ML042730116
| ML042730116 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 09/28/2004 |
| From: | Calvo J Office of Nuclear Reactor Regulation |
| To: | Barrett R Office of Nuclear Reactor Regulation |
| References | |
| TAC MC4286, TAC MC4287, TIA 2004-02 | |
| Download: ML042730116 (9) | |
Text
September 28, 2004 NOTE TO: Richard J. Barrett FROM: José A. Calvo ( /RA by JACalvo )
SUBJECT:
D.C. COOK UNITS 1 AND 2: BACKFIT DETERMINATION FOR THE STAFF RESPONSE TO TASK INTERFACE AGREEMENT (TIA) 2004-02 (DEGRADED VOLTAGE PROTECTION) (TAC NOs. MC4286 & MC4287)
- Rich, On September 28, 2004, I concurred on the memorandum (ADAMS ACCESSION NO.
ML042680384) that represents Electrical & Instrumentation and Controls Branch (EEIB) findings using Appendix B, of Office Instruction No. LIC-202, Procedures for Managing Plant Specific Backfits and 50.54(f) Information Requests. These findings conclude that the staff response to TIA 2004-02 are not backfits. We would like the opportunity to discuss this matter with you further before seeking your concurrence on the subject memorandum.
A preliminary conditional core damage probability (CCDP) of 2.2E-01 was derived for the loss of function case assuming that the degraded voltage condition disables both emergency core cooling system (ECCS) trains. Therefore, we encourage an expedited schedule for resolution of these issues. A member of my staff will be making arrangements for a detailed discussion of the issues surrounding this matter at your convenience.
cc: RVJenkins EEIB R/F ASGill
September 28, 2004 NOTE TO: Richard J. Barrett FROM: José A. Calvo ( /RA by JACalvo )
SUBJECT:
D.C. COOK UNITS 1 AND 2: BACKFIT DETERMINATION FOR THE STAFF RESPONSE TO TASK INTERFACE AGREEMENT (TIA) 2004-02 (DEGRADED VOLTAGE PROTECTION) (TAC NOs. MC4286 & MC4287)
- Rich, On September 28, 2004, I concurred on the memorandum (ADAMS ACCESSION NO.
ML042680384) that represents Electrical & Instrumentation and Controls Branch (EEIB) findings using Appendix B, of Office Instruction No. LIC-202, Procedures for Managing Plant Specific Backfits and 50.54(f) Information Requests. These findings conclude that the staff response to TIA 2004-02 are not backfits. We would like the opportunity to discuss this matter with you further before seeking your concurrence on the subject memorandum.
A preliminary conditional core damage probability (CCDP) of 2.2E-01 was derived for the loss of function case assuming that the degraded voltage condition disables both emergency core cooling system (ECCS) trains. Therefore, we encourage an expedited schedule for resolution of these issues. A member of my staff will be making arrangements for a detailed discussion of the issues surrounding this matter at your convenience.
cc: RVJenkins EEIB R/F ASGill ADAMS/ACCESSION No.: ML042730116
MEMORANDUM TO: T. Marsh, Director Division of Licensing Project Management FROM: Jose A. Calvo, Chief Electrical & Instrumentation and Controls Branch Division of Engineering
SUBJECT:
D.C. COOK 1 AND 2: A BACKFIT DETERMINATION FOR THE STAFF RESPONSE TO TIA 2004-02 (DEGRADED VOLTAGE PROTECTION)
The Electrical & Instrumentation and Controls Branch (EEIB) finds using Appendix B, of Office Instruction No. LIC-202, Procedures for Managing Plant Specific Backfits and 50.54(f)
Information Requests, that the staff positions listed in Reference (1) are not backfit positions for the Donald C. Cook (CNP) nuclear plant. A review of the original licensing documents for the CNP degraded voltage protection system indicates that the protective features were to be immediately available and in force during normal operation. Specifically, the subject staff positions regarding the existing design at D.C. Cook are:
- 1. The automatic degraded voltage protection should not be bypassed during normal operation. CNP does not meet the design criteria for degraded voltage protection stated in the Generic Letter dated June 3, 1977, (MPA B-23) that was part of the plants current licensing basis.
- 2. A delay of 30 seconds before the buses are transferred from unit auxiliary transformer (UAT) to the reserve auxiliary transformer is not in conformance with the plants current licensing basis.
The basis for the subject determination is described in the Attachment. A preliminary conditional core damage probability (CCDP) of 2.2E-01 was derived for the loss of function case assuming that the degraded voltage condition disables both emergency core cooling system (ECCS) trains. Therefore, we encourage an expedited schedule for resolution of these issues. Listed below are recommendations for the disposition of the matter using other regulatory processes.
Background:
On July 11, 2003, the NRC completed the safety system design and performance capability biennial baseline inspection at CNP. During the inspection, the inspectors identified that the degraded voltage protection scheme was bypassed whenever the 4160V buses were not being supplied through the reserve auxiliary transformers (RATs). This resulted in a lack of automatic degraded voltage protection during normal operation, and for the first 30 seconds of an accident when engineered safety feature (ESF) loads were being sequenced onto the safety buses.
CONTACT: N. Trehan, NRR/EEIB Paul Gill, NRR/EEIB 415-2777 415-3316
By letter dated June 7, 2004, Region III requested NRR assistance through Task Interface Agreement (TIA) 2004-02 (Reference 2) to evaluate the lack of automatic degraded voltage protection during normal operation when power is supplied through the unit auxiliary transformers (UATs), and during design basis events for the first 30 seconds when degraded voltage protection scheme is bypassed.
Section B of the Electrical & Instrumentation and Control Branch evaluated the Region III concerns regarding the degraded voltage protection design at D.C. Cook and concluded Staff Positions 1 and 2 as stated above.
Recommendations:
(1) Staff Position 1 should be addressed through normal enforcement processes.
(2) Staff Position 2 derives from a fact not being disclosed by the CNP (the licensee). In addition to enforcement processes, the Office of Investigation (See NRR Office Instruction COM-105) may consider this matter to determine whether any wrongdoing had been committed by the licensee. Wrongdoing is defined in Management Directive 8.8 as an intentional violation of regulatory requirements or a violation resulting from careless disregard of, or reckless indifference to regulatory requirements. The Attachment provides additional information on this matter.
References:
- 1. Memorandum from R. Jenkins, EEIB to L. Raghavan, DLPM, D.C. COOK 1 AND 2:
REQUEST FOR TECHNICAL ASSISTANCE ON DEGRADED VOLTAGE PROTECTION (TAC NOS. MC3428 & MC3429) ADAMS ACCESSION No.
- 2. Memorandum from C. D. Pederson, Region III to E. J. Leeds, DLPM, REQUEST FOR TECHNICAL ASSISTANCE ON DEGRADED VOLTAGE PROTECTION AT D. C.
COOK (TIA 2004-02)
Attachment:
As stated
By letter dated June 7, 2004, Region III requested NRR assistance through Task Interface Agreement (TIA) 2004-02 (Reference 2) to evaluate the lack of automatic degraded voltage protection during normal operation when power is supplied through the unit auxiliary transformers (UATs), and during design basis events for the first 30 seconds when degraded voltage protection scheme is bypassed.
Section B of the Electrical & Instrumentation and Control Branch evaluated the Region III concerns regarding the degraded voltage protection design at D.C. Cook and concluded Staff Positions 1 and 2 as stated above.
Recommendations:
(1) Staff Position 1 should be addressed through normal enforcement processes.
(2) Staff Position 2 derives from a fact not being disclosed by the CNP (the licensee). In addition to enforcement processes, the Office of Investigation (See NRR Office Instruction COM-105) may consider this matter to determine whether any wrongdoing had been committed by the licensee. Wrongdoing is defined in Management Directive 8.8 as an intentional violation of regulatory requirements or a violation resulting from careless disregard of, or reckless indifference to regulatory requirements. The Attachment provides additional information on this matter.
References:
- 1. Memorandum from R. Jenkins, EEIB to L. Raghavan, DLPM, D.C. COOK 1 AND 2:
REQUEST FOR TECHNICAL ASSISTANCE ON DEGRADED VOLTAGE PROTECTION (TAC NOS. MC3428 & MC3429) ADAMS ACCESSION No.
- 2. Memorandum from C. D. Pederson, Region III to E. J. Leeds, DLPM, REQUEST FOR TECHNICAL ASSISTANCE ON DEGRADED VOLTAGE PROTECTION AT D. C.
COOK (TIA 2004-02)
Attachment:
As stated DISTRIBUTION:
JACalvo EEIB R/F JLamb ADAMS/ACCESSION No.: ML042680384 OFFICE EEIB:DE:NRR EEIB:DE:NRR SC:EEIB:DE:NRR BC:EEIB:DE:NRR NAME NKTrehan ASGill RVJenkins JACalvo DATE 09/27/04 09/27/04 09/ /04 09/28/04 OFFICE SECY:EEIB:DE:NRR PM:DLPM:NRR SC:DLPM:NRR D:DE:NRR NAME BParham CLyon LRaghavan RBarrett DATE 09/ /04 09/ /04 09/ /04 09/ /04 OFFICIAL RECORD COPY
Bases For Backfit Determination Regarding Staff Response to TIA 2004-02 Introduction Appendix B, of Office Instruction No. LIC-202, Procedures for Managing Plant Specific Backfits and 50.54(f) Information Requests, (Reference 1) Section C, (1) (c) states that the technical staff should evaluate the potential backfit to determine whether or not the proposed staff position in fact constitutes a backfit.
- The technical staff performing the review should reference NRC rules, licensee commitments, licensing basis for the plant, and other appropriate guidance documents to provide the basis for the backfit determination. The staff should not address the technical ramifications of the issue in the determination.
Appendix, Guidance for Making Backfit Determinations, of Management Directive 8.4, NRC Program for Management of Plant-Specific Backfitting of Nuclear Plants, (Reference 2) provides the following criteria for determining whether a staff position is or is not a backfit:
Reanalysis of Issues - Throughout plant lifetime, many individuals on the NRC staff have an opportunity to review the requirements and commitments incumbent upon a licensee. Undoubtedly, there will be occasions when a reviewer concludes the licensee's program in a specific area does not satisfy a regulation, license condition or commitment. In the case where the staff previously accepted the licensee's program as adequate, any staff specified change in the program would be classified as a backfit.
For example, in the case of an NTOL, once the SER is issued signifying staff acceptance of the programs described in the SAR, the licensee should be able to conclude that his commitments in the SAR satisfy the NRC requirements for a particular area. If the staff was to subsequently require that the licensee commit to additional action other than that specified in the SAR for the particular area, such action would constitute a backfit. In addition, If a licensee has implemented a technical resolution intended to meet an applicable regulatory staff position, and staff for an extended period simply allows the licensee resolution to stand with tacit acceptance Indicated by non-action on the part of NRC, then a subsequent action to change the licensee's design, construction, or operation is a backfit.
Therefore, the question to be addressed is whether a reanalysis of an issue exists based upon the regulatory development of the current licensing basis at Donald C. Cook nuclear plant (CNP).
ATTACHMENT
Regulatory Analysis General Design Criterion (GDC) - 17, Electric Power System, of Appendix A, General Design Criterion for Nuclear Power Plants, to 10 CFR Part 50 requires that nuclear power plants have an onsite electric power system and an offsite electric power system to permit the functioning of structures, systems and components important to safety. The safety function of each system (assuming the other system is not functioning) is to provide sufficient capacity and capability to assure that (1) fuel design limits and design conditions of the reactor coolant boundary are not exceeded as a result of anticipated operational occurrences and (2) the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents. The onsite electric power supplies (including the batteries) and the onsite electric distribution system is required to have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure. Electric power from the transmission network to the onsite electric distribution system is required to be supplied by two physically independent circuits designed and located so as to minimize the likelihood of their simultaneous failure. In addition, GDC 17 requires provisions to minimize the probability of losing electric power from the remaining electric power supplies as the result of loss of power from the unit, the offsite transmission network, or the onsite power supplies.
10 CFR 50.36, Technical Specifications, requires the technical specifications (TS) to be derived from the analyses and evaluation included in the safety analysis report. A TS limiting conditions for operation (LCOs) is required to be established for each structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier. LCOs specify minimum requirements for ensuring safe operation of the unit. Surveillance Requirements (SRs) are requirements, included as part of TS, to assure that the necessary quality of systems and components are maintained and LCOs will be met. When an LCO is not met, due to one condition such as either a component failure or maintenance outage, action is required within a specified time by the TS to fix the condition by restoring required equipment to an operable condition.
Design Considerations An electric power system design (pursuant with GDC 17) includes offsite and onsite electric power systems to permit functioning of structures, systems, and components important to safety. To support these systems, the design, also, includes loss of power instrumentation (degraded voltage protection) and automatic load sequencer systems.
The typical design also includes loss of power instrumentation and automatic load sequencer support systems associated with each ac system division. The primary function of the loss of power instrumentation system is to assure the independence between offsite and onsite systems. This independence, pursuant with GDC 17 of 10 CFR Part 50, Appendix A, minimizes the probability of losing electric power from the onsite electric supplies as a result of, or coincident with, the loss of power from the transmission network. Loss of power instrumentation also supports independence between redundant ac systems and with the automatic load sequencer assures the capacity and capability of the offsite and onsite ac power supplies and the ac system load group.
Evaluation Staff Position 1: The automatic degraded voltage protection should not be bypassed during normal operation. CNP does not meet the design criteria for degraded voltage protection stated in the Generic Letter dated June 3, 1977, (MPA B-23) that was part of the plants current licensing basis.
Discussion:
The original design (July 22, 1977 letter) for degraded voltage protection proposed by CNP (the licensee) featured a design where the safety buses would not be protected while being supplied by the UATs. The proposed design used undervoltage relays on the high side of the 34.5kV/4.16kV RATs in order to monitor the offsite power supply directly. The licensee position was that degraded voltage protection was only required when the unit was connected to the offsite source. Therefore, the degraded voltage relays mounted on the 4160V safety buses only provide a trip function when the buses are supplied by the RAT. The NRC rejected this proposal and required the degraded voltage relays to monitor the 4160V safety busses citing the 1997 NRC Generic Letter, which required the design of the voltage monitors to comply with IEEE-279-1971. The letter stated that the intent of the position was that the monitors of the undervoltage protection system for ESF loads were a part of the Class 1E distribution system.
In response to the staff determination that undervoltage monitors be part of the Class 1E system, the licensee modified the design to have voltage monitors on the 4160V safety buses, but only provided a trip function when the buses were supplied by the RAT. The staff was not aware of this aspect of the design and did not review the existing degraded voltage protection scheme with respect to the bypassing of degraded voltage protection function during normal operation. It should be noted that the licensee did not inform the staff that these relays were disabled during normal operation in their original modification which installed the voltage monitors on the 4160V safety buses.
The staff learned the significance of this distinction when it was stated explicitly in Technical Specifications change request AEP:NRC 1063, dated November 28, 1988, as follows, Please note that the function of the Degraded Voltage relays is to disconnect the plant from the grid for a sustained degraded voltage condition. These relays are armed only when the plant is fed from offsite power and not normally active during unit operation. The NRC took note of the licensees 1988 statement in the cover letter to Amendment Nos. 137 and 124 to License Nos.
DPR-58 and DPR-74, dated May 25, 1990. The NRC stated that the design was not in conformance with Standard Review Plan (SRP), Chapter 8, Appendix 8A, Branch Technical Position PSB #1 and recommended that the degraded voltage relays remain in force regardless of the power sources connected to the safety busses; i.e., whether powered by the unit auxiliary transformer or the off-site power system.
Therefore, the staff position is not a reanalysis of this issue because prior applicable staff positions clearly indicate disagreement with the licensees position. The subject staff position is not a backfit.
Staff Position 2: A delay of 30 seconds before the buses are transferred from unit auxiliary transformer (UAT) to the reserve auxiliary transformer are not in conformance with the plants current licensing basis.
Discussion:
The staff first became aware that the degraded voltage protective function was not active for the critical first 30 seconds of an accident after the Region III safety system design and performance capability biennial baseline inspection completed on July 11, 2003 (Reference 3).
A review of the records related to the staff approval of the degraded voltage protection system at CNP failed to reveal any disclosure by the licensee of the designed 30 second time delay.
Therefore, with the existing design the degraded voltage conditions will not be automatically detected during the first 30 seconds of an accident and the permanently connected Class 1E loads (e.g., magnetic contractors for the motor operated valves) could be damaged and prevent the associated motors from performing their safety functions. The damage to the contractors may result in blowing of the control transformer fuses or burning of the control power transformers. While supplying power from the UAT to the safety buses, the degraded conditions may result from deficiencies in the equipment between the main generator and the safety buses, or by the starting transients experienced during normal operating events not originally considered in sizing of the these circuits, or problems with the main generator and its excitation system. Therefore, the existing design of the degraded voltage protection is not adequate for assuring plant safety because it may render both offsite and onsite power sources inoperable and may also disable redundant safety loads from being connected to either the offsite or onsite power system and thus resulting in the loss of function. A preliminary CCDP of 2.2E-01 was derived for this loss of function case assuming that the degraded voltage condition disables both ECCS trains (except auxiliary feedwater turbine driven pumps). This design was not described by the licensee in its response to MPA B-23 or in its Final Safety Evaluation Report (FSAR).
In addition, in the letter from J. Tillinghast, Indiana and Michigan Electric Company to E. G.
Case, NRR dated July 22, 1977, (Reference 4) states that The Technical Specifications Engineered Safety Features Response Time Table (Table 3.3-5, Section 3/4 pp. 3-27 through 3-30) lists maximum allowable response times for the Safety Injection and other Engineered Safety Features for several different initiating signals. The 2 second time delay of the second level undervoltage scheme can be accommodated without exceeding the postulated maximum allowable response time. The staff relied on that statement in its approval of CNPs degraded voltage protection function (Reference 5). There is no record of a similar licensee evaluation for the 30 second time delay.
Based on the above facts it is not credible the staff would ignore the safety implications associated with the 30 seconds delay if this information was disclosed by the licensee.
Therefore, the staff position is not a reanalysis of this issue due to the incompleteness of the information originally provided to the staff. The subject staff position is not a backfit.
Conclusion Based upon the above information the staff concludes that Staff Positions 1 and 2 are not backfits and further action should be conducted under normal enforcement processes. Given the failure to disclose a material fact important to safety as discussed in Staff Position 2, this matter should be referred to the Office of Investigations for further action.
References:
- 1. Office Instruction No. LIC-202, Procedures for Managing Plant Specific Backfits and 50.54(f) Information Requests
- 2. Management Directive 8.4, NRC Program for Management of Plant-Specific Backfitting of Nuclear Plants
- 3. Donald C. Cook Nuclear Power Plant, Units 1 and 2 NRC Inspection Report No.
50-315/03-07(DRS); 50-316/03-07(DRS) (ADAMS Accession No. ML032260201)
- 4. Letter from J. Tillinghast, Indiana and Michigan Electric Company to E. G. Case, NRR dated July 22, 1977
- 5. Amendment No. 39 to Facility Operating License No. DPR-58; dated July 25, 1980.