ML17264A924
| ML17264A924 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 06/03/1997 |
| From: | ROCHESTER GAS & ELECTRIC CORP. |
| To: | |
| Shared Package | |
| ML17264A925 | List: |
| References | |
| NUDOCS 9706240151 | |
| Download: ML17264A924 (19) | |
Text
,r eporting Requirements 5.6 5.6 Reporting Requirements
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5.6.6 PTLR (continued)
- c. The Friifjtfcalsjmeth~o, sgiised,-.,"to~dept'erpmftiieith+e:: Rcs Pressure and Tsreiiip'erature and LTOP fimits sha'fl"'be those previously reviewed and approved by the NRC.
in NRC letter dated Hay jt APP ASL!ii'jjie, PP 111 111, tt 4 4 1 4 arej~S described in the following documents:
- 1. Letter from R.C. Necredy, Rochester Gas and Electric Att Facility t':
Corporation (RG&E), to Document Control Desk,
~'4'PPALA!!!riled'i,',,'j, Operating License, Revi'sion" to Reactor Coolant "A 41
NRC, System (RCS) Pressure and Temperature Limits Report (PTLRgi'AHmfii I StrajtTvTee, OCi~itiO; 'e";:.:Rijiiifremente.,"
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- d. The PTLR shall be provided to the NRC upon issuance for each reactor vessel fluent period and for revisions or supplement thereto.
PDR ADQCK 0 P
R.E. Ginna Nuclear Power Plant 5.0-22 Amendment No. g, PP
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eporting Requirements 5.6~
5.6 Reporting Requirements 5.6.6 PTLR (continued)
C. The analytical methods used to determine the RCS pressure and temperature and LTOP limits shall be those previously reviewed and approved by the NRC in NRC letter dated [ ].
Specifically, the methodology is described in the following documents:
- 1. Letter from R.C. Hecredy, Rochester Gas and Electric Corporation (RGEE), to Document Control Desk, NRC, Attention: Guy S. Vissing, "Application for Facility Operating License, Revision to Reactor Coolant System (RCS) Pressure and Temperature Limits Report (PTLR)
Administrative Controls Requirements," Attachment VI, April 24, 1997, as supplemented by letter from R.C.
Hecredy to Guy Vissing, "Clarifications to Proposed Low Temperature Overpressure Protection System Technical Specification," Enclosure 1, June 3, 1997.
- 2. WCAP-14040-NP-A "Hethodology Used to Develop Cold Overpressure Hitigating System Setpoints and RCS Heatup and Cooldown Limit Curves," Sections 1 and 2, January, 1996, as supplemented by letter from R.C. Hecredy to Guy Vissing, "Clarifications to Proposed Low Temperature Overpressure Protection System Technical Specification," Enclosure 2, June 3, 1997.
- d. The PTLR shall be provided to the NRC upon issuance for each reactor vessel fluence period and for revisions or supplement thereto.
R.E. Ginna Nuclear'ower Plant 5. 0-22," Amendment No. Q, PP
2.0 OPERATING LIMITS The cycle-specific parameter limits for the specifications listed in Section 1.0 are presented in the following subsections. All changes to these limits must be developed using the NRC approved methodologies specified in Technical Specification 5.6.6. These limits have been determined such that all applicable limits of the safety analysis are met. All items that appear in capitalized type are defined in Technical Specification 1. 1, "Definitions."
(Reference 1)
- 2. 1. 1 The RCS temperature rate-of-change limits are:
- a. A maximum heatup of 60'F per hour.
- b. A maximum cooldown of 100'F per hour.
2.1.2 The RCS P/T limits for heatup and cooldown are specified by Figures 1 and 2, respectively.
- 2. 1.3 The minimum boltup temperature, using the methodology of Reference 4, Enclosure 2 is 60'F.
2.2 Low Tem erature Over ressure Protection S stem Enable Tem erature (LCOs 3.4.6, 3.4.7, 3.4.10 and 3.4.12)
(Methodology of Reference 3, Attachment VI and Reference 4, Enclosure 2 as calculated in Reference 3, Attachment VII).
2.2. 1 The enable temperature for the Low Temperature Overpressure Protection System is 322'F.
2.3 Low Tem erature Over ressure Protection S stem Set pints (LCO 3.4. 12) 2.3. 1 Pressurizer Power 0 crated Relief Valve Lift Settin Limits (Methodology of Reference 3, Attachment VI and Reference 4, Enclosure 2 as calculated in Reference 4, Enclosure 4).
The liftissetting for the pressurizer Power Operated Relief Valves (PORVs) s 411 psig (includes instrument uncertainty).
PTLR Revision 2
Table 3 shows calculations of the surveillance material chemistry factors using surveillance capsule data.
Table 4 provides the reactor vessel toughness data.
Table 5 provides a summary of the fluence values used in the generation of the heatup and 'cooldown limit curves.
Table 6 shows example calculations of the ART values at 24 EFPY for the limiting reactor vessel material.
5.0 REFERENCES
WCAP-14684, "R.E. Ginna Heatup and Cooldown Limit Curves for Normal Operation," dated June 1996.
- 2. WCAP-14040-NP-A, "Methodology Used to Develop Cold Overpressure Mitigating System Setpoints and RCS Heatup and Cooldown Limit Curves,"
Revision 2, January 1996.
l 3. Letter from R.C. Mecredy, RG&E, to Guy S. Vissing, NRC,
Subject:
"Application for Amendment to Facility Operating License, Revision to Reactor Coolant System (RCS) Pressure and Temperature Limits Report (PTLR) Administrative Controls Requirements," dated April 24, 1997.
- 4. Letter from R.C. Mecredy, RG&E, to Guy S. Vissing, NRC, "Clarifications to Proposed Low Temperature Overpressure Protection System Technical Specification," dated June 3, 1997.
- 5. WCAP-7254, "Rochester Gas and Electric, Robert E. Ginna Unit No. 1 Reactor Vessel Radiation Surveillance Program," May 1969.
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PTLR Revision 2
I/4 i I
base metal in the beltllne region at a distance one-fourth of the vessel section thickness from the vessel inside surface, as determined by Regulatory Guide 1.99, Revision 2. Altheugh Ybeebttl. tu'ueevCOldeCeeeyt%iXfur@StS~Slihl g SSVcfsSSS bfe,~ere Sra'ttretatretfueated
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The RCS cold leg temperature limitation for starting an RCP is the same value as the LTOPS enable temperature to ensure that the basis of the heat injection transient is not violated. The Standard Technical Specifications (STS) prohibit starting an RCP when any RCS cold leg temperatures is less than or equal to the LTOPS enable temperature unless the secondary side water temperature of each steam generator is less than or equal to 50'F above each of the RCS cold leg temperatures.
3-9
System pressure based upon piping/structural analysis loads. The lower pressure extreme is specified by the reactor coolant pump P1 seal minimum differential pressure performance criteria. Uncertainties in the pressure and temperature instrumentation utilized by the LTOPS are accounted for consistent with the methodology of Reference 2.0. Accounting for the effects of instrumentation uncertainty imposes additional restrictions on the setpoint development, which is already based on conservative pressure limits such as a safety factor of 2 on pressure stress, use of a lower bound K,R curve and an assumed ~/iT flaw depth with a length equal to 1~8 times the vessel wall thickness.
3.3 Application of ASME Code Case N-514 ASME Code Case N-514<'" allows LTOPS to limit the maximum pressure in the reactor vessel to 110% of the pressure determined to satisfy Appendix G, paragraph G-2215, of Section XI of the ASME Godet'I. The application of ASME Code Case N-514 increases the operating margin in the region of the pressure-temperature limit curves where the LTOPS is enabled. Code Case N-514 also requires LTOPS to be effective at coolant temperatures less than 200'F or at coolant temperatures corresponding to a reactor vessel metal temperature, at a 1/4t distance from the inside vessel surface, less than RT>>~ + 50'F, whichever is greater. RTQQ7 is the highest adjusted reference temperature for weld or base metal in the beltline region at a distance one-fourth of the vessel section thickness from the vessel inside surface, as determined by Regulatory Guide 1.99, Revision 2.
The ability to use Code Case N-514 for establishing the LTOPS enable temperature is requested for approval by the NRC in the review of this PTLR methodology. However, at this time, no exemption has been submitted to apply the provisions of Code Case N-514 which would permit the pressure used to establish the LTOPS setpolnt to be based on 110% of the Appendix G limits.
3-7
Enclosure 2 to June 3, 1997 Letter Clarification of LTOP Boltu Tem erature Calculation Methodolo WCAP-14040-NP-A, Section 2.7 defines the minimum boltup temperature as 60'F. 10 CFR 50, Appendix G requires that the minimum boltup temperature be greater than or equal to the RTHD~ at the reactor vessel flange, which is -52'F for the Ginna Station reactor vessel.
The NRC interpretation of minimum boltup temperature is that the value must account for temperature instrument uncertainty, and thus using WCAP-14040-NP-A methodology, the boltup temperature would be 60'F plus temperature instrument uncertainty.
Since the actual requirement is 52 FI RG&E s limit of 60'F is considered to include significant (112'F) conservatism, which we consider to be much greater than any potential instrument uncertainty, and thus no additional uncertainty will be added.
Enclosure 3 Response to NRC Questions Concerning Previous LTOP Analysis
Provide a discussion of the dynamic and static head effects and how these were accounted for in the analyses for the mass addition and heat addition cases. For the dynamic head effect, consider the effect of all RCPs and RHR pumps that are allowed to operate. If you are limiting operation of such pumps in the LTOP region, provide a discussion of such controls.
The RELAP model used for the analysis automatically accounts for dynamic and static head effects. The pressure sensors for the LTOPs actuation are taken from the RCP suction leg volumes, consistent with their location in the plant. For Appendix G pressure limits the pressure is taken at the lowest downcomer mode in the reactor vessel. This results in the highest pressure in the reactor vessel and is therefore conservative. For RHR pressure, the highest pressure in the RHR system is used (pump discharge).
Cases chosen for the LTOPs analysis utilize running pumps consistent with the operating conditions, and conservatisms as described below.
Mass Addition Cases For the mass addition cases, three conditions are considered:
- 2. 3 Charging Pumps injecting with both RCPs running.
- 3. 1 Charging Pump injecting with one RCP running.
In all three mass addition cases, the RHR system is considered isolated. Isolation of the RHR system is conservative in that the RHR relief valve (designed to handle the full flowrate of 3 charging pumps) is isolated, and isolating the RHR system provides a smaller volume for the injected mass to expand into, thus resulting in a higher RCS pressure. Case 1 is run at 60'F and 212'F, bounding the conditions for which a vent can be established in the RCS. RCPs cannot be run when the RCS is vented. Case 2 is run for RCS temperatures above 135'F. Prior to going below 135'F (or conversely prior to going above 135'F on a heatup) two charging pumps and one RCP must be secured. Case 3 is run at 60'F to bound conditions between 60'F and 135'F. Results of these cases are attached.
Heat Addition For the heat addition cases, several scenarios were evaluated in order to determine the limiting cases, allowing adequate conservatism but not being unreasonably conservative which could result in unnecessary operation restrictions, as discussed below.
From an Appendix G standpoint not attaching the RHR system results in the most limiting pressure transient, since the RHR system would remove some of the heat being added from the start of an RCP. It was, however, necessary to model the RHR system in order to demonstrate adequate protection of the RHR system from overpressurization (assuming shutoff head for the RHR pumps for all cases while conservative would result in undesirable operating constraints). In'order'to ensure bounding conservatism for Appendix G, 'the heat exchangers were modeled as being inactive.
In order to determine the number of running RHR pumps, several sensitivities were run to determine minimum and maximum flowrates within the constraints of cooldown considering both minimum and maximum decay heat removal requirements. 'imits, The results indicate that for RCS temperatures below 280'F two RHR pumps may be in operation, above 280'F one pump would be in operation. Therefore the analyses assumes two pumps running for cases below 280'F, and one pump running above 280'F. The impact of these conditions on the transient is not significant since the pump curves for the RHR pumps is relatively flat.
t Additionally, it should be noted that the heat addition case was not considered in the original design basis for overpressurization protection of the RHR system.
Inadvertent start of an RCP takes several distinct actions by the operator which were not considered credible. Therefore, consideration of this transient for RHR overpressure protection is in and of itself added conservatism.
Justify the use of 85'F as the limiting low temperature for LTOP analyses (both heat and mass addition), in light of your curves extending to 60'F; or provide analyses at the lower value.
Transients were run at 85'F due to the fact that until recently curves were only available down to 85'F. Additional cases have been run at 60'I". For the heat addition cases utilizing a higher temperature for the initiating temperature results in a higher peak pressure. This is due to the fact that the change in density of water per degree fahrenheit increases as the temperature increases. For the mass addition case a lower temperature is more limiting, due to the higher density of the RCS liquid.
Again, the change in density is less that 0.5% and will have a negligible impact.
Results of these cases are attached.
Justify the use of 430 psig for PORV lift setpoint in the analysis. List the parameters that may affect this setpoint (e.g., Instrument uncertainty and others) and show that the proposed limit of 411 psig is sufficient to protect the Appendix G curves.
The analysis assumes a setpoint of 430 psig. It demonstrates, with this assumed setpoint, that all Appendix G limits are met (with margin). The instrument uncertainty for the actuation channels has been calculated to be 16.95 psig. When added to the proposed 411 psig limit, an acceptable analytical value of > 427.95 psig is arrived at. The analyzed 430 psig setpoint is therefore conservative.
The submittal indicates that instrument uncertainty need not be accounted for in Appendix G analyses. This in incorrect. Revise methodology to correct this statement.
The methodology document states that instrument uncertainty is accounted for (page 3.3 item q). The initial analysis done utilizing the methodology did account for instrument uncertainty, however a statement in the calculation was made that it did not need to be accounted for for Appendix G cases. This was consistent with the previously approved methodology. The current methodology requires instrument uncertainty to be accounted for and therefore all future analyses will account for it.
No revision to the methodology is required.
Justify the use of the RHR system for cooling in the heat addition analysis.
Discuss the effect of this configuration on the analysis in terms of differences in peale pressures that would be obtained had the.RHR system been assumed not operating.
See response to question 1. No credit is taken for cooling from the RHR system.
You assumed no RCS flow in the mass addition analysis. You must account for dynamic head effects for this analyses from both the RCPs and RHR pumps that may be operating. Did you account for the dynamic head effect separately?
See discussion in response to question 1.
In Section 6.2 you state that in the future you can credit the instrument uncertainty if needed. Instrument uncertainty must be accounted for.
Therefore, this statement is incorrect. Correct this statement in your methodology.
See discussion under question 4. Instrument uncertainty is included in the methodology and must be accounted for in all future analysis.
- 8. TS 3.5.3, "ECCS-MODE 4," requires that one train of ECCS be operable in Mode 4. This appears to be in conflict with the LTOP TS 3A.12 which required that all SI pumps be incapable of injecting into the RCS. Explain how Ginna meets these two TSs when in the LTOP region and in Mode 4.
See last paragraph of LCO bases for LCO 3.5.3 (page B3.5-26). Our ECCS requirements specify the capability of injection within 10 minutes which specifically addresses the need to place the SI pumps in pull-stop for LTOP.'S 3.4.12, "Low Temperature Overpressure Protection (LTOP) System," allows an SI pump to be capable of injecting into the RCS if the RCS is depressurized and an RCS vent of 1.1 square inches is established. Provide the analysis for this configuration with the new P/T curves.
Calculation of the pressure limit for the limiting mass addition cases when protection is provided by a 1.1 in'ent are provided in the updated LTOP analysis and results are attached.
Acceleration times for the RCPs are dependent upon pump loading, electrical system impedance, and voltage levels. For the LTOP heat addition cases a faster accelerating time results in more limiting transients since the heat addition occurs over a shorter time period.
A computer model (ETAP) was developed and benchmarked based on vendor pump performance curves and actual current, voltage, and power measurements taken during RCP starts during the 1991 and 1994 outages. Conservatisms employed in the model include:
Pum Loadin
- 1. The density of RCS fluid is taken at 350'F (lowest density) for all cases. This minimizes load and therefore results in a faster acceleration.
- 2. Flowrates were maximized in the RCS. Again, this decreases load and results in a faster acceleration.
S stem Im cdance
- 1. The offsite power impedance varies with changes in transmission system configuration. For the analysis, the configuration with the least impedance was used. A conservatively low impedance for this configuration was used.
S stem Volta e With Ginna Station off-line, the voltage level on the 4160V busses is reduced. A conservatively high voltage above measured voltages was chosen (4300V).
Utilizing the above conservatisms computer runs were made for all RCPs (A, B, Spare) with acceleration'times ranging from 17.4 to 18.6 seconds. For the LTOPs analysis the fastest acceleration, 17.4 seconds was chosen.
For the PORV, a stroke time of 1 second is chosen in the analysis. The acceptance criteria in periodic test procedure PT-2.6.5-SD specifies a maximum stroke time of 0.62 seconds. Actual stroke times recorded during the test have been consistently on the order of 0.5 seconds or less. Therefore, the analytical stroke time is conservative.
Attachment 1 LTOP Cases Summary of Results Type/Case RCS Temp, 'F ¹ of RCPs App G Limit, RV Peak, RHR limit, RHR Peak, running psia psia psia psia Mass Addition SI pump 60 554.7 414.8, 674.7 543.0 SI pump 212 710.7 396.3 674.7 525.3 3 Charging 135 594.7 588.0 674.7 664.0 1 Charging 60 554.7 554.3 674.7 656.4 Heat Addition RCP Start 60 1 start 554.7 551.3 674.7 650.0 RCP Start 280 1 start 1016.7 569.3 674.7 663.7 RCP Start 320 1 start 1391.7 563.8 674.7 655.7
Enclosure 4 Results of Revised LTOP Analyses
ROCHESTER GAS AND ELECTRIC CORPORATION Inter-Office Correspondence Ginna Station June 10, 1997
SUBJECT:
Approval of Vendor Technical Document "Low Temperature Overpressure Analyses for RG&E Ginna Plant" 51-1232641-00, "RGSE LTOP Analysis AIS" TO: File FTI No. 86-1234820-01 In accordance with Engineering Procedure QE-704, rev. 3, the purpose of this memorandum is to identify that the subject documents have been reviewed and are acceptable for use as the analysis of record for the Low Temperature Overpressure Protection System (LTOPS). Specifically:
The assumptions used in the calculation are appropriate for the Ginna Station with either Westinghouse Model 44 steam generators or BWI RSGs.
- 2. The transients selected are the correct limiting transients for the Ginna LTOPS design.
- 3. Since peak pressure for all transients is less than 800 psig; PORV tailpipe waterhammer is not a concern.
4 ~ The analysis is done for an LTOPS actuation setpoint of 430 psig. This allows sufficient margin from a nominal setpoint of 410 psig to account for instrument error.
- 5. A low pressure limit, to protect an RCP seal, cannot be accommodated by a single LTOPS setpoint without unacceptable high pressure results. Therefore, this criteria is waived.
Brian J lynn Manager, Primary Systems xc: Document Control RE Eliasz GT Wrobel