ML20214U210
| ML20214U210 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/02/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20214U200 | List: |
| References | |
| NUDOCS 8706110093 | |
| Download: ML20214U210 (4) | |
Text
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NUCLEAR REGULATORY COMMISSION o
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION J
SUPPORTING AMENDMENT NO. 5 TO FACILITY OPERATING LICENSE NO. NPF-39 4
PHILADELPHIA ELECTRIC COMPANY LIMERICK GENERATING STATION, UNIT 1 i
DOCKET NO. 50-352 1.0 INTRC"UCTION By l'etter dated ~ January 30, 1987, as supplemented on March 27, May 13 and 1
May 20, 1987, Philadelphia Electric Company (the licensee) requested an amendment to Facility Operating License No. NPF-39 for. the Limerick Generating Station, Unit 1.
The proposed amendment would change Technical Specification (TS) surveillance requirement 4.7.2.e.3 to allow.an increase from 525 cubic feet per minute (cfm) to 2100 cfm in the amount of outside -
air which must be taken in by the control room (CR) heating, ventilating 3
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and air conditioning (HVAC) systems in order to maintain a control room 4
internal positive pressure of at least one-eighth inch water guage-(in.)
during a radiation isolation mode of operation of the control room habit-ability systems. The change was requested to facilitate cable. pulling i
associated with the construction of Unit 2.
The systems affected by the proposed increase in the control room air l
leakage rate are the nomal Control Room Heating Ventilation Air Condi-j tioning)(HVAC) system and the Control Room Emergency Fresh Air Supply-(CREFAS system which are comon to both Units 1 and 2.
During nomal i
operation, fresh outside air is taken in at the control room ventilation
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system intake which maintains positive pressure in the control room relative t'o the surrounding speces. When high radiation is detected at the outside air intake, the control room outside air is automatically i
diverted through the CREFAS system. All isolation valves in the control room HVAC system close, except those on the emergency fresh air intake.
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When chlorine or a monitored toxic gas is detected at the outside air.
intake, the high-chlorine or toxic chemical alam is annunciated in the i'
automatically on detection of chlorine or are closed remote manually by control room. All isolation valves in the control room HVAC system close operating personnel on detection of other toxic chemicals. After control.
room isolation is completed, the CREFAS system is started and operated to i
recirculate and clean up the air in the control room. The outside air intake valves remain closed during this mode of operation.
The CREFAS system consists of two 100%: capacity air filtration trains consisting of high-efficiency particulate air (HEPA)' filters and charcoal filters and process 3000 cfm of outside air.
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l 2.0 EVALUATION The proposed TS change will not result in a change to the physical design of the system.
In addition, it will not result in any significant change to the normal operational mode of the HVAC system and CREFAS system, since i
they normally supply about 2100 cfm of air to the control room. The ability to pressurize the control room to a specific value with a given l
flow rate is a measure of the control room's leaktightness. A control 4
room admitting 2100 cfm in:tead of 525 cfm, in the radiation isolation mode would require the CREFAS system to process the increased flow before supplying it to the control room. The value of 2100 cfm is within the 3000-cfm capability _of the CREFAS system as discussed above. The system's controls will compensate for the increased opening by increasing the volume of outside air to the control room in order to keep the control room pressurized relative to all surrounding spaces. Thus, we conclude j
that 2100 cfm is within the 3000-cfm capability of the CREFAS system and this system will be able to maintain the control room at a positive pressure of at least 1/8-inch water gauge relative to all surrounding spaces during a radiation isolation mode of operation of the control room habitability systems.
The licensee has evaluated the change in the radiological doses to the control room operators resulting from the increased leakage in the control room during a radiation isolation mode. The results of the analysis are provided in Table 1.
The analysis of the proposed increased air leakage rate is based on the existing design-basis radiological accidents described in FSAR Sections 15.6 and 15.10.2. Table 1 shows that although there will be an increase in the computed doses to the control room operators as a result of a high-radiation accident, the dose remains within the limits established in tue Standard Review Plan (SRP)'Section 6.4 (NUREG-0800) and General Design Criterion (GDC) 19 of 10 CFR 50, Appendix A.
The licensee has also evaluated the effect of increased flow on the consequences resulting from chlorine or other toxic chemical release accidents. The analysis is based on the existing design-basis accidents i
described in FSAR Section 2.2.3 for releases of toxic chemicals. No new or different types of accidents have resulted by increasing the allowable leakage rate into the control room.
i Since the allowable inleakage to the control room would be increased by the proposed amendment, the time available to the operators to don protec-tive breathing apparatus before there is an unacceptable increase in the-concentration of chlcrine or other toxic chemicals in the control room atmosphere is reduced. Under previous analysis, the limiting chemical was q
ethylene oxide at 2.6 minutes. The new analysis indicates that the ifmiting chemical remains ethylene oxide with an incapacitation time of 2.1 minutes based on the assumption of an unisolated control room. The 2.1-minute period is within the protective action limit of 2 minutes-for donning breathing apparatus following both offsite and onsite toxic chemical releases. Thus, the guidelines of Regulatory Guide 1.78, "Assump-j l
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tions for Evaluating the Habitability of a Nuclear Power Plant Control l
Room During a Postulated Hazardous Chemical Release," Positions C.3, C.7 and C.14, are satisfied.
The staff notes that the ability to pressurize the control room to a specific.value with a given flow rate is a measure of the control room's leaktightness. Therefore, after the construction of Unit 2 is complete, i
the staff believes that the allowable control room air intake rate during the radiation isolation mode should revert to 525 cfm. The licensee agreed with a change which would result in reverting to the'525 cfm value upon completion of Unit 2. construction and issuance of the Unit 2 full power license. The licensee reflected this change in-its letter of May 20, 1987.
1 On the basis of the above considerations, the staff concludes that the f
proposed change to the surveillance requirement in TS 4.7.2.e.3, that is, an increase in allowable control room outside air intake during operation of the control room emergency fresh air supply system in the radiation isolation mode, complies with the General Design Criterion 19 of 10 CFR 50, Appendix A, and the guidelines of Regulatory Guide 1.78 with respect to control room operator doses and the release of toxic chemicals, and is, therefore, acceptable during the construction of Unit 2.
3.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change to a requirement with respect to the 7
installation or use of a facility component located within the restricted 1
area as defined in 10 CFR Part 20 and changes the surveillance requirement.
The staff has determined that the amendment invol_ves no significant i
increase in the amounts, and no significant change in the types, of any l
l effluents that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure.
j The Comission has previously issued a proposed finding that this amendment i
involves no significant hazards consideration and there has been no public l
coment on such finding. Accordingly, this amendment meets the eligibility i
criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant.
to 10 CFR 51.22(b), no environmental impact statement nor environmental assessment need be prepared in connection with the issuance of this amendment.
4.0 CONCLUSION
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The staff has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of thel l
l public will not be endangered by operation in the proposed manner, and i
(2) such activities will be conducted in compliance with the Comission's regulations and the issuance of this amendment will not be inimical to the comon defense and the security nor to the health and safety of the public.
Principal Contributor:
R. Anand.
Dated: June 2, 1987 I
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Enclosure Table 1 Control Room Doses For Proposed Technical Specification Change to Increase Leakage Rate TO 2100 CFM 10 CFR 50 Current New 1
Dose GDC 19 Tech Specs Tech Specs (rem)
(525 cfm)
(2100 cfm) 2 Thyroid 30 0.0043 0.018 2
Beta skin 30 7.6 8.9 Whole body 5
0.38 0.47 Note:
- 1. Current Technical Specification values were obtained from FSAR Table 15.6-22.
- 2. Although GDC 19 of 10 CFR 50, Appendix A, does not explicitly give requirements pertaining to thyroid and beta skin doses, SRP Section 6.4.II.6 gives the listed values.
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