ML20057A342
| ML20057A342 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 09/01/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20057A341 | List: |
| References | |
| NUDOCS 9309140040 | |
| Download: ML20057A342 (4) | |
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NUCLEAR REGULATORY COMMISSION (v j#
wissiscTen, o c. zoss+xn SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.177 TO FACILITY OPERATING LICENSE NO. DPR-50 METROPOLITAN EDISON COMPANY JERSEY CENTRAL POWER & LIGHT COMPANY PENNSYLVANIA ELECTRIC COMPANY GPU NUCLEAR CORPORATION THREE MILE ISLAND NUCLEAR STATION. UNIT NO. 1 DOCKET NO. 50-289
1.0 INTRODUCTION
By letter dated April 12, 1993, the GPU Nuclear Corporation (GPUN/ licensee) submitted a request for changes to the Three Mile Island Nuclear Station, Unit No.1 (THI-1) Technical Specifications (TS). The amendment request proposes to reduce the Technical Specification Section 3.15.3 minimua flow limit for the Auxiliary and Fuel Handling Building (FHB) ventilation system from 118,810 cubic feet per minute (cfm) to 100,580 cfm. The amendment would also remove the reference to flow recorder FR-151, one of three instruments that measures flow in the system, from the TS. The Auxiliary and FHB ventilation system is operated continuously to maintain a negative pressure inside the two buildings with respect to atmospheric pressure.
2.0 EVALUATION The FHB ventilation system is designed to maintain a minimum temperature of 60 F, and the supply and exhaust duct systems are arranged to direct the air flow to areas of progressively greater potential radioactivity. The air flow exhausts through a roughing, High Efficiency Particulate Absolute (HEPA), and charcoal adsorber filter system. The system is also designed to maintain a negative pressure in the building with respect to atmospheric to preclude the unmonitored release of radioactive material to the environment.
During fuel handling operations the Fuel Handling Building Engineered Safety Feature Ventilation System (FHBESFVS) is also placed in operation. The FHBESFVS is designed to mitigate, monitor and record the radiation release resulting from a postulated TMI-l fuel handling accident.
One minor typographical error was noted in the licensee's submittal and was corrected.
Item 6.b on TS page 3-104 incorrectly listed Action No. 29 and should have been Action No. 31.
The licensee has performed an engineering analysis to evaluate the effect of the proposed TS low limit of 100,580 CFM on the design basis of the FHB ventilation system.
In addition, the analysis considered any impact on the accuracy of the radiation monitors associated with the ventilation system. A summary of that analysis is presented below.
9309140040 930902 PDR ADOCK 05000289 P
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Neoative Pressure The FHB Unit 2 operating floor has its own ventilation system which is 1
operated in conjunction with the FHB ventilation system to maintain a combined negative pressure in both operating floors. A modification is planned to combine the two operating floors with only Unit 1 FHB ventilation system
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operating and maintaining negative pressure. When the modification is i
completed the resulting reduced exhaust flow of 27,320 CFM from FHB and actual supply air of 22,330 CFM to the FHB, will allow an infiltration of 4990 CFM to both operating floors. This infiltration air of 4990 CFM is adequate to maintain a negative pressure in both operating floors as demonstrated by recent testing with only the Unit 1 FHB ventilation system operating.
l The engineering analysis indicates that at the proposed TS-low limit, the resulting exhaust from the Auxiliary Building would be 54,110 CFM.
In order to maintain negative pressure, the obtainable supply air should be reduced i
below the exhaust flow. The reduction is performed automatically by the Static Pressure Controller (SPC-11) which controls the supply damper AH-D-3 to l
maintain the Auxiliary Building under a negative pressure at all times.
Recent test results, extrapolated to the proposed low TS limit, demonstrate the ability to maintain negative pressure.
i Heat Removal During normal operations, the only source of heat in the FHB is the water in the spent fuel pool that is heated by spent fuel rods. Operation of the FHB l
ventilation system at the proposed TS low limit of 100,580 CFM would result in a lower evaporation rate because the air movement across the fuel pool.would be reduced. The water in the fuel pool is cooled by a redundant cooling pump and heat exchange system and is not dependent on evaporation. Therefore,-the proposed TS low limit does not adversely affect the cooling process of the i
spent fuel pool.
l Because of the reduced exhaust flow, the temperature in various areas of the j
Auxiliary Building is expected to rise by no more than 3 F on the basis of i
previous temperature rise testing at TMI-1. A loss of ventilation test was j
j performed in 1987 for the Nuclear Service Closed Cooling Water (NSCCW) Pump i
l room. With three pumps running during the test, the maximum temperature l
obtained after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> without ventilation was 99"F. Since the balance of i
the Auxiliary Building does not have a dilar concentration of equipment,-the i
temperature should not rise above 99'F.
A 3*F increase in that value will '
l maintain the building temperature at a value below the 104*F maximum indicated l
in the Final Safety Analysis Report (FSAR). The increase in temperature will not affect nuclear safety related areas which are provided with independent redundant recirculating cooling units that maintain the temperature within equipment qualification limits._ During winter the areas are heated by separate unit heaters on a zone basis to maintair. at least:60 F.
l The efficiency of the exhaust filtration units will not be adversely affected-by this change. The charcoal filters utilize the principles 'of adsorption.
In the adsorption process the longer the residence time, the more adsorption of iodine occurs. Therefore, reducing the exhaust flow rate will not decrease filtration efficiency.
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. The function of Radiation Monitors RM-A4 and RM-A6 is to isolate the FHB and the Auxiliary building, respectively, in the event of a hi1h alarm on either radiation monitor. As part of. this process an alarm is annunciated in the l
Control Room and the supply fans are automatically shut down. These monitors, which are located before the HEPA and charcoal filters, are installed to provide representative effluent samples of each waste stream. They are provided with isokinetic nozzles. The engineering analysis indicates.that, at the proposed lower TS flow, the conditions will be such that insignificant error in sampling will occer. Therefore, the function of these radiation monitors will not be adversely affected by the proposed change.
RM-A8, which j
is located after the filters, will not be adversely affected for the same i
reasons.
l Prior to the novement of fuel in the FHB, the FHB ESF filtration unit is started and run in parallel with the Auxiliary and FHB ventilation system.
In the event of a fuel handling accident, RM-G9, located on the fuel handling bridge, and RM-A4 will automatically isolate the FHB operating floor, i
annunciate an alarm in the Control Room and shut down the ' supply fan. The reduced exhaust flow will not affect the safety operation of the ESF filtration unit during a fuel handling accident in the FHB.
i In a separate, but related, change, references to FR-151 are to be deleted from two TS tables.
Despite several attempts to improve its accuracy, air i
flow measurements taken during recalibration and relocation show sustained but inconsistent errors. The location of the probe for FR-151 is at the wye duct l
section where the two discharge air flows from fans AH-E-14A (or C) and AH-E-148 (or D) meet.
Relocating FR-151 was considered but rejected as not cost effective. The change involves removing the cited references to FR-151 as an instrument used to measure flow.
FR-151 will not be physically disabled nor removed from the duct. Therefore, the proposed change does not impact the plant design or configuration.
As indicated in TS Table 3.21-2, a minimum of one operable channel for the Auxiliary and FHB ventilation exhaust system (either FR-151-or FR-149 and FR-i 150) is required to be available at all times. With the proposed change, FR-149 and FR-150 will be the primary devices used to measure the flow rate of the Auxiliary and FHB exhaust ventilation system.
In the event either FR-149 l
or FR-150 is out of service, FR-151 may be used to estimate the total exhaust flow by comparing the FR-151 strip chart before and after the failure.
If s
after the failure, the FR-151 trace is not flat and steady and indicates that there is significant change, then other means of estimating the total exhaust i
flow will be utilized based on a Technical Specification action statement.
With the availability of other methods to estimate the flow rate, the proposed change will not reduce the margin of safety as defined in the SAR and in the basis of the TS.
In addition, the use of FR-149 and FR-150 without a TS redundant channel is consistent with other TMI-l effluent monitors and previous Standard Technical Specifications.
The NRC staff has reviewed this request and its justification and concludes it i
is acceptable.
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3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Pennsylvania State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
l The amendment changes a requirement with respect to installation or use of a l
facility component located within the restricted area as defined in 10 CFR l
Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no i
significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the l
amendment involves no significant hazards consideratici, and there has been no public comment on such finding (58 FR 32383). Accordiagly, the amendment l
meets the eligibility criteria for categorical exclusion set forth in 10 CFR l
51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or l
environmental assessment need be prepared in connection with the issuance of the amendment.
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5.0 CONCLUSION
1 The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common i
defense and security or to the health and safety of the public.
Principal Contributor: Ronald W. Hernan Date:
September 1, 1993 l
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