ML20059B907
| ML20059B907 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 10/22/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20059B904 | List: |
| References | |
| NUDOCS 9310290142 | |
| Download: ML20059B907 (4) | |
Text
-
goacog fY
[
UNITED STATES i
j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 206664001
%~.../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0. 56 TO FACILITY OPERATING LICENSE NO. NPF-37 AND AMENDMENT NO. 56 TO FACILITY OPERATING LICENSE NO. NPF-66 COMMONWEALTH EDIS0N COMPANY BYRON STATION. UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-454 AND STN 50-455
1.0 INTRODUCTION
]
By letter dated July 27, 1992, Commonwealth Edison Company (Ceco, the licensee) submitted a request for several proposed changes to the Byron j
Technical Specifications (TS), Specifically, the proposed changes would i
modify the control room ventilation heater dissipation requirement and the nonaccessible area exhaust filter plenum ventilation system flow rate, would eliminate-bank flow testing for the nonaccessible area exhaust filter plenum ventilation system, would make several editorial changes, and would allow the use of hot 'di-2-ethylhexyl phthalate (D0P) testing.
2.0 EVALUATION 2.1 Control Room Ventilation Heater Dissipation Currently, TS 4.7.6.e.4 requires verification that the control room ventila-tion heaters dissipate 27.2 2.7 kW when tested in accordance with ANSI
)
N510-1980.
The Updated Final Safety Analysis Report, section 6.5.1.2.1.d.2 states that the single-stage electric heater is sized to reduce the humidity of the airstream to at least 70% relative humidity for the worst inlet conditions. Further, that a heater capacity of 23.8 kW was calculated using 110% of the filter design flow rate and entering air conditions of 95'F and 100% relative humidity. This calculated minimum required heater capacity is a revision of the original design basis for the heaters. The revision is based on a revised assumption that the air within the turbine building, the emergency source of the suction for the control room emergency air filter units, is identical with the atmospheric conditions for the design basis accident condition. This change in assumption reduced the calculated heating requirement from 92,860 Btu /hr (27.21 kW) to 23.8 kW.
Based on, in part, this revised calculation, the licensee has proposed a change to the TS to verify that the heaters dissipate greater than or equal to 24.0 kW when tested in accordance with ANSI N510-1980. The proposed revision of the minimum acceptable value from 24.5 kW (27.2 - 2.7) to 24.0 kW is acceptable as this meets the requirements of the revised design calculation. The proposed change deleting the maximum acceptable value of 29.9 kW (27.2 + 2.7) is acceptable as an increased heat dissipation will not degrade the heaters capability to 1
E 9310290142 931022 PDR. ADOCK 05000454 P
perform their design function and the licensee will continue to have administrative controls to protect the heaters themselves from excessive voltage / current for equipment operability.
2.2 Nonaccessible Area Exhaust Filter Plenum System Flow Rate The purpose of the nonaccessible area exhaust filter plenum ventilation (VA)_
system is to direct radioactive materials, that may leak from the ECCS equipment within the pump rooms following a LOCA, to filters prior.to reaching the environment. The design nonaccessible area exhaust filter plenum flow rate is based on minimizing airborne contamination for ALARA and maintaining area temperatures appropriate for equipment qualification. Original plant design calculations established a plenum design flow rate of 66,900 cfm based on calculated room heat loads. Currently, TS 4.7.7 requires VA system flow to be 66,900 cfm i 10%.
During Byron, Unit 2, startup testing, the VA system flow rates were less than originally calculated.
Due to this discrepancy, the calculated room heat loads were reassessed and the minimum acceptable air flow rate was recalculated. Specifically, the revised minimum acceptable system flow rate was calculated to be 55,669 cfm and the revised system design flow rate was calculated to be 62,730 cfm. As a result, the licensee has proposed to revise the TS lower bound and nominal flow rate to be the revised calculated minimum acceptable and design flow rates, respectively. The upper bound is proposed to be 110% of the filter rated capacity of 62,000 cfm, or 68,200 cfm. Ceco's engineering calculations demonstrated that the lower flow rates were acceptable for both the total ventilation requirement and for the individual room ventilation requirement. The lower flow rates will increase residence time in the charcoal adsorbers, which will improve filtration efficiency. The-absolute pressure in the auxiliary building is not significantly changed by the new flow rate and, therefore, the differential pressure between the control room and adjacent areas is unaffected.
Based on the above, the proposed change to the nonaccessible area exhaust filter plenum ventilation j
system flow rate is acceptable.
1 2.3 VA System Bank Flow Testina Currently, several of the surveillance requirements _in section 4.7.7 for the non-accessible area exhaust filter plenum require verification of both total system flow and flow in each train of the system.
Ceco is proposing that the individual train flows be verified only after any structural maintenance or modification to the filtar housing.
The flow distribution for the VA Nonaccessible plenums was set during initial construction by installation of welded baffle plates. Since there are no i
moveable dampers controlling flow distribution there is no reason for the flow distribution to change. The initial startup test program verified that the -
flow distribution was acceptable and subsequent surveillances have found no j
change in the air flow distribution since the baffle plates were installed.
Current plant procedures OBVS XDP-1 requires a monthly surveillance of the j
1
' differential pressure across each on-line HEPA filter and procedure OBVS 7.7 b.1-1 requires an 18-month visual inspection of the HEPA filter banks.
These surveillances will provide adequate assurance that the HEPA filters have not become clogged.
In addition, the performance of the bank flow verification requires that plant staff take measurements inside the plenums while the fans are in operation. This poses a potential' safety hazard.
Based on the fixed flow controls for the plenums and the implementation of a verification surveillance should modifications be performed, the deletion of the current bank flow surveillance requirement is acceptable.
']
The licensee has also proposed revised upper and lower bounds for the new.
post-maintenance bank flow surveil?ance requirement. These new flow rates were calculated by evenly dividing the revised VA system flow rate (see above).
This provides for an evenly distributed flow, and is, therefore, acceptable.
2.4 DOP Testina i
Currently, TS Surveillances 4./.7.b.4 and 4.9.12.b.4 specify that cold DOP (di-2-ethylhexyl phthalate) is to be used for testing the VA system. The licensee has proposed to replace the requirement for " cold" D0P testing with non-specified D0P testing.
In support, the licensee references ANSI N510-1980 which allows the use of " cold" or " hot" D0P.
" Cold" DOP refers to a D0P aerosol generated by a particular method which uses compressed air.
For in-place testing using a DOP aerosol, the critical parameter is the distribution of droplet sizes in the aerosol. Any method of generating the droplet size distribution specified in ANSI N510-1975, 1980, or 1989, satisfies the guidance of Regulatory Guide 1.52 with regard to in-place testing using D0P.
Based on the licensee's reference to ANSI N510-1980, the deletion of the
" cold" specification for D0P testing is acceptable.
2.5 Editorial Chanaes The licensee proposed the deletion of a footnote to TS 3.7.7, stating that the requirement is not applicable prior to July 1,1985, and the deletion of a footnote to TS 4.7.7.d.3 stating that the requirement is not applicable to Unit 2 until October 1, 1987. Since both of these dates are now passed and the footnotes are no longer necessary, their deletion is acceptable. The i
licensee also proposed to correct a typographical error in TS 4.7.7.b.2 which refers to methyl "idodide" when it should read methyl " iodide." This change is also acceptable.
In addition, during the review of this proposed amendment, a footnote on page 3/4 7-22 was noted as no longer applicable.
Specifically, the footnote required that "The visual. inspection of the inaccessible snubbers for Unit 1, Cycle 3 must be completed by January 24, 1990." The time frame for this requirement has now passed. Therefore, the deletion of the footnote is acceptable.
I i
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Illinois State official was notified of the proposed issuance of the amendments.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be releaseo offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendments involve no significant hazards consider-ation, and there has been no public comment on such finding (57 FR 48815).
Accordingly, the amendments meet 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 amendments.
5.0 CONCLUSION
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 amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principa'l Contributor: John B. Hickman Date:
October 22, 1993
.