ML20198J660
| ML20198J660 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/10/1997 |
| From: | Jeffery Wood CENTERIOR ENERGY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 2487, TAC-M98521, NUDOCS 9710210226 | |
| Download: ML20198J660 (3) | |
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. License Number NPF-3 Serial Number 2487 Docket Number 50-346 October 10. 1997' United States Nuclear Regulatory Commission
' Document Control Desk f'
Washington, D. C. 20555-0001
Subject:
Supplemental Information Regarding License Amendment Application to Revise Technical Specifications Regarding the Control Room Emergency Ventilation System Limiting Condition for Operation (LAR 97 0005; TAC No. M98521)
Ladies and Gentlemen:
The purpose of this letter is to provide supplemental information for a pending license amendment application regarding the Davis-Hesse Nuclear Power Station (DBNPS), Unit Number 1, Operating License Number NPF 3. The subject application, License Amendment Request (LAR) Number 97 0005, dated April _18,1997 (Toledo Edison Serial Number 2447),
involves proposed changes to Technical Specification (TS) 3/4.7.6, Plant Systems - Control Room Emergency Ventilation System (CREVS), and the associated Hases 3/4.7.6, Emergency Ventilation System. This supplemental information is provided in response to a j
verbal request from the NRC Staff to explain a variance between the proposed changes and NUREG-1430, "Imptoved Standard Technical Specifications for Babcock and Wilcox k p/
Pressurized Water Reactors," Revision 1.
Included in the changes proposed by LAR 97-0005 is a revision to the TS Limiting Condition for Operation (LCO) to include new required Actions in the event that one or both channels of Station Vent Ncrmal Range Radiation Monitoring instrumentation becomes inoperable. The
. present Action 3.7.6.1 would be renumbered as Action 3.7.6.1.a. and Actions 3.7.6.1.b and 3.7.6.1.c would be added, to read as follows:
- b. With one channel of Station Vent Normal Range Radiation Monito ing instrumentation
- inoperable, restore the inoperable channel to OPERAHLE status within 7 days, or within
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9710210226 971010
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PDR.ADOCK 05000346 P_
Docket Number 50 346 License Number NPF-3 Serial Number 2487 Page 2 the following i hour, isolate the control room normal ventilation system and place at ! east one control room emergency ventilation system train in operation.
- c. With both channels of Station Vent Normal Range Radiation Monitoring instrumentation inoperable, within I hour, isolate the control room normal ventilation system and place at least one control room emergency ventilation system train in operation.
As noted in the license amendment application, Improved Standard Technical Specification (ISTS) LCO 3.3.16, " Control Room isolation - liigh Radiation," requires only one radiation monitoring channel, and requires that the CREVS be placed in the emergency recirculation mode within I hour in the event the channel becomes inoperable in Modes I through 4. The license amendment application further notes that for the ISTS, the control roora isolation signal is provided by a single channel, whereas the DBNPS design has two channels.
The DBNPS license araendment application's proposed new Action statements specify that a CREVS train be placed in operation, whereas the applicable ISTS Action statement is more 3
specific in that it requires that a CREVS train be placed in the emergency recirculation mode.
This variance is intentional and is due to the plant-specific differences described in detail below.
The CREVS is described in Section 9.4.1," Control Room," of the DBNPS Updated Safety Analysis Report. The CREVS functions to provide a habitable environment in the control room following an accident. Operability of the CREVS, in conjunction with other control room design provisions, is based on limiting control room personnel exposure consistent with the requirements of General Design Criteria 19," Control Room," of Appendix A of 10 CFR 50.
During normal operation, the CREVS is held in standby. In the event of high radiation, the control room normal air conditioning system is shut down and the CREVS is manually activated.
The CREVS fans can be started from the control room either in the recirculation mode or the pressurization mode. In the recirculation mode, approximately 3300 cfm of control room air is recirculated through charcoal filter units. In the pressurization mode, approximately 300 cfm of fresh air is brought into the control room through charcoal filters while 3000 cfm of control room air is recirculated through charcoal filters. USAR Section 9.4.1.3, Revision 19, states that for the first four days following a LOCA, the control room will be isolated and the CREVS will be operated in the total recirculation mode (3300 cfm), and on the fourth day, the CREVS mode will be switched to take 300 cfm fresh air makeup while recirculating 3000 cfm. However, a change to the plant emergency procedure has been implemented, in accordance with 10 CFR 50.59, to require the CREVS to be operated in the outside air intake mode (i.e., pressurization mode) following a LOCA,in order to minimize unfiltered inleakage into the control room. An associated change to USAR Section 9.4.1.3 has been approved and will be included in the next scheduled US AR update submittal to the NRC.
The above-mentioned change in CREVS operation was a result of a CREVS design basis calculational error. The circumstances regarding this error were reported to the NRC on l
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Docket Number 50-346 License Number NPF-3 Serial Number 2487 Page 3 November 4,1996 as Licensee Event Report (LER)96-007. LER 96-007 committed to a re-evaluation of the assumptions used in the analysis for CREVS operation following a LOCA, followed by revisions to the USAR and af fected procedures. The NRC documented their review of this matter in Inspection Report No. 50-346/96014 dated February 25,1997 (Toledo Edison leg Number 1-3793), and documented close-out of the issue in inspection Report No. 50-346/97006 dated June 26,1997 (Toledo Edison Log Numbe:- 1-3855).
Accordingly, because the USAR analysis utilizes the pressurization mode, it is not appropriate to adopt the ISTS wording regarding operation of a CREVS train, under the provisions of the Action statement, in the " emergency recirculation mode." In preparation of the license amendment application, the DBNPS chose to include a proposed Bases 3/4.7.6 addition that provides additional detail on system operation, including a reference to US AR Section 9.4.1.
The LAR 97-0005 submittal concluded that the proposed changes have no adverse effect on nuclear safety, that the proposed changes do not involve a significant hazards consideration, and that the proposed changes do not constitute an unreviewed safety question. The supplemental information provided in this letter has no effect on these conclusions.
Should you have any questions or require additional information, please contact Mr. James L. Frects, Manager - Regulatory Affairs, at (419) 321-8466.
Very truly yours, d y.
Misillaj cc:
A.11. Beach, Regional Administrator, NRC Region til A. G. llansen, DB-1 NRC/NRR Project Manager S. Stasek, DB-1 NRC Senior Resident inspector J. R. Williams, Chief of Staff, Ohio Fmergency Management Agency, State of Ohio (NRC Liaison)
Uti'ity Radiological Safety Board
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