ML20197B709
| ML20197B709 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 02/27/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20197B706 | List: |
| References | |
| NUDOCS 9803110368 | |
| Download: ML20197B709 (8) | |
Text
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j NUCLEAR REGULATORY COMMISSIOlJ WASHINGTON, D.C. masas m m1
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e SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 123 TO FACILITY OPERATING LICENSE NO. DPR 80 AND AMENDMENT NO. 121 TO FAClllTY OPERATING LICENSE NO. DPR-82 PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT. UNITS 1 AND 2 DOCKET NOS. 50 275 AND 50 323
1.0 INTRODUCTION
Cy application dated May 14, 1997, as supplemented by letter dated October 9, 1997. Pacific Gas and Electric Company (or the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License Nos.
DPR 80 and DPR 82) for the Diablo Canyon Nuclear Power Plant, Units 1 and 2.
l The proposed changes revise the combined Technical Specifications (TS) for the Diablo Canyon Power Plant (DCPP) Unit Nos. I and 2 to; Extend surveillance test intervals (STIs) of the TS surveillances for a.
(1) reactor coolant system total flow rate monitoring instrumentation.
(2) instrumentation for radiation monitoring (3) instrumentation and controls for remote shutdown, and (4) instrumentation for accident monitoring.
b.
Revise affected sections of the BASES to reflect STI extensions, and c.
Incorporate an editorial change in TS 4.3.3.1. Table 4.3.3.
The supplemental letter provided additional clarifying information and did not change the initial no significant hazards consideration published in the Federal Reaister on July 8, 1997 (62 FR 40855).
2.0 BACKGROUND
The licensee recently conducted a feasibility study for increasing the length of the fuel cycle from the current 18 months to 24 months for both units of DCPP.
The results of this study indicated that a 24-month fuel cycle is not only feasible but also is beneficial because of fewer refuelings, improved outage scheduling and reduced personnel dose.
Therefore, the licensee has decided to implement the extended 24 month fuel cycles at both units of the DCPP, extending the current refueling-interval from 18 months to 24 months.
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l Current DCPP TS require that surveillance tests for some functional units be performed at least once per refueling interval.
O refore. STis for these functional units have been identified by a notation "R" in an appropriate column of the current TS tables. With the extended fuel cycle. STis for these functional units will be 24 months.
Therefore, for the 24 month (new refueling interval) STI. a new notation "R24" will be used.
The licensee has decided to retain the current 18 month ST) for some functionai units.
In their submittal, the licensee indicated that they would retain the existing notation "R" to indicate the 18 month ST1.
This will allow clear differentiation between 24 month and 18-month STis.
3.0 CHANGES AND EVALUATION 3.1 3rocosed TS Chanaes and Evaluation for the following 37 TS surveillance requirements, revise the frequency from "R." at least once per 18 months, to "R24." at least once per REFUELING INTERVAL (nominal 24 months, maximum 30 months).
1.
TS 4.2.3.4. Power Distribution Limits. Reactor Coolant System (RCS)
Total Flow Rate Indication 2.
TS 4.2.3.5, Power Distribution Limits. RCS Total Flow Rate Measurement 3.
TS 4.3.2.1. Table 4.3 2. line 3.c.4). Engineered Safety Features Actuation System Instrumentation Surveillance Requirements. Containment Ventilaticn Isolation. Containment Ventilation Exhaust Radiation High (RM 44A and 44B) 4.
TS 4 3.3 1. Table 4.3 3, line 3.a.3). aadiation Monitoring Instrumentation for Plant Operations Surveillance Requirements. Gaseous Activity. Containment Ventilation Isolation (RM-44A or 44B) 5.
TS 4.3.3.1. Table 4.3 3, 11ne-3.b.1). Radiation Monitoring instrumentation for Plant Operations Surveillance Requirements.
Particulate Activity Containment Ventilation Isolation (RM 44A or 44B) 6.
TS 4.3.3.5.1 Table 4.3 6. line 2. Remote Shutdown Monitoring Instrumentation Surveillance Requirements. Pressurizer Pressure 7.
TS 4.3.3 5 1. Table 4 3 6, line 3. Remote Shutdown Monitoring Instrumentation Surveillance Requirements. Pressurizer Level 8.
TS 4.3.3.5.1. Table 4.3 6 line 4. Remote Shutdown Mon 1toring Instrumentation Surveillance Requirements. Steam Generator W1de Range Water Level 9.
TS 4.3.3.5.1. Table 4.3 6 line 5. Remote Shutdown Monitoring Instrumentation Surveillance Requirements. Steam Generator Pressure
3-10.
TS 4.3.3.5.1. Table 4.3 6. line 6. Remote Shutdown Monitoring Instrumentation Surveillance Requirements. Condensate Storage Tank Water Level 11.
TS 4.3.3.5.1. Table 4.3-6, line 7. Remote Shutdo!n Monitoring Instrumentation Surveillance Requirements. Auxiliary feedwater Flow I
12.
TS 4.3.3.5.1. Table 4,3 6, line 8. Remote Shutdown Monitoring Instrtimentation Surveillance Requirements. Charging Flow 13.
TS 4.3.3.51 Table 4.3 6 line 9. Remote Shutdown Monitoring Instrumentation Surveillance Requirements. 0S Loop 1 Temperature Indication 14 TS 4.3.3.5.2. Remote Shutdown Instrumentation and Controls. Control Circuit and Control Transfer Switches 15.
TS 4.3.3.6. Table 4.3 7. line 1. Accident Monitoring Instrumentation.
Containment Pressure 16.
TS 4.3.3.6. Table 4.3-7. line 2. Accident-Monitoring Instrumentation.
Reactor Coolant Outlet Temperature -Tm (Wide Range) 17.
TS 4.3.3.6. Table 4.3 7, lite 3. Accident Monitoring Instrumentation.
Reactor Coolant inlet Temperature T% (Wide Range) 18.
TS 4.3.3.6. Table 4.3 7. line 4. Accident Monitoring Instrumentation.
Reactor Coolant Pressure - Wide Range 19.
TS 4.3.3.6. Table 4.3 7. line 5. Accident Monitoring Instrumentation.
Pressurizer Water Level 20.
TS 4.3.3.6. Table 4.3-7. line 6. Accident Monitoring Instrumentation.
Steam Line Pressure 21.
TS 4.3.3.6. Table 4.3 7, line 7. Accident Monitoring Instrumentation.
Steain Generator Water Level - Narrow Range 22, TS 4.3.3.6. Table A.3-7. line D. Accident Monitoring Instrumentation.
t Refueling Water Storage Tank Water Level 23.
TS 4.3.3.6. Table 4.3 7. line 9. Accident Monitoring Instrumentation.
Containment Reactor Cavity Sump Level Wide Range 24.
TS 4.3.3.6. Table 4.3-7, line 10. Accident Monitoring Instrumentation.
Containment Recirculation Sump Level - Narrow Range 25.
TS 4.3.3.6. Table 4.3 7. line 11. Accident Monitoring Instrumentation.
--- Auxiliary Feedwater Flow Rate
4
.., L 26.'
TS 4.3.3.6. Table 4.3-7 line 12. Accident Monitoring Instrumentation.
Reactor Coolant System Subcooling Margin Moniter 27.
TS 4.3.3.6. Table 4.3-7. line 13. Accident Monitoring Instrumentation.
PORV Position Indico:or 28.
TS 4.3.3.6. Table 4.3 7. line-14. Accident Monitoring Instrumentation.
PPRV Block Valve Position Indicator 29.
TS 4.3.3.6. Table 4.3-7. line 15. Accident Monitoring Instrumentation.
Safety Valve Position Indicator 30.
- TS-4.3.3.6. Table 4.3-7. line 16, Accident Monitoring Instrumentation.
In Core Therr.ocouples 31 TS 4.3.3.6. Table 4.3-7. line 17. Accident Monitoring Instrumentation.
Main Stean Line Radiation Monitor (RM 71. 72. 73, 74) 32.
TS 4.3.3.6. Table 4.3-7. line 18.- Accident Monitoring Instrumentation.
Containment Area Radiation Monitor - High Range (RM 30, 31-)
33.
TS 4.3,3.6. Table 4.3-7. line 20. Accident Monitoring Instrumentation.
Reactor Vessel Level Indication System 34 TS 4.4.4.1 b., Reactor Coolant System. Relief Valves. PORV Actu5 tion Instrumentation 35.
TS 4.4.9.o.lb., Reactor Coolant System. Overpressure Protaction Syste,;
Class 1 PORV Actuation Channel 36.
TS 4.4.6.1 b.
Reactor Coolant System. Leakage Detection Systems.
Containment Structure Sumps and Reactor Cavity Sump Level and F?ow Monitoring System:
37.
TS 4.4.6.1 c., Reactor Coolant System. Leakage Detection Systems.
Containment Fan Cooler Collection Monitoring System in their submittal, the licensee stated that the proposed surveillance interval modifications are based on guidance provided in GL 91-04. " Changes in Technica', Specification Surveillance Intervals to Accommodate a 24-Month Fuel Cycle." dated April 2. 1991, which provides guidance on how licensees should evaluate the effects of a 24-month surveillance interval in order to confirm that such an extension has an insignificant impact on plant safety.
Using plant-specific procedures based on Regulatory Guide (RG) 1.105. Revision 2.
" Instrument Setpoints for Safety-Related Systems" and WCAP-14646. Revision 1.
" Instrument Calibration and Drift Evaluation Process for Diablo Canyon Units 1 and 2. 24-month Fuel Cycle Evaluation." the licensee has performed analyses of all affected instrument loops in order to verify that STIs of up to 30 months (24 months + 25% allowable tolerance) have an insignif. cant effect on plant safety and, would not invalidate any assumptions in the plant licensing basis.
In the case of radiation detection instruments, in addition to the GL 91-04 J
(.
guidance, the licensee included the guidance in RG 1.109. Revision 1.
" Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluation Compliance with 10 CFR 50. Appendix 1." and RG 1.111. Revision 1. " Methods for Estimating Atmospheric Trans) ort and Dispersion of Gaseous Effluents in Routine Releases from Lig1t-Water Cooled Reactors." in the instrument performance evaluation.
In GL 91 04, the staff identified seven issues pertaining to increasing the interval of instrument surveillance and identified specific actions that licensees thould take to address these issues.
The staff evaluated the licensee's submittal to verify that the licensee has addressed all seven
=-
issues and provided an accentable basis for increasing the calibration interval for instruments that are used to perform safety functions.
Based on
=j the staff's review, the staff concludes that the licensee has satisfactorily addressed these seven issues and confirmed that safety limits and safety analysis assumptions will not be exceeded when worst case instrument setpoint 3
drift has been taken into account ds discussed below.
In their submittal the licensee stated that drift values to support the 24-L month 3TI extension were determined using a statistically based method for all b
instruments involved except where there was insufficient drift data.
In the cases where there was insufficient instrument calibration data to establish a statistically significant sample for drift such as for some radiation detectors, a 30 month drift was determined through engineering judgment considering the manufacturer's specifications, drift exhibited by similar devices from the same manufacturer and employed in similar applications, and Westinghouse experience with similar devices.
For some cases, the proposed STI extensions were based on past calibration results. operating, surveillance and maintenance histories and a review of industry operating experience.
Drift determination by 1.:eans of data analysis or by use of engineering judgment / historical data is consistent with GL 91-04 guidance and has previously been reviewed and approved by the staff fo-TS modifications at DCPP and othei plants.
The licensee stated that all drift values and assumptions used for the evaluation of STI extensions at DCPP will be validated through the monitoring of future instrument performance.
The statistical drift evaluation method was based on guidance contained in WCAP-11082. Revision 5. " Westinghouse Setpoint Methodology for Protection Systems. Diablo Canyon Units 1 and 2, 24-Month Fuel Cycle Evaluation."
WCAP-11594 Revision 2. " Westinghouse Improved Thermal Design Procedure Instrument Uncertamty Methodology. Diablo Canyon Units 1 and 2, 24-Month fuel Cycle Evaluation." and WCAP-14646. Revision 1. " Instrumentation Calibration
-L and Drift Evaluation Process for Diablo Canyon Units 1 and 2, 24-Month Fuel Cycle Evaluation."
In this evaluation, drift data was examined for mechanistic outllers (instrument failures or data transcription errors) and statistically significant outlie'.3. The correlation of drift magnitude with time was used to check for drift time dependency and, from the final drift data, a statistical tolerance interval for drift was calculated.
The statistically determined drift was combined by the square-root-sum-of-squares method with other appropriate applicable error components to calculate 3 total instrument loon "- 4rtainty.
This is consistent with RG 1.105 criteria.
n
2 6-In the drift analysis, the licensee implemented a two ticr approach to drift uncertainty with varying degrees of probability and confidence levels. The first tier uses a 95 percent probability and 95 3ercent confidence level (hereafter referred to as a 95/95 criterion).
T1e 95/95 criterion is applied to instruments of the automatic protection systems including the reactor protection system and ESFAS.
The second tier uses a 95 percent probability and 75 The 95/perc ent confidence level (hereafter referred to as a 95/75 criterion).
75 criterion is applied to indication instruments of the remote shutdown and post-accident monitoring systems.
The staff noted that the application of the 95/95 criterion and the 95/75 criterion is consistent with tie guidance of RG 1.105 with regard to the importance to safety of the applicable instrunents and, is therefore, acceptable.
The licensee's evaluation of historical surveillance and maintenance data for instruments indicated that there have been few problems with the evaluated equipment. The licensee stated that, with the exception of the containment i
fan cooling unit (CFCU) for the leak detection function there were no indications that potential instrumentation performance problems would be cycle length dependent, or that potential degradation would be significant over the 30-month period of interest.
Therefore. increasing the surveillance interval will have a negligible impact on safety.
In the case of the CFCU.
i the accumulation of enrrosion products and debris in the CFCU drain lines is i
rycle-length dependent.
However, the licensee determined that such an accumulation will have an insignificant effect on the CFCU's leak detection function as RCS leakage levels of significance will be detected.
Thus, the licensee's evaluation indicated that there is no adverse iPpact from the proposed 24-month STI since the proposed changes will have no effect en safety limits, protection system setpoints, or limiting conditions for operation.
In addition to the above, the licensee stated that the proposed TS surveillance interval increase does not alter the intent or method by which the instrumentation inspections, tests, or verifications are conducted, does not alter the way any structure, system, or component functions and does not change the manner in which the plar.t is operated. The surveillance, maintenance, and operating histories indicate that the equipment will continue to perform satisfactorily during the longer surveillance interval.
The staff finds that the licensee's drift evalu6 tion as discussed above is consistent with the guidance of GL 91-04 and RG 1.105 and, is therefore, acceptable.
With regard to a NRC Bulletin 90-01. " Loss of Fill-0il in Transmitters Manufactured by Rosemount." the licensee stated that none of their previous commitments relating to monitoring and reviewing calibration data for some models of Rosemount transmitters in order to detect loss of fill oil will change and thus a high level of confidence in detection of potential loss of fill oil will be maintained. This is acceptable to the staff.
Based on the above review, the staff concludes that the proposed TS modifications to increase the STI for selected instruments to a 24-month interval are consistent with the guidance of GL 91-04 for extension of STIs and the guidance of RG 1.105 for evaluation of instrument setpoint uncertainties, and are therefore, acceptable.
3.2 -ProDosed Bases-Chanaes and Evaluation 3.2.1 tow Temoerature Overoressure Protection Add the following to the TS Bases for Iten'35. Page B 3/4 4-16. TS
- 4.4.9.3.lb., " Low' Temperature Cverpressure Protection."
"The instrument uncertainties are not included in the Technical Specification setpoints.
Uncertainties associated with LTOP instrumentation were determined in accordance with the guidance provided in WCAP 14040-NP-A. An allowance for the pressure uncertainty is provided by administrative controls as discussed above."
In their submittal, the licensee stated that. in accordance with prior a3 proved Westinghouse methodoiogy, the DCPP TS was not required to account for tie random instrument-uncertainties for the LTOP setpoints for the current 18 month fuel cycles. However, using the guidance of GL 91-04.- the licensee has determined that it would be appropriate and conservative to account for these un:ertainties. The licensee has used the same Westinghouse methodoleqy to develop the RCS heatup and cooldown crves, as well as the LTOP system setpoints. The licensee's evaluations indicated that the LTOP setpoint uncertainties including the actuation pressure and enabling temperature setpoints, were relativalv small and do not vary significantly with lie surveillance interval.
Thelicenseestatedthatthesesmallinstrument uncertainties will be accounted for by revising the existing administrative-controls analyses. instead of including them in the LTOP TS set Therefore, the proposed wording is being added to the TS Bases. points.
Administrative limitations on~RCP operation. charging pump. operability and injection flow path operability will-be revised as required to support the existing LTOP setpoints. The staff finds that the administrative controls to support the LTOP function will account for.the instrument uncertainties and the proposed changes to the Bases--section are consistent with the staff's approval of WCAP-14040. The staff, therefore. finds them acceptable.
3.2.2 Remote Shutdown instrumentation Revise the following TS Bases Sections as marked m pages B 3/4 3-3c.
-B 3/4 3 3d and B 3/4 4-16.of Attachment B of the licensee's submittal.
1.
TS Bases for Items 6 through 13. TS 4.3.3.5.1. " Remote Shutdown Instrumentation" 2.
T3 Bases for Item 14. TS 4.3.3.5.2. " Remote Shutdown Instrumentation" The proposed changes on the above pages of the BASES section are consistent with the proposed STI extension for the TS functions listed above. Therefore.
the changes are acceptable to the staff, o
3.2.3 Radiation Monitorino Instrumentation TS 4.3.3.1. Table 4.3-3. line 3.a.3). Radiation Monitoring Instrumentation for Plant Operations Surveillance Requirements, for Functional Unit 3.a.3).
Gaseous Activity. Containment Ventilatica Isolation (RM 44A or 44B): remove a duplicate line of information from the TS as marked on page 3/4 3-39 of Attachment B of the licensee's submittal.
The proposed change removes duplicate information and is, therefere.
administrative and editorial in nature. This change does not affect the design, operation, or testing of the plant but merely adds clarification by I
removing duplication. Therefore, the proposed change is acceptable to the staff.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the California State official was notified of the proposed issuance of the amendments. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments change surveillance requirements.
The NRC staff has determined that the amendments involve no significant increase 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 Comission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public coment on such finding (62 FR 40855). Accordingly, the amendments meet the eligibility criteria 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 amendments.
6.0 CONCLUSION
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 amendments will r.0t be inimical to the common defense and security or to the health iafety of the public.
Principal Contributors:
S.V. Athavale S. Bloom T. Dunning Date:
February 27, 1998 1