ML20112C425
| ML20112C425 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 01/08/1985 |
| From: | Jens W DETROIT EDISON CO. |
| To: | Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| EF2-72039, NUDOCS 8501110185 | |
| Download: ML20112C425 (16) | |
Text
{{#Wiki_filter:. CDyne H. Jens Vem Predet Nuclear Operatens fermL2 6400 North Dme Highway iSOn tatsjs*4isa January 8, 1985 Newport, M chtgan 48166 EF2-72039 Director of Nuclear Reactor Regulation Attention: Mr. B. J. Youngblood, Chief Licensing Branch No. 1 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 20555
Dear Mr. Youngblood:
Reference:
Fermi 2 NRC Docket No. 50-341 ~
Subject:
Clarification of Positiota on Silicone Duct Sealant and Other Issues As a result of a December 18, 1984 telephone conversation between NRR staff (i.e., Messrs W. Gammill, C. Nichols, T. Quay, C. Willis and D. Lynch) and Detroit Edison personnel, Edison committed to submit a letter which addressed the follcwing: 1. Qualification of silicone sealant currently used in HVAC ducts (Enclosure A). 2. Clarification of'FSAR commitment to Regulatory Guide 1.52 relative to use of sealant (Enclosure B). 3. Documentation of NRR - Edison interpretation of proposed license condition on sample line loss issue (Enclosure C). 4. Discussion of submittal format of leakage reduction program results (Enclosure D). These issues are' discussed in the enclosures referenced above. The information reflected in the enclosures was previously provided to staff personnel via either the telecon referenced above or in a December 7, 1984 meeting in the Phillips building. 8501110185 850108 PDR ADOCK 05000341 A PM i I
Mr. B. J. Youngblood January 8,1985 EF2-72039 Page 2 Please direct any questions to Mr. O. K. Earle at (313) 586-4211. Sincerely, h M. cc: All with enclosures Mr. P. M. Byron Mr. M. D. Lynch Mr. W. Gammill Mr. C. A. Willis Mr. C. R. Nichols Mr. T. R. Quay U. S. NRC, Document Control Desk Washington, DC 20555 Enclosures s1 4 l t n .-m
~ ai. Mr. B. J. Youngblood ~ January 8,1985 EF2-72039 Page 3 bcc: Approval Control F. E. Agosti J. D. Black L. P. Bregni W. F. Colbert O. K. Earle W. J. Fahrner W. R. Holland W. H. Jens R. S. Lenart R. J. Letkiewicz A. K. Lim W. V. Lipton P. A. Marquardt T. D. Phillips M. S. Rager B. J. Sheffel M. D. Stout G. M. Trahey O. K. Earle (Bethesda Office) Secretary's Office (2412 WCB) NRR Chron File d e e--- - - - - +
Enclosure A EF2-72039 QUALIFICATION AND JUSTIFICATION FOR USE OF SILICONE SEALANT IN HVAC DUCTS The NRR staff concerns for.the sealant were: l. regulatory documents do not allow for the use of it 2. life of the sealant is unknown 3. elements of the sealant could interact with duct material' 4. negative pressure ductwork for control center ventil-ation system that is outside control center has indeter-minate integrity throughout life of plant. The following discussion will provide Edison's position on these concerns. 1. The governing regulatory documents applicable to air cleaning system ducts and housings are: Regulatory Guides 1.52 and 1.140, ANSI /ASME N509, the Sheet Metal and Air Conditioning ~ Contractors National Association Duct Construction Standards and the Nuclear Air Cleaning Handbook (i.e., ORNL-NSIC-65/ERDA-76-21). It is important to recognize that Regulatory Guides 1.52-and 1.140 presently refer to superseded ANSI /ASME standards (i.e. ANSI N509-1976 and ANSI N510-1975). Both N509 and N510 were revised in 1980. The latest revisions:do not prohibit the use of mechanical lock ~ seams or sealants for air cleaning ductwork. (The NRC has stated,.most recently at the 18th DOE Nuclear Airborne Waste Management and Air Cleaning Conference, i that the latest revisions of ANSI /ASME N509 and N510 are acceptable.) Edison recognizes that they do contain isolated restrictions. -That is:. ANSI /ASME N509 prohibits the use of sealants on -filter housings. (Fermi 2 does not utilize-sealant on engineered safety feature air cleaning filter housings for-any. sealing purposes except for duct connections-to housings.) Regulatory _ Guide ~'l.52 (Item.C.5.c),and 1.140 (Item lc.5.cl prohibits the use of' silicone sealants.for the temporary repairing or patching of holes-to meet the inplace DOP test requirements for HEPA filters. !The' silicone sealants used on' Fermi-2 ductwork'are permanent (i.e.,' not used as'a means-to meet inplace DOP test requirements for HEPA -filters) and.the Regulatory Guides allow the use =
L of sealants via reference to Sheet Metal Industry, Construction Standards. The silicone sealants which are used in the Fermi 2 air _ cleaning duct o systems are used to seal mechanical lock longitudinal seams and with gasket material at flanged joints..The use of sealant to seal . longitudinal seams _has long been a recommended practice of SMACNA.] + l 2._ Wyle : Laboratory Data Bank indicates the silicone seal-ant has an expected life of'40. years at an average-tem-perature of 202*F. As the average temperature j decreases the sealant life is expected to increase.- f (Refer to Attachments 1 and 2). Separate tests have-also determined that the sealant is qualified for t 1 x 10' rad environments (Attachment 3). Over _ their lifetime at Fermi 2, the sealants will be exposed to ( temperature and radiation levels well below these values. l~ ~ f , 9 i 3. The peel strength on galvanized metal is not published and would be dependent-on,.among other things, the temperature and--humidity of the atmosphere at the' time + of application. During the curing process, acetic acid may react with.zines to form zine acetate, a white s powder..If this occurs, the zinc: acetate powder could i inh'ibit the adhesion of.the sealant to.the metal. - This l! would'become _ evident during the duct leak test.. However, the adequacy of'the silicone to metal bond has been verified by the Fermi 2 duct leak test program. Once the sealant has been cured and tested, it is s F . virtually unaffected by environmental. conditions.. '4. The NRR staff. identified two sections of duct in-the-control center air conditioning system as potentially-h requiring leak testing'every refueling' outage. L Presently there are no regulatory--requirements or indus-try standards which address the design, construction, l-installation,-acceptanceftesting,_ or surveillance test ~ ing of_ air conditioning ductwork. The requirements are, therefore, to;be determined byLthe utility. Although Edison believes-the use of this silicone seal-J L ant is acceptable for this application, it recognizes the impact' contaminated leakage into the duct' sections outside the habitable envelope'would have on 'controly room operator: dose. It:was for :this reason that these ducts were leak' tested ~1n accordance with ' ANSI N510 during the preoperational test program,:even_though-this testing is~not required. The results indicate- ? that'the-presently installed duct system has low; leakage' characteristics.-- 1 = I e a
The staff concern that the subject duct sections, if sealant bond degrades, would provide a path of unfiltered inleakage from areas outside the control center is deemed by Edison to be unlikely due to the integrity of the sealant as discussed in Item 2 above. Edison has agreed, though, to a license condition which states that, before returning to power af ter the first refueling outage, Fermi 2 will: 1. demonstrate, to the NRC staff's satisfaction, that the silicone sealant will last for the life of the plant; or 2. conduct a leakage test on the portions of duct outside of the control center that could provide an unfiltered inleakage path assuming sealant failure (and every 18 months thereafter); or 3. replace the duct identified in paragraph (2) with welded duct. To provide further assurance for the Control Room air cleaning system, the airflow rates of the filtered out-side air (leaving filter T4100D0ll), the recirculation airflow rate and the total makeup airflow rate will be tested in accordance with Technical Specification requirements to identify any potential increases in inleakage. In addition, as part of the Fermi 2 maintenance program, the duct sealant on a representa-tive number of air cleaning ducts will be visually inspected for damage or lack of bonding at the same frequency as the airflow rate testing. J t i i i I I i
.. r~ ~ d ATTACHMENT 1
- KEY 00510 WYLE LABORATORIES DATABANK MATERIAL AGING DATA GENERIC NAME SILICONE RUBBER RTV THIC4 NESS BRAND NAME SILASTIC 732 SLODE.
8956.835654 GENERIC ABB SIR INTERCEPT -11.49977482 MANUFACTURER DOW CORNING' MAX AGE TEMP 140 ACTV ENERGY 0.77 RAD XHOLD 1.3E6 PARAMETER 50% ELONG4 TION ACT ENG A.L.# 029560A RAD A.L.# 028660 ~ REMARKS :ots weather, and cor.camination Fermi 2 criterion for 18-l 1. ACS housing and --Yes--- ductwork limitations measuring housing inte- -en maximum total /a. sea-r grity is the housing dif-leakage rate in ferential pressure. It accordance with shall not decrease more i j +N9f-NH4 than 4 in. H O in 5 min. 2 with initial internal t /g3pa y p pressure of 20 in. H 0. 2 /t O A-29 Amendment 38 - July 1981 i
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- -w+-
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4 EF-2-FSAR I CONFORMANCE OF VENTILATION SYSTEMS WITH RESPECT TO THE POSITIONS OF REGULATORY GUIDE 1.52 (Cont'd) Control Center Standby Gas Regulatory Position Filtration System Treatment System 3.0 Component Design Criteria and Qualification Testing (Cont'd) m. ACS fans on blower Yes Yes designed to oper-ate under environ-mental conditions postulated 12 n. Ductwork conform-No. Ductwork in accord-No. Ductwork in accord-ance with 5.10 of ance with 2.8 ORNL-ance with 2.8 ORNIr-ANSI N509-1976 NSIC-65. Q NSIC-65. o. Design configura-Yes Yes tion to minimize hazards p. Dampers designed to No No 5.9 ANSI N509-1976 l 4.0 Maintenance a. Easy access to com-No. Designed in accord-Fermi 2 SGTS entrance ponents in accord-ance with 2.5 ORNIr-doors are about 5 feet ance with 4.7 ANSI NSIC-65. high and probably will N509-1976 and 23.8 require a man to bend 18 ERDA 76-21 over. This is not con-sidered to be a hin-I drance for proper l maintenance. b. Definite mounting Yes Sufficient spacing for frame separation Component maintenance l distance (3 f t) is provided even though ( the recommended 3 feet [. is not always provided. c. Permanent test No. Permanent test No.' Fermi 2 has no [ probes with exter-probes provided but not permanent test probes nal connections in necessarily in accordance, and/or manifolds, only accordance with with ANSI N509-1976. couplings in the doors 12 4.11 ANSI N509.-1976 for DOP and Freon con-nections. l O d.. Periodic operation Yes Yes' .of atandby ACS 1 A-34 Amendment 46 - January 1983 k.
Innert (1) No. Maximum total leakage rate determined in accordance with ANSI N509-1980. Duct.and housing leak test developed and implemented using AN3I N510-1980 as guidance. Insert (2) ANSI N509-19 76. Duct and housing leak tests performed in accordance with ANSI N510-1975. Insert (3) except as follows:
- 1) For ducts less than or equal to 60 inches in dimension, transverse companion angles-are stitch welded on exterior of the duct, and the duct is bent or formed over the angle.
For ducts greater than 60 inches, transverse companion angle joints are constructed in accord-ance with Artical 2.8.
- 2) Longitudinal seams are mechanical lock type and externally brazed with sealant applied to internal duct' surfaces.
In addition, sealant has been applied externally to the seam to enhance low leakage characteristics. 4 L J 4 e
EF-2-FSAR CONFORMANCE OF VENTILATION-SYSTEMS WITH RESPECT TO THE POSITIONS OF REGULATORY GUIDE 1.52 (Cont'd) Control Center Standby Gas Regulatory Position Filtration System Treatment System 4.0 Maintenance (Cont'd) e. ACS components Yes Yes yg-. installed after active construction 5.0 In-Place hsting Criteria / a. Visual inspection Yes Yes before testing in accordance with 5 ANSI N510-1980 b. The air flow dis-Yes Yes 45-2 tribution should.be tested initially and 18 after maintenance that affects dis-12 '^ tribution N 6) ) 4 45 ..'O c. The in-place DOP Yes Yes e e ter ace ^ 111-ters should be in i accordance with ANSI N510-80 and occur initially l45 and periodically thereafter 45 d. Bypass leakage Yes Yes testing of the activated carbon yg adsorber section should be in accordance with l45 ANSI N510-80 45 Naks A[ l Q) A, s,hcen e sea /ea t is used as a permanen f f= m 3 *^^ sea / in //V/IC ow/worf I A-35 Amendment 45 - November 1982 W g- 'r 'sv 9-g --+ Ng -=9w-*--*'f' ye,*.ryww-v -qw--we--9-vwwwe wi'q...r-9y-g-y,a gg--w-g p.-a. .--mge ,.,----we-,%-er A-ee-we-w-eq-ww-----, gee w++s4m-4 w
-Enclosure C EF2-72039 In ithe December 18, 1984 telecon, Edison and NRR developed a mutual. understanding of the proposed license condition con-cerning1 sample system line loss. The license condition will require Edison to verify;that the iodine sampling system performs its intended function prior.to startup afterithe first refueling outage. It was agreed that the condition does not necessarily require a test, at this time,.for empirically determining sample line loss correction factors. The condition does. require that Edison evaluate.theicurrent system design to determine if a test of this nature is. required. As discussed in the telecon and in Detroit Edison to NRC 4: - letter EF2-72030,~ dated December 13, 1984, Edison' stated ~ ~ 1 that the Standby Gas Treatment Monitors meet their-intended function as described in NUREG-0737, Item II.F.1, Attachment 2. EF2-72030 further committed to develop and submit to NRR-a test scope, by. March 31, 1985, for. empirically detarmining sample line losses. The test scope document will-include an evaluation of the need and practicality of performing such a. test. 1 e 4 + i 'h 7 J-p <4 4 I 1 r
Encloguro D EF2-72039 3 LEAKAGt RFnUCTION PROGRAM RESULTS ^ FSAR Sectio'n H.III'.D.l.1 currently commitsLto submit-to'the NRC. staff a report of all recorded leakage 1and all preventive / corrective' maintenance performed as the; direct result of the evaluation of this leakage at the timeJFermi'2 reaches full power operation and before putting the unit into commercial service (approximately six months after fuel loading). This program:is consistent with other programs previously approved by the NRC. In response to the NRC request to_ submit test results prior to this schedule to support a timely review of the test t .results by the NRC staff, Edison will strive to submit an advance. copy of test results for 2-3 systems at a time, as they become available. The FSAR commitment, though, will be satisfied via submittal of a Leakage Reduction-Program Summary Report containing all recorded leakage and all preventive / corrective maintenance action taken as a result of performance of required testing. .i f k 4 F -? .-,..a. .a u.. -}}