ML11356A023
| ML11356A023 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 12/22/2011 |
| From: | Hausler R Corro-Consulta |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| Shared Package | |
| ML11356A002 | List: |
| References | |
| RAS 21600, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01 | |
| Download: ML11356A023 (2) | |
Text
Tel: 972 962 8287 CORRO-CONSULTA Rudolf H. Hausler 8081 Diane Drive Kaufman, TX 75142 Mobile 972 824 5871 Fax: 972 932 3947 Flow Assisted Corrosion (F AC) a.od Flow Induced Localized Corrosion:
Comparison and Discus"ion Summary The computer model Checworks, used to manage aging of hot high pressure water and steam carbon steel lines was designed for Flow Assisted Corrosion (FAC) phenomena. Erosion Corrosion, Impingement and Cavitation are expressly excluded as unrelated to F AC. It is shown that the latter three corrosion phenomena are extensions ofF A C as the local flow intensity due to turbulence increases. The transition from one to the others is continuous and difficult to identify. F AC therefore is only one manifestation of Flow lnduced Localized Corrosion (FILC).
The localized corrosion rate under the umbrella ofF AC varies, per definition, almost linearly with fluid velocity; however, this linear relationship tra:.ositions
. into an exponential one as the local turbulence becomes such that erosional features become manifest. Whether such transition actually occurs following a power upgrade (PU) must be determined experimentally. It cannot be estimated from within Cbecworks.
It has been stated that the algorithms used to predict the F AC wear rate a:r:e based on extensive laboratory and plant data. This assures that the F AC wear rates predicted by Chec.works are accurate." This accuracy is said to be within+/- 50%.
However, this statement is based on an erroneous interpretation of the graphic representation of predicted vs. measured wear. Actually, the accuracy is within a factor 2. The measured wear ranges from twice the predicted to half the prediction.
- Partial review of the result from the pipe inspections using Checworks in 2003 and 2006 shows significant unexplained discrepancies.
I.
Introduction The direct testimony by Dr. Jeffrey S. Horowitz and Dr. James C. Fitzpatrick1) with*
regards to NEC Contention 4 - Flow Aceelerated Corrosion has raised a number of questions, which are being discussed below:
1l Joint Declaration of Jeffrey S. Horowi~ and James C. Fitzpatrick on N:EC Contention 4 -Flow-Aceelerated Corrosion, May 12, 2008.
6121.2008 l ofU lUffi Rebuttal RIV000019 Submitted: December 22, 2011 EXCERPT
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- measu(ed ones is derived from a representation of the data as shown in Figure 3 below. It is true that when the measured wear data are plotted against the predict~
ones most ofthe data points lie between two lineti that are plotted+/~ 50% off the 45 degree equivalency lines. This interpx-etation is totally misleading and scientifi~ally
- ctishonest.
First, one sees that there is no correlation between the predictions and the actual measuxeme:nts. Second, one also sees that measurements which we are made to believe are within 50% of the predicted value are really ~ce as large or larger;
- similarly~ on the other side one sees that 'measured values are half or less of the ptedicted ones, again a factor of2 different.
==
Conclusion:==
Tbe accuracy of Cheeworks is aueh that the meaaured values an within a factor of +/- two (+/.. l] of the predicted values rather t.han +/* SOO/o as elaba.ed.
A faotor-ef-twa difference between measured an(predicted corrosion [or corrosion rate]' can be quire significant with respect to selecting a particulax-item (line) for inspection during a given refueling outage. Indeed the report of tbe "EPRI Checwox-ks Wear Rate Analysis Results for Cycle 22B"15> shows that the time predicted to reach the critical miriimum. wall thickness in a.majority of cases is many years negative.
1bis means that the item should have failed a long time ago. Similarly, the remaining time to failure may be grossly overestilnated. But one will never know unless the proper inspections are performed and the com~uter model recalibrated, a process Dr.
Horowitz and Entergy seem to find irrelevant. 6>
Examination of the data from March 2003 (RFO 23) showed average and measured co:r:rosio:o. rates of the order of28 and 2lmpy, respectively, for-the outlet "P~l~lA on line 001*16-FDW-01. In May of2006 these same rates have come down to 7.524 and
- 5. 712 mpy, respecti'\\lely. 17) It is hard to see how this could have happened. There is in the program something called "Line Correction Factor." This factor bas been defined by Dr. Horowitz as the relationship between predicted and measured corrosion rate (see below18~. However in 2003 this factor was 0.649 and by2006 it had become 0.175. It is amazing to observe that fudge factors are built into the progratn which IS) ExhibitE-4-29.
J6) Joint J)ec)aration of Jefll'ey S. Horowitz and James C. Fitzpatrick on NEC Contention 4~Flow-:
Aooel~ Corrosion: A 34.
) Exhibit E-4-30..
- I) HOROWITZ'S TESTIMONY STATES THE f'OLLOWlNG ABOUT TilE ABOVE-MBNTIONED "CORREC'l10N F:ACTOR" AT A28:.. A Pass 2 Analysis compares the measu,red inspection xuults to 1he caJwlared wear tales and adjust! the F AC rate calculations to ac<:ount for the inspection.(8&tl}ts. The proJr1lOl does. dDs by comparing the predicted aanount of deeradation ~lth the m~
d~gradati?D ~
eada of the~
components. Usinc statistical methods, a correction factor l8 d.etemtined wbtcb.lS applied to all COlJlP01lCDb in a given pipe line - whether or not they were iRspected."
61.212008 8 ofll
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