ML19341A230
| ML19341A230 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/14/1981 |
| From: | Elashry M TENNESSEE VALLEY AUTHORITY |
| To: | Warr J ALABAMA, STATE OF |
| References | |
| NUDOCS 8101220411 | |
| Download: ML19341A230 (3) | |
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TENNESSEE VALLEY AUTHORITY Noamis. TENNESSEE 37828 January 14, 1981 Mr. James W. Warr, Director Alabama Water Improvement Commission Public Health Service Building Montgomery, Alabama 36130
Dear Mr. Warr:
REQUEST FOR TEMPORARY RELIEF FROM THE 5 RESERVOIR TEMPERATUtE RISE LIMIT AT BROWNS FERRY NUCLEAR PLANT The extreme meteorological conditions which existed during the summer of 1980 resulted in record power demands on the TVA system. The prolonged hot weather and drought conditions contributed to reducing the water in storage in the hydro system much faster than normal during the summer months. Since then, water stored in TVA reservoirs has been conserved by reducing hydro generation, e.g.,
the average hydro generation for October through December was the lowest since 1954 with the month of December being the lowest since 1944. Dry weather has continued with rainfall in December being 1.2 inches compared to a normal 4.8 inches. Rainfall over the Tennessee Valley for December and the period of June through December was the second lowest of 91 years of record. Energy in storage for the hydro system is the lowest since 1968.
Cherokee, Douglas, and Norris Reservoirs are currently below their normal minimum elevations, and many of the other tributary storage reservoirs are approaching their normal minimum levels.
Should the dry weather persist, it will be necessary to continue to draw upstream reservoirs below normal minimum levels. TVA will try to maintain a river flow of approximately 18,000 cfs at Browns Ferry. However, there is inadequate water in storage to augment flow past Browns Ferry in order to meet the 5 F maximum allowable reservoir temperature rise criteria with all 3 units in operation. Thus far this winter, Browns Ferry unit 3 has been shut down for refueling and is expected to return to service on January 16.
With two units in operation on January 12, the reservoir temperature rise gradually increased and reached 4.6 F.
To prevent exceeding the 5 F rise, the flow by Browns Ferry was increased from 20,000 cfs to 26,000 cfs. However, this practice cannot be continued for 1cag periods of time due to the low water level of our reservoirs.
It is thus apparent that after unit 3 is in service, auxiliarv cooling or load reductions will be required to avoid exceeding the *" '. maximum reservoir criteria.
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. Mr. James W. Warr January 14, 1981 Problems will be encountered should either of these alternatives be implemented. Reduction in output at Browns Ferry could seriously impair the ability of TVA to meet winter peak power demands. For example, on Monday, January 12, the TVA peak demand was 21,246 MW with the weighted average temperature for TVA's major load centers of 9.2 F.
To meet this demand, TVA ran all available oil-fired combustion turbines and imported 740 MW from the neighboring systems on an economy and emergency return basis.
The startup and operation of the cooling towers when wet-bulb temperatures are subfreezing are hazardous due to the potential for icing and the possible collapse of the cooling towers. This ccndititon is particularly hazardous at Browns Ferry during tower startup because the supply water in the open channel to the cooling towers is initially very near freezing and could freeze during startup. TVA is currently in the process of installing a cooling tower bypass system to reduce the startup problem during freezing conditions; however, the system will not be completely operational this winter.
In addition, there is a high risk that temporary transmission lines in the cooling tower area would not be capable of supporting ice load.ags which could develop due to cooling tower plume interference during freezing conditions. These transmission lines provide vital offsite power for safe shutdown of the plant.
TVA has not encountered an extended period of low reservoir flows coin-cidental with potential freezing conditions since the cooling towers have been available. Operator training and operational experience during potential freezing conditions are therefore limited. We believe that starting and operating the cooling towers is extremely risky when icing conditicus exist, and this could greatly jeopardize the availability of the towers during the critical r.enGer months of 1981.
Studies at the TVA/ EPA Biothermal Research facility at Browns Ferry have shown no adverse effect of thermal increases of up to 16 F during the winter months. Observed effects of increased levels of thermal enrichment have appeared beneficial to aquatic biota during periods of very low ambient water temperatures. Temperatures are currently at these low levels in Wheeler Reservoir (upstream temperature 36 F on January 12, 1981). There is little chance of thermal shock from fish which are resident in Wheeler Reservoir for water temperature differentials of 8.5 F or less. Although documentation is unavailable, it appears that the risk of. impact to fishery resources from continuing to draw down the reservoirs is greater than the risk associated with operation at the proposed 8.5 F temperature rise limit.
We therefore request temporary relief from the 5 F thermal rise limit and request that a maximum reservoir temperature rise of 8.5 F be granted until April-1981.
At that time the potential for cooling tower freezing should be
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w Mr. Ja W. Warr January 14, 1981 decreased, and the plant thermal load will drop back to that coming from 2 units.
TVA presently is scheduled to remove unit 1 from service on April 4,1981, for a scheduled refueling and maintenance outage. We estimate that the 8.5 F allowable thermal rise will sustain 3-unit operation at Browns Ferry with the current minimum hydro releases for navigation.
Sincerely, Mohamed T. El-Ashry, Ph.D.
Director of Environmental Quality ec:
Mr. Charles Kaplan Enforcement Division U.S. Environmental Protection Agency Region IV 345 Courtland Street, NE Atlanta, Georgia 30308 p/ Director of Nuclear Reactor Regulation Attention:
Mr. Darrel G. Eisenhut, Director Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555 Identical letter sent to Mr. Howard D. Zeller, Acting Director, Enforcement Division, U.S. Environmental Protection Agency, Region IV, 345 Courtland Street, i
NE, Atlanta, Georgia 30308
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