ML20248J709
| ML20248J709 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 04/06/1989 |
| From: | Hairston W GEORGIA POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20248J712 | List: |
| References | |
| ELV-00390, ELV-390, NUDOCS 8904170015 | |
| Download: ML20248J709 (10) | |
Text
- -- -
. +_ %
o' '
- ^
[Georga her Ccrneahy ,
I h,, e t
. 'i33 Pecdo] cry k;ons 57{r
- A,%4(Wc'gq FOS ~k fi& phone amt 526 JW5 Mdng A$bss:
40 br;OfIntS3 CodM Pabhy
~
FEt OfIce Doi 12%
B.rmir:gham Aiarcama 3PC)
Itighorm 205 P63-9581 e ;;u nm arir wt ,
W. O. Hairston m Senior V ce Freutent nx em opmaoors ELV-00390 0220e April 6, 1989 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. ~20555
' PLANT V0GTLE - UNITS 1 AND 2 NRC DOCKETS 50-424, 50-425
' OPERATING LICENSES NPF-68, NPF-81 REVISION TO TECHNICAL SPECIFICATION 4.5.2.h.1)b)
Gentlemen:
In accordance with the provisions of 10.CFR 50.90 and 10 CFR 50.59, Georgia Power Company (GPC) hereby proposes to amend the Vogtle Electric Generating Plant _ (VEGP) Units 1 and 2- Combined Technical Specifications, Appendix A to Operating Licenses NPF-68 and NPF-81.
_ By :its ictter of March 8,1989 the NRC issued ' amendments to the VEGP Unit 1.11 cense. 3nd the VEGP Unit 2 license that consisted of changes to the VEGP Combined' Units l ' and 2 Technical Specifications in response to the Emergency Techn_ical Specification change request contained in G_PC letter ELV-00325 dated March 6, 1989. The amendments modified. Technical Specification 4.5.2.h.1)b) to increase. the . Unit 2 ; maximum - total charging ;
pump flow rate with a single pump running, from 550 gpm to 555 gpm. The l change was requested on an emergency basis in order to avoid delay in the '
start-up 'of VEGP Unit 2. Since _ the schedular considerations were only .
applicable to VEGP Unit 2, the change could not be requested for Unit 1 on i an emergency basis. The purpose of this Technical Specification change is to revise the maximum total charging pump fl ow rate with a single pump !
running from 550 gpm to 555 gpm for VEGP Unit 1. This will result in the same Technical Specification requirement for both Units.
Enclosure 1 provides a detailed description of the proposed change, and the circumstances necessitating the change request.
Enclosure' 2 provides the basis for a determination that the proposed change does not involve significant hazards considerations. I
[
8904170015 89040644 ((Il DR ADOCK O
/ [
Georgia Power d )
U. S. Nuclear Regulatory Commission
! ELV-00390 Page 2 Enclosure 3 provides instructions for incorporating the proposed change into the Technical Specifications. The proposed revised page for the i combined VEGP Units 1 and 2 Technical Specifications is included wi th Enclosure 3.
Pursuant to the requirements of 10 CFR 50.91 , the designate /. state official will be sent a copy of this letter and all applicable enclosures.
Mr. W. G. Hairston, III states that he is a Senior Vice President of Georgia Power Company, and is authorized to execute this oath on behalf of j Georgia Power Company and that to the best of his knowledge and belief, the l facts set forth in this letter and enclosures are true.
GEORGIA POWER COMPANY i
I By: h, (( f W. G. Hairston, III Sworn to and Subscribed before me this b*1 day of 6L 1989.
UkLvr YWhY Notary Pyplic El COMMISSION EXPlRES DEC.15,!972 WGH/HWM/gm
Enclosures:
xc w/ enclosures:
Georgia Power Company Mr. P. D. Rice Mr. C. K. McCoy Mr. G. Bockhold, Jr.
Mr. J. P. Kane Mr. J. A. Bailey U.S. Nuclear Regulatory Commission Mr. S. Ebneter, Regional Administrator Mr. J. B. Hopkins, Licensing Project Manager, NRR (2 copies)
Mr. J. F. Rogge, Senior Resident Inspector - Operations, Vogtle State of Georgia Mr. J. L. Ledbetter, Cormiissioner, Department of Natural Resources
i ENCLOSURE 1 PLANT V0GTLE - UNITS 1 AND 2 NRC DOCKETS 50-424, 50-425 OPERATING LICENSES NPF-68, NPF-81 REVISION TO TECHNICAL SPECIFICATION 4.5.2.h.1)b) '
BASIS FOR THE CHANGE This proposed change will raise the maximum flow rate for the VEGP Unit 1 Technical Specification Surveillance Requirement 4.5.2.h.1)b) from 550 gpm to 555 gpm.
During the pre-operational test program on VEGP Unit 2, ECCS throttle valves 1204 U4-022, 023, 024, 025 were set such that the maximum flow rate was slightly in excess of the value stated in the surveillance requirement. j This error was discovered on March 2,1989, prior to initial entry into Mode
- 4. The pre-operational test data indicated that one of the pumps had a maximum fl ow rate of 553 gpm. Since re-adjustment of the ECCS throttle valves would have resulted in significant delay in the startup of VEGP Unit 2, a Technical Specification Change was requested on 'an emergency basis.
The effects of a 5 gpm increase in the pump flow rate were evaluated and determined to be acceptable. The evaluation was applicable to both VEGP Units 1 6nd 2, however, the Technical Specification change was only requested for Unic 2 because it was requested on an emergency basis in order to avoid delay in the startup of VEGP Unit 2. The emergency Technical Specification change was issued by the NRC on March 8,1989. That change resulted in different values for the two units.
A commitment was made to follow the emergency Technical Specification change request with an additional revi sion, on a non-emergency basis, that would apply to both units. This Technical Specification change is in response to that commitmerit and will result in the same value appearing in the Technical Specification for both units thus eliminating the possibility of confusion due to different values for the the two units.
i x
El-1 3
i ENCLOSURE 2 PLANT V0GTLE - UNITS 1 AND 2 NRC 00CKETS 50-424, 50-425 OPERATING LICENSES NPF-68, NPF-81 REVISION TO TECHNICAL SPECIFICATION 4.5.2.h.1)b) 10 CFR 50.92 EVALUATION 1
In accordance with 10 CFR 50.92, the attached proposed amendment to the VEGP Units 1 and 2 Technical Specifications has been evaluated and it has been determined that operating the facility in accordance with the proposed amendment would not involve significant hazards considerations. The basis for this determination follows:
BACKGROUND During the pre-operational test program on VEGP Unit 2, the flow rate for one Centrifugal Charging Pump (CCP) was set at 553 gallons per minute (gpm). Technical Specification (TS) 4.5.2.h.1)b) defined a maximum limit. of 550 gpm for CCP flow. As a result, the VEGP Unit 2 Technical Specification requirement was revised from 550 gpm to 555 gpm for Unit 2. This evaluation addresses the effect on the safety analyses and safety related component performance in response to the Technical Specification change from 550 gpm to 555 gpm, and is equally applicable to both Units 1 and 2. The identical Technical Specification change is being applied to Unit 1 in order that the Technical Specification for both units will be consistent.
ANALYSIS 4
]
An evaluation of the effect of a 5 gpm increase in CCP flow is provided 4 bel ow:
ECCS Performance Evaluation The Vogtle ECCS is designed to cool the reactor core and to provi de additional shutdown capability following initiation of the following accident conditions:
- Loss of Coolant Accident (LOCA), including a pipe break or a spurious relief or safety valve opening in the Reactor Coolant System (RCS) which would result in a discharge larger than that which could be made up by the normal makeup system.
- Loss of Secondary Coolant Accident, including a pipe break or spurious relief or safety valve opening in the steam system which would result in an uncontrolled steam release, or a pipe break in the secondary feedwater system.
- A Steam Generator Tube Rupture Accident.
The ECCS consists of the Centrifugal Charging pumps, Safety Injection (SI) pumps, Residual Heat Removal (RHR) pumps, accumulators, residual heat exchangers, Refueling Water Storage Tank (RWST), and the associated piping, valves, instrumentation, and other related equipment.
E2-1
_ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ -~ _ _
J ENCLOSURE 2 (Continued)
In the event of an accident, the Centrifugal Charging pumps are automatically started .on receipt of an SI- signal and aligned to take suction from the RWST during the injection phase. These high-head pumps deliver flow to the RCS at the prevailing RCS pressure.
This evaluation addresses the safety impact of a 5 gpm increase in the total ECCS charging pump flowrate, from 550 to 555 gpm. Westinghouse has reviewed this proposed modification and evaluated its effect on the Centrifugal Charging pump operability and the maximum safety injection flowrate.
Vogtle test data indicates that the minimum injection flow requirement 'l specified in the Technical Specifications (284 gpm) is satisfied with the charging pump runout flow of less than or equal to 550 gpm. Thus, the ,
safety injection flowrates previously generated for use in the accident l analyses, remain valid for a slightly higher allowable flow rate of 555 gpm. .
l The impact of an increased charging pump runout on maximum safeguards flow i also needs to be addressed. Maximum Safety Injection (SI) flow is utilized in the large break LOCA, tube rup ture and inadvertent safety injection analyses. To maximize the flow delivered to the RCS, the SI flowrates used in these accident analyses were calculated assuming an extremely high pump head in conjunction with a very low resistance. For example, the system j resistance was based on a pump head of 1200 feet at a flowrate of .550 gpm. :
However, the actual pump curve used for the analyses had a developed head of ;
2580 feet. A range between 1500 and 1750 feet at runout is indicated by the manufacturer's curve. Thus, the maximum safeguards flow provided for the safety analyses is highly conservative. The Vogtle charging pumps will ,
deliver less flow than the maximum safeguards flows that are assumed in the '
accident analyses.
Based on the above discussion, the maximum safeguards flows provided for the safety analyses continue to be highly conservative for a total ECCS charging pump flowrate of 555 gpm.
Thus, due to available equipment and analyses margins, the increase in the total ECCS charging pump flowrate from 550 gpm to 555 gpm, is acceptable. l This change will not create any new scenario that would exceed the bounds of the analyses of record.
l CCP Component Performance Evaluation l 4
The Combined Vogtle Units 1 & 2 Technical Specifications require that each j centrifugal charging pump, operating alone, satisfy the following criteria, j with the reactor. coolant system (RCS) fully depressurized: l
- 1. The sum of the three lowest branch injection line flow rates must be greater than or equal to 284 gpm. l l
- 2. The total pump flow rate must be less than or equal to 550 gpm, i (Unit 1), 555 gpm (Unit 2).
E2-2
4 ENCLOSURE 2 (Continued)
Pre-operational test data for Vogtle Unit 2 indicated that. the minimum injection flow requirement of 284 gpm was satisfied, but that the total. pump
, flow of 553 gpm exceeded the 550 gpm limitation'. Therefore, the Technical Specification value was changed for Unit 2. The minimum injection flow requirement for Unit 1 is also 284 gpm. This evaluation demonstrates the acceptability of meeting this minimum injection flow requirement with a total pump flow of 555 gpm, and is applicable to both units. The actual flowrate for the Unit 1 pumps has not changed The fact that the minimum injection requirement of 284 gpm is satisfied with the _ pump at a higher runout condition demonstrates that the safety injection '
flowrates generated for use in the accident analysis remain valid. The concern to be addressed is to demonstrate that the pump runout condition is not detrimental to proper pump operation.
The Vogtle Units 1 & 2 Centrifugal Charging pumps are Pacific Pump serial numbers 52233, 52234, 52235, and 52236. The vendor performance test curves for these . pumps are Pacific Pump test curve numbers 38033A, 38033B, 38034A !
and 38034B respectively. The Pacific Pump outline drawing No. 300-850033 recommends a maximum pump runout flowrate of 550 gpm. It has been identifled that the Vogtle pumps may operate at up to 555 gpm. The two considerations that must be evaluated for this increased runout limitation are the horsepower capability of the motor and the margin between the ,
available and required net positive suction head (NPSH). The considerations 1 are addressed as follows:
The pump performance curves indicate that the operation of the Vogtle charging pumps at 555 gpm will - require a maximum brake horsepower of i 680 HP. The charging pump motors are rated at 600 HP with a service factor of 1.15, thus the maximum horsepower for which the motor is designed is 690 llP. Therefore, the motor is capable of providing' the horsepower required for pump operation at 555 gpm. The mctor qualified ,
life is based on continuous operation at 690 HP, therefo"e, this !
operation does not reduce the motor qualified life. 1 The charging pump performance curves provide NPSH requirements to a maximum flow rate of 555 gpm for pump #52233 and to approximately 550 gpm for the other three pumps. These performance curves show that the NPSH required at 550 gpm is approximately 22 feet for the most limiting pump. Pacific Pumps has performed additional testing of this model pump which has demonstrated that the NPSH requirements remain stable through flow rates as high as 555 gpm.
1 By extrapolation of the performance curves, the requir. " NPSH at 555 gpm will not exceed 22 feet. The available NPSH at 55t,1pm has been calculated to be in excess of 83 feet. Therefore, there h substantial NPSH margin and pump operation at 555 gpm is acceptable. '
Based on the evaluation of the charging pump motor horsepower capabilities and the substantial NPSH margin which is available, it is concluded that the centrifugal charging pumps are capable of operating at 555 gpm with no damage to the pumps or degradation of pump performance. No special )
operating precautions or maintenance requirements are necessary to support operation of the pumps at 555 gpm.
E2-3
- _ _ _ _ _ _ - _ _ _ - _ - _ _ _ _ _ - - _ __ _ 1
l ENCLOSURE 2 (Continued)
Based on this evaluation, operation of the VEGP centrifugal charging pumps at 555 gpm does not adversely affect pump performance.
Steam Generator Tube Rupture Evaluation The small increase to CCP flow is more than compensated for in the amount of conservatism used in the Fluid Systems calculations to detenaine charging pump flow used in the tube rupture analysis. Based on this conservative CCP flow calculation, it is determined that the 5 gpm increase in CCP flow will not change the results of the tube rupture analysis. The CCP flows used in the tube rupture analysis remain conservative and therefore this TS change does not adversely affect the steam generator tube rupture analysis results.
LOCA and LOCA-Related Evaluation The following LOCA-related accidents do not consider the maximum runout flew of the charging pump. Since the minimum injection requirement is stili satisfied, there is no adverse affect on these accidents:
small break LOCA LOCA hydraulic forcing functions rod ejection mass releases post-LOCA long term cooling hot leg recirculation switchover to prevent boron precipitation Since the maximum ECCS safeguards large break LOCA analysis for the Vogtle units is limiting, an evaluation has been performed for the large break LOCA analysis for an increase of the charging pump runout flow by 5 gpm. For two charging pumps delivering during the maximum safeguards ECCS LOCA analysis, a total increase of 10 gpm would be seen. The evaluation demonstrated approximately a 2 0F increase in the peak cladding temperature (PCT) for the large break LOCA analysis. The current PCT for the Vogtle units is 1995.8 0F. Based on this evaluation, there is sufficient margin to the 10 CFR 50.46 PCT limit of 2200 0F to offset the PCT increase due to the increased runout flow of the charging pumps at VEGP. Therefore, there is no adverse af fect on the LOCA and LOCA-related accidents as a result of this Technical Specification change.
Non-LOCA Evaluation Maximum safety injection flow is conservatively assumed for only one non-LOCA transient, Inadvertent Operation of the Emergency Core Cooling System During Power Operation (FSAR Section 15.5.1). For all other non-LOCA transients which model safety i nj ection, a minimum flowrate is conservative. The current VEGP analysis for Inadvertent ECCS operation assumes that two charging pumps are injecting RWST water in the RCS. The pump data used in the analysis is very conservative and bounds the increase to 555 gpm. It is therefore concluded that this Technical Specification change does not adversely affect the non-LOCA safety analysis.
E2-4
ENCLOSURE 2'(Continued)
Containment Mass and Energy Analysis i The small increase in CCP flow results in an insignificant increase in the LOCA mass and energy releases when compared with the total mass of fluid released to containment following a LOCA. The res'ilting effect on the containment response is correspondingly insignificant. It is therefore concluded that this Technical Specification change .does not adversely affect the containment analysis results presented in the FSAR.
CONCLUSION It has been determined that both system and component performance will not be adversely affected by the increase in flow. Therefore, the probability of previously analyzed accidents has not been increased. Additionally, .
since no new f ailure mode or new ' limiting single fail ure has been 1 identified, the possibility of a different accident being created does not exist and the probability of a malfunction of safety related equipment has ;'
not been increased.
The increased CCP flow has been determined to have no impact or an insignificant effect on the safety analysis resul ts . Therefore, the consequences of an accident previously evaluated in the FSAR has not been ;
increased and the consequences of a malfunction of equipment has not become '
more severe. Therefore, the increase in the CCP flow from 550 gpm to 555 gpm does not result in any increase in radioactive releases as a result of normal operation or as a result of evaluated accidents.
As indicated in the above evaluations, the acceptance criteria for each of the safety analyses has not been exceeded. Therefore, tliere is no reduction in the margin of safety between the safety analysis assumptions and the Technical Specification values as defined in the basi s to the Technical i Specification.
The increase in flow will not affect the postulated causes of previously l evaluated accidents. The minimum required flow has not changed, therefore the accidents evaluated with minimum flow assumptions are not affected by this change. The increase in maximum fl ow has been demonstrated, as discussed above, to be well below the maximum values assumed in the accident-analyses. The potential increase in flow has been shown to have negligible affect on pmp and motor reli ability. Therefore, this revision to the 1 maximum allowable pump flow with a single pump running from 550 gpm to 555 gpm for Unit I will not involve a significant increase in the probability of consequences of accidents previously evaluated.
This change in allowable maximum flow rate does not involve any physical change in the plant. Should future flow adjustments allow the pump to flow at 555 gpm, it will continue to operate within its designed capability and within the safety analyses assumptions. Therefore, this revision to the !
Technical Specification does not create the possibility of a new or different kind of accident from any accident previously evaluated.
E2-5
ENCLOSURE 2 (Continued)
As discussed above, the minimum flow requirements of Technical Specifications have not changed. Evaluations have been performed which conclude that the maximum flow assumption used in those analyses continues to envelope the allowable value in the revised Technical Specification.
Therefore, the margin between the results of the analyses and the safety limit have not changed, and this revision to the Technical Specification does not involve a significant reduction in a margin of safety.
Base on the preceding analysis, GPC has determined that the proposed change to the Technical Specifications does 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. Georgia Power Company therefore concludes that the proposed change meets the requirements of 10 CFR 50.92(c) and does not involve significant hazards considerations.
i 1
E2-6
ENCLOSURE 3 PLANT V0GTLE - UNITS 1 AND 2 NRC DOCKETS 50-424, 50-425 OPERATING LICENSES NPF-68, NPF-81 REVISION TO TECHNICAL SPECIFICATION 4.5.2.h.1)b)
INSTRUCTIONS FOR INCORPORATION ,
The proposed amendment to the Technical Specifications (Appendix A to Operating License NPF-68 and NPF-79) would be incorporated as follows:
Remove page Insert page 3/4 5-6 3/4 5-6 I
E3-1 1