ML082130158

Submittal of 180 Day Steam Generator Report, Spring 2008

ML082130158
Person / Time
Site:	Calvert Cliffs
Issue date:	07/31/2008
From:	Flaherty M Constellation Energy Group, Nuclear Generation Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML082130158 (13)

Text

Calvert Cliffs Nuclear Power Plant 0:":

stellatlo ergy" Nuclear Generation Group July 31, 2008 U. S. Nuclear Regulatory Commission Washington, DC 20555 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 ATTENTION:

REFERENCE:

Document Control Desk Calvert Cliffs Nuclear Power Plant Unit No.1; Docket No. 50-317 Spring 2008 - 180 Day Steam Generator Report (a)

Calvert Cliffs Nuclear Power Plant Units 1

and 2

Technical Specification 5.6.9 In response to Reference (a), Attachment (1) provides the results of the steam generator tube inspection conducted on Calvert Cliffs Unit 1 in 2008.

This report includes the number and extent of tubes examined and indications identified.

Should you have questions regarding this matter, please contact Mr. Jay S. Gaines at (410) 495-5219.

Very truly yours,

~~-~~~

Mark D. Flaherty Manager - Engineering Services MDF/RDW/bjd

Attachment:

(1)

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report cc:

D. V. Pickett, NRC S. J. Collins, NRC Resident Inspector, NRC S. Gray, DNR

ATTACHMENT (1)

CALVERT CLIFFS UNIT 1, SPRING 2008 -

180 DAY STEAM GENERATOR REPORT Calvert Cliffs Nuclear Power Plant, Inc.

July 31, 2008

A AREVA 20440-12 (3/3012006)

ENGINEERING INFORMA ION ECORD 51 9077108 000 Document Identifier

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Title Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report PREPARED BY:

REVIEWED BY:

NAME Chris Waskey NAME Kent Colgan ~1~

Signature

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Technical Manager Statement: Initials

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Date 4 08 Reviewer is Independent.

Remarks:

This document transmits AREVA's input in support of Calvert Cliffs' 180 day report to the NRC on the condition of Calvert Cliffs Unit 1 steam generators. This report was prepared in accordance with the requirements of Calvert Cliffs Nuclear Power Plant (CCNPP) Technical Specification 5.6.9.

AREVA NP Inc., an AREVA and Siemens company Page 1 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000 Multiple Preparer/Reviewer Signature Block Pages/Sections Name (printed)

Signature P/R Date Prepared or Reviewed N/A N/A N/A N/A N/A Note: P/R designates Preparer (P) or Reviewer (R).

Page 2 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000 Record of Revisions Revision Date Pages/Sections Changed Brief Description 0

See cover N/A Original Issue Page 3 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000 Calvert Cliffs Nuclear Power Plant Unit 1 180-Day Report on the Spring 2008 Steam Generator Tube Inspection Page 4 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000 Calvert Cliffs Nuclear Power Plant Unit 1 - Spring 2008 During the Calvert Cliffs Nuclear Power Plant (CCNPP) Unit 1, spring 2008 refueling outage, both of the steam generators (i.e., SG11 and SG12) were inspected in accordance with CCNPP Technical Specification (TS) 5.5.9. The discussion below summarizes the results of the inspection consistent with the 180-day reporting requirements of Technical Specification (TS) 5.6.9. Bold wording restates the TS requirement, followed immediately by the required CCNPP information.

A report shall be submitted within 180 days after the initial entry into Mode 4 fo llowing completion of an inspection performed in accordance with the Specification 5.5.9, Steam Generator (SG) Program.

Initial entry into Mode 4 occurred on March 11, 2008; therefore, this report is required to be submitted by September 7,2008.

The report shall include:

a. The scope of inspections performed on each SG The following primary side inspections were performed in SG11 during the spring 2008 refueling outage:

Full length eddy current bobbin probe examination of 4,261 tubes (50%) including:

o All tubes within the pre-defined fan bar wear susceptible region (1,933 tubes) o All bundle periphery and no-tube-Iane locations two to four tubes deep (1,182 tubes) o A 1,146 tube sample (21%) of the remaining regions of the bundle Rotating eddy current probe examination of 21 special interest locations including:

o Ambiguous bobbin indications (6 locations) o Bounding examinations (11 locations) o All fan bar wear sized >15%TW (4 locations)

As-found and as-left visual examination s of the hot and cold leg primary channel head interior The following primary side inspections were performed in SG12 during the spring 2008 refueling outage:

Full length eddy current bobbin probe examination of 4,236 tubes (50%) including:

o All tubes within the pre-defined fan bar wear susceptible region (1,994 tubes) o All bundle periphery and no-tube-Iane locations two to four tubes deep (1,182 tubes) o A 1,060 tube sample (20%) of the remaining regions of the bundle Rotating eddy current probe examination of 29 special interest locations:

o Ambiguous bobbin indications (3 locations) o Bounding examinations (11 locations) o All fan bar wear sized >15%TW (15 locations)

As-found and as-left visual examinations of the hot and cold leg primary channel head interior Page 5 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000

b. Active degradation mechanisms found Three mechanical tube degradation mechanisms - fan bar wear (FBW), foreign object wear, and lattice support wear - were identified during this examination. No evide nce of corrosion degradation processes was identified.

c. Nondestructive examination techniques utilized for each degradation mechanism The following table identifies NDE examination techniques utilized for each identified degradation mechanism:

Table 1 - NDE Techniques Utilized for Identified Degradation Degradation Mechanism Inspection Type EPRI ETSS Bobb in (detection and depth sizing) 96004.1 (Rev. 11)

Fan bar & lattice support wear

+PoinFM(length sizing) 96910.1 (Rev. 10)

Bobbin (detection) 2709 1.2 (Rev. O):j:

Foreign object wear

+Point'(sizing in frees pan) 27903.1 (Rev. 0) (tapered football)

+Point'(sizing w/object present) 96910.1 (Rev. 10)

j:The bobbin probe was the primary means of detecting foreign objects and foreign object wear during this inspection. This ETSS is qualified to detect foreign object wear in the freespan (i.e., volurnetric degradation). Bobbin detectability close to the tubesheet was enhanced through the use of a three freq uency "turbo mix" which has been shown in the field to provide improved detection in this region.

d. Location, orientation (if linear), and measured sizes (if available) of service induced indications Fan bar wear (FBW) is a mechanical degradation process which produces volumetric tube wear at the interface between the ubend anti-vibration supports (fan bars) and the tubes. In total, 324 FBW indications in 272 tubes were identified in the CCNPP Unit 1 SGs during the spring 2008 inspection; an increase of approximately 2/3 from the 189 indications in 166 tubes identified during the 2004 inspection.

None of the identified FBW indications exceeded the Technical Specification plugging limit of 40 %

through wall. The distribution of FBW through wall (TW) depth among the two SGs was very similar, with SG12 depths tending to be slightly larger (Figure 1). The maximum indicated depth in both SGs was 23

%TW, while the maximum depth of newly reported FBW was 20 %TW in SG11 and 16 %TW in SG12.

The median growth rate of FBW reported during both the current and previous inspections was essentially zero in both SGs while the upper 95th percentile growth rate was only 0.8 %TW/EFPY in SG11 and 1.3 %TW/EFPY in SG12.

A combined total of six indications of potential foreign object wear and lattice support wear were identified during the 2008 inspection. These indications are described in Table 2. One of the affected tubes (SG11 R8 C130) contained a small indication of wear (7 %TW) at the 5th lattice support on the hot side along with an indication of either a lattice bar burr or a small foreign object adjacent to the contact point between the tube and lattice bar. The tubes surrounding SG11 R8 C130 were examined with rotating probes and no foreign object or wear indications were identified. Because the condition in SG11 R8 C130 could not be investigated on the secondary side, a conservative decision was made to preventively stabilize and plug the tube. While no other indications of potential loose parts were Page 6 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000 identified during this examination, two other indications of wear attributed to migratory foreign objects were identified (Table 2). Both tubes experienced wear on the hot leg in the freespan between the top of the tubesheet and the first lattice support. Bounding rotating probe examinations were performed in the tubes surrounding the affected tubes and no indications of wear or foreign objects were identified. Three indications of lattice support wear were also identified (Table 2). The maximum indicated depth of these indications was 14 %TW.

Page 7 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000 Figure 1 -- Fan Bar Wear Throughwall Depth Distribution 36 34 32 30 28 26 24 22 i?:'

20

c 18

l 0

16 14 12 10 8

6 4

.. I In I

2 3

4 5

6 7

8 9

10 11

• Steam Generator 11 o Steam Generator 12 n nn.

n n.n 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Wear Depth (%TW)

Table 2 - Foreign Object and Lattice Support Wear Foreign Bobbin Depth Object Steam Amp litude Circ.

Axia l Sizin g Maximum Cause of Potentially Plugged I Generator Row Column (Volts)

Elevatio n Offset (in)

Extent (in) Extent(in)

ETSS Depth (%TW)

Damage Present?

Stabilized?

11 8

130 0.13 05H

-1.51 0.30 0.23 96910.1 7

Foreign Object Yes' Yes Wear 11 78 94 0.19 04H 0.51 0.26 0.25 96004.1 11 Lattice No No Support Wear 11 126 114 0.11 TSH 0.95 0.33 0.29 27903.1 26 Foreign Object No No Wear 12 106 134 0.64 TSH 7.12 0.39 0.39 27903.1 30 Foreign Object No No Wear 12 122 86 0.20 07e 1.07 0.27 0.18 96004.1 9

Lattice No No Support Wear 12 134 88 0.15 02H

-1.53 0.33 0.27 96004.1 14 Lattice No No Support Wear

¥ Lattice support burr or small foreign object.

Conse rvat ively treated as foreign object.

Note : None of the indications identified in this table were present in the 2004 ECT data.

Page 8 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000

e. Number of tubes plugged during the inspection outage for each active degradation mechanism One tube, in SG11 (Row 8 Column 130) was preventively stabilized and plugged due to a potential foreign object or lattice bar burr indication adjacent to a small wear indication (see Table 2). This is the only SG tube that was plugged during the 2008 refueling outage. There are no other plugged tubes in the Calvert Cliffs Unit 1 Steam Generators.

f. Total number and percentage of tubes plugged to date Only one tube has been plugged to-date in the CCNPP Unit 1 SGs. That tube was plugged in SG11 during the 2008 refueling outage (see response (e) above).

Table 3 - Tube Plugging Summary Tubes Installed Tubes Plugged To-Date SG11 8,471 1 (0.012%)

SG12 8,471 0(0.000%)

Total 16,942 1 (0.006%)

g. The results of condition monitoring, including the results of tube pulls and in-situ testing The condition monitoring assessment is summarized in Figures 2, 3 and 4. The figures provide the condition monitoring limit curves corresponding to the NDE technique employed for each degradation type. All reported degradation falls below the applicable condition monitoring curve and therefore satisfies the Technical Specification structural performance criteria. This provides reasonable assurance that none of these volumetric flaws would have leaked during a main steam line break, thereby satisfying the accident leakage performance criteria. Since this conclusion could be reached analytically using NDE inspection results with a full accounting of significant uncertainties, no in-situ pressure testing was required to demonstrate structural and leakage integrity. During the past operating cycle, no measurable primary-to-secondary leakage was observed, thereby satisfying the operational leakage performance criteria.

The results of the 2008 inspection and the condition monitoring conclusions confirm that the 2004 operational assessment was appropriately bounding. No tubes were removed from the SG for destructive examination.

h. The effective plugging percentage for all plugging in each SG There are no sleeves installed in the CCNPP Unit 1 steam generators, therefore the effective plugging percentage is the same as stated in (f) above.

Page 9 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000 Figure 2 -- SG11 FBW Condition Monitoring (ETSS 96004.1) 75 70 65 60 55 50

~

45

~s 40 e,

0 35 30 25 20 15 10 95/50 CMLimit Wear (Max Depth, Assumed Length)

Wear(MaxDepth, Measured Length) 5 O+--.---.,.---,--..,...--.---.,.----,.--..,---,..-----,----r----,--,----,--+----r---r----,---.----!

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 Axial Length (in)

Figure 3 -- SG12 FBW Condition Monitoring (ETSS 96004.1) 95/50 CMLimit Wear (Max Depth, Assumed Length)

Wear (Max Depth, Measured Length) 75 70 65 60 55 50

~

45 C

i 40 0

35

s 30 25 20 15 10 I

O+----,,----.---r---,--.---.,.---,--..,---,..---,.-

---r---.---,------,-

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 Axial Length (in)

Page 10 of 11

Calvert Cliffs Unit 1, Spring 2008 - 180 Day Steam Generator Report Document No. 51-9077108-000 Figure 4 -- Foreign Object and Lattice Support Wear Condition Monitoring

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02 O~

OA 05 OB 03 OB O~

1~

lj 12 1~

lA 15 lB 13 lB 1~

2 ~

Axial Length (in)

- - 95150 CMLimil - ETSS 27903.1 Wear - 27903.1 (MaxDepth)

- - - - 95150CMLimil-ETSS 960 04.1 Wear - 96004.1 (MaxDepth) 95150 CMLimil-ETSS 96910.1 Wear - 96910.1 (MaxDepth)

'- -; =-"'.........

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-=. --..:......................

- - - - - -=:..::.--.=--..:......:. -....:

• SG12 Rl06 Cl 34

• SGll R126Cl14

• SG12 Rl34 C68 SG11 R78C94

• SG12 1<122 USc

• SGll R8 C130 85 80 75 70 65 60 55

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50

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45

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35

s:

30 25 20 15 10 5

0 0.0 0.1 Page 11 of 11