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| number = ML17037C242
| number = ML17037C242
| issue date = 04/09/1974
| issue date = 04/09/1974
| title = Nine Mile Point Unit 1 - Letter Responding to the November 30, 1973 Letter Concerning the Extent and Consequences of Possible Inverted Poison Tubes in the Control Blades and Requiring Further Action Be Implemented within 15 Days After Recei
| title = Letter Responding to the November 30, 1973 Letter Concerning the Extent and Consequences of Possible Inverted Poison Tubes in the Control Blades and Requiring Further Action Be Implemented within 15 Days After Receipt of Letter
| author name = Skovholt D J
| author name = Skovholt D
| author affiliation = US Atomic Energy Commission (AEC)
| author affiliation = US Atomic Energy Commission (AEC)
| addressee name = Schneider R R
| addressee name = Schneider R
| addressee affiliation = Niagara Mohawk Power Corp
| addressee affiliation = Niagara Mohawk Power Corp
| docket = 05000220
| docket = 05000220
Line 15: Line 15:


=Text=
=Text=
{{#Wiki_filter:DocketNo.50-220HiagaxaMohawkPowerCorporation ATTN:Hr.R.R.Schneider VicePxesidont
{{#Wiki_filter:Docket No. 50-220 Hiagaxa Mohawk Power Corporation ATTN:
-ElectricOperations 300ErieBoulevard PestSyracuse, NewYork13202Gentlemen:
Hr. R. R. Schneider Vice Pxesidont - Electric Operations 300 Erie Boulevard Pest
APRg)g74Distribution DocketFileAECPDR.LocalPDRBranchReadingJRBuchanan, ORNLDJSkovholt, L:ORTJCarter, L:ORACRS(16)RO(3)OGCDLZiemann, L:ORBif/2CJDeBevec, L:ORBII2JLSapir,L:ORB//2RH)iggs,L:ORBII2SVarga,L:RPInaletterdatedNovember30,1973,yousubmitted information concerning theextentandconsequences ofpossibleinvertodpoisontubesinthecontrolbladesoftheNineMilePointUnit1reactor.Hehavereviewedyoursubmittal alongwiththeassociated GeneralElectricgenericsub-mittaldatedOctober8,1973,andhaveconcluded thatwithoutadditional supporting evidencetheassumption ofahomogeneous dofectrateof5Xisnot)ustified.
: Syracuse, New York 13202 Gentlemen:
Inaddition, relatively smallgroupings ofdefective bladescanpxoducethemaximumundesirable effects.Therefore, tomaintainthecurrentsafetymarginrequirements untilaninspection ofthexodsisperformed, wearerequiring thatthefollowing actionbeimplemented within15daysafterreceiptofthisletter.1.Subtractavalueof0.2Xdeltakfromthecurrentallowable insequence controlrodreactivity worth.2.Addavalueof10psitothemaximumpressurecalculated forthesafetyvalvesizingpressurization transient andconfirmthatadequatemarginexists.3.Establish aprocedure toreportanyobservedreactivity anomalygreaterthan0.5XtotheAECwithin10daysoftheobservation.
APR g )g74 Distribution Docket File AEC PDR.
Itisimportant thatuncertainties associated withthepossiblepresenceofdefective controlbladesbeeithersignificantly reducedoxeliminated assoonaspracticable.
Local PDR Branch Reading JRBuchanan, ORNL DJSkovholt, L:OR
Youshould,therefore, inspectahomogeneous samplingofabout50Xormoreofthecontrolrodsduringthenextrefueling outageandcompletetheinspection oftheentirecorewithinthenexttworefueling outages.
: TJCarter, L:OR ACRS (16)
llIII NiagaraMohawkPowerCorporation APRg797yIfthecalculated potential shutdmmmarginloss(assuming fullsettlinginalltheobservedinvertedpoisontubes)extrapolated toincludeuninspected rodsislessthan0.5Xdeltak,addthecalculated valueto0.25/deltaktoobtaintheminimumshutdownmarginrequirement forthefollowing fuelcycle.Youmayxeducetheminimumshutdownmarginrequire-mentsbythecalculated xeactivity uncertainty removedbythereplacement.
RO (3)
ofdefective blades.Iftheresultsoftheinspection yieldapotenti.al equivalent full-core shutdownmarginlossgreaterthan0.51deltak,inspection resultsshouldbesubmitted totheAECforreviewbefoxetheendoftheoutageandsomeamountofbladereplacement mayberequired.
OGC DLZiemann, L:ORB if/2 CJDeBevec, L:ORB II2
Basedupontheinspection x'esultsandanybladereplacements, subsequent restrictions oninsequence contxolrodxeactivity worthsandpressuremarginswillbead)ustedtoreflectknowncoreconditions.
: JLSapir, L:ORB //2 RH)iggs, L:ORB II2
Intheinterim,westronglyencourage theperformance of-aninservice inspection ofcontrolrodsduringanyshutdownofsignificant durationbeforeyournextrefueling outage.Sincerely, DonaldJ.SkovholtAssistant DirectorforOperating ReactorsDirectorate ofLicensing cc:J.BruceHacDonald, EsquireDeputyComnd.ssioner andCounselNewYorkStateDepartment ofCommerce-andCounseltotheAtomicEnergyCouncil99Washington AvenueAlbany,NewYork12210AxvtnZ.Upton,EsquireLeBoeuf,Lamb,Leiby5HacRae1757NStreet,N.W.Washington, D.C.20036Dr.WilliamGeymouxStaffCoordinator NewYorkStateAtomicFnergyCouncilNewYorkStateDepartment ofCommerce112StateStreetAlbany,NewYork12207Anthony?'.Roisman,EsquireBerlin,RoisnanandKessler1712NStreet,N.W.Washington, D.C.20036OswegoCi.tyLibraryX740YSURHAM23v'ATCW L:ORB//JLSapir:sg4/8/74L:ORBI/CJDeBcIJgP~L:0DLZiemann c,lflwL:0DJoholt4//7'4PormhEC-3ld(Rev.9.33)hECM0240CI'0CA2IO1IA00I$20204 lC=}}
: SVarga, L:RP In a {{letter dated|date=November 30, 1973|text=letter dated November 30, 1973}}, you submitted information concerning the extent and consequences of possible invertod poison tubes in the control blades of the Nine Mile Point Unit 1 reactor.
He have reviewed your submittal along with the associated General Electric generic sub-mittal dated October 8, 1973, and have concluded that without additional supporting evidence the assumption of a homogeneous dofect rate of 5X is not )ustified.
In addition, relatively small groupings of defective blades can pxoduce the maximum undesirable effects.
Therefore, to maintain the current safety margin requirements until an inspection of the xods is performed, we are requiring that the following action be implemented within 15 days after receipt of this letter.
1.
Subtract a value of 0.2X delta k from the current allowable insequence control rod reactivity worth.
2.
Add a value of 10 psi to the maximum pressure calculated for the safety valve sizing pressurization transient and confirm that adequate margin exists.
3.
Establish a procedure to report any observed reactivity anomaly greater than 0.5X to the AEC within 10 days of the observation.
It is important that uncertainties associated with the possible presence of defective control blades be either significantly reduced ox eliminated as soon as practicable.
You should, therefore, inspect a homogeneous sampling of about 50X or more of the control rods during the next refueling outage and complete the inspection of the entire core within the next two refueling outages.
 
ll II I
 
Niagara Mohawk Power Corporation
- 2 APR g 797y If the calculated potential shutdmm margin loss (assuming full settling in all the observed inverted poison tubes) extrapolated to include uninspected rods is less than 0.5X delta k, add the calculated value to 0.25/ delta k to obtain the minimum shutdown margin requirement for the following fuel cycle.
You may xeduce the minimum shutdown margin require-ments by the calculated xeactivity uncertainty removed by the replacement.
of defective blades.
If the results of the inspection yield a potenti.al equivalent full-core shutdown margin loss greater than 0.51 delta k, inspection results should be submitted to the AEC for review befoxe the end of the outage and some amount of blade replacement may be required.
Based upon the inspection x'esults and any blade replacements, subsequent restrictions on insequence contxol rod xeactivity worths and pressure margins willbe ad)usted to reflect known core conditions.
In the interim, we strongly encourage the performance of-an inservice inspection of control rods during any shutdown of significant duration before your next refueling outage.
Sincerely, Donald J. Skovholt Assistant Director for Operating Reactors Directorate of Licensing cc:
J. Bruce HacDonald, Esquire Deputy Comnd.ssioner and Counsel New York State Department of Commerce -and Counsel to the Atomic Energy Council 99 Washington Avenue Albany, New York 12210 Axvtn Z. Upton, Esquire LeBoeuf, Lamb, Leiby 5 HacRae 1757 N Street, N. W.
Washington, D. C.
20036 Dr. William Geymoux Staff Coordinator New York State Atomic Fnergy Council New York State Department of Commerce 112 State Street Albany, New York 12207 Anthony ?'. Roisman, Esquire Berlin, Roisnan and Kessler 1712 N Street, N. W.
Washington, D. C.
20036 Oswego Ci.ty Library X740Y SURHAM23v'ATCW L:ORB //
JLSapir: sg 4/8/74 L:ORB I/
CJDeB c
IJ gP~
L:0 DLZiemann c,lf lw L:0 DJ o holt 4/
/7'4 Porm hEC-3ld (Rev. 9.33) hECM 0240 CI'0 CA2 IO 1IA00 I
$20 204
 
l C=}}

Latest revision as of 14:55, 9 January 2025

Letter Responding to the November 30, 1973 Letter Concerning the Extent and Consequences of Possible Inverted Poison Tubes in the Control Blades and Requiring Further Action Be Implemented within 15 Days After Receipt of Letter
ML17037C242
Person / Time
Site: Nine Mile Point 
Issue date: 04/09/1974
From: Skovholt D
US Atomic Energy Commission (AEC)
To: Schneider R
Niagara Mohawk Power Corp
References
Download: ML17037C242 (4)
v • d • e


Text

Docket No. 50-220 Hiagaxa Mohawk Power Corporation ATTN:

Hr. R. R. Schneider Vice Pxesidont - Electric Operations 300 Erie Boulevard Pest

Syracuse, New York 13202 Gentlemen:

APR g )g74 Distribution Docket File AEC PDR.

Local PDR Branch Reading JRBuchanan, ORNL DJSkovholt, L:OR

TJCarter, L:OR ACRS (16)

RO (3)

OGC DLZiemann, L:ORB if/2 CJDeBevec, L:ORB II2

JLSapir, L:ORB //2 RH)iggs, L:ORB II2
SVarga, L:RP In a letter dated November 30, 1973, you submitted information concerning the extent and consequences of possible invertod poison tubes in the control blades of the Nine Mile Point Unit 1 reactor.

He have reviewed your submittal along with the associated General Electric generic sub-mittal dated October 8, 1973, and have concluded that without additional supporting evidence the assumption of a homogeneous dofect rate of 5X is not )ustified.

In addition, relatively small groupings of defective blades can pxoduce the maximum undesirable effects.

Therefore, to maintain the current safety margin requirements until an inspection of the xods is performed, we are requiring that the following action be implemented within 15 days after receipt of this letter.

1.

Subtract a value of 0.2X delta k from the current allowable insequence control rod reactivity worth.

2.

Add a value of 10 psi to the maximum pressure calculated for the safety valve sizing pressurization transient and confirm that adequate margin exists.

3.

Establish a procedure to report any observed reactivity anomaly greater than 0.5X to the AEC within 10 days of the observation.

It is important that uncertainties associated with the possible presence of defective control blades be either significantly reduced ox eliminated as soon as practicable.

You should, therefore, inspect a homogeneous sampling of about 50X or more of the control rods during the next refueling outage and complete the inspection of the entire core within the next two refueling outages.

ll II I

Niagara Mohawk Power Corporation

- 2 APR g 797y If the calculated potential shutdmm margin loss (assuming full settling in all the observed inverted poison tubes) extrapolated to include uninspected rods is less than 0.5X delta k, add the calculated value to 0.25/ delta k to obtain the minimum shutdown margin requirement for the following fuel cycle.

You may xeduce the minimum shutdown margin require-ments by the calculated xeactivity uncertainty removed by the replacement.

of defective blades.

If the results of the inspection yield a potenti.al equivalent full-core shutdown margin loss greater than 0.51 delta k, inspection results should be submitted to the AEC for review befoxe the end of the outage and some amount of blade replacement may be required.

Based upon the inspection x'esults and any blade replacements, subsequent restrictions on insequence contxol rod xeactivity worths and pressure margins willbe ad)usted to reflect known core conditions.

In the interim, we strongly encourage the performance of-an inservice inspection of control rods during any shutdown of significant duration before your next refueling outage.

Sincerely, Donald J. Skovholt Assistant Director for Operating Reactors Directorate of Licensing cc:

J. Bruce HacDonald, Esquire Deputy Comnd.ssioner and Counsel New York State Department of Commerce -and Counsel to the Atomic Energy Council 99 Washington Avenue Albany, New York 12210 Axvtn Z. Upton, Esquire LeBoeuf, Lamb, Leiby 5 HacRae 1757 N Street, N. W.

Washington, D. C.

20036 Dr. William Geymoux Staff Coordinator New York State Atomic Fnergy Council New York State Department of Commerce 112 State Street Albany, New York 12207 Anthony ?'. Roisman, Esquire Berlin, Roisnan and Kessler 1712 N Street, N. W.

Washington, D. C.

20036 Oswego Ci.ty Library X740Y SURHAM23v'ATCW L:ORB //

JLSapir: sg 4/8/74 L:ORB I/

CJDeB c

IJ gP~

L:0 DLZiemann c,lf lw L:0 DJ o holt 4/

/7'4 Porm hEC-3ld (Rev. 9.33) hECM 0240 CI'0 CA2 IO 1IA00 I

$20 204

l C=

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