ML20217N614
| ML20217N614 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 04/30/1998 |
| From: | ENTERGY OPERATIONS, INC. |
| To: | |
| Shared Package | |
| ML20217N570 | List: |
| References | |
| NUDOCS 9805050385 | |
| Download: ML20217N614 (9) | |
Text
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t ATTACHMENT E
ICAN049802 PROPOSED TECHNICAL SPECIFICATION M
RESPECTIVE SAFETY ANALYSES IN THE MATTER OF AMENDING LICENSE NO. DPR-Si ENTERGY OPERATIONS. INC, 4
i ARKANSAS NUCLEAR ONE - UNIT ONE
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DOCKET NO. 50-313 i
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9805050385 900430 PDR ADOCK 05000313 P
' Attachment to
- ICAN049802 Page 1 cf 4 DESCRIPTION OF PROPOSED CHANGES The second paragraph in the Technical Specification (TS) 1.6.1 definition of quadrant power tilt (QPT) has been deleted. The deleted paragraph implied that the use of excore power.
range detectors is the preferred method for monitoring reactor core QPT. The proposed amendment aligns the ANO-1_QPT definition with that contair.ed in the improved Standard
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Technical Specifications for Babcock and Wilcox (B&W) plants, NUREG-1430, Revision 1, dated April,1995.
BACKGROUND Industry practice has been to emphasize the use of incore detectors as the preferred measurement source for determining QPT. This preference for using the incore' detectors is based upon the incore detectors having less uncertainty associated with their measured values.
Current ANO-1 procedures establish requirements for periodic monitoring of QPT with both the incore and excore power range detectors. These procedures are based upon a literal reading of the original TS definition and its implication that excore power range detectors are the preferred set of detectors for determining QPT. Until this proposed amendment is authorized, or until the improved Standard Technical Specifications - are implemented, monitoring both sets of detectors resolves any ambiguity regarding the preferred monitoring requirements.
1 DISCUSSION OF CHANGE The deleted paragraph in the TS 1.6.1 definition stated, in part, "... The average power is determined from an average of the outputs of the power range channels. If one of the power range channels is out of service, the remaining three operable power range channels or the incore detectors will be used to determine the average power..." The deleted paragraph, which implied that excore power range detectors are the preferred instruments for monitoring QPT, has not been revised since the original issuance of ANO-1 TSs on May 21,1974.
- ANO-1 Safety Analysis Report (SAR), Section 3A, Reload Report, Amendment 14, describes the relationship between the TSs and the Core Operating Limits Report (COLR). The SAR states that reactor power imbalance and QPT are monitored by three independent measurement systems. The primary incore detector system, the minimum incore detector system, and the excore power range nuclear instrument (NI) system comprise the three independent systems, in accordance with the following descriptions:
The primary QPT monitoring system is comprised of fixed incore detectors supplying signals to the on-line computer which processes the data through the nuclear applications software to calculate three-dimensional power distributions.
_ Attachment to ICAN049802 i
Page 2, of 4 The minimum incore detector system consists of a subset of the incore detectors that supply signals to an analog recorder without benefit of signal processing and signal-to-power conversion.
The NI system employs excore detectors to monitor neutron flux leakage from each e
quadrant of the core. Periodic heat balance calculations are perfonned to calibrate the instrumentation so that excore power. range detector currents are converted to core thermal power representation.
Normal operating limits for Cycle 14 are defined by the error-adjusted alarm setpoints shown in SAR Figures 3A-9 through 3A-17, Axial power shaping rod insertion limits and setpoints are specified in SAR Table 3A-11. QPT limits and setpoints are listed in SAR Table 3A-12.
Together, LCO 3.5.2, control rod group and power distribution limits, and LCO 3.5.4, incore instrumentation, along with operation within the COLR requirements assures compliance with the safety analysis. The following TSs are associated with this proposed change to the QPT
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definition:
e ' TS 3.5.2.4 establishes ANO-1 requirements for QPT. This specification refers to the COLR for the QPT limits. These limits in conjunction with the control rod position setpoints and operational imbalance setpoints in the COLR prevent power peaks that exceed the loss of coolant accident limits derived by Emergency Core Cooling Systems 1
. analysis and prevents departure from nucleate boiling during a loss of forced reactor coolant flow accident.
' The bases for LCO 3.5.2 state, in part, ",,. Actual operating limits depend on whether or not incore or excore detectors are used and their respective instrument and calibration errors. The method used to define the operation limits is defined in plant operating procedures."
LCO 3.5.4 applies to operability of the incore instrumentation system. This specification e
establishes limitations on the minimum number and arrangement for the incore detectors.
These specifications which apply nbove 80% power, as determined by the reactor coolant pump combination, affirm that incore detectors shall be operable for verification of power distribution limits (including QPT) and to' assist in the periodic calibration of excore detectors.
TS 6.12.3 establishes the administrative controls applicable to the COLR, identifies TS parameters requiring evaluation and inclusion in the COLR, references the B&W Topical Report, BAW-10179P-A, " Safety Criteria and Methodology for Acceptable Cycle Reload
- Analysis", which specify analytical methods used to determine the core operating limits, requires the core operating limits be determined so that all applicable limits of the safety analysis are met,' and describes revision requirements for the COLR.
' Attachment to ICAN049802 Page 3 of 4 The QPT limits and setpoints provided in the COLR are based on B&W topical BAW.
10122A, Revision 1, and B&W's letter to the NRC, Taylor to Norberg, dated April 21,1988, regarding " Extended Lifetime Incore Detector Error Allowances", both of which are referenced by BAW-10179P-A.- The references establish a method for the use of the full incore detector system or a subset of the full incore detector system for determining QPT.
NRC review and approval _of the B&W topicals provide evidence of the Staff's acceptance of the incore detector system for measuring QPT.
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The TS LCOs and their bases do not specify a preference for which detectors should be used to determine.QPT. A review of the design basis, SAR, and ANO-1 commitments conclude that a single source of data for determining QPT, i.e., the primary incore detector system, the -
i minimum incore detector system, or the NI excore detector system, satisfies the design and I
I licensing basis.
ANO-l's decision to implement'the improved-B&W STS definition of QPT provides a resolution of this issue. This proposed amendment to the TSs will eliminate any ambiguities associated with the original definition.' ANO has committed to conversion of the current TSs to the improved STS by letter 0CAN069502, dated June 21,1995.
DETERMINATION OF NO SIGNIFICANT HA7ARDS CONSIDERATION An evaluation of the proposed. change has been performed in ~ accordance with 10CFR50.91(a)(1) regarding no significant haards considerations using the standards in 10CFR50.92(c). A discussion of these stanouds as they relate to this amendment request
. follows:
Criterion 1 - Does Not Involve a Significant Increase in the Probability or Consequences of an Accident Previously Evaluated.
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i The proposed change to the quadrant power tilt (QPT) definition will not alter any Safety Analysis Report (SAR) assumptions established and implemented by the technical specifications. The proposed change will allow the use of either the incore detectors or the excore power range detectors for determining QPT. This change is consistent with the improved Standard Technical Specifications (STS) which has been previously approved by the NRC. QPT measured by incore detectors provides a more accurate indication of reactor core power distribution than the value determined from the excore detectors. The accident prevention and mitigation features of the plant are not affected by this proposed amendment.
Therefore, this change does Eg1 involve a significant increase in the probability or consequences of any accident previously evaluated.
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Attachment to ICAN049802 Page 4 of 4 l
Criterion 2 - Does Not Create the Possibility of a New or Different Kind of Accident from any Previously Evaluated.
The proposed change to the definition of QPT does not alter the ANO-1 SAR analysis or COLR. The change will clearly permit the use of either the incore detectors or the excore detectors for monitoring QPT. The design and physical configuration of the plant are not affected by this change.
Therefore, this change does E9.1 create the possibility of a new or different kind of accident from any previously evaluated.
Criterion 3 - Does Not Involve a Significant Reduction in the Margin of Safety.
The proposed change to the QPT definition incorporates the improved TS definition contained in NUREG-1430. The revised definition allows the use of either the incore detectors or the excore power range detectors for determination of QPT. The change does not vary or affect any of the plant's operating parameters. The COLR currently specifies acceptable QPT limits based upon the measurement techniques.
These limits are based upon the unique measurement characteristics of the incore and excore power range detectors and assure the measurement independent limit is not violated.
Therefore, this change does n91 involve a significant reduction in the margin of safety.
Therefore, based upon the reasoning prese...ed above and the previous discussion of the amendment request, Entergy Operations has determined that the requested change does n21 involve a significant hazards consideration.
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PROPOSED TECHNICAL SPECIFICATION CHANGES
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Inetrument Chennal Calibretion An instrument channel calibration is a test, and adjustment (if necessary), to establish-that the channel output responds with i
acce'ptable range and accuracy to known values of the parameter which the
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channel measures or an accurate simulation of these values.
Calibration shall encompass the entire channel, including equipment actuation, alarm or trip and shall be deemed to include the channel test.
1.5.5 Heat Balance Check A heat balance check is a comparison of the indicated neutron power and core thermal power.
1.5.6 Heat Balance Calibration An adjustment of the power range channel amplifiers output to agree with the core thermal power as determined by a weighted primary and secondary heat balance considering all heat losses.
Between 0 and 15% power, only i
the primary heat balance is considered.
From 15 to 100% power the heat f
balance is weighted linearly with only the. secondary heat balance being j
considered at 100% power.
1.6 POWER DISTRIBUTION 1.6.1 Quadrant Power Tilt j
Quadrant power tilt shall be defined by the following equation and is expresred as a percentage.
" *"Y
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100
-1 (Average power of all quadrants s
1.6.2 Reactor Power Imbalance Reactor power imbalance is the power in the top half of the core minus i
the power in the bottom half of the core expressed as a percentage of rated power.
Imbalance is monitored continuously by the RPS using input from the power range channels.
Imbalance limits are defined in Specification 2'1 and imbalance setpoints are defined in Specification
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2.3.
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l Amendment No. -1M, 4
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1 MARKUP OF CURRENT ANO-1 TECHNICAL SPECIFICATIONS (FORINFO ONLY) i i
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1.5.4 Instrument Chennel Celibration An instrument channel calibration is a test, and adjustment (if necqss ary), to-establish that the channel output responds with acceptable range and accuracy'to known values of the parameter which'the channel measures or an accurate simulation of these values. Calib:. ion shall encompass the entire channel, including equipment actuation, alarm l
or trip and shall be deemed tol include the channel test, l
I-l 1.5.5 Heat Balance Check A heat balance check is a comparison of the indicated neutron power and core thermal power.
l 1.5.6 Heat Balance Calibration An adjustment of the power range channel amplifiers output to agree with l
the core thermal power as determined by a weighted primary and secondary l
heat balance considering all heat losses.
Between 0 and 15% power, only l
.the primary' heat balance is considered.
From 15 to 100% power the heat balance is weighted linearly with only the secondary heat balance being considered at 100% power.
l 1.6 POWER DISTRIBUTION l
l 1.6.1 Quadrant Power Tilt l
I Quadrant power tilt shall beke defined by the following equation and is expressed as_A n percentage 1
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3 Power in any core quadrant 100
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(Average power of all quadrants s
Th: p;;;; in :ny qu;d::nt i; d;t:: in;d f ;; th: p: :: ::ng: h;nn:1 i
di pl:y:d :n th: ::n::1; f:: th:t q :d::nt. Th: v ::;: p: :: i:
determin:d f::= :n :v:::g: f th: cutput: cf.th: pr: ::ng: ch:nn:1:.
If ::: f th: p:x:: ::ng: ch:nnel; i: :;t :f :::vi :, th: ::scining th::: :p:::hl: p:x;; ::ng: :henn:1: :: th: in;;; detects:: uill h: used t: det;;;in: th :v:::; p:x::. The qued::nt p: :: tilt limit: :: :-
j functi:n f p;;; ::: :tsted ir Sp::ific ti:n 3.5.2.5.
I 1.6.2 Reactor Power Imbalance Reactor power imbalance is the power in the top half of the core minus the power in the bottom half of the core expressed as a percentage of rated power.
Imbalance is monitored continuously by the RPS using input from the power range channels.
Imbalance limits are defined in Specification 2.1 and imbalance setpoints are defined in Specification 2.3.
Amendment No, M-k, 4
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