ML20206Q426
| ML20206Q426 | |
| Person / Time | |
|---|---|
| Issue date: | 08/05/1998 |
| From: | Burrows F NRC (Affiliation Not Assigned) |
| To: | Callan L NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| Shared Package | |
| ML20206Q280 | List: |
| References | |
| NUDOCS 9905190127 | |
| Download: ML20206Q426 (9) | |
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j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20066 4 001
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MEMORANDUM TO: L. Joseph Callan, Executive Director for Operation Nuclear Regulatory Commission FROM: Frederick H. Burrows, Electrical Engineer ,
Electrical Engineering Branch , g Division of Engineering Office of Nuclear Reactor Regulation
SUBJECT:
REQUEST FOR REVIEW OF CONCERNS RELATED TO TECHNICAL SPECIFICATION SETPOINTS AND ALLOWABLE VALUES FOR INSTRUMENTATION UNDER FORMAL DIFFERING PROFESSIONAL OPINION (DPO) PROCEDURES in a memorandum dated March 17,1997, I expressed a Differing Professional View (DPV) concerning the use of allowable values to determine operability for safety-related I instrumentation channels in lieu of channel trip setpoints in technical specifications (TS).
Specifically, I expressed my view that the staff's practice of approving the removal of trip setpoints from technical specifications was deviating from the requirements of 10 CFR 50.36, " Technical Specifications." in an October 31,1997, memorandum, Samuel J. Collins, Director, NRR, provided me with the NRR Ad-Hoc Review Panel findings j and recommendations for my concerns. In a memorandum dated July 24,1998, Mr. Collins l has now stated that it is not an appropriate use of either NRC or industry resources to implement the DPV panel's recommendations. That is, Mr. Collins believes that allowable values, by themselves, satisfy the 10 CFR 50.36 requirement that the technical specifications include limiting safety system settings and that trip setpoints at not required.
Since the staff action discussed above concerns me and represents an unsatisfactory disposition of my DPV, I therefore now request that this issue be further reviewed under formal DPO procedures.
Much has been already written about the issues associated with the DPV. I am perplexed over the things that have been written. To spare myself from further frustration, I will not address all the shortcomings I see in the staff's responses to my concerns. Instead, I will try to support (in Attachment 1 hereto) my opinion by providing my view of the historical basis for requiring the trip setpoint and not the allowable value as the limiting safety system setting to satisfy 10 CFR 50.36. In doing this, l'will try to focus only on the words and actions associated with the original development of the term " limiting safety system setting" as contained in the AEC references used by the staff during the DPV process.
CONTACT: Frederick H. Burrows, EELB/DE/NRR 415-2901 9905190127 990513
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l L J. Callan 2 Additionally, I have expressed (in Attachment 2 hereto) some of my concerns over areas associated with the overall resolution of my DPV. Finally, I would like to recommend Mr. l Rick Tuley, Fellow Engineer, of Westinghouse Electr!c Company as a DPO par'l member should you so chose to accept my expression of a differing opinion as suitable for the formal NRC DPO process.
Attachtnents: As stated
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ATTACHMENT 1 VIEWS ON THE HISTORICAL BASIS FOR REQUIRING TRIP SETPOINTS LIMITING SAFETY SYSTEM SETTINGS Currently,10 CFR 50.36 (ii)(A) state's:
Limiting safety 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.
My opinion, stated briefly, is that an instrument channel's trip setpoint is the limiting safety system setting (LSSS) because:
- 1. The trip setpoint is the only setting to which an instrumentation technician adjusts the channel. It is the " leave alone" or "as-left" setting. An allowable value is not a setting, it is the measured "as-found" trip value for a given test of the channel's setpoint. Typical, there are no plant procedures requiring the channel to be set to the allowable value: plant procedures normally require the channel to be set at the trip setpoint within a small calibration tolerance.
- 2. The trip setpoint is the only setting that accounts for all the instrumentation uncertainties in associated setpoint methodology. Therefore, it is the only setting that is chosen (by the setpoint methodology) such that the automatic ;
protective action corrects the abnormal situation before a safety limit is !
exceeded. The allowable value does not account for uncertainties '
encountered during testing such as drift and calibration tolerances.
Therefore, a channel with an "as left" setting at the allowable value will not correct (within the probability assumption of the setpoint methodology) the abnormal situation because it does not account for errors such as drift.
To establish my views on the historical basis for the trip setpoint as the LSSS that satisfies the above quote from 10 CFR 50.36, I reviewed the Atomic Energy Commission (AEC) documents (referenced by Geary Mizuno (OGC) in his March 16,1998, memo to file and listed at the end of this attachment under references) which addressed proposed amendments to 10 CFR 50 pertaining to Technical Specifications. Specifically, the AEC l stated in Appendix "B" to Reference 1 (which proposed a revision to 10 CFR 50.36) that- l l
Technical specifications will include items in the following categories: ;
l (ii) Maximum safety system settings are settings for automatic protective devices related to the variables on which safety limits have been placed pursuant to subdivision (i) of this subparagraph (1). A ]
maximum safety system setting shall be so chosen that automatic i
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protective action will correct the most severe abnormal situation anticipated before a safety limit is exceeded.
Also in a note serving as'a cover letter to Reference 1, the Director of Regulation for the AEC stated that the attached, proposed revisions to 10 CFR 50.36 would accommodate the previous ACRS suggestions pertaining to trip settings for safety systems by adding safety limits and maximum safety system settings.10 CFR 50.36 was further revised in accordance with Reference 2. Specifically, safety system settings with significant safety ,
functions were also required and in Appendix "A" of Reference 2 " limiting" was to be I substituted for " maximum" t.nd " minimum"in describing safety system settings. A quick comparison of these proposed revisions to 10 CFR 50.36 and the current version shows no i difference as far as relating to my proposed differing opinion.
In Appendix "D" to Reference 2; the AEC staff discusses the content of technical specifications. Specifically, in the Section IV entitled " Development of Technical Specifications," the development of technical specifications encompassing limiting safety system settings is discussed. included was a figure (see the left portion of Figure 1 included herein) which illustrated the concept of limits such as the LSSS. As can be seen from Figure 1, the LSSS was selected "on the safe side of the safety limit" and:
The region between this setting and the safety limit should be sufficient to e!!ow for corrective action by the safety (protection) system to return tha situation to normal or to shut the reactor down before the safety limit would be reached for the most severe abncrmal situation anticipated during the life of the plant. This means that circuit response times and transient characteristics, including overshoot, must be taken fully into account. Also, included must be an allowance for calibration uncertainties and instrument inaccuracies, in Appendix "D" immediately following the above quote is the statement "The licensee is free to operate with any safety system setting within the limiting value. Now he statement appears difficult to understand because how can you have any setting within one value without a specified range unless your setting is the value itself? Therein lies the problem which is the heert of my differing opinion.
Appendix "D" goes on to say:
On the safe side of the limiting safety system setting lies the zone of normal operations. Allowance must be made for the possibility that the value of the variable may transgress the normal zone occasionally due to instrument drift, minor operational errors and normal fluctuations in process or control characteristics.
Therefore, a margin should be left between the normal operating zone and the safety system setting because of these factors.
j Appendix "D" also listed specific examples of technical specifications that had been developed under the system discussed therein. Among the plant-specific technical specifications listed were those for San Onofre Generating Station, Unit 1. These were also l included in Reference 2 as Appendix "G." In Section 2.1 of SONGS 1 Technical !
Specifications, there was included a table entitled " Maximum Safety Systerr. Settings" l
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3 which listed " maximum safety system trip settings" for several parameters such as pressurizer pressure: high. The value listed (also depicted in Figure 1) was s 2220 psig.
The associated discussion goes on to say, "Tpe maximum settings of the pressurizer high level trip and the pressurizer high pressure trip are established to maintain the DNB ratio . . . I
" Further, Section 6.1 states that "When Maximum Safety Setting is viola.ted, the incident will be reviewed and acted upon . . . "
The above discussion represents the historical basis for the inclusion and description of LSSS's in technical specifications. About 13 years after the AEC referenced documents were issued, I joined the NRC as an instrumentation and controls reviewer. One of the first issues i struggled with was the s and a contained in limiting safety system setting in technical specifications because sometimes they were listed as a minimum value for a high !
level trip instead of a maximum value for example. Also I realized that there had to be some j limiting setting to keep from encroaching too far into the normal range. As a result, for the !
last 17 years I have been a proponent of a setpoint with a i calibration tolerance as the !
limiting safety system setting (shown on Figure 1). It should be noted that the DPV panel disagreed with this format for an LSSS in their report dated October 31,1998, although my position appears to me to be consistent with the intended LSSS of 10 CFR 50.36 and any confusion could have been easily remedied in the technical specifications.
For completeness, I have added graphically to Figure 1 the staff's position which is attempting to establish the allowable value as an LSSS. I disagree with those staff and I industry efforts and believe they are not consistent with an LSSS originally included in j technical specifications as required by 10 CFR 50.36. As I noted above Appendix "D" '
stated that "The licensee is free to operate with any safety system setting within the limiting value." I take this to mean (based on the SONGS 1 Technical Specifications) that ;
any value more conservative than the LSSS is acceptable as a final channel "as-left" setting j which the allowable value does not satisfy. I also believe the staff has been remiss in not following appropriate proposed rulemaking procedures since it appears they are revising 10 i CFR 50.36 by now establishing a new, less conservative LSSS. Ultimately, the judgement should be based on an understanding of the quotes from the two AEC references and a study of Figure 1 herein.
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REFERENCES
- 1. Atomic Energy Commission, AEC-R 2/50, " Proposed Amendments to 10 CFR 50:
Technical Specifications; Technical information Required of Applicants," dated j June 30,1966. .
- 2. Atomic Energy Commission, AEC-R 2/67, " Amendments to 10 CFR 50 - Technical Specifications; Technical information Required of Applicants," dated October 16, 1968.
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l ATTACHMENT 2 CONCERNS PERTAINING TO THE RESOLUTION Of THE DPV REGARDING SETPOINTS AND ALLOWABLE VALUES
- 1. First, it is my opinion that the'DPV panel did an outstanding job in documenting the history of setpoints, allowable values, and limiting safety system settings (LSSS) as contained in 10 CFR 50.36.. This effort was further supported by a March 16,1998, note to file written by Geary S. Mizuno (OGC). Samuel Col! ins in the July 24,1998, DPV disposition memorandum and the staff in the June .22,1998, DPV follow-up action memo have chosen to set this information aside and act against the DPV panel )
recommendations, the OGC " written posit!on," and my written view. The basis for i the staff's action is "the regulations are not clear in this area, and that precedence on how the regulations have been implemented support the view that the AV satisfies the requirement that the TS include the LSSS."
I do not agree that the regulations are not clear in this area. My review of the documents associated with original AEC/ACRS efforts for establishing limiting safety system settings in 10 CFR 50.36 and technical specifications indicate to me that they '
dealt solely with trip setpoints. Allowable values were never mentioned and, in fact, were not even developed as a concept until years later. What is obvious to me is that allowable values were developed as a joint venture with industry to encompass issues such as drift, operability, and reportability-not to serve as an LSSS. Although the 1 technical specifications were changed and the associated industry standard and I regulatory guides have been revised to emphasize allowable values, I am not aware of any effort to change 10 CFR 50.36 to encompass allowable values as the LSSS. I believe items can be added to the standard technical specifications without being required by 10 CFR 50.36. But should the things that have been added now be used-to interpret what was originally intend 1d as an LSES? I think notl Shouldn't the staff i have changed 10 CFR 50.36 first before going down a new road with industry where original staff intentions and interpretations have now been changed via revised industry standards, regulatory guides, and standard technical specifications? I think l sol Instead of admitting our mistakes associated with standard technical '
specifications, we are admitting that our regulations are unclear and that they do not readily encompass the actions we have already taken. l
, 2. The DPV panel and the staff have agreed that removing trip setpoints from technical specifications is not a safety issue. I do not agree. :I have stated repeatedly that technical specifications without trip setpoints included as the limiting safety system i settings do not meet the requirements of 10 CFR 50.36. Is compliance /non-compliance with 10 CFR 50.36 a safety issue? As can be seen from review of the Figure 1 in Attachment 1, the allowable value is closer to the safety limit than the trip setpoint. Is this reduction in " safety margin" related to an LSSS a safety issue? The staff's fundamental basis for there not being a safety issue is reliance on plant procedures to control trip setpoints. Is there a safety issue when plant procedures and not technical specifications control setpoints (the most critical adjustment in an instrument channel)? Technical specifications give the impression that it is acceptable i
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2 to remain at the allowable value and not adjust the channel to its setpoint following periodic surveillance because in some cases the standard technical specification bases are vague and misleading in the area of instrument channel operability and the role of the allowable value. Is this a safety issul? ,
- 3. Samuel Collins memorandum of October 31,1997, requested the staff to review and provide a response to eight DPV panel recommendations. The June 22,1998, staff response is silent on several of those as is Samuel Collins' DPV disposition memo dated July 24,1998.
- 4. In an October 31,1998, memorandum Samuel Collins requested the staff to provide the actions proposed to address the DPV panel's recommendations and a schedule. In .
a June 22,1998, memo the staff stated it was inappropriate to implement the panel's recommendations. Mr. Collins agreed with the staff's determination in his July 24, 1998 memo. Per NRC Directive 10.159, " Differing Professional Management Provisions,"it is an objective of the NRC DPV/DPO policy "to ensure the full consideration and prompt disposition of DPVs and DPOs by affording en independent, impartial review by qualified personnel." As noted in my previous May 21,1998, memo to you, I expressed my belief that Mr. Collins actions were not prompt. Now I would like to add that I believe his dispositioning of my DPV appears not to reflex an independent and impartial review. That is, while it is true that the DPV panel performed a nonconfrontational, impartial review of the issues I raised, Samuel Collins did not in that he involved individuals in his decision-making process who have directly participated in the staff position which I disagreed with in my DPV. In other words, the staff had two chances to present their argument - once to the DPV panel and once to Mr. Collins - while I had but one (except for a brief meeting I had with Mr. Collins to complain about the DPV process and some participation in discussions with OGC).
Also it should be noted that one of the individuals who signed the staff's June 22 memo was a member of the DPV panel and that the June 22 memo was not dispatched until Mr. Collins' July 24 decision was final thereby eliminating any chance for a rebuttal from me.
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