ML19326C902
| ML19326C902 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/08/1975 |
| From: | Suhrke K BABCOCK & WILCOX CO. |
| To: | |
| References | |
| NUDOCS 8004280823 | |
| Download: ML19326C902 (7) | |
Text
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CE. 00O!'. & 's'.fi!COX Power Generation Grcus P.O. Box 1260, Lynchburg, Va. 24505 Telephone: (804) 384-5111 May 8,1975 Dr. Donald F. Knuth, Director Office of Inspection and Enforecment THIS DOCUMENT CONTAIN3 U.S. Nuclear Regula tory Consission P00R QUALITY.PAGES Washington, D.C.
20555
Dear Dr. Knuth:
/
Attached are ten copies of the report on the preliminary evaluation of the Sigtrificant Deficiency identified in the performance of the Sodium Thiosulfate Reactor Building Spray System.
Due to the variations in the details of the Reactor Building Spray System as-built design and operation between the various plants, ve can only indicate evaluations of the performance cf the individual, es-built systems is required to determine if a problem does exist.
We vill keep you informed of our progress in future eval"Maae
^#
the individuel a,y s i e w s.
Shuulu yvu require additionel inf ormation en en:.: cuuject, piccsc real f ree to contact either R.R. Steinke, Licensing Unit Manager, or R.P. Williamson,
. the cognizant Licensing Engineer for Significant Deficiencies.
Very truly yours, BABC0CK & WILCOX COMAPNY Nuclear Power Generation fh L
KES/bem Kenneth E. Suhrke Attach.
Manager, Licensing cc:
A. Schwencer IHIS DOCUMENT CONTAINS POOR QUALITY PAGES 8004280 23 J
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neport oa Sodi..a gior.uilate Spray System This report is being made pursuant to 10 CFR 50.55(c) on Significant Defici-encien to cl..curen t the in.matinctiun of a possible S:.gnificant Deficiency in the hydranslic performance of the Sodium Thiosulfate Reactor Building Spray (ISS)
Syr. tom.
Identification-of problem Analysis of the hydraulic perforr:ance of a RBS System using a newly developed con:puter code, "SURET 2", has revealed that as stas.cd in the FSAR.
the tanks do not drau down und formly Analycic A computer code, "SnOET 2", was used to analyze the hydraulic pc formance of the RDS System under accident conditions.
becauce the R"S Syctem piping inforn:ation was readily available.ANO--I was chose The input was tal.cn from M. W. Kellogg iso.ctric piping drawingn, the vendor's head vercus capacity curves for the installed pumps, ECCS analysis results in the FSAR, B6W equipment drawings, and the tank levels and concentratious as shown in Table 1.
The LPI pumps unre asnu::md to be prevented from execeding their rated runout capacity by the cavitating venturis in N40-1 LPI System.
The llPI pumps ucre assumed in the analyses to be prethrottled to prevent exceeding their rated runout <np>c!ty.
'ihe accident sualyacd w.c the LOC'.. - Othe R
' '.1, M M e a' in Use not leg or tne Reactor Coolant Syster.
The hydraulic performance uns analyzed for the two hender (2 RCS, 2 LPI and 2 HPI pumps) and ene hecdcr (1 RUS 1 LPI and 1 Hpl pump) cases.
The one header case, uhich could result if a dicsc1 generator failed to start, was included because NRC uses the one header cace for its evaluation.
Ranults The hydraulic results for the piping cystem analy zed show that:
1.
The Sodium Hydroxide and the Sodium Thiosulfate tanks emptied before the BNST.
Thus, there is no thiosulfate or hydroxide in the RSS from the time the _ two chemical tanks empty until the RDS pump suction is suitched
[
to the RB sump (recirculation period).
suction to the RE sump when the BWST low-low level alarm sounds.The ope
' Allowing 5 minutes for operator action, the time period during which the RitS does not have thiosulfate or hydroxide could be as long as 21 minutes.
The renults for cach cane are shown in Figuren 1 and 2.
- 2. 'For the tuo header canc. - the pil of the spray nolution it hetueen 10 and ll up to'1300 seconds (s 22 minutes).
Data preacntly available to St.W on paint' and other material compatibility testing only covers pil's up to 9.5.
For the one hendor n.sc, precine pu values are not available, bot the es timated 'pH'n serin t o be slir.h*1y hir.her (a few tenths of a pit uutt) than th0 t vo header cam-an d t he h i r.h pH cen dil l on se...: to last ahoo:
Lulee a.; long (see l'igni e 2).
N
%e hydr:ini i c p,va nt.cr - for each i.ni t vi th du SMi e n w ny e y mm differ.
Thus, the rpeci fic hydraulic performance discuuued in this report
- hould only bs. cQ:cidered applicabic to the sys te::. anaJ yaed.
Saiotv Evaluation This dev.8.ation in hydraulle performance is considered to represent a Significant Deficiency, purnimat to 10 CFR 50.55 (c), because:
There is a signif.icant deviation from the performance specified in the FSAR in that the two chetaical additive tanku and the liUST do not all draw down together under calculated accident conditions.
This_ deviation in performance could result in either or both of the following adverse effects following a LOCA:
1.
The analysis of radiation releases for an individual plan't pay show that the off-site doses are higher than those presented in the FSAR.
An evaluation uns performed by D&U to determine the dose impact on the
'resulting RUS System hydraulic performance.
A paraceter study was performed using a typical reactor building to determine the relative increase in thyroid dose as the period withcut chneical n'dditivcu in the spray was increased.
%e fission products were assu:ued to be released in accordance with Regulatory Guide 1.4.
The results are shotm in Tahic 2.
As shoun in Table 2, the lack of thiosulfate in the spray solution for a 15 to 20 r.tinute period cccurring sena 20 to 30 m.inutes follcwing the LOCA has very little effect on the thyroid dose.
2.
The pit of the RBS solution may, for a short period, exceed the value of 9.5 stated in B&W~ Topical Report DAW-10017, Rev. 1, "S tability and Compatibility of Sodium Thiosulfate Spray Solution - R&D Rcport (PROPR1r.TARY). "
Prelintinary information f rom coating suppliers indicates that a short duration exposure in the 11-12 pl! range would not damage the coating systecs Corrective Actions B&W has notified each of the affceted licensees that the liydraulic performance of the RUS Sysrem is sensitive to the as-huilt pipinp, configuration and has recommended that each licensee.iffected assure that the sys tma pe r fo rms w it.h in the criteria stated in the TSA!' or that the effects of the deviations fron specified performance are not udveruc.
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TABLE 1.
INITIAL TANK PARMETERS Tank Level (ft)
Chemical Comoositicn. We %
Specific Gravity BUST 39.06 1.3 Boric Acid 1.0 NaOH 33.125 14.8 NaOH 1.2 Thiosulfate -
33.125 20.6 Thiosulfate
)
-1. 3 Boric Acid
)
1.2 '
0.54 NaOH
)
l TABLE 2.
RELATIVE TdYROID DOSE RESULTS Period with D/Do Boric Acid BAN-10024*
Reg. Guide 1.4**
Spray (Min) 2 Headers 1 Header 2 Headers-1 Hender 0
1.0 1.6 2.1 2.7 6
1.0 1.6 2.2 2.7 12 1.0 1.6 2.2 2.'7 18 1.0 1.7 2.2 2.8 21 1.0 1.7 2.2-2.8
- Iodine Fractions - 98% elemental, 2% organic; from B&W Topical Report BAR-10024, "Zffectiveness of Sodium Thiosulfate Sprays for Iodine Removal."
G* Iodine Fractions - 91% elemental, 4% organic, 5% particulate; from Regulatory Guide 1.4, "Assumptior.s Used for Evaluating the Potehtial Radiological Consequences of a Losc of Coolaat Accident for Pressurized
. Water Reactors."
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FIliURE 1 TANK DRAWDOWN FOLLOWING A LOCA 40
-TWO SPRAY HEADERS OPERATING-BWST Level 30 Sodium 20 Hydroxide aj and a
Thiosul f a te c
No Tniosulfate Levels f
in Spray 7 Min 10 Switch to R e cir c. Mode
\\
c BWST Low-Low N
5 Min Level Alarm
\\
s
\\i\\
0 i
i 0
500 1000 1500 2000 Tima, Sec
FIGURE 2 TANK ORAWOOWN l'OLLOWING A LOCA WITH 40 ONE SPRAY HEAD OPERATING n
BWST Level
\\
30.
p NaOH J
Level f
\\
d
\\
32 T"i - a" >
x c
E 2
g No Thiosulphate i
N in RB Spray 21 Min
\\
\\
Switch to
\\
N'
/
Recir. Mode 10 5 Min.
BWST Low-Low
\\\\
c Level Alarm
\\
-\\
NN N
O O
1000 2000 3000 4000 5000 Tf.me, sec
.