ML19317D468

Ro:On 730423,water Spill from Refueling Water Storage Tank to Storm Drainage Sys.Caused by Inadequate Procedures & Personnel Error.Plant Mgt Will Review Methods & Have Cautioned Operators to Exercise Extreme Caution

ML19317D468
Person / Time
Site:	Oconee, Robinson
Issue date:	05/01/1973
From:	Utley E CAROLINA POWER & LIGHT CO.
To:
Shared Package
ML19317D464	List: ML19317D466 ML19317D468
References
NUDOCS 7912030369
Download: ML19317D468 (4)

Text

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. ) . .a ~ . ., L 3 Carolina Power & tight Company y May 1, 1973 e ,x

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Mr. John F. O' Leary - '

Directorate of Reactor Licensins MAY 7 1973 s-U. S. At6mic Energy Con:nission E g gi. mg .,

Washington, D. C. 20545 cwa:s wxsur 50-261 g rui:ca

Dear Mr. O' Leary:

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H. B. ROBINSON UNIT NO. 2 LICENSE DPR-23 REFUELING WATER STORAGE TANK SPILL TO THE PLLNT DRAINAGE SYSTEM In accordance uith paragraph 6.6.2.D, Technical Specifications, it is reported that on April 23, 1973, with the reactor in a refueling shutdoms condition, a spill of water from the Refueling Water Storage Tank (RUST) to the plant storm drainage system occurred.

Following core reload, the louer icvcis of the containment refueling cavity were being drained to the Reactor Coolant Drain Tank and then pumped to the RWST. At approximately 1530, the icvel in the RWST as indicated on the RTCB vas 987.. The cavity was being drained at approximat:cly 35 gpm. Draining cnntinued until, at 2300, it was dis-covered that the RWST uas overflowing to the plant drainage system. The cavity draining was immediately stopped, and transfer of the water from the RWST to the Spent Fuci Pit was begun. Overflow of the RNST imrediately diminit:hed, and by 0013, April 24, all flow to the storm drainage system ,

had ceased.

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It is estimated that the RNST filled to overflow 1cvel at 1845.

Assuming' that all water pumped irem this time until the pump was stopped  !

floucd to the drain, this would amount to approximately 8,925 gallons. l The water uhich was released flowed to the storm drain and subsequently into Black Crcck belou the Robinson impoundment dam.

A sampic was collected from the PNST and analyzed by gamma spectrometry for total activity and isotopic identification. Since the water was released from the 3NST overflou line, the activity in this sample is idcutical to that uhich was relcased. Concentrations of specific radionuclides from this sampic are shcun in the attached table. Based on the total release of 8,925 gallons of water, 379.29 millicuries of radio-activity, excluding tritium, were relcased to the drainage ditch and subsequently to Black Crcck. At the time of the release there was a flow

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Mr. O', Leary May 1, 1973 of 680 gpm in the drainage ditch and a flow of 260 CFS in Black Creek resulting in coi.centrations in these streams averaged over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as shown in the cabic.

This release resulted in a concentration, averaged over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, of 1807. of MPC values shown in 10CFR20 in the drainage ditch and 17. of these values in Black Creek. Due to the dilution flow in Black Creek at the time of the release no adverse environmental effects vould result. An automatic water sampler was in operation on Black Creek downstream of where the drainage ditch enters during the entire period of the release.

Gross beta and gamma spectrum analyses of this sampic showed no detectable radioactivity which verifics that no adverse environmental effects would result from the release.

Since Technical Specification limits for liquid discharge are based on equilibrium values of radionuclides which are released to the lake, a comparison of this release (to the stream belou the impoundment) to those limits han no meaning. This release does represent, houcver, 77.5% of the total liquid activity released to the environment during 1973. j This incident is not reportabic under 10CFR20 because the 24-hour average concentration in the drainage ditch did not eneced 10 tir.cs the MPC values and because the 8-hour average (reference Tech. Spec. Section 3.9.1.2) did not execed 10 times the permitted values of Technical l Specifications and Basos. I To prevent recurrence of this incident, the following corrective measures have been or will be initiated:

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1. Plant management will revicu methods to prevent recurrence - j of these type incidents.

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2. All operators have been cautioned to exercise extreme I caution when transferring radioactive liquids.

3. Normal water level in the Refueling Water Storage Tank will be maintained at 927. instead of the previous level of 987..

4. A high 1cyc1 nlarm will be installed to annunciate on the RTGB should the refueling water storage tank icyc1 reach 957..

5. A modification to route the overflou from the RNST to the plant liquid waste system has been under investigation and will be pursued further.

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i Mr,, O'Ictry r May 1, 1973 The Plant Nucicar Safety Comittee reviewed this incident on .

April 24, 1973, and it was reported to Mr. !!crb Whitener of DRO by telephone and to Mr. Norman C. Mosely of the same office by telegraph on the same date. The South Caroline State Board of Health has also been informed of the incident.

Very truly yours, E. E. Uticy (. 6 Vice-President Bulk Power Supply DBW/za Attachment cc: Mr. C. D. Barham

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Rk'ST CONCENTRATION -

CONCENTRATION .

/ SAMPLE S(PC IN IN MILLICURIES .

ISOTOPE ANAI.YSIS 10 CFR 20 DRAINAGE DITCH MPCF BLACK CREEK ( } MPCF RELEASED ( }

2.02 x 10 ~7 ~9

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l Co-57 2.23 x 10 4 x 10 0.0005 0.75 1.18 x 10 . 000003 1.25 x 10 -5

~3 Cr-51 1.37 x 10~ 2 x 10 0.00625 7.28 x 10 -8 .000036 46.28 .g Co-58 6.09 x 10~ 9 x 10~ 6.09 x 10~ 0.677 3.55 x 10~ .003944 255.99 I Cs-134 2.96 x 10~ -6 ~0 ~0 9 x 10 2.71 x 10 0.301 1.58 x 10 .001756 10.07

~0 C3-137 3.53 x 10~ 2 x 10~ 3.21 x 10 0.1605 1.87 x 10~ .000935 11.92 Mb-95 1.03 x 10 1 x 10 9.38 x 10~ 0.0094 5.47 x 10 ~9 .000055 3.48 "a-54 ~0 3.82 x 10~ 1 x 10 3.48 x 10 0.0348 2.03 x 10~ .000203 12.90 Co-60 2.01 x 10~ 3 x 10~ 1.83 x 10~ 0.610 1.07 x 10~ .00356 67.90 TOTALS 1.804 .0105 379.29

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(1) Based on a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average.and a flow in the ditch of 680 gpa $, g if Yki

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! (2) Based on a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> average and a flow in Black Creek of 260 ft 3/sec

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(3) Based on a release of 8925 gallons. g j

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