ML20114B286
| ML20114B286 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 08/19/1992 |
| From: | Link B WISCONSIN ELECTRIC POWER CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| CON-NRC-92-095, CON-NRC-92-95 VPNPD-92-286, NUDOCS 9208250308 | |
| Download: ML20114B286 (7) | |
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' Electnc POWER COMPANY 231 W M:ctagon. Po. Ekn 204a Mho30a VA SY/01 I41412212M5 VPNPD-92-286 NRC-92-095 August-19,11992
=Mr. A.
Bert Davis, Regional Administrator U.
S.
NUCLEAR REGULATORY COMMISSION Region III-
-799 Roosevelt Road-Glen.Ellyn, Illinois 60137
Dear Mr. Davis:
DOCKET'50-251 l,
REOUEST FOR REGIONAL hAIVER OF COMPLIANCE L
_QPERABILITY OF REACTOR PROTECTION AND ENGINEERED SAFEGUARDS INSTRUMENTATION
- DURING 2LERISMIC EVENT-POINT-BEACH NUCLEAR PLANT,~ UNIT 1 The~ purpose of this letter is to document the basis for the request from: Wisconsin Electric Power Company for a Regional Waiver of Compliance from-the requirements-in Point Beach Nuclear Plant Technical Specification ie' tion-15.3.0, " Limiting Conditions For Operation, General Consiuerations," and Section 15.3.5,
" Instrumentation System," for a duration of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
A 72-hour
' waiver will provide'the time necessary to restore'the instrumentation cabinets containing Reactor-Protection System, Engineered Safeguards-System,-and process instrumentation for Point Beach Nuclear Plant -Unit'1,-to their design basis for seismic
- events.--
REOUIREMENT FOR WHICH THE WAIVER IS REOUESTED PBNP Technical 1 Specification Section 15.3.5 defines the operability requirements for Reactor Protection, Engineered Safeguards, and
= process:Instrrmentation'for the Point Beach Nuclear Plant units.
.This section defines minimum operable channels required -and -minihtum degree of' redundancy required.for this instrumentation.
These Llimits. ensure that safety 1s-not compromised by operation with
.certain instrumentation channels out of service.
The specification outlines limiting conditions lfor operation necessary,to. preserve the effectiveness of the Reactor Protection' System and Engineered Safeguards System when any one or more of-the channels is out of service..
. Specification 15.3.0, the general considerations for Technical Specification--Section 15.3, " Limiting Conditions for Operation,"
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Bert Davis August 19, 1992 i
Page 2 requires an affected unit which is critical to be placed in the hot i
shutdown condition within three hours if the conditions prescribed by the Limiting Conditions for Operation (LCO) cannot be satisfied.
Additionatly, if the conditions which prompted the shutdown cannot be corrected and the LCO does not specify an additional time period, i
the unit shall be placed into the cold shutdown condition within i
48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.
Th( uasis for these general considerations is to delineate action to be taken for circumstances not directly provided for_in the action statements of the specific LCO, the occurrence of which would violate the intent of the specification, oon August 18, 1992, the seismic mounting of instrumentation cabinets in the control room for Unit I was determined to be inadequate, such that it would_likely fail during a design basis seismic event.
This condition necessitated declaring the Reactor Protection System, Engineered Safeguards System, and process instrumentation contained in the affected cabinets inoperable which invokes the requirements of Technical Specification Section 15.3.0.
This requires placing Unit 1 in hot shutdown within three hours and in cold shutdcwn within the 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> if the condition cannot be corrected in the specified times.
CIRCUMSTANCES - SURROUNDING THE SITUATION During system and component reviews for upgrading of our Auxiliary Feedwater System 1to safety-related, the as-built base mountings of control room cabinets 1C-105 through 1C-135 were field reviewed using the. Seismic Qualification User's Group (SQUG) Ger.eric Implementation Procedure for Verification of Nuclear Platt Equipment and were determined to require' evaluation for seismic adequacy.
These cabinets contain Reactor Protection System, Engineered Safeguards System, and process instrumentation for Unit 1.
The cabincts are arranged such that 1C-105_through 1C-114 form one continuous integral row of cabinets and cabinets 1C-115 through 1C-135 form a separate row.
The cabinet rows are parallel to each other and are located on_the Unit 1 (south) side of the control room.
Adjacent cabinets are fastened together with bolting along the front and back vertical frame members.
The base of each cabinet consists of a four-inch channel frame.
Field tm i.ew indicated the cabinets were. anchored to the control room floor by friction clips positioned.at several locations along the bottom of the cabinet channel frame.
Each friction clip assembly consisted of 1/4-inch x 1-1/2 inch x 5-1/4 inch' plate steel with a 3/8-inch expansion anchor bolt attached to the floor.
Following the field review, the as-built configuration of cabinet row 1C-105 through 1C-114 was analyzed'to determine the seismic adequacy of the cabinet base mounting.
This cabinet row was anchored using three riction clips on the north side of the base
i A.
Bert Davis August 19, 1992 Page 3 and four clips on the south side.
CIr analysis was completed and verified on August 18, 1992 at 5:05 p.m.
We determined the base mounting was not seismically adequate in that the friction clips could be overloaded due to a postulated safe-shutdown earthquaxe.
Specifically, the plate steel clips wnre identified as the weak member and were loaded beyond their yield point by approximately a j
factor of three.
We have conoidered performing a non-linear plastic analysis of the friction clips, but due to the magnitude of the loading, we have judged that this analysis would not verify seismic adequacy.
Although we have not completed a specific analysis for the adjacent row of cabinets, 1C-115 through IC-135, it is our judgment that this row of cabinets la in the same condition as the analyzed row due to similar mounting configurations.
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We have field verified the Unit 2 instrumentation cabinet mountings on the north side of the control room and have determined that these cabinets have adequate mounting for seismic loading.
COMPENSATORY AND CORkECTIVE ACTIONE i
We have taken, or will take, the followinq compensatory and corrective actions:
1.
In order to complete a modification to the base mounting for cabinets 1C-in5 through 1C-135 in as timely a manner as possible, engineering personnel were mobil.ized late yesterday afternoon.
The engineering personnel have completed a design modification for adequate seicmic anchorage of ti.
cabinets.
The' design was completed _this morning and involves securing the front and back cabinet base channels using 3 inch x 4 inch 4
L x 3/8 inch angle steel fastened to the outsidc of the base thannels with 1/2 inch bolts and anchored to the floor with 5/8 inch x 7_ inch concrete expansion anchors.
Installation of the modification began this afternoon.
Following installation af this modification, the cabinet mounting will meet design basis requirements and the instrumentation contained in the cabinets.will be declared operable.
l-L 2.
_ We will not remove any Reactor Protection System or Engineered Safeguards Feature systems or associated components from service until the instrumentation is restored to its design basis conditions.
During our telephone conference on' August 18,-1992, we informed you-that one service water pump was out of service for maintenance.
Subsequent to our telephone L
conference, at~approximately 4:00 p.t. -today, a second service l
water pump was removed from service due to a suspected L
electrical motor fault.
Neither of these occurrences has any L
impact on the need for this waiver from our license conditions.
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-A..Bert Davis August-?C, 1992 Page 4 3.
We have requested special consideration from our System Control Center to minimize requests for changes in loading of the Point Beach units.
4.
Work on the alternate shutdown system, or any work which could affect the operability of the alternate shutdown system, has been prohibited for the duration of the waiver.
SAFETY SIGNIFICANCE AND POTENTIAL CONSEOUENCES-A seismic event is not considered an initiator for any design basis accident analysis presented in the PBNP Final Safety Analysis Report, Chapter 14, " Safety Analyses."
The Reactor Protection and Engineered Safeguards instrumentation and equipment remain operable for all conditions other.than a seismic event.
The design basis safe shutdown earthquake (SSE) for Point Beach assumes a h'orizontal ground acceleration of 0.12g.
At the SSE acceleration, calculations show that some components of the cabinet mountings are overloaded by approximately a factor af three.
- Thus, in general, these components should withstand a horizontal ground acceleration on the order of one third the SSE level, or 0.04g.
The annual met n probability of exceeding a peak ground acceleration of 0.04g at the Point Beach site is on the order of 1E-03 per year.
This estimate _is obtained from EPRI Report NP-6395-D, "Probabilistic Seismic Hazard Evaluations at Nuclear Plant Sites in the Central and Eastern United States: Resolution of-the Charleston Earthquake Issue," dated April 1989.
This report was developed by EPRI.and_the Seismicity owners Group (SOG) using a seismic hazard methodology described in a generic topical report submitted to the
.NRC_in-July 1986 (Technical Report NP-4726-A, EPRI, July 1986).
On the basis of this annual seismic event fregaency, we estimate that-the probability of a seismic event equivalent to or exceeding one third of our SSE eccurring during the requested duration of this waiver 1(72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />) is approximately 8E-06.
This_ represents an extremely small probability of these analog instrument cabinets and the contained instrumentation becoming inoperable due to a seismic i
event within'the 72-hour time period.
As discussed with you during our telephone conference on August 18,
.given a failure'of these cabinets and associated instrumentation to perform.their safety functions,. manual initiation of Reactor Protection System and Engineered Safeguards Features functions would remain available.
'Also, Point Beach-has the capability to safely shut.down the plant and maintain the plant in a safe shutdown condition using remote shutdown panels.
This capability was p
installed for resolution of Appendix R safe shutdown requirements.
l Switches at the shutdown-panels are used to isolate the instrument l
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A.-Bert Davis August 19,-1992 Page 5
-indication at the panels from the control room instrumentation.
Therefore, loss of the instrumentation in the control room will-have no effect on our ability to place and maintain the plant in a safe shutdown condition.
JUSTIFICATION FOR THE DURATION OF THE WAIVEB The requested 72-hour waiver period will be sufficient to allow us to complete the design and installation of modifications to instrument cabinet supports, restoring their capability to withstand the design basis seismic event.
This work is expected to take approximately 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. - However, 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is requested to allow for any unanticipated delays in the design, procurement of materials, L
and installation process.
If problems are encountered during the installation such that a unit trip or significant effect on unit operation is likely, the unit will be placed in hot shutdown prior l
to continuing with the installation.
l Based on the low probability of a seismic event during the waiver period and the capability to place and ma!.ntain the plant in a safe condition following a failureuof the instrumenc cabinets, we have concluded that the duration we have requested for this waiver of compliance is justified and appropriate.
I SIGNIFICANT HAZARDS CONSIDERATION We have evaluated the continued operation of Unit 1 with non-seismically qualified instrument cabinets containing Reactor Protection-System and Engineered Safeguards System instrumentation for the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> requested in this waiver, in accordance with the standards contained in 10 CFR 50.92, " Issuance of amendment," and have determined that the continued operation of Unit i during this-time period does not result in a significant hazards consideration.
l Operation of a facility in accordance with a temporary waiver of l.
compliance involves no significant hazards if it_does not:
1.
Involve a significant increase in the probability or consequences of an accident previously evaluated; or L
2..
Create the possibility of a new or different kind of accident from any accident previously evaluated; or 3.
Involve a significant reduction in a margin of safety.
The Reactor Protection System, Engineered Safeguards System, and process instrumentation in the affected #
strument racks were declared' inoperable due to the cabinets containing the instruments being inadequately mounted to withstand the SSE for PBNP.
The instruments remain operable and functioning for all operating
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Bert Davic August 19, 1992 Page 6 conditions other than a seismic event.
The PBNP design basis does not consider a seismic event an initiator of any of the design basis accidents in the PBNP Final Safety Analysis Report Chapter 14,
" Safety Aaalyses."
All reactor protection and engineered safeguards systems remain capable of performing their fur.: tion as analyzed in the safety analyses.
Therefore, under normal operating conditions, an increase in the probability or consequences of an accident previously evaluated will not occtc, the possibility of a new or different kind of accident other than any accident previously evaluated is not created, and a reduction in margin of safety cannot occur.
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PBNP is designed to continue operating or to be brought to a safe shutdown condition dependent on the magnitude of a seismic event.
A seismic event will not result in the initiation of a separate design basis accident.. If a seismic event should occur during the 72-hour period requested in this waiver, the operability of reactor protection and engineered safeguards equipment cannot be assured.
However, indications and manual operations at alternate shutdown panels will be utilized to bring Unit 1 to a safe shutdown condition.
Alternate shutdown panels are installed at locations remote from the control room with indications and controls for
-necessary systems and components to bring the unit to a safe shutdown condition.
Manual switching provides remote indication at these panels and completely separates them from the control room L
instrumentation.
Therefore, failure of the instrumentation in the control room cabinets will not affect the indication at the remote shutdown panels and will not provent the remote and/or manual control of systems and components necessary for achieving and maintaining a safe shutdown condition.
Thus, an increase in the probability or consequences of an accident previously evaluated will not-occur, the possibility of a different kind of accident than any-previously evaluated is not created, and the margin of safety is l
'not reduced.
i-ENVIRONhENTAL CONSEOUENCES Operation of Unit I under the conditions of this temporary waiver
- from our license requirements does not result in changes to the installation or use of the facilities or components as described in 10 CFR 20, " Standards For Protection Against Radiation."
Increases
-or changes in the types of effluents that may be released off site will not occur, nor will there be an increase in individual or cumulative occupational radiation exposure.
Operation of the unit during the requested waiver period results in no significant hazards.
Therefore, this request satisfies the categorical exclusion requirements of 10 CFR 51.22 (c) (9).
An environmental assessment or environmental impact statement is not required.
f f.1 A:'Bert Davis August 19,-1992 Page 7 STATE NOTIFICATION The appropriate staff member of the Public Service Commission of Wisconsin (PSCW) will be provided with a copy of this applicatinn in
-accordance with 10 CFR 50.91 (b).
SUMMARY
OF EVALUATIONS AND COMMUNICATIONS The PBNP Manager's Supervisory Staff (MSS) discussed this issue at approximately 2:00 p.m. on-August 18, 1992, and concurred in the decision to request this waiver pending final review and verification of the calculation showing nonconformance of the instrument cabinets with their denign basis.
The MSS was informed of the-review and verification of the calculation at approximately 5:05 p.m. on August 18, 1992.
The MSS declared the instrumentation L
inoperable at that. time.
An informational notification was made to the NRC Operations Duty Officer based on the preliminary calculations at 4:03 p.m. on August.18, 1992.
Following declaring the instrumentation inoperable-a one-hour-notification was made in accordance with 10 CFR 50.72 (b) (1) (1) - (a), and completed at 5:57 p.m.
An informational notification was also made to NRR and Region III staff at approximately 4:05 p.m. to discuss the discovered condition and likely need for a regional waiver from license requirements.
WS will continue to conform to all other license requirements during the period of the authorized waiver.
If repairs cannot be completed within the 72-hour period and.an additional waiver is not authorized by your office, we will place Unit 1 in a hot shutdown condition within three hours and a cold shutdown condition within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.
We received verbal approval of this request for waiver from your offices during our telephone conference with Messrs. Edward Greenman, John Zwolinski, and other members of Region III and NRR staff at 6:05 p.m. on August 18, 1992.
This approval was contingent
-upon the submittal of this request and completion of the compensatory-and corrective actions described above.
Please-contact us if you have any additional questions or require additional'information concerning this-request.
Sin,erely
~ f /J 24EG Bob Link Vice President Nuclear Power l
Copies to NRC Document Control Desk l
NRC hesident Inspector Assistant Director for R aactor Projects, NRR Public Service Corumission of Wisconsin
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