ML20245F925
| ML20245F925 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/20/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20245F914 | List: |
| References | |
| NUDOCS 8906280295 | |
| Download: ML20245F925 (11) | |
Text
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%j UNITED STATES I
[
g NUCLEAR REGULATORY COMMISSION 73 E
WASHINGTON, D. C. 20665
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l SAFETY EVALUATION BY THE C'?itE OF NUCi. EAR REACTOR REGULATION i
r SUPPORTING AMENDMENT 5.
27' TO. FACILITY OPERATING LICENSE NO. NPF-39 i
PHILADELPHIA ELECTRIC COMPANY LIMERICX GENERATING STATION,. UNIT 1 DOCKET N0. 50-352
1.0 INTRODUCTION
H By letter dated April 10, 1989, Philadelphia Electric Company (the
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licensee) requested an amendment to Facility Operating License No. NPF-39 j
for the Limerick Generating Station,(TS) for the Residual Heat Removal Unit 1.
The proposed amendment would s
revise the Technical Specifications Service Water (RHRSW) and the Emergency Service Water (ESW) Systems to reflect operation of Limerick, Unit 2.
2.0 DISCUSSION TheResidualHeatRemovalServiceWater(RHRSW)systemisa safety-related system designed to supply cooling water to the RHR heat exchangers of both units / The RHRSW system is coninon to both reactor units and consists of two loops. Each loop services two RHR heat exchangers (one RHR heat exchanger in each unit) and provides sufficient 1
cooling for safe shutdown cooling and accident mitigation of both units.
l The two RHRSW system return loops can be cross-connected for operational
.i flexibility. Two valves in series are provided on the cross-connect, so a failure in one loop could be isolated from the other loop and, thus, not affect the operation of the other loop. Each loop has two pumps located in the spray pond structure. The RHRSW pumps take suction from the spray pond, circulate this water through the tube side of the RHR heat exchangers and return the water to the spray pond. One pump has the capability to supply 100% flow to one RHR heat exchanger in the associated loop. During two-unit operation, there are two heat exchangers (one per unit) required for safe shutdown and accident mitigation of both units (see figure 1).
The RHRSW system is available for normal shutdown or emergencies, and does not usually operate during power operation. However, the RHRSW system can be used in conjunction with the RHR system suppression pool cooling mode to maintain the suppression pool below specified temperature limits.
l The RHRSW return piping from the RHR heat exchangers and the return l-piping from the corresponding Emergency Service Water (ESW) loop share a common return header to the spray pond or cooling tower. Loss of the RHRSW/ESW return loop does not affect the capability of the second return l
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. loop to safely shut down either or both units during emergency 1
conditions. One pump in each loop (A and B) is powered from Unit 1 power supplies and, in the event of a loss of power, backup supply is provided from Unit 1 emergency diesel generators (EDG). The other pump in each loop-(C and D) is similarly pnwered from Unit 2 and Unit 2 EDGs (following receipt of the Unit 2 operating license). This configuration exists due to the common design of the RHRSW system and must be recognized by operators when entering any Action statement for RHRSW. The importance of recognizing the interdependency on the other unit's emergency diesel generators is reflected in the proposed changes to the TS.
The proposed changes to the TS for the RHRSW system are as follows:
Page 3/4 7-1, Section 3.7.1.1 l
Existing Actions a.1 and a.2 are combined into Action a.1.
This will allow any single RHRSW pump to be inoperable for 30 days, 3
eliminating the 92 day allowed outage time for inoperable RHRSW pump C or D.
Existing Action a.3 will now be renumbered as a.2 and modified to address any single RHRSW pump in each subsystem inoperable versus the specific combination cf the A RHRSW pump in one loop and the B RHRSW pump in the other loop. This change addresses the C and D RHRSW pumps in the same' fashion as the A and B RHRSW pumps. The allowed outage time for this Action will be 7 days.
Existing Action a.4 and a.5 will now be renumbered as a.3 and a.4 respectively.
No specific technical change is proposed.
New Actions a.5, a.6 and a.7 are incorporated. These Actions, and an associated footnote, address RHRSW pump / diesel generator pairs to assure that combinations of RHRSW pumps and/or emergency diesel generators (EDG) inoperabilities do not adversely affect the ability of the facility to respond to an event with a loss of offsite power.
Because the RHRSW system is common to Unit 1 and Unit 2 and the C and D RHRSW pumps are powered from Unit 2 EDGs on a loss of power, consideration for combinations of inoperable RHRSW EDGs (including Unit 2 EDGs which power RHRSW components) pumps and for safe operation of Unit 1 is specified.
Surveillance 4.7.1.1.b is being deleted. The function of the RHRSW radiation monitor is addressed by LCO 3.3.7.11.
Its presentation in the RHRSW system specification results in inappropriately declaring RHRSW inoperable if its radiation monitor is inoperable.
Editorial changes to add "-Common System" to the title, identify the RHR heat exchanger in the LC0 as the " Unit 1" RHR heat exchanger and delete reference to TS 3.4.9.1 in the LCO.
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4 The Emergency Service Water (ESW) system is a safety related system, designed to supply cooling water to selectea equipment on both Limerick Unit I and Unit 2 during a loss of offsite power condition and/or loss-of-coolantaccident(LOCA).
It is. comprised of two' independent loops (AandC,orBandD).
Each pump is capable of supplying 100% flow through its respective loop. Each pump can supply four emergency diesel generators (EDG) (two per unit) and all other required cooling loads for safeshutdownforbothunits(seefigure2).
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The A and B pumps.are powered from Unit i buses. Presently the C and D pumps are temporar_ fly _ powered from Unit 1 buses. Following receipt of the Unit 2 Low Power Operating License, emergency backup power for the C
' and D ESW pumps will be supplied from the Unit 2 emergency diesel.
- generators. The importance of this interdependency to Unit 2 diesel generators is reflected in Action statement a.4 of the proposed Technical Specification.
The proposed changes to the TS for the ESW system are as follows:
Pages 3/4 7-3. Section 3.7.1.2 Act. ion a.3 and associated footnote **, Action b.1 and Action b.2 (renumbered Action c.1) are rewritten for clarity. No specific technical change is proposed.
New Actions a.4 and a.5 are proposed. These Actions, and an associated footnote, address ESW pump / diesel generator pairs to assure that combinations of ESW pumps and/or EDG inoperabilities do not adversely affect the ability of the facility to respond to an event with a loss of offsite power. Because the ESW system is common to Unit I and Unit 2, and the C and D ESW pumps are powered from Unit 2 EDGs on a loss of power, consideration for EDGs (including Unit 2 EDGs that power ESW components) for safe operation of Unit 1 is specified.
Existing Action e is deleted since Limerick Unit 2 is now interconnected per the design for two unit operation.
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Surveillance 4.7.1.2.b requires that certain ESW tests be performed "during shutdown." Since ESW is a system comon to both Unit 1 and Unit 2, performance of the test may be required when only one unit is shutdown. Therefore, the other operating unit could not take credit for the performance of the test as it would not strictly meet the requirement of "during shutdown." To allow the flexibility to perform ESW testing without requiring both units to be shutdown,
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4.7.1.2.b is being revised to delete "during shutdown."
l Editorial changes to add "-Common System" to the title and i
specifically identify the associated flow path in the LCO as " Unit I
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4 revise and expand the Bases.(ges to the TS, the licensee proposes topages B 3/4 7-In addition to the above chan two-unit operation and the design bases requirements.
3.0 EVALUATION' The RHRSW and.ESW systems are common to both Limerick Units 1 and.2. The tie-in of the pumps and the arrangement of the power supplies (both-offsite and on-site power sources) were evaluated by the. staff in the early 1980s when both units were still under construction. The tie-in power supply arrangement was approved in the staff's SER (NUREG-0991).
Before Unit I was licensed, construction of Unit 2 was halted by Order of 1
.the Pennsylvania Public Utility Commission and, at the time, it appeared doubtful that construction of Unit 2 would be resumed. Even though.the arrangement of cross-tie piping, pumps and power supplies was approved, the staff did not focus on what the detailed TS requirements should be for two-unit operation, because two-unit operation was very doubtful. The Unit 1 TS that were issued with the Unit 1-operating license on August 8, 1985 were developed based on one-unit operation with backup from Unit 2 components..The RHRSW and ESW pumps for Unit 2 were in place and operational and were included in the Unit 1 protected area. There were
" temporary" piping arrangements to permit their use to support Unit 1.
With the. spare support components from Unit 2, the TS that were issued with the Unit.1 license permitted extended out-of-service times for inoperable equipment compared to the Standard BWR TS for a two-unit facilit Inasmuch as these are shared common systems between Units 1 and 2 (y.like the common control room) and the same operators are trained, certified and rotated between units, the TS for Unit 1 must be the same as those developed for Unit 2.
This amendment revises the Unit 1 TS to the same as the Unit 2 TS certified on June 2, 1989 and that will be issued with the Unit 2 license.
The Limerick Unit 1 TS, as currently written, reflect that Limerick Unit 2 has been under construction and credit is taken for the ability to utilize RHRSW pumps associated with Unit 2 in the Unit 1 TS. Specifically, the RHRSW TS contain special provisions for operation of all four RHRSW pumps while the piping leading to the Unit 2 portion of the RHRSW system was. isolated through the use of blind flanges within the Unit 1 Protected Area Boundary.
The proposed changes to the Action Statements in the Limiting Condition for Operation and the Surveillance Requirements for the RHRSW system reflect two-unit operation of LGS, including the operability of the Unit 2 electrical sources that power the
'C' and 'D' RHRSW pumps.
In addition, the operability of the Unit 2 emprgency diesel generators and the additional Unit 2 equipment will relieve operhting restrictions on Unit 1, which currently exist due to the interconnection with a unit under construction, and will improve overall system reliability. This relief is reflected in the proposed changes to the TS.
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' The present TS for the ESW system reflect the ability to utilize ESW pumps associated with Unit 2 power supplies. Specifically, the ESW TS contain special provisions for the piping leading to the Unit 2 portion of the ESW system being isolated within the Unit 1 Protected Area Boundary.
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The proposed changes to the Action statements of the Limiting Condition j
for Operation for the ESW system reflect two-unit operation of LGS 1
including the operability of the Unit 2 emergency diesel ger.erators which will power the 'C' and 'D' ESW pumps.
In addition, the operability of the Unit 2 emergency diesel generators and the connection of the Unit 1 and Unit 2 piping will relieve operating restrictions that currently exist due to the interconnection with a unit under construction. The ESW pumps each have sufficient capacity to supply cooling water to four emergency diesel generators and the associated cooling loads required for safe shutdown for both units.
j The proposed changes to the TS add an Action statement that will ensure that plant operators recognize the interdependency to Unit 2 emergency i
diesel generators. This addition will ensure that sufficient margin of I
safety is maintained when an ESW Action statement is entered and is j
acceptable.
Action a.1 of LC0 S.7.1.1 proposes to reduce the allowed outage time (A0T) for the C or D RHRSW pump. This is consistent with the A and B RHRSW pump and with the proposed Limerick Unit 2 Technical Specifications for the C l
and D pumps. This change is conservative and is therefore acceptable.
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i Actf~on a.2 of LC0 3.7.1.1 proposes to increase the allowed outage time for RHRSW pumps A and B from 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to 7 days (see existing Action a.3 for this condition). The existing Action's A0T of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is based on 3
the fact that the C and D RHRSW pumps' back up power supply (i.e.,
i Limerick Unit 2 EDGs) are not operable due to the ongoing Unit 2 construction. Therefore, during a loss-of-offiste-power event with the A j
and B RHRSW pumps inoperable, there would be no RHRSW system. This is consistent with other designs which allow an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> A0T. With the completion of the two unit design and the operability of Unit 2 EDGs, the C and D RHRSW are fully capable of supplying the required safety related function in any design basis event with concurrent loss of offsite power, even with A and B RHRSW pumps inoperable. Similarly designed systems 1
have been previously reviewed and found acceptable on other dockets (including the Standard Technical Specifications) to iustify an allowed outage time of 7 days. This discussion is valid for any combination of a single RHRSW pump in one loop inoperable concurrent with either RHRSW pump on the other loop inoperable. Therefore this proposed Action is acceptable and will not adversely affect safety.
New Actions a.5, a.6 and a.7 of LC0 3.7.1.1 provide allowed outage times for various combinations of inoperable RHRSW pumps and/or EDGs that supply back up power to RHRSW pumps. The allowed outage times are based on the capabilities of the remaining operable EDGs and RHRSW pumps to
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respond to an accident and/or loss of offsite power. Action a.5 serves to enforce conservative actions only in the event the Unit 2 EDGs providing backup power to C and D RHRSW are inoperable, because the Limerick Unit 1 Technical Specifications provide ACTS at least as conservative when RHRSW pump (s) and/or Unit 1 EDG(s) are inoperable. This situation, where both EDGs serving C and D RHRSW pumps are inoperable, is identical to the facility design on which the existing Unit 1 specifications are based ~
that is all four RHR$W pumps operable and no credit for the Unit 2 EDLs being operable. The existing Unit 1 Technical Specifications allow continuous operation with no restrictions. The proposed Action a.5 is conservative by requiring this condition be limited to 30 days. To maintain the flexibility to change Unit 1 Operational Conditions, such as during unit startup, the exception to Specification 3.0.4 is also provided in this Action. Because this new Action represents more restrictive operation of Unit I with inoperable equipment, the change will not adversely affect safety and is therefore acceptable. Actions a.6 and a.7 similarly serve to enforce conservative actions only with specific combinations of EDGs and RHRSW pumps inoperable. In each case, the new Action is conservative, being more restrictive, or equivalent to the currently approved Unit 1 Technical Specifications or action as evaluated in the previous paragraph, will not adversely affect safety, and, therefore, is acceptable.
The deletion of 4.7.1.1.b will eliminate the declaring of an RHRSW subsystem inoperable in the event the isolation function, which occurs on a process high radiation ~ signal, is not operable. LCO 3.3.7.11 and Table 3.3.7.11-1 Action 101 provides appropriate requirements to address these radiation monitors. These monitors were the subject of an NRC Safety Evaluation Report (SER)' dated August 7, 1987. This SER acknowledged there was no NRC or regulatory requirement to have automatic isolation of the RHRSW system. The automatic termination of RHRSW flow on high radioactivity is not necessary to mitigate the consequences of a design basis accident, or to maintain offsite doses within prescribed limits, since the flow is essentially within a closed system. Sufficient time is available for operator action to manually stop flow if appropriate.
It is therefore inappropriate to declare an RHRSW subsystem inoperable and subsequently require a unit shutdown when the inline RHRSW radiation monitor is inoperable. Since LC0 3.3.7.11 adequately addresses this monitor's function, the deletion of surveillance 4.7.1.1.b will not adversely affect safety and is acceptable.
For the ESW system, proposed Actions a.4 and a.5, and associated footnote of LCO 3.7.1.2, provide A0Ts for various combinations of inoperable ESW pumps and/or EDGs which supply backup power to ESW components. The allowed outage times are based on the capabilities of the remaining operable ESW pumps and the EDGs to respond to an accident and/or loss-of-offsite-power. These Actions serve to enforce conservative actions only with specific combinations of inoperable components. Some combinations have other ESW (LC0 3.7.1.2) or EDG (LCO 3.8.1.1) Actions
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for limited acceptable safe operation.
In each case where the new Actions E
are more conservative than existing Actions, this represents additional restrictions and therefore will not adversely affect safety. Thus, the changes are acceptable.
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' Existing Action c in LCO 3.7.1.2 was required'during Limerick Unit 2
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construction. The Unit 2 ESW system is now available.for interconnection with Unit'1 as designed and described in the Limerick FSAR. Consistent with these.other changes to reflect the common system function of ESW for both Unit 1-and Unit 2, this Action is being deleted. Since this design
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has been previously reviewed and found acceptable'in NRC SER of August
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' 1983, this change will have no adverse affect on safety and is acceptable.
q Normally it is preferred to perform ESW testing of 4.7.1.2.b during l
shutdown conditions when only one of the redundant loops is typically required to be operable.- In the Limerick design with two units sharing this cormnon system this leads to an impractical situation of requiring both units to be shutdown for surveillance testing.
In the event ESW is l
. rendered inoperable during this testing while one or both units are operating, its associated. Technical Specification Actions provide appropriate restrictions and compensatory measures to be taken. These Actions allow required ESW testing to be performed during unit operation while providing acceptable limitations such that there is no adverse affect on safety. Thus,'the' changes are acceptable.
For Limerick Unit 2,.the draft TS submittal by the applicant was similar to that proposed in the application, which is the subject of this safety evaluation. Both the original draft TS for Unit 2 and the proposed TS submitted for Unit 1 listed requirements separately for the RHRSW pumps, the ESW pumps and the supporting diesel generators. During review of.the draft TS for Unit 2, it was the staff's position that the requirements should be expressed in terms of RHRSW/ diesel generator pairs and ESW pump / diesel generator pairs.
For the Final Draft Unit 2 TS a note was added to the ACTIONS in Section 3.7.1.1 that:
"A RHRSW pump / diesel generator pair consists of a RHRSW pump and its associated diesel generator.
If either a RHRSW pump or its associated diesel generator becomes inoperable, then the RHRSW pump / diesel generator pair is inoperable." A similar note was added to the_ ACTIONS in Section 3.7.1.2 of the Final Draft Unit 2 TS that stated:- "An ESW pump / diesel generator pair consists of an ESW pump and its associated diesel generator.
If either an ESW pump or its associated diesel generator becomes inoperable, then the ESW pump / diesel generator pair is inoperable".
The Final Draft TS for Unit 2 is formatted in terms of these pump / diesel generator pairs.
It has been the staff's position that for a two unit facility; there should be one set of TS for both units or the TS, if separate, should be identical. This is particularly important at Limerick where there is a common control room, where the operators are
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qualified for both units and are rotated between Units and where there are common systems such as the RHRSW and ESW with cross unit power supplies. The staff proposed that the TS which are addressed herein be reformatted to be the same as those developed for Final Draft Unit 2 TS.
The licensee agreed to the revisions during a meeting on June 5, 1979.
The TS being issued by this Amendment are revised in terms of wording but not intent from those in the licensee's application. The staff has reviewed the No Significant Hazards Consideration Notice (which was written with the expectation that there might be changes in format and j
wording) and has determined that the Notice fully describes and envelopes
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the revisions the staff has proposed in the TS submitted by the licensee and the initial determination was not affected. The specific changes
- proposed by the staff and accepted by the licensee are:
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a)
The title at the top pages 3/4 7-1 now reads " Residual Heat Removal Service Water System." The title at the top of page 3/4 7-3 reads
" Emergency Service Water System." After each title the staff proposed to add "-Common System" to clearly alert the operators that there is an interdependency between units. These changes also require a revision to the Index on pages xiii and xxi.
b) renumbering various Actions to be consistent with other Action deletions and additions c) combining and. rewording Actions d) updating Bases Jr these systems i
These changes are primarily administrative and editorial changes made for clarity. These revisions provide no change in technical centent or intent of the specification;s proposed by the licensee and no red 4ction in the margin of safety. Thus, the changes are acceptable.
4.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change to a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes to the surveillance requirements. The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the
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types, of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement nor environmental assessment need be prepared in connection with the issuance of this amendment.
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5.0 CONCLUSION
The Commission made a proposed determination that the amendment involves no significant hazards consideration, which was published in the Federal Register (54 FR 18953) on May 3, 1989 and consulted with the State of Pennsylvania. No public comments were received and the State of Pennsylvania had no comments.
The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable asscrance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and the security nor to the health and safety of the public.
Principal Contributors: Dick Clark, Raj Anand, Om Chopra Dated: June 20, 1989
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