ML20215L059

Responds to Request for Assurance That Facility Neutron Monitoring Sys Design Similar to Design of Other Plants.List of Plants W/Similar Design,Already Reviewed & Approved by Nrc,Encl

ML20215L059
Person / Time
Site:	Hatch, Peach Bottom, Nine Mile Point, Fermi, Hope Creek, Cooper, Susquehanna, Columbia, Brunswick, Limerick, Vermont Yankee, Duane Arnold, FitzPatrick, LaSalle, 05000000, Shoreham
Issue date:	06/22/1987
From:	Artigas R GENERAL ELECTRIC CO.
To:	Thadani A Office of Nuclear Reactor Regulation
References
GBS-042-087, GBS-42-87, MFN-044-087, MFN-44-87, NUDOCS 8706250532
Download: ML20215L059 (3)

Text

.

ggggggyp 1 PAGE 1 of 3 GENERAL $ ELECTRIC

' f NUC1.EAA ENERGY ENGINEEA NG DM$10N CENEW ELECTRIC COMPN # # 175 CURTNER AWNUE o $AN JOSE, CAuf0RNIA 95125 M/C 682, Ph. (408) 925-5040 GBS-042-087 MfN-044,087 l

June 22, 1987 1

U. 3. Nuclear Regulatory Commission l

Division of Engineering and Systams i

Technology

{

Washington, D. C. 20555 Attentions Ashok C. Thadani Assistant Director for Systems Gentlement

SUBJECT:

SIMILARITY OF NEUTRON HONITORING SYSTEM DESIGN This letter responds to your request for assurance that the Nina Hile Point-2 (NMP2) Neutron Honitoring System design is similar to the design of other plants. NMP 2 is presently under your review and' Niagara Mohawk Power Corporation (hHPC) has submitted or will be submitting additional information with regard to the.Neutr,on Monitoring System design and interfaces.

The Neutron Monitoring System (NMS) design basis and implementation equipment is assentially the same at Nine Mile Pointa2 and the plants listed in Attachment 1.

This design has been reviewed and approved on the individual dockets of these plants.

One of the important documents already reviewed by the NRC was GE Topical Report NEDO-10139,

" Compliance'of Protection Systems to Industry Criteria." (June 1970).

We believe your previous review of NEDO-10139 should respond adequately.

to your specific concern about the isolation capability of the Neutron Monitoring Systam interfaces. However, va are preparing an analysis which substantiates the acceptability of the existing design and equipment for your further consideration.

This analysis will be l

provided to htPC for submittal on the NMP-2 docket within the next few days. This analysis also represents an acceptance basis-for all the other listed plants.

GE believes that the existing NHS design at NMP-2 and the other plants is safe and represents no threat to the health and safety of the public.

+

confirmatory data to further pupport the analysis, if determined to be necessary, can be provided at the conclusien of a test program which could be completed by October 2, 1987 7

p 625 053*gg.

1

~*

PAGE 2 of 3.

-i; i

i USNRC l

(

Page 2

~ June 22, 1987 I hope that the above information adequately responds to your re'uest.

q

Sincycly,

[

fA A

l&

I R. Artigas, Manager, Licensing fi Consulting Services 1

RA/dc cc:

H. R. Paffer R. I. $kavdahl.

j 1

(

c i

f i

e i

~

u

~

L.

n v

1 o

l l

\\

L'

[

d

r.

r PJE 3 of 3 l

ATTACHKENT 1

[

Domestic pihnts with Neutron Monitoring Systam panels essentially the same as:

.Nine Mile Point 2 Match 1,2 '

Vermont Yankaa Peach Bottom 2,3 Cooper Duane Arnold Fitspatrick

' Brunswick 1,2 i

LaSalle 1,2 Shoreham Fermi 2-Hanford 2 Susquehanna 1,2 Limerick 1,2 Hope Creek O

l i

E it 9

5 E

j

' s, I

l

e a..

1

~

ATTACHMENT'2 G E N'E R Al.ME L E CT RIC M/C 38'9 (408)925-3798

' June'22, 1987-Responde~to:

Response Required by:

NA-NMPC-632

)

Mr. R. J. Cohen, Manager Sice Services-s Nine Mile Point - Unit 2 PO Box 63 Lycoming, NY:

13093

.)

ATTENTION:

K. Ward

~4

SUBJECT:

NSSS CONTRACT No. PC-FMP2-1 NMP2 FMEA-ISOLATION DEVICE ANALYSIS j

NINE; MILE POINT NUCLEAR STATION - UNIT 2 NIAGARA MOHAWK POWER CORPORATION Gent 3cment A' t the request.of the NRC, GE was. asked to evaluate the adequacy of-isolation between signals within Neutron Monitoring panels and Non-class

.lE systems.or devices, such as computer and annunciator inputs.

The attached.provides our evaluation.of these circuits.

The design review for Nine Mile Point 2 de essentially the same denisn as used on all other BWR 4-and BWR 5 plants.

Elementary diagrams for the Power Range Neutron Monitoring System, Process Radiation Monitoring l '.

System, and 4 tart-up Range Neutron Monitoring System were reviewed to

. identify. interfaces to external Non-Class 1E~ system and devices.

Each

~ interface was evaluat'ed fsr impact of a short to ground, an open circuit.

and application of.120 volte AC (maximum credible voltage).

GE's analysis of thnee interfaces concludes that the consequences of shorts,-_

opens, and hot shorts will not prevent the system from performing its required gi p safety rdiased functions.

j-;

g The attached provides a description of the circuita in question and our q'

[

cjustification for the adequacy of design.

I i:

)

I j

i i

i i 1_

m I

s 1.

D. Ward June 22, 1987 hHPC-632 Page Two-The FMEA and' Letters on 02 tant program and Generic commitments should allow-the NRC to proceed with the full power license as discussed with NRC and hWPC Honday,- June 22, 1987,

- Very truly:yours.

/

H. R. Pat Project Manager

'Nine Mils Point 2 i

HRP:dd

- cc R. J. Hali R. M. Pulaffer K. Varadarajan W.-R..Yaeger J. R, Robles H. H. Engelking R. Abbott Files i

4 i

l.

\\

f-l I

I

i

~

NMP2 M13-P_6_08 ISOLATION DEVICE ANALYSIS

.)

1.

_ Scope.

This document describes the types of isolation devices used in the Power. Range Neutron Monitoring System Cabinets H13-P606, P608, and P633 to 1

t provide en interface for signals from Class 12 circuitry, to non-Class JE.

circuitry. The function of these devices is analysed with respect to the j

presence of various abnormal signals impressed at the circuit outputs.

m

)

2.

. Required Safety Punction.

The interaction of protection system signals i

with other systema is described in IEEE Std. 279-1971, sect. 4.7.2.-

The i

basic requirement is that "No credible failure at the output of an foo-lation device shall prevent uhe associated protection system channel from

-meeting the minimum performance requirements specified in the design 4

bases."

30 Analysis _ of IgC1stio_n Functions.

3.1 Coil-To-Contact or Contact-To-Contact.

Relays providing 1

coil-to-contact isolation are of the three following types:

4 1

a.

' Potter di Brumfield xH series' b.

OE type 3 SAT j

c.

Potter & 3rumfield MDK5117 Each of.these. relays can withstand 120 VAC across any contact and will not break down to the coil under these conditions.

These relays will 3

5 also withstand up to a minimum 500 V RMS between contact seten thus, contact-to-contact isolation is also supported, shorting across a i

contact or shorting from ofther side of a contact to ground has no effect on the input circuitry.

Opening the output circuit likewise has no functional effect, on the protection circuitry, since there is no voltage to feed back.

3.2 -Fuse /Zener Diode Combination.

In this configuration, a sener diode with a breakdown rating higher than the expected normal signal maximum is connected from the output to ground or signal comtion. A fast blow 30 mA fuse in series with the output protects the output circuitry by opening when a high voltage. transient causes the sener diode to break e

down.

Use of a sener diede instead of the fuse alone greatly increases j

the probability that the fuse will open.

The diodes have sicher a 5.

10. or 15 v rating, so a high external voltage (120 VAC) will cause a ji sharp increase in current through the fuse and sener diode.

Since the current is only limited by the sener impedance, the fuse will monentarily pass up to 50 times its rated current and can be expected to open within 1 mnee.

For other abnormal cases, shorting the output to ground has no effect on protection circuitry since tha output circuit's 0

voltage divider resistors (see item 3.3) will limit current to less i

than the fuse's rated value.

Opening the output circuit also has no i-effect on the protection c.treuitry (no current through fuse).

p 3.3 Current Limiting Resistors. All analog outputs from the Neutron Monitoring System to non-1E systems are derived from higher voltage signals through voltage dividere.

The divider outputs are protected by the -fuse /sener diede combinations se in item 3.2 above. ' However, abnormal high voltages may exist for up to 1 mese before the fusa opene.

In this case, the divider resisters provide current-limiting i

protection to the 1E circuitry.

The voltage dividers are, driven by

{

operational amplifiers as described below, so.their low impedance i

outputs will not be affected by momentary-transiente.

3.4 Buffer knpitfiers. Many analog outputs to non-1E systems are protected by high input impedance, low output impedance operational amplifiers operating at unity gain.

These amplifiers drive voltage dividers and the fuse /sener diode protection circuit described in item 3.2 above.

To an external high voltage transient, the buffer amplifier output appears to be nearly at ground potential; thus, the abnormal voltage will not be seen at the buffer input.

The buffer output will.euttain the increased current until the fuse; opens within 1 meec.

In some circuits, there is no separate buffer amplifier, but the main op amp, with its low impedance output driving the voltage dividers, will also

_ prevent an external voltage from being impressed on the normal signal level.

The voltage divider resistere provide additional current limiting.

The buffer amplifiers (type 741) can sustain a short circuit to ground indefinitely.

An open output circuit, driving no load, does not affect the input circuitry.

4 I

i l'

L

.c i

ATTACHMENT 3 REQUEST FOR EXEMPTION A.

Introduction-4 f to Niagara Mohawk Power Corporation's letter of June 23,.1987'

'(NMP2L 1057), contains a Failure Modes and Effects Analysis ("FMEA")

report evaluating the effect of certain non-Class lE devices connected to Class lE neutron monitor.ing circuits without isolation devices consistent with the NRC Staff's current interpretation of IEEE 279.

Niagara Mohawk has.been~ advised by the NRC Staff of its view that these isolation devices mayunot achieve full compliance with 10 CFR.50.55a(h).

1 In accordance with the provision of 10 CFR'50.12(a), Niagara Mohawk Power Corporation hereby requests an exemption for Nine Mile Point Unit 2 from the requirements set forth in Title 10. Code of Federal Regulation (10 CFR) 50.55a(h) for.the type.of components listed in Attachment 2 and discussed herein.

This attachment demonstrates that the requested exemption presents no undue risk to the public health and safety, and that special circumstances-are present that justify' granting the exemption.

This exemption has been reviewed and found to be authorized by law and consistent with the common defense and security.

3319G

i

~

ATTACHMENT 3 (Continued)

Hith regard to the " common defense and security" standard, the grant of the requested exemption is consistent with the common defense and. security of the United States.

The Commission's Statement of-Considerations in i

support of the exemption rule note with.approva', the explanation of this-standard as set forth in Long Island Lighting Company (Shoreham Nuclear.

Power Station, Unit 1), LBP-84-45, 20 NRC 1343, 1400'(October 29, 1984).

There, the term " common defense and security" refers principally to the z

safeguarding of special nuclear material, the absence of foreign control U

over the applicant, the protection of Restricted Data, and the availability of special nuclear material for defense needs.

The granting of the requested exemption will not affect any of these matters and, thus, such grants are. consistent with the common defense and security.

i j The proposed exemption has been analyzed as discussed below and determined I

not to cause additional construction or operational activities that may 1

significantly affect the environment.

It does not result in a significant increase in any adverse environmental impact oreviously evaluated in the Final Environmental Impact Statement-Operating License Stage, a significant change in effluents or power levels or a matter not previously reviewed by the Raclear Regulatory Commission that may have a significant adverse environmental impact.

i I

i 3319G

pn N

ATTACHMENT 3 (Continued)

-6 n,

y.f, Niagara Mohawk requests an exemption to 10 CFR 50.55a(h) be granted until

)

a permanent resolution satisfactory to the NRC of the isciation device j

wissue is achieved on a generic basis.

Niagara Mohawk commits to 1;1mplementing any NRC mandated modificatictu during the first refueling (t,

f outage after the modifications are made available for installation.

It is-expected that any design changes can be implemented at the first refueling l

1 l

outage.

.c

(~

1 l

B.

Discussion}

x s

Asaresulty'x,recentmeetings,theNRCstaffstateditspreliminary f

t s-j 9o posit' ton that.the current design of the isolation devices in the neutron monitoringsystemmaynotmeetthefullrequirementsof!iEEEN79.

A.

I pK.

Failure Modes and Effects Analysis (FMEA) was performed for 'the Nine Mile s"

,t Point Unit,2 neutron monitoring system to demonstrate that the dailure of l

~

y' the isolatioh devices would nc t nNersely affect the connected Cids lE l

5 q.

circuit, or any other safety function.

The analysis confirmed that each v'

isolation device type analyzed has no credible' failure mode that would h

i l *,

adwrsely affect the connected Class 1E circuit or the safe operation of the, plant.

General Electric has stated that the current Nine Mlle Point l

Unit 2 design is the same as the neutron monitoring system at other BWR plants, including recently licensed plants.

If the submitted FEMA does not resolve all staff issues, confirmatory data to further support the analysis, if determined to be necessary, can be provided at the conclusion of a test program which could bh completed in October 1%7.

1 i

3319G i

e,

-L i.. m.m m.5

i

+

1 n~

-ATTACHMENT 3-(Continued)

-+.

h l

m

+

y ;

f

.i' N

' C.;. Justification-r 'r Implementation Schedule o

r The-currehtLHine Mile Point Unit 12 design is the_same as the'neutroni

(

monitoring systems at other plants supplied by General Electric, including:

.l

.recently licensed plants.'.1 General Electric has supplied a FMEA.foF Nine:

Mile' Point Unit 2 which concludes that the consequences of-failures

. reviewed therein will not prevent the system from performing its: required j

i

- safety functioni Additional specific justification for interim operation-o

- of Nin'e: Mile Point Unit!2 is~as follows:

i p

1. l The. processing electronic equipment associated with the neutron Emonitoring'. system is. located-in the mild' environment of the con. trol--

s

' room;

- 2.

The ' equipment is. located in control, room panels which.have been

.. seismically qualified to the Nine Mile Point Unit l2 seismic licensing-criteria.

3.

Pancis similar'to those at Nine Mile Point Unit 2 have been qualified i

as Class 1E by General Electric.

l 4.

Similar equipment has been in service at other licensed BHRs for

,q approximately 15 years.

f x

-S'-

This system is a fall safe. design in that loss of power to the. system

'will *a ttr protective action.

J l

. hi 3319G If-

\\z

~

ATTACHMENT 3 (Continued)

D.

Conclusion i

Def'erral of any required modifications to.the neutron monitoring ~ system

)

components until the resolution of this issue does not present.an undue 1

risk to the public health and. safety. As stated in the attached FMEA report the failure of the present neutron monitoring system isolation components has no adverse effect on any other safety function.

The i

neutron monitoring system is a de-energized to operate system which will fail safe.

The current design is the same for neutron monitoring systems l

at other BWR plants, including recently licensed plants.

E.

Special Circumstances Are Present I

l Special circumstances are present which warrant issuance of this requested exemption.

These special circumstances are discussed in accordance with the classification contained in 10 CFR 50.12(a)(2):

(iii)

Compliance would result in undue hardship or other costs that i

are significantly in excess of those contemplated when the regulation was adopted, or that are significantly in excess of those incurred by others similarly situated.

Compliance with 10CFR50.55a(h) would result in undue hardships that are significantly in excess of those incurred by others similarly situated.

The current design meets the same standards for conformance with the regulatory requirements for the General Electric neutron monitoring safety 3319G i

i v

[

. ATTACHMENT 3'(Continued)

system at other BWR plants, including recently licensed plants.

., Compliance _a'tthepresentjtimewouldresult.insignificantfinancial hardship to. Niagara: Mohawk Power Corporation.since theLlowl power testing

of Nine~ Mile Point Unit 2 of up.to 51. of rated. power will be' completed by.

late June 1987, and Niagara Mohawk will be awaiting the full powerL11 cense.

~

Eat that time. Any delay in issuing the full' power license will.directly Limpact the commercia1' operation of Nine Mile Point ~ Unit 2.

.(v).The exemption would provide only. temporary relief from.-the applicable regulati_on and the. licensee or applicant has made good faith efforts-to c'omply with the regulation.

This exemption request would provide Nine Mile Point Unit 2 with only temporary relief from' compliance.with the requirement of 10CFR50:55a(h).

Niagara' Mohawk hasimade good faith efforts to comply with'the regulation as soon'as-informed of the Staff's position in this matter. The subject isolation' devices were only.recently identified by Niagara Mohawk as not i

conforming to the~NRC Staff's interpretation of IEEE 279. A Failure Modes

.and Effects Analysis is being submitted to the Nuclear Regulatory Commission as Attachment 2 to this letter.

The Nine Mile Point Unit 2-design'is similar to the design of other recently licensed BWRs and-l

.. Niagara Mohawk could not have reasonably anticipated the need for possible further design and component upgrade.

Thus,:special-circumstances exist warranting the grant of the exemption.

3319G c

j t

' ATTACHMENT 3 (Continued)

F.

Environmental Impact The exemption' request would allow operation of the plant for a specified time to resolve the NRC Staff's questions regarding the adequacy of the specific isolation devices in the neutron monitoring system.

The proposed exemption has been analyzed and determined not to cause additional construction or operational activities which may signit'icantly affect the' environment.

It does not result in a significant increase in any adverse environmental impact previously evaluated in the Final Environmental Impact Statement-Operating License Stage, a significant' change in effluents or power levels, or a matter not previously reviewed by the Nuclear Regulatory Commission which may have a significant adverse environmental impact.

The proposed exemption does not alter the. land use for the plant, any water uses or impacts on water quality, air or ambient air quality.

The proposed action does not affect the ecology of the site and vicinity and' does not affect.the noise emitted by station.

Therefore, the proposed exemption does not affect the analysis of environmental impacts described in the environmental report.

3319G t