ML20207P539
| ML20207P539 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 01/13/1987 |
| From: | Gallagher J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | |
| Shared Package | |
| ML20207P540 | List: |
| References | |
| NUDOCS 8701160228 | |
| Download: ML20207P539 (21) | |
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~~ ~4 e-BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of Docket No. 50-352 PHILADELPHIA ELECTRIC COMPANY APPLICATION FOR AMENDMENT OF FACILITY OPERATING LICENSE NPF-39 Edward G. Bauer, Jr.
Eugene J. Bradley 2301 Market Street Philadelphia, Pennsylvania 19101 Attorneys for Philadelphia Electric Company
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0701160228 870113 PDR ADOCK 05000352 p
o BEFORE THE.
UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of Docket No. 50-352.
PHILADELPHIA ELECTRIC COMFAhi APPLICATION FOR AMENDMENT OF FACILITY OPERATING LICENSE NPF-39 Philadelphia Electric Company, Licensee under Facility Operating License NPF-39 for Limerick Generating Station Unit 1, hereby requests that the Technical Specifications contained in Appendix A of the Operating License be amended as indicated by a vertical bar in the margin of the attached pages 3/4 3-14, 3/4 3-
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5 15, 3/4 3-16, 3/4 3-21, 3/4 3-22, 3/4 3-25, 3/4 3-26, 3/4 3-30, 3/4 3-31, 3/4 6-22, 3/4 6-26, 3/4 6-43, 3/4 6-46, 3/4 6-47, 3/4 6-49, 3/4 6-50, 3/4 6-51, 3/4 6-53, 3/4 6-54 and B3/4 6-5.
In addition, Licensee requests the addition of new pages 3/4 i-51a and B 3/4 6-Sa to allow for additional material. -
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Licensee is requesting these changes in order to c
implement plant modifications to meet Condition 2(c)(14) of Operating License NPF-39, which requires the connection of the
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refueling floor volume to the Standby Gas Treatment System (SGTS) prior to any movement of irradiated fuel.
The proposed changes concern those areas of the Technical Specifications which a'ddress the SGTS system capacity, isolation actuations, testing and footnotes which will become obsolete upon completion of thet modification discussed herein.
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Discussion The design objective of the Standby Gas Treatment System was to provide a common system to serve both Unit 1 and Unit 2 reactor enclosures and the common refueling area.
Included in the original design were provisions for internal air recirculation, filtering, and mixing during the secondary containment isolation operating mode via the Reactor Enclosure Recirculation System (RERS).
Each of the units' RERS was designed to mix the air within its respective reactor enclosure containment zone or refueling area (or both simultaneously) depending on the combination of isolation signals present.
The
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SGTS consisted of a common set of exhaust filters and fans with duct connection downstream of the RERS fans in both reactor enclosures.
The SGTS fan capacity of 3000 cfm was sufficient to maintain all three isolated secondary containment zones (U-1, U-2 and refueling area) at a negative differential pressure r
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t Laimultaneously.
However, several circumstances led to the 1
current arrangement by which the SGTS is aligned only to the Unit l
i 1 reactor enclosure.,
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Subsequent to the original design, the NRC adopted a new guideline,.CSB 6-3, which evaluated the performance of the i
standby gas treatment system to mitigate post design basis accident (dba) offsite radiological releases in terms of
" drawdown time".
The impact of drawdown time as a parameter on the Limerick SGTS posed several problems.
A postulated failure of the non-safety grade spent fuel pool cooling system would prolong drawdown times due to evaporation from the fuel pool along with the associated increased heat loads.
Further, the drawdown time was found to be unacceptable when the Reactor Enclosure air infiltration rate input parameters were increased to 100%.of the building free-volume per day from the previously utilized 50%.
In addition, it was determined that the potential intermixing of the refueling area and reactor enclosure atmospheres via the RERS was environmentally unacceptable for some equipment within the Reactor Enclosure due to the impact of high humidity caused by the evaporation from the spent fuel pool during postulated loss of pool cooling.
In order to remedy this condition, the refueling area volume was isolated from the RERS; however, this action resulted in disconnecting the refueling area from SGTS.
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9 As a result of these conditions, the standby gas
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treatment system will be modified to directly connect the SGTS to the refueling area and replace the existing fans with fans of l
higher capacity.
The new fans and common ductwork are sized for 8400 cfm to enable meeting the present drawdown time limitation with the simultaneous connection of all three secondary containment zones (Unit 1 reactor enclosure, Unit 2 reactor enclosure (future), and common refueling area).
The direct connection of the refueling area to the SGTS eliminates the evaporative heat loading and environmental concerns that were present when the refueling area atmosphere had the potential to mix with the reactor enclosure atmosphere via the RERS.
These modifications require changes to the Technical Specifications to:
- 1) reflect new system capacity; 2) address new system configuration; 3) address new isolation actuations; and 4) remove footnotes which are obsolete upon completion of the modifications.
Description of Changes to Technical Specifications (TS)
As a result of the modification, several changes to the TS are necessitated.
In addition, during the review of the affected TS section, several minor inconsistencies were identified which are also included in this amendment request.
The changes requested to page 3/4 3-14, 3/4 3-21, 3/4 3-25 and 3/4 3-30 delete isolation signals upon Refueling Area Ventilation Exhaust Duct Radiation High and Outside Atmosphere to r
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'efueling Area Differential Pressure Low from the Primary R
Containment Isolation sections of the affected tables.
Although these signals actuate,certain primary containment isolation valves in Table 3.6.3-1, this change is requested to prevent confusion among the operators with the same signals which appear in the Secondary Containment Isolation sections of the affected tables.
To reflect the fact that these signals wil still actuate primary containment isolation valves, footnote (a) is added to the " Isolation Signal" column heading on page 3/4 3-15, I
as well as a clarification to notes (a) and (c) on page 3/4 3-16.
(t Additional changes requested on page 3/4 3-15, 3/4 3-22, 3/4 3-26 and 3/4 3-31 revise the manual initiation isolation signal to be either from the Reactor Enclosure or the Relueling Area upon completion of the modifications.
The changes requested to page 3/4 3-16, 3/4 6-22, and 3/4 6-26 add the refueling area high radiation and low differential pressure isolation signals (designated as R and T) which become functional upon completion of the modifications.
In conjunction with these changes, Note 25 on page 3/4 6-43 has been deleted and references to Note 25 for the drywell purge and suppression pool purge valves on pages 3/4 6-22 and 3/4 6-26 will t
t be deleted because they become obsolete upon completion of the modifications.
Also, note 33 is added to 3/4 6-43 and references to it are added for the Large Volume Purge Exhaust Valves on pages 3/4 6-22 and 3/4 6-26 to reinforce the fact that these are both primary containment and refueling floor secondary containment isolation valves. i
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The changes requested to page 3/4 6-49 and 3/4 6-51 delete footnotes which become obsolete upon completion of the modifications and add the refueling area high radiation and low 5
differential pressure isolation signals to the Drywell Purge Exhaust Valves.
Further, page 3/4 6-51 is being changed to correct an error in the heading (Refueling Area was erroneously titled Reactor Enclosure) and to add the drywell purge exhaust and suppression pool purge exhaust isolation valves as part of
' the Refueling Area Secondary Containment Automatic Isolation Valves table.
Upon completion of the modifications, it will be necessary to perform surveillances on the system.
In order to provide definition of the testing, the surveillance requirements on page 3/4 6-53 are changed, including the associated footnote, to reflect the new design and capacities.
In addition, a new surveillance requirement is added on page 3/4 6-54 which addresses the multiplicity of the system.
Additionally, pages 3/4 6-46, 3/4 6-47 and 3/4 6-50 are changed to reflect the slide gate dampers which are being added as part of the modifications.
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The last page for which a change is requested is page B3/4 6-5.
This page is being revised to reflect the new system design and to clarify the surveillance requirements and criteria for the new system, i
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Safety Discussion The modifica.tions meet all of the applicable original design requirements which include, but are not limited to, seismic and environmental qualification, separation criteria, quality assurance, and testability and independence of redundant channels.
In making this determination, the following FSAR sections and NRC questions were reviewed:
FSAR Sections 3.2; 6.2.3; 6.2.4; 6.3; 6.5.1.1; 7.1; 7.3.1.'l; 7.3.2.7; 7.5; 8.3; 9.3; 9.4.2.1; 11.5; 15.6; 15.7.4; NRC questions 460.4 and 460.23.
The new fans will be installed in approximately the same location as the existing fans which were evaluated for missile hazard protection.
Missiles from rotating parts, therefore, will not affect safe shutdown capability.
The majority of the installation work can be made without affecting the existing SGTS.
The existing and new connecting duct work, with the addition of stiffeners, will meet all necessary criteria to withstand the higher operating pressures resulting from the increased fan size.
No physical changes are required to the existing SGTS heaters, High Efficiency Particulate Air (HEPA) or charcoal filters because this equipment was originally designed for the operation of the drywell purge system at a flow rate of 11,000 cfm.
The increased SGTS flow rate will reduce the residence time in the existing 8-inch deep charcoal filter bed from approximately 1.3 seconds to approximately 0.5 seconds.
Although C
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ithe increase in SGTS flow rate from 3000'to 8400 cfm, along with the resulting decreased. residence time from 1.3'to 0.5 seconds, will not meet the NRC design guidelines given in Regulatory Guide 1.52 Position C.3.1, which requires an average residence time of 0.25 sec for each two-inches of adsorbent bed, the Limerick charcoal filters will still meet or exceed the NRC testing
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criteria for assigning a 99% filter efficiency at the new i
operating conditions as a result of the present bed depth of
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eight inches.
Table 2 of RG 1.52 assigns a 99% efficiency for activated carbon bed depths of 4-inches or greater.
Additionally, ERDA 76-21 Section 3.4.2 states, "For constant gas residence time, efficiency (of a filter) also increase with increasing velocity".
Therefore, an 8-inch deep charcoal filter with an approximate 0.5 second residence time is more efficient i
i than a 4-inch deep filter with the same residence time due to the additional 4-inches of charcoal bed depth which are available for adsorption.
Therefore, the Limerick SGTS filters are capable of satisfying the efficiency requirements specified in Table 2 of R.G.
1.52 for bed depths of 4-inches or greater at the higher air velocity and will provide the necessary removal capability.
i It should be noted that the 8400 cfm flowrate will occur l
only during the drawdown period, during which no credit is given for filtration.
Only after drawdown is filtration credit given.
The post drawdown flowrate is equivalent to the in-leakage of the f
isolated zone or zones.
A three-zone isolation will have a i
maximum in-leakage flowrate of 3264 cfm.
At this flowrate the residence time in the existing 8-inch deep charccal filter will 1
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I be approximately 1.1 seconds.
This residence time meets the NRC i
design guidelines given in Regulatory Guide 1.52, Position C.3.1.
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I New prefilte'rs will be included in the modification to I
the refueling area SGTS exhaust duct, installed upstream of the SGTS filters, which will extend the life of the existing SGTS HEPA filters.
These filters will serve a prefiltering function similar to that provided by the RERS filters whenever toe Reactor
' Enclosure is isolated.
A new SGTS exhaust duct will be connected to the refueling area by way of two new fail-open valves.
Since this duct must be connected to the common SGTS, which also serves the reactor enclosure, a vent off the RERS fan discharge must be added to reduce the back-pressure and allow the drawdown of the refueling area.
The vent will be balanced tc provide sufficient air flow to the SGTS duct to ensure double filtration after RERS fan operation is initiated.
Since the RERS fans do not start until 3 minutes post-LOCA due to electric load sequencing design, the vent introduces a 3-minute time period when RERS prefiltration is not available.
This change to the system design will not significantly affect SGTS HEPA filter life because of I
the short period of time RERS prefiltration is not available.
As discussed in FSAR Table 15.6-13, the FSAR post-LOCA offsite doses are conservatively based on a drawdown time of approximately 5 minutes rather than the actual drawdown time of 2.25 minutes.
During this 5-minute period, all containment releases are assumed to directly exfiltrate to the environment without any filtration.
Therefore, the loss of double filtration originally provided by
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the RFRS filters during the first 3 minutes of SGTS operation h
will have no effect on the offsite doses previously evaluated in FSAR Section 15.6.5.,
j In.the Safety Evaluation Report (SER) Supplement 3, Table 15.5, the SER post-LOCA offsite doses are based on an SGTS filter efficiency of 99/99/99 percent for elemental, organic and particulate iodine, respectively.
These assigned decontamination efficiencies are based on Regulatory Guide acceptance criteria for adsorber bed depths of 4-inches or more with HEPA filtration.
The SGTS filters alone without prefiltration meet these decontamination efficiencies.
Since no efficiency credit for prefiltration by RERS filters has been assigned by the NRC for the exhaust flow from the SGTS, the installation of the RERS exhaust vent will have no effect on the offsite doses as evaluated in SER Supplement 3 Section 15.6.
The new SGTS fan control during a multiple zone drawdown will receive a control signal based on the zone with the least pressure differential.. This will ensure that all zones connected to the SGTS will have at least a negative 0.25 inches of water gauge differential.
i Slide gate dampers will be added to isolate each zone from the SGTS in the event that its secondary containment isolation system is not in service.
This will prevent any valve failures from connecting the SGTS to an area which cannot be drawn down.
These slide gate dampers will have external position switches to block any isolation signals to the SGTS fans while f
7 the' damper is closed.
Slide gate dampers will also be added to the drywell and suppression pool exhaust ducts to maintain SGTS operability while servicing various primary containment
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atmospheric control isolation valves.
Upon completion of the modifications, isolation signals R (Refueling Area Ventilation Exhaust Duct-Radiation-High) and T (Outside Atmosphere to Refueling Area Differential Pressure-Low) become fully functional.
As appropriate, these signals have been added to the isolation valve tables.
In addition, the Primary j
i Containment Isolation sections of Table 3.3.2-1, 3.3.2-2, 3.3.2-3 and 4.3.2.1-1 are revised to delete references to these signals.
It appears that the inclusion of these isolation signals was an oversight during the development of the Technical Specifications and is not reflective of the Limerick design in which the refueling Area constitutes a distinct zone of secondary containment that does not communicate with the Reactor Enclosure secondary containment.
Since Technical Specification 3.6.5.1.2 requires operability of the refueling area secondary containment integrity (and hence these isolation signals) under Operational Condition *, a complex crcss-reference of operational conditions would be required to allow signals R and T to remain under the f
Primary Containment Isolation section of these tables.
Therefore, deletion of the cross-reference will avoid potential confusion among the operators.
Isolation signal R will remain on the primary containment isolation valves currently designated in Table 3.6.3-1 and isolation signals R and T will be added to the valves [
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presently indicated by Note 25 of. Table 3.6.3-1 as a part of this modification.
Instrumentation associated with these isolation signals _will-be itemi, zed in._the Secondary Containment Isolation sections of Tables-3.3.2-1, 3.3.2-2, 3.3.2-3 and 4.3.2.1-1.
Footnote'(a),will be added to the " Isolation Signal" column heading of Section 7.0 of Table 3.3.2-1 to acknowledge that these signals may also operate primary containment isolation valves.
The cumulative effect of all these changes upon the primary containment isolation-system will be to delete requirements for
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operability and surveillance testing of these instrument channels (and hence closure of the affected containment isolation valves) under Operational Conditions 1, 2 and 3, and to substitute these requirements only under Operational Condition *.
This is consistent with Technical Specification 3.6.5.1.2 operability requirements for'the Refueling Area secondary containment integrity, since the HVAC system must be operating in order for the instrument sensors to produce meaningful output signals.
This change will not impact any primary containment isolation decign requirements.
The affected containment isolation valves would continue to be closed by at least one of the following isolation signals which continue to be required in Operational Condition 1, 2, or 3 :
1.
Reactor Vessel Low Water Level (Level 2) 2.
High Drywell Pressure 3.
High Radiation in the Reactor Enclosure r
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In additiori, the primary containment purge and vent valves would still be isolated upon a low differential pressure signal between the outside atmosphere and the reactor enclosure and the large diameter purge and vent valves would be isolated by a high radiation signal in the North Stack.
The design meets the redundancy and diversity requirements of SRP 6.2.4 as described in FSAR Section 6.2.4 and Table 6.2-17 and also meets the requirements of NUREG-0737 item II.E.4.2 as discussed in FSAR Section 1.13.2.
The electrical cont rol circuitry and active components of this modification are designed to meet the single active failure criterion.
The fans will be powered from existing Motor Control Centers (MCCs).
Conclusion The new SGTS fans, dampers, controls and ductwork will l
be fabricated and installed under a QA program which meets or exceeds the original requirements.
This ensures there will not be any increase in the probability of equipment failure.
All active components will have redundancy and electrical separation to maintain the same level of system availability to mitigate an accident considering the malfunction of a single piece of equipment.
Each channel fails in a safe position on loss of l
power to allow operation of its redundant channel if required.
Each SGTS channel will be functionally tested verifying correct system operation before being placed in service. t
- The SGTS HEPA filters and charcoal adsorbers will provide a 99% decontamination efficiency even while operating at the new higher flow rate of 8400 cfm.
Limerick's 8-inch deep SGTS charcoal adsorber will provide an approximate 0.5 second residence time at 8400 cfm.
This design will exceed the efficiency of a 4-inch deep charcoal adsorber with the same residence time because of the additional four inches of bed depth.
Thus, an SGTS charcoal adsorber decontamination efficiency of 99% based on RG 1.52 is justified at the higher flow rate.
The SGTS HEPA filter banks may be operated at flow rates of up to 11,000 cfm without exceeding their rated capacity.
The current-Technical Specification required drawdown time of 121 seconds will be maintained since the new fan capacity will provide a minimum of 2800 cfm of flow from each reactor enclosure.
The electrical loads for the modifications associated with increasing the SGTS fan capacity and connection to the refueling area can be accommodated by the existing diesel generators.
The addition of new starters to the motor control centers will not adversely affect the seismic response of the existing MCCs.
There is no effect on the bus loading associated with this portion of the modification work.
The new duct work does not penetrate any fire barriers.
The combustible loading analysis is not affected because this modification does not require any new cable trays to be installed, and the new cables which are added in existing cable trays do not exceed the maximum allowable fill level used in the original analysis.. ___. --
The proposed changes to the Technical Specifications are necessary to incorporate these modifications into the plant design.
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Significant Hazards Determination The NRC has provided guidance covering the application of the standards for determining whether a significant hazards consideration exists by providing certain examples (51 FR 7751) of amendments that are considered not likely to involve significant hazards consideration.
Several of these examples are appropriate for the requested changes.
Examples (i)
"A purely administrative change to the Technical Specifications..." and (ii) "A change that constitutes an additional limitation restriction or control not presently included in the Technical Specifications..." envelope the changes discussed in this amendment request.
However, because the changes are reflective of a system modification, the modifications discussed above and the necessary Technical Specification changes requested herein compare best to example (ix) which relates to (1) the repair or replacement process involving practices which have been i
successfully implemented at least once on similar components or
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f systems, and (2) the repair or replacement of a major component or system important to safety that does not involve a significant increase in the probability or consequences of an accident
'e previously evaluated or create the possibility of a new or different kind of accident from any accident previously evaluated and does not result in a significant change in its safety 3
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f function or a significant reduction in any safety limit i
h associated with the system.
This propose'd change does not involve a significant hazards consideration because:
(1)
It does not involve.a significant increase in the probability or consequences of an accident previously evaluated in the FSAR.
The new equipment and ductwork will be installed in j
accordance with an approved QA program which meets or exceeds the original installation requirements.
Additionally, the new SGTS equipment will be tested in accordance with written procedures that meet or exceed the original testing requirements.
This ensures that the new SGTS will be installed in a manner which meets all of the original SGTS safety requiraments.
The new equipment is fabricated in accordance with an approved QA program which meets or exceeds the original fabrication requirements.
All active components have redundancy and electrical separation which maintains the l
level of capability to mitigate an accident considering a single equipment malfunction.
Each SGTS channel will be tested to verify proper operation prior to being placed in service.
The SGTS does not have any failure modes which would increase the probability of an accident because it operates in response to both reactor t
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enclosure and refueling area secondary containment isolation signals.
The new SGTS will maintain the same high degree of reliability as the original system to r
mitigate a LOCA or fuel handling accident.
No changes to the surveillance testing requirements are proposed except to incorporate these new values, add additional requirements and/or provide clarification.
(2)
It does not create the possibility of a new or different kind of accident from any accident previously evaluated in the FSAR.
I The new system will operate in a similar manner to the original SGTS.
The refueling area ductwork will have two isolation valves installed in parallel to meet the single active failure criterion.
Pressure differential control circuitry will maintain a negative 0.25 In. W.G.
in the isolated zone (s).
Logic changes will be made to automatically isolate any zone connected to the SGTS in order to prevent a spurious failure of an isolation valve from connecting the SGTS to a zone which cannot be brought under SGTS pressure control.
Slide gate dampers i
are provided to manually isolate any zone from the SGTS.
j The changes as discussed above will extend the SGTS operation to the refueling area and Unit 2 Reactor Enclosure without creating the possibility of an accident or malfunction different than previously evaluated.
The requested changes to the Technical i
Specification merely acknowledge the new design and delete obsoleted footnotes.
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(3)
It does not involve a significant reduction in margin of safety.
The SGTS HEPA filters and charcoal adsorbers will maintain the 99% decontamination efficiency per Regulatory Guide 1.52 at the higher flow rate of 8400 cfm.
The existing 8-inch deep bed will provide an approximate 0.5 second residence time at 8400 cfm.
Reg.
Guide 1.52 assigns a 99% efficiency to 4-!nch bed depths with 0.5 second residence time.
The new design will exceed the efficiency of a 4-inch deep bed with the same residence time because of the additional four inches of bed depth.
The SGTS HEPA filters were originally designed for operating at flows up to 11,000 cfm without exceeding their rated capacity.
The Technical Specification drawdown requirement of 121 seconds will be maintained since the new fan capacity will provide the minimum 2800 cfm flow needed to meet the requirements.
The proposed changes to the Technical Specifications which are requested as a result of these modifications do not decrease the margin of safety because no requirements are deleted but rather requirements are added and values are changed to represent the new design.
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Therefore, based on the above considerations, this modification and the requested changes to the Technical Specifications do not involve a significant hazards consideration.
Environmental Consideration These modifications and the associated changes to the Technical Specifications will not result in any increase in the amount, or result in any changes in the types of any effluent which may be released off-site, and there is no significant increase in individual occupational radiation exposures.
The Plant Operations Review Committee and the Nuclear Review Board have reviewed these proposed changes to the Technical Specifications and have concluded that they do not involve unreviewed safety questions or involve Significant
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Hazards Considerations and will not endanger the health and safety of the public.
Respectfully Submitted PHILADELPHIA ELECTRIC COMPANY By N
LVice Presidebt
COMMONWEALTH OF PENNSYLVANIA a
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COUNTY OF PHILADELPHIA J. W. Gallagher, 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 Licenses and knows the
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contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.
1 hM u
o subscribed and sworn to P-before me this O day of }
,A Notary Public MELANIE R. CAMPANELLA Notary Public. Philadelphia, Phifadelphla Co, My Commission b; ires Febrwy 12.1930 l
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