ML20005F581
| ML20005F581 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/08/1990 |
| From: | Ray H SOUTHERN CALIFORNIA EDISON CO. |
| To: | |
| Shared Package | |
| ML13303B180 | List: |
| References | |
| NUDOCS 9001160426 | |
| Download: ML20005F581 (16) | |
Text
i UNITED STATES OF AMERICA l NUCLEAR REOULATORY COMMISSION i i
Application of SOUTHERN CALIFORNIA l EDISON COMPANY, H AL, for a Class 103 Docket No. 50-361 J License to Acquire, Possess, and Use i a Utilization Facility as Part of. ) Amendment Application ,
Unit No. 2 of the San Onofre Nuclear ) No. 70 l Generating Station )'
SOUTHERN CALIFORNIA EDISON COMPANY, H AL. pursuant to 10 CFR 50.90, hereby submit Amendment Application No. 70 to Facility Operating License NPF-10.
This amendment application consists of Proposed License Change No. NPF-10-276 to Facility Operating License No. NPF-10. Proposed License Change NPF-10-276 is a request to revise Technical Specifications 3/4.3.3.5, " Remote Shutdown Instrumentation," surveillance requirements. This revision would revise the frequency of channel calibration surveillances from an 18 month interval to an interval at least once per refueling, nominally 24 months or maximum 30 inonths."
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9001160426 900108 PDR ADOCK 05000361
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Subscribed on this P/h day of 1TRM u M ov ,1990. :
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Respectfully submitted, ;
SOUTHERN CALIFORNIA EDISON COMPANY 1
By: . -
Hatold B. Ray Vice President .
V Subscribed and sworn to before me this 8/h day of 7 0 n ( ( A o o / 7 9(3 * *
- g MICHELE R. KAHAL ennuwm cooman 01: Commassa be, Dec. 38,IMO 4 (l1( l/ A.b'flllftf Notary Public in and for the :
State of California is 1
l Charles R. Kocher James A. Beoletto Attorneys for Southern California Edison Company By: k -
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i UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Application of SOUTHERN CALIFORNIA
, EDISON COMPANY, [I AL for a Class 103 Docket No. 50 362 License to Acquire, Possess, and Use t_
a Utilization Facility as Part of Amendment Application Unit No. 3 of the San Onofre Nuclear No. 56 Generating Station SOUTHERN CALIFORNIA EDISON COMPANY, [I a[. pursuant to 10 CFR 50.90, hereby submit Amendment Application No. 56 to facility Operating License NPF-15.
This amendment application consists of Proposed License Change No. NPF-15-276 to Facility Operating License No. NPF-15. Proposed License Change NPF-15-276 is a request to revise Technical Specifications 3/4.3.3.5, " Remote Shutdcwn Instrumentation," surveillance requirements. This revision would revise the frequency of channel calibration surveillances from an 18 month interval to an interval at least once per refueling, nominally 24 months or maximum 30 months."
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Subscribed on this P+h day of 'lfan I< d ? o ,1990, d3 Respectfully submitted, SOUTHERN CALIFORNIA EDISON COMPANY L
By: -
t H(rold B. Ray 1 Vice President Subscribed and sworn to before me this
?fh day of 30 nlut% 19'/D .
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'7) (4/( tit /f d (t /t a [
Notary Public in and for the State of California Charles R. Kocher James A. Beoletto Attorneys for Southern California Edison Company By:
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'ESCRIPTION AND SAFETY' ANALYSIS J PROPOSED CHANGE NPF-10/15 276 f.
This is a request to revise Technical Specification 3/4.3.3.5, " Remote Shutdown Instrumentation." .
Existino Soecifications:
Unit 2: ~See. Attachment "A" Unit 3: See Attachment "B" Pronosed Snecifications:
Unit 2: See Attachment "C" Unit 3: See Attachment "D" Suonortina Documentation:
Attachment "E" - Figures Attachment "F" - Surveillance History Review Attachment "G" - Instrumant Drift Study l Attachment "H" - Functional Analysis i Attachment."I" - Redundant Int.trument Monitoring System (RIMS) Description QtiGr.i.0110D s The proposed' change would revise Technical Specification 3/4.3.3.5, " Remote Shutdown Instrumentation," to increase the interval for surveillance tests, which are currently performed every 18 months, to each refueling, nominally 24 months and maximum 30 months.
Technical Specification 3/4.3.3.5, " Remote Shutdown Instrumentation," provides instrumentation operability and surveillance requirements for Remote Shutdown Monitoring System (RSM).to assure that sufficient capability is available to permit safe shutdown of the facility, or maintain hot standby from locations outside of the control room. This capability is consistent with General Design Criteria 19 of 10 CFR 50.
The systems required for safe shutdown can achieve either hot shutdown or cold shutdown. Information is provided at the remote shutdown panel to allow operators to monitor the status of the systems required to achieve either hot shutdown or cold shutdown.
Technical Specification surveillance requirement 4.3.3.5 and Table 4.3 6 specify the modes-and required frequency for the performance of the Channel Check and Channel Calibration for each RSM channel. Channel Checks are performed at monthly intervals, while Channel Calibrations are performed at an i
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. 18 month.intervs1..These surveillance requirements assure that the
- instrumentation is operable.
- 1.0 Introduction The Technical Specifications include requirements to calibrate transmitters located in areas which are not readily accessible during power operation. San Onofre Units 2 and 3 have both entered a nominal 24 month fuel cycle.
Therefore, absent approval of this change, a plant shutdown will be required
- to perform portions of these surveillances. To avoid the need for an otherwise~ unnecessary large man-rem exposure or unit shutdown, an evaluation
-was initiated to determine if surveillances could be modified for consistency
- with the 24 month fuel cycle.
The evaluation showed that the extension of the refueling interval to 24 months could be safely accomplished. This conclusion was arrived based on the following:
o Comparative Review of Surveillance Testing Monthly Channel Checks provide a reasonable level of assurance of-instrument operability, o Surveillance and Corrective Maintenance History Review Most instrumentation failures are imediately self revealing.
o Drift Analysis A plant specific instrument drift study provides. a statistical analysis of drift characteristics over an extended interval (taken as 30 months).
o Functional Analy!'s The functional analysis performs an assessment of Remote Shutdown instrumentation, performs a review to identify required function per. the applicable Station Procedure (Abnormal Operating Instruction) and makes an assessment of the impact of drift on the required function.
Table 4.3-6 lists the following instruments for Remote Shutdown Monitoring instrumentation:
- 1. Log Power Level
- 2. Reactor Coolant Cold Leg Temperature
- 3. 'r .rurizer Pressure
- 4. Pressurizer Level
- 5. Steam Generator Level
- 6. Steam Generator Pressure
- 7. Source Range Neutron Flux
- 8. Condenser Vacuum
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- 9. Volume Control Tank Level
- 10. Letdown Heat Exchanger Pressure
- 11. Letdown Heat Exchanger Temperature
-12. Boric Acid Makeup Tank level .
- 13. - . Condensate Storage Tank level
- 14. Reactor Coolant Hot Leg Temperature 4
15.- Pressurizer Pressure - Low Range
- 16. Pressurizer Pressure - High Range
- 17. Pressurizer Level
- 18. Steam Generator Pressure
- 19. Steam Generator Level
.The table designates a frequency for a Channel Check and a Channel
- Calibration. -The Technical Specifications define the Channel Calibration interval frequency,'"R", as-"at least once per 18 months." Channel Calibrations are required for each remote shutdown instrumentation channel at
- least once every 18 months. The proposed change would revise the requirement for this testing from the current 18 month . interval to a refueling interval,- >
nominally established as 24 months, or maximum 30 months. The 30 month interval is the maximum 25% extension of the surveillance interval permitted by Technical Specification 4.0.2.
s L 2.0 Methodoloav h
I Attachment "E", Figure 1 provides a flowchart of the method used to evaluate extending the calibration interval of each of the functional units. -As shown'on the chart, the surveillance testing and the l
surveillance and maintenance history were reviewed. In the cases where f drift'did not impact the instrument, the testing and historical review l were adequate to justify the surveillance extension. If transmitter l- drif t was a factor in the applicable Abnormal Operating Instruction L .(AOI) for the instrument, then the effect on operator decisions in
[ complying with the A01 was evaluated. This section provides an overview l ,
.of.the evaluation process.
2.1 Comoarative Analysis of Surveillance Testina
! A comparative analysis between on line and refueling interval surveillance tests was performed for RSM instruments. The on-line surveillance testing was reviewed for each of the functional units to L identify to what extent it encompasses testing performed at refueling l intervals. Attachment "E", Figures 2 through 4 provide a representation L
of these instrument loops and the testing boundaries. These on-line surveillances consist of Channel Checks. -The 18 month Channel Calibration verifies the operability of the entire loop. Table E-1 in Attachment "E" provides additional details regarding surveillance test
- requirements.
The on-line surveillance testing review was conducted to assure that all instrument channels under consideration are being monitored on a routine basis to detect inoperable conditions. The objective is to assure that l
all operability problems are being identified in a timely manner, and to l
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k determine operability.- the importance of the 18 month surveillances in maintaining l~
2.2- Surveillance and Maintenance History Review ,
A review of the refueling surveillance test results and corrective maintenance history was conducted on the components impacted by the extension of;the refueling surveillance interval.
The. approach taken was to evaluate the contribution of all of the Preventive-Maintenance (PM) program elements. The basis for PM interval 4
- extension is derived.from the Reliability Centered Maintenance (RCM) methodology. This methodology has been submitted by SCE to NRC letter dated September 5, 1989,-in support for the request for calibration
-extension for the Containment Area Monitors (NPF-10/15-266) and
. Containment High Range Monitors (NPF-10/15 267).
Several reviews are necessary in order to evaluate a surveillance for interval extension. A comparative analysis is performed of the PM surveillances to identify the different aspects of the surveillance tests. A secondary review determines if existing surveillances are detecting equipment problems and if operability is affected. Finally, a review of Corrective Maintenance (CM) history assures that all problems affecting operability were detected by a condition or time directed means.
indication Condition or time directed means include surveillance, alarm, or to the operator.
The surveillance becomes a candidate for interval extension if the CM review indicates failures affecting operability are detected and corrected without performing the surveillance.and if the surveillance history is free of failures affecting operability.
The PM surveillances performed on the RSM instrumentation include the 18 month calibration and monthly Channel Check. A review of the surveillances-indicates that the monthly Channel Check provides reasonable assurance of loop operability. Attachment "F" provides additional methodology details and the PM surveillance data.
The functional assessment was performed for all 19 instruments in the
. RSM Table 4.3-6.
2.3 Drift and Functional Analyses 2.3.1 Drift Analysis On line surveillances and the equipment history review provides a high level a over offuel assurance cycle. that the equipment does not degrade significantly However, minor changes in transmitter calibration may not be detected on-line.
To address this aspect of extending the surveillance interval, an analysis of the drift characteristics of pressure, differential pressure, and temperature transmitters was conducted.
-o 5-The results of this Instrument Drift Study have been provided, in part, in Southern' California Edison (SCE) to NRC letter dated May 15, 1989.
This letter was. submitted in support of PCN 290. PCN 290 requested a one-time exception be granted to the surveillance testing requirements of select instrumentation in use at San Onofre Nuclear Generating Station (SONGS)_ Unit 2.
In lieu of using generic vendor drift data, a plant specific review was performed of the long term drift characteristics of pressure, differential pressure-and temperature transmitters. For the Plant Protection System (PPS), this experienced long term drift was statistically adjusted to reflect the maximum drif t expected over a fuel cycle (taken as.30 months) at a 95% probability and 95% confidence level. For Accident Monitoring and Remote Shutdown Monitoring Systems, best estimate drifts, over a 30 month cycle, were generated. Attachment.
"G" provides additional details of the Instrument Drift Study.
2.3.2 Functional Analvsis -
For Accident Monitoring and Remote Shutdown Monitoring Systems (MS and RSM), a functional. analysis was performed to determine the impact of the revised drift allowances on the ability of the instrument to perform the intended A01' function. To impart additional conservatism to the analysis, the drift.allowables for most AMS and RSM instruments are based on 95/95 \alues, rather than best estimate values. The drift allowables determined from this effort are more conservative than generic vendor data. .The drift allowables were used to. calculate a loop accuracy, or, total uncertainty, value. The impact of the total uncertainty on the decisions that an operator is required to make in complying with the Abnormal Operating Instructions (A,01), was evaluated.
The details of the functional analysis are provided in Attachment "H".
3.0 Results ,
3.1 Comoarative Analysis of Surveillance Testina The review of surveillance testing confirmed that the performance of monthly Channel Checks provide-a reasonable level of assurance of instrument operability.
Figures 2 through 4, included in Attachment "E", provide Loop Functional Diagrams for all of the RSM instruments. These loop diagrams specifically identify the different aspects of the monthly Channel Check and 18 month calibration surveillances.
The Channel Checks are cross channel checks which compare various indications of the same process parameter. The Channel Checks provide a reasonable level of assurance that the loop is intact and that the transmitter has not failed. This cross-channel check is performed on a monthly basis.
The comparative analysis determined that the importance of the 18 month
6-calibration surveillance was to correct instrument drift, if it was occurring. A review of surveillance maintenance history discussed, in Section 3.2, summarizes.the results of any problems found during calibrations.- Section 3.3 discusses the'results of the drift study that was undertaken to determine the sensitivity of instrument drift to their
. calibration interval.
3.2 - Surveillance and Corrective Maintenance History Review A confirmatoryIsurveillance and CM history review verified that most instrumentation problems, identified to date, were being identified by the monthly Channel Checks.
A review and detailed PM surveillance history evaluation was provided for all RSM instruments, including those not exhibiting drift.
Compenents not exhibiting drift include the signal conditioning
+ electronics for all instruments, the Log Power Level instrumentation and Source Range Neutron Flux instrumentation. For these instruments, the surveillance and-corrective maintenance history review, coupled with the functional analysis, provide the basis for surveillance extension.
Based on the evaluation of the CM review, it is concluded that most of the instruments have not been experiencing substantial calibration problems. When calibration problems were identified, they were normally found during the cross Channel Checks. No repet'tive failures have occurred, and no instances were found involving redundant channels during the same time period. The data did not detect a correlation
'between the number of failures and the calibration interval.
The historical surveillance review included all surveillance records since the commencement of commercial operation to August 31, 1989.
Attachment "F" and "H" provide the details of the surveillance review and functional analysis.
3.3 Drift and Functional Analyses 3.3.1 Drift Analysis Results Instruments'for which drift was a factor were further evaluated. The Instrument Drift Sudy provides a conservative assessment of transmitter performance. A comparison of the results of analysis of the long term drift data is made to existing allowances for long term drift. The results are also compared to revised allowances for long term drift Ossuming 30 month intervals between calibrations. Use of the revised allowances for long term drift in evaluations of instrument performance with respect to the A01s provides a sound basis for extending the calibrations interval of these tranmsitters. Additional details are provided in Attachment "G".
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3.3.2 Functional Analysis.
The drift study results were evaluated and the applicable Abnormal Operating instruction (A01) was reviewed in order _ to identify-instrument parameters and function. This review established the allowable error for RSM instrumentation. The assessment of the revised drift compared-of the allowable error from the A01 to the instrument uncertainty including calculated drift error from the instrument drift study. The comparison verified the ability cf the instrument _to perform the intended function.
Attachment "H" provides additional details regarding the functional analysis.
3.4 Redundant Instrument Monitorina System (RIMS)
Data to support this extension request is also provided by the 12 month operating experience of the Redundant Instrument Monitoring-System (RIMS). The RIMS was developed by SCE to improve the capability for on-line monitoring of instrumentation. The RIMS performs detailed cross-Channel Checks of monitored instruments. It can be used to identify i anomalous instrument behavior. The RIMS evaluated transmittert similar L to those analyzed; by this proposed change. Trending of RIMS data over ,
l the past~ year has demonstrated'the conservative values for drift
- - calculated by SCE. This serves to provide an additional level of
! assurance of instrument operability. Attachment "I" provides a discussion of RIMS and typical plots of instrument performance.
p 4.0 Conclusions .
The proposed: change would increase the surveillance ir$terval from 18 months to " refueling interval" for a nominal 24 month cycle, and maximum l
30 month cycle, the actual time interval between surveillances will be a
, function of the plant . capacity factor for that. particular fuel cycle.
l The design equilibrium fuel cycle length will be between 500 and 550
- effective full power days (EFPD). Assuming a capacity factor between 70% and 80%, the actual cycle length, and the surveillance-interval, would be between 21 and 26 months. Currently, Specification 4.0.2 allows a 25% extension of surveillance intervals which would accommodate L uninterrupted operation for the equilibrium cycle length.
This evaluation consisted of a comprehensive review of all of the I critical RSM instrumentation. The evaluation consisted of a comparative
, analysis of all PM surveillances, a PM history review for all i instruments, a statistical evaluation of instruments impacted by drift and a functional analysis of instrument function in the applicable Abnormal Operating Instruction (A01). The study findings support the extension of the calibration interval.
An analysis of the allowable uncertainties of instrumentation used in the SONGS A01 was performed. The instrument uncertainties, considering the long term drift experienced at SONGS Units 2&3, were calculated.
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' Comparisons'of the calculated uncertainties to the allowable
. uncertainties demonstrate that the operator has sufficiently accurate information to effectively implement the applicable A01.
An'added level of assurance is provided by the classification of these components as Quality Class-II. For Quality Class II components, the applicable requirements of 10CFR50, Appendix-8, Quality Assurance Criteria for Nuclear Power Plants have been met to ensure the highest quality standards. This provides assurance that the instruments will ,
perform the intended function, g in general, redundant and diverse indication of important process d parameters are available. This provides a~ backup source of information to the operators to confirm the primary indication. ,
4 1 It is concluded that extending the surveillance interval of Remote ;
Shutdown Monitoring ~ Instrumentation to a maximum of 30 months is ~
acceptable.
The~ RIMS can be used to identify anomalous instrument behavior. The RIMS _' evaluated transmitters similar to those analyzed by this proposed '
change. Trending of. RIMS data over the past year has demonstrated-the conservative values for drift calculated by SCE. This serves to provide an additional level of assurance of instrument operability.
Safety Analysis ;
l '. Will' operation of the facility in accordance with-the proposed change
-involve ~a significant increase in the probability or consequences of any -
accident-previously evaluated?
' Response: No.
The proposed change only requests an increase in the interval between calibrations for instrumentation used for monitoring and controlling the -
unit in the unlikely event requiring control room evacuation. This increase in-the calibration interval will make it consistent with the existing design fuel cycle length.
SCE has performed a comprehensive evaluation of the effect of extending the -calibration interval for all Remote Shutdown Monitoring (RSM) System instrumentation. The functional analysis consisted of a an evaluation of instrument function, comparative analysis of all PM surveillances, a review of preventive maintenance surveillances and corrective maintenance history, a statistical evaluation of instruments impacted by drift, and a functional analysis of instrument functions required in the Abnormal Operating Instruction (A01).
The confirmatory surveillance and CM history review served to identify problems experienced by the RSM instrumentation. This review confirmed that problems affecting technical specification operability are
r 9-identified independent of the refueling calibration surveillances through monthl y Channel Checks.
The functional assessment was performed for all RSM instruments. For some instruments, transmitter drift had the potential for operator actions required by the A01s. For these instruments, an additional evaluation was performed. This functional analysis focused on the maximum drift.effect of the sensing device on the refueling calibration interval. For these San Onofre Nuclear Generating Station (SONGS) Units 2.and 3 transmitters, an instrument drift study was performed. The analysis 1s based on 125% of the nominal calibration interval, or 30 inonths maximum.
. The long term drift characteristics of pressure, differential pressure and temperature transmitters included in-the RSM System were determined.
This Instrument Drift Study provides an analysis of the calibration history of certain instruments used in the Remote Shutdown Monitoring
.(RSM) System. -The experienced long term drift was statistically
. adjusted to reflect the maximum drift expected over a fuel cycle, taken-as 30 months. For instrumentation related to RSM, the drift was determined on a best estimate basis.
Orift allowables were determined based on this study. To impart additional conservatism, 95/95 values, rather than best estimate values were used for most RSM instruments. The drift' allowances were determined by inspecting the 30 month drift values and selecting'a bounding value for each transmitter model. The allowable values:were then used,-in combination with other instrument uncertainties, to calculate:a loop accuracy or total uncertainty value. The impact of the total uncertainty on the decisions that an operator is required to make in complying with the A01 was evaluated in the Functional Analysis.
It was determined that the impact of the increased drift due to extending the surveillance interval of RSM instrumentation does not
-appreciably affect operator decisions in carrying out the applicable Abnormal Operating Instruction (A01). It was concluded that the applicable AOI.can be successfully implemented in post-accident situations considering the instrument uncertainties resulting from the
-drift study.
In the unlikely event requiring control room evacuation, the operator would use the RSM instrumentation in conjunction with other available indications, as required. A principal aspect of operator control of the unit is the trend of a parameter. The other factors include qualitative parameter use. In many instances, it is more important to understand the trend of a process parameter rather than know the precise value of the parameter.
Two channels of most parameters are included in the RSM system.
Substantial differences between these two indications would alert the operator to check other redundant or diverse indication at decision points.
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10-Comparisons of the RSM instrumentation to other instruments monitoring the same process are made on a monthly basis. This monthly surveillance-provides a reasonable level of assurance that the equipment is capable of performing its design function.
An added level of assurance is provided by the classification of these components as Quality Class II. For Quality Class Il components, the applicable requirements of 10CFR50, Appendix B, . Quality Assurance -
Criteria for Nuclear Power Plants have been met to ensure the highest quality- standards. This provides assurance'that the instruments will perform the intended function.
The study findings support the extension of the calibration interval.
Based on the impact of these factors, it is concluded that the proposed change does not involve a significant increase in the probability or consequences of any previously evaluated accident.
Additionally, the instrumentation associated with this technical specification is intended for remote shutdown and changes in the calibration frequency will have no effect on the probability of an accident. .The instrumentation is sufficiently stable, as demonstrated by an evaluation of the historical calibration data, to maintain the accuracy required to perform its remote shutdown function.
- 2. Will operation of the facility in accordance with this proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?
Response: No The proposed change does not modify the configuration of the facility or its mode of operation. The proposed change extends the calibration interval for the RSM instrumentation from 18 to 24 months, nominally, and from 22.1/2 to 30 months, maximum. Instrument parameters are maintained within the allowables defined in the Functional Analysis .
Therefore, the proposed change will not create the possibility of a new or different kind of accident from any previously evaluated.
- 3. 'Will operation of the facility in accordance with the proposed change involve a significant reduction in a margin of safety?
Response: No The proposed change increases the calibration interval to a maximum of 30 months for instruments which are used for the Remote Shutdown Monitoring System. The surveillance and corrective maintenance history review has confirmed that significant problems are identified as the result of monthly Channel Checks.
Drift allowables of RSM instrumentation were established. The allowable values were then used to generate total loop uncertainties for RSM instrumentation. An evaluation was performed to assess the impact of
f j j the total loop' uncertainties on effective A01 implementation.. This evaluation confirmed that the long term instrument drift values do not i appreciably affect the ability to use these instruments as intended in the A01.
'The proposed change will not involve a significant' reduction in the-accident and transient analysis margin of safety-for RMS instrumentation.
l SAFETY AND SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION Based on the above Safety Analysis, it is concluded that: (1) the proposed change does not constitute a significant hazards consideration as defined b'y:
10 CFR 50.92; and (2) there is reasonable assurance that the health and safety of the public.will not be endangered by the proposed change; and (3) this action will not result in a condition which significantly alters the impact of the station on the' environment as described in the NRC Final Environmental-Statement.
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NPF-10/15 276 t-c ATTACHMENT A SONGS UNITS 2'
. EXISTING TECHNICAL SPECIFICATICNS
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