ML040160210
| ML040160210 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 01/16/2004 |
| From: | Leeds E NRC/NRR/DLPM |
| To: | Mccree V Division Reactor Projects II |
| mozafari B, NRR/DLPM, 415-2020 | |
| References | |
| FOIA/PA-2005-0103, TAC MC1305, TAC MC1306 | |
| Download: ML040160210 (7) | |
Text
January 16, 2004 MEMORANDUM TO: Victor M. McCree, Director Division of Reactor Projects Region II FROM:
Eric Leeds, Deputy Director /RA/
Division of Licensing Project Management Office of Nuclear Reactor Regulation
SUBJECT:
TASK INTERFACE AGREEMENT (TIA 2003-05); NRC POLICY QUESTIONS ON TECHNICAL SPECIFICATION ADEQUACY AND RELATED TECHNICAL SPECIFICATION OPERABILITY AT BRUNSWICK NUCLEAR PLANT (TAC NOS. MC1305 AND MC1306)
By letter dated November 12, 2003, you requested assistance from the Office of Nuclear Reactor Regulation to review and provide a policy position on three questions. These questions relate to the adequacy of the Technical Specification Table 3.3.5.1-1 allowable value for the condensate storage tank level - low function at the Brunswick Nuclear Plant.
These questions and our proposed responses are discussed in detail in the attached Safety Evaluation.
This completes our action under TAC Nos. MC1305 and MC1306.
Docket Nos. 50-325 and 50-324
Attachment:
As stated cc w/att: B. Platchek, R-I G. Grant, R-III K. Brockman, R-IV CONTACT: Brenda Mozafari 301-415-2020
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING TASK INTERFACE AGREEMENT 2003-05 NRC POLICY QUESTIONS ON TECHNICAL SPECIFICATION ADEQUACY AND RELATED TECHNICAL SPECIFICATION OPERABILITY CAROLINA POWER & LIGHT COMPANY BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 DOCKET NOS. 50-324 AND 50-325
1.0 INTRODUCTION
By letter dated November 12, 2003 (Reference 1), Region II requested that NRR review and provide a policy position on three questions. These questions relate to the adequacy of the Technical Specification (TS) Table 3.3.5.1-1 allowable value for the Condensate Storage Tank (CST) Level - Low function at Brunswick Nuclear Plant. The allowable value is the TS limiting trip setpoint value at which the high-pressure coolant injection (HPCI) pump suction will automatically transfer from its normal, non-safety-related source, the CST, to its safety-related source, the suppression pool. Region II inspectors identified that the licensees calculation of record supporting this allowable value did not adequately address potential air entrainment in the HPCI pump intake flow due to flow vortexes in the CST. In addition, the inspectors identified that the calculation included both analysis and measurement errors.
The licensee stated that there were no licensing or design-basis events that would result in a low CST level that would challenge the CST Level - Low function. The licensee also stated that the HPCI pump would not be running at its automatic flowrate of 4300 gpm with a low CST level because: 1) the TS-required suppression chamber water level - high function would activate first and would automatically transfer the HPCI pump suction from the CST to the suppression pool, or 2) operators could manually operate the HPCI pump with a low CST level, but would then manually stop the pump in response to a high reactor vessel water level before any entrained air would reach the pump. Consequently, the licensees operability determination stated: The Low CST level setpoint does not need to provide any protection for LOCA events.
It does provide protection when either an operator action in accordance with existing procedures, suppression pool level reduction is considered, or when early MSIV closure is not assumed. The licensee considered that the existing TS allowable value for the CST Level -
Low function was adequate and did not need to be changed.
It is the Region II position that the Updated Final Safety Analysis Report (UFSAR), TS Bases, original Brunswick safety evaluation report (SER), and the Standard Review Plan all indicate that the CST Level - Low function is to ensure the availability of the safety-related suction Attachment during the suction transfer. Based on this, the Region II conclusion is that the CST Level - Low suction transfer function needs to ensure that its design-basis requirements will be met regardless of the circumstances that call it into use. The design criteria does not appear to be dependent on any analysis of the sequence of licensing or design-basis events.
2.0 EVALUATION Technical Specification 3.3.5.1 of the Brunswick Nuclear Plant requires that the emergency core cooling system instrumentation for each Function in Table 3.3.5.1-1 shall be OPERABLE.
According to TS Table 3.3.5.1-1, Function 3.d, Condensate Storage Tank Level - Low is required to be OPERABLE in MODE 1, and MODES 2 and 3, with reactor steam dome pressure greater than 150 psig. If one or more channels are inoperable, Condition D would be entered immediately. Condition D requires that 1) the HPCI system be declared inoperable within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> from discovery of loss of HPCI initiation capability, and 2) the inoperable channel placed in trip or align the HPCI pump suction to the suppression pool within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The TS definition of OPERABLE is A system, subsystem, division, component, or device shall be OPERABLE or have OPERABILITY when it is capable of performing its specified safety function(s) and when all necessary attendant instrumentation, controls, normal or emergency electrical power, cooling and seal water, lubrication, and other auxiliary equipment that are required for the system, subsystem, division, component, or device to perform its specified safety function(s) are also capable of performing their related support function(s).
In order for the CST Level - Low function to be OPERABLE, the CST Level - Low instrumentation must be capable of performing its specified safety function(s). The specified safety functions of the CST Level - Low instrumentation are located in the TS Bases and the UFSAR. According to the TS Bases Section 3.3.5.1, the Condensate Storage Tank Level-Low signal is initiated from two level switches. The logic is arranged such that either level switch can cause the suppression pool suction valves to open and the CST suction valve to close.
The Condensate Storage Tank Level - Low Function Allowable Value is high enough to ensure adequate pump suction head while water is being taken from the CST. Section 9.2.6.2 (Revision 17) of the UFSAR states the following: For each tank, the HPCI and RCIC pumps take suction through a 16" line connected to the tank with a nozzle centerline 2' above the tank bottom. Level instruments will initiate an automatic transfer of the pumps suction path to the suppression pool suction if level approaches this connection. For HPCI the setpoint is above the 3.3' Tech Spec limit and below the 3.5' calibration maximum allowed value. To allow time for the suction transfer to take place, this setpoint provides a margin of approximately 10,000 gallons in the tank after the setpoint is reached and before air will be entrained in the process flow. Therefore, the specified safety functions of the CST Level - Low instrumentation is 1) to ensure adequate pump suction head while water is being taken from the CST, and 2) to initiate automatic transfer of the HPCI pump suction path to the suppression pool if level approaches the allowable value and before air is entrained into the process flow. If the TS allowable value is nonconservative with respect to the analysis assumption for air entrainment, the CST Level-Low instrumentation may not be capable of meeting its specified safety function.
Guidance for dealing with nonconservative TS is provided in NRC Administrative Letter 98-10 (Reference 2).
Region II requested that NRR review and provide policy positions on the following questions:
1.
Is it acceptable for the licensee to conclude that the CST Level - Low TS allowable value was adequate and did not need to be changed because only non-licensing/design-basis events would challenge the CST Level - Low function while the HPCI pump was operating at 4300 gpm? Or must the TS allowable value be adequate to protect the HPCI pump from damage if the CST level becomes low while the pump is operating at 4300 gpm, independent of the event required to reach this condition?
The condensate storage system provides a reserve supply of condensate to serve as the preferred source of water for the operation of the HPCI. As such, the HPCI is normally aligned to the CST. As summarized above, the TS Bases and the UFSAR state that CST Level - Low allowable value is high enough and provides a margin to ensure adequate pump suction head while water is being taken from the CST without air entrainment in the flow process. The CST Level - Low allowable value is independent of the event that caused the low level in the CST. Therefore, the licensee should evaluate whether the current TS allowable value is adequate to ensure that the automatic transfer from the CST to the suppression pool occurs at the appropriate CST level such that HPCI pump suction is maintained without air entrainment in the flow process. It is not appropriate for the licensee to assume that the CST Level - Low allowable value is adequate because only non-licensing/design-basis events would challenge the CST Level - Low function.
2.
Is it acceptable for the licensee to determine that the CST Level - Low function was operable because: 1) licensing/design-basis events would not challenge the function while the HPCI pump was operating in automatic at 4300 gpm, and 2) if operators were operating HPCI in manual with a low CST level, they would stop the pump before entrained air would reach the pump. Or should the operability determination have been based on the adequacy of the CST Level - Low function to protect the HPCI pump from damage if the CST level becomes low while the pump is operating at 4300 gpm, independent of the event required to reach this condition?
As stated above, the definition of OPERABLE refers to an SSCs capability of performing its specified safety function. The specified safety functions of the CST Level - Low instrumentation is 1) to ensure adequate pump suction head while water is being taken from the CST assuming an adequate allowable value, and 2) to initiate automatic transfer of the HPCI pump suction path to the suppression pool if level approaches the allowable value before air is entrained into the process flow. In addition, NRC Inspection Manual Part 9900 (Reference 3) states that in addition to providing the specified safety function, a system is expected to perform as designed, tested and maintained. Technical Specification 3.3.5.1 requires that Surveillance Requirements (SRs) 3.3.5.1.2, 3.3.5.1.4, and 3.3.5.1.5 be performed for the CST Level - Low function. These SRs provide the applicable testing mechanism for the CST Level-Low instrumentation and must be met to satisfy LCO 3.3.5.1. However, SRs alone may not demonstrate OPERABILITY.
The design of the CST Level - Low is described in the Brunswick UFSAR Section 9.2.6. In the event of low CST level, redundant safety grade level instrumentation has been provided to allow for the automatic transfer of the HPCI pump suctions from the CST to the suppression pool.
The setpoint allowable value ensures that the automatic transfer from the CST to the suppression pool will occur with sufficient water inventory available to the HPCI pump suction before air entrainment occurs in the process. The licensees calculation of record supporting this value did not adequately address the potential for air entrainment in the HPCI process flow due to vortexing in the CST. The calculated setpoint would not have precluded air entrainment.
Therefore, the licensees position that the CST Level - Low function is OPERABLE because the licensing/design-basis events would not challenge the function while the HPCI pump was operating in automatic at 4300 gpm does not demonstrate that the CST Level - Low instrumentation will perform its specified safety function.
The licensee also stated that the CST Level - Low function was OPERABLE because the operators would stop the pump before entrained air would reach the pump, if they were operating HPCI in manual with a low CST level. The CST Level - Low function is an automatic function. The NRC technical guidance (Reference 3) specifically states the licensees determination of operability with regard to the use of manual action must focus on the physical differences between automatic and manual action and the ability of the manual action to accomplish the specified function. The physical differences to be considered include, but are not limited to, the ability to recognize input signals for action, ready access to or recognition of setpoints, design nuances that may complicate subsequent manual operation such as auto-reset, repositioning on temperature or pressure, timing required for automatic action, etc.,
minimum manning requirements, and emergency operation procedures written for the automatic mode of operation. The licensee should have written procedures in place and training accomplished on those procedures before substitution of any manual action for the loss of an automatic action. Therefore, without the above-mentioned written procedures in place and training accomplished on the procedures, the licensee cannot demonstrate that the CST Level - Low function is TS OPERABLE while under manual operator action. In addition, the NRC technical guidance (Reference 3) continues to state that operator action in place of an automatic action is expected to be a temporary condition until the automatic action can be promptly corrected in accordance with 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action.
3.
May the licensee use 10 CFR 50.59 to add an operator action (without NRC approval) to assist the CST Level - Low function in protecting the HPCI pump from air entrainment (e.g., an operator action to manually reduce the HPCI flowrate if the CST water level becomes low)?
A licensee may use 10 CFR 50.59 to change procedures to add an operator action to assist the CST Level - Low function to protect the HPCI pump from air entrainment. However, the licensee may not use 10 CFR 50.59 to demonstrate TS OPERABILITY. As discussed in response to question 2, operator actions to assist the CST Level - Low function to protect the HPCI pump from air entrainment for TS OPERABILITY is expected to be a temporary condition with written procedures in place and training accomplished on the procedures.
3.0 REFERENCES
1.
McCree, V.M., USNRC, to E. Leeds, USNRC, Task Interface Agreement (TIA 2003-05);
NRC Policy Questions On Technical Specification Adequacy and Related Technical Specification Operability At Brunswick Nuclear Plant (Inspection Report 05000325, 05000324/03-08), November 12, 2003.
2.
NRC Administrative Letter 98-10: Dispositioning of Technical Specifications That Are Insufficient to Assure Plant Safety, December 29, 1998.
3.
NRC Inspection Manual Part 9900: Technical Guidance, Operable/Operability: Ensuring the Functional Capability of a System or Component, October 31, 1991.
Principal Contributor: Kerri Kavanagh, NRR Dated: January 16, 2004
January 16, 2004 MEMORANDUM TO: Victor M. McCree, Director Division of Reactor Projects Region II FROM:
Eric Leeds, Deputy Director /RA/
Division of Licensing Project Management Office of Nuclear Reactor Regulation
SUBJECT:
TASK INTERFACE AGREEMENT (TIA 2003-05); NRC POLICY QUESTIONS ON TECHNICAL SPECIFICATION ADEQUACY AND RELATED TECHNICAL SPECIFICATION OPERABILITY AT BRUNSWICK NUCLEAR PLANT (TAC NOS. MC1305 AND MC1306)
By letter dated November 12, 2003, you requested assistance from the Office of Nuclear Reactor Regulation to review and provide a policy position on three questions. These questions relate to the adequacy of the Technical Specification Table 3.3.5.1-1 allowable value for the condensate storage tank level - low function at the Brunswick Nuclear Plant.
These questions and our proposed responses are discussed in detail in the attached Safety Evaluation.
This completes our action under TAC Nos. MC1305 and MC1306.
Docket Nos. 50-325 and 50-324
Attachment:
As stated cc w/att: B. Platchek, R-I G. Grant, R-III A. Howell, R-IV CONTACT: Brenda Mozafari 301-415-2020 DISTRIBUTION:
NONPUBLIC/SENSITIVE PDII-2 R/F ELeeds EHackett AHowe EDunnington RPulsifer BMozafari KKavanagh PFredrickson, RII ADAMS ACCESSION NO.: ML040160210
- No major changes to SE OFFICE PDII-2/PM PDII-2/LA PDII-2/SC PDII/D NRR/DIPM DLPM/D D
NAME MChernoff for BMozafari EDunnington AHowe EHackett TBoyce ELeeds DATE 01/14/04 01/14/04 01/15/04 01/15/04 2/24/03 01/16/04 OFFICIAL RECORD COPY