ML18011A343
| ML18011A343 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 02/14/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18011A341 | List: |
| References | |
| NUDOCS 9403020073 | |
| Download: ML18011A343 (8) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAF Y EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO 42 TO FACIL Y OPERATING LIC ~GNO NPF 63 CA OLINA POWER
& LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT UNIT 1 DOCKET NO. 50-400
- 1. 0 INTRODUCTION By [[letter::HNP-93-821, Application for Amend to License NPF-63,proposing Changes Incorporating AFW Sys TS 3.7.1.2 Surveillance Subparagraph b.1 Revised Capabilities of AFW Initiation Signal|letter dated July 26, 1993]], Carolina Power
& Light Company (CP&L or the licensee) submitted a request for changes to the Shearon Harris Nuclear Power Plant (SHNPP) Technical Specifications (TS).
The request would change a
requirement associated with the auxiliary feedwater (AFW) system and change TS'urveillance Requirement 4.7. 1.2. 1, in accordance with the revised capabilities of the AFW system design.
The licensee also revised the associated Bases section of the TS to incorporate the new design capabilities.
The AFW system, in addition to its emergency system function, also serves as an alternate to the feedwater system during the hot shutdown and cooldown operations.
The AFW system can also be used to adjust steam generator (SG) water level prior to and during plant start-up and to establish and maintain wet lay-up conditions in the SGs.
The current TS surveillance requirements limit the ability to utilize the AFW system for these operations.
Therefore, the licensee proposed to modify the AFW system design which will allow the TS changes needed for this flexibility.
- 2. 0 EVALUATION The proposed amendment involves three specific changes to (1) allow the testing of the AFW flow control valves (FCVs) new auto-open design feature, (2) delete the periodic surveillance testing of the auto-close feature for the AFW motor-driven pump reci}culation line valves; and (3) revise the general description of the new AFW Bases to reflect the surveillance requirements.
The following is the staff's evaluation:
- 2. 1 New a o-o en desi n feature for AFW Flow Control Valves.
The AFW system serves as a backup system for supplying feedwater to the secondary side of the SGs at times when the normal feedwater system is not available, thereby maintaining the heat sink capabilities of the SG during start-up, hot standby, and cooldown, and also functions as an engineered'afety system.
In the latter function, the AFW system is directly relied on to prevent core damage in the event of a transient, such as loss of normal feedwater or a secondary system pipe rupture with a loss of offsite power, by cooling the reactor coolant system to the residual heat removal system entry temperature of 350 degrees F.
The system consists of two 100 percent capac Ity motor-driven pumps and one 200 percent capacity turbine driven pump.
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motor-driven supply and the turbine driven supply for each of the three SGs are connected
- together, and a
common line for each SG carries the water through the steam and feedwater pipe tunnel into containment and connects to the AFW nozzle on each SG.
Each AFW supply line from the motor-driven AFW pump discharge header to its respective SG contains a safety Class 2 motor-operated AFM isolation valve in series with a safety Class 3 electro-hydraulic operated FCV.
Each turbine driven pump steam generator supply line contains a
safety Class 2, normally open, DC-powered motor-operated AFW isolation valve in series with a safety Class 3, electro-hydraulic, DC-operated FCV.
The motor-driven AFW pumps and their associated systems will be used for feedwater supply to the SGs during startup, hot standby, or shutdown.
The turbine driven pump and its associated
- piping, up to the normally closed supply
- valves, are not used during normal operation,
- startup, hot standby or normal shutdown.
The current TS surveillance requirements limit the ability to utilize the AFM system during startup, hot standby, or shutdown operations by requiring the FCVs to be fully open rather than allowing operation at some intermediate or throttled position consistent with a controlled evolution such as filling a SG to a wet lay-up condition.
The licensee has proposed a modification to the control logic for the three FCVs located on the AFW discharge line from the motor-driven AFW pumps to their respective SGs (one valve in each line) so they will automatically open upon receipt of an AFM initiation signal.
Incorporation of this auto-open signal into the control logic for these FCVs will provide a system design whereby, regardless of each valve.'s position, they will automatically open on an AFW initiation signal.
Thus, this change will allow the AFW system to be fully capable of automatically responding to an auto-start demand while at the same time be utilized as an alternate to the main FW system during plant Node I, 2, or 3.
The auto-open logic will be designed in such a way that it will not affect the isolation of the faulted SG in the event of a steam line or main FM pipe break.
The isolation signal which closes the FCVs for isolation purposes will override the AFW actuation signal.
In addition, the new design will still allow isolation of a faulted steam generator in the event of a steam line or main feedwater pipe break, by configuring the AFW isolation signal to override the AFW actuation signal and to close the affected FCVs.
On the basis of the proposed modification to the AFW FCVs automatic opening
- feature, the licensee proposed removal of these valves from TS Surveillance Requirement 4.7. 1.2. l.a.3, which requires "verification by flow or position check that each valve (manual, power-operated, or automatic) in the flow path that is not locked,
- sealed, or otherwise secured in position is in its correct position...."
With the proposed design
- change, these FCVs will no longer have a correct position that would require verification.
Additionally, the licensee proposed to change TS Surveillance Requirement 4.7. 1.2. l.b. l to read as follows:
Verifying that each motor-driven auxiliary feedwater pump starts automatically, as designed, upon receipt of a test signal and that the respective pressure control valve for each motor-driven pump and each flow control valve with an au'to-open feature respond as required;
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This new surveillance requirement incorporates the new logic design in each FCV with an auto-open feature that will respond as required to a test signal every 18 months during shutdown.
The time interval for testing the FCVs is consistent with the time interval for other engineered safety equipment.
Based on the above review, the staff finds the proposed new design of the AFW control system and the proposed TS changes meet the intent of the Standard Review Plan for the AFW system in that the initiating signal will start all AFW pumps and supporting
- systems, align the AFW sources, and open flow paths from the AFW pumps to the steam generators, while still allowing the ability to isolate or terminate AFW flow to a depressurized steam generator.
Therefore, the proposed changes are acceptable.
2.2 FW Motor-Driven Pum Recirculation Va ves.
The licensee also proposed changes to Surveillance Requirement 4.7. 1.2. l.b. 1 to delete the periodic surveillance testing of the auto-close feature for the AFW motor-driven pump recirculation line isolation valves.
The auto-close feature of each motor-driven AFW pump recirculation line isolation valve closes a running AFW pump's recirculation line valve if the other train's safety bus is de-energized.
This feature was needed to ensure the minimum AFW flow rate of 475 gpm for the loss-of-normal feedwater event.
The licensee has performed a reanalysis of the event and determined that 430 gpm is a
satisfactory AFW flow rate.
Based on the 430 gpm AFW flow rate, the auto closure of the recirculation line isolation valve is no longer required.
The staff has previously reviewed and approved the results of the reanalysis regarding the AFW flow rate (License Amendment No. 29, dated September 2,
1992, incorporated the results of the reanalysis regarding the AFW flow delivery rate of 430 gpm into Technical Specification 3.7. 1.2.)
Therefore, since the AFW pumps can now achieve the required flow rate with its recirculation lines remaining open, automatic closure of the motor -driven AFW pump recirculation line valves is no longer necessary.
This change will allow more reliable operation of the AFW pumps since the recirculation lines will never have to be shut, providing cooling to the pumps under all operating conditions.
Therefore, the proposed change is acceptable.
2.3 Tec nical S ecif'cat o
Bases 3 4.7. 1.2 for t e AFW S ste The licensee proposed a revision to the Bases for the AFW system to reference the AFW pump performance curves instead of referring to a single system flowrate.
The staff found the revised Bases to be consistent with the system description and the safety function presented in the plant Final Safety Analysis Report (FSAR).
3.0
SUMMARY
The staff finds the proposed changes to the TS and Bases to be acceptable.
The proposed TS changes, revisions to the AFW system surveillance requirements, and the plant design changes upon which they are based are consistent with the intent of the Standard Review Plan, Section 10.4.9, AFW System for Pressurized Water Reactors, and do not adversely affect the systems
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ability to function as an engineered safety feature system to prevent core damage during FSAR, Chapter 15, analyzed transients including loss of main feedwater, steam line rupture, and feedwater line rupture.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the State of North Carolina official was notified of the proposed issuance of the amendment.
The State official had no comments.
5.0 ENVIRONM NTAL CONSIDERATION The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes the Surveillance Requirements.
The NRC staff has determined that the amendment involves no significant incr ease in the amounts, and no significant change in the types, of any effluents that may be released
- offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a
proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (58 FR 46225).
Accordingly, the amendment meets the eligibilitycriteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0
~CONC USIO The Commission has concluded, based on the considerations discussed
- above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed
- manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
C. Hayberry H. Garg Date:
February 14, 1994
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