3F1297-21, Forwards Response to NRC Questions & Comments Re Rev 1 to LAR 220,removing Portion of OL Condition 2.C.(5) Re Installation & Testing of Flow Indicators in ECCS to Provide Indication of 40 Gallons Per Min for Boron Dilution

Forwards Response to NRC Questions & Comments Re Rev 1 to LAR 220,removing Portion of OL Condition 2.C.(5) Re Installation & Testing of Flow Indicators in ECCS to Provide Indication of 40 Gallons Per Min for Boron Dilution

ML20202D039
Person / Time
Site:	Crystal River
Issue date:	12/01/1997
From:	Holden J FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F1297-21, TAC-M99128, NUDOCS 9712040129
Download: ML20202D039 (8)

Text

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i Fl rida l

Power E?tTLW C.?a*E.".iu.m-n December 1,1997 3F1297-21 U.S. Nuclear Regulatory Commission l

Atta: Document Control Desk I

Washington, DC 20555-0001

Subject:

Clarification to License Amendment Request #220, Revision 1 (TAC No. 99128)

References:

1. FPC to NRC letter,3F1097-08, dated October 31,1997, " License Amendment Request #220, Revision 1, Revision of Operating License Condition 2.C.(5)"

2. FPC to NRC letier,3F1097-32, dated October 31,1997, " License Amendment Request #223, Revision 0, Post LOCA Boron Precipitation Prevention"

3. FPC to 11RC letter, 3F0897-24, dated August 4,1997, " Drop Line Valve Position 1.ndication" 4 NRC to Baxock & Wilcox Company letter, dated February 18, 1977, "Evaluauon of B AW-10103"

5. NRC to FPC letter, 3N1276-11. dated December 30,1976, " Issuance of Amendment No.1 ta Facility Operating License No. DPR-72 for Crystal River Unit 3 Nuclea*: Generating Plant"

Dear Sir:

Farida Power Corporation (FPC) is submitting this letter to respond to NRC questions and cocunents on License Amendment Request (LAR) #220, Revision 1 (Reference 1) and to clarify Q

that request. LAR #220 requests an amendment to Facility Operating License No. DPR-72 for E

Crystal River Unit 3 (CR-3) to remove that portion of Operating License Condition 2.C.(5) dealing with installation and testing of flow indicators in the Emergency Core Cooling System Gjs.

(ECCS) to provide an indication of 40 gallons per minute for boron dilution.

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This letter responds to NRC comments made during NRC/FPC meetings from November 3

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through 7,1997, at CR-3; in meetings at Framatome Technologies, Inc. (FTI) offices in Lynchburg, Virginia op November 18 and 19,1997; and in subsequent NRC/FPC telephone conversations on November 25 and 26,1997, to review LAR #220 and LAR #223 (Reference 2).

9712040129 971201

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PDR ADOCK 05000302 f

P PDR CRYSTAL RIVER ENERGY COMPLEX: 15760 W. Power Une Street

• C ystal River. Flonda 34428-6708 - (352) 795-6486 A Flanda Progress Company l

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O U.S. Nuclean Regulatory Commission l

3F1297-21 Page 2 of 4 In 1976, FPC, Babcock & Wilcox (B&W), and the NRC determined that the establishment of a requirement to measure a Dow rate of at least 40 gpm in either the Decay Heat (DH) System drop line dump-to-sump (DTS) or the Auxiliary Pressurizer Spray (APS) line would assure the conditions for boron precipitation mitigation were effective. The supponing analysis was described in the Babcock & Wilcox (B&W) Topical Report BAW-10103A, Revision 3, "ECCS Analysis of B&W's 177-FA Lowered-Loop NSS," that was appraved by the NRC in Reference

4. Based on the analyses in BAW-10103A, Revision 3, Operating License Condition 2.C.(5) was required by License Amendment No.1 (Reference 5).

Upon further analysis, FPC has determined that establishing a flow path only initiates boron dilution flow, while assurance that the flow path is effective would require a more direct measurement of boron dilution. A more direct measure of how well any post-LOCA boron mitigation path is working would be confirmed by the change in boron concentration in the Reactor Building (RB) Emergency Sump (WDSU-1), not merely the existence of flow in the DTS line or APS line. Therefore, LAR #220, Revision 1, proposes that the RB Emergency Sump boron concentration will be monitored to s erify that it is increasing, thus providing added assurance that boron would not be concentrating within the reactor vessel (RV).

The intent of Operating License Condition 2.C.(5) is met or functionally exceeded by confirming that the flow path is open using valve position indication, implementing the proposed boron concentration measurements, and using supporting analysis. For example, adequate APS flow is assured by alignment of the Low Pressure Injection (LPI) system and throttling of the LPI pump flow rates that ensure conformance with hydraulic analyses. Hydrau!ic analyses performed by FPC on the DH System in the LPI mode shows that throttling LPI flow to approximately 1300 gpm, as indicated on the main control board by either DH-1-FIl or DH bFI2, will provide flow in the APS line which exceeds the values necessary to provide boron dilution by that path.

EOP instruction and procedures in the Technical Support Center (TSC) will contain the means for operators to ensure adequate flow through the APS line. Regarding DTS, when the DH drop line is verified to be open, using valve position indicators with the appropriate plant procedure, analyses show that the elevation head provides the driving head necessary to ensure adequate flow through the drop.me to the RB Emergency Sump and to provide boron dilution.

The measurement of boron concentration using the Post Accident Sampling System (PASS) is the best measure of the effectivoess of boron dilution. Sump sampling is effective for determining adequate core boron concentration control for both APS and DTS. As discussed lJow, the amount of time required to obtain feedback regarding the effectiveness of the boron dilution method will be a function of the boron dilution method used.

In the event of a LBLOCA, where DTS will be used, the increase in RB Emergency Sump voron concentration will be almost immediate, once the core volume begins flowing through the hot leg to the RB Emergency Sump. DTS allows the hot leg liquid to flow directly into the RB Emergency Sump, which is within several feet of the location of the PASS boronometer sample point. If a LBLOCA in the cold leg were to occur, approximately 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> would be available

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c U.hi. Nuclear Regulatory Comtaission 3F1297-21 Page 3 of 4 e

prior 'o possibly reaching an unacceptable boron concentration in the core. This is sufficient time to:

1.

deterraine that an active method of boron concentration control is required.

2.

initiate DTS, and 3.

obtain sump concentration information for the control room and TSC to demonstrate adequate core boron dilution is taking place.

In the event of a SBLOCA in the cold leg, where APS may be required, the time available to conclude the APS method is effectively diluting core bcron will be longer than for the DTS method. This is becat'se the higher RCS temperatures support higher boron concentrations, thus increasing the time before initiation of APS is required. When APS is initiated, the flow path is from the hot leg throu;;h the core with mixing of the highly borated core liqaid in the RV downcomer and ultimately out the break and to the sump. ECCS flow will t'e drawn from the RB Emergency Sump to provide sufficient mixing of the break flow with the recirculating volume of water on the RB floor so that an increase of the sump boren concentration will be measured. The PASS borenometer wiil be used to provide feedback to the control room and Technical Support Center to ensure adequate core boron dilution is taking place.

LAR #220 was submitted to revise the wording in License Condition 2.C.(5) because the condition, as written, is no longer necessary to assure that CR-3 post-LOCA boron dilution methods are effective. FPC restates its request that the NRC review LAR #220 and issue an amendment to the CR-3 operating license as requested by FPC.

The additional information provided in this letter supports the previous conclusions of the "No Significant Hazards Consideration" in accordance with 10 CFR 50.92(c) that were inciuded with LAR #220. Moreover, because the information submitted is responding to NRC questions and comments arising during the review of LAR #220, and the scope of the amendment requested remains unchanged, FPC does not consider that any additional public notice in accordance with 10 CFR 50.91(a)(2) is necessary.

FPC has reviewed the information discussed in Information Notice 97-43, " License Condition Compliance." It does not present any new information that has not already been considered by FPC.

Operating License Condition 2.C.(5) was created in late 197f to assure that flow indicators were installed within a specified time limit (six months) of issuance of the Operating License. This Condition 2.C.(5) was fulillied and the flow indicators became part of the CR-3 plant design. As discussed above, FPC has the capability to ensure that adequate flow for post-LOCA boron dilution exists through measurement methods and verified analyses. Considering the low decay heat in the CR-3 core, the safety significance of not having the specific flow indicators DH-45-FI and DH-46-FI operable in Modes 4 or 3 is negligible. Also, operation in Modes 4 or 3 without these flow indicators but with the capability proposed by LAR #220 will ensure that CR-3 will fulfill its intended safety functions. However, FPC has conservatively

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• U.'S. Nuclear Regulatory Commission 3F1297-21 Page 4 of 4 assumed that deletion of the Operating License Condition would be a restraint to entering Mode 2. Therefore, FPC requests consideration and approval of LAR #220 as soon as possible to support CR-3's restart in December,1997.

The attachment to this letter contains responses to specific questions raised by the NRC during a visit to CR-3 on November 3 through 7,1997. There are na commitments in this letter. If you have any questions regarding this submittal, please contact Mr. David Kunsemiller, Manager, Nuclear Licensing at (352) 563-4566.

Sincerely, f

N/Lc

l. J. Holden Director Site Nuclear Operations JJH/krc/pvf/jwt Attachment xc:

Regional Administrator, Region II Senior Resident Inspector NRR Project Manager

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U.S. Nuclear Regulatory Commission Attachment 3F1297-21 Page 1 of 4 ATTACHMENT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST #220 Change to License Condition 2.C.(5)

During the November 3 through 7,1997, meetings between the NRC and FPC at CR-3, the NRC discussed the presentation of information in the appropriate sections of Attaciunent A of Reference 1 that contains sections that describe the Summary of Changes and Justification for Request. The NRC requested that additional information be provided.

1.

The NRC requested that FPC provide information to clarify the effectiveness of the Reactor Vessel Vent Valves (RVVV) and hot leg injection via the Auxiliary Pressurizer Spray (APS) hne as mitigation methods given that the B&W Owners Group (B&WOG) concluded, in 1991, that these flow paths were not as effective as originally thought in the B&W 'Iopical Report BAW-10103.

FPC provided results of new analysis in LAR #223 (Reference 2) which demonstrated the ranges of break sizes over which the active and passive methods for boron precipitation mitigation are effective. These analyses are being further refined and will be submitted to the NRC in response ta a request for additional information received during meetings held November 3 through 7,1997.

2.

FPC made the statement, " Flow through these lines will be demonstrated by the position indicators of the valves in the associated flow paths." The NRC requested that FPC clarify how position indication will be used.

Fundamentally, the only time flow indicators DH-45-FI and DH-46-FI would have been used is to confirm that the active method, when initiated, is working. Prior to initiating an active method, operators have Reactor Coolant System (RCS) temperature, pressure, sukooling margin, and Reactor Building (RB) Emergency Sump (WDSU-1) concentration as a means to track system conditions. As long as adequate subcooling margin exists, there will be no need to initiate an active method because the boron concentrating mechanism does not exist. CR-3 operators will have the following indication in lieu of flow at the time an active methoc' is initi ted to ensure the active methods are functioning:

(a) valve position indication for valves in the Decay Heat (DH) drop line dump-to-sump (DTS) and the APS flow paths will assure that any flow path is open.

As discussed in Reference 3, the valves associated with the DH drop line DTS and the APS line have safety-related position indicators.

m U.S. Nuclear Regulatory Commission Attachment l

3F1297-21 Page 2 of 4 l

(b) for APS flow - procedures will direct flow to be established by throttling Low Pressure Injection (LPI) pump flow to maximize APS flow for a given RCS pressure and then fully opening valves DHV-91 ar.d RCV-53 in the APS line.

Boron sampling in the RB Emergency Sump will be the indication that t'ais method is diluting boron concentration within the reactor vessel.

(c) for DH drop line (DTS) - procedures will direct flow to be established by fully opening valves DHV-4, -41, either DHV-39 or DHV-40, then partially opening either DHV-42 or DHV-43.

DHV-3 will then be fully opened aligning the drop line that connects to the RB Emergency Sump. Boron sampling in the RB Emergency Sump will be the indication that tb;s method is diluting boron concentration within the reactor vessel.

/v. stated in LAR #220, the original purpose of flow indicators DH-45 FI and DH-46-FI located in the DH System drop line and the APS line, respectively, was to enable the operator to verify that the flow rate is at least 40 gpm. The intent of the statement questioned by the NRC was to indicate that FPC will use the safety-related valve position indicators coupled with analyses and use of RB Emergency Sump boron concentration to monitor the effectiveness of the method rather than using the flow indicators.

3.

There is a discussion in LAR #220 of use of the Post Accident Sampling System (PASS) for determining the degree to which any boron precipitation prevention methodology is successful.

The NRC noted that other boron precipitation prevention methods are described in LAR #223 and the differentiation between LAR #220 and #-223 needs to be clarified.

LAR #220 requests NRC approval to revise License Condition 2.C.(5) of the CR-3 Operating License. LAR #223 requests NRC approval of a revised licensing basis for post-LOCA boron precipitation prevention. Although both License Amendment Requests are free standing, FPC referenced LAR #223 in its LAR #220 to ensure that the NRC was fully aware of both licensing actions.

As explained in the response to request #2 above, the RB Emergency Sump boron concentration is a key indicator of both the need to initiate an active methed for dilution and for monitoring the effectiveness of the act;ve method. When the NRC imposed Operating License Condition 2.C.(5) in 1976, the primary means to determine boron control effectiveness was by flow indication. Therefore, FPC installed flow indicators DH-45-FI and DH-46-FI located in the DH drop line and the APS line, respectively. FPC is modifying its methods for post-LOCA boron precipitation controls and will use valve position indication, RB Emergency Sump boron concentration, and sunporting analysis to confirm that the active methods are effective. The discussion in question should have stated that License Condition 2.C.(5) and therefore, the flow indicators, are no longer necessary to support the CR-3 boron precipitation prevention methodologies.

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- ' - U.S. Nuclear Regulatory Commission Attachment

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3F1297-21 Page 3 of 4 4.

The NRC questioned whether the CR-3 operators ever used flow indicators DH-45-FI or DH-46-FL Previous sersions of the Emergency Operating Procedure (EOP) for "LOCA Cooldown" (EOP-8) and the Operating Procedure for the Decay Heat Removal (DH) System (OP-404) referred to the subject flow indicators. After the B&WOG _ determined that the APS method was ineffective as a boron precipitation prevention method, EOP-8 was revised to remove DH-46-FL In October 1996, FPC determined that DH-45-FI and DH-46 ei were not operable because of hardware problems. At that time, FPC initiated corrective action plans that included submitting a license amendment to revise Operating License Condition 2.C.(5) and removing the indicators from procedures. FPC also began investigating alternative methods for bcron precipitation mitigation. Approval of LAR #220 is required for CR-3 to restart from the current outage since the flow indicators are no longer used in the CR-3 boron precipitation prevention plan and the hardware no longer operable.

5.

The NRC noted that in the Justipcationfor Request the table describing Post-LOCA boron precipitation methods contains a discussion of the APS method, and that it would take "several days" after the accident for the APS method to become effective. In 1991, the B&WOG stated that this was approximately 46 days based on a maximum flow of 40 gpm.

The NRC asked FPC to clarify what is meant by "several days?"

New analysis being submitted to respond to a request for information on LAR #223 shows that with adequate LPI flow, APS flow from DHP-1B will be in the range of 75.8 gpm -

to 114.5 gpm at RCS pressures of 60 and 0 psig, respectively. ' Flow from DHP-1A will be greater. The values for LPI flow used in this analysis bounds the maximum value -

allowed per the procedure with an allowance for instrument error. Based on these flow rates, ' PS will become effective in preventing boron precipitation approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> A

following the LOCA.

6.

In the Justification for Request section, FPC stated when the operators are procedurally instructed to open either DHV-42 or DHV-43 (RB Emergency Sump isolation valves -

located outside the RB) to p4 vide e flow path from the reactor vessel through the DH drop line to the RB Emergency Sump, that this action would allow " blowdown" to occur.

The NRC requesteil clarification of the extent of this blowdown.

This statement was not meant to imply an uncontrolled release of energy into the RB Emergency Sump, but that a flow path would be available from the RCS to the RB Emergency Sump. When this method is used, flow from the RCS to the RB Emergency Sump will commence and the RCS pressure will decrease accordingly, eventually equalizing with the RB.

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.,a U S. Nuclear Regulatory Commic.sion Attachment

- 3F1297 Page 4 of 4 7.

. The paragraph following the table in the Justificationfor Request section made a statement that approximately _10 gpm is required through the DH Systern drop line to provide adequate boron dilution flow. The NRC requested clarification of whether this flow is

. drop line flow or core flow?-

The analysis presented in Reference 2 refers to drop line flow and shows that any DH L System drop line dump-to-sump flow m excess of 10 gpm flow will provide adequate boron dilution flow through the core, 8.

The first sentence on page 4 of Attachment A states "Like the DH System drop line method, flow is asured by opening the valves =in the flow path..."

This could be interpreted to mean that both the DH System drop line and the APS could be in use since the term "several days" is used again. The NRC requested clarification of this statement.

FPC does not intend to use both methods simultaneously. At the time APS becomes available, following a larger break, it is an alternative to the DH drop line dump-to-sump method. APS is preferred for all but LBLOCAs because of the fact that the ECCS flow -

path does not have to be significantly altered. However, there is a time delay associated with this path since the pressurizer.must be filled before flow is established to the core.

FPC will be providing upor.ed analyses discussing the use of the DH drop line dump-to-sump and the APS methods and boron dilution effectiveness in a forthcoming supplement to LAR #223.

Summary:

FPC concludes that the necessary instrumentation and assessment tools to determinc boron precipitation control methods are implemented correctly, and they exist, are effective, and will be used as accessary during an accident. TSC guidance will contain directions on which dilution method should be used, and when it should be used. The Emergency Opera:ing Procedures will contain instructions for alignment and verification of boron dilution flow paths through either the Auxiliary Pressurizer Spray line or the DH System drop line.

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