Text

Requests Proprietary Westinghouse Responses to NRC Requests for Addl Info on AP600 Design Certification Test Program,Be Withheld (Ref 10CFR2.790)
	ML20094H907
Person / Time
Site:	05200003
Issue date:	11/10/1995
From:	Mcintyre B; WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:	Quay T; NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML19317C094	List: ML20094H907; NRC-95-4594, Forwards Proprietary Westinghouse Responses to NRC Requests for Addl Info on AP600 Design Certification Test Program. Listing of NRC Requests for Addl Info Responded to in Ltr Contained in Attachment A.Responses Withheld,Per 10CFR2.790;
References
	AW-95-901, NUDOCS 9511140402
	Download: ML20094H907 (87)
	v • d • e

{{#Wiki_filter:- / \\ a t a \\%j Westinghouse Energy Systems Ba 355 Pittsburgh Pennsylvania 15230 0355 t Electric Corporation AW-95-901 November 10,1995 . Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 ATTENTION: MR. T. R. QUAY APPLICATION FOR WITHHOLDING PROPRIETARY 4 INFORMATION FROM PUBLIC DISCLOSURE l

SUBJECT:

WESTINGHOUSE RESPONSES TO NRC REQUESTS FOR ADDITIONAL INFORMATION ON THE AP600

Dear Mr. Quay:

The application for withholding is submitted by Westinghouse Electric Corporation (" Westinghouse") pursuant to the provisions of paragraph (b)(1) of Section 2.790 of the Commission's regulations. It j contains commercial strategic information proprietary to Westinghouse and customarily held in confidence. The proprietary material for which withholding is being requested is identified in the proprietary version of the subject report. In conformance with 10CFR Section 2.790, Affidavit AW-95-901 accompanies this application for withholding setting forth the basis on which the identified proprietary information may be withheld from public disclosure. Accordingly, it is respectfully requested that the subject information which is proprietary to Westinghouse be withheld from public disclosure in accordance with 10CFR Section 2.790 of the Commission's regulations. Correspondence with respect to this applicatiori for withholding or the accompanying affidavit should reference AW-95-901 and should be addressed to the undersigned. Very truly yours, L. Brian A. Mc nt e, anager Advanced Plant Safety and Licensing /nja ec: Kevin Bohrer NRC 12H5 2619A 9511140402 951110 PDR ADOCK 05200003 A PDR

AW-95-901 1 AFFIDAVIT 1 4 1 COMMONWEALTH OF PENNSYLVANIA: ] ss COUNTY OF ALLEGHENY: l Before me, the undersigned authority, personally appeared Brian A. McIntyre, who, being by me duly sworn according to law, deposes and says that he is authorized to execute this Affidavit on ] behalf of Westinghouse Electric Corporation (" Westinghouse") and that the averments of fact set forth in this Affidavit are true and correct to the best of his knowledge, information, and belief: O/. oA/8 1 Brian A. McIntyre, Manager i Advanced Plant Safety and Licensing Sworn to and subscribed before me this /# day i of .1995 l ( Notary Public NotarbiSed Rose Mat Paync,&fary Public 2 Monrx4e Doio./.bJay 33a fay Commesion E4 ires Nov.4,1 Marteer, Pemspvans Assooanon d Notanos

AW-95-901 (1) I am Manager, Advanced Plant Safety And Licensing, in the Advanced Technology Business Area, of the Westinghouse Electric Corporation and as such, I have been specincally delegated the function of reviewing the proprietary information sought to be withheld from public disclosure in connection with nuclear power plant licensing and rulemaking proceedings, and am authorized to apply for its withholding on behalf of the Westinghouse Energy Systems Business Unit. (2) I am making this Affidavit in conformance with the provisions of 10CFR Section 2.790 of the Commission's regulations and in conjunction with the Westinghouse application for withholding accompanying this Affidavit. (3) I have personal knowledge of the criteria and procedures utilized by the Westinghouse Energy Systems Business Unit in designating information as a trade secret, privileged or as confidential commercial or financial infonnation. (4) Pursuant to the provisions of paragraph (b)(4) of Section 2.790 of the Commission's regulations, the following is furnished for consideration by the Commission in determining j whether the information sought to be withheld from public disclosure should be withheld. l (i) The information sought to be withheld from public disclosure is owned and has been held in confidence by Westinghouse. (ii) The information is of a type customarily held in confidence by Westinghouse and not customarily disclosed to the public. Westinghouse has a rational basis for determining the types of information customarily held in confidence by it and, in that connection, utilizes a system to determine when and whether to hold certain types of information in confidence. The application of that system and the substance of that system constitutes Westinghouse policy and provides the rational basis required. Under that system, information is held in confidence if it falls in one or more of several types, the release of which might result in the loss of an existing or potential competitive advantage, as follows: 2620A

l AW-95-901 l 1 (a) The information reveals the distinguishing aspects of a process (or component, I structure, tool, method, etc.) where prevention of its use by any of Westinghouse's competitors without license from Westinghouse constitutes a competitive economic advantage over other companies. (b) It consists of supporting data, inclading test data, relative to a process (or component, structure, tool, method, etc.), the application of which data secures a competitive economic advantage, e.g., by optimization or improved l marketability. l (c) Its use by a competitor would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, l assurance of quality, or licensing a similar product. (d) It reveals cost or price information, production capacities, budget levels, or commercial strategies of Westinghouse, its customers or suppliers. (e) It reveals aspects of past, present, or future Westinghouse or customer funded development plans and programs of potential commercial value to Westinghouse. I (f) It contains patentable ideas, for which patent protection may be desirable. I I i There are sound policy reasons behind the Westinghouse system which include the follow.ing: (a) The use of such information by Westinghouse gives Westinghouse a competitive advantage over its competitors. It is, therefore, withheld from i disclosure to protect the Westinghouse competitive position. (b) It is information which is marketable in many ways. The extent to which such information is available to competitors diminishes the Westinghouse ability to 26:04 i )

AW-95-901 i sell products and services involving the use of the information. ) i (c) Use by our competitor would put Westinghouse at a competitive disadvantage by reducing his expenditure of resources at our expense. (d) Each component of proprietary information pertinent to a panicular competitive advantage is potentially as valuable as the total competitive advantage. If competitors acquire components of proprietary information, any one compone.c may be the key to the entire puzzle, thereby depriving Westinghouse of a competitive advantage. (e) Unrestricted disclosure would jeopardize the position of prominence of Westinghouse in the world market, and thereby give a market advantage to the competition of those countries. (f) The Westinghouse capacity to invest corporate assets in research and development depends upon the success in obtaining and maintaining a competitive advantage. (iii) The information is being transmitted to the Commission in confidence and, under the provisions of 10CFR Section 2.790, it is to be received in confidence by the Commission. (iv) The information sought to be protected is not available in public sources or available information has not been previously employed in the same original manner or method to the best of our knowledge and belief. (v) Enclosed is Letter NTD-NRC-95-4594, November 10,1995 being transmitted by Westinghouse Electric Corporation (W) letter and Application for Withholding Proprietary Information from Public Disclosure, Brian A. McIntyre (W), to Mr. T. R. Quay, Office of NRR. The proprietary information as submitted for use by Westinghouse Electric Corporation is in response to questions concerning the AP600 plant and the associated design certification application and is expected to be 2620A

. _. ~.. _ _ _..... _ _ _. _. _ _ _ _ _ _ _ _. -. f AW-95-901 ~ t applicable in other licensee submittals in response to cenain NRC requirements for j justification of licensing advanced nuclear power plant designs. f This information is part of that which will enable Westinghouse to: l l l (a) Demonstrate the des.tn and safety of the AP600 Passive Safety Systems. 3 i (b) Establish applicable verification testing methods, f e i (c) Design Advanced Nuclear Power Plants that meet NRC requirements. (d) Establish technical and licensing approaches for the AP600 that will ultimately result in a certified design. .I (e). Assist customers in obtaining NRC approval for futuo plants. l l l Further this information has substantial commercial value as follows: (a) Westinghouse plans to sell the use of similar information to its customers for purposes of meeting NRC requirements for advanced plant licenses. (b) Westinghouse can sell suppon and defense of the technology to its customers in the licensing process. Public disclosure of this proprietary information is likely to cause substantial harm to the competitive position of Westinghouse because it would enhance the ability of I competitors to provide similar advanced nuclear power designs and licensing defense services for commercial power reactors without commensurate expenses. Also, public disclosure of the information would enable others to use the information to meet NRC requirements for licensing documentation without purchasing the right to use the information. l 2620A

i AW-95-901 i ( The development of the technology described in part by the information is the result of applying the results of many years of experience in an intensive Westinghouse effort - and the expenditure of a considerable sum of money, i i i In order for competitors of Westinghouse to duplicate this information,'similar j technical programs would h' ve to be performed and a significant manpower effort, -{ a having the requisite talent and experience, would have to be expended for developing f analytical methods and receiving NRC approval for those methods. l I . Further the deponent sayeth not. t i i t i I I h t s t l 2620A

Attachment A to NTD-NRC-95-4594 Enclosed Responses to NRC Requests for Additional Information Re: WCOBRA/ TRAC Computer Code 440353 440356 Re: NOTRUMP Computer Code 440325 440435 (contains Westinghouse proprietary information) 440437 440465 440469 440472 440484 440505 (contains Westinghouse proprietary information) Re: AP600 OSU Test Facility 480214. 480215 480222 480244 480245 480252 480253 480254 480255 480256 480257 480259 480263 480264 480265 480266 480271 to Westinghouse Letter NTD-NRC-95-4594 (Non proprietary copy of Enclosure 1)

NRC REQUEST FOR ADDITIONAL INFORMATION me Question 440.325 Re: WCAP-14206 (NOTRUMP CAD) On page I-8, the PIRT for AP600 is identified in Table 1 1. This PIRT omits several key component phenomena. Please see the attached Table for a more thorough listing of the PIRT for AP600 Key components that are missing include: Component o Downcomer/ lower plenum o Makeup / letdown o Upper head / upper plenum o Cold legs o Sump o Containment (Interior and Exterior) In addition to very limited PIRT listing, key phenomenological behavior are also missing for the majority of the components given in Table 1-1. Please see the attached Table for further identificanon of key phenomenological behaviors. la. Please include these additional PIRT items or explain and justify why they were omined from Table 1-1. Ib. Also, please explain why the time phase in Table 1-1 omits the long term phase after IRWST injection when the sump is of parucular importance Again, see the anached Table for P!RT information regarding the long-term sump recirculation. A thorough explananon for each of the PIRT items is also desued. For example, a very short discussion of noncondensible gas effects from the accumulators is given on Page I 10, where it is stated that a noncondensible gas model is being consadered for AP600 As noted in the art =ci=wi Table, noncondensible gas phenomena affect many of the components in AP600, parucularly in regard to heat transfa degradanon and disruption of natural circulation which was not discussed. Tl:e lack of a noacandannible gas model is considered a major shoncoming of the NOTRUMP code since it is considered essential for predacnon of AP600 performance following small breaks Ic. If a paacandannihte gas model is not included in NOTRUMP please provide assessments with an alternate methodology coetauung a haible gas model to either I) justify an alternate means to capture noncoedeamble e5ects, or 2) show noacandmaaible e5ects are not imponent. Multi-dsmensional e5eces can occur in the &,w- = core, pienums, CMTs, and IRWST. Without a multi dimensional madal

==nal==== of multiammanional e5ects with a one-D model may not be adequately simulated with specuhzed nadahneiana Id. If a multi-dimensional model is not included in NOTRUMP, please explain and justify its caussaos for the above components. M0.325-1

- -. - - _ ~ _ _ _. - - j i i i e NRC REQUEST FOR ADDITIONAL INFORMATION yi~ii l A P eg

Response

The small-break LOCA PIRT has been evolving from the initial PIRT which was included in the NOTRUMP CAD to the PIRT given in the NOTRUMP OSU and SPES preliminary validation reports. The additional PIRT components that were identified in the RAI which were applicable, were included in the NOTRUMP preliminary validation reports. Westinghouse has separated the transient into a small-break transient and the long term cooling portion of the transient. The small-break LOCA transient ends with stable IRWST injection. After that period, the transient becomes a long term cooling transient. Therefore, the contamment and sump components are not included in a small-break LOCA PIRT since the containment acts as a boundary condition for the calculation, and the small-break portion of the calculation is over before the sump harn== an active comm The PIRT table attached to RAI 440.325 also included severn! different phenomena for consideration as requested in the RAI. This PIRT, designated as the NRC PIRT, is attached as Table I from the RAL The table includes several different transients in addition to the small-break LOCA transient which was the focus of the CAD. In addition, the transients which are listed across the top of the table such as " MSLB with ADS" and others are beyond design basis accidents, or are accidents which are not classified as small-break LOCA transients. The inclusion of these additional transients increases the number of Wa and the number of components that would have to be examined if the table was only focused on the small-break LOCA. Table I from the RAI has been retyped as Table 2 with only the small-break LOCA pornoa of the table retained. Also, since the conemament acts only as a boundary condition, those phenomena which were raan=====* related were not included in the revised table (Table 2). Table 2 can now be compared to the PIRT presensed in the SPES-2 prelinunary vahdanon report (1) which is given as Table 3. Comparing these two tables indacases that there are more similarities then differences, however, the NRC P!RT table (Table 2) lists additional p-m as compared to the Westinghouse PIRT. One phenomenon which appears on the NRC PIRT(Table 2)is the effects of non-condensible gases on the thennal-hydraulic performance of the different coenponents Non-condensible gases did appear on the Westinghouse PIRT as part of the ACCUMULATOR campaaa=* since this was the source of the ace-condensible gases rather than each individual component. 1he effects of the presence of non ea-a

haa gases has been assessed in the SPES-2 (Reference 440.325-2) and OSU (Reference 440.325-3) Test Analysis (TAR) reports for the small-break LOCA transients which were simulased in these facilities. The are==d=aar assages discharge at the end of accumulator injecnoe was simulased in these experuneess, and the aisogon was discharged into the simulased reactor vessel through the DVI lines.

The time period when the Nicopea discharge occurs is of imponance in the AP600 design. For the small-break LOCA transient, the iaisial ', 9 is caused by the break, them as the CMTs drais, the ADS is activated and the rencear system ", __A below the accumulasor set-point pressure of 700 psia. The accumulators are typically empty and discherps enregos at presswas in the range of 100 pois as seen in the SPES tests. At the time that the nitrogen (air in SPES-2) is insecung, the stages of ADS l 3 either have opened or are in the process of opening. The ADS l 3 them becomes the mais energy reisese path and the PRHR h=ca=== less important. The SPES-2 TAR, Reference 440.325-2 Pages 4.41 to 4.4 3 discusses the PRHR heat transfer and i=heasa= that once the larger ADS l 3 valves opes, the heat removal from the PRHR sigaaficandy decreases This PRHR energy removal decrease occurs before the air from the accuandaeors is injected. There is evidence from some of the SPES tests that the air does reach the cold leg belance line and is collected in the CMTs. This poses ao problem since M0.325-2 YN l

NRC REQUEST FOR ADDmONAL INFORMATION lM the presence of air would reduce any condensation in the CMTs and would allow them to drain more freely. Air is also believed to reach the PRHR, but it appears to only have a secondary effect on the PRHR performance. Again, this occurs at a time when the energy removal from the PRHR is small relative to the larger break caused by the ADS stages 13. The analysis of the OSU tests indicate that the effects of the nitrogen from the accumulators can not be detected in the experiment, see Reference (3), pages 6.1.4-1 to 6.1.4-2. The levels in the vessel were higher in the OSU tests such that the majority of the nitrogen was believed to be forced out the break. There was no evidence of the nitrogen in tb CMTs or affecting the PRHR. Therefore, since the expenmental evidence indicates that the effects of non-condensible gases had little to no effect on the component thermal-hydraulic behavior, the non-condensible phenomena ws dropped from the final P!RT. In the NRC P!RT (Table 2) there are also phenomena which would be of interest if a coupled prunary system calculation and a containment calculation were being performed simultaneously. These include the energy release phenomena as listed under the ADS and break c+-- g --2 ats, as well as the containment and sump response. There are also phenomena which do not refer specifically to the small-break LOCA and are left blank in the small-break LOCA portion of the table. Theac phenomena can be deleted for the small-break LOCA pornon of the transient. These include baron reactivity feedback and moderator feedback for the fuel rod component, condensanon in the pressurizer, steam generator asymmetric behavior, and steam generator energy release and mass fbw. There are also areas where the Westinghouse PIRT is more complete them the NRC PIRT, panicularly in the steam generator area. Also, the Westinghouse PIRT has four time periods while the NRC PIRT has five. The NRC " passive decay heat removal and the CMT draining to ADS actuanon" pened is the same as the Westinghouse PIRT time penod called " natural circulation" during which the pnmary system is in single phase and two-phase natural circulation as the system draans. The natural cuculanon of the CMT and the PRHR is also considered during this j time penod Therefore, combining these two time penods and the remaining NRC ph=aa==== and the Westinghouse PIRT, a final PIRT can be developed for the AP600 small-break LOCA winch coetains the key aspects of both I original PIRTS. The final PIRT is given in Table 4. Also included in the final PIRT are the specific thermal /hydraube g'---- ~ ideenfied in the CMT separane effects tests and the ADS tests. The phenomena in the PIRT capeme both the NRC and the Westij o identified ;'--- --- 1he ranlungs of the i'----- = done by Westinghouse are not significantly d:Norest then the rankings used by the NRC. Those specific items wiuch pensa to the AP600 Small-break LOCA have base added to the final Westinghouse small break LOCA PIRT as given in Table 4. The long tenn coohng pornos of the NRC PIRT has been dropped since it does not duectly portana to the small-break LOCA pornos of the tramaient and the review of the NOTRUMP Code Appbcabably na-sinos NOTRUMP is not used for the long tena coohag calculanons. NOTRUMP does not have a son.condensible gas model, although the heat tressfer could be degraded to account for the noemd===shan effects if moeded. The above discussion sadicaned that the effects of non condensible gases were not obearved in the SPES and OSU expenments. Also, the timaag of the gas release froen the accumulators is imponant since the ses is released aher the lager ADS l 3 valves open and the more rapid depressunsanon has begun. Once the larger ADS valves opea, the mais energy sensene path is from the ADS and the energy release from the PRHR decreases This was observed in the SPES and OSU exponesets. Therefore, the effects of non-440.325-3

l NRC REQUEST FOR ADDITIONAL. INFORMATION condensibles are not significant for the AP600 system performance and do not need to be modeled in the NOTRUMP code. The small-break LOCA transient is a quasi-steady state transient which occurs over hundreds to thousands of seconds as compared to a large break LOCA transient which lasts only 100 to 200 seconds. The dynamic effects in a small-break are significantly reduced from the large break since the reactor system is slowly draining out the break while the flows are circulating due to natural circulation and the core is a boiling pot. Therefore, since strong flows and pressure forces do not exist, and since the majority of the system is at the saturation temperature there is no need i for three-dimensional modeling in the primary system. For areas where strong temperature gradients can exist such as in the CMTs and IRWST, one-dimensional modeling is adequate. The CMT test data (4) shows that the CMT will axially stratify. The PRHR tests also indicate that the IRWST will also axially stratify such that one-dimensional modeling is adequate. SSAR Revision: NONE

References:

440.325-1 Meyer P. E., Graziosi, G., Gonzalas, J., Kester, D. A., Saunders, S. E., and L E. Hochreiter. "NO1 RUMP Preliminary Validation Report for SPES-2 Tests," PXS-GSR.002, (July 1995) 440.325-2 Cunningham, J. P., Friend, M. T., Hochreiter, L E., Hundal, R., Merritt, V., Ogrinsh, M., and R. F. Wright, "AP600 SPES-2 Test Analysis Report," WCAP 14254, (May 1995) 440.325-3 Andreychek, T. S., Chismar, S. A., Delose. F., Fanto, S. V., Fittante, R. L. Prepoli, C., Friend, M. T., Haberstroh, R. C., Hochreiter L. E., Morrison, W. R., Ogrinsh, M., Peters, F. E., Wright, R. F., and H. C. Yeh, "AP600 tow Pressure Integral Systems Tests at Oregon Stase University Test Analysis Report," WCAP-14292, (September 1995) 440.325-4 Cunningham, J. P., Haberstroh, R. C., Hochreiter, L E., and R. F. Wright, "AP600 Core Makeup Tank Test Analysis," WCAP 14215 (December 1994) M0.325-4

i ,t( !ji 1;{ 5 H H M L M M L M L L M SD 4 H M H H M M M M L M L L L L M L A h it 3 M H M H L M H L L L L w R T G 2 H H M H H L L L L M S 1 H M M H SDA 2 H H M H L L L u ba R T H M M H 1 G S 5 H H M L L L M SD 4 H M H H M M L L L M L A tW lw 3 M L B LS 2 L M L L e t 1 H L H M L H M L L SD E A 2 L M L L e B pa 1A t T ELT SR B At L P 1 H L H M L H M L L T N C R I N 5 H H M L M M L L L M 4 H M H H M M H M H M L M M L M L A C O 3 M L H H L M H L L L L S S 2 H H L H L L L L 1 L H L en ie s s e o m m e e p e e s e h t y s s s n e o e e a e s p e y e c c t n c c g c n s n s e o s e s s s A g e o A A m o e e n a m A A n e ,n e s e e t e e t e l l e y e o o e y m e r e s e g e e r e e s e n l t g d m y e t n s o o k e. l i c e h s a n t o o b n s t o y o e s e c m n a o m e W e n a g l s n e m I. n e r P n e o l s n o o n M e r e n s m o a n n s m w e n t n t e e u t r s e s w e s e i e i y d e s d e y d c o u d t o le e s s o n t e m g a o n y e t n n g s n d d n e a t n s w ns g a e o r o d f o s o e a s o M g s o d f N p c 4 e e w p s c e a w n o s w s n n e e a o o h n o a o o e m n L s s s n r s o a o o o a o O o o o o o o t t M N S F N E M R M C E R M N C R L N P S C R R L l a %D e gn I k C S e d e e l r r o o 1 A 3 C C l f lj l' l l I

t' l ,i! I I

2 i

l' l r i 5 H M H H M M S D 4 H L H L L L L L L H L M M u A 3g h t L M L H L L L M H i w R 2m T H M M L M L H L G S m H L 1 m SDA 2 M L M M L L H L o du R T G H L 1 S 5 H M H H M M 4mH S L H L L L L L H L M M u DA h 3m it L L L H L L H w a 2M se M M L L M L L H m a M L L L M L M M H M L 1 sD E A 2 M L L M L L L H L o B d 1A a E T LT M BI B W A P L M L L L M L L M H L L 1 T S C M R ID 5 H M H H M M 4MH L H L L L L L H L M M u AC 3M O L L L H L M M L H LSS 2 H M M M M L H L m H L 1 yesned h l s c e l e t s e a e t e s e n e e d c e s s e r c e u e e r a n e l i l o e h t e w s e s e s n o e d o l e s e s e y s o p s a i s s a a i l e o e A e h M e e c n y e o r r c p n a s h c o m s h m n n t m n s e e y e n t l e m y n o e g h f e g e s e o u n s p e i e r I s t r r P e o d t i e s n e n e c e r e r n m o n s u E n e n e s o n u o s s t y d e e o c n, t d e g s s n am e 4 a e a e t l h g n r n e n a g n s n e e o d n e n p p n a e r d i e s o m t e T d N ed N t M., e e L n l l r e y c e o f e r e c o F u s d k n s u n s u a o h o o e o v c n s s n e l r u o M o e o o o s r o o C o t e e o e a t T V C C R R L N T V C R R L L M S B C C M S C C E res e sA sen e n d e o e g s R e n r f w e t l d fa o s e a C D F H ll l

l [ m 5e M H M M M L M n u S 4mM M t H L M M L L M M M D m A m h 3mL it M L M L L M H w R 2mM T y L M M L L M H M M G S m H H H H 1 mM SDA M L M M L L M M H M M 2 o / w R T G H H H H 1 S 5M M H M M M L M 4MM S M L H L M M L L M M M M DA h i 3ML t w M L L M L L M M M B 2M LS M M M M L L M M M M MM M L L M L M M 1 SD E A 2 M M M M L L M M L M L o B An 1 A u T E LT BR B At L P 1 M M L L M L M M T S C AR R N 5 M H M M M L M 4 M M L H L M M L L M M M M A'C 3ML O M L M L L M M LSS 2 L L L M M L L M M M L 1. H H n e o S t t a i t s n n e rn h e B e u o h e 2 o s g e c eb e n A m e m o e n c t n o r e W g h n N kM e u n e n t a m e e n to se eD o c d u mr o r w r o s y e o o t ef e n t s t n r a )y r n d t t A gP r e c o s e t e y e e l n nh n c G e n e r E a e k a p o e s u n e g h l r r t c n m u s w e 5 P l n o p e t n is s o e o v e a y d s n o s i le a e n s n e e g de s r r i e g p I s n w r 7 u t t nd w r o l n n g r u e t e o oe m d L N w (l le o e o e d n ie as n r li o s t l t t r o s e a d w to p ei u r l t l s l t e r n F e a v v t n a r io e o s s os g o e o o on o t t o o oe o o o C e e e e o a h t l ae l n P P Pt P N C C F H L L r l H N P S V D F i c r F I l mT mg 2-re o s - m ur mt e o e S g M s e y r W e p

i i ,{ l l i! t' [ l l I t

i!t 5m L

L L L 4mL S L L L L M L L L L L DA 3w h t M M M H M M L L H M M H H M i w R 2ML T M M M H M M L L L H M M H H M G S ML L H H M M M 1 eML SDA 2 M M M H M M L L L H M M N H M R T 1 L L H H M M M G S 5M L L 4ML S L L L L M D 'L_L L A j 3M e i M M H M M L M M M L L M w S 2MM LB M M M H V M L M M M L L M A B MM M M M M M M H L L H 1 SD E A 2 - M M M M M H M M L M M M L L M L o B d 1 A u T ELT BR E AI L M M M M M M M H L L H P 1 T S C M RN 5M L L 4 L L L L L M L L L AC 3M O M M M H M M L L M L M M LSSl 2M M M M H M M L L L H L M M M H H 1 IWt h W ta f s e s e P s e e c e s h s t e r n m n h e o e c t a r c y s u n e e a i t o t s r o e en A e s s s I n w n r A a t s e d w s e M U u s e l m e n o o r d c v e e w a e e h n s e e p e e e e o t e s e e h e o e s i l n t c b i m t s l o m u o o e o t y b r s o b o n a e a s p n b n e s e n r h e g e o i p y J g s l l o s e l l e d T n e n c s n s n n a P n e c s W s e e e o y y g s e e t a l e5 e p o n a s e m e r s s a e s k d n t nW d s d o p e s e g te s s d t e n n n yr d d n e e n e e e n s n n e n sW n g n w s e e o r e o d r e e s r n d c ae n n e o e n s o r c e o d s r N W c s d e c e s o o s V V n p n e a s sd n a y n n mn c c n b n f s u e a o W o e en o h o ie e e R R u o e l o s o o o t r N S V C D R R Ha N P V P R A C N Ps S S S S T N P l l mP [ ( e r r ^ o e t e a s r r e e n n e e) g g nW e h t C g p em s u s m s f e et P

,ll lll ll m m 5u M M M M H M M M H M m n S u D 4u M M L L L M M L A m h s i 3m L t w um R T e G 2m M M L m S a u 1 mm uu S m D m A m 2m M M L M M H M o / m w u m R T 1 G S ~ s s 5u M M M M H M M H M m 4-S M M L L M M L DA ith u 3m M L L L L w m u B L m SM 2m M M L L L L m H M M H H H M H M u M L M L L M L 1 e S m D m E A 2m u M M M M H M L o m B pu m 1 A 1s u T n ELT u BR B m AI L m T S 1mH M M H H H M H M M M L M L L M L P C M mu R s N a 5m M M M M H M M H M un m 4u M M L L - M M L n A u C i O n L 3u L 8 m S mu 2m L L L m u m u 1 um r r e e t t ) n l a 4,- ) s i o o a s e p e a s t n s h o d m a s g o e c e e t r o n y d e = d n m. e s e o r t l a e a e r e N r s e r t Wd a e s p p a t = a m d e c e a m s e n p d e o n h m e r r y e r n h l n s n e A o e e r o a n o e s e m e v p s y c n e e n n G a o e o c o m e e e ( w n g o o o n h s h r t e c t m w a s y a e o r r S s u P r e o e n n e a e o e i o ( e o n e s m y n o s e p s s t S m 0 n y a g e s t s ( g s e n n E %s n n o e a c r r e e ie N r s e d r m e e o e m n d h g M N d d w p e, o s t e e e e s o v t p s r u e n d n n e r n a k w c o )e v a o o e p 4 i e o e a o o o s e h o r n o u k e t R n L g V v C C n w T v E Ra L T L D n i n m-r )r r e e e t e a syr t r r eI ed n n nr e s e ee m) g gn im n ,m a 2 m mer s ,u W e C n e ep n ,e e n s e ,i n e SI s (e C yP I

.I I ll I1lllll l \\ 5mM M M M M M M M M M H M M M M M M 4eL S L L L L M L L L L M L M L L L L DA 3g h t iw R 2m T G S m 1 mM SDA M M M M M M M M M H M M M M M M 2 e m R T 1 GS 5mM M M M M M M M M M H M M M M M M 4mL S L L L L M L L L L M L M L L L L DA h 3mL h L L L L L L L w B 2mL LS L L L L L L L tb 1 L L L L L M L L MM SD E A 2 M M M M M M M M M H M M M M M M LB W 1 A s E T LT BR a AIP 1 L L L L L M L L a T s C am RN 5MM M M M M M M M M M H M M M M M M 4 L L L L L M L L L L M L M L L L L AC O 3 LO S 2 W 1 re f t 0 s a n n n e e a h o s t i 6 r a m e t s v e g e e e r e e d n d ie p e o c e r h e f e s o w n s n S i s s i t p e m e k en n r w o a o e e t o e e r r d e d c t n c d e d is n o d i t t g e e t o t o e m e a s e W r h r n u e w s s s c c S a r n n i e e o e n n n o n t h P r e o t u e h o e a e d o r m t c d o d n h y g w w nr n Wm n w w p e r l mo e n o e e o m wa a S S S St d t d w o m e c s c s C C C Cn e t n ns n n 4 e s r r N s s C C C Ce o o on a a e i a L N N Ne N P S A A C E P P P Pt 2 1 tne m e n ia e tnoC

I l t' j i; 11] l:!!l l llii 5 H H u L M M L L L M 4 H M H H u M H M H M L M M L M L A C O 3 M L H H L M H L L L L8S 2 H H L H L L L t ,I 1 L H L D E S IVE R EL B 2A E T LT BR e AO n P T e A ms n C o o s O n m L e e S h re S P o p e s C M e R s e s o N m e e e o p o s o h t y n o o e o a t p e c b a t t t c c c g c s c c a o e e o a e g e s s e N m m A A N o e c e s n s es n e e t e e t i a e y e ig d s e g o r d g t c e d t w m o n s e o o e 0 y m e e r o s e r o d t t t a t e c e n a n e a o y t a e n t o e n e g e n n l s o m sn d r n a m e o a, n D o s e e w s o h tg t n G n is t n m e ts m e o n n le s o l w o s r e e d n. n e u y d a y d r o e d r is o d e g s d M h r r e g g n y n e n m r e S n n n a d c i e a n n o n o d m r o r o o o o g s c M g o c d N N t p s c e e e o u s n r p c c r x w n s e w n e e w n n n s e s o n L so o s o d o o n s o o l n o o o o e o o O o o o a o t t t o R N E u R M O E R M N C R L N P S C R R L M N s S _c ega t t s s a d e o e e s r e a A B C C } l l l

-w w,---- 4 m I 2 I I 2 2 W O O O A N I 2 2 2 2 J I .a e I a n u l, l i i i 1 l i ll ] l !il l i l lul i ! ll !! !lIlsl l i l i j i i i a i 8 3 3

l e 2 I 2 2 2 J 2 2 a I J 2 2 J J 2 2 2 2 a a n 2 a 2 J J 2 2 2 2 2 e I I I I i i i i I l gj 1 lf i I 5 I l l l hl ii i b i nl 1 1 1 1 ] II l l o 1 1 z r i ll s I l l l l l i ( l 1

h i l l ,I.j i p L L 5 m L L L M L L L 4 mM ACO 3 M M H M M L t M L M M B L S ~ 2 M M M H M M L L L H L M M 1 H DE S I V E H E. l B 2A E T LT BR e AM n T T e S A m W C o O n R I L e r r S h d e e f f S P n s s a n n a a C R r r R t t M .e h W t t N a e e. ) f s e s e e p P e s c e h o d h n a n c e n e o e y d y r e o a l o 4 r e s a a r e S h n d s o p y t g a e r et a e i d e n u u d w n y s e n o n h d m s n n e s p n e e e o d s h h s o e e l o g a n s m o w e o o o b t s e o e c v s o t o e m e s p n b n n e w o n r l o d a e s o e l t n a n ic s n n s e n s s s t m o y y W s e o e e s o d e s s s s e p s r s r r s e n d e ie t t ( i s n m a a e e o n e e e le g e n s s e e n e r % s e n n y d d n n v o s n n e n t o e n s, e g n g n n ia re n n e s e e m N c s e n d r s d o o V V e c e r t r m c c o u s a n a n t c u y n n e t e e R R d o e c-o W o e e o h a h io n l o s o lu C D R F H N P V e R A C l P s S S S T N P r T v E "z_ )y r an krp ( C s e r r s e e s e e e s s r r r e e e 3, n n n m= e e e g g g ep m m I W e e a e W s m s s O i a n s P P S e s c ll lI, l' jl ,ll,

=. - -.. 1 I e - '2 2 2 2 I e 2 2 a l" ^ \\ a a a i 1 "!!i il I I l l l li'l l I ll t I lul i n i n n i } l i I I

i.!!

t

'l ) f! ,i, ft no itcg e n gi A A / L M M H W I so M M M M M L H L L L M M M r N T o SC WR I n w So A A A A d N N M M M H N M M M M M M A Dw H N H H H H / C Ao s O e L KA E H8-LLAM ) S S 0 D 0 A G n t l e PA ae n s e r e A A A A A A A A t R ue H N e WWN MNM M H M M L M M M H r / t u N O a c v F Nr d i e E C 6n L ( B A H T GN G 3i E M L A BR A N ) T O S I D T A A n C w n t IF o e A t A A A I d H H M M M M H M M M L L L L r N w W WNW T ev o d E s D e u I k( A N H EMONEHP ESUOH r G o s N o I n T e S sT E t W soH y n p d w e tne p e n n a e e en b e D s w e G ne e WP v l E om D e o r e R a po e m l t v F mn o y e e n r o e u n n g n s e L o s o a C h r e a c d a r mn t i s r e e g M n d e P e u c n a a h H p u w r e E d l n F ee a a n n o P P WH v n e wl w t n d n v n v r d n l l e e uo P P o F o s I e o e e o o e s s t l l C L r r s c C g n o d o o r r s 3F a o F i e t e e n h L S P u S gw s p y d n e le s se o ol a P a o N s s n s i c e c e t we s % c o e s k e P e 8 n m1 e o h C S sC T V S mD F F WN e C e e Se A s e a a s i ea w e e t e o d h R .P W rP e o ,u r l r e e e o mo g m c a n e H a i I w w c L S ts s e n e r M S e P e s u p d s l D e C .e e o p o v A V R P P D U C l t !l l il l i ll l l l l Il ll l !l l l

t

i ii

!l'l l j,f [!

!i!'): i '

l ts i III I!i a n To-Si-A t Wc-L L L H H H L L L L L / L H L M L Rf N e-I n c. I )H ( hgu t s hL a A d C S A e L L H H L L H M H H H L /M M M O D k N n L A a r K e A b ER d 4 luo L w LA en At e S m 0 o 0 n e e r hp A n l e S R ad D O r e A A A A A A ul MMM H N W M MM H H M/ N WN M H e F t u / a c E Nr D i L i B C e. A s T ac G te N i 0 N 31 E0 in 0 L A S; SR D AN A T O t I n T oe hL Nt A s e e C c v R A A A A A A A A ud WW M WW M M L L L N W MN M L pa f f I pn TN Ai n E t D oo Ne I A l t N Ane E Wia It n 0 ser 0 ot 8 n E aie H s ts P o s pe E no S id U wirs O a s H L e r G e - m f e e L. h e w n p T e e S s ce E T nn t t eo W n a g t riS re e e e n H rg vh d g s e nn n s d e i l l e e n o s e s e a ed n T n t e n t r i e e s o e u ed n t n e R E S R o oe s o o o o n c c l m o n e a e n e o F dn R e i hD e H o a e t e n e t l oo e s n Mp G s o n c u t e eR n o e u l a r i o s e c t g e e g m s n s t p a / e o T r u a t n n p t i e d. e n o e h e r M, P C u r s d e e e C m e n u t s r t d l l e m e F e e n D c m s n u n e s n s e e o e a o F c s D o s e l m G 1 d D e C n o o e o e d C nw c on n n y s r e l e r oN m P t s s o ue o l r m e t t ua G c t r t s e e s t s s s o s u o c a-e m W m ic e p es o o a e u c e pn e n e p e u h r m I e0 e o o e a co t a u a s s e uo n2 S R C S R G V nP R N G V P f I t s s e a @S G s g 4 s s D m o 1 a T h A M J L 8 I a S R n !l1 ll;l l l l il l I ( jI l BHT e W w I D P e t D h I t o D A a V f R S H A C C l

I g !( { f l! i ]jl lt tl Tongn Sei A A A A A L L L L L M M LNL L L L H WL M M H L L Wc o l NL NL M Rko nC I i n w So A A A d H H H N H L M LH L L H L L H H N H W MM M H L L M Dw Ao lB )S A D C A n O e t l L at n s e 8 rul A A A A A A A A A A A A A A e t WWN NN N NH N M M N NH H L H MMW MH ML N r S t u e a c v 0 Nr d 0 i a G C P in ( A R H O F 4 T EIW L P BAL ) TA SD 6W A F %d tn E e S t A A A A A A A A A A A A A A A WWW WW W WH W M WW WW WM H MMMMH ML W r U e O v H a G W in e ( T S H E W em s os o n c ) a a t s r r e T u n l o t t t s n a e i e e le n H s s e e s m o n y e s s o G ln d r a p o e n o M n p t o o D p g a n . e n n e s e d D e . d E s w e sWe e v t et o o n d P s g n e e n F o t l i l n e n e e e e e y e ru s u o t t e s c n g n s G T l n e o e s c a e r o o n m R e eo R m s v s e n e so e m M c e o P c r s t e s n e w e nS o o wt L e y e E d n c n s s l P P e o p o g v e a o e s w s wl ewl C o e d o s t n d o v n mg s s a o F e ao F l n l p e a t e wte 3o p o e a Ea e F o o - l o e h e n e c s t l l C L o s s F i e sF c d g CS E H C g n l e gn s 1 F e e P g n i h L d n h e n r n n eF R n e s c N e d ey d n e l o

l l

a P o e o g Ra o a e N S e o e m s a e hd

c e

l t s c s h s e s a s r s o c e g n i e o o n oe o w g n e o ea es c s L a s s s u c s n go c n o ce ol f i s e s e e o r ol w e k 4e w nl o B h t r o N n e a n e eRP P S sD F F WN M MF DC l a SC T V S 1 C S T LC S D L t s k d s T s S e w l e M D D e o e s C v C A A e ll ll l t l l ,l l ljlll lfl lff(

ll ng To i / Sin A A A A A A A A A A A A A A A t Rbo WM w N WN W N WN N H L L We lo g uW M M NMH H L nC B I n w So A A A A Dw M H H H WN M M H H L H L L L M L M M ML L d N M Ao lB AC n O o l L ai t B r a A A A A A ul L S t u W N H H H L M H H N M M L L L L M M W M M N M a c 0 Nr 0 i 6 C PA R O F 4 T ER LI B P AL TAN IF n E w S o A A A A A A A A A A A U d L L H H W L MM W MML W MM WL NWW L L O w W W o H t G S ew TSEW it n ez w io e T g te s T e M to M R ke C o i n C e e S w m e d c t d n un ( a no g a. B s %r o c o l e e R t t e e a M ru c s m n n n f ) e e n w e d y io P r r r d a e e e d g n ta a b n a e i f o l R n n e w n o L c, d o r-e n oG g C d r e T u d 2._ e n n g p o u wM c d e i l i p a n n l t mT C j F e i i

o M

n k m a e T n ( t r c s n C o m d n M e s e T C h h n e n M e C e e e r e g D - _e d e l n r e T i e o e. a C e t e n P m e m h e h o f n s t s i g e n t n f L n u e w m i s e o e s e n o h e e l o y a m o n E s s f s c n on er nC o e f l r s S n e l e y R F o F e s u e s e me o D d g e t f l r e sp e y n i s e p u hh e d d t d e a s o P t t n n t s e mg e h n n m i n n cn sw r d g i n e r eo r o o e o = a n s e F e L e s , s e e t t lc )t Nc r T a n n p T ie u t w ms uO % s. g c e e c l n d sM ee d n u e r r s E t mg i e e e m d d s e S g d v D o s y n e e c e dd in aC d n g e e C l e n n n r n e i s ad n m u C An A d e i N m s d wl p s an ma o e e a L r e p e n e r. o m=de Md N e eN e* r e r 6 n i o t i n T n w ms w o o e u n r e ao r r r e l e rye l e a o n w h *w e ep e Mr o e e e e o h es o o go f l y oe e s l ol a o t r e l e n F C aP F oF L L S aC E F H P TD F P C v a n Dt RN id T T < T r m L S W u t M M o o C C D H R I ( (( ( ((( ff( ff((

'(

e ,I l' >l Tong Sl in A A A A A A A A A A A A A A A A A A A A A A a Wco M w WMwwww Mw WNNNwWw wwWW MM H M l Rko nC I I m u So A A A A A A d M M M M MM L L M M ML L w MMNW ML L L M M H M DAo lB A C n O ie L el e O wle A A A A A A M N WW M L L L L M MM L M M M M M W M M N H L N S u to 0 Ncr 0 i G C PA R O F 4 T ER LI P BAL TAN R %M ES A A A A A A L L M ML L L ML M MW M L L H M N NH M M L U W OHGN ITSEW n e ) ne e r 0 en c e n om e s in ne n t o n n s e mR n ie e r h po s e s a e s t mn d T D n e s e o e e e F e n d e d C h R r s s m e n n b n e s e o a e t a e H o e e u o e m P w e u d s s wT C G o n ra l a h e es e r r r e o r F o R s o o ) e e n o e e d Rna s m ( y r t n n v o o e s c l s a ip Ora e e o l t e r p o y i r s r e e s g e ee rd e e C d L P e n n n n e t v o n r c n n e e e o r a eD oe n y o y y e e e T T d g wE e l D e e n r e we wE p w o s r r r r L G a C a a G n e t d d ug D g o e a ms g ir t S S s wg e o d d d a a o r a ei h e r n n t u enN mn e n n m e e C d r r s r c N le e e o ee o e L s n h aF a a o eo o a H H nic e o a a l r t s h s s v w n p s c c c e NP wC e r ise o G$ r t e Me e t o t o e H e C e aM R D R M t e o e a r r L L S V wP R m2 S S L S S S t R r e e e n o e H p m e h R p e rP P S P u l (.l t l l l l [ fl l lllll llll[ (

--,,4 a.__, .,m 5 h$h~1' i -lII~ = i l P i ilu a

i' l 3 i l i l NRC REQUEST FOR ADDITIONAL INFORMATION l i l Ouestion 440.353 Re: WCAP-14171 (WCOBRA/IRAC CAD) j Once the accumulator empties. AP600 will depend on hydrostatic forces for further ECC makeup flow. There may i be problems with core makeup tank (CMT) draining due to interference by condensation-related effects. Condensation { of steam flowing in from the cold leg /CMT pressure balance line (PBL) will occur on the cold CMT water. This j condensation may affect CMT draining; therefore, accurate modeling of interphase heat and mass transfer is crucial to the successful prediction of CMT injection. Describe the tests thst will be or were used to assess this phenomena l as it applies to CMT draining. Provide comparisons between the test data and WCOBRA/IRAC calculations to demonstrate the code is capable of correctly modeling CMT draining in the presence of condensation. Response- ) l 'the condensation of balance line steam is a significant factor in determining the rate of flow of water out of the CMTs. For this reason, testing was g.h.ed at the Core Makeup Tank test facility as reported in Reference i 440.353-1. In the 300 series tests, a 1/6th diameter scale CMT was tested for large break LOCA conditions in which j water was allowed to drain from the bouom of the tank while steam flowed into the top of the tank. The steam i replaced the volume of the draining water; some steam coada==ad on the cold surface of the water, and some l condensed on the cold wall. 'the 300 series tests have been modelled by WCOBRA/ TRAC, as reported in Reference 440.353-2, and the compensons to the test data are provided in that document.. Acceptable agreement for drain rates l fmm the CMT were obtained for the 300 series tests by the appropriate selecnon of the noding sizes in the CMT. This noding approach has been applied when performing the AP600 Pratimsmary SSAR large break LOCA and long-l term cooling calculanons with WCOBRAfrRAC (Refersuce 440.353-3). Additional jusufication for the CMT j modelling is provided by the modelling of the Oregon Staes University esses (Reference 440.353-4), in which the j same approach to noding the CMT was used and acceptable agreement was obtained for small break LOCA simulanons extending into long Term Cooling. Reference 440.353-2 assesses the CMT drain rate sensitivity to the j heat transfer coefficient assumed at CMT wall sisfaces. Together, References 440.353-2 and 4 demonstrate that ? WCOBRA/ TRAC adequately snodels the steam / water ca=daaeand auxing which occur in the core makeup tanks during the vanous phases of paanilanad LOCAs in the AP600.

References:

A40.353-1 Leonelli K. " Core Makamp Tank Test Data Report". WCAP 14217 (propnetary), November,1994. 440.353-2 Haberemah R C, Hochresser L E and h8a=aha= E M. "WCOBRA/lRAC Core Makeup Tank Preliminary validados Raport",MT 01 GSR003, February,1995. 440.353-3 Lamar NTD-NRC-95-4480, " Preliminary Marked Up Secnoes of SSAR Chapest 15 Revision 5", June 2, 1995 440.353-4 Chow 5 K at al. "WCOBRAfrRAC OSU Iang Tenn Cochag Prelisunary Validadon Report" LTCT-GSR 003, 6===h= 1995. 1 SSAR Revision: NONE M0.363-1

l I NRC REQUEST FOR ADDITIONAL INFORMATION E= - Question 440.356 Re: WCAP 14171 (WCOBRA/ TRAC CAD) Long term cooling results from gravity drained systems with low driving heads in the presence of competing forces. Long term cooling was not addressed in the WCOBRAfrRAC CQD; therefore, describe the LTC methodology (if it uses WCOBRA/IRAC), describe how the LTC methodology will be verified, and compare WCOBRA/ TRAC results with the assessment data to demonstrate code performance in this area. i

Response

The Long Term Cooling (LTC) phase of the transient begins at the start of the IRWST injection and continues to the end of the transient. The WCOBRA/IRAC methodology for LTC takes into acco sat that the AP600 amall break LOCA and Lit transients can extend for very long time penods (typacally 5 to 24 hours), by which time there is sustained, stable injecnon from the sump into the reactor vessel. Whde long aimulanens are possible with ' WCOBRA/ TRAC, they are not practical due to the extreme computer runnmg times that are necessary. The approach used for the SSAR analysis is to perform the LTC calculanons in a " window" mode. This means that the WCOBRA/ TRAC long term cooling calculation is staned at a gives point dunng the long term transiest with conditions that either come from a previous WCOBRA/!RAC large break LOCA calculanon or from a N(yIRUMP small-break LOCA calculation, or are reasonable aanmanan of the primary system inventory at the time of the calculation. The long term cooling calculation proceeds for appron==a*1y 1000 seconds to verify that the passive safety injecnon system is providing sufficient flow into the reactor vessel, and to show positive liquid flow through the core which precludes baron precipitanoa. i The OSU expenments were used to vahdass WCOBRA/ TRAC for long tonn coohng for both the initial portion of the small break LOCA transsent and the window mode of the long tenn phase of 14CA transients. The approach used in modelling the OSU tests to vahdase the WCOBRAf!RAC LTC methodology (Reference 440.356-1) was two-fold: The small break LOCA penod is modelled with WCOBRA/!RAC so that the initial blowdown, natural circulation, ADS blowdown and early RWST injecnoe ge==a==== of the test are calculated. The simulance of the IRWST early injection phase provides the sopresentative initial conditions to be used in a window mode==alana= for laser phases of the IRWST injectos as well as abs trassence to sump injection. The window enode simulation is a sarise of quasi-equdibrium calculances, using WCOBRAffRAC, over a selected time interval dunas stas overall transsemL The other initial and boundary condidoes reqmrod for the window enode ai=al=aa== which are taken from the test data, are the esmiparasses and weser levels of the senp and IRWST and the core decay power. More dotads of the LTC methodology and its veri 6casion may be found in Reference 440.3561. The objective of the window mode==al=aa= in Reference 440.356 2 is to show that the core man covered during IRWST injeceos. The phdosophy of the window mode approach is that dunas the early part of the window mode simulanoa, the impact of the assumed initial condations decay so that they so longer influsace the predacted M0.366-1

NRC REQUEST FOR ADDITIONAL. INFORMATION m-results when the quasi-equilibrium condition for that window is achieved. The " window" mode calculations examine I times when the passive safety systems are most challenged in terms of maintaining sufficient inventory in the reactor ) vessel such that the core does not heat-up. The first cases examined are the long term cooling behavior following a large-break LOCA. This transient was chosen since the core decay power is the largest when the reactor system j transitions into long term cooling. The first window examines the cooling mode of the core with IRWST injection I after the CMTs have ended injection, which occurs when the decay power is large. The single failure assumption l is one fourth stage ADS valve fails to open. The second window examines the switch-over from IRWST injection j to sump injection. The sump injection has a reduced head of water to drive the flow into the vessel, and the sump liquid is at an elevated temperature The window calculation for the sump injection following the large-break LOCA maximizes the decay power in the core that the sump injection must cool. These two calculations bound most of the small break and large break transients. A third calculation performed in Reference 440.3S2 is initiated based on the NOTRUMP conditions following a small-break LOCA (2 inch cold leg break) in which the IRWST will have heated to a very high (saturated) temperature due to the heat transfer from the PRHR and the ADS. The wtadow mode calculation bounds the sump injection initiation time of this transient and consitutes a bounding case for LTC following a small break LOCA by analyzing non-coincident worst conditions. To validate the WCOBRA/IRAC code for the LTC transient, four dafferent OSU tests were simulated and exanuned. 2 inch CL break test. This is the reference test. SB01 double-ended balance line break test. This is a small break test sinular to but larger than SB01. There SBIO is also asymmeenc CMT behavior. double-ended DVI line break test. Sump injectaos begins early in time when the core decay power is SB12 still high and anaming rases are large. simulated 4 inch breaks at the top and bosom of the CL 3. Rapid blowdown is achieved with early SB21 IRWST and sump injectaos at high core decay powers. The breaks on the top and bosom of the broken CL are similar to a circumferentaal split. These tests capture the thennal hydraube F r-of inearest for small breaks and LTC and vahdate the performance of WCOBRA/IRAC. This work is reponed in Reference 440.3%I.1he window madas selected include the start of sump injeceon; this pened has a low flow raes and a high temperasure in the DVI lines and the highest core power of the sump imiscoom penad. Tbs wmdow anode simulations for tests SB01 SB10 and SB21 start 200 aaraada before the start of sump injecoce and run for (typically) 1000 =anaada In the case of test SB12, the wtadow seleceed is the Saal 1000 seconds of IRWST injecnos. The first 400 secoeds of each simulation are considered to be the pened over which the WCOBRAf!RAC solution is approachang a quasi-equilibritm staae. Average values used for comparinos to the test data are takes froen the penod 400 secoeds after the start of the window until the and of the wadow being sunulated. A PIRT for I.cas Tenn Coohag is given in Reference 440.3%1 and is used as the basis for the aaaa===aan of the OSU predicuoes. The pradraaan are shown to be w ~ A ie. M0.356 2 Y c-- r m sw-

NRC REQUEST FOR ADDmONAL INFORMATION i The containment pressure used in the Reference 440.354-2 analysis is obtained from AP600 WGOTHIC calculations. WGOTHIC is a state-of-the art containment analysis tool which has been equipped with special models of the passive cooling mechanisms applicable to the AP600. The OSU test program results (Reference 440.356-3), the WCOBRA/ TRAC simulations of the OSU tests (Reference 440.3SI) and the SSAR LTC analyses provide confidence that the AP600 passive safety injection systems provide sufficient flow that the core will be safety cooled for an indefinite period following any postulated LOCA esent. References 440.356-1 Chow S K et al, "WCOBRA/IRAC OSU Long Tenn Cooling Preliminary Validauon Report" LTCT-GSR-003 440.356-2 letter h"ID-NRC-95-4503, " Preliminary Marked Up Secuons of SSAR Chapter 15. Revision 5", July 10,1995 440.3 % 3 Dumsday C L et al "AP600 Low Pressure Integral Systems Test at Oregon State University Fmal Dats report", WCAP-14252, May, 1995. SSAR Aevision: NONE uo.sws

NRC REQUEST FOR ADDITIONAL INFORMATION Question 440.435 Re: NOTRUMP ADS PVR (RCS-GSR-003) The flow quality data show an increase in quality within the first six seconds for all of the tests while NOTRUMP displays a decreasing trend. While the flow quality at the sparger discharge will establish the depressurization rate for the system, the miscalculated flow quality, particularly in the beginning of each test, suggests that NOTRUMP is lacking dynamic effects. As such, explain how the two-region fluid model void distribution in the liquid regions is computed, and how this lower region void fraction affects the quality exiting a volume. Also, does the assumption that steam regions form above liquid regions affect the fluid void distribution in the ADS lines? That is, explain the conditions where separation occurs versus highly dispersed liquid-steam mixture conditions with void gradients and how NOTRUMP treats these conditions in the ADS lines. Are void gradients computed in the liquid regions? How is the release of steam from the liquid region computed; is it based on the average void fracnon in the region or is a surface void fraction computed for release calculanons? In vertical sections, during d.i - =-izanon transients or vertical regions with high heat addition, large void gradaents can develop where the surface void fractions can be two to three times greater than the average. Please explain how NOTRUMP treats the void distribution and release of steam from the two-phase regions under these conditions?

Response

The large difference between the NOTRUMP calculated flow quality and the quality calculated from data in the first six seconds is due to the fact that there was a time delay in opening the VIl-1 valve. When the time is adjusted so that the compenson is based on a consistent VU-l valve opening time, the agisement is much better as d%*ad below. Figures 440.435-1 and 440.435-2 show that in ADS Test 240 both the pressure and the mass in the supply tank are constant in the first 3.5 seconds, then decrease after 3.5 seconds This mesas that VLI-I gate valve did not open at time zero, rather it actually opened at 3.5 M. There are many reasona for this. First, the valve was initially very tightly closed. Therefore, when the power was apphed to the gese valve, it took a penod of time before the valve began to move. After the valve began to move, it took additional tiras to clear the seat and actually open sufficiently to allow flow to pass. Because of abe shape of the gate valve, tae valve apeams area did not increase linearly at first, but increased very slowly, then gradually increases haearly increase as can be seen in figure 440.435-

3. This is reflected in the presame plot (Figure 440.435-1) and teses pict (Figure 440.435-2), where the curves j

change gradually, insemed of sharply changing, at 3.5 seconds when the vrJve is opea. In the NOIRUMP sumulation, the valve is assumed to open linearly frem the time aero. To have a comparison between the N0! RUMP e=8aal=*'a== and the data, it is necessary to find the effective opening time of the valve in the test. This is =aaa=TW by interseenas the linear pornos of the presswe curve (Figure 440.435-1) with the l initial hansontal line, which is 3.5 socoeds. Therefore, the compeneoa of Toot 240 in reference 440.4351 should be corrected by shifting the data curves to the left by 3.5 seconds no t'ast abe aceaal VU-l valve openang time is at time zero. The results are shown in Figures 440.435-4 through 440.425-13 (The original unahafted plots in reference 440.435 1 are shown following each shifted plot). It is seen that the agreement between the NOIRUMP calculated quality and the quality calculated from the dass is much booer. A simular time shift is appbcable to other tests. mo.as-i

NRC REQUEST FOR ADDITIONAL INFORMATION In the NOTRUMP model of the ADS tests, the homogeneous fluid model is used for all pipes. The two-region fluid model is used only for the supply tank, and not for pipes. REFERENCE 440.435-1 Yeh, H. C. and L. E. Hochreiter. AP600 NOTRUMP Automatic Depressurization System Preliminary Validation Report. Westinghouse Electric Corporation, RCS-GSR-003,1995. 440.435-2 Final Data Report for ADS Phase B1 Tests, WCAP-14324. April,1995. SSAR Revision: NONE 440.436-2 Y

A, m. _a_- a.A...mm_.Ad ,mF ,_w.maAma .4 4 .m w e. e m a swm.,,A4-u_m.w.._a .g e -. -.. --au 1 1 i ) NRC REQUEST FOR ADDmONAL INFORMATION i 1 l i me h b s. b. 5 i, 4 i 4 4 = = Mgure 440.4351 Supply Tank Pnesum. mo.4ss-3

) l NRC REQUEST FOR ADDITIONAL.INFORMATION k ~b ) A Figure 440.435-2 Supply Tank Mass (Reference 440.435 2) 440.436 4 YN

NRC REQUEST FOR ADDmONAL INFORMATION N. 1 8. 5. ~ 2 2k 5-RAL WBler-m e S-nat geltff= Stu RALWBIAN NA=67JIt b I s I a 3 a 3 s 3 5 8 2 4 6 8 e e a 1 4 bites Figure 440.435-3 Valve opening Ana As a Function of the Stem Travel for VLI 1 (Reference 440.435 2) 440.435-5

1 NRC REQUEST FOR ADomONAL INFORMATION - (4 A) Figure 440.435-4 Coesparison of the Quality Calculated by NOTRUMP and the Data Upstream of VLI 2 (A & M) Valve (Test 240). The thne for the data curve has been sidfted to the left for 3.5 seconds so that the thne zero is the actual opening tkne of the valve VLI 1. 44o.43s-4 g,

NRC REQUEST FOR ADDmONAL INFORMATION - @ A) ~ Figure 440.435 5 The Original Unshifted Plot of F1gure 440.4354. (Figure 4-27 of Reference 440.4351) 440.435-7

NRC REQUEST FOR ADDmONAL INFORMATION mm - 6mA] i Figure 440A354 C-: .--h of the Quality Calculated by NOTRUMP and the Data Upstream of the ADS Valva (FT6W)(Test 240). The thee for the data curve has been shifted to the left for 3J seconds so that the time zero is the actual opening thne of the valve VLI 1. 440.436-4 YO

NRC REQUEST FOR ADDITIONAL INFORMATION M ~ (A,& ~ l Figure 440.435-7 The Original Unsinned Plot of Figure 440.435 6. (Figure 4-28 of Reference 440.4351) 440.436-9

NRC REQUEST FOR ADDmONAL INFORMATION -%Q Figure 440.435-8 Comiparlson of the Quauty Calculated by NOTRUMP and the Data Downstream of the ADS Valves (Fr16WXTest 240). The thne for the data curve has been shifted to the left for 3J seconds so that the thne zero is the actual opening thne of the valve VLI 1. 440.436-10

NRC REQUEST FOR ADDmONAL INFORMATION '(Gt,b) L. Figure 440.435 9 The OW Unshifted N d % 440.435 8. > 4 3 d Refeitoce 440.4351) 440.436-11 y yg

. ~ _ _ _ _. _.. _. _ _ _. _ _. -__...._~... _.._ _.._. _.__ _..______ _ _....._.._.. I NRC REQUEST FOR ADDmONAL INFORMATION ~ ~ kp) Figure 440.435-19 Comeparison of the Quality Calculated by NOTRUMP and the Data at the Sparter Body (Test 240). De thne for the data curve has been shifted to the left for 3.5 seconds so that the thne zero is the actual opening thne of the valve VLI 1. 440.436-12 EN

NRC REQUEST FOR ADDmONAL INFORMATMN !ER - a,e i Figure 440.43511 De Original Unsidfted Plot of F1gure 440A35-10. (Figure 4 30 of Refersace 440.4351) no.4ss-is y

NRC REQUEST FOR ADDmONAL INFORMATION ~ M,5) Figure 440.435-12 C-: ;1'em of the Quauty c.icni u.i by NOTRUMP and the Data at the Sparger Arms (Test 240). De thee for the data curve has been shifted to the left for 3J seconds so that the thne zero is the actual opening thne of the valve VLI 1. 440.435-14 EO

i 4 1 1 1 NRC REQUEST FOR ADDmONAL INFORMATION n.- 1 l -@h) i i 4 i i j i 1 a l a i 1 J i Figure 440.435-13 The Original Unshifted Plot of Mgure 440.435-12. (Figure 4-31 of Reference 440.435-1) 440.435-15

l NRC REQUEST FOR ADDITIONAL INFORMATION Question 440.437 1 Re: NOTRUMP ADS PVR (RCS-GSR-003) NOTRUMP overpredicts the depressurization rate in the pressurizer for several tests while the fluid qualities in the ADS lines for these tests were underpredicted. Since lower quality should lead to a reduced depressurization rate, please explain this inconsistency. See for example Figs. 4-13, and 4-33,4-53. Also, these tests are only displayed for 30 seconds and only capture the very initial short period of the depressurization. Please explain why the comparisons were not carried out beyond 30 seconds or until atmospheric pressures are approached. Some of the tests show a marked deviation between the data and the NOTRUMP prediction suggesting the long term depressurization may be grossly overpredicted as in Figs. 4-53, while the flows show a growing discrepancy with the data as in Figs. 4-32 and 4-12 at 30 seconds. Since the ultimate judge of the ADS is its ability to depressurize the system to very low pressure, displaying the test comparisons for only the first 30 seconds where the system remains at elevated pressures does not demonstrate the NOTRUMP code ability to predact ADS depressurization over the full range of system pressures. Please provide the NOIRUMP comparisons to the data until the system has completely depressurized.

Response

The depressurization of the pressurizer (steam / water supply tank) depends only the flow rate as analyzed and verified with the data below. 'the higher the flow rate, the higher the 4 gizanon rate. NOTRUMP overpredicts the flow, therefore, it overpredicts the depressurization rate no maner the fluid qualities are underpredacted. There is no inconsistency. To show that the depressurization of the pressurtzer depends only on the flow rate but not on the fluid quality, j consider the control volume enclosing the pressurizer volume as shown in Figure 440.437-1. The conservations of mass, energy, and pressurizer volume are: (#,,, + #,,) - ( N,,, + M,,,) = AM,r = de (440.437-1) f (M,o's.o

Mr.o't.o) - (M.c*r,e
Mr.c r,,)

e a r t = f,;,,out (#, r.r.)de (#,, + N,,,) (440.437-2) =AN f uo.m-1

t I

i NRC REQUEST FOR ADDITIONAL INFORMATION 6 i I (M :V. c

Mr, e t. c) sr " ( M, o a. o + Mr. o f, o )

(440.437-3) V V V V r a a where: M = masses, Ibm, 3 a specific volume, ft /lbm, y J e = internal energy, Bru/lbm, H = enthalpy, Btu /lbm, l V = volume, ft', I { = mass flow rate, Ibm /sec, K.E. = kinetic energy Btu /lbm. Subscripts: g = vapor, f = liquid, 0 = time zero, t = time t, ST = pressurizer (steam / water supply tank). In equation 440.437 2, the K.E. is neglected. Suppose that the initial mass and pressure in the pressurizer at time j zero is given. Assume that the fluid is at saturation conditions initially and also later while flashing. That is, all the quantities with subscript 0 in the above three equanons are known and the quantities with subscript t are unknown. Although there are many quantities with subscript t, in fact there are only three unknowns: M, %, and y P,. The pressure P, is not explicitly in the three equations, however, all internal energies and enthalpics depend on P,. That is, once P, is found, the internal energus and enthalpies can be found from the steam table. Therefore, the three equations (1), (2), and (3) can be solved for the three unknowns M, Me, and P, if the flow rate ; is y i known. That is, the pressure P depends only on the flow raes ; and is independent of the fluid quality l downstream. This can be verified by two methods: (a) substitunng the time zero values and flow rate (or AMrr) from test data in the above thsee equenons, and solve the three equenons for masses and pressure at time t, which involves iteration since the pressure does not explicitly appear in the equanons, and showing that the calculated j pressure at time t agrees with data; or ahernatively. (b) substituung the time aero values and flow rate (or AMar)in the above three arp==== and showing that the test data at time t satisfy the three equanons, in the following calculations, the second teethod is used, since it is more straight forward and does not involve iteration. f 4 I M0.437-2

NRC REQUEST FOR ADDmONAL INFORMATION ADS Test 240 is arbitraily chosen for verification of the above argument. The time zero values can be obtained from Table B.1-2 (p.B-9) of reference 440.437-1 as follows: v,, = 0.02233 ft'/lbm 3 P = 1202 psia. p = 0.3617 ft /lbm, -+ v e, = 567.1 Btu /lbm ep = 1104.2 Bru/lbm. r 2 H,, = 572.1 Bru/lbm, p,, = 44.79 lbm/ft Vn = 1412 ft' Mg = 1818 lbm (M,3), = 26,476 lbm (see Figure 440.437-1) AMn = 12055 lbm What is needed in Equations 440.4371,440.437 2 and 440.437 3 is M,, but not (M,3),. 7he M,, can be calculated as follows: (Note, Vn = 1412 ft'. but we do not know V.. We only know that V. is approumately a h*=iaW volume of (4x/3)(6.98/2)' = 178 ft.) 8 3 Vg=Mvg g = 1818 (.3617) = 658 ft V,, = Vn - Vp = 1412 - 658 = 754 ft 3 Me, = V,, p,, = 754 (44.79) = 33,772 lbm 8 V. = [ M,, - (M,3), ) / p,, = (33.772 - 26,476) / 44.79 = 163 ft Substituting these time zero values in equanons (1), (2), and (3) with the neglect of the kinetac energy yields My + Mu =(Mg + Me,)- AMn = (1818 + 33,772)- 12055 = 23,535 lbm (440.437-4) Mep+Muu = (M eg + M,,e,) - AMn = [l818 (l104.2) + 33,772 (567.1)] e g r y -12055 (%) (572.1 + 556.7) = 14.4 x 10' Bau (440.437-5) M v, + Mu u v = Vn = 1412 lben (440.437-6) y 440.437 3

.w... -~ - . ~. .-.a- ~ -. -. - J NRC REQUEST FOR ADDITIONAL INFORMATION Since the data of M. M,.,, AMrt, and P, at the end of test (35 seconds) are given in Table B.12 (page B-9) of p reference 440.4371, these data are used for time t (35 seconds) values. These data are t = 35 sec. v,, = 0.02193 ft'/lbm 2 P, = 1094 psia p = 0.4031 ft /lbm, v e, = 552.3 Bru/lbm ey = 1107.7 Btu /lbm. r H,, = 556.7 Btu /lbm Substitute these data for time t values in equations (4) and (5), giving My + M,, = 23,535 (440.437-7) I107.7 My + 552.3 %, = 14.4 x 10' (440.437-8) Equations (7) and (8) can be solved for M and %,: y My = 2.444 (440.437-9) %, = 21.091 (440.437 10) Substituting equanons (9) and (10) in the left-hand side of equanon (6) gives 8 M v y + %, v,, = 2,444 (0.4031) + 21,091 (0.02193) = 1448 ft y 8 which is almost identical to the value on the right-hand side of equence (6),1412 ft, with the error of only 2.5 percent. Thus, it is seen that the pressunser pressure depends only on the total mass out of the pressunzer, AMrr, and the depressurtzanon rase depends only on the flow rase, ; The larger the flow rase, ; , the larger the depressurtzenos rase. Since NOTRUMP overprehets the flow rase, it also overpredicts the depressunzation rate, which is correct no maner what Gow quality downstream is prahcsed. In the six tests analysed, the VU-2 valve was closed at around 30 seconds because of the capacity of the steam / water supply tank (pressertmar) of the east facility. Therefore, the dass aher 30 seconds are -----it and all figures in the report are displayed for 30 seconds. The NOIRUMP compensons aher 30 seconds are not valid since the test valve closure was not modeled with NOIRUMP. 440.437-4 EN

NRC REQdEST FOR ADDmONAL INFORMATION j Reference 440.437-1 WCAP-14324 " Final Data Report For ADS Phase Bl Tests " April 1995. SSAR Revision: NONE l i l M0.437-5

a .m --.A e-A ,s0-- -w ---s-~*n---m J a a x---'n Aa---u-Lm a<&- M

A--*--a-

AAL

-- a --- a m --A

l NRC REQUEST FOR ADDITIONAL INFORMATION I

i b [ / \\ / \\ I l M,o 3 l l 1 I l I _. -.=_ - I n a pc s,., Vo/gm e l l I (M,*k.,I f 1 M,o l p I I I i-.........._J (M,.) \\ V> / M-r s / B 't ( N../ 1P QiLf Figure 448.4371 Seessa/Weser Sepply tank (Pnssartmed M0.437-4 gg

I l NRC REQUEST FOR ADDmONAL INFORMATION Ouestion 440.465 Re: NOTRUMP PVR FOR OSU TESTS, LTCT-GSR-001, JULY 1995 Fig. 2-2 shows the wall heat noding. Wall heat effects can represent a major source of heat for small break LOCAs which can subsequently affect depressurization, especially for the slow depressurization transients characterizing AP600 small break LOCA response. Please justify the omission of wall heat transfer from all of the external loop piping and the secondary system components.

Response

Although the depressurization in the OSU facility small break LOCAs is slow, it is much more rapid than a standard PWR due to the ADS valves. In the OSU noding, the intent was to remain as faithful to the standard plant noding as possible, whenever it was reasonable to do so. In the OSU facility, the total metal mass of all hot and cold legs is only 340 lb. This accounts for only about 3% of the metal mass in the RCS, "the more rapid AP600 l depressurization, which is controlled by the ADS and not the break, places less importance on the metal heat contributions of the loop piping than in a standard PWR. The level of detail in the metal heat nodalization for standard PWRs was therefore deemed adequate for modelling the OSU facility. SSAR Revision: NONE l i uo.m T wasnnshause

1 i NRC REQOEST FOR ADDITIONAL INFORMATION Question 440.469 Re: NOTRUMP PVR FOR OSU TESTS, LTCT-GSR-001, JULY 1995 In expressing the momentum equations from a mass flow to a volumetric flow basis, linearizations of the equations are performed. Provide the volumetric flow based momentum equations and the linearizations that were performed to change the equations to a volumetric flow base. Provide the validations that were performed to verify that the changes were made correctly. Also, provide the code benchmark for this model change.

Response

Following is the requested description. This description is in the form of a revision to Section 4.4 which will be included in the NOTRUMP Final V&V Report. Work is currently underway to respond to the request for validations and benchmark analyses. The schedule and scope of this work will be provided on or before 12/31/95. 4.4 Net Volumetric How Based Momentosa Egendom An option has been added to NOTRUMP to cast the momentum equation and drift flux equations for a given flow link in terms of net volumetnc flow rate rather than net mass flow rate. The advantage of this modtficanon is two. fold. First. having volumetric flow rate as the iwtarwad*at variable in a flow link allows the mass flow rate to change instantaneously as densities in the two adjacent nodes change. This improves the behavior of the node stacking and mixture-level tracking model, as well as the behavior of other flow links that experience large density gradients in time and space. It yields significant reductions in pressure oscillations, particulady at low pressures where the density differences between liquid and gas are the greatest. Second, drift flux models, in general, work better when cast in terms of net volumeanc flow rate, since drift flux is a volumenic flow concept. The mass and energy equations are not directly impacted, since the drift flux model still gives, as its outputs, the phasic mass flow rates. Only the haeanzanons of these equations, with respect to the volumetnc flow rate are changed and they are j generally simpler than the current linearizanons with respect to mass flow rates. i The mass flow-based momentum equanon used in N(y! RUMP is given by aquation (2 33) of Reference 1. It is also { written in a more general form as equanon (2 38). Bodi of these equations are differential equanons written in terms of the temporal derivative of the mass flow rase W. It is also possible to write these equations in terms of the temporal derivative of the volumeene flow rate Q. To do this refer to the drift flux equanons in Appendix G of Reference 1. The equanons for the phasic volumetnc fluxes <j,> and <j,> in terms of the net (or total) mass flux G are P (1-$cc>C.) G- <<V >> o <j,> = (G 24) and ( <cc>C,1 G Q < <v,> > 8 < j,> = (G-25) 1 P., 440.469-1 3N

---.. -.-. -.. - -... - _ - ~ - _ _,... _. - _ _. _ _. - - - _ _ _. - - _ _ _ _ _ i NRC REQUEST FOR ADDITIONAL INFORMATION i EM-where 1"*C """C p; = a a (G-26) + Adding equations (G-24) and (G-25) gives the following equation for the net volumetric flux <j> in terms of the net mass flux G. G+ c a> < <V,3 > > <j>= (4.4-1) P., Multiplying by the flow area A gives the following equanon for the net volumeeric flow rase Q in terms of the net mass flow rate W. W+ c ot> < < V,3 > > A Q= (4.4-2) P., Differentiating equanon (4.4-2) with respect to tinw t and neglecting the temporal derivatives of p; and the second term in the numerator gives l Q=d (4.4-3) 9. It is this relanonship that is used to change equanoes (2 33) and 2 38) froen differential equanons for W to differential equanons for Q. Since the state variable for volussetnc flow based manwatues aquences is now Q resher than W. the linearizanons in thr central numencs must be with respect to Q for any flow link with a volumeenc flow-based momentum equanon. The decads are now prosessed. In Appeedix E (nm.M Numancal Equences and Solution Technique) of Reference 1, all occurrences of AW's and subsenpt W's are replaced by AQ's and subsenpt Q's, respectively, for those flow links that use a volumeeric flow-based -m= equenom rather than a mass flow-based momentum equanos la other wonis, the seses variable for these links is Q and thus the lineenaanoes are with respect to Q for these links. Two posses shoald be acted about the equenons of Appendut E: (1) the quencess Q" and Q refer to V heat roses. not volumeene flow rates, but there should be ao confusion with the vohaneanc flowrees Q since the beat rates always appear as r, M,: f vanables;(2) only mosH:nocal flow links (k=1,.. K) have momeonam equenons (volumetnc or mass based) so the critical flow links (k=K+1..... K*) are is no way impacted. There are two casesones of changes in these equenoas. Fust, from equence (4.4 3), it is seen that the volumsene flow-based M0.469-2 Y

d NRC REQUEST FOR ADDITIONAL INFORMATION momentum equation is obtained from the mass flow rate-based momentum equation by dividing by p;. In Appendix E of Reference 1, the vector and matrix form of the mass-flow based momentum equation is given by Bw, Aww, A.,, A.,, A,,, and A.,. Thus the matrix coefficients B, Ax, Ag, Ag, g A and Ag, are obtained by a i dividing B,,, A., A.,, Ag, A,, and Ag, respectively, by p;. This potentially impacts equations (E-5), (E-53) - (E-56), (E-60) - (E-64), and (E-148) - (E-150). Second, linearizations fer flow links with volumetric flow-based j momentum equations must be with respect to the state variable Q. This includes A, Ay, Ay, Ay, v. and A The potentially impacted equations are (E-5), (E-12), (E-19), (E 26), (E 33), (E-35) - (E-38), (E-40), (E-43), (E-46), i (E-49), (E-53), (E-54). (E-57), (E-60), (E-65), (E-71), (E-76), (E-82), and (E-148) - (E 151). A involves the nn linearization of the volumetric flow based momentum equation with respect to Q and will be covered shortly. First, however, the linearization of the mass and energy equations will be discussed, i.e., the calculation of and A Ay, Ay, Ay, g. 1 The derivatives (Wh)fm. Wf.. (Wh)!.., and W7,a are replaced by (Wh) f.m. Wf.x, (Wh)I,m, and Q7,=, respectively, for those non-critical links k (k = 1,.... K) that have a volumetric flow-based momentum equation. Since (Wh)I. Wf,. (Wh)I,=, and W7,a are given by equations (2 (2-8) of Reference 1, (Wh)I. = Cl,n - (h ) i,, + Cf. - ( h,) i,,, (4.4-4)

W: ..=cf... y.c!... y.

,. 4-,) (Wh)I = (1-Cl,,) - ( h,,) i,, + (4.4-6) 3(W ) (1-Cf..) - ( h,),,, and 440.469-3

a NRC REQUEST FOR ADDITIONAL INFORMATION ) 'Ah 0"' k B Wr) (4.4-7) W. [ 1 -C,8, ) W + [ 1 -C,'.. ] - OW. 1 The analogous derivatives with respect to Q are 0 3 (W,) 3 ( W* ) " - g ( Wh ) f, = = C.',, - ( h,),,, + C ', n - ( h,,),,,, (4.4-8) e i W" = C '. = - ( "' I " + C '. m - y'I" a (4.4-9) g 4.= t t (Wh)I, = (1 -C ',,) (h l,, + oi (4.4-10) [ 1 -C ',,) ( h,) i,,, i and 3W '. = 3(W l h W.In (4.4-11) g, g g.c a.j y. g i _c.e.j. y 6 e It can be seem that the only ddleremos between equenons (4.4-4) (4.4-7) and (4.4-8) - (4.4-11) are that & (W,),/ &W, and &(W,),/DW, are replaced by &(W,),/SQ, and &(W ),/SQ,, respectively. 'Ibese are the derivatives of the phasic mass flow ruess with respect to the not flow rese (inans or volumeene). They are calculased as e 1 3 (<de>)n O(W)., W (4.4-12) W N m 440.469-4 YO

NRC REQUEST FOR ADDmONAL INFORMATION i 8(w,), 1 8 ( < j,> ), (4.4,13) dW ( U,) m dG m m 3 (W,) = 1 3 ( <d e> ) = (4,4_ g y T, (V )g d <] >m e and 3 (W,) 1 3 ( < j,> ). (4.4-15) T V O (J >= The derivatives of <jp and <jp with respect to G are derived from equanons (G-24) and (G-25) of Reference I and are given in Appendix G as < <V > > + < d > g (1-< p C.) n (G-38) y T p; and <cc> C, - < <V > > + < j > e go.393 3,3,, T PE The derivatives of <jp and <jp with respect to j are derived from equenon (G-16) and (G-17) of Reference 1 and are 440.469 5

NRC REQUEST FOR ADDITIONAL INFORMATION O <ds" .M,3 > >.,3, c& C.. , ( 1_,cx, e,).,cx, (4.4-16) o<3> c<3> <3>, and 0"de> '8 C, (4,4_173 = < CE> C* + < ct> +<j>d<3>, 0] a<3> The drift flux routines already return the derivatives of <<V,>> and C, with respect to both G and < j > so all the information necessary to calculate %, Q, %, and % is available. A involves the linearization of the volumetric flow-based momentum equation with respect to the state vanable gg Q and will be discussed now. Consider now the frictic,nal pressure drop term in equanon (2-33) of Reference 1. It is - C,l W,l W, where W is the state variable for mass flow-based mo==anim equenons and where C (callitCl for clarity) is the friction coefficient calculated as described in Secnoa 5 of Reference 1. For volumetric flow-based momentum equanons one can define the fricconal pressure drop tam as - Cf l Q,l Q, where Q is the state variable and where Cf is related to C," by Cf = ( u") ' - g is the specific volume in flow link k. For the new voluneetne flow-based momentum equation option in NOTRUMP, there are actually two fricuon opoons avadable. For an input of ITYPEFL = 11, the frictional term is based on the state vanable Q and on Cf. For an input of ITYPEFL = 21, the form of the frictional term is the original mass flow-based form using W, and Cf. Here it is important to remnsunhar that W is no longer the state g vanable so that la the haeanzation this incnomal term must be hacensed with respect to Q. In equance (E-40) of Referstaos I for A,, the quantity of &F,/ BW, (i.e., u = k) includes the fricdonal term which is I

8Ff' 144 g*

I 2 Cf - l W,l = %n.u

== l 1 EO I e

NRC REQUEST FOR ADDITIONAL INFORMATION For Agn, the quantity of S F,/ SQ, includes the frictional term which for ITYPEFL = 11 is (2.L/ Af, - .- l Q,1 (. -20) and for ITYPEFL = 21 is i "l ( ,,,,,, " ( J.L / A, ~ and where S w, & (w,), M, T, 3(w,)* M.b22) 09 3 (W,),/ 8Q, and 8 (w,),/ 8Q, are given by equanons (4.4-14) and (4.4-15), respectively. The decision to cast the NOTRUMP momentum equation and the drift flux equations in terms of net volumetric flow rate rather than mass flow rane is based on the following. Most state-of-the-art codes such as TRAC and RELAP5 use velocity-based momentum equations. It is generally MM that driA flux is more easily applied and more successful in a volumetnc flow context because drift flux is basically a volumeenc-flow or velocity concept. 440.469-7

NRC REQUEST FOR ADDITIONAL INFORMATION ilR Note: The final NOTRUMP V&V report will contain a list of variable nomenclature. The following nomenclature will be included in the list. 2 flow area (ft ) A = drift flux distribution parameter C, = total mass flux (Ibm / sec / ft') G = specific enthalpy (Btu / lbm) h = volumetric flux (ft' / sec / ft ) 2 j = volumetric flow rate (ft' / sec) Q = time rate of change of Q (ft' / sec ) 2 3 = drift velocity of vapor relative to the total volumetric flux (ft / sec) V, = W = net mass flow rate (Ibm / sec) time rate of change of W (lbm / sec') 47 = X quality ( - ) = density (Ibm / ft') p = specific volume (ft' / lbm) U = void fraction a = Subscripts: f liquid phase = vapor (gas) phase g = Reference 44049-1 P. E. Meyer, et. al., "NO1 RUMP - A Nodal Transient Small Break and General Network Code," WCAP 11079-P-A (Pi+Ms.y), WCAP-10000-A (Non-propnetary), August 1985. SSAR Revision: NONE 440.469-8 E w

l NRC REQUEST FOR ADDITIONAL INFORMATION Ouestion 440.472 Re: NOTRUMP PVR FOR OSU TESTS, LTCT-GSR-001, JULY 1995 In Section 4.7, liquid reflux flow links were added to prevent the nonphysical depressurization of nodes with no mixture regions when subcooled liquid enters. Adding subcooled liquid from the hot legs to a lower core node, for example, could result in artificially cooling the fuel. Please demonstrate that artificially adding the subcooled liquid to the mixture region below the upper steam regions in the core does not artificially cool the fuel. Also, how does this methodology affect level swell, bubble rise, and steam production in the mixture region to which the subcooled liquid is added? Please explain in detail.

Response

As stated in Section 4.7 of LTCT-GSR-001 and PXS-GSR-002, the new internally calculated liquid reflux flow links are a generalization of the NOTRUMP model for hot leg to reactor vessel reflux which is described in Sections 3-1 10 through 3-1-12 of Reference 440.4721. This model which was appioved in the NOTRUMP SER is still used i i for the reactor vessel. For AP600 applications, the new generahzed model is used for the steam generators prunary sides, for the CMT's, and for the multi-node downcomer of the SPES-2 facility. Even though the model for hot leg to reactor vessel reflux has not been changed, its impact will be discussed. The RAI asks for an explananon of why adding the subcooled liquid to the mixtme region below the upper steam regions in the core does not artificially cool the fuel. " Ibis request assumes that the core is uncovered since it refers to " steam regions in the core." "Ihe core does not actually uncover for AP600 during small break LOCAs. If the core were to uncover however, then the steam above the core mixture level would be sy de; d and at least some of the core region below the mixture level would likely contain a two-phase saturated mixture. In this situation, most of the liquid entering at the top of active core region would be expected to fall to the mixture level while slightly de-superheating the steam above the mixture level and reducing the quality of the two phase mixture just below the mixture level. The NOTRUMP model for hot leg to reactor vessel reflux would, in this situation, put the reflux liquid into the mixture region just below the mixture level (i.e., into the mixture region of the stacked mode containieg the single stack mixture elevation). This mixture region would most likely be two-phase. In this case, the reflux liquid, whether saturated or stW. would reduce the quality of the mixture region but not alter its temperanue In the unlarly case that the mixture region were subcooled, then the reflux liquid would alter the temperature of the region in a manner depending on the temperature of the reflux liquid to the temperature of the subcooled region. (The temperature could increase or decrease.) For this unkkely case, however, the fuel would be well cooled anyway, so that this altering of the mixture region tempersent would have little impact. The NOTRUMP model does not account for the slight de-superkmang of the superheated vapor above the core mixture level as the refha is directed to the mixture level. This is conservative during core uncovery he=e (1) by keeping the =-----i ^-1 vapor hoenr. it keeps the exposed fuel (i.e., the fuel above the mixture level) hotter; and (2) by not de-superheannag (or eves naturanas and condeastag) the vapor, it keeps the level depressed. If this is contrasted to the conconservative and physically less reahsuc case of no reflux links, the reflux liquid would desuperheat and possibly condense all the vapor as the reflux hquid matantly comes to thermal equilibrium with the steam above the core. This would not only unr=alianeally depressurias the regions above the core mixture level but also nonconservatively cool any exposed fuel and cause the mixture level to rise. 440.472 4

.~ 1 NRC REQUEST FOR ADDITIONAL INFORMATION I l 1 1 In the NOTRUMP SER, the NRC found the NOTRUMP core model, of which the hot leg to reactor vessel reflux j model is an integral pan, to be acceptable. Based on this assessment. it was felt to be unnecessary to change the i model for hot leg to reactor vessel reflux for AP600 calculations. It was decided, however, to generalize the model for use in other components of the AP600 (e.g., steam gene ator tubes. CMT's, and multi-node downcomers). It is the generalization that is described in Section 4.7 of LTCT-GSR-001 and PXS-GSR-002. Reference 440.472-1 N. Lee, et. al.. " Westinghouse Small Break ECCS Evaluation Model Using the NOTRUMP Code," WCAP-10054-P-A (Proprietary), WCAP-10081 A (Nonproprietary), August 1985 SSAR Revision: NONE 440.472-2 T

NRC REQUEST FOR ADDITIONAL INFORMATION Question 440.484 Re: NOTRUMP PVR FOR OSU TESTS, LTCT-GSR-001, JULY 1995 Please provide a clad temperature calculation to show the effect of the changes to the transition boiling correlation calculation on peak clad temperature for a heatup transient that experiences transition boiling heat transfer.

Response

Section 4.19 of LTCT-GSR-001 and PXS-GSR-002 describes the changes implemented to the numerical solution technique employed in NOTRUMP heat links when the Westinghouse Transition Boiling Correlation is used. The details of the calculations for NOTRUMP heat links are given in Section 6 of Reference 440.484-1. It must be pointed out that NOTRUMP heat links are not used to model core heat transfer. The core fuel rod model and its associated heat transfer conelations, described in Appendix T of Reference 440.484-1, are used to model core heat transfer. No changes have been made to this model for AP600 applications As such, the request for a clad temperature calculation to show the effect of the changes described in Section 4.19 on peak clad tea 44.uus is not applicable. Also, since the core does not uncover, it does not experience transition boiling. Reference 440.484-1 P. E. Meyer, et. al. "NOTRUMP - A Nodal Transient Small Break and General Network Code," WCAP-10079-P A (Propnetary), WCAP 10080-A (Ncs.y.vy.;ctary). August 1985 SSAR Revision: NONE M0.484-1

=-. l NRC REQUEST FOR ADDmONAL INFORMATION \\ l Question 440.505 l Re: NOTRUMP PVR FOR OSU TESTS, LTCT-GSR-001, JULY 1995 Please explain the source of the oscillations in break flow from about 150 to 240 seconds and 340 to 430 seconds in Fig. 5.4-24. Please explain why the NOTRUMP code does not simulate the data nor trends and underpredicts the break flow from 120 seconds until the end of the transient at 500 seconds.

Response

In the NOTRUMP simulations, the oscillations seen between 150 and 210 seconds are due to water from Accumulator 1 injection periodically recovering the break link, leading to ahernating vapor and liquid flow out of the break. Similarly, the oscillations between 340 and 430 seconds are due to IRWST injection into the broken DVI line periodically recovering the break. This effect is a direct result of the discrenzanon implicit in NOTRUMP. Such effects are typical of what has been seen qualitatively in other computer simulanons when modeling the break and the cold leg refilling behavior. As was stated in the OSU preliminary vahdanon report Snal test data was not available when these comparisons were made. When one calculmaan the break flow rate in the test by adding the CMT flow (determined from the rate of change of the mass in the C.!T) to the accumulator flow, and comparse it to the same quantities in the NO1 RUMP calculation as shown in Figures 440.505-1, the agreement is much bemer. Note that this comparison has been adjusted to eliminase the flow component from the IRWST injection line in the NOTRUMP simulation to maintain consistency with the quantity plotsed in the new test data curve. At approumately 130 seconds, both the test data and the NOTRUMP simulation predict a shon period of predominantly vapor flow until Accumulatae I resumes flow. During the following accumulator injection penod, the flows again are similar, except for the oscillanons explained above. SSAR Revision: NONE M0.506-1

NRC REQUEST FOR ADDmONAL INFORMATION (a,b) Maure 440.5051 CMT and A--* Mass Mow Race for OSU Test SB12 44o. sos-2 gy

i l k NRC REQUEST FOR ADDITIONAL INFORMATION Question 480.214 Re: Questions on OSU/ APEX Sump Behavior: Review of the tests in the OSU/ APEX facility has resulted in uncertainty about (1) the modeling of the containment sump in the facility, and (2) how the " primary" sump communicates with both the " secondary" sump and the reactor . cooling system. In the Test Specification for APEX, Section 6.0, p.16, it is stated, "A vessel shall be provided to simulate the i flooded volumes in the lower containment. This vessel shall be sized to contain all water from the reactor coolant system (RCS), ACCS, CMTs, and in-containment refueling water storage tank (IRWST)." There is no differentiation in this statement between the pnmary and secondary sumps, nor 1:ow the volume of the two sump tanks is apportioned to represent the AP600 sump. However in the APEX scaling report, Secnon 7.3, p. 7-11, it is stated, "The containment sump will accommodate all of the IRWST, CMT, and accumulator liquid volumes." (Note that the RCS does not appear.) The APEX scaling report goes on to relate the pnmary sump tank and the secondary sump tank to lower containment volumes available for recirculanon to the RCS (referred to as the sump) and those that are not available for recirculation (referred to as "normally non-flooded"), respectively. The " curb" or "spillover" elevation is denoted as that point at which fluid filling the non-flooded volumes would spill over into the sump. Part of the quescon about sump tank volumes relases to the totalliquid volumes and accammadaria= thereof in the sump. It is also stated in the scaling report that the reladve elevances, volumes, and the "spillover" elevation of the pnmary and secondary sumps are properly scaled in APEX. a. The total volume of the contamment sump, up to the " curb" elevation, is gives in the APEX Scahng Report as $8,263 ft3. However, the total liquid volume in the CMTs, accumulators, and IRWST is: 2000 ft3 per CMT; 1700 ft3 per accumulasor; and, as given in Sectice 6.5.3.1, p. 6-93 of the Scahng Report, the IRWST volume is 70.798 ft3. The total of thsee volumes is thus 78.198 ft3. Reconcile the =nammach between the total volume and the sump volume, in light of the quoted statement ce p. 7-11 regarding the capability of the sump to accommodase these volumes. Nose: Also address the staammeet in the APEX Test Specificanon regarding accommodanon of these volenes plus that of the RCS, given that the RCS volume adds another 7280 ft3 to the total volume. (Volume of RCS taken from AP600 standard safety analysis report (SSAR). Table 5.1-2.) b. How much liquid volane must exist in the sump to flood to an elevanos adequess to permit recirculation from the sump to the RCS7 The ~'nonnally non-flooded" an=e===ame volane is gives os p. 711 of the scahag report as 35,403 ft3. c. Demoeseems that, if a break were to occur such that these comperaments were the first to flood, enough water would flow over the " curb" isso abs sump to flood the senp to a level permining recirculanory cooling.

Response

The pnmary and secondary swaps at the O$lJ test facility were scaled to represset the sonnally flooded and a. unflooded cone=====e comparansats respectively. The total " sump" volans, both prunary and secondary, is equivalent to the sun of all the comparaneees and is sufBesset to aaa-ade the volanes of the IRWST, CMTs, accumulators, and RCS. 440.214-1

NRC REQUEST FOR ADDITIONAL INFORMATION b. The plant design has the direc* vessel injection centerline at the 99' 7" elevation. In order to permit recirculation, the sump (containment compartments) must flood to this elevation, plus the RCS pressure. The design floodup elevation (including flooding of one of the normally non-flooded compartments) is 107 feet. c. For the AP600 design, as presented in the OSU scaling report, should a loss of coolant occur in one of the "normally non-flooded" compartments of containment, this compartment would be the first to fill. 7he water would then overflow into the normally flooded areas. Using the numbers provided in Table 8-9 of the scaling report, the normally non-flooded volume (two non-flooded compartments) was 35,403 ft' and the sump volume below the DVI was 37,063 ft'. Using 85,478 ft' as the volume for the IRWST, CMTs, accumulators, and RCS, and subtracting the non-flooded containment volume and the sump volume below the DVI, the volume available for flooding above the DVI elevation was 13012 ft'. Table 8-9 provides a cross sectional area for the sump 2 above the DVI elevation as 2793 ft. This results in 4.7 feet of water elevation above the DVI line. Note however that the OSU secondary sump is representative of several normally non-flooded containment compartments. If such a break were to occur, only one of the normally non-flooded compartments would fill with water. Also, these compartments now have drain connections to the normally flooded area (OSU primary sump). The normally non-flooded compartment would rise concurrently with the normally flooded area. SSAR Revision: NONE 480.214-2

NRC REQUEST FOR ADDITIONAL INFORMATION Question 480.215 Re: Questions on OSU/ APEX Sump Behavior: As the IRWST drains and the sump fills, recirculatory cooling will eventually switch over from the IRWST to the sump. If there is no overlap between the water level in the sump and that in the IRWST when IRWST injection ceases, there may be a delay in sump injection, or a reduction in recirculation flow into the RCS. Show that for the scenario postulated in 1.c. above, ei her that (a) there is an adequate overlap between sump and IRWST levels to prevent cessation or reduction in RCS flow, or (b) that any such effects would be of sufficiently brief duration so as not to result in unacceptable co:e cooling conditions.

Response

The OSU secondary sump is representative of several normally non-flooded contamment companments. These compartments have drain connections to the normally flooded area (OSU primary sump). If a break were to occur in one of these compartments, this compartment, which is a portion of the non-flooded area, would fill with water concurrently with the normally flooded area. The floodup level with one normally non-flooded compartment and the normally flooded area together is 107 feet. The bottom of the IRWST is 103 ft., therefore, sufficient overlap exists to prevent cessation of RCS flow. SSAR Revision: NONE I 4ao.215-1

NRC REQUEST Fol'l ADDITIONAL INFORMATION -M Question 480.244 Re: Test OSU-F-01: The data on ADS lines is not usable, because the lines did not stay full as planned. Westinghouse should explain how these lines will be characterized for use of the information in analysis codes.

Response

During the course of testing, the field engineer opened RCS-620, located at the top of the separator, and came to the conclusion that, because there was no water issuing from the vent line, the lines leading to the separtor were not full. The Quick Look Report (LTCT-T2R-002) reported this conclusion. However, as the test data was analyzed more fully, there was evidence that the ADS separator inlet lines were completely filled with water and that pressure in the separator forced the water through the liquid drain line. A complete discussion of the test, including estimated line resistances and pressure drops is presented in Section 4.2.9.3 of Reference 480.244-1. Reference 480.244-1 WCAP 14252, "AP600 Low Pressure Integral System Test at Oregon State University: Final Data Report," Propnetary (LTCT-T2R-100), May 1995. SSAR Revision: NONE i l 4 4ao.2m-i

i 1 4 NRC REQUEST FOR ADDmONAL INFORMATION Question 480.245 Re: Test OSU.HS-01: The staff notes that the data for ambient heat losses at 100 F is unusable. Westinghouse indicates that the test is acceptable even though this part of the test was not completed. Westinghouse should justify the acceptability of the test in light of its failure to achieve one of its objectives.

Response

l The purpose of the HS-01 hot functional test was to obtain data under a variety of conditions to determine OSU facility characteristics. It was virtually impossible to maintain stable conditions at the low steam and feedwater rates necessary to maintain 100*F. However, usable data was obtamed for the facility at 200*F,300*F, and 400'F. This data provided an adequate characterization of the facility heat loss, therefore the test was acceptable. SSAR Revision: NONE l 4 I a f d 4 me.us-i

NRC REQUEST FOR ADDITIONAL INFORMATION =. Question 480.252 Re: Test OSU SBI: There appear to be some instruments that are not properly zeroed For instance, see Plots 26,27 and 28. for the accumulator level and pressure. These errors should be accounted for in Westinghouse's analysis.

Response

As noted in the Quick look Report for SBI, the Bourdon pressure tube indicator PI-401 (PI-402) was tubed to the lower portion of the reference leg for differential pressure transmitter LDP-401 (LDP-402). As pressure in the accumulator was increased, the air inside the Bourdon tube was compressed, thereby lowering the reference leg liquid level. This resulted in a false indication of measured level which was reported in Reference 480.252 1 and corrected, when used, in the analyses performed in Reference 480.252-2. Reference 480.252-1 WCAP-14252, "AP600 Iew Pressure Integral System Test at Oregon State University: Final Data Report," Proprietary [LTCT T2R 100), May 1995. 480.252-2 WCAP-14292, Revision I, "AP600 tow-Pressure Integral Systems Test at Oregon State University Test i Analysis Report," Propnetary [LTCl'-T2R-600), September 1995, i l SSAR Revision: NONE l \\ l l l 480.252-1

i NRC REQdEST FOR ADDITIONAL INFORMATION l Question 480.253 Re: Test OSU SBl: The description of events in the beginning of the report (p. 6-2) leaves out a great deal ofinformation. For example, the timing for various features described for instruments LDP-il5 and LDP-127 appears to be different from that seen on the plots; in addition, the description of the behavior of LDP-140 leaves out a number of dynamic features (e.g., the sharp = pikes at about 4000 and 5000 seconds that have been shown by the staff to be associated with CMT l refill). The staff expects that a much more thorough analysis of the dynamic systems interactions noted in this and other similar tests will be uadertaken in future reports on the APEX testing.

Response

The Quick look Report was used as a mechanism to provide data to reviewers in a timely manner. 'Iberefore, an evaluation of all test phenomena was not provided. The Quick look Reports have been superseded by References 480.253-1 and 480.253-2. For discussions of SB01, a 2-inch break in the bottom of the cold leg, see section 5.1.1 of Reference 480.253-1 and section 5.1 of Reference 480.253-2. Reference 480.253-1 WCAP-14252, "AP600 Low Pressure Integral System Test at Oregon State University: Final Data Report," Proprietary [LTCT-T2R-100), May 1995. 480.253-2 WCAP-14292, Revision 1, "AP600 kw Pressure Integral Systems Test at Oregon State University Test Analysis Report " Propnetary (LTCT-T2R-600), September 1995. SSAR Revision: NONE 480.253-1

l I NRC REQUEST FOR ADDmONAL INFORMATION Question 480.254 Re: Test OSU SBI: Negative gage pressures are shown for several instruments, including pressurizer pressure (Plot 18) and ADS 13 separator pressure (Plot 53). These need to be explained.

Response

As described in section 5.1.1 of Reference 480.254, the negative pressures seen on the pressurizer and ADS l 3 separator pressure were due to the lack of a vacuum breaker on the sparger line inside the IRWST. At approximately 2000 seconds, the pressurizer surge line began to refill. At approximately 3200 seconds, the pressurizer began to reflood. Also at this time, the sparger nozzles were still submerged. As the piping and components cooled between the pressurizer and the sparger, the steam condensed inside and the pressure fell, resulting in a slight vacuum in this line. A vacuum breaker was installed following this test. Reference 480.254-1 WCAP 14252, "AP600 law Pressure Integral System Test at Oregon State University: Final Data Report," Proprietary [LTCT-T2R-100), May 1995. SSAR Revision: NONE M.MI

l NRC REQdEST FOR ADDITIONAL INFORMATION i Question 480.255 i l Re: Test OSU SBl: What effect, if any, results from the top of the CMT being heated ta approximately 150*F prior to the beginning of the test?

Response

As indicated in section 5.1.1 of Reference 480.255-1, CMT-2 temperature indicated by TF-532 was 154.7'F. However, further data provided in Reference 480.255-1 indicates that less than 15 percent of the CMT volume was at a temperaure greater than 80*F. Although this elevated temperature will affect ClWT performance (slightly less mass in the CMT resulting in a slower recirculation rate), analysis of the test using the elevated initial temperature is still possible. l Reference ) 480.255-1 WCAP-14252, "AP600 Iew Pressure Integral System Test at Oregon State University: Final Data Report," Proprietary [LTCT-T2R 100], May 1995. i SSAR Revisson: NONE i i 480,256-1

l NRC REQUEST FOR ADDITIONAL INFORMATION j s 4 Question 480.256 Re: Test OSU SB3: The staff notes that the CMT temperature again was significantly elevated near the top. This is not specifically attributed to the PBL warmup prior to the test, but it is assumed that this is the explanatit'c. It would be valuable. ) however, to include such notes either in initial conditions list or, even better, in the Test Procedure section, rather than simply stating that the test was performed according to an established procedure. This type of information helps the staff differentiate true anomalous indications from those that are easily explainable by vinue of facility operauon procedures. j 1 d

Response

i As noted, the elevated CMT temperature was due to pressure balance line warmup prior to the test. Section 2.7 of 1 4 the Reference 480.256-1 provides a discussion of the pre-test operanons that were performed prior to each of the matrix tests. In addition, a discussion of the system configuranon and initial conditions is provided for each matnx j test discussed in Section 5 of Reference 480.2561. ] Reference I 480.256-1 WCAP-14252, "AP600 kw Pressure Integral System Test at Oregon State University: Final Data Report." Propnetary [LTCT-T2R-100), May 1995. 4 SSAR Revision: NONE i a l 4 4 M.N!

~.... NRC REQUEST FOR ADDITIONAL INFORMATION Ouestion 480.257 i Re: Test OSU SB3: The erratic response on the PRHR HX outlet flow (Plot 44) is somewhat puzzling to the staff, since it would be expected that this would be in single phase flow, unless these is ingress of non-condensible gas. Please explain.

Response

As is the case with many of the tests, during accumulator injection the PRHR flow decreased to near zero and the PRHR level decreased The PRHR HX inlet fluid temperature became subcooled and began to decrease This was an indication that there was no flow through the PRHR heat exchanger. The erratic response of the PRHR HX outlet flow may have been due to either the outlet line which was not completely full or to oscillations of the liquid in the loop seal between the bottom of the heat exchanger and the steam generator. SSAR Revision: NONE i 480.257 1

NRC REQUEST FOR ADDITIONAL INFORMATION Question 480.259 Re: Test OSU SB3: Explain why power is not listed as a specified initial condition. Also. at the end of the test, the power meters go negative. Is this an expected response, or does it raise questions about the accuracy of the power measurements during the test? Finally, the staff notes that the power is increased in a step fashion just before the test begins. Presumably this is a planned event; however, it is not described in the Test Procedure section nor in the list of initial conditions. This type of action needs to be flagged and explained. Response-The AP600 Low Pressure Integral Test at Oregon State University Final Data Report, May 1995, section 2.6.12 1 describes the control algorithm used to simulate the decay power expected in the AP600 plant scaled to the OSU Test Facility. For all matrix tests except SB21. the control algorithm was: For 0 < time s 140 seconds; power (KW 101 or KW-102) = 300 kW For time > 140 seconds; power (KW 101 or KW-102) = 300/[1 + B(t-140)f ] The Matrix Test SB21 decay power algorithm was: For 0 < time s 140 seconds; power (KW 101 or KW 102) = 300 kW For time > 140 seconds; power (KW-101 or KW 102) = 300/[1 + B(t 140)f where: B = 0.01021 and C = 0.2g48 Prior to time zero, the test facility was controlled to maintain the hot leg : +.are specified and not to a specific power level. At time zero, the power would change to 300 kW. Power is therefore not specified as an initial condition. At the end of the test, the indicated power is negative. This is an expected response on the DAS to opening of the reactor breakers it does not raise quesnons about the accuracy of the power measurements during the test. SSAR Revision: NONE i 480.259-1

NRC REQUEST FOR ADDITIONAL INFORMATION Question 480.260 Re: Test OSU SB3: The BAMS discharge line thermocouples (Plots 75,76) show considerably different behavior. TF-916 shows that the discharge is largely saturated during the long term portion of the test. However, TF-917 (signal conditioned output) shows significant subcooling in the exhaust flow. Explain this apparent discrepancy.

Response

Hot leg temperatures (plots 13,14.15.16) indicate that the hot legs are subcooled from about 3800 seconds to about 8000 seconds. This would indicate that no steam is leaving the vessel and exiting the BAMS during this time. Thermocouple TF-917 was on the line used for steam flow during this test. 'th-vawpic TF-916 was on a closed line. When steam flow dropped. TF-917 experienced a gradual cooldown. When steam flow began again at about 8000 seconds, the cooldown ended and the temperature again began to rise to saturation. Also, it should be noted that the two thermocouples ofin two different heat traced zones which are operated by independent controllers. The differences in temperatures are due to a combinanon of the heat tracing, the open vs. closed pipe, and the steam flow. SSAR Revision: NONE i 440.260-1 W wastinpouse

+ NRC REQUEST FOR ADDITIONAL INFORMATION = 115 Question 480.263 Re: Test OSU SB9: There appears to be a significant number of failed and/or erratic instrumentation in this test, and there is an admission that not all instruments met specified acceptance criteria. There is no " critical instrument" list provided, no specific indication as to whether any of the failed instruments would have been considered " critical," and no indication how missing critical instrumentation was compensated for. Since this is a " blind" test, with no data presented in the QLR for review, there is no way to confirm at this time that Westinghouse's judgement regarding the acceptability of this test is reasonable. The staff will review the data from this test when it is provided.

Response

The Quick Look Report was used as a mechanism to provide data to reviewers in a timely manner Therefore, an evaluation of all phenomena was not provided. The Quick Look Repons have been superseded by References 480.2631 and 480.263-2. The performance of any failed instruments on the critical instrument list is saw<=A for each test in Reference 480.263-1 as to the test acceptability. For discussions of SB09, a 2-inch break in the bottom of the cold leg, see section 5.3.2 of the Reference 480.263-1 and section 5.4 of Reference 480.263-2. Reference 480.263 1 WCAP 14252, "AP600 Low Pressure Integral System Test at Oregon State University: Final Data Report," Picpchy (LTCT-T2R-100), May 1995. 480.263 2 WCAP-14292, Revision 1. "AP600 Low Pressure Integral Systems Test at Oregon State University Test Analysis Report," Propnetary [LTCT-T2R-600), September 1995, SSAR Reymon. NONE 480.263-1

NRC REQUEST FOR ADDITIONAL INFORMATION Question 480.264 Re: Test OSU SB12: Thermocouples in CLI and CL3 (TF-107 and TF-103, Plots 5 and 9, respectively) show step decreases in temperature at about 6600 seconds. These do not appear to be associated with any liquid level changes in the cold legs (see Plots 103, 104). Explain this behavior.

Response

As indicated in Table 5.4.1-2, Matrix Test SB12 Inoperable Instruments / Invalid Data Channels, of the OSU TDR, the data from LDP-201 through LDP-206 was invalid due to the effect of the vemcal portion of the sense line which was attach to the top of the pipe. However, if the downcomer level compared with the 2mperature drop, it can be seen that the temperature decrease is associated with dowv.omer level approaching the cold leg elevation. SSAR Revision: NONE 1 l 480.264-1

NRC REQUEST FOR ADDITIONAL INFORMATION Question 480.265 Re: Test OSU SB12: Why do CL2 and CL4 (Plots 105,106) partially refill between about 2500 and 5000 seconds? They then appear to empty, even though the vessel and downcomer levels continue to rise.

Response

As indicated in Table 5.4.12, Matrix Test SB12 Inoperable Instniments/ Invalid Data Channels, of Reference 480.265-1, the data from LDP-201 through LDP-206 was invalid due to the effect of the vertical portion of the sense line which was attach to the top of the pipe. Once the pipe began to drain, this portion of the sense line drained resulting in invalid level indications. Reference 480.265-1 WCAP-14252, "AP600 Low Pressure Integral System Test at Oregon State University: Final Data Report," Proprietary [LTCT-T2R 100), May 1995. SSAR Revision: NONE I 4ao.as-i

NRC REQUEST FOR ADDmONAL INFORMATION Question 480.266 Re: Test OSU SB12: Why to the hot legs (Plots 101,102) appear to refill to a level above their initial values?

Response

As indicated in Table 5.4.12, Matrix Test SB12 Inoperable Instruments / Invalid Data Channels, of the OSU TDR, the data from LDP-201 through LDP-206 was invalid due to the effect of the vertical portion of the sense line which was attach to the top of the pipe. Once the pipe began to drain, this portion of the sense line drained resulting in invalid level indications. SSAR Revision: NONE 480.2M-1

~- l NRC REQUEST FOR ADDITIONAL INFORMATION Question 480.271 1 Re: Test OSU SBl4: Why are the initial levels different on Plot 110 (comparison of LDP-ll5 from tests SBl4 and HS-03)?

Response

As stated in section 2.4.3.1 of Reference 480.271-1, LDPs measure fluid level between the upper reference leg tap and the lower variable leg tap of a component. Flow in a component creates a dynamic differential pressure due to the pressure loss beween the component LDP taps as fluid flows through the component. When this dynamic component of differential pressure is superimposed on the static differential pressure, the resulting transmitter signal produce invalid data. Therefore, the LDPs in the vessel during flowing conditions should not be used directly. Reference 480.271-1 WCAP-14252, "AP6001.4w Pressure Integral System Test at Oregon State University: Final Data Report," Proprietary (LTCT-T2R 100), May 1995. SSAR Revision: NONE 480.271-1 -}}

ML20094H907

Contents

Text

SUBJECT:

Dear Mr. Quay:

Response

References:

References:

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Navigation menu

ML20094H907

Text

SUBJECT:

Dear Mr. Quay:

Response

References:

References:

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Response

Navigation menu

Search