ML20151Y331

Forwards Shutdown Events & Scenarios Used in Review of NUMARC Guidance,Per Request.All Questions Should Be Directed to Listed Individual

ML20151Y331
Person / Time
Issue date:	09/11/1998
From:	Chris Miller NRC (Affiliation Not Assigned)
To:	Alexis Nelson NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT &
References
PROJECT-689 NUDOCS 9809180199
Download: ML20151Y331 (17)

Text

September 11, 1998 Alin N:Ison Nucirr En:rgy Institut) 1776 Eye Street, NW, Suite 400 Washington, DC 20006-3708

Dear Mr. Nelson:

In a letter dated August 3,1998, we provided you comments on Nuclear Energy institute's (NEl's) guidance for development of emergency action levels applicable in the shutdown and refueling modes of plant operation. After receipt of these comments, you requested a copy of the shutdown events and scenarios which were used in our review of NEl's guidance. In response to your request, please find attached the shutdown events and scenarios used in our review. If you have any questions regarding this matter, please contact Jim O'Brien of my staff at 301-415-2919.

Sincerely, Origirial signed by:

Ric.hard L.

Eatch For.

Charles L. Miller, Chief Emergency Preparedness and Radiation Protection Branch Division of Reactor Program Management Office of Nuclear Reactor Regulation 9809190199 980911 PDR REVGP ERGNUMRC PDR Project No. 689

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September 11, 1998

. Alin Nels:n Nucl:rr En:rgy Institut3 1776 Eye Street, NW, Suite 400 Washington, DC 20006-3708

Dear Mr. Nelson:

In a letter dated August 3,1998, we provided you comments on Nuclear Energy Institute's (NEl's) guidance for development of emergency action levels applicable in the shutdown and refueling modes of plant operation. After receipt of these comments, you requested a copy of the shutdown events and scenarios which were used in our review of NEI's guidance. In response to your request, please find attached the shutdown events and scenarios uced in our review. If you have any questions regarding this matter, please contact Jim O'Brien of my staff at 301-415-2919.

Sincerely, original signed by:

Richard L.

Enich For; Charles L. Miller, Chief

' Emergency Preparedness and Radiation Protection Branch Division of Reactor Program Management Office of Nuclear Reector Regulation Project No. 689

Attachment:

As stated cc:

See next page 1

QlSTRIBUTION:

PEPB Reading Files JRoe RSullivan i

WLycn RSullivan JGiitter RHasselberg SMagruder PUBLIC DISK / DOCUMENT NAME: C:\\EALS\\SDEAL\\9-11.LTR To rei.,elve a copy of this document, indicate in the box: "C"

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.%[%,.,/g WASHINGTON, D.C. 30666 0001 Ci4 September 11, 1998 Alan Nelson Nuclear Energy Institute 1776 Eye Street, NW, Suite 400 Washington, DC 20006-3708

Dear Mr. Nelson:

In a letter dated August 3,1998, we provided you comments on Nuclear Energy Institute's (NEl's) guidance for development of emergency action levels applicable in the shutdovJ and refueling modes of plant operation. After receipt of these comments, you requested a copy of the shutdown events and scenarios which were used in our review of NEl's guidance. In response to your request, please find attached the shutdown events and scenarios used in our review. If you have any questions regading this matter, please contact Jim O'Brien of my staff at 301-415-2919.

Sincerely, t

harles L. Miller, Chief Emergency Preparedness and Radiation Protection Branch Division of Reactor Program Management Office of Nuclear Reactor Regulation Project No. 689

Attachment:

As stated cc:

See next page

- _. _ _ _.... ~..

' Nucle:r Energy Institut),

Projict No. 689

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Lcc:

Mr. Relph Beedle Ms. Lynnette Hendricks, Director Senior Vice President Plant Support and Chief Nuclear Officer Nuclear Energy Instituto Nuclear Energy Institute Suite 400 Suite 400 17761 Street, NW 17761 Street, NW Washington, DC 20006-3708 i

Washington, DC 20006-3708 Mr. Alex Marion, Director Programs.

Nuclear Energy Institute i

Suite 400 1776 i Street, NW:

. Washington, DC 20006-3708 l

Mr. David Modeen, Director Engineering l

Nuclear Energy Institute

' Suite 400 1776 i Street, NW Washington, DC 20006-3708 i

Mr. Anthony Pietrangelo, Director

)

. Licensing Nuclear Energy Institute Suite 400 1776 i Street, NW.

Washington, DC 20006-3708 j

Mr. Nicholas J. Liparulo, Manager I

Nuclear Safety and Regulatory Activities Nuclear and Advanced Technology Division

' Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, Pennsylvania 15230 Mr. Jim Davis, Director Operations Nuclear Energy Institute Suite 400 1776 i Street, NW l

Washington, DC 20006-3708 I

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Attachment

'l NUREG-1449 SCENARIOS UTILIZED IN REVIEW OF NEI's SHUTDOWN EAL GUIDANCE I

To support the NRC's review of NEI's shutdown emergency action level (EAL) guidance, an evaluation of the classification of shutdown events reported in NUREG-1449 using the NEI guidance was performed. The NUREG-1449 scenarios were expanded (increased in severity or otherwise modified) in order to test the higher level EALs. During deliberations on the NEI EALs, an alternative set of shutdown EALs were formulated by the NRC. These EALs were provided in a letter to NEI dated August 3,1998. These alternative EALs were also evaluated using the NUREG-1449 scenarios. The results of these evaluations follow.

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j SHUTDOWN / REFUELING SCENARIOS BASED ON NUREG-1449 EVENTS SCENARIO #1 Vermont Yankee -- Loss ofInventory Event -- March 9,1989 Scenario Overview (refer to Appendix A of NUREG-1449 or LER 271/89-013 for further detail) i 220 gpm leak for 47 minutes through RHR min flow valve to suppression pool Caused about a reported 120" drop in cavity level (total of 10,300 gpm) from 290" above TAF to ~ 170" from TAF (later determined to be a 72" drop)

Leak terminated by manual closure of min flow valve Initial water level about 290" above TAF (13" below reactor vessel flange)

SD cooling isolates at 127" above TAF ECCS injection occurs at 82.5" above TAF Event Classification Actual classification: NONE Classification under new NEI EAL scheme: UE Classification under NRC EAL scheme:

UE Expanded Scenario 1-1 Condition NEI NRC INITIAL CLASSIFICATION UE UE RHR min flow valve can not be isolated SD cooling does not isolate at 127" above TAF ECCS inj does not occur at 82.5" above TAF Coolant level reaches ECCS actuation point Alert Coolant level reaches 6" below ECCS actuation Alert point Containment closure is met Coolant level reaches 6" below ECCS actuation SAE point for more than 15 minutes Coolant level drops to below TAF for > 30

• SAE minutes

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-j Coolant level drops to below TAF for longer than j

site specific time to clad damage j

The NEI scheme classification does not reac't the SAE because there is no indication that the RPV is breached (RCS is breached, i.e., through RHR, but RPV is not breached). In addition, an indication of RCS temperature >200 "F (or a calculated time to boil) is needed to meet the classification criteria i

Ernanded Scenario 1-2

' Condition NEI NRC INITIAL CLASSIFICATION UE UE j

RHR min flow valve can not be isolated SD cooling does not isolate at 127" above TAF ECCS inj does not occur at 82.5" above TAF Coolant level reaches ECCS actuation point Alert Coolant level reaches 6" below ECCS actuation Alert Containment closure is not met Coolant level reaches 6 " below ECCS actuation SAE for more than 15 minutes Coolant level drops to below TAF for > 30 SAE*

minutes Coolant level drops to below TAF for longer than GE site-specific time to clad damage (BWR) Secondary containment radiation GE*

monitors exceed safe radiation levels i

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• The NEI scheme classification does not reach the SAE or GE because there is no indication that

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. the RPV is breached (RCS is breached, i.e., through RHR, but RPV is net breached). If the RPV breach is assumed to be met then the SAE and GE would be declared at the points indicated.

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SCENARIO #2.

Diablo Canyon 2 -- Loss of shutdown Cooling --April 10,1987 Scenario Overview (refer to Appendix A ofNUREG-1449 or LER 323/87005 for further detail)

Mid loop (107' to 108'2")

RCS temp initially 87 F RCS leakpath caused a decrease in level (at 2010h)

RCS leakpath isolated (107'4") at 2122 h RHR pumps stopped due to vortexing (or cavitation) at 2125 MU from RWST to vessel initiated at 2210 h When RHR pumps started Temperature indicated 220 F Est time to bulk boiling -45 min Esi time to core uncovery (if RCS open) -- 2.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> (after loss of RHR)

If event occurrcd two days after shutdown est time to boil was.13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> and time to core uncovery with RCS open is I h)

RCS integrity was thought to exist, but in fact leak paths existed.

Event Classification Actual classification:

NONE Classification under new NEI EAL scheme UE (unless RPV break is diagnosed)

Classification under NRC EAL scheme:

UE ALERT (If RCS and containment not intact)

Exnanded Scenario 2-1 Condition NEI NRC INITIAL CLASSIFICATION UE UE RCS is an1 intact Containment closure is nut met Alert Event occurs two days after shutdown est time to boil was.13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> and time to core uncovery is Ih Boiling occurs, level decrease begins Level reaches bottom ID of RCS loop Alert Level reaches 6" bottom ID of RCS loop for > 15 SAE minutes

-e Level belcw TAF for 30 minutes

• GE

L Level below TAF for greater than the site specific GE time to clad damage k

i The NEI scheme classification does not reach the SAE or GE because there is no indication that the RPV is breached (RCS is breached, i.e., through RHR, out RPV is not breached). If the RPV breach is assumed to be met than the GE would be declared at the i

point indicated. The SAE would not occur.

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Fun==dd Scenario 2 2 Condition NEI NRC i

INITIAL CLASSIFICATION UE UE l

RCS is nelintact Containment closure h met Alert i

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Event occurs two days after shutdown est time to boil was.13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> and time to core uncovery is 1h I

Boiling occurs, level decrease begms Level reaches bottom ID.of RCS loop Alert' Level reaches 6" below bottom ID of RCS loop Level below TAF for 30 minutes

• SAE Level below TAF for greater than the site specific SAE time to clad damage Containment challenged GE The NEI scheme classification does not reach the SAE because there is no indication that the RPV is breached (RCS is breached, i.e., through RHR, but RPV is not breached). If RPV breach is assumed then the SAE would be declared at the point indicated.

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l SCENARIO #3 Washington Nuclear Power 2 - Reactor cavity draindown -- May 1,1988 Scenario Overview (refer to Appendix A ofNUREG-1449 or LER 397/88-011 for further l

detail)

Plant shutdown days RPV head on RCS leak occurred during swap of RHR loops (drained down to suppression pool) drained about 10,000 gal RHR suction isolated at scram level terminating the release Event Classification Actual classification: NONE Classification under new NEI EAL scheme: UE -

Classification under NRC EAL scheme:

UE Expanded Scenario 3-1 l

Condition NEI NRC INITIAL CLASSIFICATION UE UE RHR suction fails to isolate i

Water level drops to ECCS low low setpoint Aled ECCS initiates restoring water level Expanded Scenario 3-2 Condition NEI NRC INITIAL CLASSIFICATION UE UE RHR suction fails to isolate Water level drops to ECCS low low setpoint Alert i

ECCS fails to initiate Water level 6" below ECCS low low setpoint Alert Water level drops below TAF Water level remains below TAF for > 30 l

minutes Water level remains below TAF for > site-SAE specific time to clad damage

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i Ernanded Scenario 3 3 Condition NEI NRC INITIAL CLASSIFICATION UE UE Add to initial conditions that containment closure not in place RHR suction fails to isolate Water level drops to ECCS low low setpoint Alert ECCS fails to initiate j

Water level 6" below ECCS low low setpoint SAE Water level drops below TAF Waterlevel remains below TAF for > 30 GE minutes 1

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SCENARIO #4.

Fort Calhoun --Loss of Offsite Power Event-- February 26,1990 Scenario Overview (refer to Appendix A of NUREG-1449 or LER 397/90-006 for further detail) 9 days aRer shutdown, RCS partially filled (above mid loop) one DG OOS for maintenance Loss of power due to spurious relay actuation second DG did not load because of interlock with SD cooling pump One minute aRer LOOP the operators cleared interlock (open SD cooling pump breaker) 4 Event Classification Actual classification: NONE Classification under new NEI EAL scheme NONE (ALERT due to loss of power)

Classification under NRC EAL scheme:

NONE Expanded Scenario 4-1 Condition NEI NRC INITIAL CLASSIFICATION none none Unable to restore power RCS heats up to 200 'F (~1 hour)

UE UE RPV level decrease to bottom ID of the RCS Alen loop RPV level decrease to 6" below the bottom Alert ID of the RCS loop RPV level decrease to TAF for > 30 minutes SAE

(~3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> after loss ofpower)

Indication of Containment Challenge (e.g.,

GE explosive mixture) l i

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9 SCENARIO #5 Crystal River 3 -- Loss of Shutdown Cooling - February 2,1986 Scenario Overview (refer to Appendix A ofNUREG-1449 or LER 302/86-003 for further detail)

RHR lost for 24 minutes RPV level belowlevel of RCS pumps

_ Temperature rose from 98 to 131 (time to saturation estimated at 83 minutes) a Event Classification Actual classification:

NONE Classification under new NEI EAL scheme NONE Classification under NRC EAL scheme:

NONE Funanded Scenario 5-1 Condition NEI NRC j-INITIAL CLASSIFICATION none none initially containment not closed Unable to restore RHR RCS heats up to 200 *F (~1 hour)

UE UE RPV level decrease to bottom ID of the RCS Alert loop RPV level decrease to 6" below the bottom Alert ID of the RCS loop RPV level decrease to 6" below the bottom SAE ID of the RCS loop for >15 minutes RPV level decrease to TAF for > 30 minutes GE i

Expanded Scenario 5-2 Conditioa NRC NEI INITIAL CLASSIFICATION none none initially containment and RCS not closed Unable to restore RHR RCS heats up to 200 *F (~1 hour)

UE UE

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P Time'to recover RHR exceeds 30 minutes Alert RPV level decrease to bottom ID of the RCS Alert loop RPV level decrease to 6" below the bottom ID of the RCS loop RPV level decrease to 6" below the bottom SAE i

ID of the RCS loop for >l5 minutes RPV level decrease to TAF for > 30 minutes OE 1

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4 SCENA.RIO #6 Waterford 3 -- Loss ofInventory -- July 14,1986 Scenario Overview (refer to Appendix A ofNUREG-1449 or LER 397/88-011 for funher detail)

Midloop RCS leak started at 0113 i

RHR pump cavitated and secured at 0317 LPSI start (600 gpm) at-0350 CETindicated 223 F RHR pumpsjogged for ~ 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />... RHR restored 0658 Event Classification Actualclassification: NONE

' Classification under new NEI EAL scheme UE Classification under NRC EAL scheme:

UE (no expanded scenarios evaluated) l 1

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SCENARIO #7 Braidwood 1 -- Loss ofInventory -- December 1,1989 l

Scenario Overview (refer to Appendix A ofNUREG-1449 or LER 397/88-011 for further detail) cold shutdown... rx pressure 350 psig, T 170 F, about to draw a bubble

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RHR reliefvalve opened at ~ 400 psig a

level decrease below the pressurizer level.... rx vessel level indicated 100 %

leakage greater than charging pump capacity Event Classification Actual classification: ALERT Classification under new NEI EAL scheme UE Classification under NRC EAL scheme:

UE (no expanded scenarios evaluated) i I

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i SCENARIO #8 Susquehanna 1 -Loss of Shutdown Cooling -- February 3,1990 Scenario Overview (refer to Appendix A of NUREG-1449 or LER 39790-006 for further detail)

.l Head on

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Containment Intact l

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RCS T = 125 F at 1555, RHR shuts down

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RCS T = 188 F at 1725, RHR restoration fails (90 min)

RCS T = 200 F at 1753 (118 min)

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RCS T = 230 F, pressure = 10 psig at 1840 (165 min)

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RHR restored at 2240 - (385 min)

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Event Classification

- Actualclassification: ALERT Classification under new NEI EAL scheme - UE Classification under NRC EAL scheme:

UE (no expanded scenarios evaluated) i i

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