ML20236W545
| ML20236W545 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 12/01/1987 |
| From: | Ross T Office of Nuclear Reactor Regulation |
| To: | Harrison J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 8712080082 | |
| Download: ML20236W545 (1) | |
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December 1,1987 l
DISTRIBUTION MEMORANDUM FOR: John J. Harrison, Chief D cket Filew OGC-Beth.
Engineering Branch NRC & Local PDRs EJordan Region III PD3-2 R/F JPartlow GHolahan ACRS (10) ther PD3-2 Plant File FROM: Thierry H. Ross, Project Manager Project Directorate III-2 Nuclear Reactor Regulation
SUBJECT:
APPENDIX R SAFETY EVALUATION AND REQUEST FOR INSPECTION SUPPORT REGARDING HOT SHUTDOWN REPAIRS (50-254/265) l Attached for your information is the NRR safety evaluation (SE) issued to Commonwealth Edison Company (CECO, the Licensee) for Quad Cities Nuclear Power Station (QCNPS) regarding 10 CFR 50, Appendix R Section 111.0.1 exemption requests and miscellaneous related submittals. Additional licensee requests for Appendix R technical exemptions related to fire protection features for specific plant areas at QCNPS are still under review. Every effort will be made to issue this other SE by December 11,1987, in order to support the RIII Appendix R compliance inspection scheduled for December 14 thru 18, 1987 at QCNPS. Due to the short amount of time available, actual " Exemptions" will not be issued to CECO or published in the Federal Register prior to the RIII team inspection, but should come very soon thereafter.
With regard to the attached SE, NRR requests RIII to assess and verify licensee's abilities to perform the approved manual actions (i.e. hot shutdown repairs) in a timely fashion. Several of these repairs (i.e. fuse pulling and/or replacement) are required to be accomplished by operators in a limited period of time (e.g.10 minutes) and encompass many fuses (e.g. Fire Area TB-III, 27 fuses pulled and 3 replaced) at different locations. The purley technical aspects of hot shutdown repairs for QCNPS were considered acceptable, and CECO has affirmed they can accomplish all these critical manual actions in the time required. However, due to the complexities involved and the potential safety significance of such actions, RIII should examine selected portions of the licensee's performance and procedures, for accomplishing hot shutdown repairs, during the upcoming Appendix R compliance inspection. This subject and request was previously discussed with RIII (J. Holmes) and Brookhaven National Labs (K.Sullivan) on June 9, 1987.
Original Signed by/
Thierry M. Ross Project Manager-Quad Cities PM/PD3 RSP: PD/PD32/DRSP:
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Dockets Nos. 50-254 December 1,1987 l and 50-265 Mr. L.D. Butterfield, Jr.
Nu: lear Licensing Manager Commonwealth Edison Company Post Office Bax 767 Chicago, Illinois 60690 '
Dear Mr. Butterfield:
SUBJECT:
INTERIM COMPENSATORY MEASURES AND REQUEST FOR EXEMPTION FROM 10 CFR PART 50, APPENDIX R, SECTION III.G.1 REGARDING HOT SHUTDOWN REPAIRS (TAC NOS. 57284,57285,64493AND64494)
By letter dated December 18, 1984, Commonwealth Edison Company (CECO, the licensee ) submitted a reevaluation report pertaining to 10 CFR Part 50, Appendix R (Fire Protection Program) for Quad Cities Nuclear Power Station (QCNPS) in response to NRC staff positions prescribed in Generic Letter 83-33, dated October 19, 1983. This report identified Interim Compensatory Measures (ICMs) that were being conducted at QCNPS for an interim completion of Appndix R required hardware modifications) period (until to ensure safe shutdown capability of Units 1 or 2 for postulated fire events. Based on a review of the aforementioned report, the NRC staff has determined that the previous staff safety evaluation (SE) and approval of safe and alternative shutdown capabilities at QCNPS, issued December 30, 1982, remains valid.
However, during the staff's review, additional information was requested from CECO concerning the affect of fire-induced high impedance faults and electrical isolation deficiencies upon safe shutdown capability at QCNPS for certain fire events. These issues were not explicitly addressed in the reevaluation report.
Additional information was also sought on the ICMs.
Ceco responded to the staff's inquiries with letters dated December 30, 1986, March 13, 1987, July 15, 1987, and October 9, 1987. In these submittals, CECO proposed conducting certain manual operations, including hot shutdown repairs (i.e., pulling out fuses and/or replacing blown fuses), to resolve the issues above, and resolve problems with fire-induced spurious operations that were subsequently self-identified. In general,Section III.G.1 requirements have been interpreted to prohibit hot shutdown repairs. Consequently, CECO i submitted letters dated January 12, 1987, September 30, 1987, October 1,1987,
) November 20, 1987, and November 30,1987, requesting approval for several i
exemptions from Appendix R,Section III.G.1 which would allow such repairs in order to achieve and maintain hot shutdown.
In the March 13 1987 letter, CECO stated that because all the required safe shutdown hardwar,e modifications had been completed, their corresponding ICMs would no longer be necessary. Also, in a July 17, 1987 letter, several deviations between the present safe shutdown program, and what was approved in the previous NRC SE (dated December 30,1982), were described by CECO anc 7s q gn . a /! r v -f"TU b,c,-U) \ 1 ' ' '
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technically justified. Futhermore, in the letter dated November 20, 1987 CECO i notified the staff _that a portion of an exemption request, 10.0 " Hot Shutdown Repairs (Fuse Replacements)" in the September 30, 1987, letter was no longer necessary dus to a non-Appendix R related plant modification to be accomplished
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during the Unit I refueling outage. Consequently, that part of the exemption request related to the Unit I Reactor Core Isolation Cooling System inboard steam supply isolation valve was withdrawn.
Enclosure 1 of this letter contains the NRC staff SE, which encompasses all the aforementioned CECO submittals except for two subject requests described below.
It was the staff's conclusion that the manual actions, including hot shutdown repairs, proposed by CECO to resolve concerns of high impedance faults, electrical isolation deficiencies, and spurious operations were acceptable; and applicable exemptions requests (for performing hot shutdown repairs) should be granted.
The staff also concluded that deviations described by the July 17, 1987 letter would not compromise the safe shutdown capability at QCNPS and are therefore, acceptable. Furthermore, the staff recognizes that ICMs specified in Enclosure 2 of the reevaluation report dated December 18, 1984 are no longer required. It should also be noted, CECO submitted two additienal letters, not previously mentioned, dated July 23,1987 and December 2,1987. These letters were provided to the staff for information purposes only, as such no formal evaluation was performed.
Technical exemption requests from Section III.G of Appendix R, contained in Enclosure 3 of the December 18, 1984 reevaluation report, related to fire protection features for selected plant areas will be evaluated by the staff in a separate SE to be issued later. A schedular exemption from compliance with 10 CFR 50.48 was requested by letter dated November 20, 1987. This subject will also be evaluated separately and issued later. The legal regulatory
" Exemption", that exempts certain hot shutdown repairs at QCNPS from compliance with requirements of 10 CFR 50, Appendix R, Section III.G.1 will be issued to CECO and published in the Federal Register by other separate correspondence, which should be forthcoming.
Original Signed by/
Thierry M. Ross, Project Manager Project Directorate III-2 Division of Reactor Projects III, IV, Y and Special Projects
Enclosures:
DISTRIBUTION L) Safety Evaluation Docket File OGC-Bethesda NRC & Local PDRs EJordan cc w/ enclosures: PD3-2 Rdg. File JPartlow Docket Nos. 50-254 GHol ahan PD3-2 Plant File and 50-265 LLuther ACRS (10)
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Mr. L. D. Butterfield, Jr. Quad Cities Nuclear Power Station Commonwealth Edison Company Units 1 and 2 cc:
Mr. Stephen E. Shelton Vice Presiderit -
Iowa-Illinois Gas and Electric Company P.O. Box 4350 Davenport, Iowa 52808 Mr. Michael Miller Isham, Lincoln & Beale Three First National Plaza Suite 5200 Chicago, Illinois 60602 Mr. Richard Bax Station Manager Quad Cities Nuclear Power Station 22710 206th Avenue North Cordova, Illinois 61242 Resident Inspector U.S. Nuclear Regulatory Commission 22712 206th Avenue North Cordova, Illinois 61242 Chairman Rock Island County Board of Supervisors 1504 3rd Avenue Rock Island County Office Bldg.,
Rock Island, Illinois 61201 Mr. Michael C. Parker, Chief Division of Engineering Illinois Department of Nuclear Safety 1035 Outer Park Drive Springfield, Illinois 62704 Regional Administrator, Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137
Enclosure 1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PLANT SYSTEMS BRANCH INTERIM COMPENSATORY MEASURES AND REQUEST FOR EXEMPTION FROM 10 CFR PART 50, APPENDIX R, SECTION III.G REQUIREMENT _
REGARDING HOT SHUTDOWN REPAIRS FOR A FIRE EVENT IN THE PLANT QUAD CITIES, UNITS 1 AND 2 DOCKET NOS. 50-254 and 50-265
1.0 INTRODUCTION
On December 30, 1982, the NRC issued a Safety Evaluatien Report (SER) relating to Sections III.G.3 and III.L of 10 CFR Part 50, Appendix R (alternative / dedicated '
shutdown capability for a reactor following a fire event in the plant) for l Quad Cities, Units 1 and 2, wherein the staff concluded that the plant met the j requirements of the above sections with regard to alternative shutdown capability.
Subsequently, by letter dated December 18, 1984, Commonwealth Edison, the licensee for the plant, submitted an Appendix R reevaluation report stating that it was necessitated by Generic Letter 83-33, dated October 19, 1983 which l defined NRC staff positions on certain Appendix R requirements. In the above i submittal, the licensee identified the Interim Compensatory Measures (ICMs) needed to ensure safe shutdown of the plant following a fire event in the plant during the interim period (i.e., until the permanent hardware modifications are completed). The report additionally contained a request for exemption from specific III.G requirements relating to fire protection l features for select areas. Based on a review of the submittal, the staff has i determined that the safe shutdown capabilty including the alternative shutdown l capability at the plant continues to be essentially the same as that described l by the licensee in their earlier submittals. The staff has, therefore, 1 determined that its earlier acceptance (December 30, 1982 SER) remains valid. I The staff, however, sought information relating to fire-induced high impedance l faults and electrical isolation deficiency concerns which can compromise '
safe shutdown capability, since these were not explicitly addressed in the reevaluation. The staff also requested additional information on the ICMs required to ensure safe shutdown capability in the interim period. By letters dated December 30, 1986, January 12, 1987, March 13, 1987, July 15, 1987, September 30, 1987, October 1,1987, October 9,1987, and November 20, 1987, the licensee provided their responses. In the these submittals, the licensee proposed some manual operations including hot shutdown repairs to eliminate fire-induced electrical isolation deficiencies, spurious operations and high
' impedance faults. Also, the licensee requested exemptions from the Appendix R,Section III.G.1 requirement for performing repairs for achieving and maintaining hot shutdown, in so far as it is interpreted as disallowing such repairs. In the March 13, 1987 submittal, the licensee further stated that since all the needed safe shutdown hardware modifications had been completed, their corresponding ICMs would not be needed. Also, by the July 17, 1987 submittal, the licensee identified a few differences relating to the plant safe shutdown configuration as it exists now from what has been described in the earlier SER (December 30,1982). For the reasons stated above, this SER addresses only differences from the earlier SER and the licensee's reevaluation relating to fire-induced electrical deficiency concerns, spurious operations concerns and high impedance faults concerns. Another SER, to be provided at a later date, will address technical exemptions requested in the reevaluation report related to fire protection features for specific plant areas, w
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l 2.0 EVALUATION 2.1 Spurious Operations and High Impedance Faults l In their submittals, the licensee stated that a fire in any one of certain I
plant areas could damage RHR system logic cables associated with safe shutdown equipment which, in turn, could result in spurious operations of RHR pumps and valves, diesel generators auxiliary equipment, safety relief valves (SRVs) and 4 kv breakers. Additionally, a fire event in any one of ,
certain plant areas could damage the circuits for SRVs resulting in their ;
spurious operations. To eliminate these spurious operations, the licensee i has proposed to deenergize applicable circuits by opening respective breakers at de distribution panels located in Fire Areas (FA) TB-I and TB-III-(TurbineBuildingNorthernandSouthernZoneGroups). For a fire, in either FA TB-1 or TB-III, the licensee has proposed to deenergize these circuits by pulling out control power fuses located in the applicable two of four panels in a timely manner (8 fuses within 30 minutes after scram for handling the RHR logic circuit concern and 10 fuses within 10 minutes after scram for handling the SRVs concern). All four panels, of which two of the panels (one for each unit) contain 8 fuses each and the other two panels (one for each unit) contain 10 fuses each, are !
located outside FAs TB-I and TB-III and are easily accessible following !
a fire event in either FA TB-I or TB-III. !
Regarding fire-induced high impedance faults (faults in circuits supplying power to non-safe shutdown loads from a common power source that supplies power also to safe shutdown loads) which can affect power supply to safe shutdown loads, the licensee stated that plant safe shutdown procedures require the operator to shed all non-safe shutdown i loads from common power buses by tripping manually the associated breakers in a timely manner. Additionally, these procedures require pulling out the 124 Y de control power fuses for electrically operated breakers associated with non-safe shutdown loads that are supplied power by 480 V or 4 kv switchgear common buses. This task will be performed prior to tripping applicable breakers as a precaution against their possible spurious closures. The licensee pointed out that such fuse pulling would be perforned either within 30 minutes or 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after scram depending upon whether such actions are required before initiating reactor water l makeup (30 minutes) or suppression pool cooling (3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />). ;
With regard to the fuse pulling operations mentioned above, the licensee stated that applicable control power fuses are easily identifiable, readily accessible, easy to remove, under periodic surveillance, and that i their removal would not involve any significant operator hazard. The licensee further stated that the plant shutdown procedures include operator instructions to perform the above tasks in a timely manner. '
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l Based on the above, the staff finds the licensee's proposed manual actions, i.e., tripping the applicable breakers and pulling out the applicable fuses in a timely manner for handling spurious operation and high impedance fault concerns, to be acceptable. The staff further recommends that the licensee's request for exemptions from the Appendix R,Section III.G.1 requirement for perforring the above mentioned hot shutdown repair, i.e., fuse pulling for achieving and maintaining hot shutdown, be granted.
2.2 Electrical Isolation Deficiency Regarding the fire-induced electrical isolation deficiency (i.e., a fault i on a remote circuit blowing a fuse common to both local and remote control '
circuits, prior to isolation of the netded hot shutdown circuit), that can compromise the ability to transfer the needed hot shutdown circuit to ;
local control, the licensee has identified seven cables as vulnerable to i this design problem. This is because these cables which are part of the 125V ,
de control circuitry for four breakers at the 480V buses, are singely l
- fused. The licensee stated that, in the event the common control power i fuses associated with these breakers are fire damaged and additionally these breakers are found open (two of these breakers are normally closed ,
and may not require any manual action), the plant shutdown procedures !
will require them to be manually closed in a timely manner (30 minutes) i i
using a jacking handle located in a cabinet in the vicinity of the '
applicable 480V switchgears. The licensee further stated that the maximum number of breakers that may require such manual closing at any one time due to a fire event is three. Besides the above, the licensee has identified three other control circuits, associated with engine starting controls for the Unit 1. Unit 2 and swing diesel generators, as vulnerable to electrical isolation deficiencies. The licensee stated .
that, for these circuits, all applicable blown fuses would be replaced in I a timely manner (within 30 minutes) and no more than two blown fuses, at any one time, would require such replacement. The licensee has committed to maintain replacement fuses and fuse pullers under surveillance in proximity of the engine starting controls for the diesel generators, and provide emergency lighting and needed man power in these areas to facilitate fuse replacements in a timely manner. The licensee further claimed that the circuits involved are low voltage control circuits and the fuses, though rated at 15 amperes, will actually carry much less current. Therefore fuse replacement will not pose any undue operator hazard. Based on the above, the staff has determined the licensee's proposed manual closing)of (i.e., fuse replacement applicable meet the breakers intent and and purpose of hot shutdown repairs, IE Information Notice No. 85-09, " Isolation Transfer Switches and Post-Fire Shutdown Capability", dated January 31, 1985, and are, therefore, acceptable. The staff further recommends that the licensee's request for exemption from .
Appendix R,Section III.G.1 requirement for performing aforementioned hot shutdown repairs (i.e., fuse replacement) for acheiving and maintaining i
hot shutdown, be granted.
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i 2.3 Differences with December 30, 1982 SER In the July 17, 1987 submittel, the licensee identified the differences in the safe shutdown configuration as it exists now at the plant from -
what has been described in the earlier SER dated December 30, 1982. !
The licensee additionally provided supporting justification for these H differences in the above submittal end other submittals referred to in I this SER. These differences are listed below: i
- 1. Backup water supply source for the safe shutdown makeup pump will be provided by the Fire Water System (FWS) instead of the Service Water System as originally indicated in the earlier SER Section 3.1.2.
Based on their hydraulic evaluation on the adequacy of the FWS, the licensee has concluded that the system can simultaneously meet the maximum fire oemand and supply cooling water to the safe shutdown makeup pump room cooler, and also provide backup water supply source for the safe shutdown makeup pump at later times when needed.
- 2. RHR flow indication instrumentation included as being available during a fire event, in Section 3.1.5 of the earlier SER, is not considered as riecessary diagnostic instrumentation. However, during torus cooling, the needed diagnostic instrumentation will be provided by suppression pool temperature indication and RHR pump discharge pressure indication.
- 3. Earlier SER Section 3.3 indicated there will be no need for hot or cold shutdown repairs for achieving and maintaining safe shutdown.
However, as indicated in Sections 2.1 and 2.2 of this SER, there may be hot shutdown repairs (i.e., fuse pulling and/or fuse replacement) depending upon the fire event. Cold shutdown repairs may also be needed for certain fire events (these are described in Section 2.4 of the licensee's December 18, 1984 submittal).
- 4. The plant does not have documentation for breaker / fuse coordination i for all instrumentation and power circuits as implied in the earlier SER Section 3.4.1. However, plant safe shutdown procedures include operator instructions for shedding non-safe shutdown loads from common power sources, and for fuse pulling when needed to handle high impedance faults associated with certain common power sources.
These insure all the safe shutdown loads in a given bus are free of fire induced faults whenever the bus is utilized to power safe shutdown loads.
Based on the above, the staff has determined there is reasonable assurance these differences will not compromise the safe shutdown capability of the plant and are, therefore, acceptable.
3.0 CONCLUSION
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The staff coscludes that the licensee's proposed approaches for resolving the fire-induced concer:is (i.e., spurious operations identified in this SER, high impedance faults, and electrical isolation deficiency) are acceptable. Consequently, the staff recommends that the licensee's exemption requests to allow conducting aforementioned hot shutdown repairs (i.e., fuse pulling and/or fuse replacement), for achieving and niaintaining hot shutdown, be granted. Futhermore, the staff concludes that the differences between the present safe shutdown configuration at the plant from what has been described in the December 30, 1982 SER, with regard to those items listed in Section 2.3 of this SER, are acceptable.
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