ML19319E526
| ML19319E526 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/08/1975 |
| From: | BABCOCK & WILCOX CO. |
| To: | |
| Shared Package | |
| ML19319E524 | List: |
| References | |
| NUDOCS 8004110793 | |
| Download: ML19319E526 (6) | |
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V I:epot t. ott Sodie. : Wiosultate Spray System This report is being made pursuant to 10 CFR 50.55(c) on Significant Defici-encien to di.t:nr:. nt ti.e in.cuti",ation of a possible Significant Deficicuey in the hydraulic performance o.f the Sodium Riosulfate Reactor Building Spray (RBS)
System.
Identificat. ion of Problem
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Analysis of the ltydraulic performance of a RBS System using a newly developed "SYiGIET 2", has revealed that the tanks do not draw down uniformly computer code, as stated in the FSAR.
_Analysin A computer code, "SYl@'ET 2", was used to analyze the hydraulic performance of the RDS System under accident conditions.
becauce the RBS System piping information was readily available.ANO-1 was chosen The input was talen froci M. W. Kellogg isometric piping drawings, the vendor's head vercus capacity. curves for the installed pumps, ECCS analysis results in the FSAR, B&W equipn.cnt drawings, and the tank levcis and concentrations as shown in Table 1.
The LPI pumps were assu:md to be prevented from execedlug their rated runout capacity by the cavitating venturis in ANO-1 LPI System.
The HPI pumps were assumed in the analyses to be prethrottled to prevent execeding their rated p
runout enpaefty. We accident a. aly.cd.mn the LOCA. ~"0 :1 ' "w a
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in.uA 16. dic act leu oi tne Reactor Coolant Syster.
The hydraulic performance was analyzed for the two headar (2 13S, 2 LPI and 2 HpI pumps) and one hecdcr (1 RUS,1 LPI and 1 HPI pump) cases.
The one header case, which could result if a dicoc1 generator failed to start, was included because NRC uses the one header caso for its evaluation.
Ranults i
t The hydraulic results for the piping system analyzed show that:
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1.
De Sodium Hydroxide and the Sodium Thiosulfate tanks emptied before the BWST.
Thus, there is no thiosulfate or hydroxide in the RBS from the e
time the two chemical tanks empty until the RBS pump suction is suitched
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suction to the RB sump when the BWST low-low level alarm sounds.The operat
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to the RB sump (recirculation period).
Allowing 5 minutes for operator' action, the time period during which the RBS does not have thiosulfate or h droxide could be as long as 21 minutes.
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'Inc results for cach case are shown in Figuren 1 and 2.
2.
For the run header cane, the pil of the spray solution in between 10 and 11 up to 1300 seconds (+ 22 minutes).
Data presently availabic to BIM on palut and other material compatibility testing only covers pil's up to 9.5.
rnr the cue header cane, precine pil values are not available, bot the estimated pil's seem t o be niinhtly higher (a few tenths of a pil unit) than Ihe two header c.u:e and tiie h!nh pt! cenditIon accun to last about
.fm) v' tulee na long (see Fignte 2).
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k T1e hydran11c parametern for each unit with the Sodium Tdor.n1 fate RP.S Syr. ten differ.
Thus, the specific hydraulic performance discussed in this report should only be considered applicable to the syutem tuialy::cd.
Safety Evaluation This deviation in hydraulle performance is considered to represent a Significant Deficiency, purnuant to 10 CFR 50.55 (c), because:
There is a significant deviation from the performance specified in the FSAR in that the two chemical additive tanks and the BUST do not all draw down together under calculated accident conditions.
This deviation in performanen.could result in either or both of the following adverse offects following a LOCA:
1.
The analysis of radiation releases for an individual plant may show that the of f-site doses are higher than those presented in the FSAR.
An evaluation una performad by B&U to determine the dose impact on the
'rcsulting RES System hydraulic performance.
A paraceter study was performed using a typical reactor buildlug to determine the relative increcsc in thyroid dose as the period without chemical additives in the spray was increased.
The fission products were assumed to be released 7
-w, in accordance with. Regulatory Guide 1.4.
The results are shown in Ta'vic 2.
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As shown in Tabic 2, the lack of thiosulfate in the spray solution for a 15 to 20 minute period cccurring sona 20 to 30 minutes following the LOCA has very little effect on the thyroid dose.
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The pil of the RBS solution may, for a short period exceed the value of i
9.5 stated in B&W' Topical Report BAW-10017, Rev.1, " Stability and 3
Compatibility of Sodium Thiosulfate Spray Solution - R&D Report (PROPRIETARY)."
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Preliminary information from coating suppliers indicates that a short duration exposure in the 11-12 pil range would not damage the coating systems.
Corrective Actions
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B&W has notified each of the affceted licennees that the hydrnulic performance of the RUS Sycrem is sensitive to the au-huilt piping configuration and has recommended that each licensee affected assure that the system performs wi. thin the criteria stated in the PSAR or that the ef fects of the deviations fron specified perfocaunce are not adverse.
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l Planen Affected TNT-1
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Operatitig Licenses j
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Crystal 1:1ver-3 )
Construction Permits 4
Midland 1, 2
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TABLE 1.
INITIAL TANK PARA!!ETERS Tank Level (ft)
Chemical Composition, We %
Specific Cravity BWST 39.06 143 Boric Acid 1.0 NaOH 33.125 14.8 NaOH 1.2 Thiosulfate 33.125 20.6 'Ihiosulfate
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1.3 Boric Acid
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1.2 0.54 NaOH
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TABLE 2.
RELATIVE THYROID DOSE RESULTS Period with D/Do Boric Acid BAW-10024*
Reg. Guide 1.4**
Spray (Min) 2 Headers 1 Header 2 Headers 1 Header 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 BAW-10024, " Effectiveness of Sodium Thiosulfate Sprays for Iodine Removal."
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- Iodine Fractions - 91% elemental, 4% organic, 5% particulate; from Regulatory Guide 1.4, " Assumptions Used for Evaluating the Potential Radiological Consequences of a Loss of Coolant Accident for Pressurized Water Reactors."
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FbreRE 1 TANK DRAWDOHN FOLLOWING A LOCA 40
-TWO SPRAY HEADERS OPERATING-BWST Level N
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30 U
Sodium 20 Hydroxide and x
Thiosulfate No Thiosulfate E
Levels g.
In Spray 7 Min 10 Switch to gecirc. Mo@j
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BWST Low-Low Level Alarm
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500 1000 1500 2000 Tima, Sec l
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FIGURE 2 TANK ORAWOOWN FOLLOWING A LOCA WITH
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ONE SPRAY HEA0 OPERATING BWST Level 30 NaOH Level f
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g 20 Thiosulphate
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j Level c
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No Thiosulphate N
in RB Spray 21 Min N
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1 Switch to
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Recir. Mode
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10 5 Min.
BWST Low-Low
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Level Alarm
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k N'N N
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O 1000 2000 3000 4000 5000 Ti.me, sec 8
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