ML20117H244
| ML20117H244 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 05/20/1996 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20117H247 | List: |
| References | |
| NUDOCS 9605280115 | |
| Download: ML20117H244 (14) | |
Text
. . ~ . . ~ .- . . . _
Station Support Department
& 10 CFR 50.90 !
V PECO NUCLEAR eccosee<9vco-ne v Nuclear Group Headquarters A UMr or PfCO Emecy 965 chestertnook Boulevard Wayne, PA 19087 5691 4
May 20,1996 Docket Nos. 50-352 l 50-353 I i
. Ucense Nos. NPF-39 i NPF-85 e
- U.S. Nuclear Regulatory Commission l Attn: Document Control Desk Washington, DC 20555
Subject:
Umerick Generating Station, Units 1 and 2
- Technical Specifications Change Request No.96-124 Gentlemen
l
, PECO Energy Company is submitting Technical Specifications (TS) Change Request No.
. 96-12-0, in accordance with 10 CFR 50.90, requesting an amendment to the TS (Appendix A) of
- Operating License Nos. NPF-39 and NPF-85 for Umerick Generating Station (LGS), Units 1 and 2, respectively. This proposed TS change involves revising TS Sections 3/4.4.9.2,
- ' 3/4.9.11.1,3/4.9.11.2, and the associated TS Bases 3/4.4.9 and 3/4.9.11, to more clearly describe that the Residual Heat Removal (RHR) system Shutdown Cooling mods of operation, in Operational Conditions (OPCONs) 4, " Cold Shutdown," and 5, " Refueling," consists of four (4)
" subsystems." in addition, the proposed TS change also includes administrative changes to TS
- Section 3/4.4.9.1 to ensure consistency in terminology regarding the description of Shutdown
' Cooling " subsystems." The proposed TS changes are consistent with the guidance delineated in the improved TS (i.e., NUREG 1433, Revision 1, " Standard Technical Specifications General, i Electric Plants BWR/4," dated April 1995) which indicates that the RHR Shutdown Cooling mode 4 of operation is comprised of two (2) loops and four (4) subsystems (i.e., two (2) subsystems per loop). This TS Change Request is being submitted under affirmation, and the required affidavit ;
- is enclosed. l l
. We are requesting that, if approved, the amendments to the LGS, Units 1 and 2, TS become effective within 30 days of issuance.
d If you have any questions or require additional information, please do not hesitate to contact us.
Very truly yours, G. A. Hunger, Jr.
Director Licensing 280000 Attachments Enclosure
((l i~ cc: T. T. Martin, Administrator, Region I, USNRC (w/ attachments, enclosure) l N. S. Perry, USNRC Senior Resident inspector, LGS (w/ attachments, enclosure)
- R. R. Janati, Director, PA Bureau of Radiological Protection (w/ attachments, enclosure) 9605280115 960520 PDR ADOCK 05000352 P. PDR a
COMMONWEALTH OF PENNSYLVANIA :
- as.
COUNTY OF CHESTER :
4 D. B. Fetters, being first duly swom, deposes and says:
That he is Vice President of PECO Energy Company, the Applicant herein; that he has read the foregoing Technical Specifications Change Request No. 96-12-0 for Umerick Generating Station, Units 1 and 2, Facliity Operating Ucense Nos. NPF-39 and NPF-85, conceming the configuration of the Residual Heat Removal (RHR) system during Shutdown Coohng operations, and knows the contents thereof; and that the 1
statements and matters set forth therein are true and correct to the best of his knobiledge, information, and belief.
~
. -s h .3 - tI Vice President Subscribed and sworn to i before me this 20 i day of 1996.
4 I
- 1 KAU 01+
o Notary Publ!c I
Notarial Seal Mary I ou Skrocki, Notary Public Tredyffrin Twp., Chester County My Commission Expires May 17.1999 f.bmber. Pennsytvarna Asmaaten of I r -
I l
l i
ATTACHMENT 1 UMERICK GENERATING STATION l UNITS 1 AND 2 Docket Nos. 50-352 50-353 License Nos. NPF-39 NPF-85 i TECHNICAL SPECIFICATIONS CHANGE REQUEST No. 96-12 I
' Describe Availability of Four Subsystems Associated With the Residual Heat Removal System Shutdown Cooling Mode of Operation' Supporting Information for Changes - 11 pages 1
I l
4 u
Attachment 1
- Page 1 of 11 i
PECO Energy Company, Licensee under Faculty Operating License Nos. NPF-39 atxi NPF 85 for Limerick Generating Station (LGS), Units 1 and 2, respectively, requests that the Technical S;,6cricetiene (TS) contained in Appendix A to the Operating Licenses be amended as proposed herein to revise TS
- Sections 3/4.4.9.2,3/4.9.11,1,3/4.9.11.2, and the associated TS Bases 3/4.4.9 and 3/4.9.11, to more i
clearly describe that the Residual Heat Removal (RHR) system Shutdown Cooling mode of operation consists of four (4) " subsystems." These TS sections pertain to plant operations during Operational
! Conditions (OPCONs) 4, " Cold Shutdown" and 5, ' Refueling." In addition, the proposed TS change also
- includes administrative changes to TS Section 3/4.4.9.1 to ensure cer W,cy in terminology regarding the description of Shutdown Cooling " subsystems
- The proposed TS changes are consistent with the guidance delineated in the improved TS (i.e., NUREG-1433, Revision 1, " Standard Technical l Specifications General Elactric Plants, BWR/4,* dated Apru 1995) which indicates that the RHR Shutdown
- Cooling mode of operation is comprised of two (2) loops and four (4) subsystems (i.e., two (2) l subsystems per loop). The proposed changes to the TS are shown on the attached mark-up of TS i pages 3/4 4-25,3/4 4-26,3/4 9-17,3/4 9-18, and TS Bases pages B 3/4 4-6 and B 3/4 9-2. The TS j pages showing the proposed changes are contained in Attachment 2.
l- PECO Energy is requesting that, if approved, the amendments to the LGS, Units 1 and 2, TS become l effective within 30 days of issuance of the amendments.
i This TS Change Request provides a discussion and description of the proposed TS changes, a bafety a- assessment of the proposed TS changes, information supporting a finding of No Significant Hazards Consideration, and information supporting an Environmental Assessment.
I j Discussion and Description of the Proposed Changes
- The proposed TS changes are consistent with the guidance delineated in the improved Technical L Specifications (i.e., NUREG-1433, Revision 1, " Standard Technical Specifications, General Electric Plants, j BWR/4," dated AprH 1996). Currently, when referring to the RHR Shutdown Cooling operations, the TS generally describe the system configuration in terms of " loops" (i.e., "A" and "B" loops). Each " loop" consists of a single heat exchanger, two (2) pumps, and associated piping and valves. The proposed
- changes maintain these general dt.scriptions, but introduce the concept of " subsystems" when
- describing the RHR Shutdown Cooling mode of operation in OPCONs 4 and 5, !n a manner consistent i
with guidance speclU in NUREG-1433, Revision 1.
i
{ NUREG 1443, Revision 1, Indicates that RHR Shutdown Cooling is comprised of two (2) " loops," with j sach loop consisting of two (2) " subsystems." The proposed changes wRl define an RHR Shutdown {
! Cooling ' subsystem" during OPCONs 4 and 5, as consisting of a heat exchanger (a passive component) 4 aligned, or capable of being aligned, to a single RHR pump. As a result, there wRI be four (4) RHR l Shutdown Cooling " subsystems" avaBable (i.e., two (2) ' subsystems
- comprising a single " loop"). These RHR Shutdown Cooling ' subsystems" and " loops" are described below.
'A' Loop Subsystems
. A" Heat Exchanger and 'A' RHR Pump
- A' Heat Exchanger and "C" RHR Pump !
- B' Loop Subsystems
- B" Heat Exchanger and *B" RHR Pump
- B" Heat Exchanger and "D" RHR Pump l
Attachment 1 Page 2 of 11 l l
l The requirements of TS Section 3/4.4.9.1, " Hot Shutdown," are not changed by this proposed TS change. In OPCON 3* (i.e., HOT SHUTDOWN condition with the reactor pressure vessel pressure j below the Shutdown Cooling cut-in pwm'd of 75 poig), the TS for Suppression Pool Spray and Suppression Pool Cooling requires that two (2) Indeoendent loops be operable in OPCONs 1,2, and 3.
As a result, both RHR heat exchangers are required to be operable throughout OPCON 3. Therefore, the changes to TS Section 3/4.4.9.1 are administrative only and provide for consistent use of terminology. The intent and requirements of this TS Section are.ogt changed.
The following provides a description of the existing, portinent TS requirements.
Current TS Reauirements
- 1) Section 3.4.9.1, " Hot Shutdown," currently requires that two (2) Shutdown Cooling mode loops of the RHR system be OPERABLE, and, unless at least one (1) recirculation pump is in operation, at least one (1) Shutdown Cooling mode loop be in operation with each loop consisting of at least:
- 2) Section 4.4.9.1, " Hot Shutdown," currently requires that at least one (1) Shutdown Cooling loop of the RHR system or attemate method be determined to be in operation l and circulating reactor coolant at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
- 3) Section 3.4.9.2, " Cold Shutdown," currently requires that two (2) Shutdown Cooling mode loops of the RHR system be OPERABLE, and, unless at least one (1) recirculation !
pump is in operation, at least one (1) Shutdown Cooling mode loop be in operation with i each loop consisting of at least:
- 4) Section 4.4.9.2, " Cold Shutdown," currently requires that at least one (1) Shutdown Cooling loop of the RHR system or altamate method be determined to be in operation and circulating reactor coolant at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
- 5) Section 3.9.11.1, "High Water Level," currently requires that at least one (1) Shutdown Cooling mode loop of the RHR system be OPERABLE and in operation with at least:
- 6) Section 4.9.11.1, "High Water Level." currently requires that at least one (1) Shutdown Cooling mode loop of the RHR system on attemate method be verified to be in operation and circulating reactor coolant at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
- 7) Section 3.9.11.2, " Low Water Level," currently requires that two (2) Shutdown Cooling mode loops of the RHR system be OPERABLE and at least one (1) loop be in operation, with each loop consisting of at least:
j Attachment 1 l Page 3 of 11 1
- 8) Section 4.9.11.2, " Low Water Level," currently requires that at least one (1) Shutdown ,
Cooling mode loop of the RHR system or altemate method be verified to be in operation and circulating reactor coolant at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The following provides a description of the proposed changes to the affected TS Sections.
hDDgsed TS Chanoes
- 1) Revise Section 3.4.3.1 to incorporate co c : stent terminology with respect to RHR Shutdown Cooling ' subsystems," to require that two (2) Independent RHR Shutdown Cooling " subsystems'shall be OPERABLE, and, with no recirculation pump in operation, at least one (1) RHR Shutdown Cooling " subsystem'shall be in operation.
l 2) Revise Section 4.4.9.1 to incorporate consistent terminology with respect to RHR l Shutdown Cooling " subsystems," to require that at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> verify one (1) independent RHR Shutdown Cooling "subsystom" or alternate method is operating.
l l 3) Revise Section 3.4.9.2 to incorporate the guidance delineated in NUREG-1433, Revision 1, which stipulates that two (2) RHR Shutdown Cooling subsystems shall be OPERABLE, and, with no recirculation pump in operation, at least one (1) RHR Shutdown Cooling ;
subsystem shall be in operation.
- 4) Revise Section 4.4.9.2 to incorporate the guidance delineated in NUREG-1433, Revision 1, which stipulates that once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> verify one (1) RHR Shutdown Cooling subsystem or recirculation pump is operating.
- 5) Revise TS Bases 3/4.4.9 to incorporate portions of the Bases description provided in NUREG-1433, Revision 1, conceming RHR system alignment and operation for Shutdown Cooling in OPCON 4.
- 6) Revise Section 3.9.11.1 to incorporate the guidance delineated in NUREG-1433, Revision
- 1, which stipulates that one (1) RHR Shutdown Cooling subsystem shall be OPERABLE and in operation.
l
- 7) Revise Section 4.9.11.1 to incorporate the guidance delineated in NUREG-1433, Revision 1, which stipulates that once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> verify one (1) RHR Shutdown Cooling subsystem is operating.
- 8) Revise Section 3.9.11.2 to incorporate the guidance delineated in NUREG 1433 Revision 1, which stipulates that two (2) RHR Shutdown Cooling subsystems shall be OPERABLE, and one (1) RHR Shutdown Cooling subsystem shall be in operation.
l
- 9) Revise Section 4.9.11.2 to incorporate the guidance delineated in NUREG-1433, Revision ,
1, which stipulates that once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> verify one (1) RHR Shutdown Cooling i subsystem is operating.
l 1
- 10) Revise TS Bases 3/4.9.11 to incorporate portions of the Bases description provided in NUREG-1433, Revision 1, conceming RHR system alignment and operation for Shutdown Cooling in OPCON 5.
l i
Attachment 1 Page 4 of 11 i l l
Safety Assessment The RHR system is comprised of four (4) independent loops Each loop contains a motor driven pump, piping, valves, instrumentation, and contrds. In addition, two (2) of the loops (i.e., 'A' and "B") contain i heat exchangers that are cooled by the Residual Heat Removal Service Water (RHRSW) system. The '
RHR system can be operated in one (1) of the fonowing four (4) different modes of operation. ;
- Low Pressure Coolant injection (LPCI) Mode !
- Suppression Pool Cooling Mode
- Shutdown Cooling Mode
- Containment Spray Cooling Mode - l l
In the Shutdown Coding mode of operation, the RHR system takes suction from the reactor recirculation system and discharges back to the reactor vessel via the reactor recirculation system. The functional :
design basis of the Shutdown Coding mode is to have the capability to remove decay and sensible heat l from the reactor primary system in order to reduce reactor coolant temperature to 125'F, approximately l 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> after the control rods have been inserted, and to permit refueling when the RHRSW temperature is less than 85'F. The plant can be shutdown using the capacity of a single RHR heat .,
)
l exchanger and related RHRSW cooling capabuity.
The Shutdown Coding mode of the RHR system is manually initiated and can be contrdled by an operator in the Main Control Room. Shutdown Cooling is.DQL required for accident mitigation. Two (2) i separate Shutdown Cooling loops are avaRable, and although both loops may be employed for l shutdown, the raector coolant can be brought to 212*F in less than approximately 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> with only 1 one (1) loop in operation.
The existing TS requirements for Shutdown Coding currently state that one (1) operable loop of )
Shutdown Coding is required during OPCON 5 when at High Water Level (i.e., TS 3.9.11.1), and two (2) operable loops of Shutdown Cooling are required during OPCONs 3*,4, and 5 when at Low Water Level (i.e., TS 3.4.9.1,3.4.9.2, and 3.9.11.2, respectively). This proposed TS change involves modifying the designations currently specified in the TS in accordance with the guidance stipulated in the Bases of NUREG-1433, Revision 1. This invdves revising the TS to stipulate operabRity of two (2) Shutdown Cooling " subsystems," with each " subsystem' consisting of one (1) RHR pump, heat exchanger, and piping flowpath. As a result, a Shutdown Cooling " subsystem" may be considered OPERABLE if it can be manually (locally or remotely) aligned for use. Therefore, even a single active component falure such as a Shutdown Cooling discharge valve faHure to open would not prevent operability of the associated Shutdown Cooling " subsystem", if the valve could be manuaHy opened This wRI permit, in OPCONs 4 and 5, the use of common passive components such as the heat exchanger and discharge piping.
The requirements associated with this TS Section are.agt changed, i.e., during Hot Shutdown (OPCON 3*) condition: two (2) indeoendent RHH Shutdown Cooling " subsystems
- wHI stHI be required to be i OPERABLE, meaning that both RHR heat exchangers, each with at least one (1) OPERABLE RHR pump, .
consnue to be required. The changes to TS Section 3/4.4.9.1 are administrative in nature and.dg.agt affect de Intent or requirements of this TS.
Tne use of common passive heat exchangers does not extend to TS Section 3/4.4.9.1, " Hot Shutdown," j or post-accident conditions, which are reflected in TS Sections 3.6.2.2 and 3.6.2.3 for operabHity of i Suppression Pool Spray and Suppression Pool Coding (also used for alternate Shutdown Cooling capablity). These requirements, which are not changed by the four (4) Shutdown Cooling " subsystem" ;
I designation, require the operabNity of two (2) independent loops in OPCONs 1,2, and 3, meaning two '
i
l Attachment 1 I Page 5 of 11 )
i 1
- (2) operable RHR heat exchangers and at least one (1) operable RHR pump por heat exchanger. In this 4
way, a single active failure occurring post-accident, when manual action is not avalable to correct the condition (e.g., the faRure of a Suppression Pool Cooling discharge valve to open), wNl not disable both Suppression Pool Cooling or Spray loops. l j
This position follows the guidance stipulated in the Bases of NUREG-1433, Revision 1, and credits the RHR Shutdown Cooling mode design at LGS as having four (4) potentiaHy avaNable " subsystems" (i.e., !
'A' RHR pump and "A" RHR heat exchanger; "C" RHR pump and "A" heat exchanger; *B' RHR pump and !
i
'B' heat exchanger; 'D' RHR pump and "B" heat exchanger; with the common suction piping and
- respective discharge piping). NUREG 1433, Revision 1, states
- '
"The two subsystems have a common suction source and are allowed to have a common heat exchanger and common discharge piping. Thus, to meet the LCO [of two operable SDC i i
subsystems], both pumps in one loop or one pump in each of the two loops must be operable. i Since the oloina and heat exchanoers are e---' comoonents that are naamied not to fan. thev ]
are aHowed to be cuiviii.cn to both loaired] anhaVstems.' l I
f The four (4) " subsystem" designation has no effect on the required operabbity of the RHRSW system. As !
l required by TS 3.7.1.1, the RHRSW subsystem (s) associated with the required operable RHR heat
' I exchanger (s) will continue to remain operable. Each operable RHRSW subsystem consists of two (2) operable pumps and the required operable flowpath to provide decay heat removal via the associated RHR heat exchanger, The RHRSW system piping is designed, fabricated, inspected, and tested in accordance with the l
requirements of ASME, Section ill, Class 3, and each RHRSW subsystem is single active faNure proof in !
that the fauure of a motor-operated valve, diesel generator, or pump does not prevent the system from performing its intended safety function.
The required avaNabNity of four (4) loops of the Low Pressure Coolant injection (LPCI) mode of RHR during OPCONs 1,2, and 3 as required by TS Section 3.5.1 is also not affected by the four (4)
" subsystem" Shutdown Cooling designation. No change to any RHR system instrumentation logic, required Emergency Core Cooling System (ECCS) avaNabulty, or method of operation is invcNed.
NUREG-1433, Revision 1, also re-affirms that each Shutdown Cooling " subsystem" is considerad operable if it can be manually aligned, remotely or locally, in the shutdown cooling mode for removal of decay heat. Thus, a LPCI-dedicated pump can be aligned for LPCI automatic initiation, yet s:lil be considered part of an operable Shutdown Cooling subsystem as long as it can be re-aligned for Shutdown Cooling.
Moderate Enerav Line Break (MFI R)
The designation of the LGS Shutdown Cooling mode of RHR as a four (4) subsystem design reflects the I current guidance stipulated in NUREG 1433 Revision 1, " Standard Technical Specifications, General Electric Plants, BWR/4," AprN 1995. NUREG-1433, Revision 1, states that for Shutdown Cooling operabuity in OPCONs 3*,4, and 5 (Low Water Level), the RHR heat exchanger and discharge piping ,
can be shared by the paired pumps in each loop since: "...the piping and heat exchangers are passive !
components that are assumed not to fan." This is an extension of the methodology that has previously l existed which credits the sharing between both 'A' and "B" RHR loops (and all four (4) RHR pumps) of
~
the common Shutdown Cooling suction piping, although requirements for attemate means of Shutdown Cooling suction (i.e., attemate Shutdown Cooling capabHity) have been analyzed since the Shutdown
i Attachment 1 Page 6 of 11 l
Cooling suction piping contains active coirpor,6iss (i.e., Shutdown Cooling suction valves H%051 1(2)
F008 and HWO51 1(2) F009 valves). Simaarfy, altemate means of retuming cooling water to the reactor pressure vessel (e.g., LPCI retum) have been analyzed in the event of falure of Shutdown Cooling retum valves.
The guidance specified in NUREG-1433, Revision 1, that the heat exchangers and piping are " passive" components, and assumed not to fan, is supported in OPCONs 4 and 5 in the NRC's Standard Review Plan (SRP), Section 3.6.1, " Plant Design for Protection Against Postulated Piping Falures in Fluid Systems Outside Containment
- This SRP section defines conditions for high and moderate energy line breaks (HELB/MELB), and states that essential systems and compor,6rds should be protected against postulated piping faRures in high or moderate energy fluid systems (i.e., RHR Shutdown Cooling is a j moderate energy system) that operate during normal plant conditions. Appendix A to this SRP section defines normal plant conditions as those occurring during startup, operation at power, hot standby (hot shutdown), or reactor cooldown to cold shutdown condition. COLD SHUTDOWN and REFUEUNG conditions are excluded from those requiring postulation of a HELB or MELB occurrence.
This is further supported by the SRP's statement that: "...the plant design for protection against [HELB l and MELB] piping fauures outside containment is reviewed to assure that such faRures would not cause l the loss of needed functions of safety-related systems and to assure that the plant could be safely shut down in the event of such faNures."
LGS Updated Final Safety Analysis Report (UFSAR) Section 3.6.1.1 lists the stated objectives of the HELB/MELB Program as: a.) shutting the reactor down safely; b.) maintaining primary containment l Integrity; and c.) maintaining off-site radiological doses below the requirements of 10CFR100. Whue i objective c.) is always applicable, objectives a.) and b.) do not apply to refueling operation conditions.
As indicated in UFSAR Section 3.6.1.1, the RHR system is designed, constructed, and inspected to ,
standards appropriate for nuclear safety systems. It can be reasoned that since the Shutdown Cooling l piping is always pressurized under all plant conditions, except when removed from service specifically i
! for maintenance, any leakage from a developing through-wall crack (the faRure mode of MELB piping) l l would be readHy discovered and repaired prior to the need for initiation of Shutdown Cooling. i in summary, the statements in NUREG-1433, Revision 1, SRP Section 3.6.1, and UFSAR Section 3.6.1,
! Indicate that the occurrence of pipe cracks in the common Shutdown Cooling discharge piping is not a credible faRure in OPCONS 4 and 5, and therefore, a MELB review is not required for Shutdown Cooling.
l l j[nale FaHure j The NUREG 1433, Revision 1, statement that the RHR heat exchanger is a passive component that is l
l assumed not to fat is consistent with the position that the single faRure criterion in this case applies to active components. Two (2) Shutdown Cooling subsystems are required in OPCONS 3*,4, and 5 (Low Water Level), despite the fact that one (1) Shutdown Cooling subsystem is adequate for decay heat removal under these plant conditions. This is to allow for the postulated faRure of an active component (e.g., a motor-operated valve or RHR pump). The NRC's report on the single faNure criterion, SECY 439, " Single Failure Criterion," makes the following statement:
" the probabHity of most types of passive faHures in fluid systems is sufficiently small that they need not be assumed in addition to the initiating faHure in application of the single failure criterion to assure safety of a nuclear plant."
A single active faHure is defined in both SRP Section 3.6.1, Appendix A, and LGS UFSAR Section 3.6.3
} as: "... considered to be a loss of component function as a result of mechanical, hydraulic, pneumatic, or electrical malfunction, but not the loss of component structural integrity." Thus, the loss of an active
Attachment 1 Page 7 of 11 r.
component, whether shared between common subsystems such as a motor-operated valve, or particular to an individual subsystem, such as a pump, does not mean a loss of pressure boundary integrity of the common portions of the subsystems, and a further passive component falure or pipe break need not be assumed The accident analyses in Chapter 15 of the LGS UFSAR discuss how single active fature criteria are applied to design basis accidents, and how single active falures and single operator errors are applied to transient events. By definition, these analyses are not required to assume the fagure of passive fluid system conyca.nm. UFSAR Section 15.2.9 detals the analyses of the falure of RHR Shutdown Cooling, and identifies the worst case single fagure as that of a Shutdown Cooling suction valve. The Nuclear Safety Operational Analysis in UFSAR Section 15.9 includes Event 18 as loss of Shutdown Cooling and states that for most single falures, Shutdown Cooling is re-established using redundant equipment. For fauure of the Shutdown Cooling suction line, attemate Shutdown Cooling is established
( utuizing suction from the suppression pool. No passive faBure of the heat exchanger is required to be postulated for these analyses.
l
- l. The design basis for operabuity of Shutdown Cooling with a single active faRure is met through the
! availabHity of the altemate cooling flowpaths. As stated in UFSAR Sections 15.2.9 and 15.2.9.3.4.2, the l first action to be taken upon the (worst case) faRure of a Shutdown Cooling suction valve is to gain l
access to the suction line and attempt to effect repairs. If this can not be accomplished, altemate cooling flowpaths are established in accordance with the remaining functional systems assuming, as an additional faNure, the loss of an electrical division With the four (4) " subsystem" Shutdown Cooling configuration, in the event of a falure of a Shutdown Cooling retum valve or check valve, manual actions l to effect repairs of the valve wRI be taken. Should these actions fan, the same analyzed attemate available flowpaths used for falure of a suction valve wRl allow for retum of cooled water to the reactor vessel. Hence, with four (4)
- subsystems" of Shutdown Cooling, the requirement for continued avaHabuy of Shutdown Cooling following single active faRures continues to be satisfied.
AC and DC electrical power for the RHR subsystems' pumps is provided by separate divisions from both offsite and onsite sources. Thus, although Appendix R fires need not be postulated during shutdown conditions, faRure of an electrical division can not prevent the redundant RHR subsystems, with avalable manual corrective action as required, from performing the Shutdown Cooling functions. !
l Other Considerations
! Whue not required to be postulated per NUREG-1433, Revision 1, as discussed above, the passive faHure of the RHR heat exchanger in the form of a tube leak has been considered. In such an event, the RHR fluid would leak into the RHRSW, potentially contaminating the Spray Pond and/or cooling tower basin.
If the leak were quantified and determined to be minor, the decision to continue normal Shutdown
- Cooling operation could be made, with radiological effects confined to the station. The potential for
[ release to the offsite environment would need to be carefully evaluated, but any effect on RHR Shutdown Cooling efficiency would be very small (i.e., the abuity of the system to continue to provide the necessary cooling would not be significantly affected).
Other station procedures address the steps necessary in the event of a loss of Shutdown Cooling. In addition, attemate methods of decay heat removal could be applied (i.e., Reactor Water Cleanup, Spent Fuel Pool Cooling once flooded up, etc.) to augment any reduced RHR effectiveness Existing i
!. procedures identify the effectiveness of these methods and at what period of time following reactor I shutdown they can be considered as sufficient to remove all generated decay heat.
! These temporary compensatory measures could be taken in addition to expediting the restoration of the out-of-service RHR heat exchanger for removal of decay heat.
Attachment 1 Page 8 of 11 I
.6MIESQf i
The proposed TS changes are being requested to more clearly describe the RHR system configuration associated with the Shutdcwn Cooling mode of operation in OPCONs 4 and 5. These TS proposed l changes are being made in accordance with the guidance stipulated in NUREG-1433, Revision 1, as it !
relates to Shutdown Cooling operations in OPCONs 4 and 5.
Information Supportina a Finding of No Sinnificant Hazards Consideration l
We have concluded that the proposed changes to Limerick Generating Station (LGS), Units 1 and 2, Technical Specifications (TS) to revise TS Sections 3/4.4.9.1,3/4.4.9.2,3/4.9.11.1, 3/4.9.11.2, and the associated TS Bases 3/4.4.9 and 3/4.9.11, to incorporate the guidance stipulated in NUREG-1433, Revision 1, " Standard Technical Specifications General Electric Plants, BWR/4,* dated AprH 1995, ;
pertaining to the Residual Heat Removal (RHR) system Shutdown Cooling mode of operation, do not 1 involve a Significant Hazards Consideration. In support of this determination, an evaluation of each of 1 the three (3) standards set forth in 10 CFR 50.92 is provided below.
- 1. The Dioeceed Technical Soecifications (TS) chanoes do not involve a s eniTcant incr==a in the orahahnity or conaaanances of an =mirlwit orevlanaiv evah= tart.
The proposed TS changes do not involve any physical changes to plant structures systems, or components. The RHR Shutdown Cooling mode of operation is manually controlled and is.ogt required for accident mitigation. The RHR system wRl continue to function as designed in all modes of operation. The consequences of equipment malfunction are not changed from those in existing analyses, with no increase in onsite or offsite radiological effects. The RHR system wRI continue to function as designed to mitigate the consequences of an accident and resultant onsite and offsite radiological effects remain as previously evaluated. The proposed TS changes whi revise the TS to more clearly describe the RHR system configuration in OPCONs 4 and 5. The proposed changes are consistent with the guidance stipulated in NUREG-1433, Ravision 1.
The four (4) " subsystem" Shutdown Cooling designation permits operability of only one (1) RHR heat exchanger for Shutdown Cooling service in Operational Conditions (OPCONs) 4 and 5, as long as both associated RHR pumps are operable and alignable for Shutdown Cooling. TS requirements for RHR Shutdown Cooling operation in Hot Shutdown, Suppression Pool Spray, and Suppression Pool Cooling continue to require two (2) Indeoendent loops to be operable in OPCONs 1, 2, and 3*, meaning both RHR heat exchangers wNI stdl be required to be operable throughout OPCON 3.
The four (4) " subsystem" Shutdown Cooling designation has no effect on the required operabNity of the Resic'ual Heat Removal Service Water (RHRSW) system. As required by TS Section 3.7.1.1, the RHRSW subsystem (s) associated with the required operable RHR heat exchanger (s) will continue to remain operable. Each operable RHRSW subsystem consists of two (2) operable pumps and the required operable flowpath to provide decay heat removal via the associated RHR heat exchanger.
The RHRSW system piping is designed, fabricated, inspected, and tested in accordance with the requirements of ASME, Section lil Class 3, and each RHRSW subsystem is single active falure proof in that the falure of a motor-operated valve, diesel generator, or pump does not prevent the system from performing its safety function.
Attachment 1 Page 9 of 11 4
The required avalabulty of four (4) loops of the Low Pressure Coolant injection (LPCI) mode of RHR during OPCONs 1,2, and 3 as required by TS Section 3.5.1 is not impacted by the four (4)
- subsystem" Shutdown Cooling designation. No change to any RHR system instrumentation logic, required Emergency Core Cooling System (ECCS)
. avalablity, or method of operation is involved.
NUREG-t433, Revision 1, also re-affirms that each Shutdown Cooling ' subsystem" is considered operable ll It can be manuaNy aligned, remotely or locany, in the shutdown cooling mode for removal of decay heat. Thus, a LPCI dedicated pump can be aligned for LPCI automatic initiation, yet stBI be considered part of an operable shutdown cooling subsystem as long as it can be re-aligned for Shutdown Cooling.
Therefore, the proposed TS changes do not invdve an increase in the probabulty or consequences of an accident previously evaluater;.
- 2. The orm-i TS channes do not cra='a the nos9blity of a new or different kind d 3 accident from any accident previousiv evaluatd The proposed TS changes do not involve any physical changes to plant structures, systems, or corr.ponents. The RHR system wil continue to function as designed in all modes of operation. No new accidant type is created as a result of the proposed changes. No new faRure mode for any equipment is created. The changes are 4
consistent with the guidance provided in NUREG-1433, Revision 1, pertaining to RHR Shutdown Cooling operation in OPCONs 4 and 5.
The four (4) " subsystem" Shutdown Cooling designation has no effect on the required operabulty of the RHRSW system. The RHRSW sebsystem(s) associated with the required operable RHR heat exchanger (s) win continue to remein operable as required by TS Section 3.7.1.1. Each operable RHRSW suleystem consists of two (2) operable pumps and the required operable flowpath to provide decay beat removal via the associated RHR heat exchanger.
The RHRSW system piping is designed, fabricated, inspected, and tested in accordance with the requirements of ASME, Secticn lil, Class 3, and each RHRSW subsystem is single active faRure proof in that the failuio of a motor-operated valve, diesel generator, or pump does not prevent the system from performing its safety function.
The required avaBabulty of four (4) loops of the LPCI mode d RHR during OPCONs 1,2, 4
and 3 as required by TS Section 3.5.1 and 3.5.2 is no' lmpacted by the four (4)
" subsystem" Shutdown Cooling designation. No change to any RHR system 4-instrumentation logic, required ECCS avaBabBity, or method of operation is involved.
NUREG-1433, Revis6on 1, also re-affirms that each E hutdown Cooling " subsystem" is considered operable if it can be manuaHy aligned, remotely or locally, in the Shutdown
- Cooling mode for removal of decay heat. Thus, a LPC!-dedicated pump can aligned be
. for automatic LPCI initiation, yet stHI be considered part of an operable shutdown i cooling subsystem as long as it can be re-aligned for Shutdown Cooling.
Therefore, the proposed TS changes do not create the possibuity of a new or different kind of accident from any accident previously evaluated.
l l Attachment 1 Page 10 of 11 l
- 3. The oronomad TS chanoes do not involve a slanificant reduction in a marain of safety.
Although the Bases for TS Sections 3/4.4.9.2,3/4.9.11,1, and 3/4.9.11.2 are being revised in support of this proposed TS change, the changes only involve providing 4 clarification regarding the designation of the RHR Shutdown Cooling operation !
configuration in OPCONs 4 and 5. The proposed TS changes.dQ.QQL involve any physical changes to plant structures, systems, or components. The RHR system wil continue to function as designed in all modes of operation. The consequences of equipment malfunction are not changed from those in existing analyses, with no ;
increase in onsite or offsite radiological effects. The RHR system wRl continue to function as designed to mitigate the consequences of an accident and resultant onsite 4 and offsite radiological effects remain as previously evaluated. The proposed changes i are consistent with the guidance stipulated in NUREG-1433, Revision 1.
The four (4) " subsystem" Shutdown Cooling designation has no effect on the required operabuity of the RHRSW system. As required by TS 3.7.1.1, the RHRSW subsystem (s) associated with the required operable RHR heat exchanger (s) wil continue to remain operable. Each operable RHRSW subsystem consists of two (2) operable pumps and the required operable flowpath to provide decay heat removal via the associated RHR heat exchanger.
The RHRSW system piping is designed, fabricated, inspected, and tested in accordance with the requirements of ASME, Section lit, Class 3, and each RHRSW subsystem is single active faRure proof in that the falure of a motor-operated valve, diesel generator, or pump does not prevent the system from performing its safety function. (in the same manner that manual action may be required for RHR system alignment in OPCONs 4 and 5 with one (1) RHR heat exchanger operable, a falure of the motor-operated RHRSW inlet or outlet heat exchanger isolation valves may require manual positioning for the required alignment.)
The required avaRabuity of four (4) loops of the LPCI mode of RHR during OPCONs 1,2, and 3* as required by TS Section 3.5.1 is not affected by the four (4) " subsystem" i Shutdown Cooling configuration. No change to any RHR system instrumentation logic, j required ECCS availability, or method of operation is involved.
l NUREG-1433, Revision 1, also re-affirms that each Shutdown Cooling " subsystem" is considered operable if it can be manually aligned, remotely or locally, in the Shutdown Cooling mode for removal of decay heat. Thus, a LPCI-dedicated pump can be aligned for LPCI automatic initiation, yet still be considered part of an operable Shutdown Cooling ' subsystem" as long as it can be re-aligned for Shutdown Cooling.
Therefore, the proposed TS changes do not involve a significant reduction in a margin of safety.
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Attachment 1 Page 11 of 11 l
information Supporting an Environmental Assessment l An Environmental Assessment is not required for the changes proposed by this Change Request 1 because the requested changes to the LGS, Units 1 and 2. TS conform to the criteria for " actions eligible j for categorical exclusion," as specified in 10 CFR 51.92(c)(0). The requested changes will have no impact on the environment. The proposed charvjes do not involve a significant hazards consideration as discussed in the preceding section. The proposed changes do not involve a significant change in the types or significant increase in the amounts of ariy viituent that may bc released offsite. In addition, the proposed changes do not involve a significant increase in individual or cumulative occupational radiation exposure. .
Conclusion The Plant Operations Review Committee and the Nuclear Review Board have reviewed the proposed l changes to the LGS, Units 1 and 2, TS and have concluded that they do not involve an unreviewed i safety question, and will not endanger the health and safety of the public. l l
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