ML12286A087
| ML12286A087 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 10/15/2012 |
| From: | Aleksick R, Horowitz J - No Known Affiliation, CSI Technologies |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| References | |
| RAS 23613, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01 | |
| Download: ML12286A087 (13) | |
Text
Overview of CHECWORKS Jeffrey S. Horowitz, ScD Robert M. Aleksick Indian Point Energy Center ASLB License Renewal Hearing ASLB License Renewal Hearing Presentation Tarrytown, New York 1
y October 15, 2012
=
Background===
Surry Unit 2 accident - December 1986
Demonstrated need to inspect single-phase piping
Limited US inspection programs were in place for single-phase FAC
In 1987 EPRI & NUMARC committed to develop a
In 1987, EPRI & NUMARC committed to develop a computer program (CHEC) to assist in selecting inspection locations in BWRs and PWRs d
d l d f
NUMARC issued programmatic guidance including use of CHEC or equivalent method.
CHEC later revised and enhanced as CHECWORKS 2
CHEC Development Approach
The EPRI CHEC development team gathered data from Europe:
Laboratory data from CEGB (England)
Laboratory data from CEGB (England)
Laboratory data from EDF (France)
Plant and laboratory data from Siemens (Germany)
All known laboratory data were obtained
Used limited US plant data U
d i ti i
tifi k l d t
t t
Used existing scientific knowledge to structure correlation between piping wear and plant operating parameters 3
EPRI released CHEC 7 months after Surry accident
Mathematical Analogue
Extending the Keller and the Kastner correlations
& the Berge model, Chexal and Horowitz designed and implemented a new algorithm to be used in a d p e e
ed a e
a go o be used the CHEC program.
FAC Rate = F1
- F2
- F3
- F4
- F5
- F6* F7 Wh
Where:
F1 = Temperature factor
F2 = Mass transfer factor
F3 = Geometry factor
F4 = pH factor
F5 = Oxygen factor F
Allo fa to 4
F6 = Alloy factor
F7 = Void fraction factor (CHECMATE & CHECWORKS)
Improvements Over Previous Approaches
CHECWORKS:
Uses a larger database of experimental and plant data.
Incorporates local conditions through water chemistry modeling (pH and dissolved oxygen), void fraction and flow modeling (velocity, pressure and enthalpy).
U t
f t
f l
t d t ith i i ht f
Uses geometry factors from plant data with insight from copper modeling tests.
CHECWORKS algorithm has been continually validated and refined, as necessary, against new plant and laboratory data.
5
CHECWORKS Input Parameters
Heat Balance Diagram - one time input
Global plant conditions - power level, thermodynamic conditions water chemistry and thermodynamic conditions, water chemistry and operating time for each operating period
Plant component conditions - component p
p geometry, material, size, wall thickness, operating and design conditions, flow rate and quality (if not available from flow analysis)
Component replacement information (if applicable) i d
(if li bl )
6
Inspection data (if applicable)
Plant Modeling
The plant is divided into a number of lines having roughly the same water chemistry and operating conditionse.g.,
feedwater between feedwater heaters.
Depending on the complexity and amount of resistant material in the plant, there are normally 25 to 50 of these analysis lines.
Using the global information, the wear is calculated for each operating period, and the lifetime wear of each component is calculated by summing up the calculated amounts of wear for each period.
each period.
Not all of the lines in a plant are suitable for analysis using CHECWORKS.
7
How CHECWORKS Works
CHECWORKS is designed to handle:
Changes in operating conditions (e.g., flow rate)
Changes in water chemistry (e g oxygen concentration)
Changes in water chemistry (e.g., oxygen concentration)
The two basic design considerations are to:
Model changes in conditions, including the ability to g
g y
forecast the impacts of such changes.
Integrates the treatment of inspected and non-inspected components.
CHECWORKS is one tool to help select inspection locations.
8
How CHECWORKS Works (cont.)
Pass 1 is an analysis done without considering inspection data.
A Pass 1 analysis is typically used to select initial inspection locations.
The user has the option to include
The user has the option to include inspection data - this is known as Pass 2.
For Pass 2, the user can compare how well the
d h h programs predictions match the measurements.
Pass 2 predictions go through the center of the data (i.e., program is best estimate).
9
(
, p g
)
Analyzing Predicted and Observed Data
Part of the Pass 2 feedback is the program-computed line correction factor (LCF).
The LCF is computed separately for each
The LCF is computed separately for each Pass 2 line.
The user also can view predictions versus p
measurements on various plots and tables allowing the identification and examination of any outliers.
The user then decides whether lines are
The user then decides whether lines are calibrated or not-calibrated using guidance found in NSAC-202L R3, considering the LCF and other factors 10 other factors.
Program Outputs For each component, in each line analyzed, CHECWORKS provides:
y p
Predicted wear rate Predicted thickness Predicted thickness Predicted time to reach critical thickness F
P 2
l i
CHECWORKS For Pass 2 analysis, CHECWORKS provides the LCF and measured thicknesses 11 thicknesses
Program support
EPRI conducts periodic training in FAC issues and the use of CHECWORKS.
EPRI maintains hotline support through a phone line and website.
EPRI sponsors a FAC interest group - CHUG -
EPRI sponsors a FAC interest group - CHUG -
which holds two meetings a year.
CHECWORKS is periodically updated to meet user p
y p
feedback.
12
Thank you for your attention.
Questions?
End of presentation 13