ML20133J468

Discusses 961114 AEOD Presentation of Assessment of Spent Fuel Cooling Viewgraph 13, Reduced Time to Boil at Nine Mile Point Unit 2, & Forwards Figures

ML20133J468
Person / Time
Site:	Nine Mile Point
Issue date:	01/13/1997
From:	Thompson H NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:	Rogers K NRC COMMISSION (OCM)
References
NUDOCS 9701210028
Download: ML20133J468 (8)

Text

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',e g 4 UNITED STATES

• E NUCLEAR REGULATORY COMMISSION i f WASHINGTON, D.C. 2055M001

%*****/ January 13, 1997 i

i l

MEMORANDUM TO:

Cyissi r Rog s

]

FROM: _h .;T hon, Jr.

Acting 15 cutive Director for Operations

SUBJECT:

TIMES TO INITIATION OF BOILING SUBSEQUENT TO LOSS OF SPENT FUEL COOLING i

During the AEOD presentation of its assessment of spent fuel cooling on November 14, 1996, you raised questions about Viewgraph 13, " Reduced Time to Boil at Nine Mile Point l Unit 2." Of particular interest was the apparent lack of smoothness in the plot of hours to boil as a function of outage number. You also indicated that you were interested in seeing l the plot of time to boil versus time after reactor shutdown. l The data plotted in Viewgraph 13 (attached) were provided by the Nine Mile Point Unit 2 licensee in a June 14,1996, memorandum and discussed during a June 21,1996, telephone conversation with AEOD staff. In response to discussions with AEOD after the November 14,1996, Commission meeting, Nine Mile Point Unit 2 re-evaluated their spent fuel pool heatup calculations and found that there were some anomalies in the data that had been provided in June 1996. The original calculations supplied in June 1996 were inconsistent. The original calculations for refueling outages 1,2 and 3 assumed that the refueling pool gates were not installed (" gates out" configuration). The original calculations for refueling outage 4 assumed that the refueling pool gates were installed

(" gates in" configuration). Note that when the refueling pool gates are installed they separate the fuel pool from the reactor cavity. When the refueling pool gates are not i installed, there is a larger mass of water to be heated, i.e., the water in the spent fuel pool and the water in the reactor cavity. The data provided in June 1996 were further complicated because the calculated time to boil for the first refueling outage included the offects of environmental heat losses while the calculated times to boil for the other three i outages did not incluue mese effects.

The attached figures provide consistent results of the Nine Mile Point Unit 2 reanalyses noting the positions o' the refueling pool gates and neglecting environmental heat losses. ,

Figure 1 shows the time until boiling begins versus the number of days after reactor shutdown. We believe this figure addresses the request you made on November 14, 1996, during the AEOD spent fuel cooling presentation. This figure also shows the effect

) 1 i

of the refueling pool gates' positions.

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CONTACT: Harold L. Ornstein, AEOD/SPD/RAB

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415 7574 17001'o N i 9

gotafogas goga  % E ECULJJORY CENTRAL RLE5 [N i PDit M ,

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Commissioner Rogers

• l Figure 2 shows the time from reactor shutdown until completion of the full core offload.

Note that this is different than the information provided in Viewgraph 13 which indicated time from reactor shutdown until start of core offload. As Figure 2 indicates, the period l from shutdown until completion of the offload decreased from 35 days in the first outage l

to 13 days in the fourth refueling outage. j Figure 3 shows the time to initiate boiling as a function of outage number with the

refueling pool gates in and out. During the first four refueling outages the refueling pool gates were out at Nine Mile Point Unit 2. However, if maintenance work would have been required on the reactor vessel or appurtenances during those times it would have been l necessary to have the refueling pool gates installed, thereby leading to shorter times to

spent fuel pool boiling.

These figures will be accompanied by explanatory text in the AEOD report when it is j finalized for publication as a NUREG report.

Attachments: Viewgraph 13 " Reduced Time to Boil at Nine Mile Point Unit 2"  !

Figure 1 " Time to Boil vs. Time Af ter Reactor Shutdown"

, Figure 2 " Full Core Offload Times vs. Outage Number" Figure 3 " Time to Boil vs. Outage Number" cc w/ atts.:

Chairman Jackson Commissioner Dieus Commissioner Diaz Commissioner McGaffigan SECY j OCA

OPA OGC Distribution w/atts.

GIARft#T* KRaglin SMeador (AEOD 96-103)

SPD R/F FCongel (SPD 96-81)

AEOD R/F PBaranowsky t File _.Conter J' l

OEDO R/F (WITS 9600190) JMitchell, OEDO Public DOCUMENT NAME: C:WP51\WPDOCS\SFP\CROGERS.HLO

'See previous concurrence:

T. e.cw . ,, .: thi. e.c.n..t. ine.. in th. bec c . copy without .es. chm.nt/.ncio.ur. t - Copy with .tt. chm.nt/.nclosur.

ic . u..opy _ >M OFFICE RAB E D:SPD E AD:AEOD DEDOf,j y A:E 7/

NAME HOrnstein:mmk CRossi Dross EJoshin ljiThompson DATE 12/23/96* 01/08/97* 01/ /97 01//f97 / 01//g/97 OFFICIAL RECORD COPY ' '

i

)

Commissioner Rogers /

/

Figure 2 shows the time from reactor shutdown until completion of th ull core offload.

Note that this is different than the information provided in Viewgrap 13 from the November 14 Commission briefing which indicated time from reac r shutdown until start of core offload. As Figure 2 indicates, the period from shutdow unti! completion of the offload decreased from 35 days in the first outage to 13 days the fourth refueling outage.

Figure 3 shows the time to initiate boiling as a function outage number with the refueling pool gates in and out. During the first four r ueling outages the refueling pool gates were out at Nine Mile Point Unit 2. However, maintenance work would have been required on the reactor vessel or appurtenances du g those times it would have been necessary to have the refueling pool gates install , thereby leading to shorter times to spent fuel pool boiling.

These figures will be accompanied by explan tory text in the AEOD report when it is finalized for publication as a NUREG report.

Attachments: Viewgraph 13 " Reduc d Time to Boil at Nine Mile Point Unit 2" Figure 1 " Time to Bo' vs. Time After Reactor Shutdown" Figure 2 " Full Core ffload Times vs. Outage Number" Figure 3 " Time to oil vs. Outage Number" cc w/ atts.:

Chairman Jackson Commissioner Dicus Commissioner Diaz Commissioner McGaffig SECY OCA OPA OGC Distribution w/at s.:

RAB R/F KRaglin SMeador (AEOD 96-103)

SPD R/F FCongel (SPD 96-81)

AEOD R/F PBaranowsky File Center OEDO R/F ( ITS 9600190) JMitchell, OEDO Public DOCUMEN, NAME: C:WP51\WPDOCS\SFP\CROGERS.HLO

'See previous concurrence:

To receiv py of this document, indicate in the box: "C" s Copy w attachment / enclosure "E" = Copy wth attachment / enclosure OFFICE RAB lE D:SPD E AQAfp0 DEJOg,{- A:EDO NAME HOrnstein:mmk CRossi DRgr/ Ey6Mpti HThompson DATE 12/23/96* 01/08/97* 01/N97 01rf/97 01/ /97 OFFICIAL RECORD COPY

. _ = - .- . -- - _ - _ _ _ - - _ . - - - -- - - . . ...

i l

I Commissioner Rogers l l

l l' Figure 2 shows the time from reactor shutdown until completion of the full core offload.

Note that this is different than the information provided in Viewgraph 13 from the

] November 14 Commission briefing which indicated time from reactor shutdown until start d

of core offload. As Figure 2 indicates, the period from shutdown until cempletion of the offload decreased from 35 days in the first outage to 13 days in the fourth refueling outage. '

Figure 3 shows the time to initiate boiling as a function of outage number with the refueling pool gates in and out. During the first four refueling outages the refueling pool gates were out at Nine Mile Point Unit 2. However, if maintenance work would have been

required on the reactor vessel or appurtenances during those times it would have been

! necessary to have the refueling pool gates installed, thereby leading to shorter times to spent fuel pool boiling.

1

These figures will be accompanied by explanatory text in the AEOD report when it is finalized for publication as a NUREG report.

j Attachments: Viewgraph 13 " Reduced Time to Boil at Nine Mile Point Unit 2" Figure 1 " Time to Boil vs.~ Time After Reactor Shutdown" l Figure 2 " Full Core Offload Times vs. Outage Number" Figure 3 " Time to Boil vs. Outage Number"

]

cc w/ atts.:

f Chairman Jackson Commissioner Dicus Commissioner Diaz /

Commissioner McGaffigan SECY y i OCA OPA j OGC

/

Jistribution w/atts.: 3%let. q RAB R/F KRaglin LRaines (AEOD 96-103)

SPD R/ FCongel yohrer (SPD 96-81Q AEO R/F PBaranowsky File Center OE R/F (WITS 9600190) JMitchell, OEDO Public D CUMENT NAME: C:WP51\WPDOCS\SFP\CROGERS.HLO i To receive a copy of this document, Indicate in the box: "C"

• Copy without attachment / enclosure "E" a Copy with attachment / enclosure "N" s No copy i OFFICE RAB 4//> E D:SPD lg AD:AEOD DEDO l A:EDO l NAME HOrnstein:mmk CRqsggf( Dross EJordan HThompson DATE 12/zs796 01/<J/97 ~ ' 01/ /97 01/ /97 01/ /97 OFFICIAL RECORD COPY

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Reduced Time to Boil i at Nine Mile Point Unit 2 i

i 108 i o HOURS TO BOIL ,

5 DAYS TO OFFLOAD i 23 39 13 29 7 i 8

M 1 2 3 4 Outage Number (Viewgraph 13)

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Days After Reactor Shutdown to Full Core Offload Figure 1 Time to Boil vs. Time After Reactor Shutdown

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$ 15 13 0-i 1 2 3 4 REFUEL OUTAGE NUMBER I

Figure 2 Full Core Offload Times vs. Outage Number

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REFUEL OUTAGE NUMBER 1

) Figure 3 Time to Boil vs. Outage Number

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