ML20212J412
| ML20212J412 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 06/23/1999 |
| From: | Dugger C ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| EA-98-022, EA-98-22, W3F1-99-0100, W3F1-99-100, NUDOCS 9907010151 | |
| Download: ML20212J412 (14) | |
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e- p' h- .
Enttrgy Operations, Inc.
Kdlona. LA 70066-0751 Tel 504 759 6660 V ce e cien p ra ans Waterfor#
W3F1-99-0100 A4.05 PR June 23,1999 U.G. Nuclear Regulatory Commission ATfN: Document Control Desk Washington, D.C. 20555
Subject:
Waterford 3 SES Docket No. 50-382 License No. NPF-38 Response to Enforcement Action (EA)98-022 and URI 9906-04 This will respond to the Nuclear Regulatory Commist on (NRC) Staffs letter dated May 24,1999, regarding the staffs reconsideration of enforcement action (EA)98-022. in that letter you requested we provide a written response detailing the actions we have taken or plan to take to address the Staffs concerns with our ability to demonstrate adequate flow availability to meet design requirements for the following: >
e High Pressure Safety injection Pumps A, B and AB e Auxiliary Component Cooling Water Pump B f . Emergency Feedwater Pumps A, B and AB l This issue is also discussed in Section E8.23 of Inspection Report 99-06, dated May l 18,1999. We understand this issue is being tracked as an unresolved item (URI 50-
- l. 382/9906-04). Attachment 1 to this letter provides the Entergy Operations, Inc. (EOl)
I evaluation of the performance adequacy of the above referenced equipment. In addition to the requested information, this letter provides a response to the modified ,
characterization of Violations C and D.0 4 0;10 Vi11ation C EOl has carefully reviewed the information provided in the modified characterization of Violation C. We maintain the position provided in our letter (W3F1-98-0119) dated July 29,1998. Our corrective actions for Combustion Engineering (CE) Info Bulletin 91-05, which identified a case where instrument uncertainty had not been adequately 7 9907010151 990623 PDR G
ADoCK 05000382' PDR i
L_
bf i l
e Response to Enforcernent Action (EA)98-022 and URI 9906-04 W3F1-99-0100 Page 2 June 23,1999 incorporated into Technical Specifications, were not prompt. However, despite the missed opportunities, we maintain that comprehensive corrective actions were in progress to identify and resolve instrument uncertainty issues at Waterford 3.
Violation D EOI agrees the issue discussed in Violation D involving differences in instrument uncertainty determined by Waterford calculation EC-195-011, "SI-HPSI Flow Instrumentation Calculation," and the original ABB/CE calculation (612752-MPS-SCALC-001) should have been evaluated in a more timely manner. However, the Staff's concerns with timeliness are captured in Violation C.
t We disagree with the Staff's position that "conservatisms integral to Appendix K methodology were not intended to and do not encompass flow measurement uncertainties." We believe the Staffs position regarding the need to explicitly account for flow measurement uncertainties in surveillance requirements supporting ,
Appendix K analyses is not consistent with the 10CFR50 Statements of Consideration. The Statements of Consideration pertaining to changes in Appendix K and 10CFR50.46 to allow the option of a realistic Loss of Coolant Accident methodology state:
" calculations performed using current methods andin accordance with the current requirements result in estimates of core cooling performance that are .significantly more conservative than estimates based on the improved knowledge gained from this research.
It is now confirmed that the methods specified in Appendix K combined with other analysis methods currently in use, are highly conservative and that the actual cladding temperatures which occur during a LOCA would be much lower than those calculated using Appendix K methods." '
In addition, the Commission concluded the following during the rulemaking hearings on Appendix K:
l "The Commission is confident, however, that the criteria and evaluation models set forth here are more than sufficiently I'
' Refer to page 50-SC 53 of the 10CFR50 Statements of Consideration, dated September 29,1995
_ _ _ _ _ _ _ _ _ i
L.
Response to Enforcement Action
-(EA)98-022 and URI 9906-04 W3F1-99-0100 Page 3 June 23,- 1999 conservative to compensate for remaining uncertainties in the models orin the data." "
This clearly reflects a belief that an Appendix K evaluation modelis sufficiently conservative to cover a number of small uncertainties, such as HPSI flow measurement uncertainties.
The Emergency Core Cooling System (ECCS) at Waterford 3 was approved by the NRC Staff under the provisions of 10CFR50 Appendix K. As such, the Staff's position regarding the need to explicitly account for the flow measurement uncertainties and valve position variability is not consistent with the plant's licensing basis. It appears from the available information on Appendix K that previous regulatory positions resulting in the licensing of Waterford 3 and other facilities
' accepted a generalized method of addressing instrument uncertainty." The Staff's position documented in the letter dated May 24,1999, does not provide a basis for reconsideration of the infonnation in the 10CFR50 Statements of Consideration nor does the Staff's position address our view of valve position variability being an inherent part of the system behavior. Specifically, changing the valve position under testing conditions would impact the measured parameters (i.e., flow and pressure),
We do not feel the Staff has provided sufficient information to support their position, and we maintain our position that a violation of 10CFR50 Appendix B Criterion XI,
" Test Control," has not occurred since the design and testing of the ECCS at Waterford 3 is in compliance with the applicable codes and standards.
URI 50-382/9906-04 4 EOl has carefully reviewed the information provided in your letters dated May 18, 1999, and May 24,1999. EOl would first like to clarify its position on this issue. It ,
appears that the NRC Staff may have misunderstood our position on tha issue by I viewing the following statement from an EOI engineering document out of its proper context:
il
"...the application of instrument uncertainty does not apply to the high pressure safety injection system and several other safety-related systems... because the application of instrument uncertainty for these systems is not considered to be significant to safety."'
" Refer to page 1094 of the "Rulemaking Hearing: Acceptance Criteria for Emergency Core Cooling Systems for Light-Water Nuclear Power Reactors (CLI-73-39)," December 28,1973
"' Refer to Issue # 13 in NUREG-0133 s
Response to Enforceme$t Action (EA)98-022 and URI 9906-04 W3F1-99-0100 Page 4 June 23,1999
~ EOl recognizes that consideration of instrument uncertainties is a significant industry issue, and has maintained an active role in the industry effort to obtain a graded approach for the consideration of instrument uncertainties. We committed in response to the Staff's 10CFR50.54(f) letter dated October 9,1996, to ensure that the basis for the Waterford 3 Technical Specification Limiting Conditions for Operation and Surveillance Requirements include appropriate consideration for instrumont uncertainty. A status of our instrument uncertainty effort was provided to the Staff in our letter (W3F1-99-0053) dated March 31,1999.
The above EOl statement, quoted in your letter dated May 24,1999, was based on a more in-depth response to an inspector's inquiry during the Architect & Engineering Follow-up Inspection conducted from April 5 to 9,1999, at Waterford 3. The response was documented in an engineering document (ER-W3-99-0428-00-00),
whic.h applied uncertainfies to inservice Test criteria beyond the requirements for instrument inaccuracies given in Section XI of the ASME code. Under our plant's Technical Specifications and 10CFR50.55a, the Inservice Testing Program for safety-related pumps at Waterford 3 must meet the requirements c :ME Section XI, Subsection lWP and ASME/ ANSI OM-1987 Addenda Part 6. We maintain cur i
position that the application of instrument uncertainty to ASME Section XI testing of safety-related pumps is not required by our licensing basis or the ASME code. The !
information provided in ER-W3-99-0428-00-00 was beyond the scope of ASME Section XI in an attempt to evaluate the inspector's concerns since the ability of a system or structure to perform its specified tunction may have been called into question. l With this in mind, Attachment 1 provides an engineering evaluation supporting the operability of the safety-related pumps questioned by the Staff. This evaluation supplements the previously provided information in ER-W3-99-0428-00-00, but does not provide new design basis information for the plant. The evaluation shows that
. each of the pumps discussed above is capable of meeting its safety function and i satisfying the surveillance and ASME Section XI test requirements. As explained in oix letter to the Staff dated March 31,1999, EOl maintains appropriate consideration of instrument uncertainty was applied to the Waterford 3 Technical Specification I Limiting Conditions for Operation and Surveillance Requirements. We believe the application of instrument uncertainties (e.g., process fluid density, system flow .
resistance, total instrument loop uncertainties, etc.) to both ASME Section XI tests i
J I
Response to Enforcement Action (EA)98-022 and URI 9906-04 '
W3F1-99-0100 Page 5 June 23,1999 and tests supporting 10CFR50 Appendix K ECCS Models is not consistent with the licensing basis of our facility. Section 4.0 of Attachment 1 summarizes EOl's position on the application of instrument uncertainties. If the Staff concludes further regulatory action is necessary on the issue, we request such issues be addressed from a generic industry perspective.
If you have any questions concerning this response, please contact E. Perkins, Licensing Manager, at (504) 739-6379.
Very truly yours,
/^ / ;
}F C.M. Dugger )
Vice-President of Operations )
Waterford 3 l l
CMD/BVR/rtk Attachment cc: E.W. Merschoff (NRC Region IV), C.P. Patel (NRC-NRR),
D.A. Powers (NRC-DRS), R.W. Borchardt (NRC, Office of Enforcement),
S.J. Collins (NRR), J. Smith, N.S. Reynolds, NRC Resident inspectors Office
Attachm:nt 1 to W3F1-99-0100 l Paga i of 9 ATTACHMENT 1 ENGINEERING EVALUATION TO ADDRESS URI 50-382/9906-04 )
l
1.0 INTRODUCTION
l Based on information provided by Entergy Operations, Inc. (EOl) in Reference 2, the NRC Staff stated in the letter dated May 24,1999, that three safety-related systems and multiple safety-related pumps (including the high pressure safety injection l system) may not have sufficient design margins to account for all instrument l uncertainties (including orifice plate tolerances, tap locations, and process temperatures, etc.). The evaluation in Reference 2 applied uncertainties to inservice i Test criteria beyond the instrument inaccuracies accounted for in EOl's inservice Testing Program. The NRC Staff also disagreed with an implied position that the application of instrument uncertainty is not required for the high pressure safety 1 injection system and several other safety-related systems because the application of instrument uncertainty for these systems is not considered to be significant to safety.
The NRC requested that Waterford 3 respond in writing within 30 days of the date of this letter regarding the actions taken or planned to address this issue.
Inservice testing is required per 10CFR50.55a(f) to verify the operational readiness -
of safety-related pumps in accordance with ASME Section XI, Subsection IWP.shd ASME/ ANSI OM-1987 Addenda Part 6. The objective of ASME Section X is "to afford reasonably certain protection of life and property and to provide a margin for deterioration in service so as to give a reasonably long, safe period of usefulness".
ASME Section XI requires safety-related pumps to be tested in accordance with ASME/ ANSI OM, Part 6, which provides specific accuracy requirements for instruments to assure the results of the test are repeatable. ASME Section XI testing at Waterford 3 is performed to the specific instrument accuracy requirements, but i does not include instrument uncertainties. Section 2 of this attachment describes the distinction between instrument uncertainty and instrument accuracy as applied at Waterford 3 for ASME Section XI testing of safety-related pumps.
The application of instrument uncertainty to ASME Section XI testing of safety-related pumps is not required." However, the evaluation described in ER-W3 0428-00-00, which applied instrument uncertainty to ASME Section XI test results, was provided in response to an NRC Staff question during the Architect and Engineering Follow-up." Section 3 of this attachment contains supplemental information to provide reasonable assurance that the safety-related pumps questioned by the NRC Staff are capable of performing their specified safety
- Reference 1, page 4," Response to Violations C & D" section, paragraph 2
' Forward to ASME Section XI
" ASME/ ANSI OM-1987 Addenda Part 6 Paragraph 4.6.1.1 and Table 1 (See also Section 4.7 and Attachment 8.2 of Reference 2 and paragraph 5.5.4 of Reference 5
'" Reference 1, Reference 2 (Section 2.0 and 4.7) and Reference 3
1
. Attachm:nt 1 to i W3F1-99-0100
. ,' ,' Page 2 of 9 functions. Section 4 details EOl's position regarding the application of instrument uncertainty.
]
l 2.0 INSTRUMENT ACCURACY vs. INSTRUMENT UNCERTAINTY Instrument accuracy is the algebraic difference between the indicated value and the true value of the physical quantity or condition being measured by the device. This is also referred to as the reference accuracy of the device. It includes the combined effects of hysteresis, conformity, dead band, and repeatability errors. Typically, the instrument accuracy used by a facility is the accuracy stated in the vendor's information for the device. As applied to ASME Section XI testing, the reference accuracies of the individual devices within an instrument channel (from the sensor to the indicator) are combined to determine the combined accuracy of the instrument.
Instrument uncertainty is the amount by which an instrument channel's output is in doubt (or the allowance made thereof) due to possible errors that have not been corrected. Instrument uncertainties are expressed with a random uncertainty and bias uncertainty term. Random uncertainties exist within a normal distribution about a true mean value. Bias uncertainties are a recurrent offset from the ideal value.
The random and bias uncertainties for an instrument channel are combined to develop the instrument uncertainty. Instrument unce:rtainty is typically defined using )
a 95/95 probability and confidence level. The random uncertainty terms are typically l combined statistically (Square-Root-Sum-of-the-Squares). The bias uncertainty terms are algebraically combined. Finally, the resultant random and bias uncertainty terms are algebraically combined to yield a total uncertainty. This is consistent with ISA S67.04 methodologies.
> Process measurement errors are those error terms in the actual process signal being detected by the process measurement device (sensor). These errors are associated with the deviations occurring between the process (water in a pipe) and the sensor input. Process measurement errors are a function of the characteristics of the rneasurement process and not a function of the performance of the instruments. For orifice flow measurement, variations and tolerances cause deviations from the assumed Reynolds number, orifice diameter, pipe diameter, orifice shape, physical location of the orifice, physical location and routing of the tubing from the orifice to the sensor, and density of the fluid at the orifice.
> Instrument errors are those errors associated with the performance limitations of the instrument channel components. These errors are associated with deviations occurring between the sensor input and the channel output device. This class of errors includes the accuracy of instrument channel devices and includes the device referenco accuracies, drift, environmental effects and the known factors that can affect the instrument response (resolution, dead band, reset, static pressure effects, overpressure effects, power supply effects, accident environment effects, etc.).
Attachm::nt 1 to W3F1-09-0100 Page 3 of 9
> "Other errors"is a term used to account for those errors that are neither process i nor instrumentation. This includes the errors associated with the calibration {
process, calibration tolerances, calibration test equipment, and errors which are introduced into a measurement signal due to performance variations in devices exposed to a harsh or accident environment (degraded insulation resistance).
As applied to a series of tests of a safety-related pump, the random uncertainty term l would be demonstrated as random scatter in the test results. Given sufficient test data, the actual random error for the tests can be determined. The random error l
term (repeatability of the test result) is controlled for ASME Section XI by requiring ;
use of instruments meeting accuracy requirements of 2% of full scale.
As applied to a series of tests of a safety-related pump, the bias uncertainYferm would be demonstrated as a constant offset in the test results. The magnitude of this offset would be difficult to predict from the test data. However, the impact of the bias is cancelled out by comparison to a baseline test.
If T, represents the test result combined with the bias error at some previous test, and T2represents the test result combined with the bias error from a future test, then:
T, = Actual Performance, + Bias T 2= Actual Performance 2 + Bias l T,
T2 In a baseline comparison, the safety-related pump performance is measured and compared to the baseline performance.
T2-T, = (Actual Performance 2 + Bias)-(Actual Performance, + Bias)
T2- T, = Actual Performance 2- Actual Performance, Since the bias error is constant, the camparison (trend) is a valid indication of actual pump performance. Terms that make up the bias error (orifice plate tolerances, tap locations, and process temperature) are constant. These constant bias terms are cancelled by the comparison of the test data to a previous baseline.
Finally, frequent verifications are provided to assure the capability of safety-related purnps. The combination of all these verifications provides a robust measure of the pump performance. Furthermore, ASME Section XI requires accurate instruments to
Attachment 1 to W3F1-99-0100
'.~ ,' ,' . Page 4 of 9 assure the test results are repeatable. Comparison of an IST test to the baseline is a powerfulindicator of a pump performance trend. The ASME Section XI tests reliably identify. pump degradation and provide strong assurance the pump will perform acceptably in service.
In conclusion, the ASME Section XI testing of safety-related pumps requires
. comparison to a baseline test, which cancels out the impact of the bias uncertainty terms, and requires use of accurate instruments to reduce the random uncertainty terms. ASME Section XI test results in combination with the Technical Specification surveillance requirements and other verifications of performance provide reasonable assurance safety-related pumps are capable of performing their specified safety function.
3.0 SAFETY RELATED PUMP PERFORMANCE EVALUATION Reference 2 evaluates the application of instrument uncertainty to ASME Section XI test results for specific safety-related pumps. This application of instrument uncertainty (which is different from instrument inaccuracy) to ASME Section XI test results is not required by regulation or ASME Section XI. (Reference 5) The evaluation in Reference 2 was an exercise conducted in response to an inspector's request concerning the impact if uncertainties were applied to ASME Section XI testing. The results of this evaluation demonstrate sufficient margin between the test acceptance criteria and the design limits to account for the instrument uncertainties (although not required), with the exception of the following:
. Auxiliary Component Cooling Water Pumps (ACC-MPMP-0001 A and B) l
. Component Cooling Water Pumps (CC-MPMP-0001 A, B and AB)
. Chemical and Volume Control Pumps (CVC-MPMP-0001 A, B and AB)
. Essential Chilled Water Pumps B and AB (CHW-MPMP-0001B and AB)
. Emergency Feedwater Pumps (EFW-MPMP-0001A, B and AB)
. High Pressure Safety injection Pumps (SI-MPMP-0002A, B and AB)
The evaluation showed, with the exception of those pumps described below, the latest Section XI test results also contain sufficient margin to account for uncertainties. Additional information is provided below to demonstrate that these pumps meet their specified functions with instrument uncertainties fully accounted for.
- 1. ACCW pump B - ACCW pump flow balance testing is not specified in the Waterford 3 Technical Specifications. However, EOl performs this testing at ,
Waterford to measure the cooling water flow in total and verify flow to the l ACCW/CCW, heat exchanger and Essential Chilled Water condensers remains l above the design basis limits. Testing has demonstrated the ACCW Pump B l delivered 5502 gpm total. This flow is above the design limit of 5350 gpm, but ;
does not provide sufficient margin to account for instrument uncertainty at a 95/95 ;
confidence level on the basis of flow measurement alone. l l
' Attachm nt 1 to
, , W3F1-99-0100 Page 5 of 9 Additional testing is performed in accordance with NRC GL 89-13 to verify the heat removal capacity of the ACCW/CCW heat exchanger (the ultimate function of the ACCW/CCW system). This testing includes provisions to account for instrument uncertainties and demonstrates the capability of the ACCW/CCW heat exchanger to meet its design basis safety function to remove the required heat load. In addition, the design basis inlet temperature for the chiller condenser cooling water is 105 F inlet at a flowrate of 850 gpm. The actual maximum Wet Cooling Tower water temperature is 90 F. At a temperature of 90 F, condenser cooling water flow uncertainty equates to 5 tons of cooling capacity, which is negligible when compared to the margin available to the assumed heat loads.
Thus, ample margin exists in the heat removal capability of the system to account for instrument uncertainty with the measured condenser cooling water flow.
Additionally, the exclusion of instrument uncertainty in ACCW flow testing was reviewed by the NRC Staff during the Engineering and Technical Support inspection conducted at Waterford 3 in December of 1997. (Reference 6) The Staffs resolution of this issue was provided in Reference 9. The Staff concluded that there was "no explicit regulatory or industry standards / requirements for the application of instrument uncertainties beyond Technical Specification parameters"."
In conclusion, the combined effect of GL 89-13 testing and flow balance testing provide reasonable assurance that the ACCW pump B can perform its safety function.
- 2. EFW pumps A, B, AB -The EFWTechnical Specification surveillance requirements include a pump performance test, which measures the pump discharge pressure on mini-recirculation. The basis for the test is to ensure the i pump performance is sufficient to meet the design flow requirements. The l
surveillance acceptance criteria require the pump to operate very close to the i certified pump curve. ASME Section XI testing of the EFW pump is also performed. The acceptance criterion for the Section XI test is the same as the Technical Specification surveillance acceptance criteria. Sufficient margin is available between the acceptance criterion and the arialytical limit to envelop the instrument uncertainty of the pump suction and discharge pressure. Although pump flow rate is also measured during the pump surveillance, flow instrument ,
uncertainty does not impact the surveillance results because the test is performed on mini-recirculation, where pump developed head is insensitive to flow. This differs from the conclusions presented in Reference 5 in that the previous evaluation unnecessarily considered the flow uncertainty at minimum recirculation flow.
Thus, the EFW Technical Specification surveillance requirement provides
'"" Refer to item (3) on page 4 of Reference 7
Attachm:nt 1 to W3F1-99-0100 Page 6 of 9 reasonable assurance that the EFW pumps can perform their safety function and properly considers instrument uncertainty.
- 3. HPSI pumps A, B, AB - Although the ASME Section XI test results did not have sufficient margin to the design limit specified in the IST Program to account for instrument uncertainty, the HPSI Technical Specification surveillance requirements currently demonstrate the capability to meet the HPSI design basis.
The HPSI design basis and surveillance requirement limits, including instrument uncertainty, have been previously evaluated by Condition Report 97-2695. This Condition Report identified a previous Technical Specification basis calculation (612752-MPS-5 CALC-001) prepared by ABB Combustion Engineering that assumed an instrument uncertainty value which was less than the instrument uncertainty determined by Waterford 3 calculation EC-195-011, "SI-HPSI Flow Instrumentation Calculation." The operability evaluation associated with Condition Report 97-2695 concluded that additional margin realized by utilizing a new, NRC approved Small Break Loss of Coolant Accident (SBLOCA) model more than compensated for the evaluated instrument uncertainty, in addition, a new SBLOCA analysis has been completed and submitted to the Staff in EOl's letter (W3F1-98-0090) dated April 30,199. This analysis incorporates a reduced High Pressure Safety injection (HPSI) flow to account for measurement instrument uncertainties and uses the new ABB Combustion Engineering S2M SBLOCA model, which was approved by the Staff on December 18,1997. The HPSI Technical Specification surveillance requirements contain sufficient margin to the new analysis to account for instrument uncertainties and provide reasonable assurance that the HPSI pumps can perform their safety function.
Conclusion The above discussion demonstrates that each of the pumps meets its ASME Section XI test requirements, satisfies the requirements of the Technical Specifications, and is capable of meeting its safety function. This conclusion is independent of the debate over whether instrument uncertainty is required to be considered in all of the cases discussed.
4.0 APPLICATION OF INSTRUMENT UNCERTAINTY EOl's position is that the application of instrument uncertainty is not required for ;
ASME Section XI testing of safety-related pumps. This is supported by Section 5.5.4 of NUREG-1482 and interpretations of ASME Code given in inquiries IN91-037 and IN91-3, issued March 10,1992.
ASME code interpretations and NRC guidance have not required the application of instrument uncertainty to ASME Section XI testing. As explained above,Section XI ,
requires consideration of instrument accuracy but not instrument uncertainties.
Under 10CFR50.55a, ASME Section XI provides the specific requirements M
q Attachment 1 to W3F1-99-0100 l
, Page 7 of 9
. applicable to inservice Testing of safety-related pumps.10CFR50, Appendix B Criterion Ill, " Design Control," and Criterion XI, " Test Control," set forth broader.
Quality Assurance standards, but do not address the application of instrument uncertainty to ASME Section XI testing of safety-related pumps. Paview of the Waterford 3 licensing bases does not reveal any commitment or requirement for generically applying instrument uncertainty to ASME Section XI testing of safety-related pumps.
ASME Section XI testing monitors for a change in pump performance. Pump performance is measured and compared to a reference baseline to detect degradation. As demonstrated in Section 2.0, many of the instrument uncertainty ,
terms (including orifice plate tolerances, tap locations, and process temperatures, l etc.) are eliminated when comparing test results to a previous test baseline. If pump 1 performance is consistent with previous tests and no degradation is evident, then the ASME Section XI test demonstrates the pump performance is satisfactory. Initial i startup testing or a subsequent baseline test establishes the basis for the original l conclusion of operability. Continued ASME Section XI testing demonstrates that pump degradation has not occurred, and basechn a comparison with the baseline '
test, demonstrates the pump continues to perform satisfactorily. l Branch Technical Position HICB-12 presents a new NRC position on instrument uncertainties as it relates to setpoints. It should be noted that the regulatory basis presented in HICB-12 only addresses setpoints involving limiting safety system l
- settings and settings for automatic protective devices having significant safety i functions. Ereeding the limiting safety system settings and settings for automatic 1 protective devices having significant safety functions may be considered a malfunction of an automatic safety system, which could impair the integrity of the ]
reactor core, reactor coolant pressure boundary, containment, and associated i systems. EOl explicitly applies instrument uncertainties for these limiting safety system settings at Waterford 3. However, EOl is concerned the NRC Staff's position stated in Reference 1 is inappropriately extending the application of instrument uncertainty beyond the position in HICB-12 to Technical Specification Limiting Condition for Operation limits and ASME Section XI testing results that have no setpoints associated with automatic protective action.
EOl is actively involved in industry efforts to define an acceptable grading technique for consideration of instrument uncertainties. Previous regulatory positions, for Waterford 3 and in licensing other facilities, appeared to have accepted a generalized method of addressing instrument uncertainty. In this approach, the discrete components, such as instrumeat uncertainties, were not evaluated on an individual basis but were included in an overall safety margin. However, recent regulatory positions have favored the evaluation of the discrete components on an individual basis and expressed dissatisfaction with using an overall safety margin to i account for instrument uncertainties. This results in unnecessarily excessive margin being required to accommodate the multitude of individual uncertainty components all applied in the worst direction at the same time. (Reference 8)
I
Attachment 1 to
, , Page 8 of 9 EOl has extensively researched these issues and has participated on numerous industry meetings and discussions on the application of instrument uncertainty.
Many of these discussions and meetings included the NRC Staff. We have developed a graded approach to address the application of instrument uncertainties, including Technical Specification Limiting Conditions for Operation and surveillance -
tests. This graded approach, consistent with BTP HICB-12, explicitly incorporates a rigorous treatment of instrument uncertainty for Technical Specification Limiting Conditions for Operation and surveillance variables where the magnitude of the uncertainty could have a significant impact on the performance of a ' safety function.
For example, limiting safety system settings at Waterford 3 include full instrument uncertainty. This graded approach is summarized in Reference 9.
Conclusion Application of instrument uncertainty to ASME Section XI testing is not required by the ASME code or NRC regulations. Furthermore, in the absence of specific regulatory requirements or guidance, EOl has developed guidance for a graded s
approach to the application of instrument uncertainty to Technical Specification Limiting Conditions for Operation. This approach requires rigorous treatment of instrument uncertainties for significant variables such as limiting safety system settings. For other variables where adequate margins exist to ensure the safety function is met, a more reasonable treatment is appropriate. This approach recognizes that adequate margin can exist in the overall result without the need to i explicitly acccunt for discrete uncertainties in each individual component.
Actions Taken or Planned Actions taken to address instrument uncertainties include those previously addressed in EOl's submittals to the NRC Staff (References 9-12). These documents detail the guidance for applying instrument uncertainty at Waterford 3 and review of the Waterford 3 Technical Specification Limiting Conditions for Operation, which assured appropriate considerations of instrument uncertainty are provided?
' Reference 5 communicates the completion of the PIP item for the TS-LCO/SR Uncertainty Project l
y Attachm:nt 1 to l
. . W3F1-99-0100 l
. Page 9 of 9
5.0 REFERENCES
- 1. NRC letter from R. W. Borchardt, Deputy Director Office of Enforcement to Charles M. Dugger, Vice President Operations -Waterford 3, " Reconsideration of Enforcement Actions (EA 98-022)," May 24,1999.
- 2. Waterford 3 Engineering Request (ER-W3-99-0428-00-00)," Application of instrument Uncertainty to Safety Related Pump IST Results and Comparison to Design Basis Limits," April 27,1999.
- 3. NRC letter from Dale Powers, Engineering and Maintenance Branch Chief-Division of Reactor Safety, to Charles M. Dugger, Vice President Operations - ,
Waterford 3, "NRC Inspection Report No. 50-382/99-06," May 18,1999. l l
- 4. NRC letter (SECY-99-014) frcm William D. Travers, Executive Director for Operations, to the Commisioners of the NRC, "Rulemaking Plan: Revision of Appendix K to Title 10, Part 50, of the Code of Federal Regulations (10 CFR Part 50)," January 13,1999.
- 5. NUREG-1482, " Guidelines for Inservice Testing at Nuclear Power Plants," April, 1995.
- 6. NRC letter from Arthur T. Howell I!I, Director Division of Reactor Safety, to Charles M. Dugger, Vice President Operations - Waterford 3, "NRC Inspection Report 50-382/97-25 and Notice of Violation," March 12,1998.
- 7. NRC letter from Ellis W. Merschoff, Regional Administrator, to Charles M.
Dugger, Vice President Operations - Waterford 3, " Notice of Violation and Proposed Imposition of Civil Penalty - $110,000 (NRC Inspection Report No.
50-382/97-25)- and Exercise of Enforcement Discretion (Vll.B.6)," June 16, 1998.
- 8. NUREG-0133," Staff Discussion of Fifteen Technicalissues Listed in Attachment to November 3,1976 Memorandum from Director, NRR to NRR Staff," November 1976.
- 9. Waterford 3 letter (W3F1-99-0053) to NRC Document Control Desk, "Entergy Commitments on Instrument Uncertainty," March 31,1999.
- 10. Waterford 3 letter (W3F1-98-0078)io Mr. T. Stetka, Acting Engineering Branch Chief, "E&TS Enforcement Conference Follow-up Items," May 7,1998.
- 11. Waterford 3 letter (W3F1-98-0080) to NRC Document Control Desk, " Technical Specification Change Request NPF-38-206 Emergency Feedwater System,"
May 28,1998.
- 12. Waterford 3 letter (W3F1-98-0090) to NRC Document Control Desk, "Small Break Loss-of-Coolant Accident Emergency Core Cooling System Performance Analysis Using the ABB/CE Supplement 2 Model," April 30,1998.