IR 05000424/1988016

Insp Rept 50-424/88-16 on 880307-10.No Violations or Deviations Noted.Major Areas Inspected:Areas of Safe Shutdown of Facility W/Limited Staff in Event of Main Control Room Fire & Equipment Actuations

ML20151P540
Person / Time
Site:	Vogtle
Issue date:	04/14/1988
From:	Hunt M, Mark Miller, Rogge J, Ruff A, Taylor P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20151P533	List: IR 05000424/1988016 ML20151P528
References
50-424-88-16, GL-86-10, NUDOCS 8804260190
Download: ML20151P540 (9)

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044 UN17ED STATES

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Report No.: 50-424/88-16 -i Licensee: Georgia Power Company P. O. Box 4545 Atlanta, GA 30302 Docket No.: 50-424 License No.: NPF-68 Facility Name: Vogtle 1 Inspection Conducted: March 7-10, 1988 Inspectors: h1 [h b . b 4//2/97 E D. Hunt

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Date Signed i 0. N A) V-/2 - FY Date Signed A. B. Ruff ~ if /  ;

h 62 s.s b 4. / - 92 Date igned P. A. TayTor 1U. Awkr lo J. F, Rogge [

klee Date Signed ItsML. #A~

M. N. Miller '/

'th.2) et Dat'e Signed

Accompanying Personnel

T. E. Conlon Approved by:

T. E. Conlon, Chief Date Signed Plant Systems Section i Division of Reactor Safety  !

- l SUMMARY Scope

This special, announced inspection was in the areas of safe shutdown i of the Unit I with limited staff in the event of a main control room fire and equipment actuations due to fire induced spurious sigrals.

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I Results: No violations or deviations were identified.

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8804260190 880415 PDR ADOCK 05000424

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REPORT DETAILS Persons Contacted Licensee Employees

• G. Bockhold, General Manager

• C. L. Christiansen, Shift Supervisor

• T. Green, Plant Support Manager

• C. Hayes, Vogtle QA Manager

• F. Kitchens, Operations Manager

• Kosinsky, Human Performance and Evaluation

• S. Lee, Operations Supervisor

• C. March, Deputy Operations Manager

• L. Mosbaugh, Assistant Plant Support Manager

• E. Swartzwelder, Nuclear Safety and Compliance Manager Other licensee employees contacted included construction craftsmen, engineers, technicians, operators, mechanics, security force members, and office personne Other Organizations

• P. Chandrs, . Electrical Engineer, Bechtel Power Corporation (BPC)

• C C. Foster, Mechanical Engineer, BCP

• Larson, Fire Protection Group, BCP

• P., L. George, Plant Engineering Supervisor, Southern Company Services (SCS)

• J. N. McLeod, Nuclear Safety Staff, SCS NRC Resident Inspm tors

• J. F. Rogge

• C. W. Burger

• Attended exit interview Exit Interview The inspection scope and findings were summarized on March 10, 1988, with those persons indicated in paragraph 1 above. The inspector described the areas inspected and discussed in detail the inspection finding No dissenting comments were received from the license The following new items were identified during this inspection:

Unresolved Item 50-424/88-16-01, Review Single Mode Failure for Volume Control Tank Outlet Valve . _ _ . _ . _

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The licensee did identify some materials as proprietary during this inspection, but this material is not included in this inspection repor . Licensee Action on Previous Enforcement Matters This subject was not addressed in the inspectio . Unresolved Items One unresolved item identified during this inspection is discussed in Paragraph . General Requirements This inspection was conducted to review the licensee's response to concerns raised during a QA team inspection (Inspection Report No. 50-424/87-69) and a fire protection inspection (Inspection Report N /87-71) conducted in the latter part of 1987. During these inspections it was found that the licensee, in the event of a main control room fire with fire induced spurious operations of equipment and a limited staff available, proposed to bring the unit to a hot shutdown mode from the remote operating panel with three licensed operators. This proposed arrangement appeared to conflict with the accepted operating procedures incorporated at other similar size nuclear plant This inspection consisted of an evaluation of: The licensee's design features to insure isolation of electrical circuits from a main control fire induced spurious signals (hot shorts, shorts to ground and/or open circuits.) Review of the abnormal operating procedures for operation from the remote shutdown panels and observations of a walkdown of operator actions required for a scenario with an all consuming main control room fire with only three operators availabl Review of Spurious Signal Isolation Features Nuclear power plants are designed and erected to provide for redundancy of electrical circuits and equipment to provide assurance that a single failure will not prevent safe shutdown of the unit in the event of a design base acciden Electrical redundancy is accomplished by maintaining acceptable separation of electrical cables, equipment and circuits. However, the common point for all operations of the redundant equipment is the main contrcl room. For this reason it is obvious that an all consuming fire in the main control room which causes immediate evacuation of operating personnel and causes spurious operation of equipment required for safe shutdown of the unit would present the most difficult operational condition . , - - - . .

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The licensee is required to assess the potential impact of fire induced i spurious operation or ncn-operational ability of equipment in conjunction )

with a loss of Offsite Power (LOP) and provide the necessary protaction of '

circuits and equipment, emergency / abnormal operating procedures, and adequately trained personnel to safely shut down the unit in the event of a control room fire as previously described. Electrical operation of equipment is accomplished at remote shutdown panels and other remote operating stations. Through electrical switching, control circuits required for safe shutdown functions are isolated from the main control room circuits such that fire induced sput ious signals or loss of power (blown fuses) will not effect operation of equipment needed to perform the shutdown function To assess the extent of spurious signals for a control room fire, 24 safe shutdown systems were evaluated by the licensee. These were evaluated on a component-by-component basis and included all cable / wires going in and out of the control for these system The inspectors selected two of these systems and several components in other systems to review plant-specific design factures, control circuits and the licensee's safe shutdown analy-i The two systems reviewed by the NRC inspectors were the redundant trains

' < the Class IE Diesel Generators. The Elementary Cabling Block Diagram sel Engine Generator DG1B (Train B) and DG 1A (Train A) Drawing Numbers

..JD-BH-G038 and were used for this review. All cables that were shown on these drawings that entered the control room were identified. The elementary wiring diagrams that showed these cable / wires for control and operation of the DG were reviewed for the effects of potential fire induced spuriou; signals. All were adequately analyzed by the licensee and were considered satisfactory. All the cabling and wiring in the control room for these systems can be isolated by the operation of the local / remote hand switches at the local stations. Although all this cabling / wiring was able to be isolated from the control room by operation of these switches, those circuits were not double fused as discussed in IEN 85-09, Isolation Transfer Switches and Pos t-Fire Shutdown Capabilitie This condition was identified by the licensee's A/E in letters of February 16, 1988 and March 1,1988, File No. X4BJ01 and X4AK01 and corrective action is being initiate The electrical circuits and licensee's analysis for the following l

components were also reviewed and determined to be satisfactor The circuits were isolable from the control room and local station circuits

were fused independent of the control room circuit HV-04428 & A (125V DC Solenoid Valve) Reactor Coolant System Head l Vent Valves

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' HV-8095B & 80968 (125V DC Solenoid Valves) Head Vent Valves to letdown Heat Exchanger l

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• 4 LV-1120 (480V AC Motor Operated Valvt) Refueling Water Storage Tank Outlet Valve LV-1128 (480 VAC Motor Operated Valve) Volume Control Tank (VCT)

Outlet Valve PV-0455A and 0456A (125V DC Solenoid Valves) Pressurizer Over-Pressure Relief Valves (PORV)

It was noted that the pressurizer overpressure relief valves (PORV)

circuitry was double fused in the positive leg of the 125V Power source (for control room and alternate shutdown operation) but the circuitry had a common 3 amp fuse in the negative leg of the 125V D.C. power source. During a cor, trol room fire, the 3 amp fuse could blow before it is isolated (from the control room) by operation of the transfer switch. However, if this occurred the valve would remain in its closed position or would fail in the closed position which is the desired position for accident mitigatio The licensee's A/E stated that the PORVs are not needed for the initial recovery stages and for long term operations the 3A fuse in that Auxiliary Building, if it had blown, could be replaced so that the PORVs could be operated at the alternate shutdown statio The licensee agree to re-examine this condition to determine if additional action may be desirable, e.g., adding instruction for this fuse replacement in the damage control recovery procedures or a possible circuit modificatio The licensee's evaluation and findings regarding the effect of spurious closure of the VCT outlet valve (LV-01128 or LV-0112C)

revealed that damage could occur to the centrifugal charging pumps within ten sec when both pumps are started in the event of LO With this concern in mind the licensee had requested to be allowed to realign the centrifugal charging pump suction to the Refueling Water Storage Tank (RWST) before abandoning the main control roo In view of the fact that all licensees are evaluated on the basis of only tripping the reactor prior to control room abandonnent, this action was not considered as part of this inspectio During discussions with the licensee and NRR plant systems personnel it was determined that additional information regarding the length of time the centrifugal pumps can operate with the VCT outlet valves closed was neede This is identified as an Unresolved Itsn 50-424/

88-16-01, Review Single Failure Criteria for the VCT Outlet Valve . Alternative Shutdown Capability Operating Shift Personnel Ouring the irspection conducted December 8-11, 1987 (Inspection Report 50-424/87-71) concerns were raised as to whether sufficient control room operators would be available utilizing T/S "Minimum Shift Crew" l

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. 5 (six operators) to man the fire brigade and the Alternate Remote Shutdown Panels in the event of a control room fire, requiring evacuation and safe shutdown from the remote panel During Unit 1 Startup Test Program a shutdown demonstration from outside the control room was performed using A0P 18038-1, Operations from Remote Shutdown Panels. This procedure was performed using six operators and never has been implemented with less than this number of operator An enforcement conference was held February 10, 1988, to discuss the above concerns as well as other matters. The licensee's presentation indicated that a safe shutdown of the plant at remote shutdown panels could be accomplished with three operators, concurrent with manning the fire brigade team with the remaining minimum shift cre b. Licensee Evaluation - Three Operators During December 1987 the licensee walked down A0P 18038-1, Revision 4, Operation from Remote Shutdown Panels. Measured times for local operators actions to perform the steps of the procedure were simulated and recorded. In addition operators travel times from the control room to the remote shutdown panels, adjacent 4160 volt switchgear rooms and the diesel generator buildings were measured and recorde Utilizing the travel times plus the times to perform the procedure steps the licensee conducted two scenarios using three operators at the plant simulator. One scenario assumed a control room fire and evacuation with a concurrent Loss of Offsite Power (LOOP), and multiple spurious component actuation The diesel generators and turbine driven auxiliary feed water pump were assumed to have automatically started on a LOO The second scenario was the same except no LOOP nor spurious component actuations. The scenarios were terminated when stable control of the plant parameters were achieve During both scenarios cooldown of the reactor coolant system caused a safety injection to occur. The licensee concluded from the scenario and simulator data that three operators were able to stabilize the plant and effect a safe shutdown without challenging any critical safety functions, Review /Walkthrough A0P-18038-1 Three Operators (1) Remote Shutdown Panels Two shutdown panels are provided. Train A panel is located adjacent to Train A 4160 volt switchgear room on Level A of the control buildin Train B panel is located on level A of the

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control building adjacent to the lower cable spreading room and is in close proximity to Train A panel . Both panels are immediately below the control roo Panel C contains the necessary control to operate the turbine

driven auxiliary feedwater . pum This panel is located at ground level in the auxiliary feedwater buildin Unit 1 diesel generators and local control panels are located at ground level in the diesel generator buildin (2) Scenario and Walkthrough - A0P 180381-1, Rev. 4 The inspectors reviewed the licensee's December 1987 evaluation of alternative shutdown capability from outside the control room using three operators which was performed at the plant'

simulator. Based on these reviews it was determine that a walkthrough of A0P-18038-1, Rev. 4, simulating procedure steps, using communications would be necessary in order to make a reasonable assessment of the three operator's capability to bring the plant to a stable Hot Standby condition. In addition a scenario which is in keeping with Generic Letter 86-10, dated April 24, 1986, yet would require operator actions at all remote shutdowa panels, local operations and also a manual start of the diesel generator to restore electrical power would have to be prescribe The following scenario and conditions for the walkthrough of the procedure were identified:

Scenario:

- Fire in the control rcom areas and evacuation is required

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Loss of Offsite Power

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Diesel generators did not start automatically and requires local starting of B D/G onl No safety injection occurred

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Multiple spurious events are inprogress

- Turbine driven auxiliary feedwater pump is required to be placed into service locally at remote shutdown panel "C"

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Train B equipment would be used to achieve Hot Standby conditions

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0perators (3) shallistart the walkthro' ugh of A0P-18038-1 from the control room

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Briskly walking through A0P-18038'-l' is permitted'

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Simulation of procedure steps is_ required

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Stop watches were used to assess time lines to isolate spurious events, establish auxiliary feedwater, . restore -

e diesel generator to service'and establish RCS pressure and inventory control

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Communication with operators using the plant sound' powered phone system would be used f , The licensee reviewed the above scenario using the plant simulator, . travel times and simulated operator actions at -the remote shutdown panels as required by steps of the-procedure-and identified no challenges to any critical safety function .(3) Conclusions-The inspectors observed the walkthrough of A0P-18038-1, Rev. 4

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starting at. the control room and . subsequently at the remote shutdown and 0/G ~ panels. The time lines to accomplish primary and secondary boundary isolation,- restore pressure and inventory control to the _ steam generators and reactor coolant system appeared reasonable. The inspectors, therefore, concluded that for the given scenario and three knowledgeable and well. trained operators it' would be feasible. to place the- plant in a hot standby condition at the remote shutdown panel Subsequent discussions with license management. indicated that

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' their intentions are to provide a normal . number of operators (five) for conduct of A0P-18038- Present administrative controls requires a shift operation crew of"10-11 operator The inspectors consider using only three operators an emergency t accommodation in terms of performing A0P-18038- s The inspectors identified the following items which the licensee is planning a revision to incorporate in to A0P-18038- An identifying note to ensure operators use same common jack for sound powered phone communications D -

Provid6 early transfer of 18B07 D/G control panel fans

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Reset control power to D/G panel after transfer, Attachment _

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- The licensee ' also indicated that the' scenarios and the

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- walkthrough of the procedure would be assembled and presented to-plant operators -in the "required reading" program. The lessons learned .and methodology for the walkthrough. of the procedure

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