ML20209B336
| ML20209B336 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 01/30/1987 |
| From: | Bauer E, Bradley E, Gallagher J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | |
| Shared Package | |
| ML20209B318 | List: |
| References | |
| NUDOCS 8702040017 | |
| Download: ML20209B336 (17) | |
Text
i BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of Docket No. 50-352 PHILADELPHIA ELECTRIC COMPANY APPLICATION FOR AMENDMENT OF FACILITY OPERATING LICENSE NPF-39 Edward G. Bauer, Jr.
Eugene J. Bradley 2301 Market Street Philadelphia, Pennsylvania 19101 Attorneys for Philadelphia Electric Company hhh20Ahh7 P
P E
BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of Docket No. 50-352 PHILADELPHIA ELECTRIC COMPANY APPLICATION FOR AMENDMENT OF FACILITY OPERATING LICENSE NPF-39 Philadelphia Electric Company, Licensee under Facility Operating License NPF-39 for Limerick Generating Station Unit 1, hereby requests that the Technical Specifications contained in Appendix A of the Operating License be amended as indicated on the attached proposed revised page 3/4 7-7 of Appendix A.
The proposed change is indicated by a vertical bar in the margin of the page.
The change to the Technical Specifications proposed herein consists of an increase in the allowable control room air leakage rate from 525 cubic feet per minute (cfm) to 2100 cfm.
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Discussion Limerick Generating Station is designed with a common control room for Unit 1 and Unit 2.
A change to the LGS Technical Specifications for Unit 1 is being requested to increase the allowable control room air leakage rate from 525 cfm to 2100 cfm to accommodate cable pulling into the control room associated with the construction of Unit 2.
No physical system design changes are required to the normal Control Room HVt.0 or the Control Room Emergency Fresh Air Supply (CREFAS) system.
Both systems will continue to operate as designed.
The systems' 1
controls will compensate for the increased opening area by increasing the volume of outside air to the control room in order to maintain the control room pressurized relative to all surrounding spaces.
Operation of these systems with the increase in allowable control room air leakage rate will continue to assure that the operators are protected against postulated toxic chemical or radiation releases and will therefore have no adverse effect on the capability to safely operate the plant.
Relief is requested from the current Technical Specification control room allowable air leakage rate in order that cable pulling activities associated with the LGS Unit 2 construction remain on schedule.
Cable pulling into the control room under the current Technical Specification limit would delay the Unit 2 construction schedule by approximately three months with an estimated additional construction cost of $120 million. !
An increase in the Technical Specification control room allowable leakage rate from 525 cfm to 2100 cfm would allow Unit 2 cable pulling construction activities to remain on the current schedule.
The requested Technical Specification change is needed by April 15, 1987 in order to maintain the LGS Unit 2 construction schedule.
Systems Affected by the Proposed Change The systems affected by the proposed increase in the control room air leakage rate are the normal Control Room Heating Ventilation Air Conditioning (HVAC) system and the Control Room Emergency Fresh Air Supply (CREFAS) system which are common to both Units 1 and 2.
As discussed in FSAR Section 9.4, the control room HVAC system provides for the ventilation, cooling and control of environmental conditions in the control room envelope which is comprised of the control room, Shift Superintendent's office, general office, instrument shop and laboratory, toilet room, and utility room.
The system is served by two 100% capacity redundant supply air handling units and two 100% capacity return air fans.
Each supply unit contains a roll filter, chilled water cooling coils, a vane axial fan, and a humidifier.
During normal operation, one of the two supply air-handling units and one of the two return fans recirculate the control room air.
- Also, approximately 2100 cfm of fresh outside air is taken in at the control room ventilation system intake.
The control room is _.
normally maintained at 1/4 inch w.g. positive pressure relative to the turbine enclosure.
The outside makeup air and the recirculated air pass through a roll filter at the inlet of the air-handling unit fans.
The air is then cooled or heated by the air-handling units as required to maintain the desired t
temperature.
Upon loss of supply or return air flow, the respective standby fans automatically start, the associated fan dampers reposition; and an alarm annunciates in the control room.
As discussed in FSAR Section 6.4, the control room HVAC system is designed to ensure control room habitability after any of the design basis radiological accidents or a chemical release accident.
When high radiation is detected at the outside air intake, the control room outside air is automatically diverted through the CREFAS system.
All habitability zone isolation valves in the control room HVAC system close, except those on the emergency fresh air intake.
When chlorine or a monitored toxic gas is detected at i
the outside air intake, the high-chlorine or toxic chemical alarm is annunciated in the control room.
All isolation valves in the control room HVAC system close automatically on detection of chlorine or are closed remote manually by operating personnel on detection of other toxic chemicals.
As discussed in FSAR Section 6.4, after control room isolation is completed, the CREFAS system is started and operated to recirculate and clean up the air in the control room.
The outside air intake valves remain closed i
during this mode of operation.
The CREFAS system consists of two banks of 100% capacity air filtration trains consisting of an electric heating coil, prefilter, high-efficiency particulate air (HEPA) filter, carbon adsorber, second HEPA filter, and a 3000 cfm fan (FSAR Section 9.4.1.3).
Safety Discussion The proposed change to Technical Specification 3.7.2 is an increase in the allowable control room air leakage rate from 525 cfm to 2100 cfm.
The current Technical Specification limit for control room air leakage rate of 525 cfm is equivalent to 0.25 air changes per hour.
The limit was established using the methodology described in NUREG/ control room-1741.
The maximum leakage rate is bounded by considerations for toxic chemical releases, radiological releases, and the ability of the normal control room HVAC system and the CREPAS system to maintain the control room pressurized relative to surrounding spaces.
If the maximum leakage rate is increased from 525 cfm to 2100 cfm, the normal control room HVAC system will still be able to maintain the control room pressurized relative to surrounding spaces, as stated in SER Section 9.4.1 and FSAR Section 9.4.1.7.
Since 2100 cfm is within the 3000 cfm makeup capability of CREFAS, this system will still be able to maintain the control room at its current Technical Specification limit of + 1/8" w.g.
relative to all surrounding spaces. -
The existing FSAR toxic chemical and radiological analyses have been evaluated for the effect of increasing the allowable control room leakage rate.
The same methods and assumptions of the existing FSAR analyses were used, as described in FSAR Section 2.2.3.1.3 (hazardous chemicals) and FSAR Section 15.10.2 (radiological).
The analysis shows that up to 3000 cfm, the control room leakage rate is acceptable for both considerations and the normal HVAC system can maintain the control room pressurized at the new leakage rate.
A.
Radiological Analysis The results of the radiological analysis presented in the FSAR (Table 15.6-22) indicate that the control room doses contain sufficient conservatism to allow a substantial increase in the control room leakage rate.
A leakage rate of 3000 cfm can be accommodated without exceeding the GDC-19 criteria.
This leakage rate would still leave a substantial margin before reaching the GDC-19 criteria as shown in Table 1.
These results were obtained using the same methods previously used in FSAR Sections 15.6 and 15.10.2.
A control room analysis, which approximated the assumptions used in the Safety Evaluation Report (SER) offsite dose analysis, was also performed.
This analysis uses a different method for evaluating control room doses than that used in the FSAR.
Section 6.4 of the SER indicates the control room doses are __
" acceptable", but no detailed information on the control room analysis was presented.
The FSAR control room atmospheric dilution factor (X/Q) values were used in the estimate to determine the results of an "NRC control room analysis" for a higher leakage rate.
The results of this SER type analysis indicate that the thyroid doses increase significantly, but because the beta skin dose is still limiting, the GDC-19 criteria are still met.
Independent of the NRC type control room analysis results discussed above, the current licensing basis presented in FSAR Table 15.6-22 is being changed to that shown in Table 1.
B.
Toxic Chemical Analysis The toxic chemical release events described in FSAR Section 2.2.3.1.3, which discusses both chlorine and other toxic chemicals, are not postulated to occur in conjunction with radiological release events and, therefore, are not bounded directly by Technical Specification 3.7.2.
However, the proposed Technical Specification indirectly increases the allowable exfiltration/ infiltration rate which in turn affects the toxic chemical analysis.
Analysis shows that up to 3000 cfm leakage rate could be accommodated while still maintaining at least 2 minutes for operator protective action in accordance with Regulatory Guide 1.78 for toxic chemical events.,.
a.
Chlorine For chlorine, the analysis assumes that the detectors function properly, as described in FSAR Section 6.4.3.2.1, and the control room is isolated upon detection.
Inleakage into the control room would come from the cable spreading room or the auxiliary equipment room.
Credit was taken for dilution of leakage from the cable spreading room and auxiliary equipment room.
The results show that up to 3000 cfm leakage rate can be tolerated before reaching incapacitation level.
1 b.
Other Toxic Chemicals A parametric study at various leakage rates was performed for the remaining 15 chemicals originally identified as posing a hazard.
Detectors are installed for six of these chemicals, as discussed in FSAR Section 2.2.3.1.3.
For ether toxic chemicals, the control room is manually isolated as described in FSAR Section 6.4.3.2.3.
The times to reach incapacitation level frcm monitor setpoints l
were determined by varying the control room leakage i
rate from 525 cfm through 4000 cfm and assuming no control room isolation, as was done in the previous FSAR analysis.
For the chemicals detected in the control room, ethylene oxide is limiting at 3200 cfm.
This analysis used the same criteria for,- _
elimination of chemicals from monitoring as in the current FSAR toxic chemical analysis (FSAR Section 2.2.3).
Thus, increasing the Technical Specification limit for the control room air leakage rate to 2100 cfm is determined to be acceptable.
Significant Hazards Consideration Determination The Commission has provided guidance concerning the application of standards in 10 CFR 50.92 for determining whether license amendments involve significant hazards consideration by providing certain examples (51 FR 7750-51) of amendments that are considered not likely to involve significant hazards consideration.
Example (vi) is "a change which either may result in some increase to the probability or consequences of a previously analyzed accident or may reduce in some way a safety margin, but where the results of the change are clearly within all acceptable criteria with respect to the system or companent specified in the Standard Review Plan, e.g. a change resulting from the application of a small refinement of a previously used calculational model or design method."
The foregoing requested change fits this example as an item not involving any significant hazards.
The change in allowable flow rate results in a small decrease of the margin of safety for control room habitability and the results of the change are within all acceptable criteria in Standard Review Plan 6.4.
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The proposed amendment to the Limerick Operating License does not constitute a significant hazards consideration in that it would not:
(1) involve a significant increase in the probability or consequences of an accident previously evaluated because the new leakage rate of 2100 cfm is within the makeup capability of the normal control room HVAC system, as described in FSAR Section 9.4.1, to keep the control room pressurized.
The impact to toxic chemical or radiological releases and control room habitability, as discussed in FSAR Section 6.4, is unchanged.
An increase in the leakage rate to 2100 cfm does not increase the probability of chemical or radiological releases evaluated in FSAR Section 2.2.3 and 15.10.2, respectively.
The capability to maintain a positive control room pressure of at least 1/8" w.g.
relative to surrounding spaces during a design basis radiological release and provide sufficient time for operator response during a toxic chemical release is unchanged as discussed in FSAR Section 6.4.
Both the probability of release of toxic chemicals and the probability of an accident which would release radiation to the environment are independent of the control room leakage rate.
The radiological effects on the control room personnel that could exist as a result of the postulated design I
basis accidents described in FSAR Sections 15.6 and 15.10.2 remain less than GDC-19 limits as shown in Table 1.
The operators still have greater than 2 minutes to take the protective action of donning breathing apparatus following both off-site and on-site toxic chemical releases in accordance with Regulatory Guide 1.78.
Under the previous analysis, the limiting chemical was phosgene at 3.5 minutes.
Under the current analysis, the limiting chemical is ethylene oxide at 2.3 minutes.
Releases of off-site and on-site chemicals, as described in FSAR Section 2.2.3, were considered in this conclusion.
Therefore, increasing the control room leakage rate does not increase the consequences of either a postulated toxic chemical release or radiation release to the environment.
Under the previous analysis, the operators were protected against the postulated releases and retained the capability to safely operate the plant.
The revised control room leakage rate still assures that the operators are protected against postulated releases and, therefore, still retain the capability to safely operate the plant.
There were no consequences of the postulated releases under the previous analysis, and there are still no consequences.
(2) create the possibility of a new type of accident or a different kind of accident from any accident previously analyzed because allowing increased leakage during normal HVAC and CREFAS operation neither physically alters either system nor does it affect the performance of any other system.
Both. systems retain the capability to maintain the control room at a positive pressure
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relative to the surrounding spaces as discussed in FSAR Section 9.4.1.
The analyses at the proposed increased air leakage rate are based on the existing design basis radiological accident described in FSAR Sections 15.6 and 15.10.2 and releases of toxic chemicals as described in FSAR Section 2.2.3.
No new or different types of accidents are created by increasing the allowable leakage rate into the control room.
(3) involve a significant reduction in the margin of safety.
While the control room doses following the postulated design basis accidents described in FSAR Sections 15.6 and 15.10.2 are increased with the higher leakage rate, the reduction in the margin of safety is minimal as shown in Table 1.
The reduction in the margin of safety is acceptable for the reasons stated in the first paragraph of this Determination.
Under the current Technical Specification 3.7.2 limit, control room doses are well below GDC-19 limits and they remain well below GDC-19 limits with the proposed increase in leakage rate as shown in Table 1.
While the impact of toxic chemical i
releases on the control room operators, as described in I
l FSAR Section 2.2.3, is increased by the additional I h
L A
leakage rate, the change in the margin of safety is acceptable for the reasons stated in the first paragraph of this Determination.
Under the current Technical Specification 3.7.2 limit, the operators have greater than two minutes as described in Regulatory Guide 1.78 to take protective action.
They still have greater than two minutes for these protective actions under the proposed Technical Specification limit.
TABLE 1 CONTROL ROOM DOSES FOR PROPOSED TECHNICAL SPECIPICATION CHANGE TO INCREASE LEAKAGE RATE TO 2100 CFM 10CFR50 Current New Doses GDC 19 Tech Specs Tech Specs (Rem)
Requirement (525 cfm)
(2100 cfm)
Thyroid 30
.0043
.018 Beta Skin 30 7.6 8.9 Whole Body 5
.38
.47 Note:
Current Technical Specification values were obtained from FSAR Table 15.6-22 l l
Conclusion The proposed technical specification change will affect the allowable air leakage rate for the control room HVAC.
The normal control room HVAC system will be able to maintain the control room pressurized relative to surrounding spaces as required by SER Section 9.4.1 and FSAR Section 9.4.1.7.
The safety-related CREFAS system will still be able to maintain the control room at its current Technical Specification limit of at least + 1/8" w.g. relative to the surrounding spaces.
Analyses have determined that the increase in the leakage rate limit will meet the acceptance criteria established in the FSAR for radiological and toxic gas considerations.
The proposed amendment does not constitute a significant hazards consideration.
Environmental Considerations The requested amendment will not result in a change in the amounts or types of effluents that may be released off-site.
There will be no significant increase in individual or cumulative occupational radiation exposure as a result of the requested amendment.
The Plant Operations Review Committee and the Nuclear Review Board have reviewed these proposed changes to the Technical Specifications and have concluded that they do not involve an unreviewed safety question or a significant hazards consideration and will not endanger the public health and safety.
Respectfully Submitted, PHILADELPHIA ELECTRIC COMPANY h
CVice Presid&nt COMMONWEALTH OF PENNSYLVANIA ss.
COUNTY OF PHILADELPHIA J. W. Gallagher, being first duly sworn, deposes and says:
That he is Vice President of Philadelphia Electric Compr.ny, the Applicant herein; that he has read the foregoing Application for Amendment of Facility Operating Licenses and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.
bhL -
C.)
O Subscribed and sworn to before me this 3 ay o f /) c n n ME7 p, A f.
A Notary Public NELANIE R. CAMPANELLA Notary Public, Philadelphia, Philadelphia Co.
Vy Commission bpires February 12,1990 l
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