ML20104B388
| ML20104B388 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 09/10/1992 |
| From: | William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20104B391 | List: |
| References | |
| TXX-92416, NUDOCS 9209150302 | |
| Download: ML20104B388 (13) | |
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b Log # TXX-92416 File # 916
_ ._7. 10010 r r Ref. # 10CFR50.90 TURECTRIC 10CFR50.36 sept enibe r 10. 1992 William J. Cahill, Jr.
Gwe % finident U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 d
SUBJECT:
COMANCHE PEAK STEAM ELECTRif STATION (CPSES)- 'JNIT 1 DOCKE1 NOS. 50-445 g
$UBMITTAL OF LICENSE AMENDMENT REQUEST 92-04 UNDERVOLTAGE AND UNDERFREQUENCY CHANGES TO TABLE 2.2-1 0F THE UNIT 1 TECHhlCAL SPECIFICATIONS Gentlemen:
Pursuant to 10CFR50.90, TU Electric hereby requests an amendment to the CASES Unit 1 Operatitio License (NFP-87) by incorporating the enclosed changes into the CPSES Unit 1 Technical Specifications.
In general, the proposed changes revise the CPSES Unit 1 Technical Specifications by changing the 'Z" value of Table 2.2-1 for the Undervoltage (UV) relay and by changing the allowable value of Table 2.2-1 for the Underfrequency ('JF) relay. These changes are required to incorporate a previously unaccounted for uncertainty in the UV relay setpoint calculations and to provide relief to maintenance personnel in setting the UF setpoint.
Attachment 2 provides a detailed description of the proposed change, the basis for the change, a safety analysis of the change, and TV Electric's determination that the proposed change does not involve a sigr.ificant hazards consideration. Attachment 3 provides the affected Technical Specification pages (NUREG-1399), marked up to reflect the proposed change.
Attachment 4 provides a copy of TV Electric Reactor Engineering Calculation- *RXE-TA-CP1/0-027 Rev. 1.*
The analysis performed to support the proposed change demonstrates that neither the change in "Z' value for the Undervoltage relay or the requested change in " Allowable Value' for the Underfrequency relay are a safety concern, and that CPSES Unit 1 is in full compliance with regulations.
TU Electric requests that the approval transmittal for this proposed amendment include a 30 day implementation period f ollowing the date of issuance.
. t.^.045 9209150302 920910 gDR ADOCKOSOOg5 h6f l
TXX 92416 Page 2 of 2 In accordance with 10CFF.50.91(b), TO Clectric is providing the State of Texas with a copy of this proposed amendment.
Should you have and questions, please contact Mr. Jose' D. Rodriguez at (214) 812-8674.
Sincerely.
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- _ v William J. Cahill . dr.
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Attachments: 1. Affidavit
- 2. Description und Assessment
- 3. Affected Technical Specification pages (NUREG-1399)
- 4. RXE-TA-CP1/0 027 Rev. 1 c- Mr. J. L. Milhoan, Region IV tir. B. E. Hollan. NRR Mr. T. A. Bergman, NRR Resident inspectors, CPSES (2)
Mr. D. K. Lacier Bureau of Radiation Control Texas Department of Public Health 1100 West 49th Street Austin, Texas 78704 l
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Attachment to TXX-92416 Page 1 of 1 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION in the Hatter of )
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Texas Utilities Electric Company ) Doctet Nos. 50 445
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(Comanche Peak Stean Electric ) License No. NFP 87 Station, Unit i 1 )
A F F I(1 ART, William J. Cahill, Jr. being duly sworn, hereby deposes and says that he is Group Vice President. Nuclear of TU Electric, the lead Applicant herein: '
that he is duly authorized to sign and file with the Nuclear Regulatory Commission License Amendment Request 92-04 'Undervoltage and Underfrequency a
Changes to Table 2.2-1 of the CPSES UM T 1 Technical Specifications *: that he is familiar with the content thereof; and that the mitters set forth therein are true and correct to the best of his knowledge, information and belief.
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j William J. Cahiil, Jr.
Group Vice Presideat, Nuclear STATE OF TEXAS )
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COUNTY OF SOMERVELl, )
Subscribed and sworn to bef ore me, on this _10tiiay t of September,1992. i 7
_ -_! . U otary Public
! A FATRICIA WILSON ilf h h urun n tw w e.a
\.:lLg.:/ thtc1 10,1993
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{ Attachment 2 to TXX 92416 4 Page 1 of 10 j DESCRIPTION AND ASS Q1tiMI L
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j EACKGROUND Protection for a total loss of flow in the Reactor Coolant System-(RCS) is ,
j provided by Reactor Coolant Pump (RCP) Bus undervoltage (UV) and j underfrequency (UF) reactor tvips. The RCP voltage and frequency are j monitored by UV and UF relays connected at the pump side of the RCP breakers.
l The nominal UV and UF trip points are set at 80.5 V and 57.2 Hz. The relay
- settings correspond to a bus _ voltage and frequency of 4830 y and 57.2 Hz. The f baris and methodology for calculating the setpoints are found.in Westinghouse l document WCAP-12123 . Rev.1;
- Westinghouse -Setpoint Methodology for 1
j Protection Systems Comanche Peak Unit 1.* The bus _UV and UF trip points are j listed in the Unit 1 Technical Specifications Table 2.2.1. in station document l El-2400: " Protective Devices Settings Document." and in station document El-
{_ 2700: ' Precautions Limitations and Setpoint Document."
)
i j A review and comparison of documents' uncovered a discrepancy in the adjustment-j telerances allowed for the UV and UF relays. The calibration allowances in 4
- 1. WCAP-12123 are given as +/- 1.4 % of span for the UV relay and +/ 0.7 % of span for the UF relay.# The calibration allowances translated to equivalent l relay adjustment tolerances of 80.08 V to 80.92 V for the UV' relay land 57.17 -
p Hz to 57.23 Hz for the UF relay. The specified relay adjustment tolerances _in 4
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i WCAP-12123 was transmitted to the NRC as an enclosure to TV Electric
- l. Letter logged TXX 89205 from William J, Cahill, Jr.-to NRC dated May-10, 1989.
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i 'WCAP 12123 assumes a Rack. Calibration __ Accuracy'of 0.7 % of span, a Rack i
Measuring and Test Equipment Accurecy of 0,7 % of span, and a Rack Drif t of 0.7 % of span in-calculating the Channel Statistical Allowance for the UF relay. -The Reactor Engineering Calculation; *RXE*TA-CP1/0 027.-
Rev. l' assumes a Rack Calibration Accuracy of 1.0 % of span, a Rack-
_ Measuring and Test Equipment Accuracy of 0.34 % of span, and!a. Rack.
Drif t.of 0.67-% of span in_ calculating the Channel Statistical' Allowance i for the UF relay. -Both documents-calculate the Channel Statistical
, Allowance at 2.1 % of span. The Reactor Engineering calculation allows
- a larger UF relay calibration allowance by limiti,.J the amount of drift allowed and requiring. greater accuracy (4:1) in the Measuring and Test i Equipment.
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Attachment 2 to TXX-92416 Page 2 of 10 DESCRIPTION AN'J ASSESSNENT station document El-2400 were given as 79.29 Y to 81.70 V for the UV and 57.1 Hz to 57.31 Hz for the UF relays. The El 2400 relay adjustment tolerances translated to calibration tolerances of +/ 4 % of span for the UV and
+/- 2.22 % of span f or the UF relays. The tolerances in WCAP 12123 were used by Westinghouse in determining the values of Table 2.2.1 of the Technical Specifications. A review of surveillance records for the UV and UF trip functions revealed that all 'as f ound* values and the latest 'as lef t' value were within the more restrictive WCAP 12123 tolerances. El 2400 was revised to agree with the WCAP 12123. The review of document. tion to resolve the differences in toleraates showed that the potential transformer, which reduces bus voltage for monitoring, had an uncertainty of- 0.3 % that had not been considered in the original setpoint study.
During the review, maintenance personnel stated-that adjusting the UF relay within such a narrow tolerance was difficult. The UF relay is an integral part of the rack, and any relaxation of the tolerance would be reflected on
..e Rack Calibretion Accuracy (RCA) term used in the setpoint methodology, Descriotion of Technical Specification Chance Reay111 3 This amendment proposes to change CPSES Unit 1 Technical Specification Table 2.2.1 F* actor Trip System Instrumentation Trip Setpoints,' item 14
'Undervoltage: Reactor Coolant Pump
- and item 15 'Underfrequency: Reactor Coolant Pump.' The proposed amendment to the Technical Specifications will change the 'Z' value in Table 2.2.1 for the Undervoltage Relay (item 14) from the current 0.0 % to 1.2 % of span. The proposed amendment will also change the ' Allowable Value' entry in Table 2.2.1 for.the Underfrequency Relay (item
- 15) from the current 57.1 Hz to 57,06 Hz.
3 The UV relay senses ACP Bus voltage through.a potential transformer. The potential transformer has a primary to-secondary winding ratio of 60t1 (7200V:120V) with an-uncertainty of--0.3 %. The primary to secondary winding ratio ~ and the associated uncertainty translates to an output voltage, with a 7.2 KV input. of 120 V +/- 0.36 V or +/" 1.2 % of span. Incorporating the potential transformer uncertainty changes the Primary Element Accuracy (PEA) of the Westinghouse Setpoint Methodology from 0,0-% to 1.2 % span. The 'Z'
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s Attachment 2 to TXX-92416 ;
Page 3 of 10 t DESCRIPTION A@__AMIME value of Table 2.2.1 of the Technical Specifications is defined in the BASES of the Technical Specifications as being the statistical sum' of the errors ,
i assumed in the analysis excluding those associated with the-sensor and rack l
, drift as well as the accuracy of their measurement. WCAP 12123 calculates the 1
'Z' value as the sum of the sensor environmental allowance plus the SRSS of ;
l 1 the piocess measurement accuracy, the primary element accuracy, the sensor f temperature effects, the sensor pressure effects, and the rack temperature l effects (ste figure 1). The *2' term in Table 2.2.1-of the Technical !
- Specifications for item 14 is changed from 0 %_to 1.2 % of_ span. The Channel 5
Statistical Allowance (CSA) for the UV trip, which uses the same terms as the 4 '
Z' term. also changes. The changed CSA is sti11 below the Total Allowance of
] 7.7 % of span which is listea in Table 2.2.1. -
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- The Of relcy monitors the RCP bus frequency and provides_ backup protection to _
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- the UV trip on a complete loss of flow. Westinghouse, in WCAP-12123 assumes that the Or relay is an integral part of the instrument rack and treats the' uncertainties as part of the rack uncertainties. Relaxing the UF relay adjustment tolerance from 1 % to 2.% of span will change the various terms used in determining the Channel Statistical Allowance (see figure 2). from the attached TV Electric Reactor Engineering Calculation: 'RXE TA CP1/0 027 .
Rev.1.* relaxing the. relay adjustment tolerance changes the Rack-Calibration '
Accuracy (RCA) from 1 %_to 2 %. the Rack Measuring and Test EquipmentL(RMTE) _ :
allowance-from 0,34 % to 0.5 %, and the Channel Statistical Allowance (CSA)
- from 2.01 % to 3.17 %. The Allowable Value d of Table 2.2.1 of the Technical l ' Westinghouse uses the square root of the sum-of the squares (SRSS) as ;
the basic methodology for_ calculating the loop uncertainty associated with the _ various component variables.
'WCAP 12123 discusses the " Allowable Value' and the trigger' values that
-are used.in its-calculation. The first trigger value T1.-is the arithmetic sum of the instrument loop. uncertainties _ encountered during calibration plus:the nominal safety. system'setpoint, 'The second T2. is >
' the difference between the SRSS of the uncertainties for which there is no periodic survelliance plus the-square of the sum-of the sensor parameters and the Safety: Analysis Limit. The Allowable' Value. is the more conservative result of'the abcve calculations.-.Forithe
- underf requency allowable value. T1 dominates and is -used in the -
calculation.
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Attachment 2 to TXX 92416 Page 4 of 10 l
DESCRIPTION AND ASSE1L1N1 specifications is defined in WCAP 12123 as the nominal setpoint plus the arithmetic sum of the instrument uncertainties (ie., rack drif t. rack temperature effects, measuring and test equipment allowance, and the rack calibration accuracy). The change in UF relay tolerance from 1 % to 2 % of span results in an Allowable Value change to Table 2.2.1 of the Technical Specifications for item 15 from 57.1 Hz to 57,06 Hz. Although the Allowable Value for the UF relay is closer to the Nominal setpoint assumed in the accident analysis and the CSA increases from 2.01 % to 3.17 % of span, the Total Allowance (TA)', at 4.4 % of span, is still greater than the CSA.
In summary,_the addition of the potential transformer unce,tainty into the UV relay calcelations changes the *Z' value listed in Table 2.2.1_ of the Technical Specifications for item 14 from 0.0 to 1.2 % of span. Relaxing _the tolerance for the UF relays f rom 1 % to 2 % of span changes the ' Allowable Value' column of able 2.2.1 of the Technical Specifications for item 15 from 57.1 Hz to 57.06 Hz.
AMLY111 The amendment request proposes to change the *2' _value of Table 2.2.1 of the Technical Specifications for the UV relay from the current 0.0 % to 1.2 % of span, and to change the " Allowable Value" of Table 2.2.1 of the Technical ;
Specifications for the UF relay from the current 571 Hz to 57.06 Hz. The changes are necessary to incorporate a_ previously overlooked uncertainty-of 0.3 % for the UV relay 'entialitransformer and to provide relief to maintenance personnel who are having a. difficult time setting the UF relay-within'the present calibration tolerance of '+/ 1 %-by- relaxing the.
calibration. tolerances to +/ 2 % of. span.
The relays monitor the RCP electrical supply, downstream of the breaker on the -
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pump side. -In assessing the safety impact of the proposed amendment-on the plant, various documents were reviewed: the Reactor- Engineering- Calculation-
"RXE-TA-CP1/0 027 Rev.1:* El-2700: ' Precautions Limitations and Setpoint Document:'_WCAP-12123 Rev. 1; ' Westinghouse Setpoint. Methodology-for Protection Systems Comanche Peak Unit'_l " El 2400:
- Protective Devices Total Allowance is ' defined in the Technical Specification BASES 'as-the difference between the. Safety Analysis Limit _and the Nominal Setpoint-,
both of which are unchanged.
Attachment 2 to TXX-92416 Page 5 of 10 DESCRIPTION AND ASSESSMENT Settings Document:* the BASES section of the Technical Specification: and FSAR Section 15.3.2. ' Complete loss of Forced Reactor Coolant Flow.' The review concluded that the proposed changes to the Technical Specifications do not change the operating setpoints or any other operating parameters of the relays nor do they introduce any physical changes to UV/UF monitoring circuits. The proposed change introduces no credible potential failures into the RCS or '
Electrical Distribution System.
The review of Section 15.3.2 of tl FSAR shows that the nominal setpoint assumed in the accident analysis for the UF trip point of 57.0 Hz is not changed by this amendment request, thus the accident analysis is not affected.
Since the assumptions and results of the analysis of a ' Complete loss of Reactor Coolant Flow' are-unchanged, the radiological consequences and the probability of occurrence remain unchanged. The proposed changes affect only the assumed uncertainties of the UV-and UF monitoring relays. Because there are no physical or setpoint changes to the relays and because there are no credible failure modes or malfunctions introduced into the systems they monitor, the possibility of a new and unanalyzed type of event is unchanged.
The margin of safety remains unaffected because neither the nominal setpoint nor the assumptions used in the accident analysis are changed.
In summary, this change does not constitute an unreviewed safety question but it does involve a change to the technical specifications which are an attachment to the operating license.
Sionificant Hazards Consideration Determination (1) Does the proposed revision involve a significant increase in the probability or consequences of an accident previously evaluated in the Safety Analyses Report?
As stated above, the proposed change to Table 2.2.1 of the Technical Specifications does not involve an increase in the probability of an accident previously evaluated in the Safety Analyses Report.
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Attachment 2 to TXX 92416 Page 6 of 10 DESCRIPTION AND ASSESSMENT El The accident analysis of FSAR Section 15.3.2:
- Complete Loss of forced Reactor Coolant Flow
- is not impacted by the change in 'Z' value for the UV trip. The change in 'Z' value for the UV relay does not change the operating setpoints or any other operating parameters of the relays. The change does not introduce any physical changes to UV monitoring circuits, thus there are no-new credible potential failures that can be introduced into the RCS or Electrical Distribution System. The change does not introduce failures which result in a decrease-in Reactor Coolant Flow. The change does not alter the probability of occurrence of a complete loss of forced reactor coolant flow.
The change does not alter the time sequence of events for incidents which result in a decrease in Reactor Coolant system flow rates of Tab'ee 15.3.1, nor does it alter the transient curves of-Figure-15.3.:2-A and 15.3.9-A. The change does not alter the consequences of a complet( loss of forced reactor coolant flow.
ME The accident analysis, of FSAR Section 15.3.2: " Complete Loss of Forced Reactor Coolant Flow" states that the UF trip serves.as a backup for the UV trip.
The change does not introduce any physical changes to UV monitoring circuits, thus there are no credible potential failures that can be introduced into the RCS or Electrical Distribution System. .The change to the Allowable Value will not result in a decrease in Reactor coolant flow. The change does not alter the probability of a Complete loss 6f Forced Reactor Coolant Flow from occurring. This request proposes to change the Allowable Value for the-UF trip. The actual trie point would still be more conservative than the 57.0 Hz which is mentioned-in section 15.3.2 of the FSAR. The accident analysis does not use the UF trip in the transient analysis for a. Complete Loss of Forced Reactor Coolant Flow. The change to the Allowable value does not alter.
the time sequence of everts of Table 15.3.1, nor does it alter the transient curves of Figure 15.3.12-A and 15.3.9-A. The change does not alter the consequences of a complete loss of_ forced reactor coolant flow.
(2) Does the proposed revision create the pos~ 'ility of a new or different-kind of accident from any previt. ,1y analyzed?
Attachment 2 to TXX-92416 Page 7 of 10 DESCRIPTION AND ASSESSMENT The proposed changes to the UV and UF trip data of Table 2. 2.1 of the Technical Specifications do not introduce any credible failure or accident modes into the RCS. the RCP, or Electrical distribution systems. The proposed changes do not create the possibility of a new or different type of accidents not previously analyzed.
(3) Does the proposed revision involve a significant reduction in the margin of safety?
The margin of safety is defined as the dif ference between a regulated acceptance criterion and the failure point for a particular parameter.
Neither the UV or UF trip data changes affect the assumptions or results of the safety analysis. The conclusions of the safety analysis are not affected by the proposed changes. The proposed changes-do not impact any failure points ' the RCS, RCP. or Electrical Distribution System. The Margin of Safety is not reduced.
In conclusion, the proposed technical specification changes to the CPSES Unit _ Technical Specification Table 2.2.1, " Reactor Trip System Instrumentation Trip Setpoints," item 14 'Undervoltage: Reactor Coolant Pump' and item 15 'Underfrequency: Reactor Coolant Pump
- do not involve a significant hazard consideration.
ENVIRONMENTAL EVALUATION 10 CFR 51.22(b) specifies the criteria for categorical exclusions f rom 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).
Specific criteria contained in this section.are discussed below.
(i) the' amendment-involves no significant' hazards consideration As demonstrated in the Significant Hazards Consideration Determination the requested license amendment does not involve any significant hazards considerations.
(ii) there isLno significant change in the types or significant increase in the amounts of any effluents that may be released offsite.
Attachment 2 to TXX-92416 Page 8 of 10 DESCRIPTION f3D ASSESSMENT The requested license amendment involves no change to the f acility and does not alter the manner of operation of the relays in a way which could cause an increase in the amounts of ef fluents or create new types of effluents.
(iii) there is no significant increase in individual or cumulative occupational radiation exposure The proposed changes do not impact plant design features or operations that affect radiation protection, radioactive effluent processing, radioactive =
waste handling, or radiological environmental monitoring.- The changes do not result in additional exposure by personnel ner' af fect levels of radiation present. The proposed changes do.not result in significant individual or cumulative occupational radiation exposure.
Based on the above, it is_ concluded that there will be no impact on the environment resulting f rom this change and the change meets the criteria specified in 10 CFR 51.22 for a categorical exclusion f rom the requirements of 10 CFR 51.21 relative to a specific environmental impact statement or environmental assessment by the Commission.
BEFERENC(1 El 2700: ' Precautions Limitations and Setpoint Document -
-WCAP-12123 Rev. 1;" Westinghouse Setpoint Methodology for Protection Systems Comanche Peak Unit 1.*
f El 2400; ' Protective Devices Settings Document.'
Reactor Engineering Calculation: 'RXE-TA-CP1/0-027 Rev. 1.*
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FSAR Section 15.3.2; " Complete loss of Forced Reactor Coolant Flow.'
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Attachment 2 to TXX-92416
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.' UNDERVOLTAGE S
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! % Span Parameter Eng Units j Old [New]
! ,r=p===p================= Nominal Setpoint --- -
4830V j Env Allowance
! Rack Temp Effects
! Sensor Temp Effects i Z= 0% Sensor Pres Effects i [1.2%) Process Measurement Accuracy-Primary Element Accuracy 1 138V=7.7% e 4 .1.................................................... .
of j 1800V span j Rack Drift
.; Rack M&TE i Rack Cal Accuracy j CSA = 4.3 % Rack Comparator Setting Accuracy ;
(4.45 %) Sensor Drift
, -Sensor Cal Accuracy -
3 Sensor M&TE I
- .. ..u....................,..........................................
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! Total = 7.7-% Margin.
Allowance [7.7 %]
'. =4========================= Safety Analysis Limit 4692V i
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! Attacment 2 to TXX- 416 j Page 10 of 10 1
i UNDERFREQUENCY i
l- Nominal Setpoint - -
57.2 Hz -
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1 l Curre.it Allowed Value - -
57.1 Hz 1
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/ Proposed Allowed Value - -
57.06 Hz 4.4 % of l 4.5 Hz span 1
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j Assumed Safety Analysis - -
57.0 Hz - ,
- i. Point. '
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