ML061090107
| ML061090107 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 04/17/2006 |
| From: | Travers W D Region 2 Administrator |
| To: | Stall J A Florida Power & Light Co |
| References | |
| EA-06-027, IR-06-010 | |
| Download: ML061090107 (11) | |
Text
April 17, 2006EA-06-027 Florida Power and Light CompanyATTN:Mr. J. A. Stall, Senior Vice PresidentNuclear and Chief Nuclear Officer P. O. Box 14000Juno Beach, FL 33408-0420
SUBJECT:
FINAL SIGNIFICANCE DETERMINATION FOR A WHITE FINDING ANDNOTICE OF VIOLATION (Turkey Point Nuclear Plant - NRC Inspection ReportNo. 05000250,251/200610)
Dear Mr. Stall:
The purpose of this letter is to provide you with the Nuclear Regulatory Commission's (NRC)final significance determination for a finding involving the B auxiliary feedwater (AFW) pumpthat was determined to be inoperable due to an incorrectly installed bearing. The finding was documented in NRC Inspection Report No. 05000250,251/2005005 dated January 27, 2006,and was assessed under the significance determination process as a preliminary White issue (i.e., an issue of low to moderate safety significance which may require additional NRC inspection). The cover letter to the inspection report informed Florida Power and Light Company (FPL) of the NRC's preliminary conclusion, provided FPL an opportunity to request aregulatory conference on this matter, and forwarded the details of the NRC's preliminaryestimate of the change in core damage frequency for this finding.In lieu of a regulatory conference, FPL provided a written response dated March 13, 2006. FPL's assessment identified several plant-specific factors beyond those used in the NRC'spreliminary estimate and concluded that the finding was of very low risk significance (Green).
In summary, the plant-specific factors included the time dependent degradation of the B AFW pump, more recent industry generic failure data, and additional and diverse plant specific features for secondary side heat removal.After considering the information developed during the inspection and the information FPLprovided in its written response, the NRC has concluded that the final inspection finding isappropriately characterized as White in the mitigating systems cornerstone. In summary, theNRC's risk assessment concluded that the factors identified in FPL's written response ofMarch 13, 2006, were insufficient to warrant a significant change in our preliminary risk estimate. Additional information on the NRC's risk estimate, including the disposition of thosefactors identified in FPL's written response, are included as Enclosure 2 to this letter.You have 10 business days from the date of this letter to appeal the staff's determination ofsignificance for the identified White finding. Such appeals will be considered to have merit onlyif they meet the criteria given in NRC Inspection Manual Chapter 0609, Supplement 3.The NRC has also determined that the finding represents a violation of TechnicalSpecification 3.7.1.2 and 10 CFR Part 50, Appendix B, Criterion XVI. In this case, the B AFW Florida Power and Light Company2pump was inoperable from approximately September 10, 2003, until November 7, 2005, due toan incorrectly installed bearing. In addition, FPL failed to identify and correct the condition of the pump during this time period as required by 10 CFR Part 50, Appendix B, Criterion XVI, despite several indicators that the pump was degraded. The violation is cited in the attachedNotice of Violation (Notice), and the circumstances surrounding it are described in detail in NRC Inspection Report No. 05000250,251/2005005. In accordance with the NRC EnforcementPolicy, the Notice is considered escalated enforcement action because it is associated with a White finding.Because plant performance for this issue has been determined to be in the regulatory responseband, we will use the NRC Action Matrix to determine the most appropriate NRC response forthis event. We will notify you, by separate correspondence, of that determination.You are not required to respond to this letter unless the description herein does not accuratelyreflect your position, or if you choose to provide additional information. For administrative purposes, this letter is issued as a separate NRC Inspection Report (Nos. 05000250,251/2006010) and the above violation is identified as VIO 05000250,251/2006010-01, White Finding - AFWPump B out of Service Greater than TS Allowed Due to Incorrect Bearing Installation. Accordingly, Apparent Violation (AV) 05000250,251/2005005-02 is closed.In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, itsenclosures, and your response (should you choose to provide one) will be made availableelectronically for public inspection in the NRC Public Document Room or from the NRC's document system (ADAMS) which is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html. To the extent possible, any response should notinclude any personal privacy, proprietary, classified, or safeguards information so that it can be made available to the Public without redaction. The NRC also includes significant enforcementactions on its Web site at www.nrc.gov; select What We Do , Enforcement , then SignificantEnforcement Actions
.Should you have any questions regarding this letter, please contact Mr. Charles A. Casto,Director, Division of Reactor Projects, at (404)562-4500.Sincerely,/RA/William D. Travers Regional AdministratorDocket Nos. 50-250, 50-251License Nos. DPR-31, DPR-41
Enclosures:
- 2. NRC Evaluation of Risk Significant Factorscc w/encls: (See next page)
Florida Power and Light Company3cc w/encls
- T. O. Jones Site Vice President Turkey Point Nuclear Plant Florida Power and Light Company 9760 SW 344th Street Florida City, FL 33035Walter ParkerLicensing Manager Turkey Point Nuclear Plant Florida Power and Light Company 9760 SW 344th Street Florida City, FL 33035Michael O. PearcePlant General Manager Turkey Point Nuclear Plant Florida Power and Light Company 9760 SW 344th Street Florida City, FL 33035Mark Warner, Vice PresidentNuclear Operations Support Florida Power & Light Company P. O. Box 14000 Juno Beach, FL 33408-0420Rajiv S. KundalkarVice President - Nuclear Engineering Florida Power & Light Company P. O. Box 14000 Juno Beach, FL 33408-0420M. S. Ross, Managing AttorneyFlorida Power & Light P. O. Box 14000 Juno Beach, FL 33408-0420
_________________________
- See previous concurrencesOFFICERII:DRPRII:ORARII:DRSOENRRSIGNATURE/RA//RA//RA//RA//RA/NAMECCASTOCEVANSWROGERSJ Luehman
- R Pascarelli
- DATE04/03/0604/03/0604/03/0604/12/0604/06/06E-MAIL COPY? YESNO YESNO YESNO YESNO YESNO YESNO YESNO NOTICE OF VIOLATIONFlorida Power and Light Company, Inc.Docket No. 50-250, 50-251Turkey Point Nuclear PlantLicense No. DPR-31, DPR-41 Units 3 and 4EA-06-027During an NRC inspection completed on December 31, 2005, a violation of NRC requirementswas identified. In accordance with the NRC Enforcement Policy, the violation is listed below:Technical Specification 3.7.1.2 requires two independent auxiliary feedwater trainsincluding three pumps during plant operation. Action statement 3 states, in part, that witha single auxiliary feedwater pump inoperable, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, verify operability of twoindependent auxiliary feedwater trains and restore the inoperable pump to operable statuswithin 30 days or place the affected units in at least Hot Standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, states, in part, thatmeasures shall be established to assure that conditions adverse to quality such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances are promptly identified and corrected.Contrary to the above, the licensee failed to restore the B auxiliary feedwater pump tooperable status within 30 days and did not place the unit in at least Hot Standby during this time. In this case, the B auxiliary feedwater pump was placed in service onSeptember 10, 2003, in an inoperable condition due to a misaligned radial bearing, and the inoperable condition was not identified until November 7, 2005. In addition, thelicensee failed to identify and correct the condition adverse to quality during this time frame even though pump bearing vibration levels and oil samples provided indication of the adverse condition.This violation is associated with a White significance determination process finding forUnits 3 and 4 in the mitigating systems cornerstone.The NRC has concluded that information regarding the reason for the violation, the correctiveactions taken and planned to correct the violation and prevent recurrence, and the date whenfull compliance was achieved is already adequately addressed on the docket in the information provided by Florida Power and Light Company's written response of March 13, 2006, and in NRC Inspection Report No. 05000250,251/2005005. However, you are required to submit awritten statement or explanation pursuant to 10 CFR 2.201 if the description therein does notaccurately reflect your corrective actions or your position. In that case, or if you choose to respond, clearly mark your response as a "Reply to a Notice of Violation - EA-06-027," and send it to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555, with a copy to the Regional Administrator, Region II, within 30 days of the date of the letter transmitting this Notice of Violation (Notice).If you contest this enforcement action, you should also provide a copy of your response, withthe basis for your denial, to the Director, Office of Enforcement, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.If you choose to respond, your response will be made available electronically for publicinspection in the NRC Public Document Room or from the NRC's document system (ADAMS),
Notice of Violation2to the extent possible, it should not include any personal privacy, proprietary, or safeguardsinformation so that it can be made available to the public without redaction. ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html. If personalprivacy or proprietary information is necessary to provide an acceptable response, then please provide a bracketed copy of your response that identifies the information that should beprotected and a redacted copy of your response that deletes such information. If you requestwithholding of such material, you must specifically identify the portions of your response thatyou seek to have withheld and provide in detail the bases for your claim of withholding (e.g., explain why the disclosure of information will create an unwarranted invasion of pers onalprivacy or provide the information required by 10 CFR 2.390(b) to support a request for withholding confidential commercial or financial information). If safeguards information is necessary to provide an acceptable response, please provide the level of protection described in 10 CFR 73.21.In accordance with 10 CFR 19.11, you may be required to post this Notice within 2 workingdays.Dated this 17 th day of April 2006 NRC EVALUATION OF RISK SIGNIFICANT FACTORSIn lieu of a regulatory conference, Florida Power and Light Company (FPL) provided a writtenresponse (dated March 13, 2006) to support its determination of the risk significance of a finding involving an inoperable auxiliary feedwater (AFW) pump. Based on a review of thisinformation, the following is provided as the basis for the NRC's final risk significancedetermination:1.Licensee Input - There was a time dependent degradation of AFW pump B. Therefore, upuntil October 30, 2005, it can be assumed that the pump would have performed itsintended function for at least 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. This was based upon the completion of a 2.1-hour surveillance run on October 10, 2005.NRC Disposition - The historical information provided about AFW pump B supported thecontinuation of selecting the fail-to-run basic event surrogate for the performancedeficiency. However, the information provided did not support that the surveillance test ofOctober 10, 2005, indicated that the pump would operate for at least 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> up untilOctober 30, 2005. From the completion the 2003 bearing mis-installation the pump's vibration was twice what it had been before bearing replacement and progressively worsened to five times its original value over the ensuing time period. Periodic oil samples taken since 2003 were also problematic, and on occasion, the bearing indicated high temperature. Upon disassembly there was grease caking, uneven tooth wear at thecoupling, and flaking of the sleeve bearing babbit. The as-found condition clearly indicated the potential for imminent failure. How much earlier in the exposure period the pump would have failed cannot be exactly selected. Therefore, consistent with NRC Manual Chapter 0609, a t/2 correlation was used. All of these factors collectively indicated that pump failure could have happened anytime during the mission time.
Recognizing that surveillance performance does not represent actual demand conditions(longer duration, higher pressure, and flow increasing shaft loading), no correlation for bearing performance between test operation and that which would be applicable for an actual demand was provided. Given the bearing's condition/possible pump failure mechanism, insufficient information was provided to support that bearing failure was a function of cumulative pump operation. However, for analysis purposes, the post-reactor trip performance of AFW pump B on March 22, 2005, was evaluated as the break point between failure in less than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or at greater than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. This is because the information provided indicated that the pump operated in a post-trip condition for greater than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. To simplify the analysis, only this exposure period of 63% of a year was quantified. Therefore, the input was partially included in the NRC's final significancedetermination.2.Licensee Input - For the exposure time prior to October 30, 2005, with AFW pump Boperating for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> prior to failure, the decay heat within the reactor would be lower, allowing a longer time for operators to perform any actions. This would change the performance shaping factors for any human reliability failure pr obabilities from what wasoriginally developed in the probabilistic risk assessments (PRA).NRC Disposition - It is true that the decay heat would be less with a subsequentlengthening of the time to core damage given a longer operation of AFW pump B.
However, this does not automatically cause a shift in the human error probability(particularly an order of magnitude shift). Each basic event involving operator error must NRC Evaluation of Risk2 Significant Factorsbe evaluated since the performance shaping factor for time may already be a minor inputor part of a dependency calculation that is insensitive to time. In addition, the attempted human action may have been a function of a particular setpoint or set of conditions which is not directly affected by the decay heat load. Finally, the quantified analysis was only for the time frame of less than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. Therefore, an alteration of the human error probabilities did not need to be considered in the quantification analysis.3.Licensee Input - Due to the time dependent nature of AWF pump B's failure, additionaloffsite power recovery actions should be added to the PRA.NRC Disposition - There was no basis provided by the licensee to support this statement. Consequently, the specific actions could neither be identified nor considered in any quantification of the safety significance. In addition, the dominant accident sequenceswere not initiated by a loss of offsite power. Therefore, this input was not included in the final significance determination.4.Licensee Input - Using a 24-hour mission time for the three AFW pumps and two standbysteam generator pumps overestimates the probability of failure.NRC Disposition - This statement is true for all sequences that exclusively include "failureto run" basic events for any pumps including the pumps mentioned above. However, this is the standard methodology used in PRAs. To perform such an involved calculation would be very time consuming and of marginal value. The licensee did not provide any quantification as to the real effects of using this methodology on the PRA results.
Therefore, this input was not included in the final significance determination.
5.Licensee Input - For that exposure time prior to November 30, 2005, with the lower decayheat level, the success criteria for feed and bleed can be modified from 2 of 3 reactor coolant system power operated relief valves to 1 of 3. The results of thermal-hydrauliccomputer simulations were provided to support this statement.NRC Disposition - Given the way in which the final significance determination wasaccomplished, the risk contribution in which the AFW pump B was postulated to operatefor greater than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> was not critical. Consequently, an extensive evaluation into possibly changing the success criteria was not conducted. The NRC recognizes thatmaking changes in PRAs like this on time dependent failures is not atypical. However, the substantial information necessary to support such a change in success criteria was not provided. Therefore, this input was not included in the final significance determination.6.Licensee Input - The Turkey Point probabilistic safety analysis (PSA) used generic datafor basic events. When the new "generic" data from the draft mitigating systemsperformance indicator (MSPI) program was inserted into the PSA, comparable results with the simplified plant analysis risk (SPAR) were achieved.NRC Disposition - The input was included in the final significance determination.7.Licensee Input - Turkey Point has additional and diverse plant specific secondary sideheat removal features. Qualitatively, the risk impact of failing one AFW pump is minimal. Even with the failure of an AFW pump, Turkey Point still has the same degree of NRC Evaluation of Risk3 Significant Factorsdefense-in-depth and margin of safety as a majority of pressurized water reactors. Thenumber and diversity of secondary side heat removal systems provides a strong basis thatthe loss of one AFW pump is not risk significant.NRC Disposition - All evaluations performed under Phase 2 and Phase 3 of thesignificance determination process (SDP) have recognized and included these diverse means in the analysis. The Phase 2 SDP worksheets and the computer models used incorporated the strengths and weaknesses associated with all the features mentioned inFPL's letter of March 13, 2006. Due to the nature of the initiating event or dependency involved with the failure of a particular basic event, all of these features are not available to provide secondary side heat removal. Without an informed understanding of these conditions, one cannot draw an accurate qualitative conclusion regarding how the failure of one AFW pump affects the risk significance. Risk insights gained from reviewing any PRA associated with Turkey Point clearly indicate (depending upon the nature of the failure, exposure time, and possibility for recovery) that such a failure can be of at leastlow to moderate safety significance.8.Licensee Input - The fault exposure time does not reflect the time-dependent nature ofAFW pump B's condition. The draft MSPI program eliminates fault exposure time. Based upon conservative weighting factors, 12-quarter performance data, and the Institute for Nuclear Power Operations MSPI calculator; the MSPI for AFW is Green.NRC Disposition - As has been discussed in numerous public forums, a correlationbetween MSPI results and SDP results is not appropriate because the two programs monitor two different aspects of performance. In addition, the basis that MSPI is only appropriate to deal with the time-dependent nature of this performance deficiency is not justified. The SDP is adequately suited to deal with this situation as exemplified by using the fail-to-run basic event surrogate in the SDP analyses. Therefore, this input was not included in the final safety significance determination.9.Licensee Input - Using the Turkey Point PSA model was appropriate for Phase 2 SDP butwas overly conservative for a Phase 3 SDP.NRC Disposition - Phase 2 SDPs are defined as the results obtained from the SDPNotebooks. When an alteration or amplification of methodologies beyond the notebook is used, it is a defacto Phase 3 analysis. Using PRA models is the normal protocol for Phase 3 analysis. In this particular case, two PRA models (SPAR and licensee full scope) were used - both of which indicated the performance deficiency was of low to moderate safety significance.10.Licensee Input - Recovery of the AFW pump A is possible upon loss of the A directcurrent (DC) bus. The recovery activity is proceduralized and involves local operator actions to open valves and throttle flow. It has been quantified with a failure probability of 0.11.NRC Disposition - Although the actual methodology associated with acquiring this failureprobability was not provi ded, the NRC examined this possibility and did not include it in theanalysis. The procedure for responding to a loss of the A DC bus does not direct or provide a transition to the procedure that contained the instructions for operating AFW NRC Evaluation of Risk4 Significant Factorspump A locally. In addition, the procedure for responding to a loss of the A DC busspecifically stated that AFW pump A would be lost. Given a loss of the A DC bus and no specific cue, it is highly questionable whether operators would focus on these actions for recovering secondary side heat removal from a human reliability analysis perspective.11.Licensee Input - FPL offered that, when the AFW pump B failed within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, thedeadheading of the weak pump phenomena included in the PRA model would not occur.NRC Disposition - An NRC review of the procedures indicated that 20 minutes was a moreappropriate time for possible failure of the weak pump. For ease of analysis, only 66% of the scenario time was quantified in the final significance determination. Therefore, thisinput was partially included in the final safety significance determination.12.Licensee Input - The units were shutdown for select periods of time during the exposuretime.NRC Disposition - At the inception of the SDP, all parties recognized the excessive burdenassociated with re-creating the actual plant conditions during any exposure time.
Consequently, Phase 3 analyses use the averaged PRA model. This input was not included in the final safety significance determination.13.Licensee Input - When the new basic event probabilities and the time-dependent nature ofthe AFW pump B failure were inserted into the model, the risk result was less than 1E-6.NRC Disposition - For the final significance determination, Sensitivity Cases 1 and 2 ofyour letter of March 13, 2006, were evaluated. Cutset No. 3 was revised to exclude use of AFW pump A following a loss of DC bus A. The resulting change in core damage frequency was reduced by 63% to account for the postulated pump failure within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
The result was subsequently reduced by 66% to account for only that period of time when the weak pump could fail after 20 minutes. The quantification was 1.2E-6 (low to moderate safety significance). This quantification did not include the accident sequences that were not dependent upon the weak pump phenomena to fail AFW pump B for this 63% of the exposure time or any of the cutsets associated with the other 37% of the exposure time. Alteration of the original SPAR model by (.63)(.66) produced comparable results. Therefore, the NRC reached a different conclusion than that proposed by FPLregarding this performance deficiency.In conclusion, after considering the information developed during the inspection and theinformation FPL provided in its written response, the NRC has concluded that the finalinspection finding is appropriately characterized as White in the mitigating systems cornerstone. In summary, the NRC's risk assessment concluded that the factors identified in FPL's writtenresponse of March 13, 2006, were insufficient to warrant a significant change in our preliminary risk estimate.