ML20082M810
| ML20082M810 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 08/27/1991 |
| From: | Beck G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20082M812 | List: |
| References | |
| NUDOCS 9109060021 | |
| Download: ML20082M810 (12) | |
Text
.
I 10 CFR 50.90 TS 6.9.1.13 1*lllLADEl.l' Illa El,ECTRIC COMi%NY NUCl. EAR GROUP 11EADQUARTERS 955-65 CllESTERilROOK BIND.
WAYNE, PA 19087 $691 (215) 640 6000 NUCLEAR ENGINE l RING & St RYlCES DEPARTMENT i
August 27, 1991 :
Docket Nos. 50-35? I 50-35 License Nos. NPF-39 J NPF-85 :
U. S. Nuclear Regulatory Commission ATTN Document Control Desk Washington, DC 20555
SUBJECT:
Limerick Generating Station, Units 1 and 2 Technical Specifications Change Request and Submittal of Revised Current Cycle Specific Core Operating l Limits Reports l Gentlemen Philadelphia Electric Company is submitting Technical Specifications Change Request (TSCR) No. 90-12-0, in accordance with 10 CFR 50.90, requesting an amendment to the Technical '
Specifications (TS) (Appendix A) of Operating License Hos. NPF-39 and NPF-85. Information supporting this Change Request is ;
contajned in Attachment 1 to this letter, and the proposed replacement pages are contained in Attachment 2.
This submittal requests changes to incorporate new TS <
Section 3/4.7.8 regarding operability requirements for the main ;
turbine bypass system. This change is being proposed to take credit for main turbine bypass valve operation in the calculation of the minimum critical power ratio (MCPR) thereby giving tho i plant more MCPR margin (i.e., the feedwater controller failure would no longer be the limiting transient). The latest NRC .
approved Boiling Water Reactor (BWR) Standard TS (NUREG-0123, i Rev. 3, 1980) includes the main turbine bypass system operability i requirements. As a result, most BWR plants already have the main !
turbine bypass system operability requirements in their TS.
Therefore, this change is specific to Limerick Generating Station (LGS), Units 1 and 2.
9109060021 910S27 0\
PDR ADOCK 050003'52 P pga g\
i U.S. Nuclear Regulatory Commission August 27, 1991 Documont Control Desk Page 2 Also, enclosed are copies of the revised Core Operating Limits Reports (COLRs) for the current LGS, Unit 1, Reload 3, Cycle 4, and Unit 2, Reload 1, Cycle 2. These reports are being revised to provide the operating MCPR limits based on an operable main turbino bypass system, the minimum required number of operable bypass valves, and the maximum turbine bypass system response time. The revised COLRs will be used upon approval of the changes proposed in TSCR No. 90-12-0 to determine the operability of the main turbine bypass system, and to establish the appropriate operating limit MCPR based on the operability of the main turbine bypass system. Currently, the operating limit MCPRs for LCS, Units 1 and 2, are established based on the results of the feedwater controller failure, maximum demand without bypass transient (the most limiting transient).
Additionally, the format of the MCPR versus TAU (t) graphs in the Unit 1 COLR were revised to be consistent with the format of the similar graphs in the Unit 2 COLR.
These reports also provide the cycle-specific parameter limits fort Average Planar Linear Heat Generation Rate (APLHGR);
Flow Adjustment Factor (K,); Linear Heat Generation Rate (LHGR);
and Rod Block Monitor flow biased upscale and high flow clamped setpoints for the current LGS Unit 1, Reload 3, Cycle 4, and Unit 2, Reload 1, Cycle 2. These values have been determined using NRC-approved methodology and are established such that all applicable limits of the plant safety analysis are met. These revised reports are being submitted to the NRC in accordance with LGS Unit 1 and Unit 2 TS Section 6.9.1.12, and will be effective upon NRC approval of the changes proposed in TSCR No. 90-12-0 and issuance of the Amendments.
If you have any questions regarding this matter, please contact us.
Very truly yours, G1? t er,f' /b ll A
G. J. 13ec k , Manager Licensing Section GHS/eas Attachments Enclosures cc: T. T. Martin, Administrator, Region I, USNRC l T. J. Kenny, USNRC Senior Resident Inspector, LGS I T. M. Gerusky, Director, PA Bureau of Radiological Protection
,, '.~
. ' ' COMMONWEAloTH OF PENNSYLVANI A :
t as.
COUNTY OF CHESTER :
D. R. Helwig, being first duly sworn, deposes and says:
That he is Vice President of Philadelphia Electric Company; the Applicant herein;. that he has read the foregoing Application for Amendment of Facility Operating License Nos. NPF-39 and NPF-85 (Technical Specif1 cations Change Request No. 90-12-0) to incorporate main turbine bypass system operability requirements, and knows that the contents thereof; and that the statements and
-matters set forth therein are true and correct to the best of his knowledge, information and belief.
( %
/
Vice Presiden f
5 i
i Subscribed and sworn to l before me_this 9'# day f of 1991. !
d) %7 >
lJN$"?t fY ? -l1l. (
NotJIyJug 7 l c%%w E
e vaciegr122 wn ym W\ ,
F
ATTACllMENT 1 LIMERICK GENERATING STATION Units 1 and 2 Docket Nos. 50-352 50-353 License Nos. NPF-39 NPF-85 TECilNICAL SPECIFICATIONS CHANGE REQUEST
" Main Turbine Bypass System Operability Requirements" Supporting Information for Changes - 8'pages Y
]
.j
k l
I i
Philadelphia Electric Company (PEco), Licensee under i Facility Operating Licensos NPF-39 and NPF-85 for Limerick ,
Generating Station (LGS), Units 1 and 2, respectively, requests !
that the Technical Specifications (TS) contained in Appendix A of (
the Operating Licenses be amended as proposed herein to r incorporate operability requirements for the main turbine bypass ;
system. The proposed changes are indicated by a vertical-bar in l the margin of TS pages 11, xiv, xx1, 1-8, 3/4 2-8, and 3/4 2-9, new TS page 3/4 7-33, and new Bases page B 3/4 7-5 for both LGS Unit 1 and Unit 2 TS, and are contained in Attachment 2. l We request the changes proposed herein be effective upon f issuance of the Amendments. :
This Change Request provides a discussion and description of l the proposed TS changes, a safety assessment of the proposed TS
- i changes, information supporting a finding of No Significant ,
Hazards Consideration, and information supporting an i Environmental Assessment.
Discussion and Description of the Proposed Changes l The main turbine bypass system is a non-safety related !
system designed to control steam pressure when reactor steam ;
-generation exceeds main turbine requirements during plant startup, sudden load rejection, and cooldown. It allows a direct flow path for tnc cxcess steam flow from the reactor to the condenser without going through the main turbine. The bypass capacity of-the system is rated for 25% of the Nuclear Steam ;
Supply System rated flow. Sudden load reductions within the i capacity of the main turbine bypass system can be accommodated !
without initiating a reactor scram. The main turbine bypass ,
system consists or a nine valve steam chest connected to the main !
steam lines between the outboard main steam isolation valves and !
the turbine stop valves. Each of these nine valves is !
automatically operated by hydraulic cylinders, The bypass valves I are normally closed and the turbine electrohydraulic control (EHC) pressure regulator controls the turbine control valves directing all steam flow to the turbino. If the speed governor or the load limiter rertricts steam flow to the turbino, the regulator controls the system pressure by sequentially opening l the bypass valves. When the bypass valves open, the steam flows i l
from the bypass valve steam chest, through the connecting piping, I I to the pressure breakdown assemblies where a series of orifices l are used to further reduce the steam pressure before the steam [
enters the condenser. j i
The main turbine bypass system receives a signal to open the i
-bypass valves from the EHC pressure regulator whenever the actual !
steam pressure exceeds the preset steam pressure (lower than1the set point pressure for the main steam relief valves). This occursathen the amount of steam generated by the reactor can not be entirely utilized by the main turbine. The bypass valves open sequentially, and are used during normal startup and shut down.
. - , -- - ~ - - ~ . - - ---. . - - - - - - - . . . - - - . _ -
- l' Pago 2 If thoro is a full load rojection, all nino valves will open to ;
bypass a maximum of 25% of the design steam flow. The t operability of the bypass system will be datormined by the number i of operable main turbino bypass valves being greator than or equal to that speciflod in the cyclo specific Core Operating Limits Report (COLR). ;
The curreat operating limit minimum critical power ratio I (MCPR) for LGS Unit 1 and Unit 2 is based on the foodwater [
contro11or failure (FCP) without bypass transient. By j periodically verifying the operability of the bypass system, tho :
plant can take credit for the analysis of FCF with bypasu, and j thereby,. operate with a lower operating MCPR limit. Lowering the t operating limit MCPR will also help to offsot the MCPR penalty which accounts for normal fuel channel box bow. (Noto-that fuel channel boxes are not roused.) By taking credit for the bypass system operation, the FCF will no longer be the limiting ;
transient. Additionally, by taking credit for the operability of l
- the bypass system, the cycle specific analyses may be performed ;
for higher reactor feedwater pump runout flow. Therefore, the j high speed stops for the reactor feedwater pump turbines can bo ;
set at a higher speed without incurring a MCPR penalty. The >
higher stops will provido increased flexibility during off-normal l operation (i.e., two reactor feedwater pump operation versus the l normal configuraticn of three operating reactor feedwater pumps) ;
and transients. j i
-The proposed TS changes described below are requested in l order to implement this Change Roquest at LGS, Units 1 and 2. j All changes are reflected in the unit specific TS pages contained ;
in Attachment 2. j i
- 1. Revise the TS INDEX on page il to include "1.43A l TURBINE BYPASS SYSTEM RESPONSE TIME" to indicate the i addition of a new definition forfthe turbine bypass !
system response time to the Definitions section of TS.
- 2. Revise the TS INDEX on page xiv to include "3/4.7.8 l
-MAIN TURBINE BYPASS SYSTEM" to indicate the addition of j a new Limiting Condition for Operation (LCO) and new j Survo111ance Requirements (SRs' for the main turbino l bypass system to the Plant Sysuems section of TS. l l
- 3. Reviso the TS INDEX on page xxi to include "3/4.7.8 MAIN TURBINE BYPASS SYSTEM" to indicate the addition of new'TS Bases for the main turbine bypass system LCO and l SRs to.the Plant Systems section of the TS Bases. I
- 4. Add a now Definition, "1.43A TURBINE BYPASS SYSTEM ,
RESPONSE = TIME," to the Definitions section of TS on TS ;
page 1-8. The " Turbine Bypass System Response Time" is used to determine operability of the turbine bypass l
?
._ _ __,__._ _ _ . _ _ . . _ _ _ . _ _ _ _ _ _ _ _ _ _._ _ _ ., _ _.~__ _ _ _ w
Page 3 system based on satisfactory completion of the !
applicable proposed TS SR. I
- 5. Revise TS LCO 3.2.3 on TS page 3/4 2-8 regarding the Minimum Critical Power Ratio (MCPR) to include the requirement ". . . and the main turbine bypass system is OPERABLE per Specification 3.7.8, . . . " to indicate that the operating limit MCPR shall be determined as a function of the operability of the main turbine bypass system. Taking credit for the operability of the main turbine bypass system provides for lowering the operating limit MCPR.
- 6. Add new TS Action "C" associated with TS LCO 3.2.3 to TS page 3/4 2-9 which states, "With the main turbine bypass system inoperable per Specification 3.7.0, operation may continue provided that, within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, MCPR is determined to be greater than or equal to the MCPR limit as a function of the average scram time (shown in the CORE OPERATING LIMITS REPORT) main turbine bypass valve inoperable curve, times K, shown in the CORE OPERATING LIMITS REPORT." This proposed TS Action is necessary to establish the proper MCPR limit when thu main turbine bypass system is inoperable. The operating MCPR limits based on an operable main turbine bypass system are reflected in the revised current cycle specific COLRs for LGS, Units 1 and 2, respectively, which are enclosed with this Change-Request. The revised COLRs will be effective upon NRC approval of the changes proposed in this change Request and issuance of the Amendments. If the' proposed TS changes are approved by the NRC, the operating limit MCPRs based on an operable main turbine bypass system will continue to bo reflected in all subsequent cycle specific COLRs for LGS, Units 1 and 2, respectively.
- 7. Add new proposed TS LCO and associated SR 3/4.7.8,
" MAIN TURBINE BYPASS SYSTEM," to new TS page 3/4 7-33.
Proposed new LCO 3.7.8 specifies determining operability of the ma,the condition in turbine bypass for system, the applicability of the LCO, and the action required when the system is determined to be inoperable as stated below.
"The main turbine bypass system shall be OPERABLE as determined by the number of operable main turbine bypass valves being greater than or equal to that specified in the CORE OPERATING LIMITS REPJRT.
" APPLICABILITY: OPERATIONAL CONDITION 1, when THERMAL POWER is greater than or equal to 25% of RATED THERMAL POWER.
. -- . . . -_. - ~ - .
. i Page 4 [
f
" ACTION: With the main turbine bypass system ;
inoperable, restore the system to OPERABLE status !
within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or take the ACTION required by [
Specification 3.2.3.c." !
r The minimum required number of operable main turbine i bypass valves is specified in the re"ised current cycle j specific COLRs for LGS, Units 1 and 2, respectively, ;
which are enclosed with this Change Request. Thia l number will continue to be specified in all subsequent !
cycle specific COLRs for LGS, Units.1 and 2, l respectively. ;
Proposed new SR 4.7.8 specifies the necessary SRs to ensure operability of the main turbine bypass system as stated below. ;
"The main turbine bypass system shall be demonstrated OPERABLE at least once pers ;
i
- a. 31 days by cycling each turbine bypass valve i through at least one complete cycle of full i travel, j
- b. refueling cycle by performing a system functional i test which includes simulated automatic actuation, I and by verifying that each automatic valve (;
actuates to its correct position, and
- c. refueling cycle by determining TURBINE BYPASS SYSTEM RESPONSE TIME to be less than or equal to y the value specified in the CORE OPERATING LIMITS l REPORT." ;
The maximum turbine bypass system response time is l; specified in the revised current cycle specific COLRs for-LGS, Units 1 and 2, respectively, which are !
enclosed with this Change Request. This time will 5 continue to be specified in all subsequent cycle j specific COLRs for LGS, Units 1 and 2, respectively. j i
f
- 8. Add new proposed BASES section 3/4.7.8, " MAIN TURBINE j BYPASS SYSTEM," to TS Bases page B 3/4 7-5 which ;
provides the bases for the new proposed LCO and SRs for i the main turbine bypass system as stated below. [
"The required OPERABILITY of the main bypass system is }
consistent with the assumptions of the feedwater j
~'
controller failure analysis in the cycle specific transient analysis, j i,
_ _ _ . _ _ _ _ _ . . _- _ _ _ _ . ___ J
Page 5 "The main turbine bypass system is required to be OPERADLE to limit peak pressure in the main steam lines and to maintain reactor pressure within acceptable limits during events that-cause rapid pressurization such that the Safety Limit MCPR is not exceeded. With the main turbine bypass system inoperable, continued operation is based on the cycle specific transient analysis which has been performed for the feedwater controller failure, maximum demand with bypass ;
failure." :
Safety Assessment [
The main turbine bypass system limits the peak pressure in l the main steam lines and maintains reactor pressure within !
acceptable limits during events that cause rapid pressurization f such that the. safety limit MCPR is not exceeded. With the bypass !
system inoperable, modificaticns to the operating limit MCPR may ,
be applied to allow continued operation based on the cycle specific transient analysis which has been performed for the FCF, !
maximum demand with bypass failure so that the MCPR safety limit i is not violated during the FCF, maximum demand event. Sufficient j margin to this limit exists below 25% of Rated Thermal Power [
(RTP), and therefore, operability requirements for the main j turbine bypass system are only necessary when the plant is operating at-or above this power level.
The main turbine bypass system is assumed to function during ;
the design basis FCF, maximum demand event as analyzed in Chapter ,
15 of the Updated Final Safety Analysis Report (UFSAR). Opening I of the bypass valves during the FCF initiated pressurization j event mitigates the increase in reactor vessel-pressure which t affects the MCPR during_the event. Failure of the bypass' valves to open causes pressure in the reactor to increase, ultimately l lifting the main steam relief valves which discharge _the excess i steam to the containment suppression pool. UFSAR Chapter 15 includes an evaluation of the offects of reactor pressure increase on fuel thermal margin during possible pressurization ;
events. These analyses specified the operating limit MCPRs for the. initial core at-which the safety limit MCPR would not be [
exceeded during the_ pressurization accidents. The analysis in l UFSAR Chapter 15 was done for pressurization resulting from a i FCF, maximum demand with an operable bypass system transient. !
However, the most current cycle specific transient analysis was done for a FCF, maximum demand with an inoperable bypass system transient. The analyses showed that the FCF without bypass ;
tranpient results in the most limiting MCPR of all events i analyzed, and that fuel thermal margins during the event are j maintained provided the operating limit MCPR is appropriately i modified. Accordingly, implementation of the proposed main- I turbine bypass system TS will result in lowering the operating !
limit MCPR, thereby providing additional operating flexibility. !
4 i
Page 6 Information Supporting a Finding of No Significant Hazards consideration We have concluded that the proposed changes to the LGS TS, which specify operability requirements for the main turbine bypass system, de not constitute a Signif. cant flazards Consideration. In support of t' tis determination, an evaluation of each of the three standards set forth in 10CFRSO.92 is provided below.
- 1. The proposed TS changes do not involve a significant '
increase in the pro,bability or consequences of an accident previously evaluated.
The proposed TS changes specify requirements for verifying the operability of the main turbine bypass system, and do not affect any plant hardware, plant design, or plant systems. Therefore, the probability of an accident previously evaluated is unchanged by the proposed TS changes. ;
The main turbine bypass system limits the peak pressure l in the main steam lines and maintains reactor pressure q within acceptable limits during events that cause rapid f pressurization. Chapter 13 of the UFSAR includes an i evaluation of the effects of reactor pressure increase !
on fuel thermal margin during possible pressurization -l ovents. These analyses specified the operating limit i MCPRs for the initial core at which the safety limit i MCPR would not be exceeded during the pressurization j events. A31 subsequent operating limit MCPRs are j determined by the cycle specific tranuient analysis for !
LGS Unit 1 and Unit 2, respectively. Of the l pressurization events, the-FCF, maximum demand is !
currentlyfthe'most limiting. The cycle specific !
transient analysis indicates that the operating limit j MCPR is lower.for the FCF with an operable bypass system. Verifying the operability of the turbino l bypass system in accordance with the proposed TS i provides assurance that the system will operate and l perform its intended function of ensuring that the i safety limit MCPR is not exceeded should a FCF l transient occur while operating at the reduced ;
operating limit MCPR. Additionally, the proposed TS l will ensure that when the bypass system is inoperable, the operating limit MCPR is established to provide ;
sufficient margin such that the safety limit MCPR is !
not exceeded in the event of a FCF transient. Because j the cycle-specific transient analyses, including the ,
FCF with and without bypass transients, will be j performed and roflected in the COLR for all subsequent I cperating cycles for LGS Unit'I and Unit 2, l respectively, the operating limit MCPRs will be j t
i Page 7 r i
l i
established, based on operability of the turbine bypass system, to ensure that the safety limit MCPR is not i exceeded in the event of a FCF. Therefore, the i consequences of an accident previously evaluated are ,
not changed by the proposed TS changes. ;
i
- 2. The proposed TS changes do not create the possibility [
of a new or different kind of accident from any i accidant previously_ evaluated. l f
The proposed TS changes do not alter the design or :
function of any plant equipment, nor do they introduce
- any new operating confjgurations or failure modes. l Currently, the operating limit MCPRs for LGS, Units 1 }
and 2, are established based on the FCF without bypass
' transient. The proposed TS will result in lowering the ;
operating limit MCPR for an operable main turbine ;
bypass system, but will require appropriately revising the operating limit MCPR if-the main turbine bypass e system is inoperable. Accordingly, the FCF with and !
without_ bypass transients will continue to be analyzed i in the cycle specific transient analysis and reflected l in the COLR for each LGS unit to be used in conjunction j with the proposed TS. Therefore, the proposed TS .
changes do not create the possibilfty of a new or ;
different kind of accident from any accident previously [
evaluated.
r ;
- 3. The proposed TS changes do not involve a significant i q
reduction in a marqin of safety.
The pro,osed TS changes will ensure that the operating i limit MCPR,-as determined by the cycle specific j transient analysis for LGS Unit i and Unit 2, i respectively, will be established based on the !
operability of the main turbine bypass system such that !
the safety limit MCPR will not be exceeded in the event j of the occurrence of the analyzed transients. !
Therefore, the proposed TS changes will not reduce a ;
margin of safety. !
Information Supporting an Environmental Assessment
{
An environmental assessment is not required for the changes proposed by this Change Request because the requested changes conform to the critoria for " actions eligible for categorical exclusion," as specified in 10CFR51.22(c)(9). The requested changes will have no impact on the environment. The requested changes do not involve a significant hastrds consideration as discussed in the preceding section. The requested changes do not involve a significant change in the types or significant increase in the amounts of any effluents that may be released offsite. In i-
- _ . _ . _ _ _ . _ . _ _ . . _ . _ . _ _ _ _? 5 Paoe 8 j i
t i
addi t. ion , the proposed changes do not involve a significant !
increase in individual or cilmulative occupational radiation !
exposure. ;
i Conclusion ?
The Plant operations Review Committee and the Nuclear Review -j Board have reviewed these proposed changes t.o the TS and have I concluded that they do not involve an unreviewed saf et.y quest. ion, l or a significant hazarda consideration, and will not endanger the -
health and safety of the public. j i
r I
i t
i i
1
-i i
i P
h l
I I
i t
i I
i I
k i
i
. . . - - . _ _ _ - - - , - , - . _ . , , . _ . - . . . . . . . . _ . . _ _ . . . . _ _ . . ~ . _ __.._._... __ _ ..___ ___- _ .__._ -. _ _-._.__ _ _.-_ __ _ -. _ _____