3F0298-11, Forwards Description of Conclusions Reached by Util After Research of Original Licensing & Design Basis for LPI Crossover Line & List of Commitments Re Issue

Forwards Description of Conclusions Reached by Util After Research of Original Licensing & Design Basis for LPI Crossover Line & List of Commitments Re Issue

ML20202A935
Person / Time
Site:	Crystal River
Issue date:	02/06/1998
From:	Rencheck M FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F0298-11, 3F298-11, NUDOCS 9802110027
Download: ML20202A935 (8)

Text

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9.

Florida Power CORPORA %N k 30 3 Februsry 6,1998 3F0298-11 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Subject:

Low Pressure injection Crossover During Long-Term Cooling

Reference:

FPC Letter to NRC (3F1297-37) dated December 29,1997 l

Dear Sir:

l Florida Power Corporation (FPC) was requested to provide a discussion regarding the use of the low pressnre injection (LPI) crossover line during a loss of coolant accident (LOCA).

Several questions related to this subject were raised during recent NRC Emergency Operating g Procedures (EOP) Inspections (50-302/97-12 and 50-302/98-02). Attachment B to this letter

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provides a description of conclusions reached by FPC aner research of the original licensing ,

and design basis for the LPI crossover line and also ad resses related valve positions pertinent to this issue. FPC has determined that correcticas are required in the Final Safety Analysis Report (FSAR) to properly reflect the use of the LPI crossover capability.

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FPC will analyze system configuration and consider possible engineering solutions to enhance system performance. This analysis will includc further review of the normal standby positions of the LPI injection valves (DHV-5 ar.d DHV-6) and the LPI suction valves from the borated water storage tank (DHV-34 and DHV-35). la addition, the analysis will evaluate the continued use of DHV-5 and DHV-6 for throttling flows during the LPI/HPI piggyback injection mode of operation.

FPC previously committed in the referenced letter to submit documentation to resolve an unreviewed safety question related to DHV-34 and DHV-35 by February 27, 1998. The due date for this commitment is being extended to October 16, 1998, to allow time for the 9002110027 980206 '

{DR ADOCK 05000302 PDR lfll,hl.lliel ' l h-

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CRYSTA!. RIVER ENERGY COMP?.EX: 15760 W. Power une Street . Crystal Rwer, Florida 34428-6708 (352) 795 6486 A Florida Progress Cornpany

. U.S. Nuclear Pegul: tory Commission 3F0298-11 Page 2 co'o rdinated' completion of the required analyses for the LPI valves and preparation of the license amendment request.

Attachmert A provides the list of commitaxats made in this submittal. Please contact Mr.

- David Kunxmiller, Manager, Nuclear Licensing at (352) 563-4566 if you have any questions

- regarding this information.

Sincerely, M.W. Renchxk, Director Nuclear Engineering and Projects MWR/twc/gew I Attachments

- cc: Regional Administrator, Region II Senior Resident Inspector NRR Project Manager.

Walt Rogers, Region II

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- U.S. Nuclear Regulatory Commission Attachment A 3F029811 Page 1of1 ATTACIBIENT A 1.IET OF COMMITMENTS The following table identifies.those actions committed to by Florida Power Corporation in this document. Any other actions discussed in the submittal represent intended or planned actions by Florida Power Corporation. They are described to the NRC for the NRC's information and are not

_ regulatory commit:nents. Please notify the Manager, Nuclear Licensing of any questions regarding this document or any associated regulatory commitments.

. ID Number Commitment Due Date 3F0298-11-1 FPC will evaluate the failure to implement the original commitment to the October 16,1998 NRC regarding valves DilV-5 and DHV-6 in accardance with the CR-3 corrective action program. FPC will also evaluate the use of these valves for throttling flow. As part of this evaluathn, FPC will consider possible engmming solutions to enhance system performance.

3F0298-It 2 FPC previously committed by letter dated December 29,1997 (?F1297-37), October 16,1998 in response to Notice of Violation No. 50-302/97-1413, to issue a License Amendment Request to the NRC resolving the unreviewed safety qu< Mn-involving valves DHV-34 and DHV-35. Tais commitment is reviset i incorporate a new dae date, j

e U.S. Nuclear Regulatory Commission Attachment B 3F0298-11 Page 1 of 5 n

ATTACHMFNr B .

USE OF LP! CROSSOVER INJECTION MODE OF OPERATION FOR LONG-TERM COOLING issue Section 6.1.2.1.2 of the Crystal River Unit 3 (CR-3) Nuclear Plant Final Safety Analysis Report (FSAR), Revision 23, describes t!'e low pressure injection (L.PI) design. In this description, the use oi the LPI crossover line is described as follows:

LPIis accomplished through two separateflowpaths, each including one pump and one heat exchanger and terminating directly in the reactor vessel through corefooding no:zles located on opposite sides of the vessel. The LPI System is e provided with a crossover line to permit one LPI stringpow of 3,000 gpm to be split equally, thus providing a minimum of1,500 gpmflow to both corefooding injection nozzles simultaneously should a coreflooding line or one LPIpump ,

fail.... The LPI crossover injection mode of operation is accomplished by opening the crossover line, prodded with a neonmyflow element between the separate and indepenkst LPI strings, and remotely adjusting theflow through a the crossover line to 1,500 gpm via two (one in each LPI string) electric motor .

operated valves (see Figure 9-6). '

Section 6.1.3.2 of the FSAR also states:

Low pressure injectionflow in the recirculation mode is restricted to 2200 gpm (indicated) per pump to meet LPIpump and BS pump NPSH requirements with the available Reactor Building Emergency Sump levels aper BWSTsupover. The 2200 gpm indicated mlue isfor the LPI only. The actual DHpumpflow is higher -

(3056 gpm) when 100 gpm recirculationflow and 570 gpm ofpiggy-back HPIis considered...

To establish the LPI Crosstie configuration, crossover valves DHV-7 and DHV-8 would be opened and injection. valves DHV-5 and DHV-6 would be throttled to provide flow to the core. The attached Figure 1 is provided to aid in understanding and review of the LPI design.

The Emergency Operating Procedures (EOPs) did not, at the time the NRC EOP Inspection 97-12 commenced, direct the use of this design feature although it is discussed in the Babcock and Wilcox Owners Group (3&WOG) Generic Emergency Operating Guidelines Technical Basir Document (TBD). To address this issue, FPC generated a deviation document addressing the absence from the EOPs of the TBD directed use of the LPI crossover line during the initial phase of mitigating loss of coolant accidents (LOCA). The deviation document was developed in accordance with NUREG 1358, "Lenons Learned from the m 1

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• U.S.' Nuclear Regulatory Commission' ' Attachment B-

_ ' 3F0298-11L -

Page'2 of 5 .

St iecial Inspection Program for Emergency Operating Procedures." FPC subsequently

, developed procedural' guidance for use of the LPI crossover configuration for long-term core icooling. '

An operating procedure previously contained guidance for establishing LPI crossover; .

! however, this guidance was removed in 1996. - The basis for not impkmenting the LPI - i crossover alignment was due to instrument uncertainties and 'possible net positive suction head (NPSH) concerns while providing suction to the high pressure injection (HPI) pump during--

transition to LPI crossover. The LPI crossover feature does not require HPI/LPI piggyback to

^casure its use; however, HPI/LPI piggyback is relied upon during the initial phase of the

. LOCA and the NPSH concern supported the decision to discontmue the crossover guidance.  ;

1 Recent analysis was performed by Framatome Technologies,'Inc. (FTI) to support the development of a new procedure, Emergency Plan Implementing Procedure EM-225E,

- Guidelines for Long Term Cooling." The new procedure provides' acceptable crossover flow

- rates to remove core decay heat based upon time after the initiating event.; This procedure also -

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provides instructions for use of the LPI crossover configuration during the initial phase of a LOCA if a HPI pump is not available (e.g., following multiple equipment failures).

F=q ry Core CaaHn= Syhn ECCS) Origbal ik "-- Ramle

The description of the LPI crossover line was originally added to the CR-3 FSAR in

Amendment 32 dated October 1,1973, and has not been modified since that time except for minor editorial changes. At the time this description was provided,~ ECCS qualification.- -

requirements were included in the Commission's Interim A ceptance Criteria and the ECCS-3 analysis for CR-3 was not complete.

- The original and current licensing and design basis of the ECCS is based.on Topical Report

' BAW-10103A; "ECCS -Analysis of B&W's 177-FA Lowere<!-Loop NSS," Revision 3, dated 2

July.1977. Section 3.2 of Appendix .C to BAW-10103A describes the 0.44-ft Core Flood

- Tank (CFT) Line Break transient analysis. In this analysis, only one CFT and one HPI pump are credited to mitigate the consequences of the accident. The analysis demonstrates that all five Acceptance Criteria in 10 CFR 50.46 are met. The analysis performed for the CFT Line Break (BAW-10103A) to satisfy the requirements of 10 CFR 50.46 does not credit LPI flow or LPI crossover flow.

Section 10 of BAW-10103A describes operator actions for performance of maintenance that may be necessary fcr long-term cooling and provides several alternatives for opetion of-

- emergency _ core cooling systems that "can" be used during long-term cooling. One of these alternatives includes the use of the crossover 11e valves and split flow between two LPI lines.

The other alternatives include the use of two normal paths of LPI and the use of the LPI!HPI piggyback injection mode of operation. FPC has determined the latter two alternatives are sufficiently diverse to ensure adequate core cooling given any postulated single failure. The LPI crossover injection mode of operation may be used for performing maintenance during long-term cooling, or in the initial phase of the accident in the event of multiple fanures.

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. 1 t U.S. Nuclear Regulatory Commission ' Attachment B-3F0298-11 Page 3 of 5 FPC has included the use of this mode of cooling in the strategies for ensuring maintenance of 2 long term core cooling. Procedural guidance has been developed which describes the use of

. the LPI crossover injection mode of operation and the plant conditions and equipment i availability which would be considered in the decis!an to use this alternative alignment. These instructions are included in an EOP support procedure, and address each of the primary methods necessary;to assure long-term cooling. This procedure has been validated and will be

- controlled similar to EOPs. The procedare has been made_ availab!c in the control room and the technical support center (TSC), and trainmg was provided prior to entering Mode 2 from

-- the current outage. These actions, along with existing procedures, ensure that all three=

. methods described in BAW-10103A for performing maintenance activities during long term cocling are implemented at CR-3.

-Based on the licensing and design basis reviews performed to address use of the LPI crossover

~ line, the need to revise the FSAR was identified. This revision clarifies tM desaiption of the LPI crossover line to accurately reflect the design and licensing basis and the use of the LPI i

crossover line injection mode of operation for assuring long-term cooling for any LOCA event. This clumge also prioritizes the other, more preferred methods, for performing L maintenance activities during long-term cooling following a LJCA.

Nar===3 %=Ajv Paal*lan of LPI Inle*Ian Valves 1

A subset of the concern regarding LPI crossover capability is the normal standby position of the LPI injection valves, DHV-5 and DHV-6.

Motor-operated valves DHV-5 and DHV-6 are normally closed and energized, and fully open Jupon receipt of an engineered safeguards actuation system (ESAS) initiation including high

- Reactor Building (RB) pressure > 4 psig, or low-low Reactor Cqalant System (RCS) pressure

<500 psig.1 A review was performed of docketed correspondence regarding the normal positions of valves DHV-5 and DHV-6. Subsequent to 1976, the correspondence consistently l

~ indicated these valves were normally closed and energized. - A failure of one of these valves to open will not adversely affect meeting the requirements of 10 CFR 50.46 since the analysis has considered failure of a complete train of ECCS. The LPI/HPI piggyback injection mode Of operation will be used to maintain long-term cooling. Therefore, the initial position and possible failure of one of these valves does not prevent the establishment and maintenance of L long-tenn cooling in the piggyback mode.

lAs neted during the recent NRC EOP inspection, FPC made.a commitment to the NRC on January 13,1976 (letter 3F0176-03) to place the LPI injection valves in the normally open and energized standby position. This commitment was not completed and may have been changed without clear documentation of any discussions with the NRC, .Although the commitment included a statement that the FSAR would be revised prior to receipt of the Operating License,

the FSAR was neyed modified.

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• - U.S. Nuclear Regulatory Commission - Attachment B l 3F0298-11 Page 4 of 5 i

Also, during the NRC EOP Inspection, the inspectors questioned the need to throttle DHV-5 l'

and DilV-6 during the transfer of LPI pump suction from the borated water storage tank (BWST) instead of relying on motor-operated LPI pump discharge valves, DilV-110 and DilV-111. These valves (DHV-110 and DHV-111) are maintained throttled open with their associated flow controllers set for automatic operation at 3000 gpm during modes of operation which require LPI to be operable as defined in the CR-3 Technical Specifications. These j

valves are initially used to automatically throttle LPI flow through each separate LPI train.

} The 3000 gpm flow rate was described in FPC's letter dated December 16,1976 as the normal flow rate of the system within tN range of the 2800 gpm low flow setpoint and the 3100 gpm high flow setpoint. The December 1976 letter states the "high flow setpoint maintains the LPI pump within the calculated available NPSil for the entire system operating spectrum (initial injection and recirculation modes)."

FPC will evaluate the failure to implement the original commitment to the NRC regarding valves DHV-5 and DHV-6 as well as their use as throttle valves, in accordance with the CR-3 corrective actien program, As part of this evaluation, FPC will consider possibl; engineering solutions to enhance system performance. These evaluations will be complete by October 16, 1998.

Normn1 Standby Pasition of LPI Suction Valves from the BW" Although not a subset of the concern regarding LPI crossover, the motor-operated LPI suction valves from the BWST are valves in the direct flow path for initial LPI operation prior to recirculation from the RB sump. FPC did not maintain a commitment made in a letter to the NRC on January 13,1976 (letter 3F0176-03) to place the LPI suction valves from the BWST (DHV-34 and DHV-35) in the normally open and energized standby position. DHV-34 and DHV-35 were placed in the closed standby position as a result of 10 CFR 50, Appendix R reviews conducted in 1985 which did not recognize the original commitment made to the NRC.

In the normal standby valve lineup, DHV-34 and DHV-35 are closed and energized, and fully open upon receipt of an ESAS initiation including high RB pressure > 4 psig, or low-low RCS pressure < 500 psig. These valves were origi) ally maintained normally opened and energized at the time CR-3 received its Operating License, but were since reconfigured as normally closed and energized to resolve Appendix R concerns where postulated fires could, through spurious operation of specific motor-operated valves, result in draining the BWST to the RB sump. The reconfiguring of these valves was reviewed during the recent Safety System Function Inspection (SSFI) conducted by the NRC, and corrective actions to resolve

- NRC concerns telated to these valves identified in SSFI Inspection Report No. 50-302/97-14 are in progress. FFC has determined that changing the normal standby position of these valves from normally open to normally closed represented an unreviewed safety question.

However, FPC has also determined that the change is safe and operability of the valves and ECCF is met with the valves normally closed and energized. A failure of one of these valves to open will not adversely affect meeting the requirements of 10 CFR 50.46 since the analysis l

U.S. Nuclear Regulatory Commission ' Attachment B 3F0298-11 - Page 5 of 5 his considered failure of a complete train of ECCS. Therefore, the initial position and possible failure of one of these valves does not prevent the establishment and maintenance of long-term cooling. '

FPC previously committed by letter dated December 29,1997-(3F1297-37), in respc.ise to -

Notice of Violation No. 50-302/97-14-13, to issue a License Amendment Request to the NRC _ . c resolving the unreviewed safety question involving valves DHV-34 and DHV-35. This commitment is being revised to incorporate a new due date of Octcber 16,1998 The reason - -

- for this change in commitment date is to allow time _ for properly evaluating the normal standby _

_ positions of these valves as well as the other LPI valves important in implementing the LPI-crossover injection mode of operatioa during long-term core cooling. This will allow sufficient time to consider all i the issues raised during the NRC EOP inspection, and coincides with the completion date for all long-term corrective actions identified in this letter.

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