ML20206L649
| ML20206L649 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 11/22/1988 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20206L645 | List: |
| References | |
| NUDOCS 8811300129 | |
| Download: ML20206L649 (10) | |
Text
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l Enclosure 1
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SUPPLEMENTAL SAFETY EVALUATION OF THE V0GTLE NUCLEAR POWER PLANT, UNIT 1 ,
SAFETY PARAMETER DISPLAY SYSTEM
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Background
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The staf f's review of the Vogtle, Unit 1 Safety Parameter Display System (SPDS) l was documented in Supplement No. 6 to the Vogtle 1 Safety Evaluation Report ;
(NUREG-1137). In that Supplement, the staff identified 14 open items. The open {
- items were referenced by license condition 2.C.7(b). The licensee was. requested i
- to evaluate each of the open items and propose actions to resolve them by i March 1, 1988. Cy letters dr.ted February 29, 1988 (Reference 1), June 15, 1988
- (Reference 2), July 27,1988 (Reference 3), and September 20,1988(Reference 4),
! Georgia Power Company submitted reports addressing license ccnditdon 2.C.7(b). I The staff also conducted conference calls with the licensee on July 16, July 20, [
and August 10, 1988.
Evaluation l The staff's evaluation of the licensee's submittals is consistent with
. Section 18.2, "Safety Parameter Display System," Revision 0 of NUREG-0800, !
"Standard Review Plan," (Reference 5). This evaluation is based on all infor- I mation available to date on the 14 open items listed in NUREG-1137, Section 18.2. l
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j The licensee conducted an operator survey regcrding the relevant SPDS open l
, items. During the operator survey, an average of 24 operators responded to (
l inquiries about the open items.
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. Each item and the staff's evaluation tollow: ,
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l 1. In the SpDS color-coding scheme, perceptual cues for challenges to critical safety functions (CSFs) are lost when a CSF parameter is of ques-tionable validity. Some other cue should be provided to indicate questionable data.
The licensee reported that the operator survey indicated no problem with the current us: of a purple Critical Safety Function Status Tree (CSFST) resulting from the computer encountering questionable data as input to the CSF. However, the licensee stated that the software logic has been
] changed to consider data "geod" if 2 inputs are in agreement. Previously, a "bad" parameter occurred when 1 of 3 or 1 of 4 channels deviated from the others. Operators did express a major problem with the high frequency of the purple status for the radiation monitor overview resulting from 1 many tests and repairs of individual radiation instruments. The licensee i committed to correct this problem by changing the software logic allowing i long-term out of service instruments to be deleted from the overview
- logic. During the second conference call, the licensee clarified that i with one key stroke, the operator could obtain information concerning i instruments deleted from the overview logic.
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1 Based on the licensee's connitment and the operator input, the staff firds
{ that the licensee has satisfactorily resolved this open item of the license
- condition.
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, 2. The containment isolation valve status display uses the color red for open and green for closed. This is consistent with the convention for valve
{ position lights, but is not consistent with the Sp0S convention of green l for safe, and red for unsafe. Conversely, use of the green / safe, red /
...a.e convention would violate the valve status color convention.
N erator input should be used in determining which convention is at ted.
4 i The licensee indicated that one operator during the operator survey l responded that the use of a non-standard color convention by plant computers had caused a problem. While the operator did not provide l
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details on the problem, it was noted that it did not result in the misinterpretation of a display. The licensee indicated that (1) the alarm position for containment isolation valves is open (and shown in red) and (2) generally, any parameter lei elarm is depicted in red. Thus, the licensee states there is no inconsistency between the two conventions.
- During the second conference call, the licensee confirmed that under
, normal operations the valve position for containment isolation valves 5
would be red (if open) and that if isolation was called for, and a valve
)
failed to close, it would continue to indicate red.
Based on the licensee's explanation and the operator input, the staff finds that the licensee has satisfactorily addressed this open item of the f
license condition.
- 3. Parameter alarm status is shown as green for normal, red for high (and low), and flashing red for high-high or low-low. Parameter alarm color coding might be more easily understandable if the CSF color-coding scheme of green-normal, yellow-alert, orange-severe challenge, and red-unsafe is used.
The licensee explained that the red / green color convention for parameter alarms is consistent with the normal / unsafe convention for CSFST colors and that the intermediate states of alarm corresponding to yellow (alert) and orange (severe challenge) are not defined for individual parameters.
Based on the licensee's explanation, the staff finds that the licensee has satisfactorily addressed this open item of the license condition.
- 4. Few prompts are currently used. Required user responses might be less artiguous if prompts were used to guide parameter value selection with keyboard arrow keys and to guide numerical inputs via keyboard.
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The licensee stated that the functions requiring keyboard input are outside the boundaries of the SpDS. The licensee reported that tha
- operator survey revealed no problems with respect to retrieving background i
data on computer points and utilizirg steam table calculations. The survey did reveal that operators disfavored the single option of scientific notation to set trend limits. The licensee comitted to provide a software change allowing either numeric or scientific notation.
I l Based on the licensee's comitment and explanation, the staff fir.ds the licensee has satisfactorily addressed this open item of the license condition.
- 5. The color of indicated setpoints and data plots is sometimes the same,
- making discrimination difficult or impossible. Acceptable operating levels are often not indicated on graphic displays.
Operators responded to the folicwing questionnaire item: "Unless a
! parameter is very near its operating limits, the limit line is not usually I
visible on the ERF trend display. Has this ever caused problems?" The
, licensee reported that operators indicated no problems with the limit lines. However, the licensee committed to extend the length of the limit line such that it is more visible and to report on the completion of this
! action in the Unit 2 Detailed Control Room Design Review (DCRDR) report.
- Regarding acceptable operating levels, the licensee stated during the
- second conference call that one key stroke by the operator can obtain l information on setpoints.
l l Based on the licensee's comitment and the operator input, the staff finds
} that the licensee has satisfactorily addressed this open item of the
! license condition.
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- 6. Default values are generally not presented.
The licensee indicated that during the survey, operators responded to the following question: "When selecting parameters for trending on the ERF comouter, would a display of the default values for the x and y coordinates [ bel beneficial [tnsert added]? The licensee reported that o ily two operat0rs responded that additional default values would be beneficial. During the second conference call, the licensee indicated that default values for x ard y coordinates (for example, time and temperature, respectively) are provided for all trend plots. Regarding the x coordinate (time), the default value is 10 minutes, however, the cperator could also select 2.5, 15, 30, 60, or 120 minutes. For the y coordinate, the licensee indicated that parameter value defaults are always to give the maximum resolution for the time period displayed.
Based on the above information and the operator input, the staff finds that the licensee has satisfactorily addressed this open item of the license condition.
- 7. Sometires the underline cursor which is displayed is dif ficult to locate.
The use of a block cursor should be considered as a solution. The licensee indicated that the current cursor will be retained because (1) only one supervisor identified the cursor as a problem, (2) the cursor is a hardware feature that can not be changed by sof tware, and (3) cursor selection errors are infrequent and inconsequential.
Based on the above information, the t'aff finds that the licensee has satisfactorily addressed this open item of the license condition.
- 8. Displays may contain numerous numerical values, some of which may be selected to bring up additional data screens, and some of which may not.
Differential coding of selectable and nonselectable values would avoid erroneous selections.
6-The licensee reported that one supervisor responded during the survey of operations personnel that a change in this area would be beneficial. The licensee cemitted to change the pointer selection algorithm allowing pre-viously nonselectable numbers in group displays to be selected. (
Based on the licensee'. commitment, the staff finds that the licensee has f satisfactorily addressed this open item of the license condition. ;
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- 9. Indication of current parameter values should be presented on status tree displays. !
The licensee reported that half of the operations personnel (about 12 individuals) responding to a 5.urvey question wanted the display of parameter values on CSFT displays. The licensee comitted to modify displays showing numeric values for parameters in instances where such 3 action would not result in crowding or cluttering affected displays and to report on the complatien of this action in the Unit 2 DCRDR report.
Durino the second conference call, the licensee reported that 23 of 25 displays would be modified. One display wtuld not be changed because it shows dichotomous data (yes or no) rather than numeric values. The second display would not be mod.ified because the licensee believes it would result in a cluttered display.
Based on the licensee's comitment, the staff finds that the licensee has satisfactorily addressed this open item of the license condition.
- 10. The cursor often moves to a location from which it must be moved for data input or selection of options. Unnecessary, additional interaction steps could be eliminated if a cursor could move directly to an active data input or option selection area.
The litansee documented that the software has oeen modified to autoinatically place the cursor at the first data field when data is entered.
Based on the above information, the staff finds that the licensee's action has satisfied this open item of the license condition.
- 11. Scroll keys would be easier to use if the forward and backward scroll keys were appropriately labeled.
The iicensee documented that the suggested corrective action has been completed.
Based on this information, the staff finds that the licensee's action has satisfied this open item of the license condition.
- 12. User errors and incertainty about the results of a selection might be reduced if parameter values selected by users (to produce subsequent screens) were displayed in reverse video for a second or two imediately after users designate such a selection through cursor positioning. The licensee indicated that operators responding to a survey question did not want the suggested feature because of concerns about desired displays being delayed thereby degrading system performance.
Based on the operator input, the staff finds that the licensee has
! satisfactorily addressed this open item of the license condition.
1 j 13. Establish and implement realistic rather than arbitrary criteria for interchannel comparison of redundant inputs. These values must be appro-1 priate both for adverse and normal operating conditions, and must be based l on anticipated instrument loop accuracies.
By conference calls of July 20, 1988 and August 10, 1988, the licensee indicated that (1) current interchannel comparison criteria are based on expectedindividualinstrumentloopaccuraciesand(2)accuraciesare based on design performance under normal operating conditions. The licensee indicated that its previous criteria was to consider a parameter "bad" if 1 of 3 or 1 of 4 redundant inputs for a parameter deviated from
8 the others. Deviation was defined as a 2 percent deviation from the full range of the instrument. The licensee also indicated that this criteria has been changed such that a parameter is considered "good" if two inputs are in agreement. Regardii.g the concern about greater uncertainty in parameter values during adverse conditions, the licensee stated that the emergency operating procedures (EOPs) address this concern by employing conservative values for process control and decisic points. By letter dated September 20, 1988, the licensee provided complete documentation of the disposition of this item.
Based on the information provided, the staff finds that the licensee has satisfactorily addressed this open item of the license condition.
14 Provide and discuss system availability.
In the letter dated February 29, 1988, the licensee stated that hardware failures related to the Process Effluent Radiation Monitoring System (PERMS) resulted in an inability to perfona the SPDS availability test.
In the letter dated June 15, 1988, the licensee stated the PERMS-related problems would be resolved by September 1,1988 and comitted to complete a 1000-hour availability test for the SPOS by December 31, 1988. Based on the comitment to corrplete this availability test and submit the results ;
to the NRC, the staff finds the licensee's comitment and schedule acceptable. !
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Q,n, elusion The staff has reviewed Georgia Power Company's submittals dated February 29, June 15, July 27 and September 20, 1988 respondina to the license condition !
2.C.7(b). The staff also conducted conference calls with the licensee on l July 15, July 20, and August 10, 1988. The staff finds that the licensee has :
satisf actorily addressed 13 of M open itr.ms. Regarding the remaining open j item, the licensee's letter of June 15, 1988 comitted to cernplete a 1000-hour l availability test for the SPDS by December 31, 1988. l
9 Based on the comitment to complete tnis availability test and submit the results to the NRC, the staff finds the licensee's comitment and schedule acceptable. Therefore, the staff concludes that the licensee nas fulfilled the requirements of license condition 2.C.7(b).
References
- 1. Letter from L. T. Gucwa (Georgia Power Company) to the NRC, Plant Vogtle, Unit 1. "License Condition-Required Information on Detailed Control Room Design Review and Safety Parameter Display System," February 29, 1988.
- 2. Letter from R. P. Mcdonald (Georgia Power Company) to the NRC, Plant Vogtle, Unit 1, "Safety Parameter Display System Availability Testing,"
June 15, 1988.
- 3. Letter from W. G. Hairsson (Georgia Power Companyi to the NRC, Plant Vogtle, Unit 1, "Co rige:Ma
. to Supplemental Summary Report on Report on Control Room Design Review," July 27, 1988.
- 4. Letter from W. G. Hairston (Georgia Power Company) to the NRC, Plant Vogtle, Unit 1, "Safety Parameter Display System," September 20, 1988
- 5. NUREG-0800, "Standard Review Plan, Section 18.2, "Safety Parameter Display System," Revision 0, September 1984