ML20198B532
| ML20198B532 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 12/12/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20198B530 | List: |
| References | |
| NUDOCS 9801060349 | |
| Download: ML20198B532 (3) | |
Text
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j<?Nk umiso states j-N NUCLEAR REGULATORY COMMISSION -
y WASHINGTON, D.C, SteeMGM f
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CONCERNING TECHNICAL SPECIFICATION BASES CHANGES REGARDING THE EMERGENCY DIESEL GENERATOR MR HANDLING SYSTEM FLORIDA POWER CORPORATION CRYSTAL RIVER UNIT 3 QOCKET No. 50-302
.1.0 JNTBf)DI)CTION By letter dated August 26,1997, Florida Power Corporation (FPC or the licensee) submitted
- License Amendment Request 216 (LAR-216) which proposed an amendment to Operating License No. DPR-72 for Crystal River Unit 3 (CR3) to change the design basis of the emergency diesel generator (EDG) air handling system. The proposed change to the design o
basis became necessary as a result of EDG upgrade modifications to increase the 200-hour and 2000-hour service ratings for each EDG, To reflect the change to the design basis, the Econsee has proposed revisions to Esctions 8.2.3 (Sources of Auxiliary Power) and g.7 (Plant Veretilation Systems) of the Final Safety Analysis Report (FSAR), and revisions to Bases Sections B 3.8.1 (AC Sources-Operating) and B 3.8.2 jAC Sources-Shutdown) of the CR3 Technical Specif, cations. The proposed changes identity that for EDG operability either one
- or two cooling fans must be operable depending upon the air inlet temperature.
2.0 EVALUATlON
- The EDG sir handling system provides continuous ventilation, and dissipates intemal heat
= gair:s in the EDG engine room and EDG control ronm (i.e., EDG rooms) when the diesel is operating.- The system safety function is to supply sufficient air to maintain the temperature of the EDG rooms equal to or less than 120 degrees fahrenheit (*F), the manufacturer's limit.
Each EDG is provided with two axial flow cooling fans. According to the original design requirements, two fut capacity cooling fans were provided for each EDG, but only one of the two was required to maintain the EDG room temperature eithin the manufacturer's limits.
Thus, the criginal design consisted of two 100 percent cupacity cooling fans that supplied air to the EDG rooms.
In 1g87, the licensee recognized that combustion air was being drawn directly from the _EDG angine room at unacceptably high temperatures. The temporary solution was to install F
additional duct work to discharge air from the cooling fans to the area of the EDG turbocharger inlet.. As a result, the cooling fans had to supply combustion air in addition to
- room cooling air, and the total system air flow increased above the capacity of one fan.
Therefore, two cooling fans were required to operate to support EDG operation. At that time, i
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the FSAR was revised to reflect that the fans were each 50 percent capacity and both were
" required for EDG operation.
i Ir* 1990, the licensee installed a permanent modification to provide a dedicated combustion air flow path to the turtscharger of ooch EDG with a cooler air source from outside the EDG engme room, That permar,ent solution restored the EDG mir handling system cooling fans to
. the original design margin requiring one of the two fans to supply air to the EDG roorm.
However, rithough plant documentation was updated, the FSAR was not updated to reflect that only one fan was required to support EDG operation. Therefore,' the current FSAR (Revision 23) incorrectly states that the EDG air handling system design basis requires both -
cooling fans.
I
. During the current extended outage, which began in 1G96, the licensee upgraded the capacity of the EDGs, The heat load in the EDG rooms will increase due to operating the EDGs at higher power levels. Accordingly, single fan or dual fan operation provides adequate cooling depending on the fan supply air temperature. Dual fan operation is required at fan supply temperatures equal to or greater than 85'F. The licensee's new l analysis showed that with both fans operating the EDG room temperatures will not exceed the design temperature of 120*F. Currently, both EDG air handling system cooling fans start automatically when the associated EDG starts.
The licensee's proposed changes to the design basis of the EDG air handling system results -
l in a slight increase in the probability of inademete EDG room cooling since the air handling syste.n cooling fans will now be susceptible to a single failure et higher temperatures since two fans are required above 85*F. This was the licensee's basis for concluding that an unroviewed safety question existed. However, the air handling system has always been susceptible to some single failures since the system includes a single roughing filter and a common power supply to the fans. The staff has no requirements for redundant air handling systems for individual EDGs. Redundancy to meet the requirements of General Design Criterion (GDC) 17 " Electric Power Systems," is provided by the redundant EDGs and their associated supporting systems, including ventilation systems. Accordingly, a single 100 percent capacity cooling fan would be acceptable (and has been found acceptable at other plants) to meet the design basis for EDG ventilation cooling. However, the dual fan design at CR3 provides greater than minimal protection, if the EDG air supply temperature is less than 85'F and one fan fails, the system could maintain EDG room cooling within the design limits with the remaining fan, in the event the air sapply temperature exceeds 85'F and one fan fails, the remaining fan may a!!ow the temperature to rise above the design limit but should i
not result in immediate EDG failure, although the life of some electrical _ equipment may be shortened, i
f3.0- STATE CONSULTATION Based upon written notice of the proposed amendment, the Florida State official had no comments.
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4.0 ENVIRONMENTAL CONSIDERATION
S The amendment changes requirements with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any emuents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such finding (62 FR 50004). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the -
issuance of the amendment.
5.0 CONCLUSION
Based on its evaluation, the staff concludes that the change to the design basis requiring single or dual cooling fan operation, depending on fan supply air temperature, for EDG operability is in accordance with the sirigle failure requirwments of GDC 17 and is consistent with the single failure protection capabihty afforded by other EDG support systems, i.e., a single failure cannot affect both EDGs. The staff, therefore, concludes that the licensee's proposed changes to FSAR and Bases sections of the plant technical specifications are acceptable.
Principal Contributor. W. LeFave Date: December 12, 1997 m -
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