ML20199A600

Provides Response to NRC RAI Concerning Lgs,Units 1 & 2,TS Change Request 93-28-0.W/four Oversize Drawings

ML20199A600
Person / Time
Site:	Limerick
Issue date:	11/10/1997
From:	Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20199A607	List: ML20199A600 ML20266C291 ML20266C296 ML20266C300
References
NUDOCS 9711180032
Download: ML20199A600 (7)

Text

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, .- Statlee Support Depettment

. -L8$ rut PECO NUCLEAR esco t% cm A Unit of PECO Enugy - wIyDNomN November 10,1997 Docket Nos. 50-352 50-353 Ucense Nos. NPF-39 NPF-85 U.S. Nuclear Regulatory Commission Attention: DocumentControlDesk

- Washington DC 20555 Subject Limerick Generating Station, Units 1 and 2 Technical Specifications Change Request No. 93-28-0 Response to Request for Additional information

Dear NRC Officials:

This letter is being submitted in response to the NRC's request for adtlitional information conceming Limerick Generating Station (LGS), Units 1 and 2, Technical Specifications (TS)

Change Request No. 93-28-0. PECO Energy submitted TS Change ( .equest No. 93-28-0 by letter dated May 3,1996, requesting that the TS of Operating License Nos. NPF-39 and NPF-35 for LGS, Units 1 and 2, respectively, be amended to change TS Surveillance Rcquirements 4.6 5.3.a and 4.6.5.4.a for flow testing cf the Standby Gas Treatment and y Roactor Enclosure Recirculation Systems from monthly to quarterly.

Subsequently, during a telephone conversation between PECO Energy and NRC represeritatives on September 24,1997, the NRC requested that we provide additional information regarding this submittal. This additionalinformation is being submitted under affirmation, and the required affidavit is enclosed.

The following information is be!ng supplied in response to the seven questions asked by the NRC representatives.

1. Provide more detailed information about the SGTS and RERS vertical charcoal adsorber beds in addition to the Information provided in the UFSAR, including a hN detailed drawing or picture.

Ans. Stondby Gas Treatment System (SGTS)

Each SGTS filter train consists of an electric heater, ar upstream HEPA filter, a charcoal adsorber, and a downstream HEPA filter. The charcoal adsorber is an 8-inch deep vertical gasketless and seam-welded bed containing approximately 2400 pounds of activated, impregnated charcoal. The charcoal adsorber is capable of removing not less than 99.0% of elementallodine and 99.0% of methyliodide at 70% relative

- humidity. See Attachnient 1 for vendor drawing. The maximurn loading is 2.5 milligrams of iodine per gram of activated charcoal.

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Reactor Enclosure Recirculation System (RERS) ,

Each RERS filter train consists of a profitter, en upstream HEPA filter, a charcoal j i adsorber, and a downstream HEPA filter. The charcoal adsorber is a 2-inch deep

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vertical gasketless and seam-welded bed containing approximately 13,000 pounds of -

activated impregnated charcoal.' The charcoal adsorber is capable of removing not less

[ than 95.0% of elemental iodine and 95.0% of methyllodide at 70% relative humidity. -t

- See Attachment 2 for vendor drawing.

2. _ Provide more information about how the Instrument Air (IA) supplies air to the :  !

charcoalin addition to the UFSAR. t Ans. The SGTS and RERS have been designed to continuously purge the charcoal adsorbers with 1 cfm of dry instrument air to maintain moisture levels at a minimum L whenever the systems are not la use.

s' Safety-related solenoid valves are used to provide dry instrument air (IA) to the~  :

e 1 upstream side of the charcoal adsorbers. Whenever the filter systems are not in use, the associated solenoid valve is energized to allow a continuous purge of the charcoal adsorbers. Upon system operation; the_ associated solenoid valve is doenergized and

- the continuous purge air is sitopped. See Attachment 3 for the schematic drawing and P&lD associated with the SGTS solenoid valve. These drawings are typical of the -

function for the RERS purge air solenoid valves.

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3. Is the tA system periodically tested to ensure high quality IA as specified in ANSI /ISA S-7.3 (or ANSI MC11.1)? -

Ans. Yes." Limerick's instrument air (IA) is tested to ensure a high quality on a regular basis (overy refueling outage) per the requirements of ANSI /ISA S-7.3 and as specified in the PECO Energy response to Generic Letter No. 88-14 dated February 13,1989.

4. Is there a TS requirement for the lA function to purge SGTS and RERS charcoal?

! Ans. No. There is no Technical Specifications requirement for the instrument air purge of -

the SGTS and RERS charcoal adsorbers. However, there is a commitment in the LGS Updated Final Safety Analysis Report (UFSAR) for purging tb SGTS and RERS

. charcoal adsorbers with dry instrument air as well as a discussion in the Technical Specifications Bases (paragraph 3/4.6.5) relative to the purging feature. See Attachment 4 for the UFSAR pages.

5. How long are the 4.6.5.3a tests currently performed? Most plants with heaters run the system for 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> with the heaters on.

, Ans.- The monthly flow tests of the SGTS and RERS typically take less than one hour to .

perform. This is sufficient time to verify that flow has been established in the system as required. When the test is performed on each isolation channel, a complete secondary ~

containmentisolation occurs. ,

- Running the system with heaters on for 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> is a requirement of Regulatory

Guide 1.52, Revision 2. ; However, PECO Energy had previously taken exception to this requirement as discussed in Table 6.5-2 of the LGS UFSAR based on our design >

= feature of a continuous air purgs.

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4. Submittal states that the currently specified test frequency results in the SGTS >

being run at least twice per month or as many as eight times per quarter. Isn't it -

possible for each train of the SGTS to only run once a month because the SGTS -

has two fully redundant trains that can handle the flow from one train of the Unit i RERS and one train of the Unit 2 RERS simultaneously?

Ans. Yes.- It is possible to run only one train of SGTS once a month if the test is performed with one tesin of Unit 1 RERS and one train of Unit 2 RERS simultaneously. However, simultaneously o wrating a train of RERS from each unit does not explicitly satisfy the current Technica Specifications surveillance which requires testing at the subsystem

- level. Additionally, this configuration of testing would also: (1) increase the level of ~

c.omplexity by initiating a dual unit engineered safety feature actuation; (2) challenge the station's manpower resources due to the combined inspections, as well as increasing the test time; and (3) challenge the operation of both running units due to the rising building temperatures resulting from shutting off of the normal HVAC systems and the increased test time. Based on the above, it is our position that to perform the -

- monthly flow testing as described above, it is not practical norjustified and would not reduce the unnecessary wear and tear on the system components.

7. ' Submittal states that the lesk-tightness of the SGTS and RERS is verified by

inplace penetration and bypass leakage testing. These tests do not measure leak-tightness; they only measure bypass around the filters. A tracer gas, technique or a pressure decay technique measure leak-tightness.

Ans. Your comment regarding our submittal is correct in that the test we perform at least once per 24 months is in fact a " bypass leakage" test and not a " leak-tightness" test of SGTS and RERS as stated. The statement sitould read as follows:

"As stated in the LGS TS, the bypass leakage of the SGTS and RERS is verified at least once per 24 months, or (1) after any structure maintenance on the HEPA filter or charcoal adsorber housing, or (2) following painting, fire or chemical release in any ventilation zone communicating with these systems. This verification assures that each system satisfies the in-place penetration and bypass leakage testing acceptance criteria of less than 0.05% and uses the test procedure guidance in Regulatory Positions C.S.a C.S.c. and C.S.d of Regulatory Guide 1.52,

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Revision 2, March 1978."

If you have any questions or require additionalinformation, please contact us.

Very truly yours, -

! fYM .g G. A. Hunger, Jr.

Director- Licensing

Enclosure:

Attachments

! cc: H. J. Miller, Administrator, Region I, USNRC (w/ enclosure / attachments)

, A. L Burritt, USNRC Senior Resident inspector, LGS (w/ enclosure / attachments)

L R. R. Janati, PA Bureau of Radiological Protection (w/ enclosure / attachments) .

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COMMONWEALTH OF PENNSYLVANIA -  :

- SS l COUNTY OF PHILADELPHIA ':

John B. Cotton, 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 response to the Request for Additional information for Technical Specifications Change Request No. 93-28-0, to mod;fy the surveillance interval for flow testing of the Standby Gas Treatment and Reactor Enclosure Recirculation Systems from monthly to quarterly, and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.

M51s u

' ' Vice President Subscribed and sworn to before me this[/M day of 1997.

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Gd&& /

NOTARIAL SEAL CAROL A.WALTON. Notary Pubso Oty of PNiede'pNa. Ptula, county My Cw. 22:lon Expires May 28,2001

l ATTAcWHEAT IV

, LG8 UFSAR P S. ( 0 F 2.

c. *The third temperature setpoint (550*F) actuates an alarm

'in the control room. The operator shall investigate to determine if a fire has occurred and introduce the-fire protection water to the charcoal plenum, if necessary, as followa: The operator manually opens the valves, thus l introducing the fire protection water to the charcoal plenum. A drain valve is provided to drain the water from the filter plenum.

Four test canisters are provided for each char.:oal adsorber. These canisters contain the same depth of the same charcoal that is in the adsorber. The canisters are mounted so that a parallel flow path is created between each canister and the adsorber.  ;

Periodically one of the canisters can be removed and-laboratory tested to verify the adsorbent efficiency.

Permanently inctalled injection and sampling ports are provided for all ESF atmosphere cleanup systems to permit accurate testing in l accordance with ANSI N510. Providing fewer charcoal test canistere on the ESF atmosphere cleanup systems than specified in ANSI N509 (1980) section ' 4.ll results in equal or more frequent replacement of activated ~ carbon. Regulatory Guide 1.52 states that testing of representative samples should be performed (1) initially, (2) at least once per 18 months thereafter for systems in a standby status, or after 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of system operation and (3) following painting, fire, or chemical release in any ventilation zone communicating with the system. However, representative samples of ,

the SGTS are tested at least once per 24 months as discussed in '

Table 6.5-2. More frequent replacement may result because Regulatory Guide 1.52 further states that when no representative samples are available for testing, the activated carbon should be replaced with new activated carbon.

Access doors, with 30y68 inch openings, to each HEPA filter compartment are provided. An 18 inch access hatch is provided fore the charcoal filter compartment.

The HEPA filter and charcoal filter housings are of all-Welded construction.

Interior lights with external light switches are provided in the HEPA filter plenums to facilitate inspection, testing, and ,

replacement of components. l lTlie"SGTS :hasTheen'designedt to? continuously [purgithe7 filter plenumsy MithldryXinstrumentTairlwhenfthe ; filtersFare $hotliniuser Any' amount"of" dry' air" continuously purged'through~the'adsorbers and

-HEPA filters will entrain moicture and maintain moistuta levels at a minimum because the duct-work is gas-tight and there is no internal humidity cource. (The periodic operation of the ESF atmosphere cleanup (SGTS) train could introduce additional moisture l into the system and increase moisture levels above those normally maintained.)

6.5-9 Rev. 06 12/96 l

ATTACMEt4T TV

. . LGS _UFSAR: .

M$kIM[tCairf Mhntuiten hoseVer 7"kny' amount' of" dry' air' continuously "purgediECf TthroughTthEadsorbers.and HEPA filtersrwill entrain moisture and.

maintain moisture levels at= a minimum because the-duct-work is gas- o (The _' periodic

, itight and there is no' internal. humidity - source. I operation ofL the ESF atmosphere _ cleanup train - could introduce 1

. additional ~ moisture-into the system.and increase moisture levels j

-above those normally maintained.)

The RERS is actuated either automatically (safety-related mode): or I manually _ for routine. system operability testing (nonsafety-related mode).~ The automatic _ actuation _ . is originated by ^ the reactor -

enclosure isolation signal (Section 6.5.1.3.1.d) .

The~ automatic or manual actuation re 11ts in a start of a lead fan. .

Associated controls are then activated to- open or modulate-appropriate' dampers'so that the system function is accomplished.

If the'. lead fan- fails - to' operate, the standby fan _ starts 4

automatically and the standby filter train is activated.

6.5'.1.3.3 Design. Evaluation

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The RERS is designed for filtration of contaminated air- in the reactor enclosure following _ a postulated - accident or abnormal occurrence which could result.in abnormally high airborne radiation in the reactor enclosure. Equipment is powered' from Class 1E buses and all oower circuits meet IEEE 279 and IEEE 308 requirements to ensure uninterruptible operation _ in the event of loss of normal of fsite ac power. Redundant components are provided where necessary to ensure that a single failure will not impair' or preclude system operation. The RERS is designed to seismic Category I requirements as discussed in Section 3.7 to ensure that the system remains intact and functional if there is an SSE. Components and materials of the'RERS have been selected to assure availability of the system under postulated' accident conditions. A RERS failure mode and effect analysis =is presented in Table 6.5-6.

q An_ analysis was cond_ucted to calculate the maximum post-LOCA time

! . period for which'the relative humidity at the inlet of the RERS

- charcoal filters could exceed 70%. It was found that within 15 minutes after isolation of the reactor enclosure secondary containment, the relative humidity will decrease from an initial maximum condition of 76.2% to below 70%. The_ following conservative rationale was used for this analysis:

Ia. The - reactor . enclosure- supply air system uses

, unconditioned outdoor air- to provide once-through

, = ventilation to cool the reactor enclosure during normal

. plant, operation.

6.5-17 2

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