ML20008D789

App 14A to Midland 1 & 2 PSAR, Chemical Sprays. Includes Revisions 1-36

ML20008D789
Person / Time
Site:	Midland
Issue date:	01/13/1969
From:	CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
References
NUDOCS 8007300705
Download: ML20008D789 (4)

Text

, - - - .

D d APPENDIX lhA CHE4ICAL SPPAYS INTRODUCTION A chemical additive has been added to the reactor building spray for the purpose cf re=cving any radioactive iodine which cay be released folleving a less-of-coolant accident. The chemical spray solution is a boric acid solution containing sodiu= thiosulfate and enough sodiu= hydroxide to for=

an alkaline pH buffer with the %cric acid. This solution co= position is cc=-

=cnly referred to as " alkaline suw.u:.1 thiosulfate. "

J The sodiu: thiosu] Nte in the alkaline sodium thiosulfate solution reacts rap-idly, co=pletely, a irreversibly with iodine, and was, in fact, suggested by Griffith(1) in his 15c3 study en the use of sprays for re=oving iodine frc=

reactor building at=cspheres. The sodium hydroxide is not intended to play an active role in the absorption of iodine; its function is =erely to preserve the long-tem the desiredstability pH. of the alkaline sodiu= thiosulfate solutien by =aintaining Data p esently available (2-7) indicate that the alkaline sodiu= thiosulfate 1

solution is satisfactory when used in a properly engineered syste=.

IODITE RD! OVAL EFFECTIVENESS ORNL (NSPP)has conducted facility. These tests, a nu=ber of spray as reported in ORNL tests in the Nuclear) h253(7 Safety Pilot Plant

, have de=enstrated that elemental radicactive iodine is rapidly recoved by chemical sprays.

' Using an NSPP run =ade at accident conditions closely approxi=ating those pre-dicted for Midland Units 1 and 2, the =easured iodine half-life was 31 seconds; that is, half of the radioactive iodine was re=oved fro = the Jtea=-air atmos-phere in 31 seconds after starting the sprays. These data haw been scaled to

' the Midland Units 1 and 2 design. They result in an iodine h C life of 28 seconds with the full spray installed capacity operating (2350 sp=) and a half-life of 56 seconds at half capacity. The iodine half-life reported in Section 14.2.2 3 7 is 61 seconds at full capacity and 121 seconds at half capacity.

A large number of confirmatcry tests (T-12) have been =ade which demonstrate that che=ical sprays are effective for ied' 'e re= oval. These spray tests have been

=ade using a vide range of variables - spray distributions with droplet sizes ranging frc= 100 to 1200 =icrons, fall heights ranging from a few feet to approxi=ately 50 feet, temperature and pressure conditions varying from a=bient to =ax1=u= accident conditions, iodine concentrations ranging fro = 1 to 130

=g/ cubic ceter, single and multiple spray nozzle installations, spray fluxes ranging frec O.007 to 0.2 gra per square foot vessel cross section, and cen-densing and noncondensing conditions. With this vide range of confir=atory

. test conditions, we are confident that the Midland Units 1 and 2 che=im spray syste=s vill perfom as predicted, b.

V 0 0 0 ?S 800730076f lhA-1 A=end=ent No. 5 11/3/69 3 ,,, - . . -.oi , - .

y 1m y .-- -, , ws.,e - , , , , -

,.,.e ..,n . ,,-

l' t .

ORGANIC ICDINE

, i The organic iodine consists pri=arily of = ethyl iodide but includes a s=all,

, al= cst insignificant, fraction of cther organic iodides. '

i Experimental data obtained under a vide variety of conditions en the amount of

' = ethyl iodide released frc= overheated fuel are repcrted in nu=ercus publica-tiens. Iodine release experiments using irradiated Zircalcy-clad UO, fuel in a

inPWR accident Section 1h.2.2 environment 3 7 Six tests show (13 1-ss)than were the perfor=ed 5 percent at organic Battelle1"orthwest di?.e assu=ed

Laboratories.

organic for=. They found that 1 percent er less cf airborne iodine (ggg in the Thirteen other experi=ents were perfor:ed in England /; all but two shov less than 0.2 percent as = ethyl iodide. The highest result was 1

3 percent. There are a number of other experiments reported in the literature which deal with the a= cunt of nonreactive iodine released frc= overheated fuel.

Sc=e of these experiments have observed greater than 5 percent nonrecovable iodine; however, these experiments were conducted under conditions that are not applicable to the PWR accident environment. It is en the basis of all the

} data above that we concluded that 5 percent nonre=ovable iodine was a conserva-tive value for use in the accident analysis. l Spray tests at Oak Ridge National Laboratcry(7,15) and Battelle-Northwest Laboratory (16) have de=enstrated that alkaline sodium thiosulfate spray is ef-fective for re= oval of methyl iodide. While the removal rate is not as dra:atic as that for ele = ental iodine, the methyl iodine re= oval rate is sufficient to

'} =ake a significant reduction in the airborne iodine eencentration and thus in I_

s_/ the off-site doses.

Spray test A-12 in the Contain=ent Systems Experiment (CSE)(16) de=cnstrated I that alkaline thicsulfate spray re=cves methyl iodine fro = a stea=-air environment with a half-life of 80 minutes. Scaling this to Midland Units 1 and 2 predicts a methyl iodide half-life of 52 minutes.

PARTICUIATE IODINE i

A s=all fraction of the iodine assumed to be roleased folleving the LOCA may attach to particles and dust to for= particulane aerosols. Several studies have shewn that, should the particulate aerosols be for:ed, they vill be rapidly re-moved frc= the reactor building at=osphere.

Stinchec=be and Goldsmith (II' 16) have shown that sub=icron particles are re=oved with 95 to 99 percent efficiency by condensing steam. They clso show that the ther=al and vapor presse-e gradients, which exist in the condensing stea= envi-ron=ent, drive the sub=icron particles tevard the eccler surfaces where they are re=oved frc= the atmosphere with the condensing water vapor.

I -

Particles greater than 0.2 =icron size are re=oved efficiently by impac+. ion with the reactor building spray; these particles less than 0.2 =icron size are not.

However, the s= aller particles serve as condensation nuclei which grow until gravitational and inertial forces result in rapid deposition of these par ticles. (17, 19) The absence of particles, after aging, de=enstrates the effee-gr "' tiveness of this removal =echanis=. Idkevise, ve; r s=all thermal gradients act g

l a l driving forces which caus9l migration of particles to the spray drop surfaces and thereby enhance removal.l 7) i 14A-2 00&&

A=endment No. 5 11/3/69 u,_ _, _ .u . _ _ _ . . _ , _ . _ _ . _ _ _ _ _ _ . _ . _ _ ~ . , _ . _ _ _ _ _ , . . . _ . _

1 1

l High ersteconcentrations of small(eO, 21) particles are very unstable and rapidly agglet-into larger particles.

j These are effectively removed by impac-tien with spray drops, by washout frc: the ecndensing stea=, and by settlement.

As a result, nearly all particulates are expected to be removed frc: the re-actor building atmosphere.

Experiments in the CSE(0) have de=enstrated rapid re= oval of particulates by I

spraying. These tests indicate removal rates in a condensing stea: enviren-cent - similar to that in the reactor buildi:2g following an LCCA - of cne third

-f to one half as fast as for elemental iodine.

HY?cICDCUS ACID Hypoicdous acid is a product of elemental iodine hydrolysis by alkaline aqueous solutions.(22) The addition of sodium thiosulfate to an alkaline solution pre-cludes formation of hypoiodcus acid in any significant a: cunt. Sodium thio-l i

sulfate reacts instantaneously with elemental iodine, reducing the iodine to iodide. Thus, no ele ental iodine is available for hydrolysis to the hypc-iodcus form.

REFERENCES (1) Griffith, V., The Removal of Iodine Fro the Atmosphere by Sprays, AHSB(S)R h5, 1963, pp 7-12.

i

! (2) Cottrell, W. B., ORNL Nuclear Safety Research and Develop =ent Program, Bicenthly Report for July-August 1967, OR%-TM-1986, p 35 (3) Cottrell, W. B., ORNL Nuclear Safety Research and Develop =ent Program, Bimonthly Report for March-April 1968, ORNL-TM-2230, p 81.

! (4) Cottrell, W. B., ORNL Nuclear Safety Research and Develop =ent Prcgram, '

i i

Bicenthly Report for May-June 1968, ORNL-m-2283, pp 6h-73 (5) Cottrell, W. B., ORNL Nuclear Safety Research and Develop =ent Program, i Bicenthly Report for July-August 1968, ORNL-m-2368, Section 3 5 (6) Cettrell, W. B., ORNL Nuclear Safety Research and Develop =ent Program, Annual Report for 1967, ORNL-h228.

(7) Parsley, L. F. and Franzreb, J. K., Re cval of Icdine Vapor From Air and f Stean-Air At=cspheres in the Nuclear Safety Pilot Plant by Use of Sprays, ORNL h253, June 1968.

(8) Nuclear Safety Quarterly Report; November, December 1967, January 1968; for Nuclear Safety Branch of USAEC Divisicn of Reactor Develcirent and Technology, b.v the Staff of Battelle-Northwest, BNWL-816.

i (9) Nuclear Safety Quarterly Report; February, March, April 1968; for Nuclear

' Safety Branch of USAEC Division of Reactor Develop =ent and Technology, by the Staff of lattelle-Northwest, BNWL-885 l O.

U oo M 14A-3 Amindment No. 5 11/3/69

- . - - - - . , - _ , ,_- .- -.,. _ .- - - .--.-. . - . _ _ - _ _ _ - . . - _ . . ~ .

I (10) j W.,

Sodium Thiosulfate Sprays, Reaction of Molecular IodineCRW.-h076, and of Methyl Iodid pe169With Parker, (11)

Nishizava, Y. , et al. , "A Study of the Re= oval of Iodine F phere No. by Sprays,'

11, November 19eo,Journal cf the pp 590-oC2. Japan Society of rem the Atmos-Nuclear Pever

, Vol 8, (12) Maekava, T., et al.,

I - Removal of Iodine by Sprav Under Atmospheric Press Ja9n Society of Nuclear Power, Vol 7, No.10, pp 563 ournal of the

, 1905569

- ~

(13) K.,

Coleman, L. F. and McCor:ack, J. D. , Co parison Centainment 2 Behavior of a Simulant ased With s of theFission Irradiated "C , ENL-581, March 1968, Table h, p A.5 .

From (lk)

J.,

Behavior April 1965 of Gas-Borne Iodine, Some TRG-R-983(W)

Experiments Relating t o the UKAEAC

, Windscale, England, (15) Parker, G. V., Creek, G.

E., and Horton, N. R., Dissolutio n and Hydrolysis Progress Report for Period Ending Decemberof Methyl Iod ram Annual (16) 31, 1967, CPlTL-h228, April 1968.

Nuclear Safety Quarterly Report; May, June, July 1969

( . Branch of published). USAEC Division of Reactor Development ogyand (to Technol, be for Nu (17)

P.,

by Condensing Steam," AERE-M-121h.Stinchcombe, " Removal of Iodine From AtmosphereR. A. and (18)

P.,

Stea=," Journal of Nuclear Energy

" Removal of IodineParts A/B, Vol 20Sti F rom Condensing (19) , pp 261-275, 1966.

G., "Diffusiophoresis and Them Vapor Syste=s," Aerosol Science, C. N. Davies, EdGo New York, New York, pp ophoresis in Water 163-194 (1 % 6). ., Academic Press, Inc. ,

(20) Collings, D. A.,

et al., " Experience in Trapping Iodine 131 -

andElements Other Fission Products Released From AGR-Type Fuel , -

, p 113

" TID 76 (21) Ke11holtz, G. W.,

Safeguards in Nuclear Installations," 0RNL-NSIC-13" eered Filters (22)

, p 139, October 1966.

Parsley, L. F. and Wantland, J. L. , " General Considerati Use of Sprays," pp 256-26h, Nuclear Safety Program ons I.garding Annual the P for Period Ending Dece=ter rogress Report 31,1968, ORNL-4373 .

\ 00043 lhA-h Amendment No. 5 11/3 /69