ML19317D466

Ao:On 710803,release of Radioactive Liquid Into Sewage Retention Pond Resulted from Overflow of Unit 2 Facade Sump During Filling Operation.Caused by Problems W/Facade Drain

ML19317D466
Person / Time
Site:	Oconee, Point Beach
Issue date:	08/11/1971
From:	Burstein S WISCONSIN ELECTRIC POWER CO.
To:
Shared Package
ML19317D464	List: ML19317D466 ML19317D468
References
NUDOCS 7912030366
Download: ML19317D466 (2)

Text

. c,,, ,,

l , 0 - -

0 - - -'f ,. k/ l}

Q'[0lic= t AUG u1 6 C I-

s. g .

- <W2:(197t s?p,pr WiSCCDSin Electncmacouaw '

- r 231 WEST MICHIGAN, MILWAUKEE, WISCONSIN $3201

[

August 11, 1971 O

Dr. Peter A. Morris, Director

. Division of Reactor Licensing U.S. Atomic Energy Commission Washington, D.C. 20545

Dear Dr. Morris:

ABNORMAL OCCURRENCE FACILITY OPERATING LICENSE DPR-24 UNSCHEDULED RELEASE OF RADIOACTIVITY POINT BEACH NUCLEAR PLANT DOCKET NO. 50 - 265 This letter is to report the details of an abncraal occurrence at Point Beach Nuclear Plant which rescited ir an unscheduled release of radioactivity from the plant on At. gust 3, 1971. The release occurred when the Unit 2 refueling wa..er storage tank overflowed to the Unit 2 facade sump during a filling operation, with subsequent release of radioactive liquid to the sewage retention pond. This occurrence wa::. re-ported by telephone on August 3 to the Region III Compliz.nce Office. No Limiting Conditionc for cparation were violated.

At 0900 on August 3, 1971, filling of the Unit 2 refueling water storage tank was comx.enced using the.Unis. 1 -

reactor makeup water tank as a water source. The initia:. re-fueling water storage tank lovel was 79% by control room in-dication. The refueling water storage tank had previous..y been borated from a boric acid tank which contained some recyc. led boric acid from Unit 1 operation. At 1130 it was noted uhat the refueling water storage tank lavel indication had stopped at 81%. The Auxiliary Operar.or i.ho was sent to investig:.te found that the local indication was reading 100%, and the tank was. overflowing to the Unit 2 facade drain trough. The Shift Supervisor was informed immudiawly ca.d the filling was : topped.

The facade drain ..ns to the Unit 2 facade sump and, at the time of the acc urenca, the sump pump d: s-charge was lined up to the sewage tr u cment plant. Ther2 fore, the overflow from the refueling water storage tank was ulti- p mately released tu the sewage retention pond.

e2tE

e r' ,,

, . . .~ - - -

3 .

. . . .J J Dr. Potcr A. Morris Auguct 11, 1971 By reading the flow totalizer which indicates the quantity of makeup water used to fill the refueling water storage tank and comparing the initial and final level in-dicaticns of the refueling water storage tank, it was calcu-lated that approximately 6000 gallons of water overflowed the refueling water storage tank. An analysis of the residual water in the facade sump was made, and the following radio-activity levels. recorded:

• H 8 - 1.91 x 10-3 pCi/ml, Gross Sy - 3.56 x 10 'vCi/ml, I l31 - 3.31 x 10-8 pCi/ml, and Co S8 - 2 . 5 4 x 10 - 7 pCi/ml.

The aump radioactivity conceatrations were below tha maxi. lum permicsible concentration recuirements for release to a ra-The stricted area as listed in 10CFR20, Appendix B, Tabic I.

sump 's considered a restricted area. For purposes of measur-ing tne radioactivity concentrations for a release to unr2-stricted areas, a point at the inlet of the retencien poni was chosen for sampling. This location i' conservative as the actual release to the unr stricted environment is at :he discharge of the retention pond. The tritium sample at tic pond inlet point was 1.46 x 10 " pCi/mi, which indicated 2 dilution factor of 13 because of normal sewage discharge and

, " clean" floor drain dilution. Using this dilution factor, the calculated Iodine 131 concer.tration at this point was abcat 2.7 x 10 7 uCi/ml. The first actual I 131 sample at th s point was 2.34 x 10-7 pCi/ml. The analysis confirms thct none of the isotopes discharged to unrestricted creas ex-ceeded maximum permissible concentration as listed in 10CFR20, Appendix 3, Table II. To fully insurc that these values were not exceeded, a daily sample ..ac taken at the inlet to t':e re- .

tention pond. The daily samplou indicated a gradually decreas-ing radioactivity concentration, and by August 6 the concentra-tions at the retention pond in st had returned to backgrcund levels.

The indication in the control rocm for the Uni- 2 refueling water storage tank wan Cound to be improperly s.uli-brated. The level instrument shoala nave been calibracec in a range of 0 - 800 inches , bul- i.n actuality it was calibrated for a range of 0 - 1000 inches. "t - 09 4 1 inoication was correctly calibrated to the 0 - 800 D The control room :.evel instrumentation has been recalt v,:ai for the proper ranc;e..

The radioactive concentracions in tho retentica pond are continually b:'.ng diluted by normal plant sewage watar und by " clean" sump drainage. No radicactive release in excess of maximum permissible concentration has or will be made as a re-sult of this occurrence. gipq nld llt Ib

{

Verv truly 'r &<

d.bs ah u.u&

e e,..s.,mammi,m M. +w,- gem . .e . .*e-.. n- .m.. -w.in msi es ei ce. g