ML20214T750
| ML20214T750 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/11/1986 |
| From: | Dunn B, Pawug J BABCOCK & WILCOX CO. |
| To: | |
| Shared Package | |
| ML20214T726 | List: |
| References | |
| 51-1164527, 51-1164527-00, TAC-62086, NUDOCS 8612080684 | |
| Download: ML20214T750 (9) | |
Text
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$NGINEERING INIORMATION RECORD -
Safety Related:
Document identifier 51. #6 #2.7-M g 6 Yes I No D Titie 'DB set.o M A3 4 . A-~ , % L L =f 4
- r. i Prepared by 14. 4W '
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Reviewed by bin KMk M== Date- 1 le '
Remarks:
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S I- 16t!IE7-oO MamxTm his document is prepared in response to Task 707 - sall Break IOCA Assertions.
It directly relates to the TID Davis-Besse 1 nuclear plant SBIDCh analyses perforund by BGf. Se purpose of this report is tot determine the basis for and assaptions used in various SBIDCh analyses, walusta this information ip .
comprison to current plant praeters and opration, and govide conclusions-as to arty issues that may exist due to differences that are discovered.
In prticular, Task 707 addresses the following analyses:
- 1. Bm-10075A, Rev.1
- 2. HPI Line Break , , . .
- 3. Core Flood Line Break , )
- 4. AfW work, circa 1983 1
- 5.
- Blue Book" Analysis
- 6. BMf-10j5'4A i
- 7. 0.5 ft alOCh Each of these analyses vill be investipted and waluated for purposes descibed above.
BAclG Glc .
Em is currently performing an analysis pogra for the Bei 0#ners Group Analysis cannittee to resolve the issue of NLREG-037, Itan II.K.3.31. Bis peticuhr its requires analysis of a sBICCA spetrum utilizing the rwised evaluation model poduced in empliance with Ita II.K.3.30. Se results mist demonstrate conformance to 10CPR50.46 requirenents.
In further correspondence, the US NC provided clarifying information that the requirements of II.K.3.31 could te utisfied by denonstrating tlat stDCh analyses using gefously apgoved waluation models are more limiting than analyses using the twised (II.K 3.30) models. But is prfonaing analyses within this approach for the BsWOG.
Pbr the prescribed appoach to y sucessful, a caprison analysis is necesary.
Por Datis-Besse 1, the .04 ft Q.PD SBIOCA was chosen as it exhibits certain 3hencuena of interest and was performed gwicualy as reported in Bm 10075A, l Rev. 1 (Buf. 1) . A caparison of assaptions denonstrated differences between the gwicus model Se four anjor areasof(circa norMonfonnity 1971) and cwrent oprating prameters of the plant.
were:
- 1. RC5 low possure reactor trip setpoint
- 2. 83 wailability l' 3. A19f Iwel control setpoint
- 4. Mrw coastdown
! Each of the severi gwious'y identified analyses will be evaluated apinst the above 4 Items, and any others that mi@t arise during the review.
2.
fl-IlW f27-oo Limnaian Analysis '
Se requirements for ICCA models and acceptable analyses results are as specified in 10Cm50 Apperdix K and 10cm50.46. Se BCG sust be abown to confom to the acceptance criteria. Mr this reason, conser**atiw and bounding asmaptions are requi. red of various plant praeters, and sensitivity studies are prformed j to determine offlects of other plant praeters on ECG perforsance. :
1 Serefore, it is entirely possible that f.be assuptions used for licensing calculations may not accurately reproduce plant oprations and setpoints.
Bowever, these asstaptions should regesent possible oprating conditions in a 1 conservative and bounding manner. Realistic and best estinate analyses are !
prfocned for reasons other than demonstrating conformance of the EG to the ~ !
acceptance criteria of 10Cs50.46 (i.e. AEG verification).
l j
Se evaltation of the aforementioned analyses, as concams the asstaptions l differences, was perforned in visw of the licanning reguirments as just explained i Q2ERAL DISCUSSION ,
Se four areas of asamption differences are discussed in general as concems EECCA licensing calculatims.
Low Pressure Reactor Trio Setpoint
, Se current analysis setpoint is 190'0 psia which is tased on the Tech setpoint less errors. All analyses irrestigated herein use this se eacept BNt-10075A, asy. I and the CF Line Break which used a setpoint of 2065 pata. Se Davis-sesse FSAR, Qiapter 6 states that 2050 psig is the meiable pressure-taperature trip setpoint. The variable IW setpoint is considered a naninal value that could be used for analysis. Mr SECCA lican analyses, the loss d offsite power is asamed coincident with reactor tr mitil reador trip occurs the ac ptaps and the .Mrw pumps are still oprational.
Berefore, 5 heat removal at full pcwer is maintained and a heat generation, heat renoval balance occurs. Although 1900 paia is more consorsative, it abould not have a sigiificant impet due to thin 5 balance effect.
E Availability l
The analyses reviewed modeled the availability of toth s's, the one loop models assuned twice the heat transfer area in the one 5 to dfset the model limitations. E!DCA licensing analyses assam a loss of offsite pcuer, IOCP, coincident with reador trip. Se worst single failure criteria then assmas the unavailability of -one diesel generator. Base asamptions limit the BCG +
anilable for core cooling. In the Davis Besse plait the diesel fallire also j results in the inability to feed one 5, as one AN contml valve will resin closed and the APW syste is not cross-conneded. Berefore', the DuriNiesse plant will only have APW available to supply one 5, however both generators will have inventory available for heat transfer until dryout. Berefore, the '
issue is the effect of M heat transfer after APW actuation and asymetric prformance. A review of available literature including licensing calculations 1
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51- ll W G7-%
.o has detersdned that sG availability is not a esfety issue and the sacrosente effects on these transients will be negli e. Specifically, the ' Blue BocP, auf. 5, analyzes asymmetric sG effects symmetric so analyses. Concerning SG heat Movides results that are similar to transfer via AM, the influence on transient results is a function of break size. -
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per most sauX1's, area greater than .52 ft2 (Raf. 4), the SG's are notf needed to demonstrate e<= +41e BCt3 performance.
In general, etcCh's are cssmble of depressurizing the als sus that a . negative tagerature between the giary and secon&ry sides of the 83, and the 83' gradient s act as aexista heat source. Analyses (Def. 7) demonstrate that reverse SG heat trander has a negligible effect on tock transients. Sherefore, the nater of SG's andelled, or the equivalent effect through feedwater supply or increased heat trander area, would have a negligible impact on these analyses results.
Certain size SBux2's (area of apgozinately .01 ft )2 do exhibit the need for SG heat transfer after AN actuation. For these SUX1's the neber of SG's is not inportant so long as adequate condensing surface is available. Before any core uncovering occurs, the plant desip .is sud that the acs levels aust decrease to where stem exists in the primary side SG tube region. Condensation (M cooling) will occur if AM is injecting or a secon&ty side pool leel of sufficient hel$t is established. 1he result is primary side possure control to appoximately the SG stessure (- 1000 cooling throu$ ECC3 (BPI) prformance. pai), which then guarantees long term Minima values for AN ficw and 5 pool levels, toth affect heat transfer ares, have teen etermined for the Bei desiped plants (Raf. 4 and 10). D4. specific calculations, Raf. 4, conclude i
that adequate best transfer will be obtained fra a three foot Iwel in both s's ;
(equivalant to the heat transfer area of a six fbot level in only one SG). the :
heat transfer aren associated with a SG secondary pool hei@t of 3 ft (in each SG) will recove all the core decay heat gior to core uncovering.
t If the available pool hei$t is increased then the heat trander area for M cooling has also been increased. She effect will be to ywide heat tresser !
earlier as the N3 won't have to drain to the lower pool M t. However, the transient respanse will be basically unchanged with the esc @eption af +4=4*
Cnce H cooling is established, ginary side gessure decreases and is controlled naar the seconery side sturation gessure and the EPIS is asable of maintaining N3 liquid inventory above the core elevation. i M cooling can also occur on the Am sirsy itself. The AN injection velocity poeides a heat treater area, the bl@er the AN ficw rate the larger the heat transfer area. All previous discussion concerning B< cooling and the SG pool height are also applicable for AM sgay.
l Therefore, ,althou@ the mador of 'sG's modelled any be different, overall 4 transient results should not te altered considering the different heat trender areas modelled. In addition, the mirdann heat transfer requirements have toen set in such a way that these analyses being rerfewed remin valid.
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Sis issue is closely coupled to-the perious issue of 8G andelling, and, as such, the same arguments pwail. sesically, the analyses zwisued hwe 4
incorporated various level setpoints (32' to 10') for ArW contml. ~ m e level
! setpoints have been modified throughout the plant desip history, Se analyses were performd, in part, to verify the SG 1eral setpoints. Serefore, depenhnt on the analysis performance time frame, different m level setpoints unre verified.
Otrrently, for SBun with IIKP and single failure of a dLeaal generator, the plant will control one 5 to the 10' level. As pwicaal:r -
stated, ant. 4 goncludes that a 3' level in both SG's (equivalent of U laem',
in one SG) will result in sufficient heat transfer area to pavide satisfactory heat trader for those saun's where gassure control is necessary. As i geviously discussed, the gimary-to-es.ondary differential level 4termines (
the condensing surface available (heat transfer area) for 3 4 cooling. If I additional con &nsing surface is available, ie 10' to 32', then the a-c cooling gocess will begin at earlier transient tinas as tha primary side level vill not have to decrease as such. However, the same reruit will ensue. Primary side pressure control will be maintained close to the sG possure (ginaryto-secon&ry coupling through BC cooling) eere the HPIS can naheah inventory and eventually refill the RCS with the natural reduction in core decay beat.
s coastdown ,
Again, as this issue relates to the SG, the arguents are as previously discussed.
9hrious m coastdown times have toen included in the analyses rwiewed (fra 43 sec. to 10 sec.). Current plant infocustion indicates a seven second NN coastdown time. Calculations have teen performed (Ref. 7) that duconstrate the effect of longer MrW coastdown tines on the subcooled blowdown phase to saturation 1 gesstre is negligible, ne initial degessurization will not to affected, mis can be explained further through review of the natural circulation shame.
Analysis results denonstrate that APW injection ecssances minutes before natural circulation ceases. Without forced flew, RC. pumps trip at uxP, E dryout will not occur before ArW injection begins. Ihough 5 inventory exists such that the Mrw coastdown is not a determining factor of any transient result. S e 8-C cooling gocess is unaffected by the MEW coastdown time. With APW injection the 10' level metpoint will be established, with or without MrW, before BC W i g occurs.
Se other issus would be increased SG inventory at the hich MrW temperature.
l Bis would effectively add to the reverse beat transfer pocess as gwimaly discussed, and therefore is considered conservative. To place the reverse 8G best transfer issue in perspective, Ref. 7 evaltates this grticular issa and concludes that the effect of the SG as a 0heat source is miniani such that the 6ange in PCT is negligible (less than 20 F). ~
Analysee Retiew
! End of the analyses listed has been reviewed for asstaptions used and a cxzgarison is gesented in Table 1.
5
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String the rarfsw gooses, one additional its arose eidi has been latal discussed between TID and Ber.
versous analyses versus carent WI 'the issue syste comems thetests.
performance EPI flaw rates used in i Bis report will l j not (2esk relata 55). details of this issue as it has toen realmd throuWi another task -
Bowever, it is noted that the result of the EPI flow eralation Olaf. 8) poridad a revisedall justified BPI perious flow curve satlX2 foranal use.in futwo BriX2 licensing evaluations, and l results as acce BPI flow curve instead of that in the specific ana@ lyses.a given the rarised l
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table 1 Analyses Assaptions Cugarlsen Law Pressure ARfkevel Baecter Raber- Control
~
~Ist Annivn== Trin at; point int g gi's pn Omstdown (paia) )
(sec)
Blet-2 % Bev. 1 2065 2 32 43 W I Line Break - 1900 2 10
. , 25 CP Line Break 2065 2 44 H4 Al%$UG Evalation , WA 2 ' 3 to 10 Iq/A .
"Bita Bock" Analyses 1900 1a2 10 10 to 26 BleM0154 1900 2 10 14 B uXX 0.5 ft2 1900 2 20 25 1
Ibtes: Wb -let detemined at this time 4/A - IDt applicable ibe the method used 0
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GME2artas ~ '
A rarisw has been empleted of certain Davis Gesse 1 NEDCA analyass assumptions.
These analyses include licensing calculations (i.e. BMF1007% Bur. M and
- - calculations performed to poride an inforanties base (i.e. " Blue Book') for wrfous atDCh annoems.
AN level omtrol, and MfW coastacun. the values varied as tmasaw to the assaptions gejously discusseds low pressure , .
&sigt ;
- evolved and the analytical position on asamptions changed. As mriations of these garameters within the ganges that occured are not herein.
l criticut to these ICCh evaluaticas. 1he conclusion of this report is that the asmastions .
used foc ead of these analyses re5 resent accostable positions and the analyses remain valid for plant licensing, .
l 1
As a final note, the purpose of the current 5803 analysis gogram to ad&ess j
NORBM737, Item II.K.3.31, is to demonstrate the omservativeness of pericus BIDCh analyses. t It is anticipated that the II.K.3.31 program will poride
- analytical results did will confirm the conservative and acW*e results 2
of all pcw$cu's SIDCh analyses.
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f/-Il6 YD 7-oo l
i annects 1.
Blef-10075A, Rev.1, "Multinode Analysis of ein11 areaks for ser's 1774ual-Asambly Raelaar Plants with Aalsed Isop Arregament and Intemals m nt a lves", h rsia, 1976
- 2. Bei Doceent 33-419440, "NPI Line Break', Mand 1977 3.'
, Te Doria-tesse FmR, Chagter 6, Core mod Line treak
- 4. a m Docuent .
Mardi,1983. 32-1141304-00, 'soilerg.ondenser Mfectivenssa stu%', ~
5.
sw asport " Evaluation of Transient Beherfor and anall manctor Maht Syste Breaks in the 177 FA Plant," 'May 7,1979 via letter J. B. Taylor to R. J. Mattson 05C) dated May 7,1979. IgC Public Doceant Roaa, Accession #7905190164. , .
6.
Tosical Report, .am-1015&L, ilm's Small Break ID(1 BCOB Emluation Model", July,1985. .
- 7. .
But Docisment 32-1164526-00, Muntion of am-10075 Boundary conditions",
M. A. Rinckel, My,1986
- 8. Bet Doceent 32-115975141, 'BC(3 WI Flow De a w+4aa Justification", My UN. ,
- 9. B W Doceent 33 4518-00, " Davis-Besse 1, 0.5 ft2 min 11 areak Analysis",
Jan. 1975.
- 10.
Bef Deciment 77-1141270-00 " Evaluation of SEDCA operating Proeschres and MSSs*, Efectiveness Feb. 190. of amargen,cy Mednter 83 ray for Bar Desiped Operating j
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