ML061220436

Attachment 3 to Comanche Peak Conference Call

ML061220436
Person / Time
Site:	Comanche Peak
Issue date:	05/18/2006
From:	Office of Nuclear Reactor Regulation
To:
Thadani M, NRR/DLPM, 415-1476
References
Download: ML061220436 (5)

Text

CPSES SG Coziference cafl follolw-ip inllfortionPag]of PaqAe I of 5 Answers to follow-up questions from The CoI1aache Peak (CPSES) SG ISI conference call From die 700% SG ISI conference call held on l0:20&05, CPSES had 3 outstanding questions ro which we ag-reed to provide further information. These 3 questions were:

1. Discuss the resullts from +Pr expanlsionl of u-bend region,

2. Provide further information concerniincg any in situ test(s) and discuss the results. and

3. Discuss performlance of Primary and Secondary Analystsswith respect to freespan axial indications.

Answers to these questions are provided on the following pages.

Attacrat 3

CPSES SG Conference call follow-up informariono P32C 2 of '

1. 1 Expanded +Pt in u-bend region No further indications w,/ere observed after +Pt inspection expansion to Row 25 in SG4.

!2 In SItM Pressur'e Testhni Results Discussion Duringa the Comanche Peak IRFI 1 outae, two tubes were selected for in simu pressure testing evei thoough these locations were not required test locations per the EPRI In Situ Pressure TestiIig Guideline. Revision 2. The locations tested were SGI R3.2 CO9 and SGI R24 C22. Both tubes were tested in a full tube miode. R32 C99 includes the longest flaw length reports for this mechanism: R24 C22 includes the largest +Pt amplitude responses for this mechanism.

R32 C99:

This tube contained freespan axial ODSCC indications similar to the type of indications observed at Comanche Peak Unit 1 since the IRF09 (2002) outage. This rube differed in that the crackl density per support to support span was higher than observed on past tubes. In addition, The tube span fromu C9 to C10 contained a continuous length ODSCC flaw approaching 36 inches. Due to the cbservation of this length, which was previously unobserved at Comanche Peak, it was decided to conservatively pressure test the tube. The temperature -adjusted 3 times nonual operating pressure differential proof test pressure for Comanche Peakl I is 4266 psi. A conservative proof test pressure of 4350 psi was selected based on a conservative estimate of the limitii bzurst pressture for R32 C99. Tle pressure test cycle incluided lold times at 1430. 2250, 2S41. 3350. 3S0. and 4350 psi. wvith the proof test pressure held for 5 minutes. In addition. the tube was pressure tested to an oveipressure condition of 4650 psi. or 300 psi above the proof test pres ure. No leakage or burst was reported.

The post in situ RPC examination of this tube indicates that the +Pt flaw amplitudes were relatively unchanged from the pre test condition. The largest amplitude change of 0.11 volt occurred for the largest pre test signal. This clhange is consistent with past in situ pressure tests of freespan ODSCC signals. including tubes pulled for this mechanismn durino the IRF09 outage.

Flaw lengths were not changed by the pressure test. The results of this test confirm the results of the pulled rube sizing methodology. The limited flaw change due to presstue testing indicates that the flaw was not plastically deformed, and that inmaiinent burst was not realized.

R-14 _ 22:

This tube also contained freespan axial ODS CC, however the reported flaw lengthls and flaw density per span length were significantly less than those observed for R32 C99. No leakaee or blurst at '4350psi w as oblserved. The test cycle for tlis tube did not incltde overpressiure. The post test IPC data indicates similar results as R32 C99: limited flaw amplitude change and no flaw lengith change post in situ pressure test.

In conclusion the in situ pressure test results and observations of limited change post test indicate that substantial margins against the performance criteria are provided for these indications.

CPSES SG Conference call follow-up informnaTionP pa --, t 3 0 : 5,

1. 3 Tertiarv Review of Bobbin Coil Data Using Automated Data Screening (includes discussion of Primary and SecondarV Analyst performance)

On October 17%h 2005 during a special interest MRPC examination of Row 32 Column 99 in So 1 axial flawss were detected immediately above and below the support spans scheduled for test.

The bobbin coil analysis had reported two distorted freespan indications (DFI) at elevation C7

• 33.29" and C8 + 10.07". The scheduled test extent was C7 to C9. In order to ensure that the entire span is tested with MVRPC the scheduled test extent includes approximately two inches above the upper support plate and two inches below/ the lower support plate. The MRPC test confirmed single axial indications (SAI) at the location of the two bobbin coil DFI signals, however no distorted bobbin signals had been reported at the location of the two additional flaws adjacent to the tube supports. Another special interest MRPC examination was subsequently scheduled on October 1 9th with a programmed test extent of C6 to C10. This data showed an SAI signal response extending for an estimated 33.53" along the span of tubing between C9 and C10. The maximum signal amplitude along the length of the flaw is 0.25 volts. A review of the bobbin coil data showed low level signal responses along this area which had not been reported by either of the evaluators performing rnanual data analysis. As manual analysis of such low level signals can be challenging it was decided to run the bobbin data through the Westinghouse Automated Data Screening (ADS) computer software to determine whether the signals in question could be reported without excessive false positives. The bobbin data for the other six tubes with freespan axial ODSCC were also processed and the sorting parameters were adjusted such that the previously reported DFI signals were identified as well as the low level signals above C9 in Rowv 32 Column 99. Additional DFI signals were reported in two of these tubes that had not been reported by the manual analysts.

The freespan flaws in the Comanche Peak Unit 1 site specific performance demonstration were also successfully detected. The optimum ADS signal extraction voltage was determined to be 0.15 volts on a filtered 300 KHz channel.

Star:ing on October 21 st the bobbin data from all four steam generators was processed througli ADS. All additional freespan signals were evaluated by two independent resolution analysts including a review of the first ISI data to determine change. This resulted in a total of 167 additional DFI calls between the four steam generators. All of the tube locations with the DFI calls were tested with MRPC to determine whether a flaw was present. Of the 167 DFI signals, one was confirmed as a low level flaw with an amplitude of 0.08 volts on the plus point coil (SG I Row 35 Column 37).

Table 1 provides the examination results for freespan flaws prior to the tertiary review by ADS.

Primary and Secondary analysis is compared to Resolution results for the purpose of whether one or both analysis parties reported the DFI signal. The plus point signal amplitude and asscciated flaw length is also listed to provide perspective on the magnitude of each flaw.

Table 2 provides the same information after the ADS review. Most of the additional indications detected are indicative of low level axial ODSCC.

CPSES SG Co'nferenlce call follow-uLp infformatioll Pa-_e 4 of 5

1. 3 lcontinued, TXU 1RFl 1 Steam Generator Examination Table 1 Bobbin Analysis Detection of Freespan ODSCC - Manual Analysis Only

'iG Row Col Call Location +Pt Vrnax Length Primary Secondary

-1 32 99 DFl H1 + 17.97 0.10 0.34 0 X

_ DFI H7 + 8.88 0.10 0.34 0 X

_ __ DFl H7 + 30.04 0.22 0.62 0 X DFI C8 + 10.07 0.11 0.30 0 X DFl C7 + 33.29 0.09 0.21 0 X

_ 15 25 DFI C7 + 9.08 0.07 0.15 0 X 1 6 50 DFI C10 + 4.40 0.11 0.20 X X

, 30 65 DFI H3 + 33.77 0.24 1.05 X 0

. 11 91 DFI H10 + 9.79 0.10 0.55 0 X 4l 24 22 DFI C8 + 34.57 0.11 2.20 X 0

__ DFI C8 + 27.68 0.42 3.40 X X

= _ DFI CB + 26.58 0.06 Same flaw X 0 4 9 39 DFI C8 + 10.25 0.14 0.12 X X DI i C8 + 12.87 0.14 0.18 X X a__

__ FD C8 + 41.29 0.17 0.19 X X

_______I_

X = Detected O = Not Detected

• 15 DFI locations that are SAI by +Point

• 5 called by both primary and secondary

• 10 called by either primary or secondary (PSES SG Conference call follow-up informationP Pace 5. of s t*3 (continued)

TXU 1RF 1 Steam Generator Examination Table 2 Bobbin Analysis Detection of Freespan ODSCC - With Computer Screening

-,G Row Col Call Location +Pt Vmax Length Pri Sec ADS

_1 32 99 DFO Hi + 17.97 0.10 0.34 0 X x

_ _ DFI H7 + 8.88 0.10 0.34 0 X X DFI H7 + 30.04 0.22 0.62 0 X X

- DFI C9 + 30.39 same ind as below 0 0 X

_ DFI C9 + 11.23 0.25 33.53 0 0 X

- DFI C9 + 8.28 same ind as above 0 0 X DFI C9 + 1.66 same ind as above 00 X

__ DFI C8 + 23.98 0.09 0.60 0 0 X

- DFI C8 + 10.07 0.11 0.30 0 X X

__ - - DFI C8 + 7.20 0.12 1.76 0 0 X

_ - DFI C8 + 2.22 0.08 0.54 00 X

_ - - DFi C7 + 41.01 0.07 0.75 0 0 X

_= - DFI C7 + 39.71 0.22 0.81 0 0 X

- DFI C7 + 38.49 0.15 1.11 0 0 X

- OHF C7 + 33.29 0.09 0.21 0 X X

__ - DFI C7 + 27.60 0.07 0.24 0 0 X 1 - DFI C7 + 12.78 0.10 0.54 0 0 X

_ - DFI C7 + 3.54 0.11 0.39 0 0 X

__ - DFI C7 + 2.49 0.08 0.54 0 0 X

_= DFI C6 + 10.68 same ind as below 0 0 X DPI C6 + 5.46 0.24 19.61 0 0 X

__ DPI C6 + 3.19 same ind as above 0 0 X

- DFI C6 + 1.25 same ind as above 0 0 X DFI C5 + 14.25 same ind as below 0 0 X DFI C5 + 13.20 same ind as below 0 0 X DPI C5 + 12.82 0.19 4.23 0 0 X DFI C5 + 9.51 0.11 1.54 0 0 X DFI C5 + 8.90 same ind as above 0 0_ X

_ 15 25 DFI C7 + 9.08 0.07 0.15 0 X 0

_ 6 50 DFI C1O + 4.40 0.11 0.20 X X X 1 35 37 DFI C8 + 22.39 0.08 1.28 0 0 X

_ 30 165 DI H3 + 33.77 0.24 1.05 X 0 X

, 11 91 DFI H10 + 9.79 0.10 0.55 0 X X

__ 24 22 DFO C8 + 34.57 0.11 2.20 X O X DFI C8 + 27.68 0.42 3.40 X X X DF- C8 + 26.58 same ind as above X O X

_9 39 OHI C8 + 41.29 0.17 0.19 XX X

_= DF1_I C8 + 41.23 same ind as above 0 0 X

_= _ O C8 + 12.87 0.14 0.18 X X X

_ _ _ H C8 + 12.79 same nd as above 0 X

_ _ DFI C8 + 10.25 0.14 0.12 X X X

= DFI C8 + 10.16 same ind l as above 0 0 X