PLA-1902, Interim Deficiency Rept Re Isolation of Nitrogen Makeup Sys. Also Reportable Per Part 21.Initially Reported on 830912. Permanent Design Mod Will Be Implemented.Final Rept Will Be Submitted in Dec 1983

Interim Deficiency Rept Re Isolation of Nitrogen Makeup Sys. Also Reportable Per Part 21.Initially Reported on 830912. Permanent Design Mod Will Be Implemented.Final Rept Will Be Submitted in Dec 1983

ML20090H422
Person / Time
Site:	Susquehanna, North Anna
Issue date:	10/10/1983
From:	Curtis N PENNSYLVANIA POWER & LIGHT CO.
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
REF-PT21-83 10CFR-050.55E, 10CFR-50.55E, PLA-1902, NUDOCS 8310280139
Download: ML20090H422 (5)

Text

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PPaL Pennsylvania Power &' Light Company Two North Ninth Street

• Allentown, PA 18101

• 215 / 770'5151 Norman W. Curtis Vice President-Engineering & Construction-Nuclear 215/770-7501 October 10, 1983

' Dr. '1htsnas E. Phlrley Acting Regional Administrator, Region I U. S. Nuclear Regulatory Cm mission 631 Park Avenue King of Prussia, PA 19406 SUSQUEHANNA STEAM ELECIRIC STATI m - UNIT 2 INI'ERIM REPORT OF A DEFICIENCY CWCERNING ISCIATICN OF THE UNIT 2 NITROGEN MAKEUP SYSTEM E". 100508 FILE 821-10 PIA-1902

Dear Dr. Murley:

This letter serves to provide the Cmmission with an interim report on a deficiency concerning isolation of the Unit 2 Nitrogen Makeup Syst s. This deficiency was originally reported by telephone to Mr. E. C. McCabe of NRC Region I on Septaber 12, 1983 by Mr. J. Saranga of PP&L as reportable under the requirments of 10CFR50.55(e) for SSES Unit 2. This cordition was reported to the Camission for Unit 1 in a letter (PIA-1842) dated 9/13/83 which transmitted Licensee Event Report No.83-043.

The attachment to this letter contains a description of the deficiency, its cause, and the safety inplications.- Corrective action will include a permanent design modification to the Nitrogen Makeup Systs. PP&L anticipates providing the Cmmission with a final report in December,1983, including the corrective action taken or planned. This information is furnished for Unit 2 pursuant to the provisions of 10CFR50.55(e) . Since the details of this report provide information relevant to the reporting requirments of 10CFR21 for Unit 2, this correspondence is considered to also discharge any formal responsibility PP&L may have in cmpliance thereto.

We trust the Ca mission will find this report to be satisfactory.

Very truly yours,

/l 'O '

W N. W. Curtis W

V.P. - Engineering & Construction - Nuclear WPG:sd Attachment /\

8310280139 831010 \

PDR ADOCK 05000388 /, 0C S PDR v til

.p . 3 ..

< October 10, 1983 2 SSES PIA-1902 '

+ -

.ER 100508 . FILE 821-10 Dr. Thcznas E. Murley s ,

M f 1-Copy to:

, . Mr. Richard C. DeYoung (15).

Director-Office of Inspection & Enforcenent

,  ; , U.S2 -Nuclear Regulatory.Comnission Washington, D.C. 20555 -

Mr. G. Mcdonald, Director Office of Management Information & Program Control-'

U.S. Nuclear Regulatory cnnission Washington, D.C. 20555

. Mr. Gary Rhoads . .

.U.S. Nuclear Regulatory Camission' P.O. Box 52-

,. Shickshinny, PA 18655-

- Records Center-

' Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, GA 30339.

gi j n. '

. .. c._.-

- Attachment 1 SSES ' PLA-1902 EPagel1 of'3 , ER'100508 FILE 821-10 ,

1 Interim Report-

,  ; SUBJECT-Isolation'of the Unit 2 Nitrogen Makeup System DESCRIPTION-

, It has been determined that the primary containment isolation system

' Division 1II relay (K83) provides a closure signal to_ the drywell nitrogen

supply outboard isolation valve (SV-25767) and the containment atmosphere-

^

' control sample inboard isolation valve-(SV-25776B). . The drywell nitrogen supply'line taps into s the. containment; atmosphere sample line between the rinboard, valve (SV-25776B) and the outboard valve (SV-25774B) (see-attachment) . With the nitrogen makeup; system'in service; coincident with a

~

Lloss of coolant accident, the K83 relay could fail in such'a manner as to.

maintain SV-25776B and SV-25767 open. This configuration could create a 1

direct path;from primary containment to the"outside environment through the

-non-safety related nitrogen makeup system should it fail. A similar scenario Lis applicable to the suppression. chamber nitrogen supply isolation valve

-(SV-25737) and thet containmen( atmosphere control return inboard isolation valveL(SV-25736B).

CAUSE-The deficiency resulted from a previous change of the power supply to the -

inboard isolation valves from Division I to Division II in order to prevent a loss of Division I power from closing the valves and preventing the operation of the Division'II containment atmosphere sample system.-

SAFETY IMPACT The nitrogen makeup system is isolated from the drywell by two 1" energize to open (fail closed) process solenoid valves. The same arrangement exists for the suppression' chamber. During normal-plant operation the makeup system is

! used intermittently..

In order to provide a direct. path to the' environment, the following events must occur:

(1) A LOCA

/

. 2). Failure of the. isolation relay (K83) to change states

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Attachment- SSES PLA-1902

.Page=2 of 3 ~ ER 100508 FILE 821-10

3) Operation of the utcrogen makeup system prior to and during the HLOCA. (Note :-- Operation of the nitrogen makeup system during any condition where the drywell pressure exceeded 1 psig would be a violation of the alarm response procedure and indicative of still another failure of the pressure control interlocks-of the nitrogen makeup system.)

4) A line break or tank rupture in ' the non-Q nitrogen makeup system.

Although the simultaneous occurrence of these events is cors. 'dered to be

-highly unlikely, the possibility does exist. It is, theres z.a . considered to be reportable under the provisions of 10CFR50.55(c).

CORRECTIVE ACTION A permanent design modification is to be implemented under PMR 83-536.

Although different piping schemes are currently being evaluated, each scheme provides for a minimum of 2 redundant isolation valves in each of the nitrogen makeup lines to the containment. One valve will be powered from and isolated by the Division 1 power supply. The second valve will be powered from and isolated by the~ Division II power supply.

5

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Attachment i SSES PLA-1902 Page 3.of.3 ER 100508 File 821-10 Unit 2 Nitrogen Makeup System' Isolation Valves N2 Supply

. . i SV-25767 From

!  ! Sample SV 25776B SV-25774B Drywell SV-25737 l -

Wetwell 1 y, SV-25736B SV-25734B l

_