ML20247R360

Forwards Response to Re Deficiencies Noted in Performance Audit Insp Conducted on 890329-31.Corrective Actions:Listed Activities Conducted or Scheduled to Improve Diffuser Flow Measurement,Calibr & Recordkeeping

ML20247R360
Person / Time
Site:	Sequoyah
Issue date:	06/02/1989
From:	Schmierbach M TENNESSEE VALLEY AUTHORITY
To:	Stewart P TENNESSEE, STATE OF
References
NUDOCS 8906070213
Download: ML20247R360 (6)

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, , a TENN EZ2EE VALLEY . AUTHORITY KNOXVILLE. TENNESSEE 379o2 JUNGE$89 1 Mr. Philip L. Stewart, Manager Chattanooga Field Office

! Tennessee Division of Water Pollution control

2501 Milne Avenue Chattanooga, Tennessee 37406-3399

Dear Mr. Stewart:

. TENNESSEE VALLEY AUTHORITY - SEQUOYAH NUCLEAR PLANT (SQN) - NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES) PERMIT NO. TN0026450 - RESPONSE TO PERFORMANCE AUDIT INSPECTION (PAI)

This in response to your. April 21 letter transmitting the results of the PAI conducted at SQN on March 29-31. A response to the deficiencies listed in

~ item 1 and an update to the situation listed in item 3 of your letter are enclosed.

If you or your staff have any questions or comments regarding this information, please contact Abraham H. Loudermilk, Jr., at (615) 632-6656 in Knoxville ^.

Sincerely.

A. tA W M. Paul Schmierbach, Manager Environmental Quality Encicsure cc (Enclosure):

Mr. Bruce R. Barrett, Director Water Management Division United States Environmental Protection Agency, Region IV 345 Courtland Street, NE.

Atlanta, Georgia 30365 Ms.~S. C. Black, Assistant Director for Projects TVA Projects Division United States Nuclear Regulatory Commission One White Flint, North l 11555 Rockville Pike I Rockville, Maryland 20852 8906070213 890602 PDR ADOCK 05000327 Q PDC l-An Equal Opportunity Employer k_ ' __ - _

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j .- -- 2 . {

Mr. Philip L. Stewart.

J'?! 0 21989 l

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, Mr. F..R. McCoy, Ass 3 Director l

.for Inspection Pr' ,  !

TVA Projects Divi' ,

~ United States Nu *stulatory Commission Region JJ i 101 Medatta Stt , NW. i

. Suite 2900 Atlanta, Georgia 30323 ,

I Sequoyah Resident Inspector l Sequoyah Nuclear Plant  !

2600 Igou Ferry Road l Soddy Daisy, Tennessee. 37379 l Mr. Garland P. Wiggins, Manager 1 Industrial Facilities Section ]

Division of Water Pollution Control '

I Tennessee Department of Health and Environment j TERRA Building l 150 Ninth Avenue, North i Nashville, Tennessee 37219-5404 , j U.S. Nuclear Regulatory Commission Attention: Document Control Desk  !

Washington, D.C. 20555 )

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ENCLOSURE RESPONSE TO APRIL 21 PERFORMANCE AUD1'1 INSPECTION REPORT FOR SEQUOYAH NUCLEAR PLANT

1. Response to the deficiencies listed in item 1 A detailed explanation of the diffuser flow measurement and calibration methods was presented in my June 29, 1988 letter to you; therefore, these will not be repeated here. However, concern was expressed over the validity of the diffuser flow calibration equation during reservoir summer pool conditions, since it was developed under Chickamauga Reservoir winter pool elevations. The commonly accepted hydraulic theory which was used to develop the flow equation states that flow in a diffuser is related to the difference in pressure at the two ends of the diffuser. The significant parameter here is the difference in pressure (i.e., difference in reservoir and pond elevations) and not the absolute pressure (i.e. , reservoir or pond elevations alone). At high summer reservoir pool level, the water level in the diffuser pond is also high. Under identical plant operation, summer reservoir pool gives the same pressure (or water level) difference as that during low winter reservoir pool where the diffuser pond is also low. This is illustrated in the enclosed figure. The theory may be further illustrated by considering what happens during no plant flow (i.e. , no warm water discharge). The diffuser pond level would be the same as the reservoir level. As the reservoir level changes, a temporary pressure difference is created which esuses momentary flow into the diffuser until the pond and reservoir levels are the same. This condition holds regardless of the summer or winter reservoir levels. The additional pressure (or pond water level) difference caused by plant flow is simply superimposed on the static condition and is the same during sunmer or winter time.

The equation used to calculate the flow was developed based on four data points collected in 1986 and reported in my June 29, 1989 letter to you.

To improve the diffuser flow measurement, calibration, and recordkeeping, the following activities have been conducted or are scheduled for the remainder of this calendar year.

A. Field data (velocity measurements, etc.) were collected on March 29, 1989, during 1-unit operation.

B. Field data were collected on May 19, 1989, during 2-unit operation.

C. The equation used to calculate the flow will be updated by July 10 to incorporate the data collected i? March and May. This should provide a more accurate equation.

D. Field data will be colJected in July or August during 2-unit operation to verify the accuracy of the updated equation.

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E. Field data will be collected when one unit is shut down'or is operated at substantially reduced load such that the diffuser flow is different from 2-unit operation. This survey will be performed during the refueling outage scheduled in October if not before then. These results will be used to verify the accuracy of the flow equation at 1-unit flows.

F. A decision about updating the flow equation to include the July-August and October data will be made after these data become available.

G. The results of all field surveys will be documented and copies maintained at the Environmental Data Station and in the Site Environmental Manager's office at SQN.

H. As discussed with Mrs. Ann McGregor during the inspection, the accuracy of the existing measuring point for verification of the bubble gage reading is being evaluated. During the inspection it appeared that the existing measuring point was within the draw-down zone of the diffuser intakes. The existing measuring poir,t for verification of the bubble gage reading was originally establitned outside the drawdown zone of the diffuser intakes, and was believed to be hydraulically acceptable.

A new water level measurement point outside the drawdown zone will be established in the diffuser pond by June 30. Weekly data will be collected at both the old and new locations for approximately two months. The results will be compared and documented. A permanent measuring point for the periodic verification of the bubble gauge data will then be established.

The orifice of the bubble gages are located outside the zone of influence of the diffuser draw-down. Therefore, the orifice will not be relocated unless the data from the 2-water level measurement points indicates a need to move it.

2. Update to the situation listed in item 3 Remedial action toward (PCB) cleanup in the low volume waste treatment pond (LVWTP) is continuing in an environmentally acceptable manner. We have and will continue to coordinate each phase of this effort with your office.

The Environmental Protection Agency and the Nuclear Regulatory Commission will be coordinated with as appropriate.

A letter was sent to Ann McGregor on April 27 that updated our efforts through March 27. Dewatering of the pond continued in April in accordance with our December 22, 1988 and and April 27, 1988 letters. However, we are approaching a point where dewatering of the pond by discharging in accordance with these letters is not practical. The PCB concentration has increased to a level that limits the discharge rate such that the pond cannot be dewatered fast enough to keep pace with rainfall accumulation.

Therefore, we are investigating alternatives for disposal of the remaining water in the pond (approximately 500,000 gallons). In the meantime, we will continue to discharge in accordance with the existing agreements.

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1 We are continuing to install plastic sheeting on the exposed parts of the LVWTP as the liquid level drops and the sediment dries sufficiently to support the laborers. This will reduce the opportunity for rainwater seosion to resuspend the PCB in the pond sediments thereby minimizing the PCB concentration in the discharge.

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$ 3.. FIGURE:

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SQN 1988 I. . 700 i i i i i i i i .. , i i

695 - --- POND ELEVATIDN ._

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690. - -

.p 685 ,a . j. g ., . . . . . . . . . . . . . t.. . .. .. . U .., ,,

680 -

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675 -

670 - -

665 -

660 .

3000 i i i i i i i i i i i i 1 DIFFUSER FLOW i 2500 -

2000 -

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u. 1500 - l 1000 I- ,

k .

500 -

t I t -t t t 1 i I I t .J g s..

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1800 i i- i_ i i i i i i i i. i 1600 - PLANT LOAD -

1400 -

1200 -

ID 1000 - ,

'3 '

l r 800 - 4 I~"

600 -

I 400 -

A 200 . ENG LAB 85/23/89 0 i' 0 30 60 90 120 150 180 210 240 270 300 330 360 DAY 1

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