ML20206Q283
| ML20206Q283 | |
| Person / Time | |
|---|---|
| Issue date: | 05/05/1999 |
| From: | Racquel Powell NRC OFFICE OF ADMINISTRATION (ADM) |
| To: | Bird P NRC OFFICE OF PERSONNEL (OP) |
| Shared Package | |
| ML20206Q280 | List: |
| References | |
| NUDOCS 9905190092 | |
| Download: ML20206Q283 (4) | |
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p 1 UNITED STATES I p j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20066 4 001
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mar -$ m MEMORANDUM TO: . Paul E. Bird, Director Office of Human Resources A ff -
SUBJECT:
DIFFERING PROFESSIONAL OPINION FROM FREDERICK BURROWS (DPO-99-1)
By memorandum dated April 1,1999, you requested that my office coordinate the review for the release of records, in accordance with NRC Management Directive 10.159, relating to a Differing Professional Opinion (DPO), "Use of Allowable Values in Technical Specifications,"
(DPO-99-1) and for placement in the Public Document Rom (PDR). The review of the subject records has now been completed.
The records identified on the enclosed Appendix should be placed in the PDR and NUDOCS by your office The records behind Tab.A should be placed directly in the PDR. The records behind Tab B should be mailed to the Document Control Desk for NUDOCS processing and distribution to the PDR. Because several enclosures to record 1 are copyrighted, these enclosures are not included in the NUDOCS set of records, but are included with the records for placement in the PDR (Tab A).
The records behind Tab C contain the background memoranda relating to the processing of this DPO by my office. These records should be included with the official DPO file for which your office will transmit to the NRC File Center.
Attachments: As stated P ap 3 QO p PDR
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,Y DPO 99-1 APPENDIX NO. DATE DESCRIPTIONHPAGE COUNT)
- 1. 10/31/97 Memorandum to B Sheron and R Zimmerman,
Subject:
Follow-Up Actions to NRR Ad-Hoc Review Panel on the Differing Professional View on Technical Specification Trip Setpoints and Allowable Values for Instrumentation (45 pages)(ENCLOSURES 5,6,7, AND 8 ARE COPYRIGHTED AND AVAILABLE FOR VIEWING ONLY AT THE PDR)
- 2. 2/19/98 Memorandum to F Burrows from S Collins,
Subject:
Actions to Address Differing Professional Views (1 page) attaching 1/5/98 Memorandum to B Sheron from R Spessard,
Subject:
Use of Mesac in Braidwood (4 pages)
- 3. 6/4/98 Memorandum to F Bunows from L Callan,
Subject:
Request for Review of Concerns Related to Technical Specification Setpoints and Allowable I Values for Instrumentation Under Formal Differing Professional Opinion Procedures (1 page); 6/4/98 Memorar.dum to S Collins from L Callan (1 page); 5/21/98 Memorandum to L Callan from F Burows (2 pages)
- 4. 7/24/98 Memorandum to L Callan from S Collins,
Subject:
Differing Professional View and Differing Professional Opinion Regarding Technical Specification Setpoints and Allowable Values for Instrumentation (2 pages); 7/24/98 Memorandum to F Burrows from S Collins (3 pages) ;
6/22/98 Memorandum to S Collins from B Sheron (7 pages) j
- 5. 8/11/98 Memorandum to P Bird from L Callan,
Subject:
Additional Comments on
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the DPO/DPV Process (1 page): 8/5/98 Memorandum to L Callan from F Burrows (9 pages)
- 6. 8/1.J98 Memorandum to F Burrows from L Callan,
Subject:
Request for Review of -
Concerns Related to Technical Specification Setpoints and Allowable i Values for Instrumentation Under Formal Differing Professional Opinion j Procedures (1 page)
- 7. 8/24/98 Memorandum to M Federline and C Rossi from L Callan,
Subject:
Differing Professional Opinion Concerning Technical Specification Set Points and Allowable Values for Instrumentation (1 page)
R. 9/28/98 E-Mail from J Mitchell to M Federline,
Subject:
DPO Panel re: Setpoints (1 page) l l
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- 9. 11/19/98 Memorandum to W Travers from M Federline,
Subject:
Status of Review of Differing Professional Opinion Concerning Technical Set Points and Allowable Values for instrumentation (1 page)
- 10. 12/29/98 E-Mail from M Federline to F Burrows,
Subject:
Completion of Panel Review of DPO on Technical Specification Set Points and Allowable i Values (1 page) l
- 11. 12/30/98 E-Mail from F Burrows to M Federline,
Subject:
Completion of Panel Review of DPO on Technical Specification Set Points and Allowable Values (1 page)
- 12. 2/16/99 Memorandum to F Burrows from W Travers,
Subject:
Final Decision:
Differing Professional Opinion on Technical Specification Setpoints and Allowable Values for instrumentation (2 pages); 1/15/99 Memorandum to )
W Travers from M Federline (1 page) Ad Hoc Review Panel Report (9 pages); 2/16/99 Memorandum to S Collins from W Travers (1 page);
12/17/98 Memorandum to M Federline from L Chandler (1 page) ;
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h UNITED STATES g j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 205&M001 o% *****/ October 31, 1997 MEMORANDUM TO: Brian W. Sheron, Actibg Associate Diredor l
For Technical Review Office of Nudear Reador Regulation Roy P. Zimmerman, Assodate Director For Projects Office of Nudear Reactor Regulation FROM: Director '
Office of Nudear Reactor Regulation
SUBJECT:
FOLLOW-UP ACTIONS TO NRR AD-HOC REVIEW PANEL. ON THE l DIFFERING PROFESSIONAL VElW ON TECHNICAL SPECIFICATION l TRIP SETPOINTS AND ALLOWABLE VALUES FOR l lNSTRUMENTATION in a memorandum dated March 17,1997, a differing professional view was expressed regarding j Technical Specifications (TS) trip setpoints (TSPs) Lnd allowable values (AVs) for l Instrumentation. The Ad-Hoc NRR Review Panel reviewed the concoms addressed in the i differing professional view and their report is endosed.
The review identified the following recommendations:
(1) Following appropriate staff review of the Panel's findings, the staN should hold a public meeting with the NSSS Owners Groups to, (1) provide the NRC staff position that 10 CFR 50.36 requires the TSP to be the Umiting Safety System Setting (LSSS), (2) discuss the staN position on the use of TS Bases to comply with TSP limits, and (3) discuss the need to revise the NRC's improved Standardized Technical Specifications (ISTS) accordingly. (ADP/ADT)
(2) Following the meeting with the industry, the staff should initiate actions necessary to update the ISTS in accordance with agency procedures (i.e.' 50.109) for new staff positions to incorporate TSPs in the Umiting Conditions for Operations (LCO)
Tables, consistent with the requirements for LSSS required by 10 CFR 50.36.
(ADP/ADT)
(3) The staff should meet with the licensees for the nine plants that have converted to the ISTS by relocating TSPs to licensee controlled documents to discuss means to bring their TS into compliance with 10 CFR 50.36 as discussed in Recommendations 1 and 2 above. (ADP/ADT)
(4) The staff should ensure that TS Bases do not inappropriatety suggest that protective devices could be adjusted beyond the TSP limits. The staN should provide guidance to licensees on compliance with TSP limits, with emphasis on those situations where the TS Bases state that channels are considered operable when a TSP limit is
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exceeded by a tolerance that was treated as an instrument uncertainty in the establishment of the TSP. Because Westinghouse has indicated that this practice was intended for Westinghouse plants licensed since 1981, this guidance is not restricted to plants that have converted to the ISTS with the Bases statement noted above, it is recommended that the staffissue's generic communication to address the following: (ADP/ADT)
- a. Guidance on adjusting setpoints to comply with the TS limits.
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Guidance on TS changes for a licensee amendment request that could be submitted and that would incorporate a calibration tolerance or allowance for adjusting trip setpoints to satisfy the specified TSP limits.
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(5) The staff should develop a plan providing the proper emphasis on TSPs in the ISTS Bases versus the cuaent emphasis on the use of AVs for operability determinations.
(ADP)
(6) The staff should assure consistency between the Paners findings on TSPs and AVs and the next revision of RG 1.105. The staff should review documents for instrumentation setpoints, specifically Branch Technical Position (BTP) PSB-1, and to modify them as necessary to reflect the findings of the Panel. (ADT)
(7) The technical staffin Headquarters and the Regions should be informed of the staff's actions on the Paners findings as appropriate. (ADP/ADT)
(8) The staff should review procedures and guidance for NRR Project Managers on handling licensing actions to ensure that clear guidance is provided for establishing due dates and identifying appropriate technical branches with review responsibility.
(ADP)
Please provide your response to me withing 45 days on (1) the actions proposedtto be taken to address the Panel's recommendatons and (2) the schedule for completing tho*e actions.
Enclosure:
As stated
AD-HOC REVIEW PANEL REPORT ON THE DIFFERING PROFESSIONAL VIEW .
OF MR. FREDERICK BURROWS ,
/b/3//77 Zim an, Chair Ad-Hoc Review Panel W /"Mr7 Bruce A. er, Member Ad-Hoc Review Panel I) D 7
( ( /l Thomas G. DunninJ, Member Ad-Hoc Review Panel l
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EXECUTIVE
SUMMARY
in s memorandum dated March 17,1997, the differing professional view of Mr. Fred Burrows, an i electdcal engineerin the Eledrical Engineering Branch (EELB), was forwarded to the Director, l NRR, regarding Technical Spedfications (TS) trip setpoints (TSPs) and allowable values (AVs) for instrumentation. An ad-hoc review panel, appointed by the Director, NRR, through a memorandum dated March 24,1997, was formed to review the differing professional view and make recommendaCons based on its findings. The members of the Ad-Hoc Review Panel were Roy Zimmerman as Chair, Bruce Boger as a management member, and Tom Dunning as a staff member as recommended by Mr. Burrows. Anthony Mendiola served as technical assistant to the Panet.
Mr. Burrows provided two concems. The first concem is that 10 CFR 50.36," Technical Specifications," requires the TSP by itself be considered the Umiting Safety System Setting (LSSS), and a closely related second concem is that the NRC Improved Standard Technical Specifications (ISTS)'should focus on the TSP, not the AV, since it is only the TSP that accounts for all known instrument errors. '
The Panel conducted meetings with Mr. Burrows and members of the following branches:
Instrumentation and Controls Branch (HICB)l Technical Specification Branch (TSB) and EELB.
Additional discussions were held with senior members of the Office of General C and the Office of Enforcement (OE).
Mr. Burrows identified the concems that TS which do not include TSPs (i.e., NRC's actions on the TS for nine of the eleven facilities that converted to the format of the ISTS) are incon with the regulatory requirements for LSSS and the associated TS Bases have emphasized the importance of AVs in lieu of providing appropriate emphasis on the importance of TSPs in establishing instrument operability. The Panel found that these conoems are primarily administrative in nature (i.e., related to compliance with 50.36) and do not adversely affect the safe operation of reactors that are subject to TS requirements that do not include TSPs.
Additional concems were developed during discussions with Mr. Burrows and subsequent Panel deliberations. Likewise, the Panel found that the issues identified during these discussions and delibe ations do not adversely affect the safe operation of reactors due to TS requirements I associated witt, those iss'7s.
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1 The following summarizes the Paners findings on the concoms raised during its review.
Recommendations are provided after the discussion of the findings in the body of the report. The
' first two concems are from Mr. Burrows' mornorandum, the next four concoms were raised by Mr. Burrows during discussions with the f%el, and the Panel developed the remaining four concems during its deliberations.
- 1. The Panel considered the concem that plant TS that are based on the ISTS that include and designate AVs as LSSS, in lieu of TSPs, are inconsistent with requirements for LSSS as stated in 10 CFR 50.36. Further, Regulatory Position 3 in the staffs draft Regulatory Guide DG-1054, the proposed Revision 3 to Regulatory Guide (RG) 1.105, " Instrument I
ISTS is defined as the current version of the NRC's Standard Technical Specdestons. STS refers to the prehus versions of the Standard Technical SpecMestions.
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Setpoints for Safety Related Systems," which states that AVs must be specified in the TS to meet 10 CFR 50.36, is similarly inconsistent with those requirements. ,
l The Panel found this concem to be complex and its resolution required considerable discussion with members of the technical and legal staffs. The Panel found that both TSPs and AVs are important in deterrhining instrument operability. In addition, the approach and treatment of TSPs and AVs have not been consistent in industry and regulatory guidance, since over time either one or both have been deemed to be the LSSS. The Panel recognized that the 10 CFR 50.36 requirement for an LSSS to be a setting "so chosen that automatic protective scuon will correct the abnormal situation before a safety limit is exceeded" could reasonably be considered to apply to either TSPs or AVs in the context that those terms have meaning with regard to the operability of an associated channel. However, the Panel concluded that the LSSS is that setting for en automatic protective device that is manually adiusted so that the device willinitiate an automatic protecuve action and that setting is the TSP. Therefore, the Panel agrees with Mr. Burrows that M is the TSP, not the AV, that satisfies the regulatory requirement for the LSSS. (in contrast, the AV is not a setting that is used to adjust a protocuve device to initiate an automatic protective scuon. Rather, the AV is the limiting 'as fouruf" value of an observed protective device setting thst due to changes over time, primar9y instrument drift during the surveillance interval, would not exceed the allowances for such uncertainties used to establish the value of a TSP and that, at the time it is observed, satisfies the the operability goal of the regulatory requirement for the LSSS. That goal is an automatic protocuve acDon that would correct an abnormal situation before a safety limit is exceeded.) in addition, the Panel found that 10 CFR 50.36 does not provide a sufficient regulatory basis for NRC to require AVs to be included in the ISTS or plant TS as stated in the staffs draft of Revision 3 to RG 1.105 WG 1054).
2.
The Panel considered Mr. Burrows' concem that the ISTS should focus on th!
left" values) not on the AVs. It is his opinion that an instrument channel can only be l
considered operable if it is adjusted to the TSP within the calibration to'eTE.cs specified in the essociated setpoint calculations since it is only the TSP (not the AV) that accounts '
for all the instrumentation errors, and it is so chosen that automat!c protective scuon will correct the abnormal situation before a safety limit is exceeded.
As noted above, the Panel acknowledges the importance of both TSPs and AVs in the deteHnation of instrumentation operability. However, the Panel found that only the TSP satisfiw the requirements of 10 CFR 50.36 for the LSSS. In addition, because the TSP is used to adjust protocuve devices during surveillances, the Panel agrees with Mr. Bumms that the ISTS Bases have not placed sufficient emphasis on the importance of the TSP in i 99 tit t't.g operability during surveillances and its use in operability determinations.
During Panel discussions with Mr. Burrows, four additional concoms were brought forth. They are summarized as follows:
3.
The Panel considered Mr. Burrows' concem that TS values should be stated as a value with a i percent tolerance to provide a more precise setpoint. This format for TSPs is currenuy used for electrical system loss of voltage and undervoltage trip functions. Mr.
Burrows' believes that this TSP format should also be used in lieu of that currently used for instrumentation system trip functions that are values stated as a single sided bounding limit with s or 2 notation.
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The Panel found that the use of single sided bounding limits for TSPs is consistent with the regulatory requirement for the LSSS. The Panel could not identify a regulatory basis for imposing TSPs expressed as a
- tolerance. Therefore, the Panel disagrees that TSPs should be stated as a value with a
- tolerance in lieu of a single sided bounding limn. <
- 4. The Panel considered Mr. Burrows' concem that Technical Branch (TB) preparation of Safety Evaluation Reports (SERs) that involve setpoint changes have been requested by MRR Project Managers (PMs) with unrealistic due dates. Additionally, Mr. Burrows raised a concem about those instances where a PM drafts the SER and TB concurrence has been requested by the PM with an unrealistic due date.
The Panel found that due dates should be discussed with and agreed upon by the TB before the start of work in accordance with NRR Office Letter 803. !
5.
The Panel considered Mr. Burrows' concems that there had been instances where l Project Managers (PMs) had (1) reviewed and accepted licensees' amendment requests for TSP changes without seeking the review or concurrences of the TB with the primary '
responsibility for the review of the TSP being changed, or (2) requested reviews or concurrences by a TB that did not have the primary responsibility for the TSP being l changed.
The Panel concluded that PM reviews of license amendments are Justified where the has sufficient technical knowledge to perform an evaluation of TSP changes. The Panel notes that PM reviews have been a significant factorin reducing the backlog of open licensing actions. However, the Panel also found that PMs should .aquest concurrence from the appropriate TB to ensure that the evaluation is consistent with current practice.
6.
The Panel considered Mr. Burrows' concem that there are NRC setpoint methodology documents for reviewers (specifically BTP PSB 1) that are inconsistent in the guidance provided for reviews of this area.
The Panel found that BTP PSB-1 is inconsistent with the ISTS.
The Panel developed four other related concems durin,- its review.
- 7. The Panel developed and considered the concem that the NRC needs to confirm that processes are in place to control changes to T8Ps where only AVs are included in the T8.
The Panel reviewed a sample of the staffs SERs for TS amendments that proposed to relocate TSPs to licensee controlled documents and noted that the SERs had stated the staff's finding that adequate controls (10 CFR 50.5g) were in place for any subsequent licensee change to TSPs that would be relocated. Based on discussions with the Lead Reviewers for the remaining SERs for TS amendments that proposed to relocate TSPs to licensee controlled documents, N was confirmed that similar findings were made, in those SERs, with regard to the existence of adequate controls for any subsequent changes to TSPs that would be relocated.
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l Inspections conducted by TSB for the Cvystal River (the first TS conversion) verified that the TSPs were relocated to licensee controlled documents that are subject to the change controls of 10 CFR 50.59. Subsequent inspections for TS conversions are being performed by Regional personnel using the guidance in the NRC Inspection Manual (Tl 2515/130, " improved Standard Technical Specification Implementation Audits") that includes audits for verification of relocated requirements as follows:
- a. Verify that a sample of TS requirements listed as relocated in the licensee conversion submittal were relocated to the specified location.
b.
For those requirements sampled above that were relocated and subsequently modified, again relocated, or deleted, ensure, in accordance with Section 03.01.b.1, that the appropriate controls were used.
The Panel found that there are sufficient provisions within the NRC inspection program to confirm that processes are in place to adequately control changes to TSPs, in the interim, where only AVs are included in the TS. For the long term, the Panel's recommendations address restoring TSPs to TS consistent with the Panel's finding noted in item 1 above.
8.
The Panel developed and considered the concem whether the NRC has adequate assessment tools in place to verify that licensees are adequately determining instrumentation setpoints.
The Panel found that the staff has the necessary regulatory tools (e.g.,10 CFR 50.54(f)
Letters and the ongoing Architect / Engineer Design Team inspections) to provide information to assess licensee setpoint methodology and to ensure that appropriate findings are made on licenses practices in this area.
- 9. The Panel developed and considered the hypothetical question of what action the ISTS would require if a licensee identified an "as found" setting that was less conservative than the TSP.
The Panel examined the ISTS for all four NSSS Vendors and found that the requirements related to protective device settings are expressed in terms of requiring and demonstrating operability and that specLk requirements are not set forth with regard to TSPs or AVs. ~hus, or" must rely on the gtidanw in the TS Sases on TSPs and AVs to obtain the proper application of operability requirements for protective device settings.
Based on the majority of the statements included in the ISTS Bases for Reactor Trip System instruments, the panel concluded that an "as found" setting that is less conservative than the TSP would be adjusted consistent with the TSP.
Following discussions with the management and staff of TSB and HICB, the Panel also found that there was a consensus based on staff experience that licensees would adjust an "as found" value that exceeds a TSP to a value consistent with the TSP.
Nevertheless, the Panel found the statements in the ISTS and its Bases lack clarity and specificity with regard to the relationship between operability and the use of TSPs and AVs.
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The Panel developed and considered the hypothetical question of what action the ISTS would specify if a licensee identified an "as left" setting that was inadvertently left less conservative than the TSP. J 4
The Panel found that a channel would be inoperable since its surveillance requirements would not have been met since the "as left' setting was less conservative than the TSP.
Action would have to be taken to restore the channel to operable status by adjusting its ,
setting to a value that is equal to or conservative with its TSP or other remedial actions such as placing the channelin trip would have to be taken as stated in the TS. The '
Panel also found that the required actions are independent of whether or not the "as left' I value had exceeded its AV.
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INTRODUCTION in a mornorandum dated March 17,1g97, the differing professional view of Mr. Fred Burrows (See Enclosure 1), an electrical engineer in the Electrical Engineering Branch (EELB), was forwarded to the Director, NRR, regarding Technical Specification (TS) trip setpoints (T allowable values (AVs) for instrumentation. An ad-hoc review panel, appointed by the Dire NRR, through a memorandum dated March 24, igg 7 (See Enclosure 2), was formed to review the differing professional view and make appropriate recommendations. The members of the '
Ad-Hoc Review Panel were Roy Zimmerman as Chair, Bruce Boger as a management m and Tom Dunning as a staff member as recommended by Mr. Burrows. Anthony Mendiola served as technical assistant to the Panet.
Mr. Burrows provided two concems. The first concem is that 10 CFR 50.36, " Technical Specifications," requires the TSP by itself be considered the Limiting Safety System S (LSSS), and a closely related second concem is that the NRC Improved Standard Technical 4 Specifications (ISTS)8 anould focus on the TSP, not the AV, since it is only the TSP that accounts for all known instrument errors.
The Panel conducted meetings with Mr. Burrows and members of the following branches:
Instrumentation and Controls Branch (HICB), Technical Specification Branch (TSB) and EE l
Additional and the Office of discussions Enforcement (OE). were held with senior members of the Office of This repo4 provides relevant backgroused information, reviews ofidentified concems and developeo !: sues, and the Panel's recommendations. Enclosure 3 provides a listing of documents reviewed by the Panel. Enclosure 4 provides a historical summary of the requirements for Limiting Safety System Settings (LSSS), trip setpoints (TSPs), and allowable values (AVs) as contained in the (1) the Code of Federal Regulations, (2) Standard Technical
' Specifications (STS), and (3) industry and NRC guidance on TSPs and AVs that was Panel as background material for the discussion of the issues provided in this report. The Pa notes that the meaning and method for determining an AV as addressed in the industry guid have changed over time. For its deliberations, the Panel used the AV as it was defined at the time that the NRC issued its guidance on TSPs and AVs (RG 1.105, Revision 2, " Instrument Setpoints for Safety-Related Systems," issued February 1g86).
BACKGROUND A. Defined Terms This section provides definitions for key terms used throughout the report.
2lSTS is denned as the current version of the NRC's Standard Technical Speedications e
S previous versions of the Standard Technical Speedications.
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Allowable Value (AV)- As defined in the Instrument Society of America (ISA) Standard, ISA-867.04-1994', "Setpoints for Nuclear Safety-Related instrumentation," is the limiting value that '
the trip setpoint may have when tested periodically, beyond which appropriate action must be taken.'
Trin setnoint (TSP)- As defined in ISA-S67.04-1994, a predetermined value for actuation of the final setpoint device to initiate a protective action.
Umitina safety svntem Settina (LSSS)- As defined in 10 CFR 50.36(c)(1)(ii)(A), Umiting Safe System Settings for nuclear reactors are settings for automatic protective devices related to those variables having significant safety functions. Where a limiting safety system setting is specified for a variable on which a safety limit has been placed, the setting must be so chosen that automatic protective action will correct the abnormal situation before a safety limit is exceeded.
As Found Value - As defined in ISA-S67.04-1994, the condition in which a channel, or portion of a channel, is found after a period of operation and before recalibration (if necessary).
As Left Value - As defined in ISA-S67.04-1994, the condition in which a channel, or portion of a channel, is left after calibration or final setpoint device setpoint verification.
Safetv Umit (SD - As defined in 10 CFR 50.36 (c)(1), Safety Umits for nuclear reactors are limits upon important process variables that are found to be necessary to reasonably protect the integrity of certain of the physical barriers that guard against the uncontrolled release of radioactivity.
Analvtical Umit (AD - As ' defined in ISA-S67.041994, the limit of a measured or calculated variable established by the Safety Analysis to ensure that the Safety Umit is not exceeded.
Additional information on this terminology is contained in Enclosure 4 of this report. The relationships between these ds Sitions are shown on Figure 1 of the ISA Standard. A copy of this figure from the 1982,1988, end 1994 versions of the ISA Standard is provided in Enclosures 5,6, and 7, respectively.
- This standard is currently under consideration by the NRC for endorsement via Draft Regulatory Guide (RG) DG-1045, "Setpoints for Safety-Related instrumentation (Proposed Revision standard. 3 to RG 1.105)." The current version of RG 1.105 endorses the 1982 version of the
- The 1982 version of the ISA Standard identifies the AV by how it is determined, i.e., as differing from the TSP by the drift in that portion of the instrument channel which is tested when the setpoint is determined. The 1988 version of the ISA Standard increased the instrument uncertainties used to determine the allowance between the TSP and AV to include instrument calibration uncertainties and instrument uncertainties during nont,41 operation, in addition to instrument delft as specified in the 1982 version. Also, the 1988 version included the AV as a defined term stating that the instrument channel is declared inoperable during a surveillance when an AV is exceeded, but removed this clarification in the 1994 version of the AV stated above.
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B. Technical Snacification Reauirements This section provides a brief summary of the requirements for LSSS, TSPs, and AVs as sp in STS and used as a model for the TS of operating nuclear power plants.
The earty drafts of the STS for Westinghouse Pisnts, NUREG-0452, (circa 1974) had a section (
on LSSS under Chapter 2, " Safety Limits and LSSS." This section specifierf that the Reactor Trip System (RTS) instrumentation setpoints shall be set consistent with the TSP values shown in Table 2.2-1. Actions required the adjustment of the setpoint consistent with the TSP value when it was less conservative than the value specified in the table.
Administrative Controls in the earty versions of the STS, and in plant TS at that time, imposed a requirement for an abnormal occurrence report (subsequently called a licensee event report) whenever an instmment channel was found to be inoperable. Consequently, a large number of !
reports were required because normalinstrument drift caused setpoints to change during a surveillance surveillance wasinterval such performed. that the "as found" value often exceeded the TSP when the next '
Subsequent changes to the draft STS proposed in the fall of 1975 added AVs to Table 2.2-1 for the RTS functions. The AV was determined by adding the channel uncertainty due to instrument drift to the TSP value. Thus, a RTS channel would be capable of performing its safety function when the "as found" value of a protective device setting exceeded the TSP, so long as it did not exceed the AV, i.e., Iristrument drift did not exceed the allowance for this uncertainty that was used to determine the TSP. However, the instrument setting would be adjusted so that the "as left" value did not exceed the TSP as specified by the LSSS specification for the RTS, or as specified by the LCO for the ESFAS instrumentation. This action, adjusting the setpoint to not exceed the TSP, restores the margin for instrument drift that may occur over the next surveillance interval.
When AVs were added to the STS..new actions specified the remedial measures to be taken when a setpoint exceeded the AV. The new actions were to (1) declare the channelinoperable and (2) apply the applicable action statement requirement of Specification 3.3.1.1 (the Limiting Condition for Operation for the RTS), until the channel is restored to OPERABLE status with its setpoint adjusted consistent with the TSP. Tin latter action, adjusting the setting to restore the channel to operable status, would be taken as part of c surveillance that determined that the protective device setting exceaed its AV. NUREG-0452 was finalized and issued in June of 1978.
With the addition of AVs to plant TS, a basis was provided for a finding that a channel was operable when its setpoint was found to exceed the TSP but not the AV. This significantly reduced the number of abnormal occurrence reports that licensees had to submit when lastrument drift, which occurs during the surveillance interval, caused a setpoint to be found that exceeded its TSP.
In September 1992, the ISTS were issued as a st. ries of NUREG documents (14301434) for each of the Nuclear Steam Supply System (NSSS) vendors. Changes were proposed by the vendor Owner's Groups and subsequently reviewed and approved by the staff. Changes were made in the manner that h.stpoint requirements were specified. The section on LSSS for the RTS was removed and the setpoint table was moved to the LCO for the RTS. The LCOs for the 9
RTS and ESFAS were changed to specify that the associated instrumentation shall be op but without the earlier reference to the adjustment of setpoints consistent with the TSP.
For NSSS vendors other than Westinghouse (W), the tables for the RTS and ESFAS LCOs liste only the AVs and not the TSPs. For these non W NSSS vendors, the ISTS Bases state that the Avis the LSSS.
- The ISTS for Westinghouse plants include both TSPs and the AVs. However, a footnote for the TSP column of the LCO Table provides the option, on a unit specific implementation basis, to include only AVs. The associated Bases states that the TSP is the LSSS, but with TSP in brackets to indicate that it may be di#erent on plant specific basis, i.e., N could be the AV if the TS Table used a single column format that did not include TSPs.
C. riimme lan of Mr. Burrows' Concams This section provides a summary of the concems raised by Mr. Burrows that led to the statement of his differing professional view, expressed the concem that the recent sta# e# orts to improv Standard Technical Specifications have undermined efforts in the 1980's to produce a meaningful and technically concise approach to satisfy 10 CFR 50.36. Specifically, it was his opinion that the use of an AV to determine operability for an instrumentation channelin lieu of the channel's TSP in TS does not satisfy 10 CFR 50.36 and is not consistent with actual plant calculations setpoints. that establish setpoints and with plant procedures that maintain the validity of those In their response dated April 2,1996, C. Grimes and J. Wermiel stated that it was not clearif Mr.
Burrows had raised a particular technical concem or policy concem regarding the appropriate means to reflect setpoint calculations and related maintenance practices into TS requ!rements.
They also requested that Mr. Burrows document his concems so that they oould be addressed before a revision to Regulatory Guide 1.105, " Instrument Setpoints for Safety Systems," or further changes to the ISTS were made, in a memorandum to J. Wem11el and C. Grimes dated August 9,1996, Mr. Burrows provided I .2 comments on the proposeo Revision 3 to Regulatory Guide 1.105. In addition, Mr. Burrows questioned whether the staff was consistently r.pp/, rig 10 CFR 50.36 and stated that the staff was hr,s./c.g the importance of the TSP and that the TSP is the only setting that will satisfy 10 CFR 50.36. In a response of August 29,1996 C. Grimes and J. Wermiel stated that Mr.
Bumms' comments would be considered along with those obtained from the public.
When M appeared to him that his comments and those made by Westinghouse (letter to the NRC dated December 19,1996), would produce no change in the staff's approach to the importance of a channers TSP, Mr. Burrows stated his differing professional view in a memorandum to his supervisor dated March 17,1997. He addressed two concems as stated below.
1.
Regulatory Position 3 in the staff's draft Regulatory Guide DG 1045 (Proposed Revision 3 to Regulatory Guide 1.105, circa October 1996) states that "the allowable value, in conjunction with the trip setpoint, will determine the limits on instrument operability and 10 l
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must be specified in the TS in order to meet 10 CFR 50.36. The LSSS should be developed in accordance with the setpoint methodology based on the standard, wtRh the 1 allowable value listed in the TS and the relationship of the trip satpcint to the allowable !
value must be documented and controlled by the setpoint methodology."
However,10 CFR 50.36 states that TS willinclude LSSS and "where e limiting safety system setting is specified for a variable on which a safety limit has been placed, the setting must be so chosen that automatic protective action w1 correct the abnormal i'
situation before a safety limit is exceeded." In a typical setpoint methodology for instrumentation, N is only the TSP that satisfies this requirement since its'value (not the ;
AV) accounts for all the instrumentation errors. This is supported by ISA-S67.06-1994, "Setpoints for Nuclear Safety Related instrumentation." ,
i Further, the standard states that "an allowance shall be provided between the trip i setpomt and the analytical limit to ensure a trip before the analytical limit is toached" and "the trip setooint should be the value that the f! 'setpoint device is set to actuate."
i Therefore, it is Mr. Burrows' view that 10 CFR 50.36 requires the TSP by itself be ;
considered the LSSS. '
2.
In the TS for Westinghouse plants issued in the 1980's, an LCO for safety-related instrumentation would typically state that an instrument channel was operable if its j setpoint was set consistent with values shown for the TSPs. Contrary to this, the current Westinghouse ISTS states in the Bases that "if the measured setpoint does not exceed the allowable value, the bistable is considered operable." It is Mr. Burrows' opinion that l an instrument channel can only be considered operable if N is adjusted to the TSP within the calibration tolerance specified in the associated setpoint calculations since, as stated above, it is only the TSP (not the AV) that accounts for all the instrumentation errors, and N is so chosen that automatic protective action will correct the abnormal situation before a safetylimit is exceeded.
it is Mr. Burrows' view that the TS should focus on the TSP and not the AV. He indicate that the sole purpose of an Avis to use N as a limit for instrument uncertainties actually encountered during periodic testing. If actual test results exceed the AV, then the corresponding assumptions in the setpoint methodology must be revisited to ensure conu ed validity of the TSP selection. He indicated that his view is supported by ISA-867.04-1994.
PANEL REVIEW A. Panel Findinan on Mr. Burrows' Orlainal conce..Ta
- 1. The Panel considered Mr. Burrows' concem that plant TS that are based on the ISTS that include and designate AVs as LSSS, in lieu of TSPs, are inconsistent with requirements for LSSS as stated in 10 CFR 50.36. Furthermore, Regulatory Position 3 in the staft's draft Regulatory Guide DG-1054 (proposed Revision 3 to Regulatory Guide 1.105 on Instrument Setpoints for Safety-Related Systems) stating that AVs must be specified in the TS in order to meet 10 CFR 50.36, is similarfy inconsistent with those requirements.
11
5 As noted by Mr. Burrows,10 CFR 50.36 establishes the requirement for TS to include !
LSSS as stated under the section on Defined Terms above. The panel confirmed that the l
current ISTS allow either TSPs and AVs, or AVs alone, to be included in plant TS when ;
converting to the formst of the ISTS, and allow the Bases to describe either the TSP or 1
the AV as the LSSS. Thus, the issue,is whether these options satisfy the reguistory i requirement for an LSSS.
The Panel found this concem to be complex and its resolution required considerable discussion with members of the technical and legal staffs. The Panel found that both '
TSPs and AVs are important in determining instrument operability, in adddion, the i
I apprusch and treatment of TSPs and AVs have not been consistent in industry and regulatory guidance, since over time either one or both have been deemed to be the LSSS.
To better appreciate the relationship between the AV and the TSP, the Panel considered the typical process by which instruments are periodically tested. In this process a techrdclan determines the "as found" value of an instrument setting (protective device trip actuation point) and compares it to the TSP. If the "as found" value is not conservative s
with the TSP, the technician adjusts the protective 6vice to actuate at a value ("as left") !
that is consistent with the TSP. This provides the appropriate margins for instrument uncertainties, over the next surveillance interval, to ensuro that protective actions could be initiated in response to an abnormal situation such that safety limits would not be exceeded. In addition, if the setting had been found to be nonconservative with respect to the AV, additional actions should be taken by the licensee to assess the unexpected i response and consider its implication on operability. However, such follow up actions are l not imposed by any specific TS requirement.
I The Panel next considered whether 10 CFR 50.36 could be reasonably read to allow eitherTSP or AV to be the LSSS. If the regulation is read from the perspective that a
" setting"is the act of adjusting the instrumentation to a desired actuation point (i.e., the i
instrument is " set," resulting in a tiip setpoint " setting"), then this is consistent with the l
adjustment of the "as left" value noted above and would dictate that the TSP is the LSSS. l Altemately, if the regulation is read from the perspective that a " setting"is the actuation point of the instrumentation, then this is consistent with both the "as found" and "as left" values noted above and would allow either the TSP or the AV to be the 5.888. Therefore, 10 CI'R 50.36 could ressor. ably be read as allow.ag the use of either the .'SP or t. 'V as the LSSS.
The Panel explored the use of either TSP or AV as the LSSS in the ISTS and plant TS with senior members of the Offices of the General Counsel (OGC) and of Enforcemen (OE). It was the opinion expressed by the OGC and OE representatives that the value included in the ISTS table on trip system instrumentation (without consideration of informatiori contained in the Bases section) was the only TS value to which tne licensee could be held accountable for the adjustment ofinstrumentation settings. Its the Panel's conclusion, therefore, that if the TS table contains only the TSP, then a licensee must adjust the instrumentation consistent with this value, which is the "as left" value noted previously. However, if the TS table contains only the AV, then conceivably a licensee could adjust the instrumentation setting to that value, which is not consistent with the "as left" value noted previously and would not give the assurances that allinstrumentation uncertaintier. had been considered in establishing the setting used at the start of a l
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surveillance interval. (The Panel recognized that licensees whose TS include only AVs '
control protective device settings in accordance with plant procedures that are required to be maintained by TS and these procedures would require protective devices settings that are consistent with the TSP.) Accordingly, the Panel found that the 10 CFR 50.36 4
requirement for automatic protective action to correct an abnormal situation before a !
safety limit is exceeded would not be talisfied by reliance solely upon a plant TS table '
that contained only the AV.
Therefore, the Panel concluded that the LSSS is that setting for an automatic protective, device that is manualhr adjusted so that the device will initiate an automatic protective ;
action and that setting is the TSP. In contrast, the AV is not a setting used to adjust a protective device to initiate an automatic protective action. Rather, the AV is the limiting '
- ss found" value of an observed protective device setting that due to changes over time, primarily instrument dridt during the surveillance interval, v.ould not exceed the allowances for such uncertainties as used to establish the value of a TSP and, at the time it is observed, would satisfy the regulatory requirement for the LSSS. Therefore, the Panet agrees with Mr. Burrows that it is the TSP, not the AV, that satisfies the regulatory requirement for the LSSS. In addition, the Panel found that 10 CFR 50.36 does not ,
provides a sufficient regulatory basis for NRC to require AVs to be included in the ISTS or plant TS as stated in the staff's draft of Revision 3 to RG 1.105 (DG-1054).
- 2. i Ths' Panel considered Mr. Burrows' concem that the ISTS should focus left" value) not on the AVs. It is his opinion that an instrument channel can only be considered operable if it is adjusted to the TSP within the calibration tolerance specified in the associated setpoint calculations since it is only the TSP (not the AV) that accounts for all the instrumentation errors and it is so chosen that automatic protective action will correct the abnormal situation before a safety limit is exceeded.
As noted above, the Panel acknowledges the role that both the TSP and AV have played in the determination of instrumentation operability. However, the Panel found that only the TSP satisfies the requirements of 10 CFR 50.36 for the LSSS. Accordingly, the Panel agrees with Mr. Burrows that the ISTS and plant TS should include TSPs.
B. Panel Findinon on Mr. Burrows' Additional Sncems During Panel discussions with r. .. Bunows, four additional concems were brought forth. They are summarized, along with the Panel's findings, as follows:
3.
The Panel considered Mr. Burrows' concem that TS values should be stated as a valu with a i percent tolerance to provide a more precise setpoint. This format for TSPs is cummtly used for electrical system loss of voltage and undervoltage trip functions. Mr.
Bunows believes this TSP format should also be used in lieu of that currently used for instrumentation system trip functions that are values stated as a single sided bounding limit with s or 2 notation.
The Panel found that the use of single sided bounding limits for TSPs is consistent with rugulatory requirement for the LSSS and do not restrict the licensees' use of settings that are more conservative than the TS bounding limit. The Panel found that where TSPs were specified as a value with a i tolerance (double sided bounding limits), that the 13
Bases had not provided a rationale to exclude the use of a more conservative setting than allowed by the tolerance. The least conservative setting allowed by the tolerance would be equivalent to a TSP value when stated as a single sided bounding limit. The Panel could not identify a regulatory basis for imposing TSPs expressed as a
- tolerance.
Therefore, the Panel disagrees that TSPs should be stated as a value with a i tolerance in lieu of a single sided bounding limit'and recommends no staff action.
4.
The Panel considered Mr. Burrows' concem that Technical Branch (TB) preparation of Safety Evaluation Reports (SERs) that involve setpoint changes have been requested by NRR Project Managers (PMs) with unrea'istic due dates. Addiilonally, Mr. Burrows raised a concem about those instances where a PM drafts the SER and TB concurrence has been requested by the PM with an unrealistic due date, i
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l The Panel found that due dates should be discussed with and agreed upon by the TB before the start of work in accordance with NR.R Office Letter 803.
5.
The Panel considered Mr. Burrows' concems that there had been instances where Project Managers (PMs) had (1) reviewed and accepted licensees' amendment requests for TSP changes without seeking the review or concurrences of the TB with the primary responsibility for the review of the TSP being changed, or (2) requested reviews or concurrences by a TB that did not have the primary responsibility for the TSP being changed.
The Panel concluded that PM reviews of license amendments are Justified where the l has sufficient technical knowledge to perform an evaluation of TSP changes. The Panel l
notes that PM reviews have been a significant factor in reducing the backlog of open '
licensing actions. However, the Panoi also found that PMs should request concurrence i
from the appropriate TB to ensure that the evaluation is consistent with current practice. l 6.
The Panel considered Mr. Burrows' concem that there are NRC setpoint methodology documents for reviewers (specifically BTP PSB-1) that are inconsistent in the guidance provided for reviews of this area. '
The Panel found that the guidance in BTP PSB 1 which requires reviewers to confirm that
%th TSPs and AVs for the degraded voltage protection are in the TS under review is inconsistmt with tha ISTS that include only one or the other. As noted above, the Pan 's findings with respec. .o the 10 CFR 50.30 requirements for LSCS are not consistent witn the guidance contained in the staff's draft of RG 1.105. The Panelis unaware of any othar NRC setpoint methodology documents which provides guidance for reviews in this area.
C rs menton of Panet Dev= toned Concems The Panel identified four other related concems during its review that it considered and made recommendations as appropriate.
- 7. The Panel developed ~and considered the concem that the NRC needs to confirm that processes are in place to control changes to TSPs where only AVs are included in the TS.
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To date TS have been issued for 11 facilities based on conversion to the ISTS. All but two of these facilities (Ginna and Vogtle), have TS with only AVs. The Panel examined the staffs SERs for Clinton, Hatch Units 1 and 2, Peach Bottom Units 2 and 3, and San ;
Onofre Units 2 and 3 for TS amendments that proposed to relocate TSPs to licensee l
controlled documents. These SERs stated the staffs finding that adequate controls j (10 CFR 50.59) were in place for an/ subsequent licensee change to TSPs that would be relocated. Based on discussions with the Lead Reviewers for the remaining SERs for TS amendments that proposed to relocate TSPs to licensee controlled documents, it was confirmed that similar findings were made, in those SERs, with regard to the existence of l adequate controls for any subsequent changes to TSPs that would be relocated.
)
Inspections conducted by TSB for the Crystal River (the first TS conversion) verified that the TSPs were relocated to licensee controlled documents that are subject to the change controls of 10 CFR 50.5g. Subsequent inspections for TS conversions are being performed by Regional personnel using the guidance in the NRC Inspection Manual (Tl 2515/130, " improved Standard Technical Specification implementation Audits") that includes audits for verification of relocated requirements as follows:
- a. Verify that a sample of TS requirements listed as relocated in the licensee conversion submittal were relocated to the specified location.
- b. For those requirements sampled above that were relocated and subsequently modified, again relocated, or deleted, ensure, in accordance with Section 03.01.b.1, )
that the appropriate controls were used.
The Panel found that there are sufficient provisions within the NRC inspection program to confirm that processes are in place to adequately control changes to TSPs, in the interim, where only AVs are included in the TS. For the long term, the Panel's recommendations address restoring TSPs to TS consistent with the Panel's finding noted in item 1 above.
- 8. The Panel developed and considered the concem whether the NRC has adequate I assessment tools in place to verify that licensees are adequately determining l instrumentation setpoints. l Tha Panel found that the staff has the necessary regulatory tools (e.g.,10 CFR 50.54(f)
Leners and the ongoing Architect / Engineer Design Team inspections) to provide !
Information to assess licensee setpoint methodology and to ensure that appropriate findings are made on licensee practices in this area.
- 9. The Panel developed and considered the hypothetical question of what action the ISTS j would require if a licensee identified an "as found" setting that was less conservative than !
the TSP.
The Panel examined the ISTS for all four NSSS Vendors and found that the requirements i related to protective device settings are expressed in terms of requiring and l demonstrating operability and that speafic requirements are not set forth with regard to !
TSPs or AVs. Thus, one must rely on the guidance in the TS Bases on TSPs and AVs to i obtain the proper application of operability requirements for protective device settings. !
Based on the majority of the statements included in the ISTS Bases for Reactor Trip '
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I System instruments, the panel concluded that an "as found* setting that is less conservative than the TSP would be adjusted consistent with the TSP.
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The Panel held discussions with the manegement and staff of TSB and HlCB on how i licensees apply TS requirements for TSPs and AVs. Based on these discuss!ons there was agreement that AVs are consider 4d for operabliity determinations when surveillances
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are performed and that instrument channel settings are reset when they are found to '
exceed TSP values. There also was agreement inat TSPs are applied as a setting that an instrument channel must satisfy at the conclusion cf a surveillance.
l However, the Panel found that there is not consistency on how adjustments ofinstrument channel settings are to be made to assure that the TSP requirements are met. In RG 1.105 (Revision 2,1986), the " upper setpoint limit" as used in Figure 1 of the ISA Standard (See Enclosure 5) is stated to be the same as " trip setpolnts" as used in the .
STS, in that drift above the " trip setpoint"(in the STS) requires readjustment. However, the Bases for the ISTS for Babcock and Wdecx (S&W) Plants (NUREG-143 Westinghouse plants (NUREG-1431) include the following statement under a discussion of TSPs and AVs: i The Trip Setpoints are the nominal va!ues at which the bistables are set. Any histable is considered properly adjusted when the "as left* value is within the band for CHANNEL CAllBRATION accuracy (i.e., i rack calibration
+ comparator seMing accuracy). {
j The point in question is whether this statement modifies the TS requirements for TSPs that are stated as single sided bounding limits. For example, if a TSP is stated as s 1800 psig and the band for channel calibration accuracy is 20 psig, would an *as left* sotting of 1820 psig, or less but >1800 ps!g, satisfy the TS requirement of s 1800 psig. The HICS and TSB staff confirmed that an instrument channel setting of > 1800 psig would not sailsfy the TS requirement, even if the deviation from bounding TS limit was within the band for calibration accuracy as stated in the assodsted TS Bases.
In contrast, Westinghouse (W) stated their position on this matter in their December ig, I 1996, letter providing comments on Draft Regulatory Guide DG-1045 (RG 1.105 Rev.3).
Westinghouse indicated that TSPs are nominal values and that adjustment tolerances {
i about the specified value are appropeiste becau.e such uncertainties have been fa .ored into the setpoint analysis. Th 4, W indicates that the allowance noted in the Bases can be applied to the TS bounding lirrdts and that the Sasts for W plants TS have included auch statements since 1981.
The Panel's find;ng on this matter is consistent with the staffs position that the Bases ,
may not aber the TS requirements. However, the Panel concludes that some licensees l may apply the TS requirements for TSPs in a way that is consistent with the stated W position and as implied by the statements sneluded in the TS Bases. With respect to safety significance, the Panel concludes that the use of the snowance stated in the Bases when adjusting instrument settings should not create a safety concem when the allowance is property factored into the setpoint analysis. Nevertheless, the use of such allowances stated in the Bases of TS to deviate from TSPs stated in specnications are contraty to compliance with the TS requirements for bounding TSPs.
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The Panel also considered the application of fixed limits on TSPs in the manner used in Wstts Bar TS. The staff accepted TS that removed the indicators, i.e., tha s and a j
symbols, that bounded the values of specified TSPs that were renamed as " Nominal Trip {
' Setpoints." The intent appears to be to allow deviations from the specified TSPs using l the Bases statements on a channel being " property adjusted when the at left value is i
within the band for CHANNEL CAUBRATION accuracy
- The Panel finds this modification of the TSP requirements by statements la the Bases to be similar to the case above.
The Panel further considered the ISTS for the Diesel Generator- Loss of Voltage Start !
(NOREG 1432, "Standenf Technical Specifications - Combustion Engineering Plants) and i for the Emergency Diesel Generator Loss of Power Start (NUREG 1430, Standard i
Technical Specifications - Babcock & Wilcox Plants), that include surveillance i
requirements stating: " Perform CHANNEi. CALIBRATIONS with setpoint Allowable Value(s) as follows:" which rnight be misapplied to mean that the setting is to be adjusted to the risted AV, rather than the TSP that is not included in the ISTS.
in summary, the Panel found that there was a consensus based on staff experience that licensees would adjust an "as found" value that exceeds a TSP to a value consistent with the TSP. Nevertheless, the Panel found the statements in the ISTS and its Bases lack clanty and specificity with regard ic the relationship between operability and the use of TSPs and AVs.
- 10. The Panel developed and conaldered the hypothetical question of what action the ISTS would specify when a licensee identified an "as left" setting that was inadvertently lett less conservative than the TSP but was conservative with respect to the AV. ;
l The Panel found that a channel would be inoperable since its surveillance requirements 1 would not have been met since the 'as left' setting was less conservative than the TSP.
Action would have to bo taken to restore the channel to operable status by adjusting its setting to a value that is equal to or conservative with its TSP or other remedial ac6ons such as piscing the channelin trip would have to be taken as stated in the TS. The Panel also found that the required actions are independent of whether or not the "as left" value had exceeded its AV.
l Mgndino Procosal for Modificatkm of ISTS A proposal was submitted to the TSB on Apr# 11,19g7, by EELB to modify the ISTS for all NSSS vendors to require, among other things, both TSPs and AVs for the loss of voltage and degraded '
voltsge trip functions, an area of the EELB's primary review responsitdlity. A stated basis for this change was in comply with BTP PSB 1 which requires TS to include TSPs and AVs for voltage protection sensors and associated time delay devices. This proposed change would restore TSP to the ISTS.
The Panel did not attempt to evaluate the proposed change, but has stated its findmg that a regulatory basis does not exist in 10 CFR 50.36 for NRC to require TS to include AVs.
Nevertheless, the Panel recognizes the need for the staff to consider the proposed modifications of th'sISTS in light of the Panel's findings.
17
E. PanelRecommendations Breed on the preceding discussion, the Paners har the following recommandations.
1.
The Panel recommends that following appropriate stsff review of the Panel's findings, statV hold a public meeting with the NSSS Ownsts Groups to, (1) provide the NRC stMf poshhn that 10 CFR 50.36 requires the TSP to be the LSSB, (2) discuss the staff pcMan on the use of TS Bases to comply with TSP limHs, and (3) discuss the r:eed to revise the ISTS scacrdingly. '
2.
The Panel recommends that following the meeting with the 6ndustry, the staffinhiate actions necessary to update the ISTS in accord:ance with agency procedures (i.e., j 50.10g) for now staff positions to Ancorporste TSPs in the LCO Tables, consist <snt with th4 reqdrements for LSSS required by 10 CFR 50.36.
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- 3. l The Panel recommends that the staff meet with the licensees for the nine plants that !
have convented to the ISTS by relocating TSPs to licensee controlled documents to tiiscuss means to bring their TS into compliance with 10 CFR 50.33 as discussed in '
Recommendations 1 and 2 above.
4.
The Panel recommends that the staff ensure that TS Bases do not inappropriately suggest that protective devices could be adjusted beyond the TSP limito. The Panel recommends that the ataff provide guidance to licensees on compliance with TSP limits, )
I with emphasis on thosa situations where the TS Bases state that channels are considered operable when a TSP limit is exceeded by a tolerance that was treated as an instrument uncertainty in the establishment of the TSP. Because W has indicated (Se item 13 of Enclosure 3) that this practice was intended for W plants licensed since 19 this guidance is not restricted to plants that have converted to the ISTS with the Bases statement noted above. The Panel recommends that a generic communication should be !'
Assued to address the following:
- a. Guidance on adjusting setpoints to comply with the TS limits-b.
Guidance on TS changes for a licensee amendment request that could be submitted and that would incorporate a calibration tolerance or allowance for adjusting trip setpoints to s 'isfy the specified TSP limits. A suggested modelTS is provided to Enclosure 8 for the staffo consideration.
5.
The Panel recommends that the staff develop a plan providing the proper emphasis on TSPs in the ISTS Bases versus the cunent emphasis on the use of AVs for operability determinations.
6.
The Panel recommends that the staff assure consistency betweets the Panet's findings o TSPs and AVs and the next revision of RG 1.105. The Panel recommends th!
review documents for instmmentation setpoints, specificaHy BTP PSB-1, and to modify them as necessary to reflect the findings of the Panet {
i 7.
The Panel recommends that the technical staff in Headquarters and the Regions be infonned of the staffs actions on the Panal's findings as appropriate. ;
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8.
The Panel recommends that the stafI review procedures and guidance for PMs on handling licensing actions to ensune that clear guidance is provided for establishing due dates and identifying appropriate technical branches with review responsibility, ;
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Enclosurs 1 Memo, Burrows to Thaldier, dated March 17,1997 Differing Professional View Concerning Technical Specification Setpoints and Allowable Values forinstrumentation i
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1 Enclosure 2 Memo, SamuelJ. Collins, Director, NRR, dated March 24,1997 DlWoring Professional View (DPV) Panel 1
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l Enclosure 3 Documents Reviewed by Panel
- 1. Memo, Burrows to WormleVGrimes, dated 3/6/96 Westinghouse Standard TechnicalSpecifications - Requirements for Electrical / Instrumentation Control Systems
.2. Memo, WormleVGrimes to Bumms, dated 4/2/96 Technical Specification Requirements for instrumentation and Control Systems
- 3. Copy of 10 CFR 50.36 Technical Specifications
- 4. RG 1.105, Revision 2, February 1986 instrument Setpoints for Safety Related Systems
- 5. Memo, Burrows to WormleVGrimes, dated 8/9/96 Proposed Revision to Regulatory Guide 1.105, " Instrumentation Setpoints for Safety Systems" l
- 6. Memo, WormleVGrimes to Burrows, dated 8/29/96 Proposed Revision 3 to Regulatory Guide 1.105, " Instrument Setpoints for Safety Systems" i 7.
Copy of Draft Regulatory Guide DG-1045, Proposert Rev 3 to Regulatory Guide 1.105, October 1996 instrument Setpoints for Safety Systems
- 8. Copy of ISA SN' 04-1994 Setpoints for Nuclear Safety-Related instrumentation
- 9. Memo, burrows to Thatcher, dated 03/17/97 Differing Professional View Concomint Technical Specification Setpoints and Alle able Values forinstrumentation
- 10. ISA-867.04-1982 Setpoints for Nuclear Safety Related Instrumentation used in Nuclear Power Plants
- 11. Copy of Westinghouse Standardized Technical Specifications, Section 3.3, instrumentation and Bases 12.
Copies of Public Comments provided to the draft of Revision 3 to Regulator / Guide 1.105.
- a. January 9,1997, letter from Duke Power
- b. December 19,1996, letter from Westinghouse Electric Corporation
- c. December 23,1996, letter from Nebraska Public Power District
- d. March 4,1997, letter from Mr. W. Brown
- 13. Westinghouse letter to NRC dated December 19,1996 22
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. 1 Comments on Draft Regulatory Guide DG-1045 (RG 1.105 Rev 3)"Setpoints for i Safety Related Instrumentation" i
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Enclosure 4 Backoround on LSSS. Trio Setoolnts and Allowable Values This enclosure provides a historical summary of the requirements for Limiting Safety System Settings (LSSS), Trip Setpoints (TSPs), and Allowable Values (AVs). The first part addresses regulatory requirements as specified in the Code of Federal Regulations. The second part addresses requirements as specified in Standard Technical Specifications (STS) that are used as a model for the Technical Specifications (TS) of operating nuclear power plants. The third part addresses industry and NRC guidance on TSPs and AVs.
Part t Code of Federal Reauhuc.ns Federal Register, Volume 31, Number 158, Page 108g1 (31 FR 108g1)
On Tuesday, August 16, ig66, the Atomic Energy Commission proposed changes to $50.36,
" Technical Specifications" of Title 10, Part 50 of the Code of Federal Regulations (10 CFR 50.36 to add requirements for safety limits, maximum safety system settings, and minimum conditions for operation. The statement of consideration ncted that maximum safety system settings would be established at levels sufficlently low so that anticipated abnormal situations could be corrected without exceeding safety limits. The proposed wording for section (d)(1)(ii) was:
Maximum safety system settings are settings for automatic protective devices related to the variables on which safety limits have been placed pursuant to subdivision (l) of this subparagraph (1). A maximum safety system setting shall be so chosen that automatic protective action will correct the most severe abnormal situation anticipated before a safety limit is exceeded. if the automatic safety system does not function as required, the licensee shall take appropriate corrective action, notify the Commission, review the matter and record the results of the review and corrective action taken and the reasons therefor.
Federal Register, Volume 31, Number ig0, Page 12781 (31 FR 12781)
On Tuesday, Decorr.>er 17,19M, the Atomic Energy G nmissic,n finalized the alemakinc ': tion on TS by modifying the proposed changes to $50.36 by substituting the word " limiting" for the words " maximum" and " minimum"in describing safety system settings and conditions for operation, respectively. Other changes were made to the proposed $50.36 based on public comments. One change was to change the scope of variables from those "on which safety limits have been placed" to those "having significant safety functions." The appropriate corrective action for a system that does not funchon as required were modified by removing " corrective" to describe them and to note that they may include shutting down the reactor. The modified l requirements for section (c)(1)(ii) were stated as: l Limiting safety system settings are settings for automatic protective devices related to those variable having significant safety functions. Where a limiting safety system setting is specified for a variable on which a safety limit has been placed, the setting shall be so chosen that automatic protective action will correct the most severe abnormal situation anticipated before a safety limit is exceeded. If, during riperation, the automatic safety 24
l system does not function as required, the licensee shall take appropriate action, which i may include shutting down the reactor. He shall notify the Commission, review the matte and record the results of the review, including the basis for corrective measures taken.
of 1C .
n SS 0" 8 Federal Register, Volume 38, Number 84, Page 10815 (38 FR 10815) -
\
On Wednesday, May 2,1973, the Atomic Energy Commission issued proposed amendments
$50.36 to add provisions for TS for fuel reprocessing plants, that include a new section (c)(1)(ii)(8) on limiting control settings for fuel reprocessing plants. The limiting contro for fuel reprocessing plants are settings for automatic alarm or protective devices related to l those variables having significant safety functions. With this change, a number of minor edi '
and clarifying changes were included for $50.38. The requirements for limiting safety sy setting for nuclear reactors was renumbered as section (c)(1)(ii)(A). The requirements for i limiting safety system settings for nuclear reactors were modified by removing "most severe describe the abnormal situation anticipated for choosing a setting to correct before a s 4 is exceeded. Likewise, the corrective measures were expanded with the underlined cha follows: l He shall notify the Commission, review the matter and record the msults of the revi including the cause of the conditions and the basis for corrective AdQD taken to prec reoccurrence.
Federal Register, Volume 3g, Number 130, Page 24626 (3g FR 24626) on Friday, July 5,1974, the Atomic Energy Commission amended $50.36 to add requiremen for fuel reprocessing plants and editorial changes proposed in 38 FR 10815 as noted above.
Federal Register, Volume 53, Number 103, Page 1g240 ( 53 FR 1g240)
On Friday, May 27,1988, the Nuclear Regulatory Commission amended 550.36 as a part of incorporation of broad regulatory changes with mgard to records retention periods. Th to the requirements for limiting safety system sett'ngs t"bstituted "The licensee" for "He" in stating the requirement of ..nc.., shall notify the Commission and take corrective actions when a automatic safety system does not function as required.
Part 2 STS Guidance The early drafts of the STS for Westinghouse Plants, NUREG-0452, (circa 1974) had a section on LSSS under Chapter 2. " Safety Limits and LSSS." This. section specified that the Reactor Trip System (RTS) Instrumentation setpoints be set consistent with the TSP values shown in Table 2.2-1. Early drafts of the STS also included requirements for TSPs under Limiting Condibon for Operation (LCO) 3.3.2 for the Engineered Safety Features Actuation System (ESFAS) that were similar to those specified in the Chapter 2 section on LSSS for the RTS.
Administrative Controls in the earty versions of the STS, and in plant TS at that time, impose requirement for an abnormal occurrence report (later renamed as a licensee event report) 25
whenever an instrument channel was found to be inoperable. Consequently, a large number of Oports were required because normalinstrument drift caused setpoints to change during a surveillance interval such that the "as found" value pften exceeded the TSP when the next surveillance was performed. ]
\
Subsequent changes to the draft STS prop $ sed in the fall of 1975 added AVs to Table 2.2-1 for the RTS functions. The AV was determined by adding the channel uncertainty due to instrument l drtft to the TSP. Thus, a RTS channel would be capable of performing its safety function when , j the "as found" value of a protective device setting exceeded the TSP, so long as M did not ,
exceed the AV, i.e., instrument drift did not exceed the allowance for this uncertainty that was ;
used to determine the TSP. However, the instrument setting would be adjusted so that the "as j left" value did not exceed the TSP as specified by the LSSS specification for the RTS, or as l specified by the LCO for the ESFAS instrumentation. This action, adjusting the setpoint to not exceed the TSP, restores the margin for instrument drift that may occur over the next {
l surveillance interval.
When AVs were added to the STS, new actions specified the remedial measures to be taken when a setpoint exceeded the AV. The new actions were to (1) declare the channelinoperable and (2) apply the applicable action statement requirement of Spscific% 3.3.1.1 (the Limiting Condition for Operation for the RTS), until the channel is restored ic ' MRABLE status with its setpoint adjusted consistent with the TSP value. The latter action, adjusting the setting to restore the channel to operable status, would be taken as part of the surveillance that l
determined that the protective setting exceeded its AV. Hence, having restored the channel to operable status to complete the surveillance requirement, there would be no need to implement the new TS actions that were added to the STS. NUREG-0452 was finalized and issued in June l of 1978.
)
With tho' addition of AVs to plant TS, a basis was provided for a finding that a channel was operable when its setpoint was found to exceed the TSP but not the AV. This significantly reduced the number of abnormal occurrence reports that licensees had to submit when l instrument drift, which occurs during the surveillance interval, caused a setpoint to be found that exceeded its TSP. I Subsequent revisions of the Westinghouse STS, NUREG-0452, were issued up to and including Revisie- 4, dated Fall 1981, but without any significant change to the guidance on TSPs and AVs. In Jurae of 1987, the ,taff issued an updated version of the STS for Westinghouse (W) plants titled "W STS Desk Reference" to be used as necessary and appropriate to determine the difference between current licensing practice for W plants and that dommented in NUREG-0452, Rev. 4. What is significant about this version of the W STS is the manner in which AVs were treated. In addition, to the specification of TSPs and AVs for each trip function, three additional columns of data were added for the ReactorTrip System (RTS) and Engineered Safety Features Actuation System (ESFAS) instrumentation tables. One column was labeled as a " Total Allowance, (TA)," a second as " Sensor Error (S)," and the third was just identified as the letter "Z." The action requirements stated that with an RTS or ESFAS instrumentation or intedock setpoint less conservative than the AV shown in the table, adjust the setpoint consistent with the TSP value of thn table and determine within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> that a equation, relating the values of the three new ' ' ~ entries, TA, 8, and Z, and the "as measured" rack error for the affected channel, was satisfn if these requirements were not met, the attemative was to declare the channel inoperable and apply the applicable action statement requirement, for an inoperable channel, until the channelis restored to operable status with its setpoint adjusted consistent with the TSP.
26
f I
I In September 1992, the improved Standard Technical Specifications (ISTS) were issued as a series of NUREG documents (1430-1434) for each of the Nuclear Steam Supply System (NSS vendors. Changes were proposed by the vendor Owner's Groups and subsequently reviewed i and approved by the staff. Changes were made in the manner that setpoint requirements were specified. The section on LSSS for the RTS was removed and the setpoint table was moved to the LCO for the RTS. The LCOs for the RTS and ESFAS were changed to specify that the associated instrumentation shall be operable, but without the eariier reference to the adjustment of setpoints consistent with the TSP. j For NSSS vendors other than W, the tables for the RTS and ESFAS LCOs listed only the AVs '
and not the TSPs. For these non-W NSSS vendors, the ISTS Bases state that the Avis the LSSS.
The ISTS for Westinghouse plants include both the TSP and the AV, however a footnote for the TSP column of the LCO Table provides the option of a unit specific implementation to include only the AV. The associated Bases states that the TSP is the LSSS, but with the TSP in 3
brackets to indicate that it may be different on plant specific basis, i.e., it could be the AVif the '
TS Table used a single column format that did not include the TSP. The W ISTS dropped the three additional Reference," noted column above. factors that were added in the Staffs document titled "W STS Desk Part 3 Industrv and NRC Guidance j
in addition to the guidance provided in the early versions of the STS and subsequent ISTS, TSPs and AVs have been addressed in an industry standard that has been revised a number of times, j
and an NRC Regulatory Guide that was issued based on the original version of the industry a standard.
I initial Industrv Guidance The Instrument Society of America (ISA) issued a standard, ISA S67.04, "Setpoints for Nuclear Safety Related instrumentation Used in Nuclear Power Plants,"in 1982. The Preface to this ,
standard notes that setpoint drift is a problem which has led to numerous abnormal occurrence reports and that the ISA sponsored a review of the setpoint drift problem in April 1975 by {
establishing the committee that developed this standard. Figure 1 of the statuard (See Enclosure b) shows the relationshin between a safety ilmit (SL), the AV, and the TSP.1..a standard defined setpoint as: 4 A predetermined level at which a bistable device changes state to indicate thct the quantity under surveillance has reached the selected value.
The standard addresses the instrument uncertainties that are to be considered when establishing the AV to assure that it is chosen so that the SL will not be exceeded for anticipated operational occurrences and accidents. Since most instrument uncertainties are expressed as i values, that are normally distributed, it is very improbable that all uncertainths would ever occur at the stated value at the same time and in the non-conservative direction. An algebraic sum of the i
uncertainties would greatly over-estimate the uncertainly in obtaining a trip at the desired value of the monitored parameter (s). Hence, the standard endorses the use of the " square root of the sum of the squares" method for combining instrument uncertainties, to determine the value of an i
27 l
AV that is conservative with respect to the value of the measured parameter assumed by the safety analysis to initiate a protective action and that prevents a SL from being exceeded.
In addition, the standard requires that the TSP shall be a value which allows for drift and adjustment. Specifically, the standard requires that the TSP be chosen so that the corresponding AV is not exceeded due to (1) drift of that portion of the instrument channel which is tested when the setpoint is determined, and (2) actual setting of the setpoint within an alicwable tolerance of upper and lower setpoint limits about the TSP, also shown on Figure 1.
The ISA standard also addressed periodic testing by noting the following:
If the "as found" setpoint indicates the setpoint is within the "no readjustment" band (see Figure 1) or that calculations based on the analog value would result in setpoints within the "no readjustment" band, documentation of the results is the only required action. If the "as found" setpoint exceeds the upper setpoint limit, readjustment shall be performed to bring this channel back within the "no readjustment" band. If the "as found" setpoint is below the lower setpoint limit, readjustment may be made to avoid unnecessary trips, but is not mandatory.
Thus, while the standard defined a lower setpoint limit, it did not consider compliance with it to be a safety significant matter, nor one that it would be address by TS.
NRC Guidance NRC issued Regulatory Guide (RG) 1.105, " Instrument Setpoints for Safety-Related Systems,"
Revision 2 in February 1987 which endorsed the ISA Standard, ISA-S67,04-1982. The RG also discussed key terms used by the ISA standard that are not defined or have unclear application, and "for convenience" (sic), provided the following information:
The term " upper setpoint limit" as used in Figure 1 of the standard is the same as " trip setpoints" as used in aforementioned STS in that drift above the " upper setpoint limit" (standard) or " trip setpoint" (STS) requires readjustment.
With the clarification of the TSP as the uppei setpoint limit as stated in the RG, the difference ,
between the TSP t'nd the AV is reduced to just the l:.crument drift. Another clarification made by i the RG was:
The term " allowable value" as used in the standard is consistent with the usage in the bases sections of the STS (citation to NUREGs was provided)
The Bases for the Section 2.2, *LSSS," of the cited STS address the Reactor Trip System instrumentation Setpoints as follows:
l Operation with a trip set less conservative that its Trip Setpoint but within its specified !
Allowable Value'is acceptable on the basis that the difference between each Trip Setpoint and the Allowable Value is equal to or less than the drift allowance assumed for each trip )
in the safety analyses, i
The Panel notes the there are two precautions that should be taken when reading this statement. The first is that it doesn't say that the "as left" value of an instrument setting may be 28
i l
less conservative than the TSP. The LSSS requirement stated in the STS is that the reactor trip system instrumentation setpoints shal! be set consistent with the Trip Setpoint values shown in {
j Table 2.2-1 which are stated as a single side bounding limit, i.e, s or a than a stated value. '
Hence, this situation, where an instrument setting is less conservative than the TSP, requires an adjustment that would have to be made as a part of any surveillence procedure that determines the channel setting. <
The second precaution is with regard the stated basis for acceptable operation, "the differenca between each Trip setpoint and the Allowable Value is equal to orless than the drtft allowance assumed for each trip in the safety analysis." The approach stated in the ISA standard is to first determine an AV based on all uncertainties other than instrument drift (that ddft being for that portion of the instrument channel which is tested when the setpoint is detennined) and then determine the TSP such that the difference between the TSP and the AV is at least equal to the drift allowance assumed in the safety analysis, but surely not by using a value "less than" that as implied by the quoted basis. The quoted statement would only apply if the TSP is first deterrnined based on consideration of all instrument uncertainties including instrument ddft, and then the AVwas determined in a manner that satisfied the quoted basis. In this case, an AV would be conservative if the quoted clatement were true.
Subseouent Revisions of !ndustrv Guidangg !
(SA S67.041987, with a shortened title "Setpoints for Nuclear Safety Related instrumentation,"
was issued with the stamp "ANS/lSA-67.04-1988 Approved February 4,1988." The Preface c!
)
the standard stated: l The purpose of this revision is for clarification and to reflect current industry practice. The ,
term " Trip Setpoint"is now consistant with the terminology used in the NRC Standard l
Technical Specifications and reflects what was previously know as " Upper Setpoint Limit."
This version of the standard made a number of changes, only some of which are discussed here.
One change was to state that "each LSSS normally has two components, called a trip setpoint and its allowable value." In contrast, the Paners finding is that the LSSS 1.s the TSP, a value that is used to adjust a protective device to assure that is capable of performing its safety function. 1 The s:sndard addresses the topic " Safety Analysis" as follows: i The safety analysis establishes an analyticallimit in terms of a measured or calculated variable and a specific time after that value is reached to begin protective action.
Satisfying these two com traints will ensure that the safety limit will not be exceeded during anticipated operational occunsoces and design basis events. (The standard states that design limits for Engineered Safety Features are treated the same as safety limits.) Choosing a limiting safety setting (LSSS) to begin protective action before the analyticallimit is reached will ensure that the consequences of a design basis event are not more severe than the safety analysis predicted. An LSSS, derived from an analytical limit, is published in the technical specifications and maintained by plant operating procedures.
This discussion implies that the LSSS is the single value limit used to initiate a protective action, namely, the TSP.
29
This version of the standard defined the term "analyticallimit" as:
Umit of a measured or calculated variable established by the safety analysis to ensure that a safety limit is not exceeded.
The defined term "setpoint" as used in the prior version of the standard was change to " trip setpoint" and retained its prior definition as:
A predetermined level at which a bistable device changes state to indicate that the quantity under surveillance has reached the selected value."
Another change was to define the AV as:
The limiting value that the trip setpoint can have when tested periodically, beyond which the instrument channel is deciered inoperable and corrective action must be taken.
The Panel found that this appears to be an improvement to clarify the purpose of the allowable value.
The 1988 version of the standard stated the requirements for the trip setpoint as follows:
An allowance shall be provided between the trip setpoint and the analyticallimit to ensure a trip before the analytical limit is reached. The allowance used shall account for all applicable design basis events and the process instrument uncertainties listed below unless they were included in the determination of the analytical limit.
The Panel notes that this approach differs from the prior version of the standard that first determines an AV and, then based on that value, determines a TSP.
The requirements for the AV wers stated as:
The uncertainties of that portion of the instrument channel being tested to be used to determine the allowance between the trip setpoint and the Allowable Value are:
1
- 1. Instrument Calibration Uncertainties
- 2. ...strument Uncertaintios Dudng Normal Operation
- 3. Instrument Drift This change increases the difference between the AV and the TSP that one would calculate based on specification data for those uncertainties as compared to determinations of AVs based on the previous version of the Standard that only considered instrument drtft, since the consideration of the "no adjustment" band was effectively eliminated by the RG position that the
" upper setpoint" limit is equivalent to the TSP stated in TS.
The ISA Standard was subsequently revised and issued as ISA-S67.04, Part 1, Approved September 1994. This version of the ISA standard revised the definition of the AV to state:
30
S A limiting value that the trip setpoint may have when tested periodically, beyond which appropriate action shall be taken.
The Panel notes that " appropriate action'is broade'r in its implications but less definitive than previously stated as a being a condition that the instrument channel is declared inoperable.
However, with the 5 column format for setpoirh information in the Staffs Desk Reference version of the W STS, those TS requirements provide an option for a conclusion that a channel could be operable when the AV is exceeded if the equation using the other setpoint column data is satisfied. Hence, the AV is not always as a bounding limit for operability determinations. '
This version of the standard also defined the terms related to trip setpoints as determined durin surveillances as follows:
as found: The condition in which a channel, or portion of a channel, is found after a period of operation and before re-calibration (if necessary).
The Pat.W developed the view that this is the value of a measured parameter at which a protective device would initiate a safety action as determined during a surveillance test conducted after a period of time (the surveillance interval), but before any adjustment of the device setting has been made, as left: The condition in which a channel, or portion of a channel, is left after calibration or final setpoint device setpoint verification.
~
The Panel developed the view that this is the value of a measured parameter at which a protective device would initiate a safety action as determined during a periodic test, after any adjustment of the device setting has been made, when it is determined that such adjustment is necessary based on the "as found value."
The 1994 version of the standard also restored the "no adjustment" band about the TSP that was defined as a " region of calibration tolerance (acceptable as left condition)" on Figure 1 of the standard (See Enclosure 8). The Figure notation is that the calibration tolerance is addressed in Section 4.3.1 of the standard. The Panel assumes that the calibration tolerance is inclu
- nart of instrument calibration uncertainties attributed to the calibration method, item a) 3), but the Mandard uncertainty is not clear on where a calibration tolerance is olaced in othe defined li.e f instrum asiderations. The Puface to the standaro retained the clarification made in .a 1987 revision about the TSP being what was pr. viously know as the " upper setpoint limit" but did 1
not ad@ess the restoration of that term, " upper setpoint limit", in the cument (1994) version of the standard.
Part 2 of the ISA Standard, " Methodologies for the Determination of Setpoints for Nuclear Safety Related Inshumentation," was issued at the same time as Part 1. With regard to calibration tolerance, Part 2 of the standard implies that there are situations where a calibration tolerance may be used for and in lieu of the actual reference accuracy in the setpoint uncertainty i
calculation and without including the calibration tolerance as a separate te"m. Part 2 of the standard also provided three methods for determining TSPs and AVs based on the value of the {
Analytical Limit (AL) and instrument uncertainties. The first method determines both the TSP and AV using the AL and the uncertainties between it (the AL) and remaining two term, TSP and 1 AV. A second method determines the value of the TSP using the AL and all uncertainties between it (the AL) and the TSP, and thers subsequently using that TSP to determine the AV 31 l
l l
l based on the uncertainties between tt :t 9 i++ to ns. The third method is similar to the second, but first determines the AV based upon urau Jr., as between the AL and AV, and then uses that AV to determine the TSP based on the occur 63,/'s between it (the TSP) and the AV. Needless to say, the different methods will yield diffe" M iesults. Likewise, depending upon the method used, the treatment of the calibration tolerance as an uncertainty, including those cases where the standard would allow one to ignore the reference accuracy noted above, will yield yet different results with regards to the difference between TSPs and AVs.
i
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V p ,\
umrno swas g 1} NUCLEAR REGULATORY COMMISSION wAsNINGToN, D.C. 200064m
. March 17,1997 MEMORANDUM 70: Dale F. Thatcher Section Chief Advanced Designs,Section and Electrical components Electrien1 Engineering Branch Division of Engineering FROM:
Frederick H. Burrows, Electrical Eng Advanced Designs Section and er .
Electrical Components Eltetrical Engineering Branch Division of Engineering
SUBJECT:
DIFFERING. PROFESSIONAL VIEW CONCERNING TECHNICAL -
SPECIFICATION SETPOINTS AND ALLOWABLE VALUES FOR INSTRUMENTATION Attached is the subject Differing Professional View (DPV) which you should forward to our Office Director per the latest DPV policy guidelines.
Tom Dunning (TSB/NRR) and Virgil Beaston (EEL 8/NRR) are two qualified individuals who are willing to serve on the review panel for this DPV.
Attachment:
As stated e.
/
, b
. %q p *k* UNITED STATES s*
NUCLEAR REGULATORY COMMISSION WASHfMOTON, D.C. annan -
\ .... . '
DIFFERING pROFES510aAL VIEW CONCERNING TECNNICAL SPECIFICATION SETPOINTS AND ALLOWABLE VA FOR INSTRUNENTATION AY FREDERICK H._ BURROWS In a memorandum to J. Werniel and C. Grimes dated March 6,1996, I expressed a concern that the recent staff efforts to improve and simplify Westinghouse Standard Technical Specifications (STS have undermined efforts in the 1980s to produce a meaningful and technical c)oncise approach to satisfy 19 UR 50.36. Specifically, it is sty obieten that the use of an allowable value to detemine operability for an instrumentation channel in lieu of the channel's trip setpoint in technical specifications (TS) does not satisfy 10 CFR 50.36 and is not consistent with actual plant calculations that establish setpoints and with plant procedures that maintain the validity of those setpoints.
In a response of April 2,1996 C. Grimes and J. Wermiel stated that it was not clear if I had raised a par,ticular technical concern or policy concern regarding the appropriate means to reflect setpoint calculations and related maintenance practices into TS requirements. They also requested that I document sty concerns so that they could be addressed before a revision to Regulatory Guide 1.105, " Instrument Setpoints for Safety Systems," or further improvements to the STS were made.
Instead of writing a Differing Professional View to stay with the normal channels to express my con cerns(DPV) at that in the hopetime, that Ithose chose efforts and the inputs from others, such as Westinghouse, would convince the staff of'Accordir.31y, D.36. what I believeinis their failure Io produce STS that satisfy 10 CFR ,
me"randum to J. Werm1.1 and C. Grimes dated August 9,1956 I provided sty comments on the proposed Revision 3 to Regulatory Guide 1.105. In tha. meno I questioned whether the. staff was consistently applying 10 CFR 50.36 and stated that the staff was'downplaying the importance of the nominal trip setpoint, and that the nominal ; point is the only setting that will satisfy 10 CFR 50.36. In a response of ust,29, 1996 along.C.. Grimes and J. Wermini stated that sty comments would be consi with those obtained from the public.
red Now it appears that my comments and those by Westinghouse will'produc's vio change in the staff's approach to undermining the important of a channel's trip setpoint. Therefore, with this DPV, I wish to express my concerns as follows.
1.
Reguistory Position 3 in the staff's draft Regulatory hide DG-1045 (Proposed (circa October 1996) Revision 3 to Regulatory Guide 1.105) states:
The. allowable value, in conjunction with the trip setpoint, will detemine the limits on instrument ahTAfSDIN
, t -
1 operability and must be specified in the TS in order to meet 10 CFR 50.36. "The LSSS should be developed in accordance with the set standard, with the al;o. point methodology based on the
. le value listed in the TS and the relationship of the trip setpoint to the allowable value must be documented and controlled by the setpoint methodology.
10 CFR 50.36 states that TS will include limiting safety system settings (LSSS) and "where a limiting safety system setting is specified for a chosen that automatic protective action will correct th s situation before a safety limit is exceeded." !
methodology for instrumentation, it is only the trip setpoint whichIn a typ satisfies this requirement since its value accountsforalltheinstrumentationerrors.(gndnottheallowablevalue)
This is supported by l
ISA-567.04-1994 which states that " trip setpoints in nuclear safety-related instruments between the tri shall be selected to provide sufficient allowance i uncertainties."p setpoint and the safety limit'to account for Further, the standard states that 'an allowance shall be provided between the trip setpoint and the analytical limit to ensure a trip before the analytical limit is reached" and "the trip setpoint should be the value that the final setpoint device is set to actuate."
Therefore,' it is my view that the trip setpoint by itself should be considered the LSSS.
To use the allowable value as the LSSS or to include it as part of an LSSS (as the above quote from the draft only adds confusion to TS. revision to Regulatory Guide 1.105 does 2.
In the TSofforOperation Condition Westinghouse plants issued in the 1980s, a Limiting i t?>1cally state that an(LC0) for safety-related instrumentation would '
instrument channel was operable if its setpoint was .;et c1nsistent with values shown for the trip setpoints.
to this, the current Westinghouse STS states in the Bases that "if theContrary measured considered setpoint does not exceed the allowable value, the bistable is operab'.e."
It is any opinion that an instrument channel can only be considered operable if it is ad. justed to the trip setpoint within the calibration tolerance specified in the associated setpoint calculations since, as stated above, it is only the trip setpoint value (and not the allowable value) that accounts for all the instrumenta errors, and it is so chosen that automatic protective action will correct the abnormal situation before a safety limit is exceeded.
' ISA-567.04-1994 states that an allowable value may include instrument calibration uncertainties, instrument uncertainties during normal operation, and instrument drift associated with the portion of the instrument channel being tested.
It further states that the allowance for the trip setpoint shall account for all applicable design-basis events and process uncertainties (including those associated with the allowable value) unless they were included in the determination of the analytical limit.
- fr l l
From my viewpoint, the TS should fc:us on the trip setpoint value and not the allowable value. The sole purpose of an allowable value is to use it as a limit for instrument uncertainties actually encountered during periodic testing. If actual test results excaej the allowable value, then the '
corresponding assumptions in the setpoint methodology must be revisited to -
ensure continued validity of the trip setpoint selection. This is supported by ISA-367.04-1994, which states:
The purpose exceeded of the allowable value is to identify a value that, if the assum,ptions of the setpoint calculation.may mean that the instrum setpoint as-found condition exceeds the allowable value should beA chan evaluated for operabilit calculation methodology.y taking into account the setpoint In this quote, " operability" means future operability based on the revisited setpoint trip methodology setpoint value. assumptions and the setpoint set back to the specified l
l
y
/>#*%1 .
UNITED STATES s* U NUCLEAR REGULATORY COMMISSION WASHINoTON D.C. 3000Hept
..... March 24, 1997 MEMORANDUM T0: Roy P. Zimerman Associate Director for Projects ruce A. Soger, Director Division of Reactor Controls and Human Factors FRON: :h rector Office of Nuclear Reactor Regulation *
SUBJECT:
DIFFERING PROFESSIONAL VIEW (DPV) PANEL In accordance with NUREG/BR-0161 (attached), I hereby designate Roy Zimerman as the Chair of the ad-hoc DPV review panel and Bruce Boger as a panel member for the attached DPV. Management Directive and Handbook 10.159 are also attached.
The submitte'r of the DPV has provided a list of qualified individuals to serve on the panel, from which one member can be selected by the Panel Chair.
Please complete your review and provide your recomendation to me by May 9, 1997.
Attachments:
- 1. DPV
- 2. NUREG/8R-0161
- 3. Management Directive and Handbook 10.159 1
cc w/o attachments: '
, F. Burrows, DE l
Copyrighted Documents Addressed Under DPO For hard copy, refer to the PDR DPO
Subject:
Technik al .5pect kicdnasserromf s Ano Au.ou>ar ste. VoJue) Fe (t. INr1raum enveE ord l
l l
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