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

4 q

m..,

_x.

h" JNew Hompshire-Ted C. Feigenboom h

hh

?

i President and Q

Chief Executive Officer g

1 7

1

'h NYN 90196 y

Q November 13, 1990 i

4' LUnited States Nuclear Regulatory Ccmmission

. Washington, D.C.

20555 1

s

' L Attention:

' Document Control' Desk

+

i

References:

- a)

Facility Operating License No. NPF 86, Docket No. 50 443 i

s

li b)

PSNH Letter' SBN 617 dat;d January 30,.1984, "Seabrook Station

(

o i.

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

i A,'

J. DeVincentis to G. W. Knighton.

.3 f

Subject:

Request fora License Amendment:

Turbine Overspeed Protection System 0

Surveillance Frequent, 1

L O'entlemen:

x 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-fy

-the.jproposed changes,' provided. herein as Enclosure 1,'. into the Seabrook Station Technical 1 pecificationsOThese. proposed changes delete the requirement-to perform a weekly stroke S

t R

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.

.y w.

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.

I W

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

' 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

9011160138 901113 u

w PDR ADOCK 05000443 P

PDC

.i

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

m

? P.O. Box 300

• Seabrook, NH 03874

• Telephone (603) 474 9521 hdel l

- w 9

m2

'~

p i

%

• gi

j'-

y3 2

.f J,

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

g

I and its consequences. This conservative analysis demonstrates that the risk to 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 sensitive to changes in control system reliability, the extension of the testing

,r frequency-- for the high pressure turbine control valves will not cause a :

~ ignificant _ increase in the probability of core damage or radiological j

s consequences from turbine missiles.' Also, the in series stop valves which are hA tested on a weekly basis provide additional overspeed protection. Redundant yio 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.

m4 ! w.

ji' $ C 2.

Create: the possibility - of a new or - different kind of accident from any-

@g. N

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

. 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! he probabinty of radiological t

U

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

. 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

-negligible contribution to public risk. The SSPSA turbine missile generation o

3 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

'j 4

I

.h fl Y

i

' - 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.

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

Very truly yours,.

.,gng z,&

y 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~ 301 3

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

.I

,,p.

- 4 j

i.

1 1

-1 4

New llampshire Yankee j

November 13, 1990 O'

l i

.e s t'

l

?.

=>

ENCI.OSURE 1 TO NYN. 90196 p.

I L

f

. h..

6 I

.I

?

df 5 gr

' [I

==

3 4

---