ML20126C216

Responds to Continuation of ORB-2-210 - Monticello Spent Fuel Cask Drop

ML20126C216
Person / Time
Site:	Monticello
Issue date:	03/22/1976
From:	Eisenhut D Office of Nuclear Reactor Regulation
To:	Goller K Office of Nuclear Reactor Regulation
References
NUDOCS 9212220424
Download: ML20126C216 (4)

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i K. Coller, Assistant Director for Operating Reactors RESPONSE TO CONTINUATION OP ORB-2-210 - MohTICELLO SPENT FUEL CASK DROP i

J (TAR 3383)

PLANT MAMEt Montice h DOCKET NUMBER: _50i2h3. '

RESPON3IBLE BRANCH: ORD-2 PROJECT MANAGEkt R. Snaider REQUEST RECEIVED BY EEB: March 5, 1976 REQUESTED COMPLETION DATE: March 15, 1976 REVIEW STATUS: Complete The consequence of dropping a spent fuel shipping cask down the equipment i hatch have bo #1 6 W l4 i.o be wall within 10 CFR Part 100 guidelines (see

! attached) . t wm. , ' ~. ,f a J nr. dif f erences in initial inventories appear 8

, betveau these s w.4 @ fxn 2 hose performed by the licensee. These i dif ferences ath 3 (# $6 e% result of licensee's using the distribution of nuclides in sbm w1 as presented in GESEAR and the staf f's using accident source teries eseyed to 90 days and 120 days. These differences do not affect our concluaica that the consequences would be small. The dropped cask was asewned net to violate the integrity of the reactor building and thus bypass the stack. This should be confirmed by the ORPH.

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icenho D. EisenS[ut, Assistant Director for Operational Technology Division of Operating Reactors Office of Nuclear Reactor Regulation Enclosuret As stated 1

cel V. Stallo DISTRIBUTION:

D. Ziesmann / Docket R. Snaider NRR/ Reading l B. Grinas EEB/ Reading 1 E. Adensam i

OT B/C's OILE OELD ) MN /J 0"* . - . .AD 1 - .

. . _ , _ EEB/d E.Adensen "9.1. r es et . _

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i Form Atc.316 (Rev 9 53) AECM 0240 W u. e. novsakusut emswfine orrecas sers eno.ses 9212220424 760322 PDR ADOCK 03000263 P PDR

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! I ESTINATES OF DOSE CONSEQUENCES FROH d

A SPENT FUEL CASK DROP AT ENTICELLO i I j A spent fuel cask containing two 7 x 7 spent fuel assemblies is assumed  ;

1 dropped down a hatchway in such a manner that the cask fails and all the ,

i j fuel pins (rods) are ruptured. The cask is assumed to not violate the. l i

reactor building integrity. The gap activity of halogens and noble gases l is assumed released in a puff to the standby gas treatment system filter l and to the plant stack. Fumigation conditions are assumed. Table 1 1

1 itemizes all the assumptions made, and Table 2 presents the results..

l The initial activity in the fuel assemblies was calculated assuming peak

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' equilibrium levels in .ha' t ~fuel except Kr85 which was calculated assuming

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j. a 3-year operating time at full power. No contribution due to decaying 4

parents was assumed. The consequences estimated are we11'within the

. guidelinas of 10 CFR Part 100. . .

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TABLE 1 ASSUMPTIONS FOR SPENT FUEL CASK DROP AT MONTICELLO Power level 1670 Mwt Operating tima 3 years Power peaking 1.5 Decay times 90 days; 120 days Fraction in gapst Kr-85 30%

All other noble gases 10%

Iodine 10% .

Filter efficiency for iodine 90%

Number of rods damaged 98

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__. Number of rods in core .23 716

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Initial inventories at time of shutdown: - -

I-131 - ~ ~ ~ 25,080 ci/Mwt.

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ge_131.

. .. A ,f. 299.5 ci/Mwt ..-*

Gi. -- . . Ie-133'

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Kr-85 410.2 ci/Mwt Breathing rate 3.47 x 10-4 .m3 /sec

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TABLE 2 ESTIMATED DOSE CONSEQUENCES FROM A SPENT' FUEL CASK DROP AT HONTICELLO Dose, rem Distance Thyroid 5 cm depth dose, y* .7 ma/cm2 skin dose. 8 + y**

at 120 days 500 meters 8.9 x 10'3 1.3 x 10-4 1.07 x 10-2 1609 meters 3.5 x 10'3 5.2 x 10-5 4.2 x 10~3 at 90 days 500 meters 1.2 x 10'1 1.5 x 10~4 1.08 x 10-2 1609 meters 4.6 x 10-2 -

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