ML20006B395

Updates Actions Implemented & Results Achieved from Plan Submitted in Jan 1988 for Reducing Temp in Reactor Bldg.Addl Temp Instrumentation Utilized & Installed Temporarily to Collect Data for Comparison of Temps

ML20006B395
Person / Time
Site:	Arkansas Nuclear
Issue date:	01/25/1990
From:	James Fisicaro ARKANSAS POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1CAN019016, 1CAN19016, NUDOCS 9002020037
Download: ML20006B395 (3)

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( Arkanset Power & UgM Company

&nansn5 Nsdeat Cho "LS' Rue 3. Box 137 G Russenene, tsR 4801 Tel 5D1 %4 31(O January 25, 1990 ICAN619016 U. S._ Nuclear Regulatory Commission Document Control Desk Mail Station P1-137 Wathington, DC 20555

Subject:

Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51 Arkansas Nuclear One, Unit 1 (ANO-1).

Reactor Building Temperature Action Plar; Update Gentlemen:

In ,lanuary 1988, the Arkaasas Power and Light Company (AP&L) submitted our planned, long term actions for improving the temperature in the Arkansas Nuclear One, Unit 1 (ANO-1) reactor building. That correspondence (ICAN018803) identified activities which haa either been taken or would be taken to reduce the temperature in thc ANO-1 reactor building during power operation. Those outlined actions were projected through the ninth refueling outage on ANO-1, (IR9) which currently is scheduled for the Fall, 1990. This submittal will update the previously submitted action plan by discussing what actions have been implemented and the results achieved to date.

Following the submittal of our January 1988 action plan, AP&L utilized additional temperature instrumentation, installed temporarily during the late 1987 ANO-1 mid-cycle outage, to collect additional data for comparison with temperatures predicted by the mathematical model developed in response to the temperature issue. During that same outage, AP&L also took steps to clean the reactor building cooling coils and air grills.. The'486' elevation temperature recorded the following summer was 158'F on August 11, 1988. The model prediction for those conditions was 156*F. The 486' elevation measurement point is in the vicinity of the polar crane and was chosen originally due to its representation of the return air temperature.

Prior to the summer of 1988. AP&L had revised station procedure-1015.03A

" Unit One Operations Logs", Revision 8, to provide guidance for two (2) l chiller operation as needed for cooling within the ANO-1 reactor building. I 9002020037 900125 PDR P ADOCK 05000313 D' [

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l U.*S. NRC 1 Page 2 l January 25, 1990 l l

1 During the eighth refueling outage on ANO-1 (IR8), which began in late 1988,  ;

AP&L replaced the two chilled water pumps with higher capacity pumps to 1 increase chilled water flow. The heating, ventilation and air conditioning (HVAC) system was cleaned and re-balanced to maximize air flow, as well as improve performance. Additionally, during this outage, select RCS insulation was repaired which had been noted during the previous mid-cycle  ;

outage walkdowns as deficient. Finally, the additional temperature monitors '

in the return air duct, which were installed temporarily during the mid-cycle outage, were supplemented with permanent installations.

The effectiveness of the IR8 modifications was evaluated during the summer '

of 1989 with the results indicating a decrease in the 486' elevation air temperature under similar meteorological conditions of 9'F (149'F as compared to 158'F in August 1988). The bulk average temperature, in comparison, is approximately 17'F lower than the 486' elevation temperature-(132*F). During the August 1987 JC0 efforts, we did not have methodology in place to calculate bulk-average temperature, therefore we cannot compare this latest value to one of 1987 vintage.

The mathematical model predicted a 1989 summer temperature at the 486' elevation of 143*F. Refinements to the mathematical model were implemented to reduce the variation between predictions and observations. The major adjustments made to the model, since the initial Project Scoping Report, were four-fold and consisted of revision of the overall heat transfer coefficient (U) for reactor coolant system (RCS) insulation, utilization of vendor and operating data to more accurately model chilled water coil-performance, better modeling of the solar radiation heat load and the utilization of a more representative coil inlet air temperature. These refinements resulted in temperatures predicted by the model to be much more representative of the actual temperature.

The revised model is being utilized to evaluate the most effective modifications to be implemented during 1R9 to further reduce the 4868 elevation temperature and, resultingly, the bulk average temperature. In that regard, AP&L intends to add an additional air-cooled chiller to the chilled water system to increase the chilled water system reliability and an additional air handling unit which will utilize the reactor building purge system duct to increase the capacity for heat removal from the building.

• The revised mathematical model predicts that these modifications should reduce the air temperature at the 486' elevation from the 149*F value e observed in August, 1989 to somewhere between 120 - 130'F. These values would be representative of bulk-average temperatures of from 105* - 115'F.

The IR9 modifications which are planned have a high probability of attaining our post 1R9 goal of a 486' elevation air temperature of 120-125*F, as discussed in the previous action plan. ,

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• U.'S, NRC Page 3 January 25, 1990 Additional actions, beyond 1R9, will depend upon the actual results achieved following the installation of these modifications discussed above. Such actions, if deemed appropriate, could include further repair / replacement of RCS insulation. The effects of the planned IR9 modifications will need to be evaluated and compared to the program goals before definitive post IR9 activities will be known.

AP&L believes that substantial improvement has been made to the ANO-1 reactor building temperature. Further reduction in the reactor building temperature is anticipated following the IR9 modifications discussed above.

Should you have any questions regarding this matter, do not hesitate to contact my office.

Very truly yours,

/

m '.)tu n ames Fisicaro Manage . Licensing I

JJF/1w l Attachments cc: Mr. Robert Martin U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011 NRC Senior Resident Inspector  !

Arkansas Nuclear One - ANO-1 & 2 Number 1, Nuclear Plant Road Russellville, AR 72801 I Mr. Thomas W. Alexion NRR Project Manager, Region IV/ANO-1 U. S. Nuclear Regulatory Commission NRR Mail Stop 13-D-18 One White Flint North 11555 Rockville Pike Rockville, Maryland 20852 Mr. Chester Poslusny NRR Project Manager, Region IV/ANO-2 U. S. Nuclear Regulatory Commission NRR Mail Stop 13-D-18 One White Flint North 11555 Rockville Pike Rockville, Maryland 20852