ML20198G190
| ML20198G190 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 11/26/1974 |
| From: | Tedesco R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Moore V US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| CON-WNP-1019 NUDOCS 8605290274 | |
| Download: ML20198G190 (10) | |
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3 6 Docket Hos. 50-460 and 50-513
- 7. A. Moore, Assistant Director for Light Water Reactors, Group 2. L DRAFI SAFh"rY EVALUATION - WAS!!INGTOM PUBLIC POWER SUFPLY SYSTZ:!, UNITS 1 & 4 Plant Usuet Washington Public Power Supply System. Units 1 & 2 Docket Hos. : 50-460 and 50-513 Licensing Staget CP USSS Supplier: Babcock & Wilcox I
Architect Engineer
- United Engineers and Constructors Contairunent Typet Dry i
l Pasponsible Branch & Project Managert LWR 2-3; T. Cox Requested Completion Dates November 15, 1974 l
Applicaat's Response Dates N/S Review Status: Astalting Applicant's Emsponse Enclosed is the draft Safety Evaluation Raport from the Containment Systems Branch based on our review of the Washington Public Power Supply System, Units 1 & 4 PSAR.
As noted in the enclosure, we have not completed our review in the followin::
areas becauee the applicant has not provided suffici nt informations 1.
containment pressure respense analysis; 2.
subesapartment preneurs response analyais; and, f
3.
combustibla gas control for subcompartsmit.
i We vill provide our evaluation in these areas in a subsequent supplement to the Safety Evaluation Report pending receipt of the applicant's additions 1 infor: ration.
original staned by:
Robert 1. Tedeseo Robert L. Tedesco, Assistant Director j
for Containment Safety Euclosures Directorate of Licensing As stated ces See next page 8605290274 741126
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=--LOC':ET ::.6. 50-450 WC -513 6.2 Centainment Systers The containment systens for the, Washington Public Power Supply System, Units 1 & 4 will include a reactor containment structure, a containment heat renovsl system, a containment air purification and cleanup systen, a containment isolatien system, a containmer.t combustible gas control systen, and provisions for centnintent loahage testing.
6.2.1 Containment Functional Desiti The containnant will consist of a stecl-lined, reinforced concrete structure with a not free voluno of 3,090,000 cubic feet. Tho containment structuru util house the nuclear st.ean uupply systen, including the reactor, steca generators, ver.ctor coolnat pumps, and pressurizer, as uell as certain conponents of the plant cugineered safety features systems. The design pressure and tuaperature of the containment structure are 46.4 psig and 298*F, recpectively.
The applicant has analygod the containment pressure responses for postulated loss-of-coolant cceidents. Mass anu orargy release raten from the postulated pipe break to the containment were calculated by the CRAFT code. The resultu 'ecro then used cs inputs to the CONTPAST-S computer progran, which performs trancient thorrodynamic calculations with appropriate considoration of centainnent heat removal nyatcas and structural beat sin!:3, to calculate the contain-nent prescure.
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F In the analysis of the containn at pressure response the appliennt asaumed that there would be conplete stena-water mixtoc in the reactor coolant systen during the post-hicwdotm phase of the LOC.\\.
The effect of this assumption is to reduce the energy relesse to the containment. Since this assumption has not been fully justified, we have concluded that the containr:ent precsure analysis s!aould be repeated without considering the effect of steam quenching in the reactor coolent system during the post-blowdoun period. This analysis will be provided in a forth' coning arendment. Ce ulli report the results of our evaluation of this analysis in a supplement to the Safety Evaluation Report.
The appli::nt F.: c1:0 nnni; ::d u.e cen t a%"t p~aa"*o va 2 ~m a resultina fron a poetuinted f ailure of a urin ster:: line t:1 thin the containment including consideration of possibic singic active failure in the feedwater isolation system.
Uc have revicued the cualysis and have concluded that the applicant's calculate i peak containment preocure of 23.2 psig is acceptabic and wn11 belmi the design prescuro of the contninmant.
The applicant has not completed the analysis of the pressure responce within the interior compartmento.
A forthcouing avendment will pro-vide addittoaal information ragarding the subcompartment analysis and ue will report the results of our evaluation in a supplement to the Safety Evaluation Report.
Based on our review of the information presented in ti c prelininr.;
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Safety /malysis Puport regarding the ccatninment functional decinm ue cannot conclude at this eine that the containment d2 sign pr;osmre and the design pressures of the interior corpartments are acceptebic.
The resolution of thcae ustters uill be reported in a supplement to the Safety Evaluation Report.
6.2.2 containnent Heat nemova_1 Systen The proposed containment heat renoval systou will consist of tuo containnent spray trains.
The contcinment spray system serven as an 9
cngineered cafety feature and vill p$r ern no noruc1 operation function.
r The systen u111 be a sicanic Category I system consisting of redundant pipin,g, valves, pumps, and spray headers.
All activo conponents of the systen utJ1 be located outsida the containaent to f acilitate maintenance operations. !!issile protection will be provided by dircet r.hiciding or physicci separation of equipment.
The containaunt spray pump intakes from the containment sump will he enclosed by a screen asserobly designed to prevent the entry of debric that could clog the spray nozzles.
A high-high pressure signal in the containment fron the engiucered safety features actuation system uill automatitelly place the containment spray systcu in operation.
The spray pucps initially will take suction f rom the borated water storage tank (B"ST). When the water in the OtlST reaches a low icvci, the spray pump suction vill be manually transferred to the containmcrt nunp to initiato the spray recirculation phauc.
1hc applicant haa provided un c.nalycin demonstratint; that sufficient
net poaltive suctica head util be available for Loth tiny injectfud and rceirculation nodco of Operati:n.
TFin analysia nas perforr.cd consistent with the guideliner. of Result. tory Guide 1.1.
On the bcsis of our review of the proposed containment heat renoval systen, ue have concluded that the systen vill be designed consistent with the requirements of General Design Criteria 1:cs. 38, 39, cud 40, and is therefore ceceptabic.
6.2.3 contnttront Air Porf ficctica and Clvanun Svaten (Not Containment Syctcms !! ranch respensibility) 6.2.4 conta+n~.ont Isolation Svston The containment inolatictt av staa vill be e't.n1['ncel to putom.tti-11v isolate piping c:*.*te::s that penetrate the centnintent to prevent out-Icakage of the containcient atnosphere folle ring a pontulated lons-of-coolant accident.
Doubic barrier protr etion, in the for.n of closed systems and isolation valves, will be provided to casure that no single active failure will result in the IcGn of containment integrity.
Containment penetration piping, including the isoint:fon valves will be saismic Category I design.
Containment isolation trill automatically occur in two stages on containnont high pressure cir,nala of 4 psig and 25 peig.
Based on our revieu, we conclude that the proposed desi,nn of the containnent isolation system conforna to Ccncral Dauign Criteria ;;os.
54, 55, 56, 'and 57, and the reco~mendations of "et,ulatory cuida 1.11, and is acceptabic.
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. 6.2.5 Cc-bstfiele Gr C' erol S"a tc: s rollpwing a less-of-ecolcnt accidcuc, hydrogen tay accuraulate insido a
the cantainment
.,a a result of (1) a chcatesi reacticn between the fuci tud cladding and the steam resulting from, vaporization of energency core cooling water, (2) corrosion of construction r.iaterials by the alkaline spray solution, and (3) radiolytic decomposition of the cooling unter in the reactor core and the ceatainment sump.
In order to mitigate the consequences of hydrogen necumulation in the containment, the applicant propoces 'to pcwide rodundent hydrenen reconLiners, uhich will be locnted outsidu containment, and a backup purgo nystem.
T.n ah of the 100% cnpacity vnennhin ru will ho capa!.la nf pv<.caeafnu a minitum of 50 standard cubic feed por minute (sefn) of containnent atmosphere for post-accidant hydrogen control. The applicant bas not mado a final decision as to the type of recombiner that will be used. The recombiner ocuuf acturers are conducting qualification testo on production units.
The results of thecc testa vill be re-viewed by us prior to our acceptance of the recombiner selected.
The reconbiner system will be designed to seismic Category I design criteria aad to the IEEE requiremento for an engineered safety feature.
To ansure adequato mixing of the hydrogon in the containecnt, tha applicant propooco to periodically activate the contatnnent spray system.
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A post-accident hydroacn purge avutem will he provided to serve l
as a backup to the hydrogen' recotbiner unitc. A purging rate of 80 scfm will be through HEPA and carbon filters.
Hydrogen analyzers 1.
and alarm systems vill be provided to allqw periodic monitoring and analyzing of the hydrogen concentration in the containment. 'At least three independent points in the containment will be sampicd to monitor the hydrogen concentration.
The applicant has performed an analysis of the post-LOCA hydrogen concentration in the containment buiiding consistent "ith the guide-lines of Ranulatory Guide 1.7.
Using thece guidelines, the applicant has calculated that the hydrogen concentration in the containment util not reach the louer f1:rmability Jinit of 4.0 volume percent with one recombiner in operation.
The hydrogen concentration in the contc.inment will be maintained below 3.1 volume percent by actuating one of the two recombiners approximately eight. days following the accident. The backup purge system, if initiated 19 days after the accident with a purge rate of 80 scfm would licit the hydrogen concentration to below 4.0 volume percent. We have perforned similar calculations for th2 hydrogen generation in the containment follouing a LOCA and our resulta j
are in agreenent with the applicant's.
l The applicant has not completed on analysis to show that adequate mixing of hydrogen within the subcompartmento will occur and that l.
hydrogen concentrations uill remain below the guidelines limits I
stated in RSgulatory Guido 1.7.
A forthcoming amendnent will provide s
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additional information roccrd.ing thic Matter.
The renolutica of these natters ~ vill be reported in a supplement to the Safety Evaluation Report.
6.2.6 Conteinment Leakage Turigyroerg.1 The containment design vill include tha provisions and featurcs which satisfy the testing ;cquirements of Appendix J to 10 CFR Part 50.
The declgn of the containcent penetrations and icolation valves vill permit periodik'1cekage ' rate testing at the pressurc specified in Appendix J.
Included will be those penetrations that s
have resilient scale and expansien hellous, such as personnel airlocks, emergency hatches,. the ref ueling tube blind flange, hot process line penetrations and electrica.} penetrations.
The proposed reactor containment Icahnge testing program complies with the requirements of Appendix J to 10 CFR Part 50.
Such compliance provides adequato assurance that containment lenkticht integrity can L
- be verified throughout the service lifetime of the plant r.nd that the leakage rates will be periodically checkhd on a timely basis to main-tain cuch leakages witjiin the specified limits. Maintaining contain-ment lenhage rates uithin such limits provides recconable assurance that, in the even.t of tmy radioactivity releases uithin the contain-l
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, ment,mthe-los's of the containment atmosphere through leak pathenwill not be in execco of acce'ptable litits specified for the site.,
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- t le tc. testin: p re;;rc ccuplica rith :he requiter::nto of l.o; cadi, J u 10 CFR 50, and that such comp'. lance coastit ucca..n ecceptch.1 <
is. mis f or s 2tisfyir; the requirm.ents of Concral Dmiga Criteria aos. 52, 53, and 54.
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