ML20065K214

Application for Amend to License NPF-86,deleting Requirement to Perform Weekly Stroke Test of High Pressure TCV

ML20065K214
Person / Time
Site:	Seabrook
Issue date:	11/13/1990
From:	Feigenbaum T PUBLIC SERVICE CO. OF NEW HAMPSHIRE
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20065K219	List: ML20065K214 ML20065K227
References
NYN-90196, NUDOCS 9011160138
Download: ML20065K214 (4)

Text

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m. ., _x. .

h" JNew Hompshire- .

1. Ted C. Feigenboom i

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h hh President and Chief Executive Officer g

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'h _ . NYN 90196

, y November 13, 1990 Q i 4'

LUnited States Nuclear Regulatory Ccmmission

• 1 . Washington, D.C. 20555 s '

, ' L Attention: ' Document Control' Desk

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References:

- a) Facility Operating License No. NPF 86, Docket No. 50 443 i s '

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o b) PSNH Letter' SBN 617 dat;d January 30,.1984, "Seabrook Station (i

i. Probabilistic Safety . Assessm< nt Main Report and Summary Report *,

, A ,' J. DeVincentis to G. W. Knighton .

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Subject:

Request fora License Amendment: Turbine Overspeed Protection System 0 Surveillance Frequent, 1

L O'entlemen:

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C. . . , yPursuaint t'oi10 CFR 50.90, New Hampshire Yankee (NHY) hereby proposes to amend

([ . > tthe' Seabrook Station' Operating License (Facility Operating License NPF 86) by incorporating- ,

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-the.jproposed changes,' provided. herein as Enclosure 1,'. into the Seabrook Station Technical .

R 1SpecificationsOThese. proposed changes delete the requirement- to perform a weekly stroke t itest of the?high pressure turbine control valves. The Surveillance Requirements for the high - i

pressure turbine stopl valves and the combined =interme'diate valves are unchanged,~ as is the  !

K monthly stroke. test requirement for the highLpressure turbine control, valves. - Additionally, editorialf changes with respect to';valvec nomenclature have been indicated to provide' N.> , consistency' throughout the Technical Speelfication.

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gThe basis for this proposed change is provided in Enclosure 2, which includes a safety ,

evaluationiof the propcsed changes. Based upon the information contained 1in Enclosure 2,  ;

, NHY has; concluded that the proposed change does not involve an Unreviewed Safety 1 LQuestion' pursuant to 10 CFR '50.59, nor does it involve a Significant Hazards Consideration 1

, ' pursuant to 110 CFR 50.92.

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. " ,e lla.mpshite-Yankee' has reviewed the proposed . change in' accordance with the

' crito ecifiedcin 10 CFR150.92 and has determined that the proposed change would not: 3

,p 1; involve a significant increase in the probability or consequences of any accident previously evaluated. . The Seabrook Station Probabilistic Safety Assessment yy ,

(SSPSA) [ Reference (b)] estimates the frequency of turbine missile generation y

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%%ompshire Yankee DSision of Public Service Company of New Hampshire l

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? P.O. Box 300

• Seabrook, NH 03874

• Telephone (603) 474 9521 hdel 9

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J, L' United States Nuclear Regulatory Commitsien November 13, 1990 .f l Attention: Document Control Desk' Page two i

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and its consequences. This conservative analysis demonstrates that the risk to

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public health and safety from turbine missiles is negligible. The SSPSA turbine missile generation estimates are based on statistical and analytical data which d" ';"~.

show a relatively small. contribution by overspeed failures versus failures at >

operating- speed. Given that the generation of turbine missiles is not very

. ,r sensitive to changes in control system reliability, the extension of the testing frequency-- for the high pressure turbine control valves will not cause a :

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s ignificant _ increase in the probability of core damage or radiological j consequences from turbine missiles.' Also, the in series stop valves which are hA yio tested on a weekly basis provide additional overspeed protection. Redundant isolation. capabilities to prevent turbine overspeed are also provided by the main steam isolation valves. Extending the frequency of testing _ the high

_% l 7 . pressure turbine control valves reduces the aumber of power reductions i Oli , . required to perform this testing and reduces the risk of inadvertent turbine trip

%Q ' (and reactor trip) caused by such testing.

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ji' $ C 2. Create: the possibility - of a new or - different kind of accident from any- ,

previously evaluated. The analyses presented in FSAR Section{15.1 and 15.2

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I N*Y . bound the two possible failure mechanisms which exist for the h,gh pressure turbine control valves (ie., .the possibilityiof a1contr01 valve not closing in

, . _ conjunction with .a stop valve not. closing, or spurious. control valve closure).

W, The extension of the testing frequency from weekly to-monthly does not create

,w a new failure mechanism; therefore, the possibility of a new or different kind g; of accident is not created.:

3. 'Involvet a significant_ reduction in a margin of safety. Margin of safety as it .

relates to the protection of_ safety related structures, systems and components

, from turbine missiles is; measured in _ terms of!t he probabinty of radiological ,

U s . consequences exceeding 10CFR100_ limits.' ' FSAR Section 3.5.1.3 specifies the

. acceptance < criteria "and;analyticalLresults for the probability that a turbine

= missile is generated! and strikesl ai safety 7related area which' may lead to.

consequenecs exc'eeding 10 CFR 100 limits. Additionally, the Seabrook Station M

Probabilistic Safety Assessment (SSPSA)- quantifies turbine missile demage frequencies for'several co'n. mon cause initiating events. 'The SSPSA~ analysis

demon'strates that the probability of core damage frm turbine missiles provides o 3 -negligible contribution to public risk. The SSPSA turbine missile generation estimates.are based on- statistical and analytical data which show a relatively j  : small contribution by overspeed failures -versus failures at operating speed, .

therefore, damage frequencies would be further reduced if only turbine missiles. ,

, generated as ~a result of overspeed wete considered. Given that the generation

<.' of turbine misslics is not very sensitive to changes in control system n ibbility, the extension'of.the testing frequency for the high pressure turbine control  ;

valves does not significantly increase turbine missile damage frequencies and

• therefore does not result in a significant decrease .in the margin of safety, e

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- United States Nuclear Regulatory Commission November 13, 1990 Attention: Document Control Desk . Page three Performance of this surveillance - testing requires that power be reduced to approximately 93% of rated thermal power. Extending the frequency of this testing yields ,

c;onomic benefits associated with the reduced numbst of power reductions and reduces the -;

r,robability of an inadvertent turbine trip (and reactor trip) caused by testing, it is requested that the NRC complete its review of this license amendment request by January 11, 1991.- If- you have any questions regarding this request, please contact Mr. Terry L.

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liarpster, NIIY Director of Licensing Services, at (603) 474 9521, extension 2765.  !

Very truly yours,.

.,gng y z,&

Ted C. Feig nbaum Enclosurc(s)

TCF:RRB/ tad /ss!'

cc: Mr. Thomas T. Martin Regional . Administrator United States Nuclear Regulatory Commission Region I

-475 Allendale Road King of Prussia. PA 19406 Mr. George L. Iversor., Director

. Office of Emergency Management State Office Park South 107 Pleasant Street Concord,' NI-I 0~3 301 Mr. Victor Nerses, Sr. Project Mgr.

Project Directorate I 3 -

Division of Reactor Projects U. S. Nuclear Regulatory Commission Washington, DC 20555 Mr. Noel Dudley NRC Senior Resident inspector P.O. Box 1149 Scabrook, NH 03874 i

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• New llampshire Yankee November 13, 1990  ;

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ENCI.OSURE 1 TO NYN . 90196 p.

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