TMI-80-076, Forwards List of HPI Flows Used in Performing Core Flood Line Break Analysis & Writeup Re Applicability of HPI Flows Used in Small Break Analysis.Suggested Corrections to Table 1,Column B of Sys Design Description for HPI Encl

Forwards List of HPI Flows Used in Performing Core Flood Line Break Analysis & Writeup Re Applicability of HPI Flows Used in Small Break Analysis.Suggested Corrections to Table 1,Column B of Sys Design Description for HPI Encl

ML20112H244
Person / Time
Site:	Three Mile Island
Issue date:	04/16/1980
From:	Fairburn G BABCOCK & WILCOX CO.
To:	Slear D GENERAL PUBLIC UTILITIES CORP.
References
TLL-238, TMI-80-076, TMI-80-76, NUDOCS 8501170043
Download: ML20112H244 (7)

Text

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i e e,cenueorco Babcock &Wilcox ~

P.O. Scx 1260, Lin:ncurg, Va. i405 Telephene: (804) 384,5111 April 16, 1980 TMI-80-076 .

Mr. O. G. Slear (3)

TMI-I Project Engineering lianager GPU Service Corporation 100 Interpace Parkway Parsippany, flJ 07054

Subject:

HPI Flows'During Small' Break Transients ,

Dear Mr. Slear:

Attached for your information and use is the information-requested by your Mr. J. F. Fritzen and the NRC during a telecen on March 4,1980. Attachment A documents the HPI flows used by B&W in performing the core flood line beeak analysis. Attachment 8 provides a writeup concerning the applicability of the EPI flows used by BtW in tha small break cnalysis relative to the TMI Unit I HPI flows. Attachment C provides suggested corrections to Table 1, Column 8 of System Design Description for High Pressure Injection Cross-Connect, SDD 211A,.

Rev. 1.

If you have any questions or regulr,e additional information, please advise.

Very truly yours, ,

l j J l'...v! "

G. T. Fairburn Service Manager .

GTF/c.-

, cc: J. G. Herbein L. L. Lawyer J. J. Colitz -

J. F. Fritzen T. J. Tecle 4 . 't.' . Y.02 ton - GP'JSC F. R. Faist J. C. i.ewis - Philst Sales N 850ii7oog3g0y9 .

PDR ADOC PDR P

4 0 0 .

• • D

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g ATTAC1 DENT A

}TI Flovs I'oring CFT T.ine Break Flou. gpm Pressure, psia .

454.5 0.0 .

440. 615.

365. 1315.

340. 1515.

325. 1615.

325. 3000. .

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ATTACIDENT B_

Applica:allity of tha Sns11 Break T.tW Model to the TMI-1 Plant Characteristics

On ihrch 6, 1980, a joint telephone conversation took place with GPU, NRC,

=and B&W, concerning the TMI-1 HPI system. -The NRC raised the question of the ,

applicability of-the B&W small break model (references 1, 2, and 3) to TMI-1, since the flows delivered,by the THI-1 HPI system are lower than those assumed in the B&W analyses for pressures below 600 spig (reference 2).

.The HPI flows used by B&W are 1isted in the attached Table A. Flows in Column I are used for the first 10 minutes of the transient. Following manual cross-connecting of the HPI valves at this time, the flows in Column II are casumed for the remainder of the transient. 'The difference arises because, for a pressure of 0 psig, the THI-1 system delivers 500 gym instead of deliver-ing a flow equal to or greater than the 548 gpm analysis value. This is shown in Table A.

It should be pointed ou,t that the spectrum analyses documented in references 2 and 3 were performed at 27724pt, while the rated power of the 17E-1 plant ,

in 2535'MNt. Table B lists the HPI flows which should be used following operator action at 600 seconds, if the THI-1 initial core power vere modeled in order to calculate the same system responses presented in reference 2. It can be seen that at 0 psig, the HPI flow should be 501 gpm. Therefore, there is a discrepancy of culy 1 gpm, between the injection flow needed.at 0 psig, and the TMI-1 HPI flows ' delivered at that pressure.

In order to assess the impact of the smaller HPI flous in the analyses de-ceribed in reference 2, two of the cases presented there' have been re-evalu-2 ated using hand calculations. Specifically, the 0.15 ft break at pump dis-charge has been considered since this break depressurizes the system to 600 psig more quickly. Thesecondbreaktobestu11edwasthe0.07ft 2at pump discharge, which turned out to be the worst case.

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-Results of the 0.15 ft 2 at punp discharge srall 12 < a analysis show that the fprimary system pressure reaches 600 psig at about SCO seconds, i.e. , before

- the operator action (Figure 3,- reference 2). At this time the HPI pump is delivering 450 gpd (Table A, Column I), of which 502 enters the system, and the other 50% is lost through the break. This pressure also coincides with the actuation.of 2 core flood tanks, which, for this case, inject an average ~

of about 55 lbm/s of additional flow to the reactor vessel. Coreboil-o[ff id catched in the analysis at about 550 seconds.

The mixture height in the reactor vessel at this tine is about 1 f t above the top of the core. Following operator action at 600 seconds, which results in an increase of the flow delivered to the reactor vessel, the mixture level in the vessel starts to increase. Assuming .for conservatism, the small break '

model power of 2772 MWe, as opposed to 2535 MWe, the mixture level in .the .

vassel is estimated to increase at a slightly 'slouer rate than calculated in the analysis, due to the difference in HPI flows between the model and the .

THI-l plant. The core'never uncovers, thus preventing any cladding te=pera-ture excursion; assuring conformance with 10 CFR 50 46.

The 0.07 f t 2 break at P,D, which, in reference 2 was found to be the worst '

small break, resulted in a minor core '

uncovery and a peak cladding tempera-ture of 1095F, which is well below the 2200F criteria of 10 CFR 50.46. Figure 3 of reference 2 shows that the system reaches 600 psig at 'about 1500. seconds, which also corresponds to the minimum core mixture level (reference, Figure 4).

The top of the core is re-covered at about 1800 seconds. Using THI-1 flows, and the model core initial power of 2772 M:c, a deficiency of abobe 350 pounds l- of liquid water exists in the vessel at this time, as co: pared to liquid in-l

.; ventory calculated in the analysis. Because of this difference, the vessel

] refills to the top of the core with a 15 seconds delay. , Thus the peak temperature t

' rcesins in the neighborhood of 1100F, as calculated in reference 2, ensuring cor.pliance to the 10 CFR 50.46 criteria.

i 2

R:ference 3, Appendix C, documents a core flood tank line break (0.44 ft )

cnalysis, performed for a typical 177 low-loop plant, having an initial power

.cf 2772 tr.it. The HPI flows assumed in that analysis are lower than the RPI flows used in reference 2 (ceo Attachr.ent A). t. nin, the esiculated cystem . . ,

b y L.

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m .. .. . -_ __. ___ _ _ _ -._.. _..._ ... . _.. .. . _ . . . __. - :......

l ve. . _

ii

rcsponses iollcwing the-initiation of the transient cc= ply wholly with the

.;10 CFR 50.*46' criteria. .

In si'enary, the 'DII-1 IIPI systers, when used in a single failure mode'in an hypothisized small' break LOCA,-can safely mitigate the transient within the

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-liciitations of Appendix K.

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Table A. IIPI Flous Assumed in the tr?I 5:211 Break !!adel

. . Assuned HPI flows Assumed liPI flows the first 10 min af ter 10 min '

(50% is lost (30% is lost ,

Pressure, psig throuch the bresk) through the break) 0 515 -

548 ,,

600 450 500 1200 380 -

438 .

1500 342 -

404 1600 328 ,

391.7 i800 300 .,

364.3

• r 260.0 2400 210 ,

Table B

~

Assu::ed itPI fiou for T?!I-1 '- -

after 10 min (30% is lost Pressure, p'sig N through the breck)

. 0 501 '

600 457

• 1000 400

• 1300 369 2000 358 2400 333, .

2

_ REFERENCES N

1. T pical Report BA11-10104, Rev. 3, "B&}i's ECCS Evaluation Ifodel," August 1977.

• 2. Lotter from J.H. Taylor (B&W) to S. A. Varga (NRC), July 18,197S.

3. T pical, Report 3/d?-10103A, Rev. 3 "ECCS Analysis of B511's 177-FA .

..T.cected-Loop NSS," July 1977..

• ATTACHME!;T C

. Table 1. HPI Flot Requirements (

_ Column A Column B

Pump flote Pump floti RC pressure, psig undegraded, gpm degraded. epm ,

0 550. 515

• 600 500. 450 ,

1200

• 437.1 380 1500 404.3" '342.

1600 391.4 328 1800 364.3 300 2400 260 210 2500 -

216.0 191 7 (1)Only for small br,eak conditions other than a HPI line

• break. -

See refere'nce (0) for flote assumed under HPI line break conditions. -

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