ML20035G021
| ML20035G021 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 04/13/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20035G018 | List: |
| References | |
| NUDOCS 9304260034 | |
| Download: ML20035G021 (9) | |
Text
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NUCLEAR REGULATORY COMMISSION s
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WASHINGTON, D. C. 20555 V.T /
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 53 TO FACILITY OPERATING LICENSE NO. NPF-37, AMENDMENT NO. 53 TO FACILITY OPERATING LICENSE NO. NPF-66, AMENDMENT NO. 42 TO FACILITY OPERATING LICENSE NO. NPF-72, AND AMENDMENT NO. 42 TO FACILITY OPERATING LICENSE NO. NPF-77 COMMONWEALTH EDIS0N COMPANY BYRON STATION. UNIT NOS. 1 AND 2 BRAIDWOOD STATION. UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-454. STN 50-455. STN 50-456 AND STN 50-457 1
1.0 INTRODUCTION
In a letter dated April 15, 1992, as supplemented November 23, 1992, Commonwealth Edison Company (CECO, the licensee) proposed changes to the Technical Specifications (TS) for both Byron and Braidwood Stations, Units 1 and 2.
The proposed TS changes are the result of a setpoint reconciliation pro 9 ram initiated by CECO for the Byron and Braidwood stations. The specifics of the setpoint study were previously presented to the NRC by Ceco at their Chicago, Illinois office on April 30, 1991, and again on August 6, 1991, where program results were presented and a follow-up action plan was proposed. The setpoint reconciliation program resulted in proposed revisions to TS Section 2.2-1, Table 2.2-1, TS Section 3.3.2, Table 3.3-4 and the associated Bases.
The licensee stated that 25 setpoints were to be evaluated in the setpoint study. The November 23, 1992, submittal provided additional clarifying information that did not change the initial proposed no significant hazards consideration determination.
2.0 BACKGROUND
in November 1990, Westinghouse issued a revision of the Byron /Braidwood setpoint bases (error analysis) document.
Commonwealth Edison Company engineering noted inconsistencies with the Measurement and Test Equipment accuracy (MTE) and other setpoint error assumptions incorporated by Westinghouse.
Commonwealth Edison Company engineering evaluated the revised Westinghouse bases document and determined that some values listed in the Byron /Braidwood TS could be affected (Total Allowance, 2, Sensor Error, Trip Setpoint, and Allowable Value).
Subsequent meetings were held with the NRC where CECO committed to an evaluation of the Westinghouse assumptions and revised bases document to confirm the continued Westinghouse setpoint bases applicability to Byron /Braidwood stations.
9304260034 930413 DR ADDCK 05000454 PDR
- 3.0 EVALUATION The Byron /Braidwood TS Section 2.2.1, Table 2.2-1, TS Section 3.3-2 and Table 3.3-4 are of the five column type listing values for Total Allowance (TA), Z, Sensor Error (SE), Trip Setpoint, and Allowable Value (AV). The inclusion of values of Z, SE and TA provide a means within the Westinghouse setpoint methodology to determine channel operability should the "as measured" rack or sensor allowances exceed the TS allowable value (trigger value).
The initial setpoint values for the reactor trip system (RTS) were developed by i
Westinghouse and the Engineered Safety Features Actuation System (ESFAS) values were determined by Sargent and Lundy/ Westinghouse.
The licensee found inconsistencies with the assumptions used by Westinghouse l
in the setpoint bases document. Among these discrepancies were the error terms for MTE ratio that considered better accuracy than actual plant measurement and test equipment being used fcr calibration.
In addition the as-built condition (instrument type, options) did not always agree with the Westinghouse assumptions. The licensee confirmed that 25 setpoints were evaluated in the setpoint study. Of these setpoints, 10 initially resulted in zero or negative margin with respect to the safety analysis (CSA+ Margin was inadequate). By improving the accuracy of the error terms and calibration process the licensee was able to demonstrate positive margins for 8 of the 10 i
setpoints.
The two remaining setpoints, Steam Generator Level Hi-Hi (Model D4) and reactor coolant system (RCS) Low Flow required re-evaluation of thc safety analysis by Westinghouse to include the revised Byron /Braidwood plant specific error terms.
The results obtained by Westinghouse showed that there was sufficient analytical margin to allow a revision to the safety analysis limit without affecting the result of the safety analysis.
Commonwealth Edison Company engineering concluded that a TS revision to Tables 2.2-1 and 3.3-4 for TA, Z, SE, and Allowable value were required.
Based on the results of the setpoint study the revised values for TA, SE, and Z, in many cases, would no longer satisfy the TS equation 2.2-1, Z+RE+SEsTA.
Equation 2.2-1 provides a licensee a method to determine instrumentation operability when the "as measured" rack drift exceeds the allowable value and provides a threshold value for reportable events. The equation is no longer satisfied based in part on the licensee's decision to use an available or developed margin to maintain instrument setpoints by revising the allowable values. The Westinghouse methodology states that with reduced margin, the use of SE in Table 2.2-1 will result in the sum of Z+RE+5E being greater than TA.
The licensee has, therefore, proposed that the values for SE, RE and TA be removed from the TS. The TS 2.2-1 equation Z+RE+SEsTA will also be deleted.
The deletion of values for Z, SE, and TA from the TS limits a licensee's flexibility in responding to instrumentation channels found outside the allowable value.
However, an allowable value is acceptable in determining instrumentation operability and is based on industry standards and practice.
The licensee states the calibration tolerance controls the setpoint within procedures and is the normal basis for determining when to recalibrate and confirm instrument operability. The licensees setpoint methodology is based on the methodology developed by Westinghouse and presented in WCAP-12583,
" Westinghouse Setpoint Methodology for Protection Systems, May 1990." The resulting three column TS format is acceptable to the staff.
{
An additional change requested by the licensee is a revision to Functional Unit 16.a, Turbine Trip, Emergency Trip Header Pressure.
The proposed change is the result of an installation of a new pressure switch designed for higher i
fluid pressure and not a direct result of the Ceco setpoint study. The resulting trip setpoint and allowable value are greater than the values currently specified in the TS. The setpoint calculations for this functional unit were not part of the CECO setpoint study but were developed by Sargent and Lt.ndy. The licensee stated that the revised setpoint will result in a anticipatory reactor trip earlier than that provided by the present setpoint.
r This is acceptable to the staff.
The licensee's proposed TS amendment requires equipment changes ano revised test equipment requirements be implemented prior to adopting the Ceco setpoint i
study results. The setpoint MTE ssumptions require the use of new measurement and test equipment.
The installation of temperature compensation transmitters is also assumed by the study.
In addition, more stringent calibration tolerances are required for some bistables.
The above calibration and equipment modifications are intended to ensure that the revised setpoint study reflects plant as-built and calibration procedures / practices.
4.0 PROPOSED Ceco SETPOINT STUDY TS CHANGES 4.1 BYRON UNITS 1 AND 2 2.2 LIMITING SAFETY SYSTEM SETTINGS REACTOR TRIP SYSTEM INSTRUMENTATION SETPOINTS 1.
TS 2.2.1, ACTION b.1 is deleted and ACTION b.2 is merged with ACTION b.
2.
Equation 2.2-1 is deleted along with definitions for Z, RE, SE, and TA.
TABLE 2.2-1 REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS 1.
The columns for Total Allowance (TA), Z, and Sensor Error (SE) have been deleted for all Functional Units of Table 2.2-1.
2.
The Allowable Values for the following Functional Units have been revised as a result of the CECO setpoint study:
2.
Power Range, Neutron flux a.
High Setpoint l
b.
Low Setpoint 5.
Intermediate Range, Neutron Flux 6.
Source Range, Neutron Flux
l 9.
Pressurizer Pressure - Low 10.
Pressurizer Pressure - High 11.
Pressurizer Water Level - High 12.
Reactor Coolant Flow - Low 13.
Steam Generator Water Level Low - Low b.
Unit 2 t
14.
Undervoltage - Reactor Coolant Pumps i
15.
Underfrequency - Reactor Coolant Pumps 16.
Turbine Trip a.
Emergency Trip Header Pressure 3.
The setpoint for Functional Unit 16.a Table 2.2-1, Turbine Trip, Emergency Trip Header Pressure was revised to reflect a new-instrument installation.
4.
Note 1, Parts (i), (ii), and (iii) have been revised to delete information specific to previous fuel cycles.
5.
Table 2.2-1, Note 2; revised the value that the maximum trip setpoint should not exceed the computed trip setpoint value.
6.
Table 2 2-1, Note 4; revised the value that.the maximum trip setpoint should not exceed the computed setpoint value.
7.
Note 5 has been deleted. The values for sensor errors are no longer applicable. '
BASES
' 2.2-1 REACTOR TRIP SYSTEM INSTRUMENTATION SETPOINTS The optional provision to determine the operability of a channel when the trip setpoint is found to exceed the allowable value has been deleted.
INSTRUMENTATION 3/4.3.2 ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUMENTATION LIMITING CONDITION FOR-0PERATION 1.
TS 3.3.2, ACTION b.1 is' deleted and ACTION b.2 is merged with Action b.
2.
Equation 2.2-1 is deleted along with definitions for Z, RE, SE, and TA.-
I
z.
...z
= = -
e i
- i TABLE 3.3-4 ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUMENTATION SETPOINTS 1.
The columns for Total Allowance (TA), Z, and Sensor Error (SE) have been deleted for all Functional Units of Table 3.3-4.
i 2.
The Allowable Value has been revised based on the Ceco setpoint study results for the following functional units:
1.
Safety Injection c.
Containment Pressure - High-1 d.
Pressurizer Pressure - Low (Above P-II) e.
Steam Line Pressure - Low (Above P-ll) 2.
L c.
Containment Pressure - High-3 3.
Containment Isolation b.3 Containment Pressure - High-3 4.
Steam Line Isolation c.
Containment Pressure - High-2 d.
Steam Line Pressure - Low (Above P-11) e.
Steam Line. Pressure Negative Rate-High (Below P-11) 5.
Turbine Trip and Feedwater Isolation b.
Steam Generator Water Level !;igh-High (P-14) 1)
Unit 1 6.
Steam Generator Water Level - Low-Low-Start Motor-Driven Pump and Diesel-Driven Pump 2)
Unit 2 4
d.
Undervoltage-RCP Bus-Start Motor-Driven Pump and Diesel-Driven-7 Pump 9.
Engineered Safety Feature Actuation System Interlocks Low-Low T,y, P-12 c.
=
=
= =.
- .=.
,a I '
3/4.3 INSTRUMENTATION BASES 3/4.3.1 AND 3/4.3.2 REACTOR TRIP SYSTEM and ENGINEERED SAFETY-FEATURES ACTUATION SYSTEM INSTRUMENTATION i
The optional provision to determine the operability of a channel when the trip setpoint is found to exceed the allowable value has been deleted.
4.2 BRAIDWOOD UNITS 1 AND 2 2.2 LIMITING SAFETY SYSTEM SETTINGS REACTOR TRIP SYSTEM INSTRUMENTATION SETPOINTS 1.
TS 2.2.1, ACTION b.1 is deleted and ACTION b.2 is merged with ACTION b.
2.
Equation 2.2-1 is deleted along with definitions for Z, RE, SE, and TA.
TABLE 2.2-1 REACTOR TRIP SYSTEM INSTRUMENTATION TRIP SETPOINTS 1.
The columns for Total Allowance (TA), Z, and Sensor Error (SE) have been deleted for all Functional Units of Table 2.2-1.
2.
Note 1, Parts (i), (ii), and (iii) have been revisedLto delete information specific to previous fuel cycles.
3.
Note 5 has been deleted. The values for sensor errors are no longer applicable.
I 4.
The Allowable Values for the following functional units have been revised as a result of the CECO setpoint study:
2.
Power Range, Neutron flux a.
High Setpoint b.
Low Setpoint 5.
Intermediate Range, Neutron Flux 6.
Source Range, Neutron Flux 9.
Pressurizer Pressure - Low 10.
Pressurizer Pressure - High 11.
Pressurizer Water Level - High 12.
Reactor Coolant flow - Low L
13.
Steam Generator Water Level Low - Low b.
Unit 2
t t.
F I
i l 14.
Undervoltage - Reactor Coolant Pumps 15.
Underfrequency - Reactor Coolant Pumps 16.
Turbine Trip a.
Emergency Trip Header Pressure l
5.
Table 2.2-1, Note 2; revised the value that the maximum trip 'setpoint' should not exceed the computed trip setpoint.
6.
Table 2.2-1, Note 4; revised the value that the maximum trip setpoint i
should not exceed the computed setpoint.
7.
The setpoint for Eunctional Unit 16a, Table 2.2-1, Turbine Trip, Emergency Trip Header Pressure was revised to reflect a new instrument installation.
BASES 2.2-1 REACTOR TRIP SYSTEM INSTRUMENTATION SETPOINTS I
The optional provision to determine the operability of a channel when the trip setpoint is found to exceed the allowable value has been deleted.
INSTRUMENTATION i
3/4.3.2 ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUMENTATION LIMITING CONDITION FOR OPERATION 1.
-TS 3.3.2, ACTION b.1 is deleted and ACTION b.2 is merged with Action b.
2.
Equation 2.2-1 is deleted along with definitions for Z, RE, SE, and TA.
3.
Removed footnote *. Applicable to Cycle 1 only.
TABLE 3.3-4 ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUMENTATION TRIP SETPOINTS 1.
The columns for Total Allowance (TA), Z, and Sensor Error (SE) have been deleted for all Functional Units of Table 3.3-4.
2.
The Allowable Value has been revised based on the Ceco setpoint study results for the following functional units:
i 1.
Safety Injection c.
Containment Pressure - High-1 d.
Pressurizer Pressure - Low (Above P-11) e.
. Steam Line Pressure - Low (Above P-li) j 2.
Containment Pressure - High-3
=
-. = ~.
a.
-g tv p
! t l
l 3.
Containment Isolation b.3 Containment Pressure - High-3 l
4.
Steam Line Isolation l
?
c.
Containment Pressure - High-2 d.
Steam Line Pressure - Low (Above P-ll) e.
Steam Line Pressure Negative Rate-High (Below P-ll) l 5.
Turbine Trip and Feedwater Isolation b.
Steam Generator Water Level High-High (P-14)
I
- 1) Unit I e
- 2) Unit 2 6.
{
t I
c.
Steam Generator Water Level-Low-Low-Start Motor-Driven Pump and Diesel-Driven Pump l
- 2) Unit 2 l
d.
Undervoltage-RCP Bus-Start Motor-Driven Pump and Diesel-Driven Pump l
9.
Engineered Safety Feature Actuation System Interlocks l
c.
Low-Low T,,,
P-12 3/4.3 INSTRUMENTATION BASES 3/4.3.1 AND 3/4.3.2 REACTOR TRIP SYSTEM and ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUMENTATION The optional provision to determine the operability of a channel when the trip setpoint is found to exceed the allowable value has been deleted.
5.0
SUMMARY
l Based on the above evaluation, the staff finds the proposed changes to the; Byron and Braidwood TS to be acceptable. The revised allowable values and setpoints were developed using an accepted setpoint methodology. The CECO setpoint study _ incorporates plant specific error terms and assumptions and is, therefore, representative of plant as-built conditions and surveillance requirements. - However, the Ceco setpoint study results and resultant'TS revisions are dependent on the licensee's use of new test and measurement l
equipment, temperature compensation transmitters, and revised calibration-procedures. The licensee's decision to revise the Byron'and Braidwood TS to a P
. o-.-
o
_g_
three column format and delete the values of TA, SE and Z from Tables 2.2-1 and 3.3-4 based on the CECO setpoint study results, is also acceptable to the staff.
6.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of the amendments.
The State official had no comments.
7.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (57 FR 24666). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). ' Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
8.0 CONCLUSION
The Commission has concluded, based on the considerations discussed.above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such-activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: C. Doutt Date: April 13, 1993 L_