ML20085D224

Ro:On 730410,spill of Water from Refueling Water Storage Tank to Plant Storm Drainage Sys Occurred.Caused by Leakage in Line Between Spent Fuel Cooling Sys & Safety Injection Sys Due to High Pressure.Piping & Valves Pressurized

ML20085D224
Person / Time
Site:	Robinson
Issue date:	04/24/1973
From:	Utley E CAROLINA POWER & LIGHT CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085D211	List: ML20085D214 ML20085D224 ML20085D226
References
NUDOCS 8307210074
Download: ML20085D224 (2)

Text

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y E 50-261 b la h a Carolina Power & Light Company April 24, 1973 x

h Mr. John F. O' Leary Directorate of Reactor Licensing O AE.93 ia United States Atomic Energy Co:tr.ission Washington, D. C. 20545 e

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Dear Mr. O' Leary:

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N/r(c H. B. ROBINSON UNIT NO. 2 LICENSE DPR-23 SPILL TO THE PLANT DRAINAGE SYSTEM In accordance with paragraph 6.6.2.d, Technical Specifications, p it is reported that on April 10, 1973, with the reactor in a refueling

- shutdown condition, a spill of water from the Refueling Unter Storage Tank (RUST) to the plant storm drainage system occurred.

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At approximately 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br />, while performing Periodic Test Qf No. 2.2 (Safety Injection System Component Test), the icveln in the auxiliary 4 building and the refueling building sump tanks vere noted to be increasing jU faster than normal. At the same time, water waa observed seeping out of the room which houses the spent fuel pit heat exchanger and filters. Sinec hg one safety injection pump was rt.nning, this was suspected to be the source of the leakage. The pump was immediately secured and the leakage stopped.

t It was determined, by visual observation, that a portion of line between the spent fuel cooling system and the safety injection. system, had been p;g _

subjected to above normal pressures # causing leakage to_ occur through one vent ialve^and'around the body to bonnet flange on another valve. These

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valves were both diaphragm type valves and, when overpressured, will tend (d to compress the rubber diaphragm and gasket and leak with no subsequent valve damage. The isolation valve which isolates this system from the Of7 safety injection system was closca until a flange coula be installea, the area decontaminated, and the SI test completed with no other leakage experienced.

All piping and valves which were subjected to the overpressure have been pressurized to 160 PSIC and no leaks observed. In addition, a tag has been fabricated and attached to the spectacle flange located at Valve SI-896C with the following instructions: ,

"Before removing this flange, insure that the SI pumps are under administrative control of the Shift Foreman."

The water which was released flowed to the storm drain and subsequently into Black Creek below the_. lak,c, dam. This release resulted in the discharge of 3co~ gal ~lons of water which contained 23.5 mci of gross particulate and 19.5 mci of tritiuri~ activity. Over 95 percent of the 8307210074 730515 ,

CDPY SENT REGIO 14 .

PDR ADOCK 05000261 PDR S uo rayettevole street . P. O Box 1551 Raleigh, N. C. 27602 ,,J.L'[ p f

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O O so -2 n Mr. Joha F. O' Leary April 24, 1973 activity was identified as Coba_lt-58_(9.37 x 10-3 microcuries/ml) and Cobalt-60 (3.09 x 10-3 microcuries/ml) . Based on the measured flow in the storm drainage ditch (680 GPM) and in Black Creek (1.18 x 10+5 cpg),

average annual concentrations due to this release are:

. Drainage Ditch: CO-58 1.31 x 10-8 microcuries/ml CO-60 4.33 x 10-9 microcuries/ml Black Crcok: Co-58 7.53 x 10-11 microcuries/ml C0-60 2.49 x 10-11 microcuries/n1 These concentrations are well below the 10 CFR 20 limits of:

CO-58 S x 10-5 microcuries/ml C0-60 3 x 10-5 microcuries/ml The total activity release was 0.26% of the cumulative yearly technical specification limit for radionuclides excluding tritium and 5.1 x 10-4 percent of the yearly limit for tritium.

The Plant Nuclear Safety Committee reviewed this incident in regular session on April 11, 1973, and it was reported to Mr. Herb Whitener of DRO in person and to Mr. Norman C. Moseley of DRO by telegraph on the same date.

Very truly ours, f .

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E. E. Utley Vice-President (

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