ML20209D356
| ML20209D356 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 07/08/1999 |
| From: | Muench R WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20209D361 | List: |
| References | |
| ET-99-0029, ET-99-29, NUDOCS 9907130115 | |
| Download: ML20209D356 (11) | |
Text
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W4)NUCLEAROPERATING C LF CREEK Richard A. Muench Vice President Engineenng ET 99-0029 l
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U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station Pl-137 Washington, D. C. 20555
Subject:
Docket No. 50-482: Proposed Revision to Technical Specification Table 3.3-4, Functional Unit 8, Loss of Power I
Gentlemen:
This letter transmits an application for amendment to Facility Operating License No. NPF-42 for the Wolf Creek Generating Station (WCGS).
This request proposes to revise the Allowable Value for current Technical Specification Table 3.3-4, Functional Unit 8.a.,
4 kV Undervoltage - Loss of Voltage and Functional Unit 8.u.,
4 kV Undervoltage - Grid Degraded Voltage.
A safety evaluation is provided in Attachment I.
A No Significant Hazards I
Consideration Determination is provided in Attachment II.
Attachment III is the related Environmental Impact Determination.
Marked up pages are provided j
in Attachment IV (for current Technical Specifications and Bases) and in Attachment V (for improved Technical Specifications and Bases as approved by l
Amendment No.
123).
The proposed changes to the improved Technical 3
l Specification Bases are provided for information.
Attachment-VI provides a i
listing of commitments made in this submittal.
In accordance with 10 CFR 50.91, a copy of this application, with attachments, l
is being provided to the designated Kansas State Official.
This proposed l-revision to the WCGS current Technical Specifications will be fully implemented within 60 days of formal NRC approval.
If you have any questions concerning this matter, please contact me at (316) 364-4034, or Mr. Michael J. Angus, at (316) 364-4077.
Very truly yours,
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9907130115 990700 PDR ADOCK 05000482 g
P PDR Richar A. Muench l
RAM /rir Attachments:
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- Safety Evaluation II
- No Significant Hazards Consideration Determination III - Environmental Impact Determination
. O IV
- Proposed Current Technical Specification Change V
- Proposed Improved Technical Specification Change VI
- List of Commitments cc:
V.
L. Cooper (KDHE), w/a J. N. Donohew (NRC), w/a W.
D. Johnson (NRC), w/a E. W. Merschoff (NRC), w/a eniorResMenhO o'[4Nu5hnhok.kT 66N[fi Phone: (316) 364-8831 An Equal Opportundy Employer M F'HC' VET
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l STATE OF KANSAS
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SS COUNTY OF COFFEY
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Richard A. Muench, of lawful age, being first duly sworn upon oath says that he is Vice President Engineering of Wolf Creek Nuclear Operating Corporation; that he has read the foregoing document and knows the content thereof; that he has executed that same for and on behalf of said Corporation with full power and authority to do so; and that the facts therein stated are true and j
correct to the best of his knowledge, information and belief.
1 By
/MM Richard 4.' Muench Vice Pr sident Engineering
)b day of 1
, 1999.
SUBSCRIBED and sworn to before me this O
CNWHOVN WI Notary g lic
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w w wuom Expiration Date ROM i
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Attachment I to ET 99-0029 Page 1 of 4 L
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1 ATTACHMENT I l
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SAFETY EVALUATION l
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l Attachment I to ET 99-0029 l
Page 2 of 4 l
Safety Evaluation Proposed Changen, l
This license amendment request proposes to revise Allowable Value for the Wolf Creek Generating Station (WCGS) current Technical Specifications Table 3.3-4, Functional Unit 8.a.,
4 kV Undervoltage - Loss of Voltage, and Functional Unit 1
8.b.,
4 kV Undervoltage - Grid Degraded Voltage.
The associated changes to the improved Technical Specifications, as approved by Amendment No. 123, are provided in Attachment V.
The proposed revision incorporates new values based on revised load flow and voltage drop calculations.
Specifically, the amendment request proposes changing Technical Specification Table 3.3-4, Functional Unit 8.a and 8.b. to the below Allowable Value:
ALLOWABLE i
VALUE 8.
Loss of Power a.
-Loss of Voltag,e 2 82.5V (120V Bus) w/1
+0.2,
-0.5s delay b.
-Grid Degraded Voltage 2 105.9V (120V Bus) w/119 1 11.6s delay
Background
The emergency diesel generators (EDGs) provide a source of emergency power
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when offsite power is either unavailable or is insufficiently stable to allow l
safe unit operation.
If a loss of voltage occurs at the 4.16 kV Class 1E system (NB) bus (Engineered Safety Features (ESP) buses),
undervoltage protection will:
a) Trip the 4.16 kV preferred normal and alternate bus feeder breakers to remove the deficient power source to protect the Class 1E equipment from damage; i
b) Shed all loads from the bus except the Class 1E 480 Vac load centers and centrifugal charging pumps to prepare the buses for re-energization by the load shedder and emergency load sequencer (LSELS); and c) Generate a EDG start signal.
Upon detection of a degraded voltage condition, LSELS initiates a logic signal which serves only to trip the 4.16 kV Class 1E system (NB) bus normal and alternate feeder breakers.
The undervoltage relays then detect the resulting undervoltage condition and the same initiation signals as described above are actuated There are two sets of undervoltage protection circuits, one for each 4.16 kV Class IE system (NB) bus.
Each set consists of a loss of voltage and degraded voltage function.
Four potential transformers on each bus provide the necessary input voltages to the protective devices used to perform these functions.
The undervoltage protection circuits are described in the Updated Safety Analysis Report (USAR) Section 8.3.1.1.3.
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Attachment I to ET 99-0029 Page 3 of 4 Four undervoltage relays with an associa :ed time delay are provided for each 4.16 kV Class 1E system (NB) bus for detecting a loss of bus voltage.
The outputs are combined in a two-out-of-four logic to generate an undervultage l
signal if the voltage is below approximately 70% for 1 second (nominal delay).
Four degraded voltage bistables with associated time delays are provided for each 4.16 kV Class 1E system (NB) bus for detecting a sustained degraded voltage condition.
After LSELS timers expire, the four bistable outputs are combined in a two-out-of-four logic to generate a degraded voltage signal if l
the voltage is below approximately 90%.
If the degraded voltage condition is not alleviated within the overall time delay associated with the LSELS timers and feeder breaker time delay relays, the affected bus feeder breaker (s) is I
tripped.
The current Technical Specification 4 kV Undervoltage - Loss of Voltage Trip Setpoint is 2 83V (120V bus) w/1s delay with an Allowable Value of M 74.7V (120V Bus) w/1 +
.02,
-0.5s delay.
The current Technical Specification 4 kV l
Undervoltage - Grid Degraded Voltage Trip Setpoint is 2 106.9V (120V Bus) w/119s delay) with an Allowable Value of 2 105.9V (120V Bus) w/119 i 11.6s delay.
Conformance with the Technical Specifications is verified by performance of CHANNEL CALIBRATION and ANALOG CHANNEL OPERATIONAL TESTS.
If the as-found Trip Setpoint is within the calibration tolerance band, it is greater than the Allowable Value, the channel is considered OPERABLE, and no further action is required.
If the as-found Trip Setpoint is outside the calibration tolerance, but is greater than the Allowable Value, it is considered OPERABLE, but is recalibrated to within the calibration tolerance.
If the as-found Trip Setpoint is less than the Allowable Value, the channel is declared inoperable in accordance with current Technical Specification 3.3.2, Action b.
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Evaluation During a review of the electrical relay setting calculation (E-H-8),
WCNOC i
personnel identified that a revision to the load flow and voltage drop calculation (E-B-8) had resulted in revised worst case 4.16kV Class 1E system (NB) bus voltages that would be possible during steady state LOCA conditions.
i The revised worst case NB bus voltages are used as an input to the electrical relay setting calculation; however, this calculation had not been revised to reflect the new worst case NB bus voltages.
A calculation (Calculation No.
XX-E-009) was performed to establish the correct Allowable Value and Trip Setpoint for the loss of voltage and degraded grid voltage functions.
The results of this calculation are discussed below.
Loss of Voltage Four undervoltage relays with an associated time delay are provided for each l
4.16 kV Class 1E system (NB) bus for detecting a loss of bus voltage.
These i
relays are set below worst case steady state and transient conditions.
Since the undervoltage relays are sensing a complete loss of bus voltage, the relays are set at an arbitrary value of 70% of bus voltage (83V) at the relay (120V base).
The calculation determined that the Technical Specification Trip Setpoint of 2 63V remained the same.
The Allowable Value was calculated by taking into account instrument inaccuracies in the loop components using the Square Root of the Sum of the Squares methodology.
The instrument inaccuracies accounted for include:
j Potential Transformer Inaccuracies 0.30%
l Relay Error 1%
Attachment I to ET 99-0029 Page 4 of 4 9
4 An Allowable Value of 2 82.5V is calculated when accounting for these uncertainties.
l Grid Degraded Voltage The' grid degraded voltage Trip Setpoint is selected to ensure that no end use loads are adversely affected from sustained operation below the setpoint.
The Technical Specification Allowable Value is determined as follows:
NB Bus Grid Degraded Voltage aumane va2u.
(Minimum Bus Voltage / PT Ratio)
(3707 / (4200V / 120V)
=
= 105.9V The Trip Setpoint was calculated by taking into account instrument inaccuracies in the loop components using the Square Root of the Sum of the Squares methodology.
The instrument inaccuracies accounted for include:
Bistable Setting Accuracy 0.25%
Bistable Drift % Setting Effects 0.50%
Potential Transformer Inaccuracies 0.30%
A Trip Setpoint of 2 106.9V is calculated when accounting for these uncertainties.
Evaluation Conclusion The revised worst case 4.16 kV Class IE system (NB) bus voltages when input into the Loss of Voltage and Grid Degraded Voltage setpoint calculations, result in 1) no change to current Technical Specification Trip Setpoints, and
- 2) Allowable: Values for each function that are more restrictive than current Technical Specification values.
Therefore, administrative controls have been established to account for the non-censervative Technical Specification Allowable Value, as discussed in Administrative Letter 98-10, "Dispositioning of Technical Specifications That are Insufficient to Assure Plant Safety."
Impact to Improved Technical Specifications Amendment No. 123, dated March 23, 1999, converts the current WCGS Technical Specifications to the improved Technical Specifications. Attachment V to this letter provides proposed changes to the improved Technical Specifications (which are scheduled to be implemented by December 31, 1999).
Proposed changes to the Bases are provided for information.
Surveillance Requirement SR 3.3.5.3 is revised with the new Allowable Values and includes adding the i
word nominal to the Trip Setpoint.
In Section 3.3, the Trip Setpo
'.s are provided in the Technical Specification Bases and are considered nominal Trip Setpoints.
Since the Losc Of Power Diesel Generator Start Instrumentation specification includes the Trip Setpoints in the Technical Specifications, the word " nominal" is added to eliminate a literal compliance concern.
Conclusion.
The proposed changes impose a more restrictive Allowable Value than currently exists in the WCGS Technical Specifications.
These changes are consistent with.the revised calculation which includes worst case 4.16 kV Class lE system (NB) bus voltages that would be possible during steady state LOCA conditions and ensures OPERABILITY of the instrumentation critical for protection of the 4.16 kV Class lE system (NB) bus equipment.
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Attachment II to ET 99-0029 l
Page 1 of 3 l
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I ATTACHMENT II NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION I
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l Attachment II to ET 99-0029 Page 2 of 3 No Significant Hazards Consideration Determination 1
Proposed Changes This license. amendment request proposes to revise the Allowable Value for the Wolf Creek Generating Station (WCGS) current Technical Specifications Table 3.3-4, Functional Unit 8.a.,
4 kV. Undervoltage - Loss of Voltage, and Functional ' Unit, 8.b.,
4 kV Undervoltage - Grid Degraded Voltage.
The associated changes to the improved Technical Specifications, as approved by Amendment No.
123, are provided in Attachment V.
The proposed revision incorporates new values based on revised load flow and voltage drop calculations.
Specifically, the amendment request proposes changing Technical Specification Table'3.3-4, Functional Unit'8.a and 8.b. to the below Allowable Value:
l ALLOWABLE VALUE 8.
Loss'of Power a.
-Loss of Voltage 2 82.5V (120V Bus) w/l
+0.2,
-0.5s delay-b.
-Grid Degraded Voltage 2 105.9V (120V Bus) w/119 1 11.6s delay Application of Standards
'The following Standards identified in'10 CFR 50.92 have been used to determine whether the proposed changes involve. a Significant Hazards Consideration.
Each ' of _ the. identified prcposed changes is evaluated against the three Standards.
Standard I - Involve a Significant Increase in the Probability or Consequences of,an Accident'Previously Evaluated The protection system performance will remain within the bounds of the previously performed accident analysis.
The protection systems will continue to function in a manner consistent with the plant design basis.
The proposed changes will - not affect' any of the analysis assumptions for any of the accidents previously evaluated.
The proposed changes will not affect the probability of any event initiators nor will the proposed changes affect the ability ~ of any safety related equipment to perform its intended function.
There is no change'to the Technical Specification Trip Setpoints; therefore, there is no degradation in the performance of nor an increase in the number of challenges imposed on safety related equipment asstuned to function during an accident-situation and be no change ~ to normal plant operating parameters or accident mitigation capabilities.
- Based ' on : the. above evaluation, these changes do not involve a significant incra 4n the probability or consequences of an accident previously ev
- Attachment ~II to ET 99-0029 Page 3 of.3 Standard II - Create the Possibility of a New or Different Kind of Accident
.from any Previously Evaluated There are no changes in the method by which any safety related plant system performs its safety function.
The normal manner of plant operation remains unchanged since : there. is no change to the Trip Setpoints.
The increase in Allowable Valne still provides margin between the nominal Trip Setpoint and Allowable ~Value while taking into account worst case 4.16.kV Class lE system (NB) bus-voltages that.could be possible during steady state LOCA conditions The change.in Allowable Value does not impact the systems capability to:
a) Trip the 4.16 kV preferred normal and alternate bus feeder breakers to remove the deficient power source to protect the 1
Class lE equipment from damage; I
b).Shed all loads. from the bus except the Class lE 480 Vac load Leenters and centrifugal charging pumps to prepare the buses for re-energization by the load shedder and emergency load sequencer (LSELS); and c) Generate a EDG start signal.
No new accident scenarios, transient precursors, failure mechanisms, or limiting single failures are introduced as a result of the proposed changes.
Therefore, the _ proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.
Standard III - Involve a Significant Reduction in the Margin of Safety The undervoltage protection functions are to:
a) Trip the 4.16-kV preferred normal and alternate bus feeder breakers to remove the deficient power source to protect the Class lE equipment from damage; b)'Shed all loads from the bus except the Class lE 480 Vac load centers and centrifugal charging pumps to prepare the buses for re-energization by.the load shedder and emergency load sequencer (LSELS); and c') Generate a EDG start signal.
i The proposed changes do not affect _the acceptance criteria for any analyzed event nor is there.a. change in any Safety Analysis Limit.
There will be no effect on the manner in which safety limits or Engineered Safety Features
, Actuation Systemisettings are determined nor will there be any affect on those
' plant systems necessary.to. assure the accomplishment'of the above protection functions.
Therefore, will be.no impact on any margin of safety.
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1 Conclusions 3-Based on the' above4 discussions,- it has been determined that the requested
-technical specification rev.isions do not involve-a significant increase in the probability of consequences of an accident or other adverse conditions over
-previous evaluations; or create the possibility of a new or different kind of accident or condition over ' previous evaluations; or involve a significant
' reduction in a margin of safety.
'Therefore, the requested license amendment does not' involve a significant hazards consideration.
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Attachment III to ET 99-0029 Page 1 of 2 1
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ATTACHMENT III ENVIRONMENTAL IMPACT DETERMINATION
I-l Attachment III to ET 99-0029 Page'2 of 2
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Environmental Impact Determination This license amendment request proposes to revise the Allowable Value for the Wolf Creek Generating Station (WCGS) current Technical Specifications Table 3.3-4, Functional Unit.
8.a.,
4 kV Undervoltage - Loss of Vo3tage, and Functional. Unit 8.b.,. 4 kV Undervoltage.- Grid Degraded Voltage.
The associated changes to the improved Technical Specifications, as approved by Amendment No.
123, are provided in Attachment V.
The prcposed revision incorporates new values based on revised load flow and voltage drop calculations.
'Specifically, the amer.dment request proposes changing Technical Specification Table 3.3-4, Functional Unit 8.a and 8.b. to the below Allowable Value:
ALLOWABLE VALUE 8.
Loss of Power a.
-Loss of Voltage 2 82.5V (120V Bus) w/l
+0.2,
-0.5s delay b.
-Grid Degraded Voltage 2 105.9V (120V Bus) w/119 1 11.6s delay 10 CFR 51.22(b) specifies the criteria for categorical exclusions from the requirement for a specific environmental assessment per 10 CFR 51.21.
This amendment request meets the. criteria specified in 10 CFR 51. 22 (c) ( 9) as specified below:
(i) the amendment involves no significant hazards consideration As demonstrated in Attachment II, the proposed changes do not involve any significant hazards consideration.
(ii) there is no significant change in the types or significant increase in the amounts of any effluents that may be released offsite None of the proposed changes involves a change to the facility or operating procedures that would cause an increase in the amounts of effluents or create new' types'of effluents.
(iii) there is no significant increase in individual or cumulative occupational radiation exposure l
i The proposed change is administrative in nature and does require any changes to Trip Setpoints.
These changes-have no relation to occupational radiation exposure, either individual or cumulative.
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Based on the above, it is concluded that there will be no impact on the j
environment resulting from this change and the change meets the criteria i
specified in 10 CFR 51.22 for a categorical exclusion from the requirements of 10 CFR 51.21 relative to requiring a specific environmental assessment by the Commission.
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