ML20024C743

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Forwards Responses to NRC 770318 Request for Info Re Selected Technical Issues for Vendor Participation Published in NUREG-0138 & NUREG-0153,per
ML20024C743
Person / Time
Site: Crane 
Issue date: 07/28/1978
From: Taylor J
BABCOCK & WILCOX CO.
To: Mazetis G
Office of Nuclear Reactor Regulation
References
TASK-07, TASK-7, TASK-GB GPU-0494, GPU-494, NUDOCS 8307130203
Download: ML20024C743 (13)
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1 ~: gfy* t/ffn1stxt -j y c:; mis' Babecci(rM!cox m en maemtana,u s.=sessa Team,e moe m u h s ~. [ July 28, 1978 / Mr. 8. E Masetts b Reacter Systems Branch Divistem of Systems safety Office of Nuclear Reactor Asgulaties-E S. Nucigar Regulatory Ceanissica Washington, D.C. 20535 I Seferencess (1) Letter and Inclosure 5. F. F. Bass. Jr., NRC, to E. E. Suhrke. 34W, March 18. 1977, subject Technical issues for Vender Partietsattoa j (2) Letter, James L Taylor, 34W. to C. E.Hazetis, l-NBC, Angust 22, 1977, same subject

Dear Mr Nasetis:

Raclased are three (3) copies of our responses to 'the so selected technical issues published in NU21G.0128 and NORIG-0133, requested by your letter of March 18, 1977 (Beforence 1). These responses are in accordance with our 3] 1stter of August 22, 1877 (Reference 2). If you have ear further questions conceratag this matter.- lj plasse contact Mr. William R. Speight (1st. 2SO2)'ei y taff.,.. , Very truly yoursiyr ,d Ln [k .3 James N. Tay1 Nasager, Licensing 4117:dsf s f{ Inclosures' ces R. 3. Bersum (3(w) ~ bcca

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p-i. w I, n.i \\ ha genent of Men ssfet, cende testement'in pvstostiene stuastes steas une ereas ucsoents .j r4'. M t i (. Babcock sad W11ces basically supports the NRC position as expressed . { L. ? q in NURgf. 0134 La regards to the use of sea. safety grade equipment g s. g as back to safe co onents during a staan-Line break. ' The n' g number e issues ra sed y secondary.systes transients is large L t. and ceaplex enough, that a systematic approach to all secondary treasient issues should be undertshes. Therefore, in lieu of

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reiterattar the analysis assumptions currenti in recent SAR sub-mittals. SW proposed a series of meetin a vi the Ceanission 1eading towards final resolution of the l 5 f .s - secondary system induced trsasiests. asues involved with,

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B ..u a. s c. } .) ? - i__. p j p -i j ,g j .e ) a 0 ., j *.., 1s,s,3g,J,,a Delaved less of Offstte Power Pe11ewiar a LOCA* I l .,tU A. Offsite power remains available following a LOCA: the 8

  • diesels start; at seas time after the LOCA effsite power It sg is interrupted; critical lead 2 are interrupted for a

'i' short time until sequessed en to the diesels.

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3. Offsite power reaalas available followier a LOCA: the *

  • diesels starts at some time after the LOCA and the ECC5' signal is reset offsite aketdeum leads (met ECCS) power is laterrupted, safe 9

are sequenced sa (the '. I' diesels any mise have been stepped, is which case:ther . ~ will have to be restarted).

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33333331: j. This 1sses raises the sencets that the less of offsite power at ? 4 sees time follow a LOCA would result in auch more severe de* esasequences than i effsite power were test sensurrent'with the t' ! LOCA transient. A study was performed to assess the nazimum I' -

  • "*..*.s est of a less of offsite power (LOOP) at say time fellowing 9

LOCA. A minor increase as peak claddiar temperature was ebtained: however, due to the sufficiently Iow probability for this assurrease. 34w fests that it is met necessary to consider g; 1007 subsequent to the LOCA. pellowing the LOCA. the ISPAS signals will actuate the* diesels, and will attala rated voltage"and speed withia 10 sesseds. If offs te power is them.last at seas time after the LOCA. automatic sequencing features are provided se that interrupted M ECCS flew '.e the core is fally re-established withia 20 seesada. Per BEN's plaats, the ESPAS signal is act required to be reset. j* Thus, part 3 et this issue is met to be~ addressed. l l Am. analysis has been perforand to assess the p double eaded t of a LOOP t* after a LOCA. The worst ease break, an 8.5L ft break 'et the piump discharge with a Co

  • 1.0. for SEN's 205 FA plaats was re. analyzed assuming a LO3P at the time the CFT's '

empty (36 seceeds). A delay of le seconds was them assumed before the BCCS flow to the core was fally re established. A ] 100P at the time the CFT's empty will yield the naziana tapast en peak sladding temperature for the fellowias reasons 1. Prior to the time t:se CFT's empty, the laterruptions of-ECCE. flow because of a 100P would be less than 10 seconds g* des to the continued flew free the CPT's. Thus, the imps weeld be less severe than ti.at analysed. 2. At any time after the CPT's empty, the amount of time

  • hat ECC3' flow would be interrupted dos to a LOGP weald be the same as that studied. Newever, for a 1007

, ? that occurs lates thaa the time the CPT's empty, the sore geench frams would be higher and the sore decay j heat lower than that analysed. Both of these conditions y , will result in less-severe ceaseguences than that en=imad. 4 i 1,. I j [ F 15 'M l' I'. l t . ~

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L... ~ s;.e il* f.i [ 3 is lessense to issue 4 (Cent'd)., The results of the ' analysis showed that the peak cladding j-g temperature Sacreased 70 7 to 2144,,7.

  • It is important to mete that this ame1 sis was' performed'for 7

l '.". 34W's 305 FA staats which utilize Mark C (17 x 17) feel. Das to a alty en Mark C refleeding heat transfer esaditions (0.3 tiplier sa the F12 CIA predicted coefficients), the sensequences ?, of the LOOP ars highly everestimated. Because of the penalty. 8 'i-anaimmt cladding temperature after the time the CFT's empty toads peak sladding temperatures occur,at opprezimately 100 seceeds rather than at approvinately 40 seconds as obtained for plaats Ie with Mark 3 (15 x 15) feel. The extended ties to reach the that stad?.iag temperatures would increase less tha. it is espected to enp*1fy the impact of the LOOF. Realistically n 30 F. l q-f- The results of the analysis discussed above obviously seemd the' I Nl 4 effect of a LOOF subsequent to the LOCA for all Sgv plaats. Ia * } it should be meted that the scenarie of events addities,is h 'j! analysed ble imprehable. If the less of offsite poser is a result of a gr perturbaties due to the LOCA, the less shea14 t4 : escur within the first few secoats which is the.present analysis g method. Thus, this sencess addresses an indey=d==t less ed Pouer. The probability of am 1A. ' t less of effsite poser la a ens neer period, according to WASE.1400, would be about one skaase -l. la 50.300. The likeltheed of a large LOCA is about ene chasse i 8 ' ;5 e4 la 10.000 per reacter year. Furthermore, the analysis that was assumes a stagle failure of.on.e. diesel,whi.ch is about -ility of - - ~ per. formes.e in 20 is.ma se seen, th. to.4 r.

e..aa this sequence of events is very les e

t* As illustrated for SEN's plaats, the tapact of a LOOP subsequest. -l to a LOCA results is only a miner impact sa peak sladding ii ture and does met endanger the public health. Also, the.,j ability of the event is estremely low. Thus, the LOOP ~ 11 swing a LOCA meed met be seasidsrod for 30f's plaats. j l r- \\ .3 s h I t t, j ,I. V 4< ] { .I. { F15 ;9 6 8 2) [ '325T9 9 Ol ~ l. f 6 i e

l l ~. t a t. f ^) m 1 ) i n-fC [ - - - = I,, .s,9 lif jb A j Ms Analysis of Postutsted Roseter Caetant Pm Reter i. aes:ure incaments !i; ih n. b.r=== 'y the situaties of a concurrent i.e. staultaneens locked retor and less of offsite power is considered as incredible event. e Therefore, the situaties analyzed la response to this issue is a l locked roter event with less of offsite power resulting from the . ~, subsequest rascter. turbine trip. The sequence of events for a tacled*Reter'Transiest with a less-t,. of effsite power as analyzed is gives in Table 1. As can be seen. [ a cesservative value of ISO millisecents is used for the time I between turbine stop valve acties ase less of power to the RC Famps. The systes rosynsee is shown in Figures 1. I and 3 for L if the mestros power,.systen pressure ar.4 AC flow respectively. \\ The resultant D(31 ase stad temperature response is skews is Figure 4. As is clearly shows. the less of offsite pewer has a. =,{ segligible result en the peck clad tesysrature. This cesparative lg result holds true for all 34W reacter types, altheagh the -result ..l. ef the locked retor transient asy vary depending sa plaat type. i p {, g ! 7 t O. ?? ut I; e. \\- n

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  • IME' Occurs 8.79 4

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I 4 q '* Mt preeuence Decsv N 38.s33Ls,p Theprotectionphikesophyemployedbyall11Wplaatsagatast' flew amena11cs has been the use of a flux-te. flew trip feature. a. 71 f parther protecties agatasc less of pusrs is provided by the pump J. It is S&W'r posities that power mesitor status trip functies.these two 373 trip functions adequate

  • pestvisted transiests and no addittoast protective devices are Justificaties of this posities is gives is the accessary.

.I fellowing persgraphs. A simplistic view of as underfrequency transions is to assume a 1 to 1 ratie betwesa percent frequency decar and percent fle Therefore, the 1 to 1 ratie assumpties is cesservative a reducties. tIg Also, the primary i4-assumed to azist fer the discussies to follow. issue has been decay este, whereas. in reality, there exists two der. Cae is the decay rats for.a sua. frequency limits to c We tained underfrequency transients the other is a minimum frequency W. above which sufficient flev exists as prevent CNE fres occurring. ai, per aes sustained decay rates that recover to assimal frequencies prior to total frequency dec.ty below this ralue, the core remains J. The fluz.to. flew trip setpoint is determined by one.

  • . two. er four pusy coastdeva depending en whethe protected.

3 m ,: L. pissp somiters, respectively.the plaat is protected against that fisw reducti j'

  • l The nised,f the source, l.a.. less of pump (s) er underfrequency.

less o. flew trip setpoint then deteraiaes the sustsiaed decay

41 e

rate for which protecties is provided and typically ranges fres l 'i fluz.to 1.6 Et/sec to 1.6 Nt/sec for 34W plaats. ~ If 1911 et rated power is divided by the flas.ts. flew rette. a If conservative flew is established such that no CN1 occurs. this flow is ceaverted by the 1 to a ratie assumpties into a say frequency decay rate that recevers.before the 4 ) It is the responsibility is below typical values of 5d to 37 Ns.

  • ef each applicaat to deseastrate grid stability within this range.

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g ) r E .. ~. - --.~-.,~-.:; ~ I i P.. ~ t- ~- , =...,., .,1 - ': sM.w.~ -m j' f a( h t. ..f.... tture ~...,1s,s,y,,1p passive Mechaatcal valve f a + r ,as-d .h8 assive mechaalcal valve at see not already benaded jji As as intriating) event, there are noTo be as taitiating event, a which could occur failures (FMVF's h re, l-FMYF would have to be postulated la the seceadary plant w e by esiattag 341f safety analyses. ^I r line as sa example, a less of feedwater accident er feedwate culd .;{ break weald benad valve blockage. Ne other valv h ins , '! ( ,? esisting redundancy requirements for safety re ie r. failures of t 't As a sia le failure folieving as event, there are noc separa -f hich are blockage and safety concerns ggi,ded, that valves w a valve o already opes are assumed to retaan astegrity. i of data gathering programs, we feel tha f [ r, Regarding the afog lacking; however, several 3enerally the availafailure in forty years is presenti to determine prob-9$ ndervsy. T excellent industry programs to col set such data are u I* and it must be coatluded that data sufficientskility est j! . ~. - -... lsa i' It is expected that the eversti probability of an event p u nl ' pMYF et a critically located valve is very law. j *! ' i ; t, -

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