted that "A" MS nozzle at 700 is closest to 400 dryer skirt base plate cutout. Similarly, "B" MS nozzle at 1100 is closest to 1400 dryer skirt base plate cutout; "C" MS nozzle at 2500 is closest to 2200 dryer skirt base plate cutout; and "D" MS nozzle at 2900 is closest to 3200 dryer skirt base plate cutout.

ATf. Page 8

Following Table shows the pressure sensors located external to the steam dryer, MSL locations, and other pertinent data. Also,-Document Number AM-2005-012 (Ref. 9) shows actual pressure data taken from Quad Cities Unit 2 start up testing. This pressure data is used in developing the overall evaluation.

• Q2 dryer pressure sensor locations:

0 P3 A hood, opposite "B" MS nozzle.

S P22, P24, & P25 skirt below "B" MS nozzle.

S P12 A hood, opposite A MS nozzle.

S P20 F hood, opposite 'C" MS nozzle.

S P21 F hood, opposite D MS nozzle.

S P15 & P17, hood Closure Plate- B & C hoods.

TABLE No.

1 Main Steam Line (Ref. 8) A A B B C D 2 MSL Azimuth 700 700 110° 1I0° 2200 290u 3 Dryer Skirt Base Plate 400 400 1400 40 2207 3200 Cutout Location -_*

4 Initial Skirt Base Plate None None  % Inch  % Inch 5/8 Inch 5/16 Inch Damage 5 External Pressure Sensors P12 N/A P3 N/A P20 P21 on Dryer 6 External Pressure Sensors N/A P25 N/A P22 N/A N/A on Dryer Skirt above Water Line 7 Min. Pressure, psi -2.069 -1.270 -1.887 -1.379 -1.613 -2.261 (Ref. 9) 8 Max. Pressure, psi 1.907 .1.166 1.817. 1.243 1.588 2.099 (Ref. 9),

9 A Pressure, psi 3.976 2.436 3.704 2.622 3.201 4.360 10 RMS Pressure Measured, 0.69 0.344 0.631 0.422 0.499 0.883

'psi (Ref. 9),

11 ERV(s) on MSL 2-0203-3B & 2-0203-3C 2-0203-3D

_2-0203-3E 12 ARs on ERV None 435838 435838 430555 and

_435838 Conclusions/Recommendations:

a) Review of reference 4 shows pressure sensor locations on the dryer from higher to lower elevation in the following order: P1, P2, P3, P22, and P24. Further review of this reference shows that the pressure sensors P3, P6, P9, P12, P15, and P17 are located 65" below the top of Bank "A". Review of the pressure data from reference 9 for these sensors indicate that pressure reduces when moving downward and when moving away from steam nozzles. Pressure at 1400 location (P3) is lower than pressure at 700 or 2900 ATT. Page 9

locations (PI2 and PP2 1). Skirt pressures are lower than hood pressures as seen from pressure sensor data of P22, P25, P3, and P12. Steam pressure measured at the skirt (P25 and P22) is lower by order of two when compared with the pressures measured at the hood (P12 and P3). Further, the Table shows that steam pressure will be highest for the "D" MSL nozzle, then "A", "B" and the lowest steam pressure will be at "C" MSL nozzle. (i.e., Pressure loads closer to "D" & "A" steam nozzles are greater than the "B" &

"C" steam nozzles).

b) Based on the pressure data, it can be concluded that although the dryer skirt base plate at 3200 AZ has a 5/16" bend and the highest measured pressure (P21 = 4.63 psi), no crack was found. However, at 1400 AZ, the dryer skirt base plate has highest bend (e")and lower measured pressure (P3 = 3.704 psi), yet a large crack in the skirt plate # 7 was noted. Therefore, it can be concluded that pressure oscillations alone could not be the primary cause of the crack initiation and/or propagation.

Further, review of Quad Cities Unit 2 Electromatic Relief Valve (ERV) ARs indicate that ERV 2-0203-3D on "D" MSL has seen more damage than 2-0203-3B and 2-0203-3E on "B" MSL and 2-0203-3C on "C" MSL. However, ERVs on "B" and "C" MSLs also have seen some failures. This evaluation confirms the conclusion reached in Report AM-2005-014 (Ref. 10) which states that "Tables 1 and 2 seem to provide reasonable results in that the normalized flow through Main Steam Lines "A" and "D" are higher than "B" and "C" for both units. This is expected since the "A" and "D" Lines are the shorter Main Steam Lines."

References:

1) EC 351168, Rev. 2: Unit 2 Steam Dryer Replacement.

2) AR 334348: PSU - Steam Dryer would not set all the way down.

3) GE Traveler, Project KCZKU, Traveler No. KCZKU-Base Ring Deflection.

4) GENE Design Specification 26A6395, Rev. 2: Dryer Vibration Instrumentation

5) AR 347867: New steam Dryer Strain Gages/Accelerometers are failing.

6) AR 472321: PSU Q2Rl8 Crack in the U2 Steam Dryer Skirt.

7) AR 471848: PSU Q2R18 U-2 Steam Dryer Lifting Lugs Rotated.

8) QC Drawing M-3121, Rev F: In-service Inspection Isometric Reactor Vessel

9) Document Number: AM-2005-012, Rev 0 An Assessment of the Uncertainty in the Application of the Modified 930 MWe Acoustic Circuit Model Predictions For the Replacement Quad Cities Units 1 and 2 Steam Dryers.

10) Report AM-2005-014, Rev. 0, dated July 20, 2005: Quad Cities Unit 2 New Steam Dryer Outage Startup Test Report.

ATL. Page 10

Att. 5- Event 1: Failure Mode Tree Ref MA-AA-716-004 Att.2 PROBLEM STATEMENT:

ATT. Page 11

Att. 5 - Event 1: Failure Mode Tree Ref MA-AA-716-004 AtL2 Failure Mode No. 1 Description Design Flaw Results Owner

• Expected results aif based on system Status operation as designed. not as failed Cause(s) ValidationlAction Steps Expected Actual RIGOR (A, B, C, D, N/A) D Finite element model error Validate model lAW GE method requirements Model valid 1) Validated GE RCA -

allowed unacceptable stress complete

'A level to be accepted Independent review or model output Review confirms 2) Validated Rich Hall -

complete RIGOR (A, B, C, D, N/A) D Incorrect tolerances to allow for:

1) fit-up 1) Determine the role of Design in the known 1) Impact had 1) Confirmed as RCA - complete B impact of new dryer with RPV lugs, and separator role in crack a CF.

2) heat-up/operational guide pins. Structural analysis and metallurgical initiation.

movement testing to determine if this initiated crack.

2) Review for evidence of rubbing of components 2) No evidence. 2) No evidence. RCA - complete due to expansion or operational forces.

ATT. Pne 12

Att. 5- Event 1: Failure Mode Tree Ref: MA-AA-716-004 Att2 Failure Mode No. ; Description Desigin Flaw Results Owner

• Expected results are based on system Status operation as designed, not as failed Cause(s) ValidationlAction Steps Expected Actual RIGOR (A, B, C, D, N/A) D Inadequate load definition Review of model for design margin preventing No plastic Confirmed GE RCA -

C caused localized high stress plastic deformation deformation complete during design operating predicted conditions RIGOR (A, B, C, D, N/A) D FDDR RMCN 06243 Confirm conclusions of FDDR RMCN 06243 that Material strength Confirmed as GE RCA -

incorrectly allowed use of amount of metal removed still leaves adequate adequate not an initiating complete the machined ring slot with strength per design requirements including event.

strength reduced more than dynamic loads assumed a) How did the load redistribute D b) What material impacts when grinding (GE materials, what impact fatigue life for comp that exceeded 0.2% plastic strain)

Note: Unless metallurgical analysis specifies the presence of IGSSC, grinding and machining are not a CF.

ATT. Page 13

Att. 5- Event 1: Failure Mode Tree Ref: MA-AA-716-004 Att.2 Failure Mode No. 2

Description:

Operating conditions (mechanical) ,_*

Results Owner "Expected results awe based on system Status operation as designed, not as failed Cause(s) ValidationlAction Steps Expected Actual "_ _ _

RIGOR (A, B, C, D, NIA) D A Low quality steam output at Confirm mechanical load from moisture carry- Adequate. No moisture RCA screened as the steam separator causes over is less than the design limit for dryer margin exists carryover low probability.

high moisture momentum components including the cyclic effect of 0.3 Hz concerns load to dryer core power cycles, identified. Closed RIGOR (A, B, C, D, N/A) D Transient event Review cycle history curve for SRV or BPV No blowdown or Review of power RCA screened as ADS/TG blowdown and transients and confirm that transient loads do not transient loads in history did not low probability.

B rapid pressure change or exceed internal load limit and dryer lift limit excess of limits identify any dryer overload transients of concern. Closed Single MSIV closure at Review cycle history curve for asymmetric MSL Steady-state or power causing an flows or higher single MSL flow noise transient asymmetric load asymmetrics insignificant ATT. Page 14

Att. 5- Event 1: Failure Mode Tree Ref MA-AA-716-004 Att.2 Failure Mode No. 2 Description Operating conditions (mechanical)

Refer to Attachment 4 for examples of risk Results Owner and rigor determination for steps below Epeced results are based on system Status operation as designed, not as failed Cause(s) ValidatlonlAction Steps Expected Actual RIGOR (A, B, C, D, N/A) D RCA screened as Cyclic power loads induce Evaluate MSL flow swings causing cyclic loading Fatigue load has Closed low probability high cycle fatigue of total dryer dP to induce fatigue large margin based on factors including CMSL resonance evaluation in Power changes from sitting with RR bistable flow Fatigue load has Att. 8 RR bistable flow power large margin swings cause cycle dryer load Closed RIGOR (A, B, C, D, N/A) D Power/Flow Anomaly Compare core average exit quality (CAEQ) to CAEQ change Closed RCA screened as previous cycles (moisture carryover) from previous low probability.

D High subcooling causes low cycles minimal core exit quality Compare FCL for cycle to previous cycles Closed High Flow Control Line (FCL) causes high core dP ATT. Page 15

Att. 5- Event 1: Failure Mode Tree Ret MA-AA-716-004 Att.2 Failure Mode No. 3 Description Fabrication error or material deficiencies Results Owner

• Expected results are based on system Status operation as designed, not as failed Cause(s) ValidationlAction Steps Expected Actual RIGOR (A, B, C, D, N/A) D

1. GE RCA-Distortionlovality of Cullen 1. Calculate the loads imposed by fil-up with as- 1. No loads Confirmed as not complete fit-up and weld of base to built ovality. (GE to address this in analysis) exceed design a CF A skirt limits.

2. Determine impact of ovality in reducing 2. Ovality impact Confirmed as a 2. RCA team -

clearances and influencing lift event of reduced CF complete clearance is a CF.

RIGOR (A, B, C, D, N/A) D Incorrect or substandard Confirm that materials match the design requests 1. Records 1. Confirmed GE analysis -

materials were used or and that sub component supplier confirm proper complete supplier errors or process certifications/procurement records materials and control failures controls B

2. Metallurgical 2. GE testing analysis indicates that the confirms no materials are material consistent with deficiency. drawings and CMTRs.

Afr. Page 16

AMt. 5- Event 1: Failure Mode Tree Ref MA-AA-716-004 Art.2 Failure Mode No. 3 Description Fabrication error or material deficiencies ____-___*

Results Owner Expecftd results are based on system Status operation as designed, not as failed Cause(s) ValidationlAction Steps Expected Actual RIGOR (A, B, C, D, NIA) _

Incorrect component Confirm dryer fabrication records match No DDR reviews no Summary review fabrication or techniques approved processes discrepancies issues as CFs completed. RCA C identified as problems. screened as low CFs. probability.

Closed RIGOR (A, B, C,) D, NIA) Q Incorrect fabrication Confirm fabrication sequences did not cause No DDR reviews no RCA screened as D sequence interim overstresses such as unsupported spans, discrepancies issues as CFs low probability.

temporary jacking etc. identified as problems.

CFs.

Closed ATT. Pae 17

Att. 5- Event 1: Failure Mode Tree Ref: MA-AA-716-004 Att.2 Failure Mode No. 4 Description Damage during installation Results Owner

• Expected results are based on system Status operation as designed not as failed Cause(s) ValidationlAction Steps Expected Actual RIGOR (A, B, C, Do N/A) D 1&2. GE RCA complete Interference/overload 1. Calculate the loads on the skirt ring, gusset, No overstress No stresses cause excess load skirt panel during lifting determination of 3. Vallecitos A during lift incident overstress, but complete

2. Confirm dryer internal loads with single point lifting event Uneven lift loads "hung up" and weight distributed does not No overstress impacts on Rich Hall (ITPR) concentrate load localized overstress skirt ring during material is most Complete area at 140" location causes installation probable distortion 3. Metallurgical analysis of dryer materials, activities initiating event.

RIGOR (A, B, C, D, N/A) D Rotation/torsion applied Obtain description of "manual rotation" used, Torsion induced Torsion induced RCA screened as during installation caused calculate possible torsion loads loads were loads were low probability.

B localized overstress minimal minimal Closed AUr. Page 18

Att. 5- Event 1: Failure Mode Tree Ref MA-AA-716-004 Att.2 Failure Mode No. 4 Description Damagie durinai installation Results Owner

• Expected results are based on system Status opetatlon as designed, not as failed Cause(s) ValidationlAction Steps Expected Actual RIGOR (A, B, C, D, N/A) D.

Uneven weight distribution Calculate loads/lex caused by sitting on 2 RPV No gusset or Confirmed GE RCA while sitting on 2 RPV lugs: lugs skirt ring complete C caused load concentration overstressed exceeding limits (Note: Considered a lower Priority analysis unless other analysis is inconclusive).

RIGOR (A, B, C, D, N/A) D Load cell Not a CF inoperable is not Site RCA -

RB Crane load cell visual Determine impact of inoperable load cell on lift a CF but complete display not working during event. included in D dryer installation.' "Other" section.

ATT. Page 19

Att. 5- Event 1: Failure Mode Tree Ref: MA-AA-716-004 Att.2 Failure Mode No. 5 Description Operating Conditions (chemistry or flow Results Owner

• Expected results am based on system Status operation as desIgned, not as failed Cause(s) ValidationlAction Steps Expected Actual RIGOR (A, B, C, D, N/A) D Core design issues, power Compare core operating conditions to as named No discrepancy Closed RCA screened as distribution increased local service conditions between design low probability.

A moisture but was damaged and operation by moisture momentum Closed RIGOR (A, B, C, D, N/A) D Steam separator local Inspect steam separator for blocked flow path No blocked Closed RCA screened as blockage caused uneven separator tubes low probability.

B loading (increased flow in part, decreased other)

Closed ATT. PIPý 20

Att. 6- Event 2: Failure Mode Tree Ref. MA-AA-716-004 Att. 2 PROBLEM STATEMENT:

ATr. Page 21

Att. 6- Event 2: Failure Mode Tree Ref MA-AA-716-004 AtL 2 Failure Mode No. 1 Description Fabrication Defect Results Owner

• F.jipeed mults are based on system operation as Status des not as filed Cause(s) Validation/Action Steps Expected Actual RIGOR (A, B, C,D, N/A) D High stress condition or Inspect failed area visually for location or No crack Potential CF: GE RCA -

stress riser created by indication of any crack initiation or defect initiation site or INR Page 2 last Complete inappropriate weld or other defect identified picture shows a A fabrication error location where there is very little weld material and this point appears to be the. initiation site for the crack*

• Based on these inspection results, itcan be concluded that having. very little weld metal between the end plates at gusset 19 contributed to the initiation and propagation of the crack in this location. This incomplete weld combined with hood assembly fit-up and weld shrinkage stresses, and the deformation and loading associated with the interferences during dryer removal are the most probable cause of the crack initiation that would then have been driven to its current size by operating vibration loads.

AT. Page 22

Att. 6- Event 2: Failure Mode Tree Ref: MA-AA-716-004 Att 2 Failure Mode No. 2 Description Inadequate Design Results Owner

• Expected rests are based on system operatonas Status desigued, not as failed Cause(s) Validation/Action Steps Expected Actual Crack occurred in area RIGOR (A, B, C, D, N/A) D Stress is within Confirmed subjected to overstress allowable limits GE RCA A (Finite Element Analysis Stress analysis to identify loading/stresses in area complete.

incorrect)

Failure Mode No. 3

Description:

Material Defect Results Owner

• Expected results are based on system operation as Status designed, not as failed Cause(s) Validation/Action Steps Expected Actual RIGOR (A, B, C, D, N/A) D Defects in plate material Failure not due Closed RCA screened as A created stress riser or highly Inspect plate for evidence of fracture initiation to material low probability.

localized stress location, fretting or fatigue defect Closed AT. Page 23

Att. 6-Event 2: Failure Mode Tree Ref: MA-AA-716-004 Att. 2 Failure Mode No. 4

Description:

Operational Conditions

• Results Owner

• Expected results are based on system operation as Status designed, not as failed Cause(s) Validation/Action Steps, Expected Actual Operating conditions caused RIGOR (A, B, C, D, N/A) D Operating RCA screened as vibrations that exceeded the conditions were Closed low probability.

A design capabilities of the Verify appropriate operating conditions were appropriately vane bank end plate modeled in analysis modeled Closed Failure Mode No. 5 Description Installation/Removal in Overload/Overstress Condition Results Owner

• Expected resrlts are based on system operation as Status designed, not as failed _

Cause(s) Validation/Action Steps Expected Actual Excessive loads were placed RIGOR (A, B, C, D, N/A) D The load was on the vane bank end plates 'within the design Analysis GE RCA A when the Steam Dryer was Determine the load that was applied to the vane limits of the vane concludes this is complete resting on the Steam bank end plate during the incident. bank end plate not a.CF.

Separator Guide Rods Excessive loads were placed RIGOR (A, B, C, D, N/A) D The load was Analysis on the vane bank end plates within the design concluded this is GE RCA B when the Steam Dryer was Determine the load that was applied to the vane limits of the vane not a CF complete stuck on the RPV lugs bank end plate during the incident, bank end plate AT. Page 24

Att 7: Dryer to Dryer Lug Imnact Analysis (Liftina Event)

Background:

During the initial installation of the Quad Cities Unit 2 dryer, the dryer became "hung up" on the dryer lugs. During the initial dryer placement, it was discovered that the dryer base plate interfered with the separator guide rods. As a result, the dryer was removed to allow the base plate to be modified to prevent the interference.

During the lift, the dryer base plate became hung up on the dryer lugs. The interference resulted in damage to the dryer lugs and local yielding of the dryer base plate.

Evaluation: There are four dryer support lugs on the ID of the reactor vessel and four guide slots in the dryer base plate. The guide slots are intended to allow the dryer base plate to move by the dryer support lugs during lowering and lifting. The support lugs and guide slots are located at 400, 1400, 2200, and 3200 azimuths around the ID of the reactor vessel and the OD of the dryer base plate, respectively.

The dryer base plate and the reactor vessel lugs were examined following the incident (Ref. Work Order # 732708-01). The base plate was found deformed (i.e., - bent) downward at the 1400, the 2200, and the 3200 locations. The 400 dryer location was not damaged. The base plate near the 1400 guide slot location was bent down by,% inch, the 2200 was bent down by 5/8 inch, and the 3200 was bent down by 5/16 inch. The base plate near the 1400 was bent on the right hand side, when looking at the dryer, and the other two locations were bent on the left hand side when looking at the dryer. This is shown schematically in Figure 1.

The videotape of the in vessel dryer support lug inspection was reviewed and stills extracted as shown in figures 1 through 12 below. The 400 lug (Figure 3) had a comer deformation on the right hand side of the lug, when looking at the lug from the vessel ID, even though'the dryer base plate at this location was not damaged. The support lug located at 1400 (Figure 4) also had a comer deformation on the right hand side of the lug, when looking at the lug from the vessel ID. The 2200 (Figures 5 and 6) and 3200 (Figures 7 and 8) support lugs were damaged on the lower left hand comer. The worst deformations were on the 2200 and 1400 location.

The design of the base plate cutouts and the dryer guide rod slot would allow the dryer to rotate and potentially allow the cutout gussets to impact the dryer support lugs. Based on the geometry of the vessel lugs and the base plate cutouts, it does not seem reasonable that the dryer would impact two lugs on the right side and the other two on the left side.

This conclusion would lead to the possibility that there were two different impacts, or events. However, based on discussion with individuals who were present, there was only one impact event. That is, the dryer was not lowered or rotated and then lifted again.

This leads to the possibility of multiple impacts during a single event.

The as-built elevation of the top of the dryer support lugs is excerpted from the reactor vessel as-built drawing (CBI drawing 69-4824) and is provided in Table 1.

Attachment page 25

Att 7: Dryer to Dryer Lug Impact Analysis (Lifting Event)

Lug Azimuth Location As-Built Elevation 40 616 - 13/16" 140 617- 1/32" 220 616 - 11/16" 320 616-13/16" Table 1 Dryer Support Lug As-Built Elevation (Measured from the support skirt)

This drawing indicates that the lowest lug is the 2200 lug, and the highest is the 1400 lug.

This assumes that they are all approximately the same length. The data indicates that the 2200 lug is 11/32" (0.344") below the 140 degree lug. Also, the 400 and the 3200 lugs are 7/32" (0.219") below the 1400 lug.

As can be seen in figures 7 through 11, the lugs were also damaged when the dryer was lowered into the reactor vessel. This damage indicates that the combination of dryer support lug as-built location and size combined with the dryer base plate cutout as-built location and size, and the as-built clearances between the dryer guide pins and'guide slots, resulted in a lack of clearance and interference between the dryer support lugs and the cutouts when lowering the load. Since a review of all of the as-built locations and sizes and combinations thereof is difficult and yields results that are subject to the stacking of multiple accuracies, it is sufficient t note that the potential for the interference exists based on the evidence of damage to the lugs from lowering the load.

A plausible sequence of events can be established using the evidence of damage to the dryer support lugs and the dryer base plate and the as-built elevations of the bottom of the dryer support lugs. It cannot be established that this is the exact sequence of events, but only that this is a likely scenario that is coincidental with the established facts.

Since the 2200 dryer support lug is the lowest lug, it is presumed that the dryer base plate cutout contacted this lug first. (Note the contact point for all of the interferences would be the gusset plate that is located on the either side of the base plate cutout.) Also, since

• the dryer contacted the left side of the lug, the dryer is rotated clockwise when looking down from the crane. The initial impact on this lug is supported by the lower elevation and fact that the damage to the dryer support lug at his location was the worst for all of the support lugs (See figures 3 and 4). It is not necessarily supported by the amount of damage to the dryer base plate.

The dryer would continue to be lifted as it yielded both the support lug and the dryer base plate at the 2000 location. Once the dryer had been lifted approximately 1/16", the dryer would contact the 3200 location at the left hand side of the lug. The dryer also should have impacted the 400 lug on the left hand side, however it did not. This can be explained by reviewing figures 7 and 8.

Attachment page 26

Att 7: Dryer to Dryer Lug Impact Analysis (Lifting Event)

Note that the damage to the 40* lug when lowering the load occurred on the right hand side of the lug. This indicates that when the dryer is positioned such that it passes by all of the lugs, it is closer to the right hand side of the 40* lug. Therefore, the largest clearance between the 40* dryer support lug and the dryer base plate cutout would be on the left hand side of the lug. Then, if the dryer is rotated clockwise, it may not impact the left hand side of the 40* lug since that is the side of the greatest clearance.

Once the dryer base plate contacts the 320' support lug, the load is shared between the base plate locations at 220* and 3200. This would help to limit the amount of base plate deformation at the 220* location. The dryer would continue to lift and possibly rotate such that the 2200 to 320* section of the dryer would be lower than the 40* to 140' side.

The dryer released from the 220 and 320* lugs and swung, or tilted, while rotating back counter clockwise. During the tilt or swing, the dryer impacted the support lugs at 40 and 140 degrees. The release mechanism is supported by the edge displacement damage to the 3200 lug, Which makes it appear that the dryer slid laterally away from the lug, causing material on the lug to move downward (Figures 5 and 6). As stated previously, the dryer, once it was free to swing, impacted the lower right edge of both the 40 and 1400 support lugs. The dryer impacted the lower part of the 140 degree support lug and impacted only the edge of the 40 degree lug. The reason the dryer impacted below the 1400 support lug is due to the higher elevation of the lug and the tilting of the dryer. The dryer scraped the lower right hand side of the 40* vessel support lug (Figure 1) because that lug is slightly higher than the 1400 support lug. That is, the dryer did not wedge under the 40* lug because of the lower elevation versus the 1400 lug, but it did hit the edge of the lug, as seen in Figure 1.

Conclusions Based on this evaluation, the following summarizes the interference event that occurred during the initial dryer installation:

1. Dryer base plate guide slots impact multiple dryer support lugs during the initial lowering into position.

2. Dryer base plate interferes with the separator guide pins and cannot be placed in final position. This causes the dryer to be lifted to facilitate modifications.

3. Dryer is rotated clockwise during the lift (slightly, less than 1 inch).

4. Dryer base plate guide slot gusset interferes with dryer support lug at the 2200 location. This results in a '2"high by 3/8" wide damaged area in the dryer support lug and a 5/8 inch downward deflection of the base plate.

5. Dryer base plate guide slot gusset interferes with dryer support lug at the 3200 location. This results in part of the dryer support lug being sheared off and the dryer base plate deflection of 5/16".

6. Dryer tilts noticeably along the 0 and 1800 axis, prior to releasing from the lugs.

7. Dryer releases, swinging back towards 220 and 320* location.

Attachment page 27

Att 7: Dryer to Dryer Lug Impact Analysis (Lifting Event)

8. Dryer rotates and swings into the 140 and 400 lug.

9. Dryer impacts the 140' lug below the right lower edge of the lug.

10. This impact results in a sharp crease in the dryer support lug and the formation of an edge on the base plate gusset. The corner of the 1400 lug is pushed in and partially shears off.

11. During the tilt/rotation, the dryer impacts the right bottom corner of the 400 lug, shearing off the corner.

12. The dryer lift is completed without further incident.

Attachment page 28

Att 7: Dryer to Dryer Lug Impact Analysis (Lifting Event) 5/16" Bend RPV Lug Cutout (4 Locations) 2700° - 900 3/4" Bend

- Impact on RPV Dryer Support Lug Figure 1 Steam Dryer Plan - Impact Locations Attachment page 29

Att 7: Dryer to Dryer Lug Impact Analysis (Lifting Event)

Figure 2 General Relationship Between Dryer Cracking (Top), Dryer Guide Slot Cutout at 140 Degrees (Center), and Dryer Support Lug at 140 Degrees (Bottom)

Attachment page 30

Att 7: Dryer to Dryer Lug Impact Analysis (Lifting Event)

Lower right hand comer indicates scraping damage

~i Figure 3 Damage to 40 Degree Lug, Lower Right Hand Comer Damaged During Impact damage due to impact of dryer 4 J Figure 4 Damage To 140 Degree Lug, Lower Right Hand Comer Damaged Due to Major Impact Attachment page 31

Att 7: Dryer to Dryer Lug Impact Analysis (Lifting Event)

Lower left hand comer damage indicates dryer stuck below support lug Figure 5 Damage To 220 Degree Lug, Lower left hand Corner Same damage as viewed from the bottom of the lug Figure 6-Damage To 220 Degree Lug, Lower left hand Corner (View from Bottom)

Attachment page 32

Art 7: Dryer to Dryer Lug Impact Analysis (Lifting Event)

Damage to lower left hand comer due to dryer. Note.,

some damage indication is from top to bottom.

Figure 7 Damage to 320 Degree Lug, Lower Left Hand Corner SSame Sdamage as previous figure, seen from the bottom of the

~lug.

Figure 8 Damage to 320 Degree Lug, Lower Left Hand Corner (View From Bottom)

Attachment page 33

Att 7: Dryer to Dryer Lug Impact Analysis (Lifting Event)

~ Damage t

~:i..~; ~right hand too low to

~ be caused

~.~..block.

Figure 9 Damage to Right Hand Side of 40 Degree Lug, Due to Base Plate When Lowering Attachment page 34

7 1 - -

Att. 8: Q2RI1 INR Resolution Matrlx*

T 1r I 4-CProposed Resolution IR INR Number Rev Title (Not Finn" Resolution Document EC 471848 Q2R184Wi-06-01 0 Steam Lifing Lugs at45.135.225, &315 Deg Repair Per FDDR RMCN08456 . WO 681384-01, FDDR RMCN08456 Rev B 360356

____ ________~rM-Z 0 ea ryer Skif 2a! I2 Repr 7ýMT MC012 ¶6384-0DR~Q38Rv~,,

474814 Q2R18-iWI-06-03 3 Jet Pump 05 1,D-I) JCO - Possibly replace Q2R1 9 GENE-0000-0052-9152 RO 360359 4_3_3_______1-Ot-Of - et6anv Dyr~SB -V2 S

-2H T-ý Accept 'M, 1§ 475009 Q2R18-iWI-06-05 0 Jet Pump 08 -1) JCO - Possibly replace Q2R1 9 GENE-0000-0052-9152 RO 360359 473344 Q2R18-1WI-06-06 0 Steam Dryer Internal Weld SD-BF-V06-2H-1D Accept As Is wlfuture Inspection I LPA GE-NE-0000-0052-7988-RO 360356 473619 Q2RI8-IVI-06-07 0 Steam Separator Upper Suppor Ring Gusset Accept As Is w/future inspection GENE-0000-0052-8398-RO 360359 473615 Q2R18WVVI-0-08 0 Steam Der Internal Weld SD-BD-V06-2H-ID Accept As Is wluture inspectionl LPA GE-NE-0000-0052-7988-RO 360358 473622 Q2R18-1VVI-06-09 1 Steam Separator Shroud Head Bolt 14 and 35 Rotate and perform VT-3 Video files 481701, 481101, 481301, 481401 360359 473626 Q2R18-1VVI-06-10 0 Steam Dryer Intemal Weld SD-BB-V04-2H-ID Accept As is wlfuture inspection GE-NE-0000-0052-7988-RO 360356 473923 Q2R1 8-WI-06-11 1 Steam Dryer Internal Debris Accept As Is wfuture inspection I LPA Lost Parts Analysis EC 360467 360356 473871 Q2R18.4WI-06-12 0 Steam Dryer Intemal Area (S rator Guide Cutout) Increase clearance FDDR RMCN088242 WO 681384-01, FDDR RMCN08242 Rev A 360356 473839 Q2R18-VVI-06-13 0 Separator Lower SupportRing Gusset Accept As Is w/future inspection GENE-0000-0052-8398-RO 360359 474491 Q2R18-1VVI-0W 14 0 Jet Pump 10 Wedge Assembly Accept As Is w/future inspection GENE-0000-0052-9152 RO 380359 474070 Q2R18-1VV-06-15 0 Jet Pump 07 Wedge Assembly Replace swing gate as planned WO 823272-01 360359 473844 Q2R184IVV.0616 0 FeedwaterSager End Bracket Planned Tack Weld per FDI 0194 GE-NE-0000-0052-8396-RO 360359 474064 Q2R18-iVVI-0W 17 0 Shroud Repair Yoke at 290 Degrees Accept As Is - Installed condition GE-NE-0000-0052-8402-RO 360359 474485 Q2R18-1VVI-0W 18 0 Dryer General Visual (220 to 320 Degrees) NRI - No action required IR 474497 comments 360356 474497 Q2R18-4VVI-0W 19 0 Feedwater Sparger 13&16 Degree End Bracket &Pi, Planned Tack Weld per FDI 0194 GE-NE-0000-0052-8396-RO 360359 474501 Q2R1 8-VVI-06-20 - 0 Steam Doyer Skirt Baseplate at 220 Degrees Repair Per FDDR RMCN08242 WO 681384-01, FDDR RMCN08404 Rev A 360356 475003 Q2R184VVI-06-21 0 Steam Dryer WSL @ 220 Degrees No Action Required - unchanged IR 475003 comments 360356 475328 02R18.lVI-06.22 0 CS Lower Elbow to Shroud Pipe 290 Degree Azimutl Inspect next RFO INR Exelon Level lIIreview 360359 474514 Q2R18-1WI-06-23 0 JSteam orBase Plate Distoton at 320 Degrees No change-Accept As Is EC 360356 360356 474517 Q2R18-1VVIW06-24 0 Steam DrerSurfaceAnomalies at SD-SKT-VI1-ID NRI - No action required IR474517 comments 360356 474977 Q2R18..IVI..6-25 0 Shroud Head Flange Ring Segment (EDM Hole) Accept As Is - Previously evard GENE-771-110-0595 RO 360359 475862 Q2RI8-iVVi-06-26 0 Core Support Flange Ring OD Accept As Is w/uture inspecton GENE-771-110-0595 (May 1995) 360359 475332 Q2R184VVI-06-27 1 0 Shroud Head Flange Ring OD Accept As Is GENE-0000-0053-0964-R1 360359 475339 Q2R18VI-0 8 1 1 Steam Dryer WSLs @ 40,140 and 320 Degrees No Action Required - unchanged IR475339 comments 360356

-475=UffTM 77 9 U- 8 ony - e Indication' eDLB0

,air peTFDOR fRhVCN08435 *04)6815 1DDRC043Rwrw 476654 Q2R18.I WI-06-30 0 RPV Jet Pump Annulus FME Remove FM_E Lost Parts Analysis EC 360467 360359 476657 Q2R18-1VVI-06-31 1 Steam Doer Exit Plenum Perforated Plate Accept As Is GENE-0000-0053-0964-RO 360356 477326 Q2R184VVI06-32 0 -CSSparger $3c Drain (two plugs missing tack welds: Accept As Is GENE-0000-0053-0964-R0 360359 N/A 62R18-1v-06-330 Tie Rod Loose and Missing Nuts (As designed) NRI - No action required INR - Future reference only. Mention in EC. 360359 476540 None - IR only SHB #9 suspect based on UT criteria Accept As Is wfuture Inspection IR,GE Letter DRF B13-01903-836035 The highlighted Items are specifically Included In the scope of RCR 472321 Attachment page 35

Att. 9: CA's to Address Programmatic/ Organizational Issues A. CA's from ERV RCA (Ref. 38) aligned with 02R18 Steam Dryer RCA CF. 2

Background:

CF #3 to ERV RCA: Organizational effectiveness and decision-making.

==

Description:==

The organizational contributors taken in aggregate demonstrate weaknesses in managing information, over-reliance on contractor-performed analysis, and applying a systematic approach to decision making for complex high-risk situations.

Causes Being Corrective Action (CA) or Action Item (ACIT)) Owner Due Date Addressed CF#3 Provide training to Corporate Engineering personnel on A8081 9/2012006 Organizational the requirement and application of OP-AA-106-101- TRLS effectiveness and 1006 for complex decision-making (CA# 23 revises OP-decision-making. AA-1 06-101-1006).

Complex engineering decisions which involve historical data, repeat equipment failure, risk and complex analysis shall require the use of OP-AA-106-101-1006 Operational And Technical Decision Making Process.

CA #20*

CF#3 Provide training to Quad Cities Engineering personnel A8461 9/02/2006 Organizational on the requirement and application of OP-AA-1 06-101- ESPT effectiveness and 1006 for complex decision-making (CA# 23 revises OP-decision-making. AA-1 06-101-1006).

Complex engineering decisions which involve historical data, repeat equipment failure, risk and complex analysis shall require the use of OP-AA-1 06-101-1006 Operational And Technical Decision Making Process.

CA #21 CF#3- from Ref. 38 Update HU-AA-1212 Technical Task Risk/Rigor A8053VP 6/16/2006 Organizational Assessment, Pre-Job Brief, Independent Third Party BWR effectiveness and Review, And Post-Job Brief to provide a link to OP-AA- (BRWRD) decision-making. 101-1006 for complex engineering decisions and/or products which involve historical data, repeat equipment failure, risk and complex analysis.

CA #22 CF#3- from Ref. 38 Training CRCs shall evaluate the need of providing A8068EN 6/16/2006 Organizational training to Exelon FLSs and above on the use and DES effectiveness and application of OP-AA-106-101-1006.

decision-making.

ACIT #4 CF#3- from Ref. 38 Submit update to OP-AA-106-101-1006 Operational And A8068EN 6/30/2006 Organizational Technical Decision Making Process Attachment B,. DES effectiveness and "Recognize Conditionse to include lessons learned from decision-making. the ERV root cause and documentation of all personnel involved in the final product.

Closure to include new assignment for processing of procedure change to Operations peer group.

CA #23 Attachment Page 36

Att. 9: CA's to Address Programmatic/ Organizational Issues B. CA's from ERV Actuator RCA (Ref. 38) & Replacement Dryer Fuel Impacts RCA (Ref. 37) aligned with Q2R18 Steam Dryer RCA - "Negative Design Impacts" Causes Being Addressed Corrective Action (CA) or Owner Due Date Action Item (ACIT))

CF#3 - from Ref. 38 Change the design input A8068ENDES 7/28/2006 Organizational effectiveness requirements to include upfront and decision-making. challenges to analysis and assumptions as part of the design review. The documents include CC-AA-1 03-1003 Owner's Acceptance Review Of External Configuration Change Packages and CC-AA-309 Control of Design Analysis. These front-end challenges shall be applied to all design changes and modifications independent of level.

CA #25 CAPR3 - from Ref. 37 Revise HU-AA-1212, "Technical Task Risk/Rigor Assessment..." to Revision issued complete include guidance on how to select by NCS.

what type of third-party review(s) are required. AT#: 330331-21 (complete)

CAPR4- from Ref. 37 Revise PC-AA-1008, "Issue Chartering". Add step 4.3.3.2 to require project teams - in the project NCS A8070PM 08/31/06 scoping phase - to review all CC-AA-102 attachments in order to determine scope additions and affected organizations. AT#: 281476-07 ACIT6- from Ref. 37 Evaluate the results of this root cause investigation for inclusion in the Project Management TAC. NCS A807OPM Complete Specifically, investigate training project managers on how to identify which departments to include on a project and when. AT#: 330331-22.

Attachment Page 37

ATTACHMENT 14 - of LS-AA-125-1001 (ATT. 10 of specific RCA 472321)

Root Cause Report Quality Checklist Page 1 of 2 A. Critical Content Attributes YES NO

1. Is the condition that requires resolution adequately and accurately identified? X

2. Are inappropriate actions and equipment failures (causal factors) identified? X

3. Are the causes accurately identified, including root causes and contributing causes? X

4. Are there corrective actions to prevent recurrence identified for each root cause and do X they tie DIRECTLY to the root cause? AND, are there corrective actions for contributing cause and do they tie DIRECTLY to the contributing cause?

5. Have the root cause analysis techniques been appropriately used and documented?. X

6. Was an Event and Causal Factors Chart properly prepared? X

7. Does the report adequately and accurately address the extent of condition in accordance X with the guidance provided in Attachment 3 of LS-AA-125-1003, Reference 4.3?

8. Does the report adequately and accurately address plant specific risk consequences? X

9. Does the report adequately and accurately address programmatic and organizational X issues?

10. Have previous similar events been evaluated? Has an Operating Experience database X search been performed to determine whether the problem was preventable if industry experience had been adequately implemented?

B. Important Content Attributes I. Are all of the important facts included in the report? X

2. Does the report explain the logic used to arrive at the conclusions? X

3. If appropriate, does the report explain what root causes were considered, but eliminated X from further consideration and the bases for their elimination from consideration?

4. Does the report identify contributing causes, if applicable? X

5. Is it clear what conditions the corrective actions are intended to create? X

6. Are there unnecessary corrective actions that do not address the root causes X or contributing causes?

7. Is the timing for completion of each corrective action commensurate with the X importance or risk associated with the issue?

Att. page 38

ATTACHMENT 14 Root Cause Report Quality Checklist Page 2 of 2 C. Miscellaneous Items YES NO

1. Did an individual who is qualified in Root Cause Analysis prepare the report? X

2. Does the Executive Summary adequately and accurately describe the significance of the X event, the event sequence, root causes, corrective actions, reportability, and previous events?

3. Do the corrective actions include an effectiveness review for corrective actions to X.

prevent recurrence?

4. Were ALL corrective actions entered and verified to be'in Action Tracking? *

5. Are the format, composition, and rhetoric acceptable (grammar, typographical errors, X spelling, acronyms, etc.)?.

• New AT items are created by CAP organization after MRC approval of RCA.

Att. page 39

BVY 04-113 Docket No. 50-271 r..-

Attachment 2 Vermont Yankee Nuclear Power Station Proposed Technical Specification Change No. 263 - Supplement No. 20 Extended Power Uprate - Meeting on Steam Dryer Analysis Meeting Presentation Slides NON-PRORIETARY Total number of pages In Attachment 2 (excluding this cover sheet) Is 99.

1 Exhibit 6

• Enteg Entergy VY Power Uprate Project Steam Dryer Updated Analysis Presentation September 29, 2004 Entergy, GE, SIA, CDI, Fluent 1

OEnt&W Brief Synopsis- Vermont

-I -

Yankee Power Uprate

• December 2001 - Start Project

• September. 2003I- Submittal

• Extensive Analyses/ Review

• Extensive Plant Modifications

• Operate Safely and Efficiently Now and iin the Future 2

Key Principles

• Reasonable assurance that VY shall operate safely and efficiently at uprated conditions

• VY Steam Dryer shall perform well at EPU and shall -NOT challenge system functions .important to. safety 3

ýýEntow.,

. Industry Operating Experience

• Multiple failures at Quad Cities

• 'Conventional Wisdom' significantly challenged

• Critical differences exist between plants

>.Major evolution of GE methodology

> Plant-specific. approach needed 4

OEn"tow~

Methodologies

• GE Methodology

• Generic Load Definition

• Response Spectrum Analysis

'Finite Element Model

=Plant-specific Approach

• Plant Specific Data

• Acoustic Circuit Model

• Vortex Shedding CFD, Model 5

11

,ýA Entou Key Safety iand Reliability Principles Requirements

• Plant-specific approach to Steam Dryer Issue "Deliberate, controlled, rigorous power ascension with plateaus

• Rigorous inspection plan: months of EPU Operation

• Closely follow industry initiatives 6

Presentation Overview Open session oVY dryer analysis changes summary:

• Plant-specific load definition

• Updated VY dryer analysis results oVortex Shedding investigation

• Results and comparisons

• Power. Ascension/ Dryer monitoring plan summary 7

Presentation Overview (coft)

• Closed session

• Detailed presentations:

• VY acoustic loads analysis

• VY plant specific load definition

• Comparison VY FIV measurements

• Dryer power ascension monitoring plan 8

'EnteW I

-

• Dryer Analysis Changes Summary N VY plant-specific load definition

• Acoustic Model Developed (CDI).

SPlant Specific Main Steam Instrument Data Obtained

• Data converted to Main Steam Pressures o Dryer Load Definition created

• GE Response Spectrum Developed o-GE Finite Element Model Run

• Results 9