ML20211H268
| ML20211H268 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 02/12/1987 |
| From: | Papanic G YANKEE ATOMIC ELECTRIC CO. |
| To: | Mckenna E NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| FYR-87-016, FYR-87-16, NUDOCS 8702260129 | |
| Download: ML20211H268 (6) | |
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YANKEE ATOMIC ELECTRIC COMPANY w ?,ho"'(6")*'~oo VX 710-380-7619 3-y. :,
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1671 Worcoster Road, Framingham, Massachusetts 01701 2.C2.1 A. Q.
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February 12, 1987:
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FYR 87-016 4
U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Attention:
Eileen M. McKenna, Project Manager
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Project Dircctorate #1 s
Division of PWR Licensing - A
References:
(a) License DPR - 3 (Docket No. 50-29')
(b)
U.S.N.R.C. Letter to YAEC, dated November 18, 1986
Subject:
SAFETY PARAMETER DISPLAY SYSTEM (SPDS)
Dear Ms. McKenna:
In Reference (b), you identified that Yankee would respond to the issues raised in Enclosure 1 by February 12. 1987 Attached to this letter is our response.
?) t5 We trust that you will find this information satisfactory; however, should
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you have any questions, please contact us.
t Very truly yours, YANKEE ATOMIC Fi,ECTRIC COMPANY 4/
J George P anic, Jr
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Senior Project Engineer-Licensing Yankee Project GP/gbc i
f cc: USNRC Region 1 USNRC Resident Inspector, YNPS 8702260129 870212 DR ADOCK 05000029 Iff PDR
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ATTACHMENT Response to NYR 86-260, dated November 18, 1986 This Supplemental Safety Evaluation Report (SER) concerns the Yankee plant's Safety Parameter Display System.
The SER's conclusions, where a response is required, are addressed below.
Item 2 Concern:
"The SPDS is conveniently located as long as YAEC commits to maintaining or improving the relative position, orientation, and I
visual access of the containment isolation status display with respect to the SPDS station."
Response: Yankee will maintain the existing physical positions, and thus the-visual access, between the containment isolation status display and the SPDS station. Restrictions will be added to the applicable plant drawings in order to prevent any change in the existing visual access.
OdWN Concern:
"The SPDS is reliable. However, the licensee should evaluate the need to develop more sophisticated data validity algorithms for single input parameters."
Response: This concern is currently being evaluated. If useful algorithms can be developed using existing inputs, they will be incorporated into the SPDS design.
Item 6 This item concerns the human factors engineering principles which were adequately incorporated into the original SPDS design, with several minor exceptions.
Each exception is addressed below.
a.
" Source range power during power operations indicates a value reading."
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There is no obvious explanation for this intermittent occurrence.
The physical source range channel circuitry will be reviewed and troubleshot during the refueling outage this spring.
If the problem cannot be corrected during the refueling, the nuclear instrumentation channels are scheduled for replacement during the 1988 refueling outage and this should correct the problem, b.
" Cyan color used for parameter valves has low contrast to the white used for invalid data coding."
The blue background color of the alert indicator boxes will be substituted on all displays which currently use cyan.
Since the alert indicator boxes are segregated from the lower level process displays, the use of blue should not cause any confusion.
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c.
" Red indicator lights on SPDS panels serve no function."
The red lights are above the special function keys associated with each-SPDS displays. The lights were part of the standard equipment.
configuration supplied by the cathode ray tube (CRT) manufacturer. The lights are never lit and, therefore, they will be covered to remove them
-from the operators' view.
d.
"There is no audible alarm signal associated with SPDS alcrts."
This design feature, no audible alarm, was done in an effort to minimize the audible tones in the Control Room which could possibly cause confusion. After gaining some operational experience with the SPDS, an intermittent' audible alarm seems warranted. Each SPDS panel (keyboard) has in internal electronic beeper. This beeper will be pulsed each time an alert indicator box alarms.
This intermittent alarm will make the operator aware of the SPDS and its alarm condition but will not distract' him from performing actions which he may deem to be more significant in nature.
. e.
"The licensee has not provided the NRC with a written response to.the DCRDR HEDs related to SPDS."
The findings associated with the SPDS were separated into four MgDs.
These findings are addressed below:
e.l.
HED'0800, Finding 0800; "Some glare (on CRT screens) from fluorescent lights."
This particular finding concerned glare c'. T.,rallax problems associated with the various Control Room instruments. The SPDS CRT displays are included in this HED because of glare.
The fluorescent lights in the Control Room are part of the original plant deaign. Experiments will be performed during the next refueling'to monitor the effect of replacing the original curved glass lenses of the light fixtures with flat lenses. This finding is incorporated into the environmental study of the Control Room associated with the CRDR program, e.2.
HED 1000, Finding 0337; " Radiation not included among upper level displays on SPDS but it can be called up."
When the CRDR was performed, the Yankee SPDS terminology categorized displays into upper and lower level displays. The upper level displays consist of the Steam Generator Summary Display, the Pressure Versus Temperature Plot, and the Custom Trend Plot.
The lower level displays monitor the five (5) critical safety functions (CSF). The CSFs for the-Yankee plant SPDS are Reactivity Control, Main Coolant Inventory, Core Heat Removal, Secondary Cooling and Inventory, and Vapor Container Integrity. The input paraneters to 3
the five CSFs are constantly being scanned for comparison to I l' a i s
e predetermined alarm setpoints. Radiation parameters are inputs to the Secondary Cooling and Inventory, Vepor Container Integrity, and Main Coolant Inventory CSF displays.
Since the radiation inputs are constantly scanned for comparison to alarm setpoints and the results of the comparison are readily available to the operator in the form of the alert ~ indicator boxes (blinking when an alarm condition occurs), no change to the existing design is warranted. This finding is considered resolved.
e.3.
HED 1000, Finding 340; " Power and some other variables are sampled every four seconds instead of recommended'two seconds."
The recommendation for two-second samplings (scan frequency) is derived from NUREG-0835.
The scan frequencies, for-the process parameters which can change rapidly, have been selected to be frequent, with samples as follows: nuclear instrumentation inputs (source, intermediate and power range) - two. seconds; pressurizer level - two seconds; main-coolant. pressure -:two seconds; hot and cold leg temneratures (rosistance temperature detectors) - four seconds; and steam
. generator level - two seconds.
As can.be seen from the above examples, the scan frequency has been.
selected to match the expected change in the process and its method of measurement at the Yankee plant. This finding is considered resolved.
e.4.
HED 1000, Finding 338; "Where multi-measurements of same point do not compare, or if out of range shows up white - this does not work in shutdown.
Finding 338 discusses a parameter validation technique used on the Yankee plant SPDS.
The parameter trace and digital values will be displayed, even during plant shutdown, in white when a parameter is out of its designated range, or when out of tolerance with other inputs of the same process variable. However, during shutdown when level values may be high and pressure values low, the SPDS displays may show white. Since the typical instrument loop signal is 4-20 milliamperes (mA), when a pressure input goes to O psig (4 mA), the SPDS will still show a valid signal since O psig is the bottom of the range.
If a level goes high during shutdown, and the process input exceeds 20 mA (a function of level instrument tap location and instrument design), the variable will be displayed as white on the SPDS since it is out of range.
As discussed above, this finding is considered resolved.
e.5.
HED 1000, Finding 347, "No standard reliability test for operator to perform."
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.c This finding implies'two things. First, that a reliability test is necessary'and, second, that the operator should perform the test.
Since the CRDR was performed, a Software Monitor Program has been implemented on the SPDS.
This program monitors the performance of
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the data collection, data archival, and data display functions of
.the SPDS. When an error is detected, the SPDS is automatically
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flushed and the displays go blank. The SPDS must then be rebooted (restarted). The historical data is retained in memory up to the time when the malfunction occurred. This finding is considered resolved.
e.6.
HED 1000, Finding 348; "No indication of failure. Only failure to respond to operators command." See Item e.5 above. This finding is considered resolved.
e.7.
HgD 1000, Finding 341; " Display is not specialized to operating mode."
The SPDS at the Yankee plant, since its initial conception, has been designed to reflect the plant conditions at full power operation.
The SPDS was not designed to recognize changes in parameters due to changes in plant operating modes.
During refueling, the SPDS is
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used typically for trending. This finding is considered resolved.
I e.8.
HED 1000, Finding 346, "The alarm clears by itself. This is different from all other control Room alarms."
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.The SPDS alarm philosophy is that the alarm setpoints supplement the i
Control Room annunciator alarms. The SPDS alarms _are either higher, lower, or dif ferent (i.e., trajectories) in numerical value than the
-annunciators. Since the primary user of the SPDS'is expected to be the Shift Supervisor and other~ Control Room personnel at their option, during a very busy time, the resetting of an alarm condition
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would be a definite nuisance. The alarm cleared condition is evident by the displayed digital valve returning to its normal process color and the alert indicator box returning to solid blue, rather than magenta. The peak in the process variable will remain on the display for 30 minutes, similar to an inking recorder. When an alarm is cleared, it means the critical safety function is no longer being challenged. Based on the above, this finding is considered resolved.
e.9.
HED 1001, Finding 345; "No audible alarm." Refer to Item 6.d above. This finding is considered resolved.
e.10.
HED 1001, Finding 339; "No color or other means to indicate approach to unsafe condition except saturation margin."
Refer to Item e.8 above.
Since the SPDS alarms supplement the l
annunciator alarms, any additional approach to unsafe condition alarms or color changer would overly complicate'to SPDS design and l'~
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i displays. The purpose of the SPDS itself is to indicate an approach
.to an unsafe condition, i.e., a critical safety function is being challenged. Based on the above, this finding is considered resolved, e.11.
HED 1002, Finding 351; "Two hours of training on SPDS-is all operators have had."
HED 1002, Finding 396, "The SPDS does not adequately identify emergency by sequence of alanns. NOTE: This can be due to lack of I
training also."
HED 1002, Finding 385; "The SPDS has not been a convenient useful-tool for the operator.
It is inaccurate, frequently unavailable, controlled from elsewhere. Not well understood by the operator."
t Finding 351 concerns the formal classroom training provided during the initial: installation of the SPDS. The training covered the purpose, operation, and various functions of the SPDS.
This allowed the operators' time to manipulate, monitor, study, and learn about 4
the SPDS.
Findings 396 and 385 resulted from the operator interview portions I
of the CRDR. The interviews were performed approximately July 1984.
A problem listing was developed and used to track all hardware and software problems, both big and small. This allowed the system designers to receive feedback from the plant operators. The problem i-listing worked well and all reported problems were' corrected.
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The concern about identifying the emergency by a given sequence of alarms was not the intent of the system design..The SPDS displays were developed around the critical safety functions, refer to Item
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e.2 above.
The symptom-based emergency operating procedures, to be implemented, j
are also based on the critical safety functions. The operators are i
currently undergoing training on the new procedures.
The relationships between the new procedures and the SPDS are being reviewed with the plant operators.
Based on'the above, these findings are considered resolved,
,l-CONCLUSION The changes to the SPDS, committed to above, will be implemented during the next two refuelings. This will allow time for adequate software development, ve' ification, and validation prior to implementation.
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