AECM-85-0149, Forwards Rev 0 to App a of Spec MP&L-M-189.1, Max Stroke Times for Power Actuated Valves, Providing Max Allowable Stroke Time Values for All Power Operated Valves Subj to Inservice Testing & Addl Relief Requests
| ML20128K621 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 06/28/1985 |
| From: | Dale L MISSISSIPPI POWER & LIGHT CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20128K626 | List: |
| References | |
| AECM-85-0149, AECM-85-149, NUDOCS 8507110085 | |
| Download: ML20128K621 (4) | |
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MISSISSIPPI POWER & LIGHT COMPANY
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Helping Build Mississippi hiB&HalMdB P. O. B O X 164 0, J A C K S O N, MIS SIS SIP PI 39215-1640 June 28, 1985 NUCLEAR LICEN$ LNG & SAFETY DEPARTMENT U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D. C.
20555 Attention:
Mr. Harold R. Denton, Director
Dear Mr. Denton:
SUBJECT:
Grand Gulf Nucicar Station Units 1 and 2 Docket Nos. 50-416 and 50-417 License No. NPF-29 File: 0290/M-189.1 IST Pump & Valve Program - Maximum Stroke Times & Additional Relief Requests AECM-85/0149 Mississippi Power & Light (MP&L) submitted the Grand Gulf Nuclear Station (GCNS) Unit 1 Pump and Valve Inservice Test (IST) Program to the NRC on August 26, 1983. During a working meeting conducted on November 27, and 28, 1984 between MP&L and members of your staff to discuss the program, the NRC staff requested that MP&L provide a list of maximum allowable stroke time values for all power operated valves subject to inservice testing. MP&L's response to the NRC staff's request is provided in Attachment 1 to this letter. MP&L has also identified the need for three (3) additional relief requests (Attachment 2) to Specification MP&L M-189.1 Rev. O.
These relief requests are in addition to those provided in MP&L letter AECM-85/0121 dated June 17, 1985.
Attachment I describes two methodologies which were utilized in calculating the maximum allowable stroke time values. The maximum value was computed by a statistical method (Method 1) when there was sufficient data to ensure a statistically valid base.
In the case where a " normal" range could not be determined, a slightly larger margin was added to the average stroke time (Method 2).
For some of the subject valves listed in Attachment 1 the maximum allowable stroke times utilized are the maximum isolation times in CGNS Technical Specification Tables 3.6.4-1 and 3.6.6.2-1.
The maximum allowable stroke time for the valves listed in Attachment 1 and the relief requests provided in Attachment 2 to this letter will be incorporated into the CGNS IST program by commercial operation, which is presently scheduled for July 1, 1985.
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AECM-85/0149 Page 2 If there are any questions, please contact this office.
'Yours truly, L. F. Dale Director KED/MLC/JGC:dem Attachment cer Mr. J. B. Richard (w/a)
Mr. O. D. Kingsley, Jr. (w/a)
Mr. R. B. McGehee (w/a)
Mr. N. S. Reynolds (w/s)
Mr. G. B. Taylor (w/o)
Mr. R. C. Butcher (w/a)
Mr. James M. Taylor, Director (w/a)
Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Dr. J. Nelson Grace, Regional Administrator (w/a)
U. S. Nuclear Regulatory Commission Region II 101 Marietta St., N. W., Suite 2900 Atlanta, Georgia 30323 Mr. Herb Rockhold (w/a)
EG&G Idaho, Inc.
P.O. Box 1625 Idaho Falls, Idaho 83415 J0P14AECM85061401 - 2
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.9 Contained herein are maximum allowable stroke time values for all power 6
operated valves subject to inservice testing.
The " Safety Position" indicates the position to which the valve must be stroked and timed.
Based on ASME Section XI, IWV-3417, an increase in stroke time of 50% for quick acting valves or an increase of 25% for slower valves is well within acceptable limits since no immediate action is required. Therefore, the maximum stroke times have been computed as follows.
Method 1 For groups of valves where sufficient data exists to ensure a valid statistical base, the maximum is computed by the greater of adding 3 standard deviations to the mean 02) to define the normal range and then adding 10% to that normal range or a 10% increase beyond the Code " alert" values (1.35 1 for stroke times exceeding 10 seconds and 1.6 R for stroke times less than or equal to 10 seconds). The " alert" values of the Code will be observed.
The mean (Y) is not subject to frequent change, but is subject to periodic updating as the database grows.
Method 2 The " normal" range cannot always be determined for a group or for
' individual valves or the valves may not follow the trends discussed above.
In this case, a slightly larger margin is added to the average stroke time by use of the following formula.
2 Maximum = 2.058R - 0.0272 for x lecs than or equal to 26 seconds This is derived from the relationship in Figure 1.
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Y (MULTIPLIER) 1.35- -
2 26 X(AVERAGE STROKE TIME)
FIGURE 1
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This method avoids overlap which occurs with the range method of Section XI.
The maximum for valves with average stroke times of greater than 26 seconds is (1.35)R.
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Regardless of which method is used, the following rules apply.
' ' i) Maximum $E Analytical Requirements
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.ii) Maiiiiiium "$i""
TeEhnical" Specific'tions *'
a iii) Maximum $i (1.25) R (Design Specification Value) 1
- Note: In cases where the Technical Specifications are more conservative than the methods described above, the Technical Specification limit will be used unless a Technical Specification change is made.
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MP&L plans to use Method I wherever possible in the future as more is learned about valve behavior, and information is gathered for each specific valve and actuator combination.
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