ML20198P332
| ML20198P332 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 10/31/1997 |
| From: | Passwater A UNION ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20198P335 | List: |
| References | |
| ULNRC-3673, NUDOCS 9711070086 | |
| Download: ML20198P332 (13) | |
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U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station Pl-137 Washington, D.C. 20555 ULNRC-3673 Gentlemen:
DOCKET NUMPER 50-483 CALLAWAY PLANT CHANGES TO RTS AND ESFAS DELTA-T FUNCTIONAL UNITS
References:
- 1. ULNRC-3578 dated May 15,1991
- 2. ULNRC-2808 dated June 4,-1993
- 3. ULNRC-03198 dated April 17,1995
- 4. ULNRC-2196 dated April 12,1990
- 5. OL Amendment No. 84 dated November 8,1993
- 6. OL Amendment No.102 dated August 21,1995
- 7. OL Amendment No. 57 dated September 20,1990
- 8. ULNRC-03628 dated August 8,1997 Union Electric Company herewith transmits an application for amendment to Facility Operating License No. NPF 30 for the Callaway Plant.
This amendment application includes changes to Technical Specification Tables 2.2-1,4.3-1, and 3.3-4, as well as their associated Bases, in order to r
reduce repeated alanns, rod blocks, and partial reactor trips that continue to manifest themselves, especially during beginning of cycle operation following refueling outages. Besides the potential for distracting operator attention away from more safety significant evolutions, these occurrences have also led us to reduce power during surveillance testing in order to avoid reactor trips, since the channel being tested is placed in the tripped condition. These changes to various setpoint terms associated with the Overtemperature AT, Overpower AT, and SG Water Level Low-Low Vessel AT (Power-1 and Power-2) reactor trip and AFW start ESFAS functions will improve plant operations and reduce the potential for unnecessary reactor trips, with no detrimental effect on the plant's safety analysis or licensing basis.
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The Callaway Plant Onsite Review Committee and the Nuclear Safety Review Board have reviewed this amendment npplication. Attachments 1 through 3 provide the Significant Hazards Evaluation, Environmental i
Consideration, and proposed Technical Specification revisions, respectively, in suppon of this amendment request, In addition, Attachments 4 and 5 provide changes to Attachments 19 and 20 of the license amendment application submitted in Reference 1. It has been detennined that this amendment application does not involve a significant hazard consideration as detennined per 10CFR50.92. Pursuant to 10CFR51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
Reference 8 submitted a license amendment request to add a new ESFAS Functional Unit 5.d for Feedwater Isolation on SG Water Level low-Low.
This new Functional Unit includes the Vessel AT (Power-1 and Power-2) sub-units. The Trip Setpoints included in Reference 8 will be affected by the changes included herein. It is requested that the license amendment submitted in the attachments herewith be reviewed prior to the license amendment submitted in Reference 8 and that, when Reference 8 is reviewed thereafter, the Trip Setpoints for new ESFAS Functional Unit 5.d be modified consistent with the values included herein, i.e., Vessel AT (Power-1) at 12.41 % RTP and Vessel AT (Power-2) at 22.41 % RTP.
Approval of this amendment application is requested by April 15, 1998, to be immediately effective upon inuance and implemented within 30 days thereafter. This will support next spring's refueling outage, currently scheduled to begin on.A ail 1,1998. If you have any questions on this amendment t
application, please contact us.
Very truly yours,
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Alan C.
asswater Manager-Licensing and Fuels Attachments: 1 - Significant Hazards Evaluation 2 - Environmental Consideration 3 - Proposed Technical Specification Revisions 4 - Changes to ULNRC-3578 Attachment 19 5 - Changes to ULNRC-3578 Attachment 20
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s STATE OF MISSOURI )
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Alan C. Passwater, of lawful age, being first duly sworn upon oath says that he is Manager, Licensing and Fuels (Nuclear) for Union Electric Company; that he has read the foregoing document and knows the content thereof; that he has executed the same for and on behalf of said company with full power and authority to do so; and that the facts to the best of his therein stated are true and correct knowledge, information and belief.
GW By Alan C.
Passwater Manager, I.icensing and Fuels Nuclear SUBS IEED and sworn to before me this day of C7d'et 1997.
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M. H. Fletcher Professional Nuclear Consulting, Inc.
19041 Raines Drive Derwood, MD 20855-2432 Regional Administrator U.S. Nuclear Regulatory Commission 4
Region IV 611 Ryan Plaza Drive
-Suite 400 Arlington, TX 76011-8064 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Barry C. Westreich (2)
Office of Nuclear Reactor 1 Regulation U.S. Nuclear Regulatory Commission 1; White Flint, North, Mail Stop 13E16 11555 Rockville Pike Rockville, MD 20852-2738
, Manager, Electric Department
. Missouri Public Service Commission P.O. Box 360 Jefferson City, MO 65102 Ron,Kucera
-Department of Natural Resources P.O. Box 176 Jefferson City, MO 65102 Don Woodlan TU Electric P.O. Box 1002 Glen Rose, TX 76043--
Pat Nugent Pacific Gas & Electric Regulatory Services P.O. Box 156-Avila Beach, CA 93424
l ULNRC-3673
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ATTACIIAIENT ONE SIGNIFICANT IIAZARDS EVALUATION
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Page 1 of 6 SIGNIFICANT IIAZARIE CONSIDERATION INTRODUCTION This amendment application includes changes to Technical Specification Tables 2.2-1, 4.3-1, and 3.3-4, as well as their associated Bases, in order to reduce repeated alanns, rod blocks, and panial reactor trips that continue to manifest themselves, especially during beginning of cyde operation following refueling outages. Besides the potential fo' uistracting operator attention away from more safety significant evolutions, these occurrences have also led us to reduce power during surveillance testing in order to avoid reactor trips, since the channel being tested is placed in the tripped condition.
These changes to various setpoint terms associated with the Overtemperature iT, Overpower AT, and SG Water level Low-I.ow Vessel AT (Power-1 and Power-2) reactor trip and AFW start ESFAS functions will improve plant operations and reduce the potential for unnecessary reactor trips, with no detrimental effect on the plant's j
safety analysis or licensing basis.
DESCRIlrI' ION OF CIIANGFS Deletion of TA. Z. and S Setooint Terms Column entries for the Total Allowance (TA), Z, and S setpoint terms for the AT functions are deleted. The affected Functional Units in Technical Specification Table 2.2-1 are 7 - Ovenemperature AT, 8 - Overpower AT,13.a - SG Water Level Low-Low Vessel AT (Power-1), and 13.b - SG Water Level Low-Low Vessel AT (Power-2). The affected Functional Units in Technical Specification Table 3.3-4 are associated with the start of the auxiliary feedwater pumps upon SG Water Level Low-
- I.ow, i.e., Functional Units 6.d.1) a and 6.d.2).a - Vessel AT (Power-1) and Functional Units 6.d.1).b and 6.d.2).b - Vessel A'l (Power-2). As discussed in the ITS Conversion Amendment Request, optional TS ACTION b.1 in current Technical Specifications 2.2.1 and 3.3.2 is not used at Callaway (Administrative Change Number 2-02-A in Enclosure 3A/3B of Attachment 9 to Refemnce 1). As such,' them is no need
'to retain the TA, Z, and S setpoint terms in the Technical Specifications since they have. meaning at Callaway only in the context of the setpoint calculations, i.e., current practice is to apply ACTION b.2. Prior to the approval of the ITS Conversion
^
Amendment, the affected Functional Units will apply current TS ACTION b.2.
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Page 2 of 6' Setnoint Changes The Nominal Trip Setpoint (K ) for the Overtemperature AT trip function has been i
increased from 1.15 to 1.1950, an increase of 4.5% RTP or 3 % AT span. _The -
Allowable Value for the Overtemperature AT trip function has beer. increased by 2.9%
RTP or 1.93% AT span. The Nominal Trip Setpoint (K ) for the Overpower AT trip 4
function has been increased from 1.09 to 1.1073, an increase of 1.73 % RTP or 1.15 %
AT span. The Allowable Value for the Overpower AT trip function has been virtually left unchanged (decreased by 0.05 % RTP or 0.03 % AT span). The Nominal Trip Setpoints for the Vessel AT Power-1 and Power-2 poitions of the SG Water Level Low-Low RTS and ESFAS trip functions have been increased by 2.41 % RTP; their Allowable Values have not been changed, There have been no changes to the Safety Analysis Limits (K = 1.79, K = 1.165, Vessel AT Power 1 = 19% RTP, Vessel AT i
4 Power 2 = 29% RTP) listed in FSAR Table 15.0-4. As such, no previously perfonned accident analyses are impas ed.
Moving the Nominal Trip Setpoints and the Allowable Value (Overtemperature AT only) above the values requested in References 2 through 4 and approved in References 5 through 7, closer to the respective Safety Analysis Limits, is accommodated by the following:-
1, Use of available setpoint margin. The Westinghouse setpoint methodology _
requires that the difference between the Safety Analysis Limit (SAL) and the Nominal Trip Setpoint, dermed as the Total Allowance (TA), equal the Channel Statistical Allowance (CSA) which accounts for the entire channel setpoint uncertainty.1 When the TA exceeds the CSA, that margin is
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available for future licensee use. All changes propased herein still retain 0.5% AT span for margin.
- 2. _ Changes to the Process Measurement Accuracy (PMA) term. In References 2 through 4, the PMA term included both random and systematic error components associated with hot leg streaming. As discussed below, both of these PMA ermr components can be addressed by including biases to compensate for "burndown effects" on AT and T,y. Power tends to redistribute radially outward from the core center as burnup progresses 1
- during a cycle. This affects the streaming in the hot legs, as the water from -
the center of the core becomes cooler than it was at BOL. Thus, the -
indicated average Tao, tends to decrease, resulting in a decrease in the indicated AT. This nill be referred to as a AT "burridown effect".
. This removes these error components fmm the square-root-sum-of-squares
-(SRSS) treatment in the CSA, replacing them with algebraically added 4
' Attachment l'
- Page 3 of 6 biases. Periodic renormalization of the loop specific AT and T.,, values, as per Technical Specification Table 4.3-1 Note (6) and the Bases, will be performed if tiie "burndown effect" biases are exceeded (the revision to Note (6) contained herein denotes a previous editorial oversight regarding T.,,). This will ensure that hot leg stmaming will not adversely impact the AT and T.,, portions of these AT t ip functions.
In addition, the Ph1A term for the Overtemperature AT function in Reference 2 included an error component cormsponding to the 2% value in Technical Specification Table 4.3-1 Note (3). If the absolute difference between incore and excore axial flux difference (AFD) is _> 2% during the montiily surveillance, the channel must be recalibrated. This PhiA tenn is overly conservative in that setpoint margin is always used even when the AFD penalty function from Technical Specification Table 2.2-1 Note 1 is not imposed, i.e., even when the AFD is within the deadband where no trip setpoint penalty is imposed. This PhiA error component will no longer be treated as a random tenn in the CSA; rather, it will be applied as a bias only when the AFD !s outside the deadband. The elimination of the random Ph1A error component is therefore justified by moving the AFD penalty function deadband in by a corresponding 2% on both sides.
- 3. Elimination of sensor calibration accuracy and sensor drift error components for the RTDs. Periodic renonnalization of each loop's ATo, T', T" parameters wih be performed if required due to exceeding the "burndown effect" biases ducing a quarterly surveillance. This will compensate for the uncertainly in the cross-calibration of the RTDs. In addition, a power calorimetric error component has been added to the Ph!A term to account for the accuracy of the seconuary side power calorimetric. Thus, the RTD sensor calibration accuracy error component has been eliminated. In addition, the addition of the "burndown effect" biases accounts for the RTD sensor drift error component, y
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- 4. Reduction in the rack drift error component. Plant data support a reduction in the magnitude of this error from what had been previously assumed.
- 5. - Elimination of the seismic allowance bias from the Oventemperature AT setpoint calculation. This seismic allowance was originally included by Westinghouse as a wsult of minor setpoint shifts in the 7300 Process Protection System NCH (Function Generator) and NPC (Potentiometer) cards observed during seismic qualification testing. However, the Overtemperature AT trip function is not required to provide plant protection coincident with any seismic events. Westinghouse included this Sias to account for the folle ~ing sequence of events: a less than OBE level m_..
Athcluneet 1 Page 4 of o canhquake occurs for which no plant shutdown is required; the AFD penalty function NCil/NPC card potentiometers shift and aren't corrected; and, some time later, a plant transient occurs that requires OTAT protection. To suppon climination of this bias and to pmtect against this sequence of events, the plant seismic response procedure for any gmund motion sullicient to actuate the scismic annunciators (> 0.Olg) has been revised to specifically evaluate the impact on the AFD penalty function cards, including the perfonnance of panial channel ACOTs, if necessary, to ensure that seismic-induce <l errors are not introduced.
As discussed in Reference 1, Union Electric considers the Allowable Value to be the LSSS, the value which detennines channel operability. In the above changes, only the Ovenemperature AT reactor trip function has an increased Allowable Value. The l
changes to that Allowable Value are more than compensated for by the use of available I
setpoint margin and by the elimination of the seismic allowance blas, linLip Strenming Radial power redistribution over the lerigth of a cyle has a direct effect on hot leg streaming. Typically. Beginning Of Life (BOL) power levels are highest in the center of the core, which results in corresponding higher water tem [uatures in central vs.
peripheral regions of the upper plenum. These regions do not complete:y mix at the hot leg nozzles and substantial tempemture gradients persist as fluid is transponed l
down the hot leg. Specific placement of hot leg RTDs detennines what ponion of the temperature gmdient each detector is exposed to A single RTD may be measuring either the relatively colder water from the outside asseniblies or the relatively hotter water from the center of the core. Taking tM mean value of three temperature measurements in a hot leg cross-sectional plane, 'herefore, does not necessarily provide an accumte indication of the bulk fluid temperature.
Changes in the relationship between AT and total core power detennined by a secondary calorimetric am attributable to burndown effects. If ATo is detennined at BOL, a decrease in measured full power AT due to burndown effectively increases the margin to trip. That is, burndown effects cause the trip channel to use a AT less than that indicated by the secondag eatorimetric. Burndown effects on AT are therefore treated as a bias since they demonstrate a measurable, systematic (vice random)
(chavior.
Based on Callaway experience, AT burndown can be bounded with an allowance of 1.0'F. That is, ATo hculd not change due to burndown more than 1.0"F during any s
quanerly surveillance interval.
Attaclunent 1 Page 5 of 6 T,,, burndown also trends in the direction of decreasing indicated T.,,, potentially delaying the associated subchannel penalties in OTAT and OPAT. To account for this T.,, burndown effect, a bias equal to 1/2 of the AT burndown allowance is included in the setpoint calculation. Callaway experience has shown that an allowance of 0.5*F is sufncient to bound this effect.
10CIHS.92 FNALUATION The proposed changes m the Technical Specifications do not involve a significant hazards consideration because operation of Callaway Plant in accordance with these changes would not:
(1)
Involve a signincant increase in the protability or consequences of an accident previously evaluated.
Overall protection system perfonnance will remain within the bounds of the previously perfonned accident analyses since no hardware changes are proposed. The protection systems will continue to function in a manner consistent with the plant (lesign 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 perfonn its intended function. There will be no degradation in the perfonnance of nor an increase in the number of challenges imposed on safety-related equipment assumed to function during an accident situation. There will be no change to nonnal plant opemting parameters or accident mitigation capabilities. Then: fore, the proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.
(2)
Create the possibility of a new or different kind of accident from any accident previously evaluated.
There are no hardware changes associated with this license amendment nor are thcre any changes in the method by which any safety-related plant system perfonns its safety function. The nonnal manner of plant operation is unchanged. The Overtemperature AT Allowable Value increase is justified by the use of existing setpoint margin and elimination of conservatisms not required by the safety analysis and licensing basis.
There will be a reduction in the incidence of alanns, rod stops, and partial reactor trips. There will be also be less of a need to reduce power during on line surveillance testing. These changes represent substantial plant operational improvements.
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Attachment i Page 6 of 6 No new accident scenarios, transient pitcursors, failure mechanisms, or limiting single failures are intmduced as a result of these changes. There will be no adverse effect or challenges imposed on any safety related system as a result of these changes. Therefore, the pmposed changes do not create the possibility of a new or different kind of accident from any previously evaluated.
(3)
Involve a signincant n: duction in a margin of safety.
The proposed changes do not affect the acceptance criteria for any analyzed event nor is there a change to any Safety Analysis Limit (SAL).
Maintaining the SAL pn:scrves the margin of safety.
There will be no effect on the manner in which safety limits or limiting safety system settings are detennined nor will there be any effect on those plant systems necessary to assure the accomplishment of protection functions. There will be no impact on the overpower limit, DNBR limits, F, Fall, LOCA PCT, peak local power density, or any other margin of Q
safety.
CONCLUSION Based upon the preceding infonnation, it has been detennined that the pmposed changes to the Technical Speci0 cations do not involve a signincant increase in the probability or consequences of an accident previously evaluated, create the possibility of a new or different kind of accident fmm any accident previously evaluated, or involve a significant reductian in a margin of safety. Therefore, it is concluded that the proposed changes meet the requirements of 10CFR50.92(c) and do not involve a significant harards consideration.
ULNRC-3673 A1TACllMENT Two ENVIRONAiENTAL CONSIDERATION 4
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i Page1of1 ENVIRONMENTAL CONSIDFRATION l
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This amendment application includes changes to Technical Specification Tables 2.2 1, j
4.31, and 3.3 4, as well as their associated Bases, in order to reduce repeated alanns, I
i
- nxi blocks, and panial reactor trips that continue to manifest themselves, especially during beginning of cycle operation following refueling outages. Besides the potential i
for distracting operator attention away from more safety significant evolutions, these j'
occunrnees have also led us to mduce power during surveillance testing in order to avoid reactor trips, since the channel being tested is placed in the tripped condition.
These changes to various setpoint terms associated with the Ovenemperature AT, Overpower AT, and SG Water Level low Low Vessel AT (Power-1 and Power-2) l reactor trip and AFW stan ESPAS functions will improve plant operations and reduce the potential for unnecessary reactor trips, with no detrimental effect on the plant's safety analysis or licensing basis.
i l
The proposed amendment involves changes with respect to the use of facility j
j components located within the restricted area, as defined in 10CFR20. Union Electric j
has detennined that the proposed amendment does not involve:
l (1)
A significant hazards consideration, as discussed in Attachment 1 of this j
amendment application; a
).
(2)
A signincant change in the types or sign 10 cant increase in the amounts of any efnuents that may be micased offsite; 7
j (3)
A significant increase in individual or cumulative occupational radiation exposure.
' Accordingly, the proposed amendment meets the eligibility criteria for categorical exclusion set fonh in 10CFR51.22(c)(9). Pursuant to 10CFR51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.
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