ML20058B535
| ML20058B535 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Catawba, McGuire  |
| Issue date: | 11/18/1993 |
| From: | Mcmeekin T DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20058B539 | List: |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 GL-82-33, NUDOCS 9312020112 | |
| Download: ML20058B535 (10) | |
Text
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Dar he Company T C Afamn McGwre Nuclear Generation Department Vice President 12~00 Hagers Terry Road (A!GOIA)
(704)S75-4800 Huntersnile, NC 28078-8M5 (704)873-4809 Dx DUKEPOWER November 18, 1993 U.S. Nuclear Regulatory Commissi.
Attention:
Document Control Desk Washington, D.C.
20555
Subject:
McGuire Nuclear Station, Units 1 and 2 Docket Nos.:
50-369 and 50-370 Deletion of the Boronometer as a Method for Meeting a Regulatory Guide 1.97 Commitment
Reference:
Letter Duke Power to NRC, October 23, 1990 Same Subject for Catawba Nuclear Station Docket Nos:
50-413 and 50-414 Letter NRC to Duke Power, May 16, 1991 NRC Accepted Catawba's Proposal to Delete Latonometer Gentlemen:
On December 17, 1982. Generic Letter 82-33 (Supplement I ta EUREG-0737) was issued by tl e NRC.
This letter included additional clarif2 cation regarding Regulatory Guide 1.97, Revision 2.
. Duke Power Company responded to the
]
Regulatory Guide 1.97 portion of the Generic Letter on March. 29, 1984.
Additional information was submitted on April 14, 1986 concerning exceptions to and deviations from the regulatory guide. In a letter (SER) to Duke Power dated March 23, 1987, the NRC concluded that Duke had provided an explicit commitment on conformance to Regulatory Guide 1.97, and that Duke had either conformed to or was justified in deviating from the regulatory guide with three exceptions.
The three exceptions were the Accumulator Tank level and pressure, Containment Sump water t emperature, and Steam Generator level.
One of the regulatory guide variables that pertains to PWRs is "RCS Soluble Boron Concentration".
This Type B variable is intended to provide post-accident l
inf ormation to indicate whether the plant safety function of reactivity control is being accomplished.
McGuire's commitment relative to this variable was to utilize the installed Boronometer which had a different range than that required.
l 9312O20112 931118 l
l PDR ADOCK 05000369 p
PDR t
Abo 3 Il q
t U.S. Nuclear Regulatory Commission November 18, 1993 Page 2 by the regulatory gui d e',
but was considered adequate. for. the - anticipate'd concentrations of boron.
Sampling and analysis were stated to be the backup source of information on the reactor coolant soluble boron concentration.
McGuire' Nuclear Station is planning on permanently removing the boronometers on -
both Units from service..The Station is currently utilizing the Post-Accident Sampling System capability for sampling und analysis of the reactor coolant system to satisfy the regulatory guide.- recommendatien for - verifying boron concentration.
Additionally, daily sampling of the reactor coolant system is currently being performed.
Daily sampling of the reactor coolant system has proven to be the most reliable method for obtaining boron concentration at McGuire.
Sampling and chemical analyses is also considered as the most desirable method for the station to meet the Regulatory Guide 1.97 recommendations. The attached document provides_the basis for changing this commitment. An evaluation has been performed to assess.
the affect on plant safety if the boronometers were permanently removed from
service, and there la no adverse impact on nuclear safety associated with such a deletion.
This was the expected conclusion'since the NRC has accepted that sampling and laboratory analysis satisfy. the intended monitoring function for this variable at other nuclear stations (including Catawba Nuclear Station).
I believe that the deletion of the boronometer and implementation of daily sampling is not a change to Duke's intent of meeting _ the regulatory guide recommendations. Only the manner in how the station accomplishes verification of soluble boron concentration is being altered.
Therefore. _ I believe this particular commitment change falls under the purview of 30 CFR 50.59.
This letter provides you detailed information of this intended change.
Very truly yours, fC4/7//
T.C. McMeekin PTV/boronmtr Attachments
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I U.S. Nuclear Regulatory Commission November 18, 1993 i
Page 3 I
xc:
Mr. S.D. Ebneter Regional Administrator - Region II U.S. Nuclear Regulatory Commission 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 l
Mr. V. Nerses Office of Nuclear Reactor Regulations l
U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 9H3 Washington, D.C.
20555 Mr. G. Mexwell Senior Resident inspector l
McGuire Nuclear Station l
l Mr. Dayne Brown Chief Division of Radiation Protection j
P.O. Box 27687 Raleigh. NC 27611-7687 l
l l
l' I
f
U.S. Nuclear Regulatory Commission November 18, 1993 Page 4 bxc:
M.S. Tuckman G.D. Gilbert R.O. Sharpe
.R.E.. Hall
~
E.M. Geddie l
B.H. Hamilton M.K. Nazar R.B..Travis (MG01CP)
T.D. Curtis (MGOISE)
K.D. Thomas (MG02EE)
L.S. Reed (MG02EE) q A.V. Carr.(PB05B)
W.M. Sample (EC05N)-
i Z.L.. Taylor (CN01RC) l M.E. Patrick (ONO3RC) l M.E. Pacetti (MG02ME)
H.E. Vanpelt (MG02ME)
R.T. DeMuro (MC02EE) i T.A. Belk (MG01CP) i File: 801.01 RG 1.97 Topical s
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t I
j McGuire Nuclear Station j
l Revision Of Regulatory Guide 1.97 Commitment Monitoring Reactor Coolant System Soluble Boron Concentrations j
McGuire Nuclear Station is planning to permanently take the boronometers on Units i
1 and 2 out of service. The boronometer is described'in Table 1-6 of the FSAR.
I This table provides a listing of the Regulatory Guide 1.97, Revision 2 variables
.l and McGuire's conformance or exception to them.
On page 13 of this table
(
(Attachment I), the boronometer is described as the installed instrumentation l
used to monitor reactor coolant soluble boron concentration.
Sampling and j
analysis is stated to be the backup source of information on this variable. The i
j following paragraphs discuss the basis behind the station's decision to utilize j
l sampling and analysis as the primary. source of informationt for meeting the l
regulatory guide recommendation. Attachment II is the proposed FSAR Table 1-6 revision as it will appear in the 1994 update.of the FSAR.
l j
Background
l The boronometers at McGuire experienced numerous problems during the initial start-up of the Units. These problems resulted in a relatively poor calibration accuracy on the equipment as well as the need for frequent calibrations.
The l
boronometer became a high maintenance item as a result. 'During this startup period, daily sampling of the reactor coolant system was initiated as an interim -
j compensatory measure for monitoring soluble boron concentration. The station has reviewed the status of the boronometers and concluded that.the modifications and l
maintenance necessary for the existing boronometers to provide a reliable l
indication is not cost effective.
It has also been concluded that the boronometer is not the optimum choice for meeting the Regulatory Guide 1.97 I
recommendations.
Criteria For Selection of-RG 1.97 Type A, B, and C Variables As stated in Duke Power's response to NUREG-0737, Supplement 1, the Station Emergency Procedures and the Safety Psrameter Display System (SPDS) Critical i
Safety Functions were key factors to be considered when the Regulatory Guide 1.97 variables were selected. The Emergency Procedures provided the primary guidance for selection of the Type A variables. The SPDS Critical Safety Function (CSF)
Status Trees formed the basis for selection of the Type B and C variables.
For the "Subcriticality" Critical Safety Function, McGuire's -SPDS monitors neutron flux and Control Rod position to ensure the CSF is satisfied.
The Regulatory Guide 1.97, Rev. 2 guidance identifies neutron flux as the key Type B variable to monitor, with Control Rod Position as a secondary variable.
Reactor coolant soluble boron concentration is not an SPDS variable at McGuire.
The primary reason the boronometer is not suitable as an input to the'SPDS is that during an accident (ESF actuation) the normal letdown lines from the reactor coolant system automatically isolate. The boronometer monitors the coolant in the letdown line and so it too becomes isolated from the reactor coolant system.
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I Because the boronometer is not referenced in any Emergency Procedure or Abnormal Operating Procedure and is not utilized as an input to the SPDS, it dues not' meet Duke Power's criteria as a Type A, B, or C Regulatory. Guide 1.97 variable.
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Assessment of Plant Conditions During and Following an Accident As discussed above, the boronometer is isolated from the reactor coolant system at the onset of an accident when the Engineered Safety Features actuate.
The i
boronometer is, therefore, incompatible with the intent of Regulatory Guide 1.97 which addresses accident and post-accident requirements. However, the use of the
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Post-Accident Sampling System ~ to obtain a sample of primary coolant and j
subsequent chemical analyses is the appropriate method to determine soluble boron j
concentration during and following an accident.
i The McGuire Post-Accident Sampling System meets all the criteria of Item. II.B.3
(
in NUREG-0737 and has been found acceptable by the NRC (NUREG-0442, Supplement l
- 6. dated February 1983).
Recommended Range l
The range of concentrations that laboratory analysis can determine reactor coolant soluble boron concentration is better than that associated with the l
boronometer. Regulatory Guide 1.97 recommends a range of.0 to 6000 PPM for this variable.
The McGuire boronometer has a total range of 0 - 5000 PPM and, i
therefore, deviated from the regulatory guide. The NRC Staff stated in the SER (letter NRC to Duke, March 23, 1987) that this deviation went beyond the scope of the RG 1.97 conformance review and would be addressed as part of the NRC's review of NUREG-0737, Item II.B.3, Post-Accident Sampling System.
The NRC l
concluded that the McGuire Post-Accident Sampling System met all the criteria of Item II.B.3 in NUREG-0737 and was found acceptable by the NRC (NUREG-0422 j
l Supplement 6, dated February 1983). The Post Accident Sampling System at McGuire as described in the FSAR and the NRC SER does not utilize ' the boronometer.
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However, the method of sampling and analyses for boron. was found to be satisfactory. The range of concentrations over which the laboratory analysis can
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be performed is 0 - 8000 PPM.
1 Accuracy of Indication As discussed below, the accuracy of laboratory analyses to determine reactor coolant soluble boron concentration is better than that associated with the boronometer, therefore, it meets the Regulatory Guide 1.97 recommendation.
The boronometer calibration method consists of mixing various concentrations from 0 to 2000 PPM boron in 200 PPM increments in an' external mixing tank.
These concentrations are then circulated through the boronometer vessel. The neutron source generates neutrons that are attenuated by the varying boron concentrations. The reduction in neutron counts as detected by the boronometer's four detectors are correlated to the proper boron concentration. This is done by a microprocessor that repeatedly solves a mathematical equation which relates neutron pulse rate, sample temperature, and PPM boron in the sample solution. i l
s
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Samples of the various boron calibration concentrations are also taken from the external mixing tank and analyzed through chemical analysis to determine the true boron concentration. The chemically analyzed " standard" is then compared to the boronometer indication for calibration purposes.
Because the boronometer.
instrument error and the chemical analyses inaccuracies must be combined to i
determine the total error tolerance during calibration, the resulting tolerance for the boronometer indication is greater than that associated with sampling i
alone.
Safety Evaluation Summary
}
A safety evaluation was. performed by McGuire. Mechanical / Nuclear Engineering Section to assess the impact on plant safety if the boronometers are removed from
't l
service.
This document is included as Attachment III.
The safety evaluation
[
concluded that there is no adverse safety impact associated with not using the l
boronometers.
l Conclusion l
i Sampling and analysis of the reactor coolant system to monitor soluble boron concentration is the optimum method for meeting this Regulator Guide 1.97 recommendation for McGuire Nuclear Station.
The existing boronometers are not designed to perform this post-accident function, nor do they have the range and j
accuracy associated with sampling and chemical analyses.
The boronometer I
indication is not referenced or required for the'. performance of any plant l
Emergency and Abnormal Operating Procedure and it does not serve as an input to t
l the Safety Parameter Display System. Therefore, it does not meet the Station's criteria as a Type A, B, or C RG 1.97 variable.
l The boronometer performs no control or protective functions, and it is not used as a basis for fundamental operating decisions. The safety evaluation determined i
that there is no adverse impact to nuclear safety associated with the non-use of this system.
Based upon the capabilities of other plant syr,tems and administrative programs, and the lack of any unreviewed safety questions, the boronometers may be deleted.
The Regulatory Guide 1.97 recommendation of monitoring reactor coolant soluble boron concentration may be satisfied by sampling and chemical analysis.
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I ATTACllMENT I McGuire Nuclear Station Appendix 1. Chapter 1 Tables and Figures i
Table 1-6 (Page 13 of 69). Regulatory Guide 1.97, Rev. 2 Review i
B-3 Variable:
RCS Soluble Boron Concentration Range:
0 to 6000 ppm j
i RG 1.97 3
)
Recommended Catego ry:
1 DPC Category:
3 l
Existing Design:
This instrumentation has dual indication with ranges of 0 to 2500 ppm and 0 to 5000 ppm.
I 1
Compliance:
The range is not in total compliance with the recommendations of RG 1.97, Rev. 2.
Display:
Dual Range on a Control Room recorder.
l Position:
The range of the installed instrumentation is adequate for anticipated concentrations of boron, with sampling and analysis available to provide i
backup information.
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I (01 MAY 1992) i
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ATTACIIMENT II McGuire Nuclear Station Appendix 1. Chapter 1 Tables and Figures i
Table 1-6 (Page 13 of 69). Regulatory Guide 1.97, Rev. 2 Review B-3 Variable:
RCS Soluble Boron Concentration Range:
0 to 6000 ppm RG 1.97 3
Recommended Category:
DPC Category:
3 Existing Design:
This variable is monitored by sampling and l
laboratory analysis.
Sampling frequency is determined by plant conditions and operating j
procedures.
I Compliance:
This instrumentation is in compliance with Duke's interpretation of Regulatory Guide 1.97, Revision 2 as clarified by Letter Duke Power to NRC, November 18, 1993.
Display:
Not Applicable Position:
Evaluation of available equipment and the use of sampling and laboratory analysis has been determined to be adequate for the intended function.
(PCOPOSED 1994 UPDATE)
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ATTACIIMENT III McGuire Nuclear Station Units I and 2 Safety Evaluation Non-use of the Boron Concentration Measurement System (Boronometer) l