ML20209E519

Documents Addl Info Provided to NRC in 870121 Telcon Re Delays in Completion of Testing & Balancing Activities,Leak Rate from Facility ECCS Equipment in Auxiliary Bldg & Performance of Addl Leak Rate Determinations

ML20209E519
Person / Time
Site:	Byron
Issue date:	01/27/1987
From:	Ainger K COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
2638K, NUDOCS 8702040664
Download: ML20209E519 (4)

Text

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i [ CORHROR M EcNaOR

( m~ j One First National Plaza, Chicago, Illinois

% j Address Reply t Post Omco Box 767 .

V Chica00. Illinois 60690 0767 January 27, 1987 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Byron Station Unit 2 Auxiliary Building Ventilation System NRC Docket No. 50-455 References (a): October 1, 1986 letter from D. L. Farrar to H. R. Denton (b): October 24, 1986 letter from S. C. Hunsader to H. R. Denton (c): January 13, 1987 letter from K. A. Ainger 4 to H. R. Denton 4

Dear Mr. Denton:

i Reference (c) transmitted a request for extension of schedular relief for completion of preoperational integrated testing of the auxiliary building ventilation system. In a telephone call with Mr. S. A. Varga and others of the NRC Staff on January 21, 1987, additional information was provided to support our request to extend the schedular relief. This letter documents the information provided to the NRC staff during the telephone call.

Delays in Completion of Testing and Balancing Activities l

prior to October 1, 1986, the ongoing activities of Unit 2 construction in the auxiliary building prevented performance of integrated testing and balancing on the auxiliary building ventilation system for Unit 2. Specifically, subcompartment doors were continually being opened as a result of personnel traffic and wall penetration seals were not yet complete. This affected air flows in the Unit 2 portions of the auxiliary building. In October of 1986, a complete set of air flow readings was taken to establish a baseline. From this baseline data, it was determined that additional dampers were necessary to provide control for fine tuning of air flows.

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8702040664 870127 PDR ADOCK 05000455 P PDR g

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Mr. H.-R. Denton January 27, 1987 In early November of 1986, an approximate one week delay was encountered in the installation of these dampers due to electrical noise spiking induced on the nuclear instrumentation source range channels. The electrical noise emanated from the welding process required for the damper installation. In late November, an approxi-mate three week delay was encountered due to discovery of very fine cracks in the auxiliary building exhaust fan discharge duct work.

The cracking has been attributed to air flow induced vibration.

During that three week period, fan combinations were shutdown to install internal tie-rods and external stiffeners to dampen the vibration. crack propagation has been arrested, however additional repairs and modifications are planned to be incorporated when sufficient time can be scheduled.

As the testing and balancing (TAB) activities progressed since November, additional delays of one to two days each were encountered on subtasks associated with the TAB effort. These delays resulted from modifications required on flow controls and repairs required on turning vanes, dampers, etc. However, these delays have not affected the overall effort to the same extent as the delays in November.

The manpower effort to support the activities discussed above was extensive. Beginning October 1, 1986 and continuing to late November, the TAB effort was performed on a two shift basis. The night shift worked at least a 10-hour shift five days per week and performed the air flow readings required for the baseline data. The day shift worked an 8-hour shift five days per week plus an

, intermittent sixth day when plant conditions allowed. The day shift

! performed the adjustment or repairs identified from the night shift data taking effort. For a three week period beginning in late

!' November and continuing to mid-December, the effort was performed on a two shift basis, with each shift working 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> six days per week. Since mid-December, the effort in the field has been performed on one 10-hour shift six days per week with the data analysis effort being performed by Sargent & Lundy on an after shift basis. Based on the foregoing, we believe every reasonable effort that could possibly be made has been expended towards achieving the originally projected completion date of July 1, 1987.

As a result of the delays encountered to date, we now project the TAB effort will not be completed until March 27, 1987 at the

earliest. Therefore, the preoperational testing, results review and approval will extend to August, 1987. However, based on our learning experience so far and overlap with the upcoming Unit I refueling outage, we believe additional unknown delays will be encountered. On i '

the basis of the foregoing, we have requested the schedular relief for completion of the preoperational integrated testing of the auxiliary building ventilation system be extended to October 1, 1987.

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.w Mr.-H. R. Denton January 27, 1987 Leak Rate From Unit 2 BCCS Equipment in the Auxiliary Building The formal quantitative leakage determination of Unit 2 BCCS equipment discussed in references (a) and-(b) has not been performed yet on Unit 2. However, we believe the Unit 2 equipment leakage will be similar or less than the leakage identified on Unit 1. The formal quantitative leakage determination performed on Unit 1 prior to exceeding 30% power identified a leak rate of 1.5 gallons per hour.

This leakage was subsequently reduced by the performance of maintenance activities. If a leakage measurement was performed today on Unit 1, we would expect the leak rate to be even less than 1.5 gallons per hour because of the extensive effort to minimize radioactive contamination levels in the plant.

The corresponding Unit 2 BCCS equipment is identical to that of Unit 1 and the Unit 2 design configuration is essentially identical to that of Unit 1. As a result of our experience with contamination control on Unit 1, Unit 2 underwent a more expansive program of refurbished valve packing prior to fuel load than was applied to Unit

1. Because of this effort, our operating staff walkdowns of the Unit 2 systems to date have confirmed that Unit 2 is more leak tight than Unit I was at the corresponding point of power ascension.

Performance of Additional Leak Rate Determinations As stated in references (a) and (b), a formal quantitative

! determination of Unit 2 ECCS equipment leakage in the auxiliary building will be performed prior to exceeding 30% power. Any unacceptable leakage subsequently identified by the operating staff i

during system walkdowns or performance of numerous technical i specification equipment operability surveillances will be subjected

to maintenance activities. Additionally, in light of our request for extension of schedular relief, two addit?onal formal quantitative leak rete determinations will be performed. The first leak rate

, determination will be performed in February, 1987 prior to exceeding 30% power. The next additional leakage rate determination will be l performed within the two week period of April 1 to April 15, 1987.

The following additional leakage rate determination will be performed within the two week period of July 1 to July 15, 1987. Should Unit 2 be in an outage condition within these periods, the leakage rate

determinations will be performed within the first two weeks after returning to power.

Mr. H. R. Denton January 27, 1987 Auxiliary Building Ventilation System Operating Condition The auxiliary building ventilation system is common to Units 1 and 2 and serves the auxiliary building and fuel handling building.

The system is designed to filter radioactive contaminants from the air exhausted from these buildings. As discussed in Attachment B of reference (a) and further expanded upon in Attachment A of reference (c), the Unit 2 portion of the auxiliary building ventilation system is constructed and supply and exhaust airflows are functioning.

Exhaust airflows are directed through the ventilation system filters per design. The supply and exhaust airflows are maintaining the Unit 2 areas at a negative pressure with respect to atmosphere. The remaining TAB activities are basically the adjustment of balancing demper positions to fine tune the air flows to each individual service branch.

We believe the information presented above provides additional justification and support for the extension of schedular relief being sought for completion of integrated preoperational testing of the auxiliary building ventilation system.

Please direct any questions regarding this matter to this office.

Very truly yours,

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K. A. Ainger Nuclear Licensing Administrator 1m cc: Byron Resident Inspector Regional Administrator - RIII 2638K