2CAN099805, Application for Amend to License NPF-6,modifying Notes in Table Associated with Tech Specs 2.2.1,3.3.1.1 & 3.3.2.1 Re Operating Bypass Setpoint

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Application for Amend to License NPF-6,modifying Notes in Table Associated with Tech Specs 2.2.1,3.3.1.1 & 3.3.2.1 Re Operating Bypass Setpoint
ML20153D844
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 09/17/1998
From: Hutchinson C
ENTERGY OPERATIONS, INC.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20153D847 List:
References
2CAN099805, 2CAN99805, NUDOCS 9809250207
Download: ML20153D844 (13)
v • d • e


Text

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8.

Entzrgy oporttions, Inc.

, =Entergy 1448 Sft 333

==

C. Randy Hutchinson Vcc Preson Oreraf(ns AND September 17,1998 2CAN099805 U. S. Nuclear Regulatory Commission Document Control Desk j

l Mail Station OPI-17 Washington, DC 20555 '

Subject:

Arkansas Nuclear One - Unit 2 Docket No. 50-368 i License No. NPF-6

' l Technical Specification Change Request Modifying the 10*/. Operating Bypass 1 Setpoint Gentlemen:

l Attached for your review and approval are proposed changes to the Arkansas Nuclear One l Unit 2 (ANO-2) Technical Specifications. The proposed changes modify the notes in the l

, tables associated with Specifications 2.2.1,3.3.1.1, and 3.3.2.1. By letter dated September 4, l 1998, (2CAN099801) ANO-2 reported a plant condition where the automatic removal of the

! operating bypass for the high logarithmic power trip function was not within the required

! value listed in the technical specifications. The report stated that a technical specification

( change request would be submitted to establish setpoint requirements consistent with the plant design.  !

l This letter requests the associated technical specification changes consistent with the plant design and the ANO-2 safety analyses. This amendment request also contains some additional  ;

! administrative changes needed to clarify the requirements associated with all the required l l operating bypasses. i The proposed change has been evaluated ir . ecordance with 10 CFR 50.91(a)(1) using criteria in 10 CFR 50.92(c) and it has been determined that this change involves no significant hazards considerations. The bases for these determinations are included in the attached

! submittal. l i i Entergy Operations requests that the effective date for this change be upon issuance. This request is neither exigent nor emergency because the plant is currently operating in Mode 1, 30 0

however, if a plant shutdown were to occur, this change would be necessary to facilitate P

, startup. Therefore, your prompt review is requested.

i 9909250207 980917 I PDR ADOCK 05000368 P PDR.

  • U. S. NRC September 17,1998 2CAN099805 Page 2 Very truly your , ,k -

e CRH/rde Attachments To the best of my knowledge and belief, the statements contained in this submittal are true.

SUBSCRIBED AND SWORN TO before me, a Nota Public in and for A

County and the State of Arkansas, this /~7 day of - . At. _, /m 2 1998.

/

~

g ,,

w 'O#iCIAL SEALi~~El Notary kublic Andrea Pierce 4 Notary Public, State of Arkansas h My Commission Expires /M/NIJod7 l County of Pope j

/ LMy Cannyss!o_n Exp.12/15/2007_ f cc: Mr. Ellb W. Merschoff l Regional Administrator U. S. Nuclear Regulatory Commission Region IV l

611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 l

NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box 310 London, AR 72847 Mr. William D. Reckley NRR Project Manager Region IV/ANO-1 & 2 U. S. Nuclear Regulatory Commission NRR Mail Stop 13-H-3 One White Flint North 11555 Rockville Pike Rockville, MD 20852 l Mr. David D. Snellings Director, Division of Radiation Control and Emergency Management Arkansas Department of Health 4815 West Markham Street j Little Rock, AR 72205

/

l i

, ATTACHMENT I

2CAN099805 PROPOSED TECHNICAL SPECIFICATION ABT,Q RESPECTIVE SAFETY ANALYSES IN THE MATTER OF AMENDING LICENSE NO. NPF-6 ENTERGY OPERATIONS. INC.

ARKANSAS NUCLEAR ONE. UNIT TWO DOCKET NO. 50-368

  • l
  • Attachment to 2CAN099805 Page 1 of10 DESCRIPTION OF PROPOSED CHANGES The following changes have been proposed to the Arkansas Nuclear One - Unit 2 (ANO-2)

Technical Specifications (TS).

l e TS Table 2.2-1 notes (1), (2), and (5) have been modified by minor wording changes to clarify the notations. In addition, the power level at which the core protection I calculators (CPCs) may be bypassed and where automatic removal of the bypass is l required in notation (5) was changed from 10*A to 102% power.

. The bases for specification 2.2.1 was also modified by the addition of a sentence  ;

indicating that the operating bypasses are discussed in the bases section for TS 3.3.1.1 I and 3.3.2.1. Additional clarifying information about Table 2.2-1 notation (1) was also added to the Logarithmic Power Level- High section of this bases to make it consistent

! with the associated table notation.

e TS Table 3.3-1 notes (a), (b), and (c) have been modified by minor wording changes to i clarify the notations. In addition, the power level at which the CPCs may be bypassed i and where automatic removal of the bypass is required in note (c) was changed from l 10*A to 10% power.

l

, e TS Table 3.3-3 note (a) was modified by minor wording changes to clarify the notation.

I

. TS Table 3.3-4 note (1) was modified by minor wording changes to clarify the notation.

. The limiting condition for operation (LCO) section of TS 3.10.3 has been modified to l include the allowance to suspend the noted requirements of Table 2.2-1 during the l performance of the special test exception.

e The bases section for specifications 3.3.1.1 and 3.3.2.1 was modified by the addition of l clarifying information regarding the operating bypasses included in these specifications.

BACKGROUND By letter 2CAN099801 dated September 4,1998, ANO-2 reported a plant condition in accordance with 10 CFR 50.73(a)(2)(i)(B) where the automatic removal of operating bypass for the high logarithmic power trip function in the Reactor Protective System (RPS) was not within the required value listed in the TS. The referenced letter also stated that a TS change request would be submitted to establish setpoint requirements consistent with the plant design and the ANO-2 safety analyses. A review of the associated safety analyses has determined

! that the attached changes included in the TS change request are bounded by the current l ANO-2 analyses of record. The attached changes also modify the TS to reflect the original

! plant design.

1 3 Attachment to 2CAN099805 Page 2 of10 The ANO-2 Plant Protection System (PPS) contains operating bypasses that are used during routine startup and shutdown operations to prevent unwanted emergency safety feature system actuations and reactor trips when their protection is no longer required. These operating bypasses must be manually inserted when the permissive condition exists. The operating bypasses are designed for automatic removal when the plant conditions reach a point where the trip function is necessary. Once operating bypasses are automatically removed, they can not be reinstated until the permissive conditions return and the bypass switch is manually returned to the bypass position. The operating bypasses are capable of defeating or blocking all four channel trips for the specific trip fimetion if the permissives are ,

satisfied and operator action has been taken to activate the bypass in all four channels.

The ANO-2 TSs require the operability of the PPS operating bypasses in the limiting condition for operation (LCO) section of TS 3.3.1.1 and 3.3.2.1. The operating bypasses are also discussed in the table notations for these specifications and in the table notations of TS

2.2.1. These operating bypasses are for the CPC generated trips, the high logarithmic power level trip, and low pressurizer pressure trip. The CPCs generate two reactor trip signals that are sent to the PPS. The CPC generated trips are the low departure from nucleate boiling ratio (DNBR) and high local power density (LPD). The TSs allow the operating bypass for the high logarithmic power level to be initiated when power is above 10*4 power, thus disabling this trip function because it's no longer needed for reactor protection. The single bistable control of these functions ensures that CPC trip protection is automatically enabled i any time that a permissive exists to bypass the high logarithmic power level trip. l The CPC operating bypass essential
y block or disable the two CPC generated trips from actuating the RPS. The TSs allow the operating bypasses for the CPCs to be used if reactor power is less than 10*4 power; therefore disabling the CPC trip functions because they are no longer needed for reactor protection. Again, the single bistable control of these functions ensure that high logarithmic power level trip protection is automatically enabled any time that a permissive exists to bypass the CPC trips. The pressurizer pressure low operating bypass is ,

not affected by the conditions requiring this TS change and will therefore not be discussed in further detail.

Notation (a) of TS Table 3.3-1, " Reactor Protective Instrumentation," applies to the high logarithmic power trip. It states in part, the "... bypass shall be automatically removed when thermal power is 5; 10*A percent of rated thermal power." This note requires the operating bypass to be automatically removed before thermal power decreases below 10*A of rated thermal power (RTP). Note (c) of the same table is applicable to the CPC generated trips and states in part, the "... bypass shall be automatically removed when thermal power is 210*A of rated thermal power." This note requires the CPC operating bypass to be automatically removed before thermal power exceeds 10*A of RTP. Therefore, compliance with each l notation is only possible if the bistable were designed to actuate and reset at exactly the same setpoint with the bistable setpoint at exactly 10*4 of RTP. The present TS requirements for

, the operating bypass requirements for the CPCs and logarithmic power instrumentation are contained in the following table.

. _ _ - ~ _ - - . - - . - - - ...- . .- .-. - -_

  • At*=ch'-t to 2CAN099805 Page 3 of10 Present TS Operating Bypass Requirements for the CPCs and Logarithmic Power instrumentation TS Table Operating Present Requirements Bypass Notes Mode of Applicability d d Functional Table Table Below 10 % of RTP Above 10 % of RTP '

i Unit 2.2-1 3.3-1 The operating bypass Log r- is required to be This trip function may Note (1) Note (a) 2, 3*, 4*, 5*

automatically removed. be manually bypassed.

LPD - High Note (5) Note (c) 1, 2 This trip function may D*g, 'P' p s t

manuaHy WW. automatically removed.

l i

DNBR - Low This trip function may D* no pass i Note (5) Note (c) 1, 2 g, g manuaHy hpassed, automatically removed.

CPCs b pass Note (5) Note (c) 1, 2 This trip function may D','P'

to be manually bypassed, automatically removed.
  • With reactor TCBs closed and the CEA drive system capable of CEA withdrawal ANO-2, Waterford-3, and San Onofre-2 and 3 are of similar PPS vendor designs and all utilize a single bistable comparator to control the bypasa enable and automatic bypass removal features associated with the above referenced TS table notes. Waterford-3 has already
submitted a TS amendment request on this subject by letter dated September 11,1998.

The CPC operating bypass at ANO-2 is currently removed automatically at the "setpoint" value of the bistable on an increasing signal. The logarithmic power operating bypass is automatically removed at the " reset" value of the bistable on a decreasing signal. The reset d

value of the bistable (~0.794 x 10 %) is below its setpoint value by the hysteresis of the bistable which is approximately 100 milli-volts. This design makes it physically impossible to comply with both TS notes simultaneously because both functions can't be physically set at 10*4 power.

ANO-2 has established the bistable setpoint at a value that removes the CPC bypass before exceeding 10*4 power during -tartup. This results in the bypass for logarithmic power not being automatically removed until power decreases to a value that corresponds to the reset of the bistable which is less than 10*4 of RTP. This prevents compliance with notation (a) of TS Table 3.3-1 and notation (1) c TS Table 2.2-1 because there is a small range of power below 10*4 where the high logarit nic power bypass is not automatically removed due to

! the bistable hysteresis. An additional issue related to the bistable setpoint is that the 10*4 l setpoint value in ANO-2 TS does not include any instrumentation or process (core power 1- distribution effect) uncertainties.

l

  • Attachment to 2CAN099805 Page 4 of 10 ANO-2 was operating in Mode I when the above condition was discovered. TS 3.3.1.1 l (Table 3.3-1) does not require the operability of the high logarithmic power trip function to be l operable in Mode 1. The automatic bypass removal function for the CPC trips had already i been accomplished with their setpoints consistent with TS notation requirements. Therefore, l as long as ANO-2 operates in Mode 1, unlimited operation is allowed by the TS.

I Based on a review of the ANO-2 Safety Analysis Report (SAR) and input from the Nuclear >

I Steam Supply System vendor (ABB-CE), it has been determined that the 10*A setpoint has historically been considered as a " nominal" value. Nominal values in TSs have been typically deelt with more informally than other values. For example, nominal values typically require no offset in the conservative direction to accommodate such factors as potential instrument uncertainties. The nominal consideration of the 10*4 setpoint is believed to have been a factor in the condition having existed for approximately twenty years without being previously documented in various reviews to determine compliance with TS requirements.

In evaluating the root cause of this condition, ANO determined that tb M of the PPS with respect to the automatic removal of operating bypasses is consistem with the original l intent. Since the PPS design pre-dates implementation of the original TS, the root cause of this condition was attributed to a technical inaccuracy in wording of the original TS with respect to the plant design. A review of plant records covering the period when the error occurred failed to produce any additional insight into the specifics of considerations regarding the original wording.

1 DISCUSSION OF CHANGE l

~

i This TS change request is written for the ANO-2 single operating bypass bistable design and i establishes a range for this bistable to be set within. This range allows for conservative offsets relative to the bistable hysteresis and inclusion of margin for the applicable uncertainties.

When the TSs are revised to reflect the requested setpoint range, then the bistable can be set within this range and TS compliance will be restored. This change is being requested consistent with the associated safety analyses and the intent of the ANO-2 TS. Regardless of the actual bistable setpoint within this band, the design of this bistable ensures that either the CPC or the high logarithmic power level trips are available to provide reactor trip protection.

This TS change request proposes to establish a range between 10*A and 102% of RTP for the setpoint and reset values of this bistable in order to permit future TS compliance. The bistable setpoint will be suct that the CPCs will automatically come out of bypass before I thermal power exceeds 10*A _fIFP. The CPCs will be allowed to be manually bypassed below 10*4 of RTP. The requirer, ents for the high logarithmic power operating bypass will not be changed by the TS change request. The high logarithmic power-operating bypass will

, continue to be required to automaticM!y come out of bypass before power decreases below l 10*4 of RTP and will continuo to oc allowed to be manually bypassed above 10*4 of RTP.

i

  • Attachment to 2CAN099805 Page 5 of10 Although the TS will allow the manual bypass of these functions within this operating range, these bypasses can not be initiated until the associated permissive signal is received. If the bistable setpoint is adjusted to 10~5% power, the high logarithmic power trip will not be able to be bypassed during a reactor startup*until 10'8% power, although the proposed TS chan will allow it to be bypassed above 10 A power. This 10-8% setpoint would also prevent I manually bypassing the CPC trips until the bistable is reset at ~7.94 x 10*4 (~100 milli-volts i below 10' % power), although the proposed TS change will allow it to be bypassed below 10'8% power. The reset value of this bistable is also the point at which the high logarithmic power trip will automatically be enabled.

Associated Safety Analyses The following is a discussion of each of the associated safety analyses and why the proposed l range associated with this TS change request is acceptable. The CPCs provide the reactor trip protection for the CEA withdrawal events from critical conditions while the high logarithmic power trip provides the protection for the subcritical CEA withdrawal events and the uncontrolled boron dilution events. The withdrawal of CEAs or boron dilution adds positive reactivity to the reactor core that causes both the core power level and the heat flux to increase. Since these transients are initisted at low power levels, the normal reactor feedback '

mechanisms, moderator feedback, and Doppler feedback do not occur until power generation in the core is large enough to cause changes in the fuel and moderator temperatures. Each ,

event is described below.

CEA Withdrawal from Critical Conditions The CEA bank withdrawal event from hot zero power (HZP) critical conditions was I reanalyzed for the present ANO-2 operating cycle (Cycle 13) as part of the reload effort. This analysis is described in Section 15.1.2.4.1 of the ANO-2 SAR. For this event, the reactor is assumed to be critical and at a power level of 10*A. This value was chosen because it is the lowest power level at which the operating bypass for the high logarithmic power trip can be manually bypassed. That assumption also applies to this proposed amendment request. The high logarithmic power trips are assumed to be bypassed for this event. This action prevents the high logarithmic power trip from producing a reactor trip during this event. The low DNBR trip was not assumed to occur for this event. As stated in the SAR, the CPC variable overpower trip (VOPT) provides the reactor trip function for this event at an assumed value of 30% power.

l An uncontrolled CEA withdrawal is assumed to commence from the 10*A power level. The l CEA bank withdrawal is assumed to be operating at its maximum design speed. The CEA withdrawal produces a positive reactivity addition that results in a reactor power increase.

The resulting reactor trip is assumed to be caused by the CPCs at the minimum value for the VOPT. The CEA bank withdrawals continue until the CPCs produce the VOPT reactor trip

at 30% power. As indicated in the SAR, the results of this analysis produce acceptable results.

1 i

  • Attachment to 2CAN099805 Page 6 of10 The rate at which power is increasing at the time the CPC VOPT trip occurs is dependent on the' assumption of the initial power level at the start of the event. The CEA withdrawal event assumes a constant positive reactivity addition rate input for this analysis. The longer this event runs before the reactor trip is initiated, the more positive reactivity that is added to the core. When the event is initialized at a higher power level (i.e.10*A), there is a shoner l period of time for CEA motion prior to the trip. The reduced CEA motion results in a smaller positive reactivity addition at the time of the CPC trip. The smaller reactivity addition results in a reduced peak power level for this event and thus is bounded by the present safety analyses.

This TS change requests a range of 10*A to 10*4 of RTP for the operating bypass bistable  !

i setpoint. The enabling of the trip function for the CPCs will still occur decades before the ,

VOPT trip function is necessary. The present 10*4 analysis produces the most severe results l compared to any other case allowed by the proposed range and therefore bounds the remainder of the allowable range. The analysis of record was performed using the most conservative or worst case condition allowed by the proposed TS change and provided

! acceptable results. Therefore, increasing the allowable bistable setpoint within the proposed TS range of 10*4 to 10*4 of RTP is acceptable and has no effect on the current analyses.

CEA Withdrawal Events from Subcritical Conditions i

The analysis of this event for Cycle 13 is discussed in Section 15.1.1.4.2 of the ANO-2 SAR.

The RPS is designed to prevent such a transient from resulting in a minimum DNBR less than 1.25 by a high logarithmic power reactor trip. The high linear power level, CPC VOPT, high local power density, and low DNBR trips provide backup protection wlule the high pressurizer pressure trip provides protection for the reactor coolant pressure boundary.

The CEA withdrawal event from subcritical conditions was analyzed using approved computer codes. Two reactivity addition rates were considered,0.00025 Ap/sec and 0.0002 Ap/sec. These reactivity addition rates are consistent with the maximum addition rates expected for bank withdrawals near critical conditions. Due to the planned sequence of events for a controlled stanup, boron concentrations are maintained at levels which prevents criticality for most CEA bank withdrawals. Under certain conditions criticality can be attained with the right combination of CEA bank withdrawa, and boron concentration. Only CEA bank withdrawals that result in critical conditions are considered for this event.

CEA withdrawal commences as the event is initiated from subcritical conditions. The resulting positive reactivity addition causes the reactor to become critical. Reactor power continues to increase as CEA withdrawa! continues. The CPC operating bypasses are assumed to be automatically removed at 10*A of RTP. Reactor power continues to increase until a reactor trip is initiated by the high logarithmic power level trip at 0.75% of RTP.

The manual initiation of the high logarithmic power operating bypass only occurs during a contiolled power increase and thus these trips are not bypassed if the increase is due to an inadvertent CEA withdrawal. In addition, since there is only the short period of time between

  • Attachment to l 2CAN099805 l Page 7 of10 I the high logarithmic power level operating bypass permissive and the high logarithmic power level trip, it is assumed to remain an active trip and not bypassed As stated in the proposed TS change, the CPC operating bypasses are required to be automatically removed before ,

power exceeds 10*A of RTP. Since this analysis did not credit the CPC trips, raising the I allowable setpoint from 10*4 to 10*A for the automatic enabling of the CPC trips has no effect on this analysis. The reactor trip is caused by the high logarithmic power trip, which is not affected by this change.

During this event, the high logarithmic power level operating bypass permissive will be enabled as core power increases above the setpoint of the bistable within the proposed allowable range. The actual operating bypass permissive setpoint within the proposed range l does not matter for this case because this trip is not assumed to be bypassed and thus remains ,

available to trip the reactor. By moving the point at which this trip may be bypassed from l 10*A to 10*A of RTP, a shorter period of time will physically exist between the permissive l and the reactor trip setpoint. The rw action in time only helps to ensure the assumptions for this event remain valid.

Boron Dilution Event.

l The high logarithmic power trip is credited in the uncontrolled boron dilution event analyses. )

This event assumes the reactor is subcritical with an uncontrolled boron dilution event in  ;

l progress. The event continues until the resulting positive reactivity addition produces reactor i criticality. The CPC operating bypass is assumed to be automatically removed at 10*A of RTP. Reactor power continues to increase with the continued boron dilution until the high logarithmic power trip is received at 0.75% power. Although the CPC trips become available l during this event, they are not assumed to trip, and thus do not play a role in this analysis.

Therefore, modifying the point at which the automatic removal of the CPC operating bypass i occurs has no effect on this analysis.

The high logarithmic power level operating bypass permissive is assumed to be enabled as l core power increases above the present 10*A of RTP setpoint. Reactor power continues to l increase with the uncontrolled boron dilution until a reactor trip occurs at 0.75% power. The l actual operating bypass permissive setpoint within the proposed range does not matter for this case because this trip is not assumed to be bypassed and thus remains available to trip the reactor. By revising the point at which this trip can be bypassed from 10*A to 10*A of RTP, a smaller amount of time will physically exist between the permissive and the reactor trip setpoint. The reduction in time only helps to ensure the assumptions for this event remain valid. Therefore, the proposed changes have no adverse effects on the uncontrolled boron dilution event.

Logarithmic Power Channel Decalibration Part 21 Issue

The logarithmic pcwer channels are calibra;ed at 100% RTP with the reactor trip setpoint at l 0.75% power. The effects oflow power, low RCS temperature, or more l'eavily rodded conditions all contribute to reducing the neutron flux leakage to the excore detectors. These I

.- _ _ _ _ _ _ _ _ _ _ _ . _ . _ . _ _ _ _ _ _ . _ _ _ _ _ __ _~

' Attachment to 2CAN099805 Pags 8 of10 factors result in a decalibration of the detectors and are accounted for in the analysis. An investigation of this decalibration factor is described in CE NPSD-1052-P, "High Log Power Trip Function Generic Decalibration Evaluation." This investigation showed that the decalibration factor of 2 used in ANO-2 analysis contains additional conservatism. It has very little dependence on any power level within the proposed TS range. Raising the setpoint at which the operating bypasses are set does not affect the decalibration factor used. Therefore, the proposed changes included in this TS change request have no adverse effect on the logarithmic power channel decalibration factor used in the ANO-2 safety analyses.

Specific TS Page Changes The power level has been changed from 10*4 to 10*4 at which the CPCs may be bypassed and where automatic removal of the operating bypass is required in Table 2.2-1 notation (5) and 3.3-1 notation (c). The single bistable associated with these operating bypasses is designed with an inherent hysteresis loop and therefore requires an operating band. The band of 10*A to 10*A provides the bistable adequate operating space to account for the inherent bistable hysteresis, allow- for bistable drift, and to provide margin for the applicable uncertainties. Regardless of the actual bistable setpoint within this band, the bistable design ensures that either the high logarithmic power level or the CPC generated trips are available to provide reactor trip protection.

The remaining wording changes made to the below listed table notations have been requested to clarify the existing TS requirements. During the review of the 10*A bistable setpoint  ;

requirements, ANO determined that all of the table notations associated with the operating '

bypasses and their setpoints lacked clarity. The notations associated with the operating j bypasses have been revised to eliminate the need for future interpretation of these i requirements. The wording changes made to the below listed table notations are being requested to clarify the existing requirements and are therefore considered administrative in I nature. The following table notations have been revised and are included with this TS change  !

request: )

e Table 2.2-1 notations (1), (2), and (5),

e Table 3.3-1 notations (a), (b), and (c),

e Table 3.3-3 notation (a), and e Table 3.3-4 notation (1).

The LCO section of TS 3.10.3 has been modified to include the allowance to suspend the noted requirements of Table 2.2-1. TS 3.10.3 presently allows the suspension of the noted requirements of Table 3.3-1. Notations (a) and (c) of Table 3.3-1 discuss the same operating bypass bistables setpoints that are discussed in Table 2.2-1 notes (1) and (5). This change is considered administrative in nature because noted requirements (1) and (5) of Table 2.2-1 discuss the same operating bypass functions and setpoints as notations (a) and (c) on TaNe 3.3- 1. This change has been modified to be consistent with specification 3.10.3 of the Waterford-3 TS.

l

  • Attachment to 2CAN099805 Page 9 of10 The bases sections for specifications 2.2.1, 3.3.1.1, ar.d 3.3.2.1 were also modified by the r

addition of clarifying in ormation about the operating bypasses. The additional bases information further describes the operation of the high logarithmic power, CPC, and the low pressurizer pressure operating bypasses consistent with the above described changes. The changes associated with the bases changes are being made to clarify the requirements associated with the specifications. These changes are considered acceptable because they are considered administrative in nature.

DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION An evaluation of the proposed change has been performed in accordance with 10 CFR 50.91(a)(1) regarding no significant hazards considerations using the standards in 10 CFR 50.92(c). A discussion of these standards as they relate to this amendment request follows:

l Criterion 1 - Does Not Involve a Significant Increase in the Probability or Consequences of an Accident Previously Evaluated.

This technical specification (TS) change request modifies the power level at which two of the three operating bypasses can be set to operate. This change is necessary because the present plant bistable design requires a range for this bistable to operate within rather than a specific setpoint as required by the present TS. The single bistable associated with these operating bypasses is designed with an inherent hysteresis loop and therefore requires an operating range. The band of 10% to 10% of rated thermal power provides the bistable an alequate operating range to account for the inherent bistable hysteresis, allow for bistable drift, and provides margin for the applicable uncertainties. Regardless of the actual bistable setpoint within this band, the bistable design ensures that either the high logarithmic power level or the core protection calculator (CPC) generated trips are available to provide reactor trip protection. The CPC and logarithmic power operating bypasses and their setpoints are not considered credible accident initiators and therefore modifying their setpoints does not involve a significant increase in the probability of an accident previously evaluated.

The automatic removal function of these operating bypasses is designed to mitigate the consequences of accidents. As described within the background section of the TS change request, the safety analyses associated with these operating bypass-s have been reviewed for the acceptability of these changes. This review concluded that these changes are considered bounded by the existing safety analyses. Since these TS changes are bounded within the present safety analyses, they do not involve a significant increase in the consequences of an accident previously evaluated.

The remaining changes included in this TS change request are being made to clarify the existing requirements for the operating bypasses and to establish consistency with the above

! described changes. The remaining changes have been found acceptable because they are

Attachment to 2CAN099805 Page 10 of 10 l considered administrative in nature and have no effect on the probability or consequences of l an accident previously evaluated.

Therefore, this change does nol involve a significant increase in the probability or consequences of any accident previously evaluated.

Criterion 2 - Does Not Create the Possibility of a New or Different Kind of Accident from any Previously Evaluated.

l There are no physical plant modifications being made to the plant as a result of this change.

l The only function that is required by the TS and modified by this change is associated with the l allowed setpoint for the automatic bypass removal feature of the CPCs. This feature will still l be required by the TS, but will be allowed a slightly higher setpoint. The system connections and the reactor trip setpoints are not affeded by this change. The CPC and logarithmic power l operating bypasses and their setpoints are not considered as credible accident initiators.

l Therefore, this change does not 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.

l The safety analyses associated with these operating bypasses have been reviewed for the j acceptability of these changes. This review concluded that the changes associated with this TS change request are considered bounded within the existing safety analyses. The associated safety analyses have been considered to be acceptable because they have produced acceptable l results and thus provide an acceptable margin to safety. Therefore, this change does nol

involve a significant reduction in the margin of safety.

Therefore, based upon the reasoning presented above and the previous discussion of the amendment request, Entergy Operations has determined that the requested chande does nol l

involve a significant hazards consideration.

l l

!

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