ML20057E992
| ML20057E992 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 10/04/1993 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-89-10, NUDOCS 9310130461 | |
| Download: ML20057E992 (4) | |
Text
1 southem Nuclear Operatng company s
Post O'fice Box 1295 l
Birmingham, A!eama 35201 i
Te:ephone (CSI 868-5131 L
Southern Nudear Operating Company o... umy
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Farley Pro;ect the Southern eleCiHC SYSlem October 4,1993 Docket Nos. 50-348 10 CFR 50.54 50-364 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Joseph M. Farley Nuclear Plant Response to NRC Generic Letter 89-10 Supplement 5 Inaccuracy of Motor-Onerated Valve (MOV) Diaanostic Eauioment Pursuant to the requirements of NRC Generic Letter 89-10 Supplement 5, Southern Nuclear Operating Company (SNC) has reexamined the potentia!
inaccuracy issues associated with the use of motor-operated valve (MOV) diagnostic equipment at Farley Nuclear Plant (FNP). The purpose of this response is to identify the test equipment which has been used at FNP and to summarize the actions taken to address inaccuracy issues associated with the use of this equipment.
Since inception, the FNP MOV Program has used MOVATS diagnostic test equipment to test and set up MOVs as part of the Generic Letter 89-10 effort. The program has evaluated prior identified MOVATS inaccuracies and accounts for the most current MOVATS inaccuracies as provided in the ITI-MOVATS incorporated Equipment Accuracy Summary document (ER 5.0). These inaccuracies have changed several times during the implementation of the program. Each time the inaccuracy values are revised, SNC performs an evaluation to assess the impact on previously tested valves and to incorporate the latest inaccuracies into future MOV
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U.S. Nuclear Regulatory Commission Page 2 Diagnostic Equipment Used by FNP for MOVs The following MOVATS test equipment has been used in various combinations to test and set up gate and globe MOVs as pan of the Generic Letter 89-10 effort: Thrust Measurement Device (TMD)/ Load Cell (LC); Torque /Thmst Cell (TTC); Stem Strain Ring; Stem Strain Transducer; Stem Load Sensor; and the BARTS equipment for butterfly valvea.
Actions to Address Accuracy of MOV Diagnostic Equipment A summary of actions that SNC has taken in response to the issues identified in NRC Generic Letter 89-10 Supplement 5 is provided below.
ITI-MOVATS TMD/LC Open Versus Close Uncertainty This issue was originally addressed by SNC in response to a Westinghouse /ITI-MOVATS Potential Issue letter and later in response to NRC Information Notice 92-23.
A fundamental premise with regard to the original MOVATS methodology for MOV setup using the TMD/LC approach was that for a given spring pack displacement near equal thrust would be developed in both the open and close directions. During extensive testing at the MOVATS facility during the second half of 1991, this assumption was proven to be questionable under certain situations.
In order to assist equipment users in evaluating the effects of this "open versus close" uncertainty for MOVs previously tested using the TMD/LC methodology and to provide a basis for establishing total uncertainty for valves set up in this manner in the future, ITI-MOVATS provided a set of equations based on the testing program. These equations and the associated direction for use were issued in ER-5.2 Revision 0. This approach was endorsed by NUMARC in a guidance document issued in May 1992.
SNC has completed the evaluation of all previously tested valves set up using the TMD/LC methodology. The majority of the valves (approximately 85%) were evaluated using as a basis the predictive equations provided by ITI-MOVATS and endorsed by NUMARC. The remaining valves, consisting of certain large SB-equipped valves, used actual open/close FNP test data as a basis for evaluation for this style actuator / valve assembly. This alternative approach for large SB-equipped valves was utilized due to the excessively conservative nature of the ITI MOVATS predictive equations for these type MOVs. This excessive conservatism resulted from the scaling-up method used by ITI-MOVATS to extrapolate the results of the testing program (which utilized only small actuators) to cover large actuators.
U.S. Nuclear Regulatory Commission Page 3 Valves previously tested using the TMD/LC approach, were determined to be acceptable.
Any future testing performed using this methodology will consider the "open versus close" uncertainties in establishing the overall setup uncertainty.
Additional MOV Diagnostic Equipment Inaccuracy Issu_e_s The FNP MOV program takes into account the latest information on equipment inaccuracies that are available from various sources. SNC has performed an evaluation to nsess the impact on previously tested valves and has accounted for the inaccuracies associated with the following issues:
NRC Generic Information:
t IN 91-61 IN 92-23 IN 93-01 IN 93-54 Westinghouse /ITI-MOVATS Information:
Potential Issue - MOV Spring Pack Open Calibration Methodology Potential Issue - Inaccuracies in MOVATS 2151/3000 MOV Diagnostic Test Systems Potential Issue - Inaccuracies in Westinghouse MOVATS BART System and Stem Strain Ring White Paper - The Effects of Stem Lubrication on MOV Thrust Output MUTN 92 Stated Tolerance Change of Series 3500 Strain and Universal Input Card MUTN 92 Conversion Factor for Stem Strain Ring Used with 3500 System MUTN 92 Incorrect Stem Friction Coefficient in Signature Analysis Software MUTN 92 Incorrect Equation for Effective Cross-Sectional Area of a Threaded Stem MUTN 93 Correction to Full Span Values for the Torque Thrust Cell l
ITI-MOVATS Special Test Report 6.0 - Torque Thrust Cell Actuator Repositioning Effect The only issues raised on the accuracy of MOV equipment since the issuance of Generic Letter 89-10 Supplement 5 that are applicable to FNP involve the TTC and are identified in NRC Information Notice 93-54, ITI-MOVATS MUTN 93-01, and ITI-MOVATS Special Report ( 3. The issues deal with a potential increased uncertainty associated wd-MOV set-up using a temporarily installed TTC. This uncertainty is referred to as the
" actuator repositioning effect" A total of 70 valves at FNP have been set-up using a temporarily installed TTC.
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U.S. Nuclear Reaulatory Commis? ion Page 4 SNC has performed a review of the 70 va'ves to ensure the "as-left" set-up is acceptable considering the increased uncertainty asscciated with the actuator repositioning effect.
The valves were determined to be acceptable based on the overall set-up methodology employed at FNP.
SNC has contacted ITI-MOVATS and has confirmed that there are no outsianding issues-related to the accuracy ofMOV diagnostic equipment used at FNP that have not already been reviewed by SNC.
Respectfully Submitted, SOUTHERN NUCLEAR OPERATING COMPANY t
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Dave Morey orn is9:oedoc s
cc: Mr. S. D. Ebneter SWORN TO AND SUBSCRIBED BEFORE ME Mr. T. A. Reed Mr. M. J. Morgan THIS hl( DAY OF h,1993.
Awdr (Npt6h PMic My Commission Expires: '/-/9-74/
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