ML20063G324
| ML20063G324 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 02/10/1994 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20063G327 | List: |
| References | |
| ULNRC-2954, NUDOCS 9402160022 | |
| Download: ML20063G324 (16) | |
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Donald f. SchacIl F2LECTRIC February 10, 1994 Sen r vce Pn dera uw 323 U.S. Nuclear Regulatory Commission Attn:
Document Control Desk Mail Station P1-137 Washington, D.C.
20555 ULNRC-295 4 Gentlemen:
DOCKET NUMBER 50-483 CALLAWAY PLANT REACTOR TRIP ON REACTOR COOLANT PUMP UNDERVOLTAGE
References:
1.
SLNRC 84-0050 dated March 23, 1984, Response to NRC Questions on Setpoint Methodology
- 2. ULNRC-1822 dated August 30, 1988, Steam Generator Level Reactor Trip Modification (EAM/TTD)
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 Table 2.2-1 as well as Bases Section 2.2.1.
Functional Unit 14 of Table 2.2-1, Undervoltage - Reactor Coolant Pumps, is revised to correct the Total Allowance in order to reflect the undervoltage relay span and to correct the Allowable Value to reflect the rack measurement and test equipment (M&TE) uncertainty.
The Reactor Coolant Pumps (RCPs) are powered by 13.8 kV buses-PA01 and PA02.
The Trip Setpoint and Allowable Value for Functional Unit 14 are expressed in terms of voltages on those buses.
- However, the Total Allowance, Z,
and S values are expressed in-percent of the undervoltage relay span (calibrated span of 70-100 volts).
The Safety Analysis Limit reported in FSAR Table 15.0-4 (68% of the nominal RCP bus voltage or 9384 Vac) and the trip setpoint of 10584 Vac reported in Table 2.2-1 are not changed nor are the Z and S values.
Changes to the Bases have been made to clarify the relationship between the 13.8 kV power supply and the 120 Vac undervoltage relays.
The Callaway Plant Onsite Review Committee and the Nuclear Safety Review Board have reviewed this r,
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amendment application.
Attachments 1 through.4 provide the Safety Evaluation, Significant Hazards. Evaluation,
-Environmental Consideration, and. proposed Technical Specification revisions, respectively, in support of this-request.
It has been determined that this amendment application does not involve an unreviewed safety question as determined per 10CFR50.59 nor a significant hazard consideration 1as determined 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.-
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If you have any questions on the attachments, please contact us.
Very truly yours, C
n Donald F. Schnell GGY/dls Attachments:
1 - Safety Evaluation 2 - Significant Hazards Evaluation 3 - Environmental Consideration 4 - Proposed Technical Specification Revisions e
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5 STATE OF MISSOURI
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t Donald F.
Schnell, of lawful age, being first duly sworn
'upon oath says that he is Senior Vice President-Nuclear and an: officer of Union Electric Company; that he has read the foregoing document and' knows the content thereof; that he has executed the same-for and on.
c behalf of said company with full power and authority to do so; and'
-that'the facts therein stated are true and correct to the best of'his knowledge, information and belief.
By
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Donald F. Schnell Senior Vice President Nuclear i
SUBSCRIBED and sworn to before me this
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BARBARA LUNGWITZ E~ {,
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Baxter, Esq.-
Shaw, Pittman, Potts & Trowbridge 2300 N. Street, N.W.
Washington, D.C.
20037 M. H.
Fletcher CFA, Inc.
18225-A Flower Hill Way Gaithersburg, MD 20879-5334 t
L. Robert Greger Chief, Reactor Project Branch 1 U.S.
Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 Bruce Bartlett
.I Callaway Resident Office U.S.. Regulatory Commission RR#1 Steedman, Missouri 65077 t
i L. R. Wharton (2)
Office of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Commission 1 White Flint, North, Mail Stop 13E21 11555 Rockville Pike Rockville, MD 20852 Manager, Electric Department Missouri Public Service Commission
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Box 360 Jefferson City, MO 65102 Ron Kucera Department of-Natural Resources P.O.. Box 176 Jefferson City, MO 65102 9
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Page 1 of 4 SAFETY EVALUATION INTRODUCTION This amendment application includes changes to Technical Specification Table 2.2-1 as well as Bases Section 2.2.1.
Functional Unit 14 of Table 2.2-1, Undervoltage - Reactor Coolant Pumps, is revised to correct the Total Allowance in order to reflect the undervoltage relay span and to correct the Allowable Value to reflect the rack measurement and test equipment (M&TE) uncertainty.
The Reactor Coolant Pumps (RCPs) are powered by 13.8 kV buses PA01 and PA02.
The Trip Setpoint and Allowable Value for Functional Unit 14 are expressed in terms of voltages on those buses.
However, the Total Allowance, Z,
and S values are expressed in percent of the undervoltage relay span (calibrated span of 70-100 volts).
The Safety Analysis Limit (SAL) reported in FSAR Table 15.0-4 (68% of the nominal RCP bus voltage or 9384 Vac) and the trip setpoint of 10584 Vac reported in Table 2.2-1 are not changed nor are the Z and S values.
Changes to the Bases have been made to clarify the relationship between the 13.8 kV power supply and the 120 Vac undervoltage relays.
DESIGN CONSIDERATIONS The reactor trip on RCP undervoltage serves to protect the reactor against a departure from nucleate boiling (DNB) due to low flow conditions brought on by low voltage to the RCPs (e.g.
i due to a loss of offsite power or RCP breakers opening).
Flow-from the RCPs decreases slightly as voltage to the motors is lowered and then is rapidly reduced as pullout torque is exceeded by the load torque.
The SAL is therefore set at a sufficiently
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high value that pullout torque would not be exceeded.
There is one potential transformer (PT), with a primary to secondary ratio of 14400:120, connected in parallel with the 13.8 kV power supply to each RCP motor at the motor side of the supply breaker.. Each PT secondary side is connected to an undervoltage relay (GE type NGV, 120.Vac, calibrated span 70-100 volts) and time. delay relay (Westinghouse type TD-5) as well as a separate underfreqency relay (Westinghouse type SDF-1).
The undervoltage relays provide output signals to the SSPS which trips the reactor, if permissive P-7 issatisfied (i.e. greater than 10% of rated thermal power),
.when the voltage at one out of two RCP motors on both PA system buses drops below 10584 Vac.
The time delay relay prevents spurious trips caused by transient voltage perturbations.
The undervoltage trip is the primary trip function credited in the-analysis of a Complete Loss of Forced Reactor Coolant Flow in FSAR Section 15.3.2.
The complete loss of flow analysis _is unaffected by this amendment application since the SAL and nominal trip setpoint are unchanged.
RCP UNDERVOLTAGE SETPOINT TERMS The Total Allowance represents the difference between the nominal trip setpoint and the SAL.
As discussed above, these values are 10584 Vac and 9384 Vac for a difference of 1200 volts.
- However, since the values of Total Allowance, Z, and S as reported in
Page 2 of 4
~ Technical Specification Table 2.2-1 are in terms of the measuring-element's span, these PA system bus voltages must be related to
'the corresponding voltages at the undervoltage relays.
With a ratio of 14400:120, the trip setpoint and SAL correspond to 88.2 and 78.2 volts, respectively, at the undervoltage relays.
The Total Allowance is therefore 10 volts.
In terms of percent span, this is 33.3% of a 30 volt span.
The 7.7% of span value currently listed in Table 2.2-1 and provided to NRC in Reference 1 of the cover letter is incorrect.
Further, it is noted that Reference 1 specified a rack measurement and test equipment (M&TE) allowance for all of the RPS/ESEAS trip functions covered with the exception of the RCP
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Undervoltage trip.
The setpoint calculations have been revised to reflect both the change in Total Allowance above and to include a rack M&TE allowance.
The M&TE allowance used corresponds to a standard hand held Keithley 197 multimeter.
Although the M&TE allowance is large when converted to a percent of the undervoltage relay span, the setpoint margin is more than large enough to accommodate it.
While specific values.of the individual setpoint uncertainty terms are held as proprietary by Westinghouse (as witnessed by the two versions of the attachment to Reference 1 of the cover letter), the equations for Allowable Value have been provided in the non-proprietary WCAP-11884 submitted via Reference 2 of the cover letter.
As seen in Note 3 to Table 4-6 of WCAP-11884, the value for T1 (T3 does not apply since this trip function does not have multiple variable inputs as does OT Delta-T) depends on, and is increased by, the rack M&TE allowance.
Since the Allowable Value is determined by the difference between the nominal trip setpoint and the minimum of T1 or T2 (T1 is emaller in this case per the revised setpoint calculation), raising Ti has the effect of lowering the Allowable Value from 10356 Vac to 10105 Vac.
As stated before, use of a relatively large value for the rack M&TE allowance is more than compensated for by the even larger available setpoint margin.
The dual approach in listing the_setpoint values in Table 2 2 in both percent of the undervoltage relay span and in voltages seen by the RCP motor, in conjunction with the design scope interface, i.e. the 13.8 kV power supply and potential transformer feeding the undervoltage_ relays were designed by the-A/E and supply trip signals to the NSSS reactor protection system which had setpoint analyses performed by the NSSS vendor, led to the above discrepancies.
The only other similarly designed and analyzed trip function in Table 2.2-1, Functional Unit 15 RCP Underfrequency, has been verified to be correct.
DETERMINATION OF NO UNREVIEWED SAFETY OUESTION The proposed changes.to the Technical Specifications do not involve an unreviewed safety question because the_ operation of Callaway Plant in accordance with these proposed changes would not:
- 1) Involve an increase in the probability of occurrence or the consequences of an accident or malfunction of equipment important_to safety previously evaluated in the FSAR.
Overall
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Pago 3 of 4 protection system performance will remain within the bounds of the accident analyses _ documented in FSAR Chapter 15, WCAP-10961-P, and WCAP-11883 since no hardware changes are proposed.
The RCP undervoltage reactor trip function is a primary trip function and is credited in FSAR Section 15.3.2, Complete Loss of Forced Reactor Coolant Flcw.
The trip setpoint is designed-to ensure plant operation within the DNB design basis.
There will be no effect on this analysis, or any other accident analysis, since the safety analysis limit and trip response time are unaffected and remain the same as discussed in FSAR Section 15.0.6 and FSAR Table 15.0-4.
The RCP undervoltage reactor trip will continue to function in a manner consistent with the above analysis assumptions and the plant design basis.
As such, there will be no degradation in the performance of nor an increase in the number of challenges to equipment assumed to function during an accident situation.
These Technical Specification revisions do not involve any hardware changes nor do they affect the probability of any event initiators.
There will be no change to normal plant operating parameters, ESF actuation setpoints, accident mitigation capabilities, accident analysis assumptions or inputs.
Therefore, these changes will not increase the probability or consequences of an accident or malfunction.
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- 2) Create the possibility for an accident or malfunction of a different type than any previously evaluated in the FSAR.
As discussed above, there are no hardware changes associated with these Technical Specification revisions nor are there any changes in the method by which any safety-related plant system perforns its safety function.
Changes to the Total Allowance and Allowable Value terms in Technical Specification Table 2.2-1 will require only minor changes to the acceptance criteria sections of a few surveille.nce procedures.
The normal manner of plant operation is unaffected.
If an undervoltage relay setpoint is found to be below the nominal trip setpoint in Table 2.2-1, entry into Action Statements a or b of Specification 2.2.1 will'be affected insofar as the Allowable Value is being lowered and the Total Allowance value contained in Equation 2.2-1 is being raised.
However, the nominal trip setpoint is unchanged and the required plant condition for ex:~ ting the Action Statements, i.e. adjusting the trip setpoint consistent with the Table 2.2-1 value, is likewise unchanged.
The revisions to the Total Allowance and Allowable Value correct errors in their derivation and were calculated using the previously approved Westinghouse setpoint methodology.
The setpoint equations cited in that methodology are unchanged; however, i
inputs to those equations have been revised to reflect the undervoltage relay span and the rack M&TE uncertainty.
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Attachm:nt 1 Page 4 of 4 No new accident scenarios, transient precursors, failure mechanisms, or limiting single failures are introduced as a 3
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 possibility of a new or different type of accident is not created.
There.are no changes which would cause the malfunction of safety-related equipment, assumed to be operable in the accident analyses, as a result of the proposed Technical Specification changes.
No new mode.of failure has been created and no new equipment performance burdens are. imposed.
Therefore, the possibility of a new or different malfunction of safety-related equipment is not created.
- 3) Involve a reduction in the margin of safety as defined in'the basis for any Technical Specification.-'There will be no change to the DNBR Correlation Limit, the design DNBR limits, or the safety analysis DNBR limits discussed-in Bases Section' 2.1.1.
As discussed previously, the response time of the RCP undervoltage reactor trip function will remain within the assumptions used in the accident analyses.
The analysis of l
the complete loss of flow accident will remain as presented in-
'FSAR Section 15.3.2.
There will be no effect on the manner in which. safety limits i
or limiting safety system settings are determined nor will there be any effect on those plant systems necessary to assure the accomplishment of protection functions.
There will be.no o
impact on DNBR limits, Fg, F-delta-H, LOCA PCT, peak local power density, or any other margin of safety.
The safety analysis limit, 9384 Vac at the RCP motor, and the nominal i
trip setpoint, 10,584 Vac, remain the same as before.-
t Based on the information presented above, the proposed amendment i
does not involve an unreviewed safety question and will not adversely affect or endanger the health or safety.of the general public.
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.'i SIGNIFICANT HAZARDS EVALUATION.
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Page 1 of 3 SIGNIFICANT HAi3RDS EVALUATION This_ amendment application includes changes to Technical Specification Table 2.2-1 as well as Bases Section 2.2.1.
Functional Unit 14 of Table 2.2-1, Undervoltage - Reactor Coolant Pumps, is revised to correct the Total Allowance in order to reflect the undervoltage relay span and to correct the Allowable Value to reflect the rack measurement and test equipment (M&TE) uncertainty.
The Reactor Coolant Pumps (RCPs) are powered by 113.8 kV buses PA01 and PA02.
The Trip Setpoint and Allowable Value for Functional Unit 14 are expressed in terms of voltages on those buses.
However, the Total Allowance, Z,
and S values are expressed in percent of the undervoltage relay span (calibrated span of 70-100 volts).
The Safety Analysis Limit (SAL) reported in FSAR Table 15.0-4 (68% of the nominal RCP bus voltage or 9384 Vac) and the trip setpoint of'10584 Vac reported in Table 2.2-1 are not changed nor are the Z and S values.
Changes to the Bases have been made to clarify the relationship between the 13.8 kV power supply and the 120 Vac undervoltage relays.
The proposed changes to 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 significant increase in the probability or consequences of an accident previously evaluated.
Overall protection system performance will remain within the bounds of the accident analyses documented in FSAR Chapter 15, WCAP-10961-P, and WCAP-11883 since no hardware changes are proposed.
The RCP undervoltage reactor trip function is a primary. trip function and is credited in FSAR Section 15.3.2, Complete Loss of Forced Reactor Coolant Flow.
The trip setpoint is designed to ensure plant operation within the DNB design basis.
There will be no effect on this analysis, or any other accident analysis, since the safety analysis limit and trip response time are unaffected and remain the same as discussed in FSAR Section 15.0.6 and FSAR Table 15.0-4.
The RCP undervoltage reactor trip will continue to function in a manner consistent with the above analysis assumptions and the plant design basis.
As such, there will'be no degradation in the performance of nor an increase in the number of challenges to equipment assumed to function during an accident situation.
These Technical Specification revisions do not involve any hardware changes nor do they affect the probability of any j
event initiators.
There will be no change to normal plant j
operating parameters, ESF actuation setpoints, accident i
mitigation capabilities, accident analysis assumptions or i
inputs.
Therefore, these cha"ges will not increase the i
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probability _or consequences of an accident previously evaluated.
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- 2) Create the possibility of a new or different kind of accident from any previously evaluated.
As discussed above, there are no hardware changes associated with these Tecnnical Specification revisions nor are there any changes in the method by which any safety-related plant system performs its safety function.
j Changes to the Total Allowance and Allowable Value terns in Technical Specification Table 2.2-1 will require only minor changes to the acceptance criteria sections of a few surveillance procedures.
The normal manner of plant operation is unaffected.
If an undervoltage relay setpoint is found to be below the nominal trip setpoint in Table 2.2-1, entry into f
Action Statements a or b of Specification 2.2.1 will be affected insofar as the Allowable Value is being lowered and i
the Total Allowance value contained in Equation 2.2-1 is being raised.
However, the nominal trip setpoint is unchanged and the required plant condition for exiting the Action Statements, i.e. adjusting the trip setpoint consistent with the Table 2.2-1 value, is likewise unchanged.
The revisions to the Total-Allowance and Allowable Value correct errors in their derivation and were calculated using the previously approved Westinghouse setpoint methodology.
The setpoint equations cited in that methodology are unchanged; however, inputs to those equations have been revised to reflect the undervoltage relay span and the rack M&TE uncertainty, No new accident scenarios, transient precursors, failure mechanisms, or limiting single failures are introduced 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 possibility of a new or different type of accident is not created.
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- 3) Involve a significant reduction in a margin of safety.
There will be no change to the DNBR Correlation Limit, the i
design DNBR 'imits, or the safety analysis DNBR_ limits discussed in Bases Section 2.1.1.
i As discussed previously, the response time of the RCP undervoltage reactor trip function will remain within the assumptions used in the accident analyses.
The analysis cf the complete loss of flow accident will remain as presented la-FSAR Section 15.3.2.
There will be no effect on the manner in which sa2ety limits' l
or limiting safety system settings are determined nor will there be any effect on those plant systems necessary to assure the accomplishment of protection functions.
There will be_no
-i impact on DNBR limits, F, F-delta-H, LOCA PCf, peak local O
power density, or any other margin of safety.
The safety f
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Page13 of 3 analysis limit, 9384 Vac at the RCP motor, and the nominal trip setpoint, 10,584 Vac, remain the same as before.
Based upon the preceding information, it has been determined that the proposed changes to the Technical Specifications do not involve a significant increase in the probability or consequences of an accident previously evaluated, create the. possibility of a new or different kind of accident from any accident previously evaluated, or involve a significant reduction 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 hazards consideration.
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ATTACHMENT THREE i
ENVIRONMENTAL CONSIDERATION f
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Page 1 of 1 EINIRONMENTAL CONSIDERATION This amendment application includes changes to Technical Specification Table 2.2-1 as well as Bases Section 2.2.1.
Functional Unit 14 of Table 2.2-1, Undervoltage - Reactor Coolant Pumps, is revised to correct the Total Allowance in order to reflect the undervoltage relay span and to correct the Allowable Value to reflect the-rack measurement and test equipment (M&TE)'
uncertainty.
The proposed amendment involves changes with respect to the use~
of facility components located within the restricted area, as defined in 10CFR20, and changes surveillance requirements.
Union Electric has determined that the proposed amendment does not involve:
- 1) A significant hazards consideration, as discussed in of this amendment application;
- 2) A significant change in the types or significant increase in the amounts of any effluents that may be released offsite;
- 3) A significant increase in individual or cumulative occupational radiation exposure.
Accordingly, the proposed amendment meets the eligibility criteria for categorical exclusion set forth in -10CFR51.22 (c) (9).
PurPlant to 10CFR51.22 (b), no environmental impact statement or environmental assessment need be prepared in connection with the t
issuance of this amendment.
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ATTACHMENT FOUR i
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PROPOSED TECHNICAL SPECIFICATION REVISIONS
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