ML20128D825

Advises That off-gas Assessment Accident Performed by Accident Analysis Branch,Dtd 730911,has Been Revised to Account for Changes in Two Parameters Used in Calculation

ML20128D825
Person / Time
Site:	Monticello
Issue date:	10/11/1973
From:	Harold Denton US ATOMIC ENERGY COMMISSION (AEC)
To:	Skovholt D US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9212070395
Download: ML20128D825 (3)

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l L-AD/SS L-AAB g- [ OCT 1 1 1973 D. Skovholt, Assistant Director for Operating Reactors, L OFF-CAS SYSTEM ACCIDENT ASSESSMENT REVISION FOR MONTICELLO TAR-590 (MEMO i2)

The off-gas assessment accident performed by the Accident Analysis Branch (AAB) for the Monticello Plant dated September 11, 1973, has been revised to account for changes in two parameters used in the calculation. The condenser leak rete has been revised from 28 SCFil to 20 SCFM and the delay time to tank has been revised from 30 minutes (.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) to 330 minutes (5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />). Theso changes were transmitted to the AAB by Operating Reactors (OR) and are reflected in Tabis 1. All other assumptions remain un-changed. Table 2 provides the revised calculated doses.

Operating Reactors has indicated that the hold-up tanks at Monticello are designed to seismic category standards. If the tanks contain suitable isolation characteristics such that a failure of the off-gas system will not result in total loss of the contents of the hold-up tanks then the off-gas release rate should be set as a function of the dose contributions from the steam jet air ejector (SJAE) and the colg D aa. If isolation of the hold-up tanks cannot be shown, then the off-gas release rate should be set as a function of the dose contribution from the SJAE the delay line and the hold-up tanks. The release rate for isolated and non-isolated hold-up tanks is listed in Table 2.

The allowabic release rates may be adjusted if safety grade automatic isolation of the SJAE is provided.

This Branch.

work was performed by Joel E. -Kohler of the Accident Analysis Ods;inal signed by

11. H. Denke liarold R. Denton, Assistant Director j for Site Safety Directorate of Licensing Enclosure i Table 1 Table 2-CC i W/D sucA.

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OJF-GAS _ ACCIDENT REVISED ASSUMPTIONS.  ;

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Revised Power Level (MWt) 1630

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i Number of Units Using ,

' 1 Common Delay Line 4

1 Condenser Leak Rate (SCfH) _28 20 i Humber of Iloid-Up Tanks 5

] Iloid-Up Time per Tank (hrs.) 12 ,

1 l Delay Time to Tank (min.) 30 (.5 hrn.) _

330 (5.5 hroj, 1

! Noble Gas Release Rate (after 30 minute delay) (uci/sec) 350,000 i

lodine nelease Rate (uci/sec) .5 Safety Culde 3 Heteorology i (sec/m3 ) 2.0 X 10~3 Minimum Site Boundary (meters) 500 Accident Duration (hrs.) 2

'h Isolation Time for Steam Jet Air Ejector (hrs.) 1 I

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M TAllLE 2 .

TWO 110VR SITE lt0UNDAltY DOSE (50 meters) i

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, Wole Body Dose , Revised Wole Body Dose 1

Steam Jet Air Ejector 3.10 3.10 )

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Delay Line .569 2.33 Tank 1 1.92 .819 1

Tank 2 .418 .302 Tank 3 .214 .176 Tank 4 .142 .126 4 Tank 5 .111 .102 l -TOTAL 6.47

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Release Rate (seismic 1, isolating hold-up tanks) 320,000 uCi/sec a

4 Release Rate (seismic 1, non-isolating hold-up tanks) 250,000 uCi/sec l' .

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