NG-94-4017, Provides Info Requested in NRC on 17 Valves That Util Intends to Remove from GL 89-10 Program

Provides Info Requested in NRC on 17 Valves That Util Intends to Remove from GL 89-10 Program

ML20077D325
Person / Time
Site:	Duane Arnold
Issue date:	11/30/1994
From:	Franz J IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT
To:	Russell W NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
GL-89-10, NG-94-4017, NUDOCS 9412080202
Download: ML20077D325 (13)

Text

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. UTILITIES INC.

John F. Franz. Jr.

Vice President, Nuclear November 30,1994 NG-94-4017 hir. William T. Russell, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Attn: Document Control Desk hiail Station Pl-137 Washington, DC 20555

Subject:

Duane Arnold Energy Center Docket No: 50-331 Op. License No: DPR-49 Generic Letter 89-10 Program

Reference:

Letter T. lisia to IES Utilities Inc. dated October 12,1994, " Summary of hieeting held on September 22,1994, Extension of Generic Letter 89-10 Program Schedule at Duane Arnold" File: A-10lb

Dear hir. Russell:

In the above referenced letter, your stafTrequested additional information from IES Utilities Inc. on the 17 valves that v e intend to remove from our Generic Letter (GL) 89-10 program. Specifically, your stafTrcquested that we supply a discussion of the function of the 17 hiotor Operated Valves (A10Vs)in question and the available and required stroke times for these valves. Information was also requested, if available, concerning the demonstration of the capability of the 17 h10Vs to operate based on present torque switch thrust settings, surveillance testing under flow and preventive maintenance performed.

The purpose of this letter is to provide the requested information. The attachment to this letter includes valve identification, description of the valve's function, required stroke time, available stroke time and current capability (expressed in percent above hiinimum Required Stem Thrust)-

Also included in the above reference was a request to provide additional examples of where administrative Allowed Outage Times ( AOTs) are used during surveillance testing on the systems of the valves in question On this issue, a point of clarific tion pnonto J UUU sJ

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l Mr. William T. Russell  ;

November 30,1994 l NG-94-4017 Page 2 of the meeting summary is needed. In the fourth paragraph on page 2 a statement was made that we use administrative AOTs for the purposes of conducting on-line maintenance. In fact, administrative AOTs are applied only during specific Technical Specification (TS) required surveillances and are not utilized during maintenance activities. This practice is in keeping with our overall efforts of minimizing safety ,

system unavailability.

l During the meeting on September 22, we gave an example of our use of administrative .

AOTs for the High Pressure Coolant injection (HPCI) system quarterly operability test. During a portion of that test, the system is taken out of automatic flow control and placed in Manual mode. It is during this segment of that test that the AOT is used. The 6-hour AOT was chosen based upon the analogous AOT for HPCI system automatic actuation instrumentation given in the TS tables for Emergency Core Cooling System (ECCS) instrumentation (Table 3.2-B)

In addition, during the annual Simulated Automatic Actuation (SAA) test of the ECCS (HPCI, Core Spray and LPCI mode of RHR) and RCIC, the injection valves to the reactor are disabled to prevent inadvertent injection during power operation.

Consequently, during the SAA testing, the affected system is not capable of automatically responding to an actual demand for injection. A 6-hour AOT is employed during these tests on the same basis as the HPCI AOT discussed during our meeting. This supplementary administrative control provides additional assurance that system unavailability is minimized.

Again, our philosophy and basis for not declaring systems inoperable for the purposes of entering Limiting Conditions for Operation (LCO) during TS-required testing is based upon the reliability analyses referenced in our TS BASES (APED-5736, Guidelines for Determining Safe Test Intervals and Repair Times for Engineered Safeguards) and referenced in our Updated Final Safety Analysis Report (NEDO-10739, Methods for Calculating Safe Test Intervals and Allowable Repair Times for Engineered Safeguard Systems). These analyses differentiate between system / component out-of-service time for repair, which determines the LCO time, and the out-of-service time due to periodic testing, which determines the surveillance frequency. While they are mathematically related to one another, they are distinct parts of the establishment of overall reliability and are not interchangeable. Therefore, to enter the LCO for the purposes of TS-required surveillances would be inconsistent with the basis of our TS.

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l Mr. William T. Russell November 30,1994 NG-94-4017 Page 3 i This letter contains no new commitments.

If you have any questions concerning the above, please contact my ofTice.

Sincerely, ,

1

' John F. Franz Vice President, Nuclear

Attachment:

1) Additional Valve Information cc: R. Murrell L Liu L. Root G. Kelly J. Martin (Region III)

NRC Resident inspector - DAEC DOCU

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Attachment to NG-94-4017 P. age 1 1 Additional Valve information .

1 Definitions: l Reouired Stroke Time (RST1- The maximum allowed stroke time per current accident analysis. The Required Stroke Time is based upon the longest component response time in the accident mitigation flow path, m, LPCI Injection Valve stroke time, such that the required overall system response time is not affected by the valve in question, assuming that we must postulate recovery from these secondary modes of operation. (Note: Does not assume loss-of-offsite power).

Available S1roke Time - Taken from GL 89-10 testing; the larger of the current open and close valve stroke times rounded to the next larger second.

MRST- Minimum Required Stem Thrust (As described in the schedule extension).

( Required Available Current Valve # Description Stroke Stroke Time Capability Time (Seconds) (% above (Seconds) MRST)

MO-1912 'B' RHR Shutdown Cooling Pump 30* 126 514 Suction Valve MO-1920 'B' RHR Shutdown Cooling Pump 30* 127 381 Suction Valve MO-2011 'A' RHR Shutdown Cooling Pump 30* 126 828 Suction Valve MO-2016 'A' RHR Shutdown Cooling Pump 30* 125 276 Suction Valve These valves must open to allow operation of the non-safety related Shutdown Cooling (SDC) mode of RHR. Recovery from SDC mode to LPCI mode is solely a manual process by the operator. The valves must remain closed to allow operation of the LPCI and post-LOCA containment heat removal modes of RHR.

To prevent draining the reactor vessel to the suppression pool, these valves are interlocked with the torus suction valves such that both suction paths can not be opened simultaneously. Thus, the available stroke time listed above is the sum of the individual stroke times for the SDC and Torus Suction Valves and does not include the additional time necessary for the operator to react and initiate the manual realignment.

Attachment to NG-94-4017 Page 2 NEDC-31890, Sec. 2.6.2, pg. 38, (for valve F2) states, "This normally closed valve is only open during reactor shutdown cooling. It allows the RHR pump to take suction from a recirculation line of the reactor for shutdown cooling. There is no safety related function for this valve because it remains closed for all safety-related operations. Therefore, this valve is exempt from GL 89-10 test recommendations for both opening and closing." The shutdown cooling mode of RHR is considered a non-safety-related mode of RHR (ref. sec, 2.6.1.1, pg. 36, of NEDC-31890). The referenced valves are normally closed and are depicted as being closed on the system drawings, and would not reposition from the position shown.

RST for RHR is based upon time for pumps to reach rated speed assuming off-site power is available. Thus, if we subtract the 20 sec. for Emergency Diesel Generator start time assumed in References 1 and 2, the pump start time dominates over the injection valve stroke time and dictates the overall response time. (Note: These are "new" LOCA analysis methods which use the SAFER /GESTR analysis methodology. "Old" methods were presented in the Sept.

22 meeting.) We have also assumed instantaneous vessel depressurization, such that there is no additional time delay for the injection valve permissive at 450 psig.

This was done to simplify this discussion.

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Attachment to NG-94-4017 Page 3 Required Available Current -

_ Valve # Description Stroke Stroke Time Capability Time - (Seconds) (% above (Seconds) MRST)

MO-1936 RHR Drain to Radwaste Valve 30' 5 79 MO-1937 RHR Drain to Radwaste Valve 30* 12 76 These valves are opened to allow draining of the torus or reactor to radwaste, which is a non-safety related function. They must remain closed to allow operation of LPCI or post-LOCA ccm linment heat removal. These valves are interlocked to close, if open, on a Group 2 or Group 4 Primary Containment isolation System signal, in order to prevent draining the RHR system to radwaste.

NEDC-31890, sec. 2.9.3, pg. 46, (for valve 13) states, "These two in-series normally closed valves open to provide a flow path to drain the reactor or suppression pool to the radwaste system. There is no safety-related function for these valves because they remain closed for all safety-related operations.

Therefore, these valves are exempt from GL 89-10 test recommendations for both opening and closing." The reactor / torus drain to radwaste mode of RHR is considered non-safety-related.

RST for RHR is based upon time for pumps to reach rated speed assuming off-site power is available. Thus, if we subtract the 20 sec. for Emergency Diesel Generator start time assumed in References 1 and 2, the pump start time dominates over the injection valve stroke time and dictates the overall response time. (Note: These are "new" LOCA analysis methods which use the SAFER /GESTR analysis methodology. "Old" methods were presented in the Sept.

22 meeting.) We have also assumed instantaneous vessel depressurization, such that there is no additional time delay for the injection valve permissive at 450 psig.

This was done to simplify this discussion. <

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Attachment to NG-94-4017 Page 4 Required Available Current Valve # Description Stroke Stroke Time Capability Time (Seconds) (% above (Seconds) MRST)

MO-1941 'A' RHR Heat Exchanger Outlet N/A *

• 60 22 Valve MO-2031 'B' RHR Heat Exchanger Outlet N/A *

• 57 16 '

Valve Per the RHR system operating instructions, the outlet valves must remain open to support post-LOCA containment heat removal and can not be throttled.

NEDC-31890, sec. 2.3.1, pg. 24, (for valve C1) states, "These normally opened valves are located at the inlet and outlet of the RHR heat exchanger and allow RHR pump flow through the heat exchangers before injection into the reactor or l containment. These valves remain open for all safety-related operations. In some plants, however, they are closed before initiation of the RHR pumps in the suppression pool cooling mode and then reopened after the pumps are running. ,

The outlet valve may also have a safety-related function to close before flooding the core with the RHR Service Water. On plants provided with steam condensing, they are closed during steam condensing." At the DAEC, the RHR steam condensing mode has been permanently disabled.

The post-LOCA containment heat removal function is a manual operator action which occurs later in the accident sequence. Therefore, there is no minimurn required stroke time in the accident analysis.

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, 1 Attachmont to NG-94-4017 Page 5 Required Available Current ,

Valve # Description Stroke Stroke Time ~ Capability I Time (Seconds) (% above ]

(Seconds) MRST) J MO-2010 RHR Cross-tie Valve 30' 88 33 )

l This valve must remain open during LPCI operation to ensure that the required l flow can be delivered to either recirculation loop. This valve may be closed (in j accordance with operating instructions) to allow splitting of the RHR loops, so that j one loop may be used for post-LOCA containment heat removal while the other l loop continues to deliver flow to the core. However, this operation is not relied I upon to mitigate the accident / transient.

NEDC-31890, sec. 2.5.1, pg. 35, (for valve E1, BWR/4 with Loop select logic) l states, "A single MOV is located on the line connecting loops A and B. This normally open valve could be closed to isolate one RHR loop from another. There is no safety-related function for this valve because it remains open for all safety- 1 related operations to allow all the RHR pumps to inject into either recirculation loop. BWR/3 plants require that three of the four pumps are running in order to .

develop rated LPCI flow, in the event of a recirculating line break, sensors detect which line is broken and prevent the inject valve (B1) on that line from opening ,

and signals the valve in the unbroken loop to open. The logic is referred to as l'

" loop selection logic". Since the cross-tie closure is not required during plant operation, the valve is key locked open during all safety-related operations.

Therefore, this valve is exempt from GL 89-10 test recommendations for both opening and closing." ,

RST for RHR is based upon time for pumps to reach rated speed assuming off-site power is available. Thus, if we subtract the 20 sec. for Ernergency Diesel Generator start time assumed in References 1 and 2, the pump start time dominates over the injection valve stroke time and dictates the overall response time. (Note: These are "new" LOCA analysis methods which use the t SAFER /GESTR analysis methodology. "Old" methods were presented in the Sept.

22 meeting.) We have also assumed instantaneous vessel depressurization, such  :

that there is no additional time delay for the injection valve permissive at 450 psig.

This was done to simplify this discussion.

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Attachment to NG-94-4017.

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Required Available Current Valve # - Description Stroke Stroke Time Capability Time (Seconds) (% above .

(Seconds) MRST) - l MO-2311 HPCI Pump Discharge Valve 45** 15 2.8 *

,MO-2511 RCIC Pump Discharge Valve N/A * *

• 11 20 These valves must remain open to allow HPCI and/or RCIC flow to be delivered to the reactor vessel.

NEDC-31322, sections 3.3.3.7 and 3.3.4.7, pg. 26 and 38 state, " Valve number 8 in figures 2 and 4 (figure 6) is normally open and functions as the systern injection valve test valve. It is only closed to perform operability testing of the system injection valve. During an abnormal event, it is required to remain open. Based on the BWR design basis assumptions in Sections 3.3.1.1 and 3.3.1.2, the valve is not required to perform an active safety function during FSAR design basis events.

Therefore, the valve has no active safety action / operation requirements. The i maximum differential pressure across this valve during plant normal operation occurs when the valve is re-opened following its closure so that the injection valve '

operability stroke test can be performed. Valve operation during injection valve testing demonstrates the capability of the valve to actuate against the differential pressure that occurs during plant normal operation. Therefore, testing to comply with Reference 1 is not rt.auired for the plant normal operating actuation of this valve."

Based on Actual DP Test Per Reference 2.

The RCIC system is not part of ECCS and has no minimum required stroke time in the accident analysis.

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NG-94-4017 Page 7 Required Available. Current Valve # Description Stroke Stroke Time Capability Time (Seconds) (% above  :

(Seconds) MRST)

MO-2316 HPCl/RCIC Test Return Redundant 45* 27 283 Shutoff Valve l MO-2515 RCIC Test Return Valve N/A " 14 Not Tested These valves must remain closed to ensure rated HPCl/RCIC flow is delivered to the reactor vessel. These valves may be opened during EOP operations to allow RPV pressure control, however, this operation is not relied upon to mitigate any design-basis accidents or transients. The valves may be opened to allow testing of the system; however, this testing function is not a safety related function.

NEDC-31322, sections 3.3.3.5 and 3.3.4.5, pages 25 and 37, states, " Valves number 5 and 6 in figures 2 and 4 (figures 6 and 7) are normally closed and function as the system CST test return shutoff valves. During an abnormal event, the valves are required to remain closed so that all system flow will be to the reactor vessel. Based on the BWR design basis assumptions in sections 3.3.1.1 and 3.3.1.2, the valves are not required to perform an active safety function during the FSAR design basis events. Therefore, these valves have no active safety action / operation requirements. These valves are open when the system is being tested to verify flow capability. Valve operation during the flow test demonstrates the capability of these valves to operate against the maximum differential pressures that occur dur!ng the test."

Per Reference 2. 1 The RCIC system is not part of ECCS and has no minimum required stroke time in the accident analysis.

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NG-94-4017

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Required . Available' Current Valve # Description Stroke Stroke Time Capability i Time (Seconds) (% above (Seconds) MRST)

MO-2112 'A' Core Spray Test Return Valve 18* 28 55 MO-2132 'B' Core Spray Test Return Valve 18* 24 103 The valves must remain closed to ensure that full Core Spray flow is delivered to the reactor vessel, and to ensure that primary containment integrity is maintained. [

They are opened to allow testing of the Core Spray system; however, this testing function is not safety-related.

NEDC-31871, sec. 2.3.3, pg. 29 and 30, states, " Valve C1 is normally closed and functions as the suppression pool test return isolation valve. During a FSAR >

design basis event, the valve is required to remain closed in order to (a) provide containment isolation, and (b) ensure that all system flow is directed to the reactor vessel, it is intended to be opened for system surveillance flow testing when the plant is in a normal condition. This valve is required to remain closed for all FSAR design basis events. Since the valve is normally closed and none of the FSAR design basis events result in opening of the valve, the valve has no active safety action / operation to open or close. (See general assumption 1.5.2). Therefore, testing to comply with the recommendations of GL 89-10 is not required for the plant normal operating actuation of this valve." ,

RST for RHR is based upon time for pumps to reach rated speed assuming off-site power is available. Thus, if we subtract the 20 sec. for Emergency Diesel Generator start time assumed in References 1 and 2, the pump start time dominates over the injection valve stroke time and dictates the overall response  ;

time. (Note: These are "new" LOCA analysis methods which use ths SAFER /GESTR analysis methodology. "Old" methods were presented in the Sept.

22 meeting.) We have also assumed instantaneous vessel depressurization, such  !

that there is no additional time delay for the injection valve permissive at 450 psig. l This was done to simplify this discussion.

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Attachment to NG-94-4017

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Required Available Current i Valve # Description Stroke Stroke Time ' Capability Time (Seconds)- (% above '

(Seconds)- MRST)

MO-2115 'A' Core Spray Outboard injection 18' 7 15 Valve i l

MO-2135 'B' Core Spray Outboard injection 18' 7 18 Valve These valves must remain open to ensure that full Core Spray flow is delivered to I the reactor vessel. They may be closed to allow testing of the inboard injection I valves, however, this function is not a safety related function. These valves are ,

not containment isolation valves.

NEDC-31871, sec. 2.3.2.2, pg. 29 states, "This normally open valve functions to allow testing of the CS injection valve (B1). The valve is closed to prevent over i pressurization of the upstream piping and components during operability testing of l the inboard valve (B1). After testing the inboard valve, the outboard valve is reopened. Its safety-related function is to remain open for all design basis events. l Therefore this valve has no active safety related function. This normally open l valve is required to remain open for all FSAR design basis events. Since this valve '

is normally open and none of the FSAR design basis events results in closure of the valve, the valve has no active safety action / operation to open or close. (See general assumption 1.5.2). Therefore, testing to the recommendations of GL 89-10 is not required for the plant normal operating actuation of this valve." l RST for RHR is based upon time for pumps to reach rated speed assuming ,

off-site power is available. Thus, if we subtract the 20 sec, for Emergency Diesel l Generator start time assumed in References 1 and 2, the pump start time j dominates over the injection valve stroke time and dictates the overall response time. (Note: These are "new" LOCA analysis methods which use the SAFER /GESTR analysis methodology. "Old" methods were presented in the Sept.

22 meeting.) W1 have also assumed instantaneous vessel depressurization, such that there is no additional time delay for the injection valve permissive at 450 psig.

This was done to simplify this discussion.

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i Attachent to NG-94-4017 Page 10

References:

1) NEDC-31310-P, Duane Arnold Enerav Center SAFER /GESTR-LOCA Loss-of-Coolant Accident Analysis, August,1988.

2) NEDC-31310-P, Supplement 1,Duane Arnold Enerav Center SAFER /GESTR-LOCA Loss-of-Coolant Accident Analvsis August,1993.

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