ML20128C786

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Summary of 740919 Meeting W/Util in Bethesda,Md Re Reg Guides 1.3 & 1.7 Relative to post-accident Combustible Gas Control Requirements for Plant Containment
ML20128C786
Person / Time
Site: Monticello Xcel Energy icon.png
Issue date: 10/03/1974
From: James Shea
US ATOMIC ENERGY COMMISSION (AEC)
To:
US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9212040530
Download: ML20128C786 (3)


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Docket No. 50-263 02M LIGNSEE: NORTHERN STATES POWER COMPANY FACILITY: MONTICELLO NUCLEAR POWER PLANT MINUTES OF MEETIlt3 WITH NORTHERN STATES POWER (NSP) C(MPANT REPRESENTATIVES

" POST ACCIDENT COMBUSTIBLE CAS CONTROL" AT THE MONTICELLO WUCLEAR POWER PLANT AEC - Licensing representatives met with NSP representatives in Bethesda, Maryland on September 19, 1974 to review Reg Guide 1.3 and 1.7 relative to post accident combustible gas control requirements for the Monticello containment. NSP has demonstrated that the containment oxygen concentration can be maintained below the 5 w/o neximum oxygen concentration specified in the Monticello Technical Specifications and plane to submit a proposal to lower the technical specification marin=== oxygen concentration in the containment structure (drywall and wetwell - torus) to 3 w/o. In con-junction with this change, an additional 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to inert and deinert will be requestad as a technical specification limit.

h technical specification change, according to NSP calculations will allow for poet IRA radiolysis of water and the resultant formation of hy-drogen and oxygem for 22.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> in the wetwell and 83.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> in the drywell before oxygen concentration increases to 5 v/o and containment purging (using microgen) to the atmosphere most be initiated to remain

' within the 5 v/o oxygem limit, h controlled release of radioactivity from the contaf ====t results in a thyroid dose, secording to NSP, of 148 rem (30 day release period at the nearest outer boundary of the low population sons [3218. metere]). h loss of coolent accident (LOCA) thyroid dose reported in the NSP - Final Safety Analysis Report (FSAR) is 18 rem and therefore the total dose is 166 rem well below the 10 CFR Part 100 guideline of 300 ram.

N Regulatory staff calculated a thyroid dose of 3 ren for the LOCA for the Monticello Nuclear Generating Plant Unit 1 (safety evaluation dated March 18, 1970) wheresa the NSP-PSAR value is reported ar 18 rem.

With this higher value and the ESP calculated purge dose the resultant a

total dose would be 298 ren, very close to the 300 rum guideline. To resolve this calculational discrepancy it was agreed that NSP would provide recently obtained meteorological data for possible use by the AEC and both NSP and AEC would re-enmone the containment leakage dose calculations to identify and justify any differences in calculational methode.

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2- 007 g 3 374 It was agreed that soonas to category 1 connections nuest be provided for nitrogen purging in the post accident atmosphere sonsidering the potential for station operating personnel radiation orposure.

With respect to post accident containment gas and fission product monitoring, it was stated by AEC representatives that continuous monitoring of R2, 02s and radio-iodine is required and containment grab sampling, as proposed by NSP, is a suitable backup or redundant method to obtain the required post accident information. It was understood that the information, with confirmed accuracy, must be available prior to the earliest calculated purge time, i.e. , 22.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

A list of meeting attendees is included.

c James J. Shaa Operating Reactors Branch f2 Directorate of Licensing

Enclosure:

Attendance List DISTRIBUTION:

Docket ec w/enell

- es ng AEC PDR JShea l Iceal PDR ** "E l RP Assistant Directors RP Branch Oniafs

! 8. Varga T. J. Carter F. Schroeder TR Assistant Directors i

TR Branch Chiefs l

R. Bevan E Kaufman, OGC R0 (3)

R. R Digge R. F. Fralay, ACRS (16)

Meeting Attendees from REG i

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