ML20138G469

Summary of 970409 & 10 Meeting W/Util in Baxley,Ga to Discuss Analysis & Design Features of Unit 1 & Unit 2 SFPs & Associated Cooling Sys.List of Attendees Encl

ML20138G469
Person / Time
Site:	Hatch
Issue date:	05/05/1997
From:	Jabbour K NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
TAC-M98303, TAC-M98304, NUDOCS 9705060304
Download: ML20138G469 (10)

Text

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.i p k UNITED STATES -

j g j NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. 3000H001 May 5, 1997

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! LICENSEE: Southern Nuclear Operating Company, Inc.

i l FACILITY: Hatch Nuclear Plant, Units 1 and 2

SUBJECT:

SUMARY OF APRIL 9 AND 10,1997, MEETING ON THE SPENT FUEL POOL

! REGULATORY ANALYSIS FOR HATCH UNITS 1 AND 2 (TAC NOS. M98303 AND

! M98304)

Introduction i

On April 9 and 10, 1997, the NRC staff and its consultant from Idaho National

! Environmental and Engineering Laboratory (INEEL) met with Southern Nuclear l Operating Company, Inc. (SNC) representatives at Plant Hatch, Baxley, Georgia, I to discuss the analysis and design features of the Unit I and Unit 2 spent i fuel pools (SFP) and associated cooling systems at Hatch. Enclosure 1 lists  !

the attendees and Enclosure 2 provides the SNC responses to the information requested by the NRC in a meeting notice dated March 27, 1997.

Discussion As a result of the Spent Fuel Pool Action Plan, the staff committed to perform regulatory analyses at several operating nuclear power plants, including i Hatch, to determine whether plant-specific safety enhancement backfits could J be justified. The objective of this meeting was to review design and  ;

operational information regarding the two Hatch spent fuel pool systems that l will be used in an SFP probabilistic risk assessment (PRA). The PRA will focus on the following design issues as they relate to loss of SFP inventory  ;

and loss of SFP cooling events: (1) instrumentation to aiu operators during a i loss of SFP coolant (inventory) event; (2) instrumentation to aid operators during a loss of SFP cooling event; and (3) the impact on safety-related equipment due to sustained boiling of a spent fuel pool. The staff also reviewed the role of the Residual Heat Removal system (in the fuel pool cooling assist mode), and the Decay Heat Removal (DHR) system as a source of additional cooling for the fuel pool during periods of high heat load or when the normal fuel pool cooling system is unavailable.

Messrs. O. Vidal and G. Warren, SNC, began the meeting with a discussion of the design and operation of the DHR system. The system, a fully redundant, 100% capacity cooling system, was permanently installed in 1994 and can provide cooling to either unit's spent fuel pool. The meeting attendees toured the SFP area, walked down the DHR system, and discussed the potential moisture propagation paths throughout the secondary containment in the event a spent fuel pool were to boil. The plant walkdown also included a review of the fuel pool cooling system control panel and the controls and indications available to the operators in the control room. After the plant walkdown, the NRC staff reviewed design and procedural documents, and system drawings provided by the licensee's staff.

i NRC HLE CElHEh COPY /

e m &ro; ,70 sos PDR P

ADOCK 05000321 PDR (fd

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l Messrs. E. Ingram and J. Daily, SNC, discussed information in the existing l plant PRA that was relevant and could be helpful for conducting an SFP-PRA.

For example, numerical and modeling assumptions for the loss-of-offsite-power initiating event frequency were discussed.

Conclusion The staff will document the results of this analysis in a report that will be transmitted to the licensee.

kn)& O.

Kahtan N. Jabbour, Project Manager <

Project Directorate 11-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket Nos. 50-321 and 50-366

Enclosures:

As stated (2) cc w/encls: See next page

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May 5, 1997 Messrs. E. Ingram and J. Daily, SNC, discussed information in the existing plant PRA that was relevant and could be helpful for conducting an SFP-PRA.

For example, numerical and modeling assumptions for the loss-of-offsite-power

' initiating event frequency were discussed.

Conclusion The staff will document the result of this analysis in a report that will be tri Tsmitted to the licensee.

ORIGINAL SIGNED BY:

Kahtan N. Jabbour, Project Manager Project Directorate II-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket Nos. 50-321 and 50-366

Enclosures:

As stated (2) cc w/encls: See next page Distribution:

Hard Conv

' Docket File PUBLIC PD 11-2 Rdg.

0GC ACRS E-Mail SCollins/FMiraglia LBerry JJohnson, RII RZimmerman Dross (SAM) PSkinner, RII SVarga CGratton HBerkow Slee KJabbour BHolbrook GTracy, RII

• See previous concurrences To receive a copy of this document, indicate in the box: "C" attachment / enclosure "E" = Copy with attachment /enclosureJ%(k "M r No copyCopy without 0FFICE PM:PDII-2 LA:PDIIt 2? 1 SPLB:DSSA*u PRAB: DST *bs ji D:Pfgj /2,1 l NAME KJABBOUR:cn Wf LBERRY M GHUBBARD//// JFLACK 4 Y 18E@ bid '

DATE 4-/32 /97 N /\ /97 A/g/07 f'///#7 4/2$/97 M

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5 '/ / /97 / /97 DOCUMENT NAME: G:\ HATCH \MTGSUMM.410 0FFICIAL RECORD COPY bl

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Edwin I. Hatch Nuclear Plant j Units 1 and 2 l cC*

Mr. Ernest L. Blake, Jr. Mr. Thomas P. Mozingo Shaw, Pittman, Potts and Trowbridge Program Manager

! 2300 N Street, NW. Nuclear Operations i

Washington, DC 20037 Oglethorpe Power Corporatior.

J 2100 East Exchange Place Mr. D. M. Crowe P. O. Box 1349

Manager, Licensing Tucker, Georgia 30085-1349 Southern Nuclear Operating

Company, Inc. Charles A. Patrizia, Esquire

P. O. Box 1295 Paul, Hastings, Janofsky & Walker

Birmingham, Alabama 35201 12th Floor i 1050 Connecticut Avenue, NW.

Resident Inspector Washington, DC 20036 l U.S. Nuclear Regulatory Commission 4

11030 Hatch Parkway North Mr. Jack D. Woodard l

Baxley, Georgia 31513 Executive Vice President

! . Southern Nuclear Operating i

Regional Administrator, Region II Company, Inc.

U.S. Nuclear Regulatory Commission P. O. Box 1295 j 101 Marietta Street, NW. Suite 2900 Birmingham, Alabama 35201

! Atlanta, Georgia 30323 Chairman

! Mr. Charles H. Badger Appling County Commissioners Office of Planning and Budget County Courthouse

! Room 610 Baxley, Georgia 31513  !

! 270 Washington Street, SW. j

. Atlanta, Georgia 30334 Mr. H. L. Sumner, Jr. l 4 Vice President  :

j Harold Reheis, Director Southern Nuclear Operating l Department of Natural Resources Company, Inc.

205 Butler Street, SE., Suite 1252 P. O. Box 1295 Atlanta, Georgia 30334 Birmingham, Alabama 35201-1295 Mr. P. W. Wells Steven M. Jackson General Manager Senior Engineer - Power Supply Edwin I. Hatch Nuclear Plant Municipal Electric Authority Southern Nuclear Operating of Georgia Company, Inc. 1470 Riveredge Parkway, NW 11030 Hatch Parkway, North Atlanta, Georgia 30328-4684 Baxley, Georgia 31513 Mr. W. G. Hairston, III President and Chief Executive Officer Southern Nuclear Operating Company, Inc.

P. O. Box 1295 Birmingham, Alabama 35201-1295

! APRIL 9 AM 10. 1997 j NRC/SNC MEETING 1

LIST OF ATTEWEES l

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EC SE l K. Jabbour 0. Vidal i

j C. Gratton G. Warren I

1 S. Lee T. Metzler E. Ingram B. Holbrook ,

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! INEEL J. Daily l

S. Khericha P. Wells *

! S. Tipps 1

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• Attended exit meeting only Enclosure 1

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! j j NRC Ouection #1 1

I a) Can the gate be; ween the Unit I and Unit 2 SFPs be operated (opened or closed) at any

", time? b) What is the normal position (condition) of the gate (removed or installed)? c) If

the normal position is open (removed), how often is it installed and for how long? d) l 3 What administrative procedure (s) control whether the canal gate is installed or removed?

e) What operator actions are required? What assistance is available to the operators to  ;

manipulate the gate? l l

Hatch reennnse- i f 1 a) The transfer canal gates can bephysically removed or installed at any time, as long as

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power is available to the overhead crane. (This addresses only the physical capabilities to operate the gates, there are administrative controls which must be met. These are

, described below).

b) The normal position of the transfer canal gates is installed.

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! c) N/A, as stated above, the normal position of the gates is installed. They are removed

whenever fuel is transferred between the two pools or whenever the Unit I and 2 FPC q systems are crosstied.

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d) Procedure 52GM-T24- 001-Os provides procedural guidance on the installation and removal of the transfer canal gates. The gates are required to be installed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the completion of any fuel transfers between pools, or of any other activity which I required the removal of the gates. While the gates are removed, a person is assigned to I

] monitor water level in the pools on the refueling floor. Also, permission from the OPS. l l Mgr. must be obtained prior to removal of the transfer canal gates. All these controls 1

(along with a few others) are listed in the procedure for removal of the gates 52GM-T24-001-Os. i e) Removal and installation of the transfer canal gates is done by the maintenance dept.

under a maintenance procedure,52GM-T24-001-0s. ' Operator actions' consist of verifying that the transition assembly seals are adequately pressurized with air, and i' confirmation that no low pressure alarms are illuminated in the control room.

Maintenance personnel will then attach slings to the gates and raise them until clear of the canal, then store the gates in their designated storage locations in their respective (Unit 1 or Unit 2) spent fuel pools. All the details for removal and installation of the gates are provided in the above listed Maintenance procedure. i NRC Ouestion #2 What type ofinformation (or mode ofinformation display) is available to the operators to recognize a loss of SFP cooling event?

i Enclosure 2

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Hatch reennnae: ,

a) Hi temperature alarm on the fuel pool cooling heat exchanger inlet and outlet for Unit I and Unit 2. ,

These are annunciated in the main control room on the respective P654 panels for each unit. The associated annunciator response procedures are 34AR-654 -004-Is and 2s.

b) Low and High discharge pressure alarms for the fuel pool cooling pumps. .

These are alarmed in the MCR on the P654 panels of each unit. 34AR-654- 005-Is and ,

2s for the high discharge pressure alarms and 34AR-654-037-1s,2s for the low pressure alarms.  !

NRC Ouestion #3 l What is the success criteria for restoring SFP cooling?

Hatch Reennnme i The success criteria is clearing the high temperature annunciators, i.e., restonng temperature to less than 125*F for Unit 1. A second level success criteria is the . J prevention of boiling. l NRC Ouestion #4 What back-up system is available for SFP cooling? Given a loss of the normal cooling system, how soon can this system be available to provide the SFP cooling function?

What operator actions are required to cool the SFP via the back-up system What assistance is available to the operators?

Hatch recnonne There are several back-ups to the SFP cooling systems depending on the condition of the plant. During refueling outages, the decay heat removal system is normally aligned to the SFP of the unit being refueled. At certain periods during the outage it may be the primary system for decay heat removal. This it is immediately available during these periods. RHR fuel pool cooling assist is also available during outages, provided the 'B' Shutdown cooling loop is in service, and the fuel pool gates are removed with the cavity flooded. Placing Fuel Pool Cooling assist in service requires placement of a spectacle ,

flange in the fuel pool cooling to RHR piping. This will take several hours to perform (4 j to 6). The availability of the G71 system, however, has greatly reduced the need for RHR j assisted fuel pool cooling.

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During normal periods (Both units operating), the G71 system b normally not aligned to either pool. The Unit 1 FPC system may be crossconnected to the Unit 2 FPC system and used as a back-up. The Unit 2 FPC system however cannot be crossconnected and used

! to cool the Unit 1 pool. However, the transfer canal gates can be removed to promote circulation between the pools, in the event Unit 1 FPC is lost. Crossconnecting the FPC  ;

systems is discussed in Hatch procedure 34SO-G41-002-2s.

! It is also possible to assemble the G71 system and place it in service during normal 1 l operations as a back-up to FPC, however, this would take about 10 to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

Also, if no other means of cooling is available, feed and bleed may be used. That is, j feeding to the spent fuel pool with condensate water, hose stations or plant service water, 1 l and bleeding back to the condensate storage tank or radwaste. I NRC Ouestion #5 ,

Are there attemate cooling capabilities for the SFP? If yes, what are they and what i operator actions are required? What assistance is available for the operators? )

i Hatch response: i 1

See answer to question #4.

NRC Ouestion #6 - 4 a) What is the site-specific loss of offsite power (LOOP) initiating event frequency? b)

What LOOP recovery probabilities are assumed in the plant PRA? c) How many EDGs are available to be used for SFP cooling,if any? d) How long would it take to establish power to SFP cooling from the EDGs? e) Are any SFP recovery actions covered by the plant Emergency Operating Procedures?

Hatch Responce a) See attached information b) See attached information.

c) The SFP cooling pumps are not connected to essential power, thus the emergency diesel generators cannot supply power to the SFP pumps. However, a back-up D/G to the G71 system is available during high decay heat loads.

d) N/A, since the diesels do not supply power to the SFP pumps. However, if the emergency diesel generator is on-site and connected to the G71 system, power is available to the G71 (DHR) system immediately. Also, since the normal power to the G71 system is independent of the offsite power sources that supply power to the SFP ,

i system, it is possible that an LOSP which would result in the loss of SFP, would not result in a loss of power to the G71 system.

l e) There are no SFP recovery actions in the EOPs, that is the EPG based EOP. However, l recovery actions are listed in abnormal procedures. 34AB-G41-002-Is and 2s for loss of  ;

level. 34AB-G41-001-Is and 2s is for loss of cooling.

l NRC Onection #7 j Upon loss of SFP, and assuming cooling is not restored, how long would it take for the  :

SFP to begin boiling? Assume the SFP decay heat load is based on a full SFP (one third I core recently discharged from a 30 day outage), ultimate heat sink at its design condition, ;

and the loss of SFP cooling occurs one week after restart.

Hatch reennnse-1 See attached response.  ;

NRC Ouestion #9 l What initiating event frequency is assumed for loss ofinventory event (e.g., due to seal failure, piping failure, sipL,ning event) for the SFP? What isolation mechanism (Active or passive) are available?

Hatch Resnonse Hatch does not currently have a shutdown PRA model. Therefore, the loss of SFP inventory event is not modeled. There is a Double check valve assembly on the diffuser ,

discharge designed for siphon protection. I NRC Ouestion #10 What indications / indicators are available to the operators to recognize a loss of SFP inventory event? Where are they located? Where do they provide indication / alarm? Are they safety related? j Hatch retnnnee*

There are spent fuel pool low level annunciators in the control room located on the P654 panel. The associated annunciator alarm procedure is 34AR-654-022-Is,2s. The instrumentation for this alarm is not safety related.

Additionally, the skimmer surge tanks have low level alarms associated with them that also alarm in the main control room and locally in the fuel pool pump and heat exchanger

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rooms. The annunciator response procedure associated with these alarms are 34AR-654-067 and 068-Is and 2s. The instrumentation for these alarms is not safety related.

Additionally, there are leakage detection system alarms in the MCR for the FPC system ,

gate seals (34AR-654-006-1s,2s) refueling bellows (34AR-654-031-1s,2s), transfer canal seals (34AR-654-038-2s), and also low air supply pressure alarms for the transfer canal seals (34AR-654-051 and 066-1s).

NRC Ouestion #11  ;

List the make-up sources to the SFP in order of priority (for use). What operator actions are required to operate the systems? What operator assistance is available, if any?

Hatch recnonne*

Per 34AB-G41-002-Is and 2s, Decreasing RX Well/ Fuel Pool Water Level:

1) Make-up from Condensate Storage Tank.

This requires operating valve G41-F041. This valve has a remote operator on panel IH21-P155 on the 207 elevation of the Unit I reactor building. For Unit 2, the analogous valve is 2G41-F054. It is located on the 185' elevation of the Unit 2 reactor building.

2) Demineralized water and fire water hose stations This will require obtaining hoses and fittings for the water hose stations on the refueling floor.

3) Plant Service Water.

This will require three local manual valve manipulations.

Note: Hose stations and PSW are listed on the same step in the procedure. However, it  ;

would be advisable to use the hose stations before PSW since this is much cleaner water l (demin water). If the leak were very large, however, it may be necessary to more quickly use PSW due to the larger flow rate.  !

Other questions- 1 1

The average outage length is about 35 days. We havejust begun to perform partial core offloads and will continue to do so in the foreseeable future. Notwithstanding some unforeseen event which may call for the entire core to be off-loaded. )

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