ML20138N668

Single Failure Analysis for Neutron Monitoring & Process Radiation Monitoring Sys

ML20138N668
Person / Time
Site:	Hope Creek
Issue date:	10/15/1985
From:	Public Service Enterprise Group
To:
Shared Package
ML20138N654	List: ML20138N652 ML20138N668
References
RTR-REGGD-01.075, RTR-REGGD-1.075 NUDOCS 8511050286
Download: ML20138N668 (11)

Text

s SINGLE-FAILURE ANALYSIS FOR THE NEUTRON MONITORING AND PROCESS RADIATION MONITOR!dG SYSTEMS HOPE CREEK GENERATING STATION s PUBLIC SERVICE ELECTRIC AND GAS COMPANY OCTOBER 15, 1985 4

P f 8511050286 831030 PDR ADOCK 05000354 E PDR

_1-b 1

SIl1GLE-FAILURE AtlALYSIS FOR THE NEUTRON 140NITORING AND PROCESS RADIATION MONITORIt'G SYSTEMS Some of the safety related portions of the neutron monitoring system (NMS) and the process radiation monitoring system (PPJ!S) for the Hope Creek Generating Station (HCGS) are not designed and built to conform to the literal separation guidelines of Regulatory Guide 1.75. .This analysis establishes the acceptabil ,

ity of these portions of the HMS and PRMS by demonstrating that they meet the single-failure criteria of IEEE Standard 279, which requires that tne conse-quences of any single, design-basis failure event in a safety-related portion of the systems be' tolerated without the loss of any safety function.

Portions of NMS and PPJiS External to the NMS and PRMS Panels See Figure 7.1-1 of the HCGS FSAR for the separations concept of the reactor protection cystem (RPS) and its relationship to the NMS.

Under the reactor vessel, cables from the individual, local power range monitor (LPRM) detectors and from the individual intermediate range monitor (IRM) detectors are grouped to correspond with the RPS trip channel designations.

These cable groupings are run in conduit from the vessel pedestal area to the HMS and PRMS panels.

- The radiation monitors on the main-steam lines are physically separated. The cabling from the individual sensors to the panels is run in separate metallic conduit.

Cabling from the NMS and PRMS panels to the RPS cabinets is also run in metal-lic conduit, providing electrical isolation and physical separation of the HMS and PRMS cabling associated with the RPS system.

It 'is concluded that the safety related portions of the NHS and PRMS external to the NMS and PRMS panels adequately confom to the separation criteria of Regulatory Guide 1.75.

t

' Sinole Failure in the NMS and PRMS Panels Figures 1 and 2 depict schematically the physical arrangement of the equipment in NM5 and PRMS panels H11-P608, Hll-P635, and H11-P636. The designs of these panels are similar to those of NMS and PRMS panels used in several BWR plants accepted by the NP,C.

The layouts of the panels and the assignments of specific RPS trip logic circuitry provides the designs with the required tolerance to postulated single failures. The worst-case single failure would be the loss of any combination of trip signals within one bay of any panel. However, the loss of any bay and its associated wiring would not prevent a scram. A valid scram signal would be transmitted via the other bays because of the redundancy in the panel designs and the interconnections to the RPS (see Figure 7.1-1 of the HCGS FSAR).

The eight IRM channels and the six average power range monitor (APRM) channels are electrically isolated and physically separated. Within the IRM and APRM modules, analog outputs are derived for use with control room meters, record-ers, and the process computer. Electrical isolation at the interfaces would prevent any single failure from influencing tt trip unit output.

Physical Separation in the NMS and PRMS Panels Adequate separation, in the HMS and PRMS panels is achieved by using the bay design depicted in Figures 1 and 2, by using relay coil-to-contact as suffi-7 cient separation / isolation, and by separation between divisions / channels / wiring.

! Where conformation with Regulatory Guide 1.75 separation criteria cannot be' achieved, the best-effort design is used.

1 Circuits that provide inputs to different divisions of the RPS are physically separated by airgaps or by the walls between the bays. Within the panels, where the cable and wiring runs to the different RPS divisions do not conform to the Regulatory Guide 1.75 separation criteria, fire-resistant "Sil-Temp" tape is wrapped around the cables and wires. This eliminates the possibility of fa' ult propagation between the RPS divisions. In accordance with paragraph 5.6.2 of IEEE Standard 384, this tape has been demonstrated to be acceptable.

' Hon-RPS interfacing cables or wires not conforming to the separation criteria of Regulatory Guide 1.75 were not wrapped in SIL-Temperature tape.

e

l Separated ducts are provided in the panel for the incoming circuit wires from the sensors that belong to UPS Bus 1 or Bus 2.

As shown in Figure 3, the isolation / separation precludes the propagation from outside the NMS cabinets of failures that could cause the loss of any safety function.

N!4S/FR!45 Interface to RPS 1

l Although the LPPJ4 sensors are not required to meet Class 1E requirements, the design bases of. the APPJ4s specify that the LPR!4 signals used for the APR!4s be so selected, powered, and routed that the APRMs do meet applicable safety criteria. The LPRM signal conditioners and associated power supplies are isolated and separated into groups.

Tne logic circuitry for the NMS and PRHS scram trip signals conforms to the single-failure criteria. The contact configurations and failure consequences associated with IRl4 A (see Figure 4) and APRl4 A (see Figure 5) are typical of the other trip channels and are described in what follows.

~

• With the reactor scram mode switch in the " Shutdown," " Refuel," or "Startup" positions, IRM A upscale or it.eperating signals (unless bypassed) or APRM A upscale or inoperative signals (unless bypassed) would prcduce a channel trip of the output relay.

• With the reactor system mode switch in the "Run" position, IRM A upscale or inoperative signals (unless bypassed) and an APRM A downstale signal (unless bypassed) or APRM A upscale nertron trip or upscale thermal trip or inoperative signals (unless bypassed) would produce a channel trip of the cutput relay.

• A trip of the channel output relay for IRM A and APRM A or a trip of the channel output relay for IRM E and APRM E would produce an RPS Al channel trip. In PRMS, the log radiation conitor A would produce an RPS Al l channel. trip (see Figure 6)..

l 1

! For HMS, one tripped (unbypassed) channel on the RPS trip system would cause a half scram. If one APRM bay were to fail in an entripped condition, the l remaining bays would be capable of sending RPS sufficient scram signals to I

produce a full scram, even if one of them were bypassed.

As shown in Figures 2 and 7, if one bay of panels H11-P635 or H11-F636 were to fail in an untripped condition, the remaining bays would be capable of sending sufficient RPS signals even if one of the IRM channels were bypassed. The IRM bypass switches can bypass one IRM channel at a time.

Similarly for PRMS, if one bay were to fail in an untripped condition, the remaining bays would be capable of sending sufficient RPS trip signals to produce a full scram.

Common Power Supply Justification The HMS is supplied with 120-Vac, 60-Hz power from UPS busses 1 & 2. A design change has bien authorized for the installation en each bus of redundant

-clectrical protection assemblies (EPA's), which will monitor the incoming voltage and frequency.

Any fault in one HMS channel could not cause an unsafe failure in another channel sharing the same low voltage power supply because 10-amp fuses are installed for wire protection, and the power supplies are designr.d 'uith over-voltage and over-current protection circuitry at their output. -

The PRMS is supplied with 120-Vac, 60-Hz power from RPS busses A and B. EPAs are already installed on each bus to provide voltage and frequency protection.

Any fault in one PPJiS channel could not cause an unsafe failure in another channel sharing the same power supply because 5-acp fuses are installed for wire protection, and the power supplies are designed with over-voltage and over-current protection circuitry at their output.

L

.Because of the fail-safe NMS/PRMS logic configuration, a loss of one supply would result in a half scram signal to RPS. Loss of both supplies would result in a full scram.

Common Associated Circuit Interfaces Nonessential (' associated)' circuits to common information equipment are current limited and protected such that their failure cannot jeopardize an adjacent circuit.

. Figure 8 provides an example of an associated circuit interface on LPRM card Z11. At-the zerv-to-160-mV computer output, the card is protected with a 30-MA fuse. The zero-to-10-V output to the rod block monitor has an additional isolator protection for the card.

J 6

W I

l

t RPS RPS APS -

(M) (A2) (AI) (A1) o 6 o o APRM CH. A APRM CH. C APRM CH.E PANEL (l/PS BUSi) (UPs BUS i) (UPSSUS1)

HH-P606 ~~~~~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~ ~ ~ ' ' ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

BAYi BAY 1 BAY 3 BAY 4 BAY 5 APRM CH. F APRM CH.b APRM CH.S (ursaus1) (t>Ps aus 1) (UPS BUS 2) ~

v v v u (BI) (B1) (B2) (BI)

RPS RPS RPS

. FIGURE 1 - APRM Panel Assignment ,

. I f' t-RPS (B2) RPS(AL)

, a a. .-

ppS(y) ppS(Aj) 4 s I

L04. RAD. McW LOS. AAb. NOM I L%. RAD. MOM LOG.7AD M0W.

\ 2MVDC BUSB 224VCCBUSh

^ EANEL PA^!E L Hit-P635

• 224VDC susa tMVDC BUS A  ;

HII-PG3G IRM IRM ~

IRM cH. D CH.H

.IRM CH.C CH. 4 ca.s ca.f cn. A cH.E U..U 1- .s .

1' .i '

' r R P.$ RPS '1 1 1 r

~RPS PPS 1

(B2) (B2) RPS RPS RPS RPA (A1) (AL) .

(gy) (gy) (A)) [Aj)

.2 . .  ; ..

' FIGURE 2 - Radiation Monitoring Panels .. ,

~

• j$ ' ,b: *

• • [ ~ ';'

. . . . _ . . n. .u. a . n. .  ;: ,

,. I y', )' '

y . ; . g, f ; q c.n.

, . w Qy..'g-y ey &E v %? P' : Yi'?', " ,  :

" , ,g,;i; '

, 'c , x;v. 2. . .

g-;.

q ,y, -y,j;s ~. =- ~~ it r iM!O ,-h 2 d~'a *'

~

i, f y ' > '=; ,.

- ?

th. h ' yL.* , .

h5 ' ' ,

W ?

• Q . j_G ~ l . -: -

- - ~ - - ~ ~ - ' ~~'

~~

r 4

PENETRATIONS APRM Quay yp,p (p,y l -------_~~~~~~~~~~I, Hil-P606 i \

dl

, l ,

D I ovaco f APRM ly piy,1 l

CH. F ' qMi i dj I l Is AM CH. D a B

__ cw200 _

l

> Div. /

c FROM Lppu <

l l

^* ##* 0 - e

 % [ ,

I l ~6ENSCRS

• l t

I ,s i

B w.,

l A PR M en. S 's A &

l ' - '

H: ,4 1 I -'

Aw200 APRM C n

• i i s . -1 C#. E "

E ' > b'Y A l ,

% l l d! I L

---

___-._________Is FIGURE 3 - APRM/RPS Signal Sroaration .,

1 l

l

, s. , .

k- . *,

'*],jl5 ~'

d -l.' .D: ;-: Ii' ' ; ' : ' ' U" ' (

'O

~ : . . <~ 4Q:;,. '

• QE

4. .. .. _

'{ ' }

.c l

< {g . '

', .I ' - h. *A _ , i, . . ', .  : i

-.e

+ . ..  :, .,.,. . ._-: -,.

.. g .

. . y . e, - ~

. . ,a- .-

y L .. . .

,:.a. .

....-- - ~ . . . --.-...I

. ,e , . .

T

)

tm IR98 CHAN A J7 -5 55 e r - + --

8

..K30 I s a"" (INOP)

--K41 5' DY- 0 K33 I NW ::wPset. 8 4 TRi?)

54 18!'wx. vella --

A- -

4

' FIGURE 4 - IRM Channel A 0

. t ~ t tx on

_. __ PANf.b -

AptM GeANNEL A

• Ph08

' J% , des J41 TB SI g, q <>

7 c._ r

< .s 51

/

ss - l :: co

- . onse. s, eve .

l 1 O A:

e

.j v:

i .

i

=2 , --'

6 iwo -

I.

. i ::co a w

- 'Tuase TRtPuw. 6 r

'_f_

o.. we unec w n.

TRIP .

i A

' $ =

.'i ..

. " p*

. m.

~- >

+ , @ - - - _ - . = . . I e, ', . .

-m:j .- " 's '

i . 'FICURE 5 - APRM Channel A L ,. . . .

w.; ,

4,r

1. ' r v . {,fe -- ..

'-c. re -.s.** * . ' - * . 3 r,

'... ' * * , *M~

j~ + }k' ~ ' y '

~. *Th ~ g{$.a *!sh '?h.Q }.i- ' < '! '

.,M + ;-y

.a. . .  ; b., . , , , , s s , j ag;dt y,-

,,', ,.-... ,'.+ . p.e.w

. pt . . ' ,. , , . .

,,,i..

s. __ , .

+t ., .j;,, . , ,

i w,....- ...5.,

6 3.  ;# ., . ..

~ ' ' '

.fGjh.5 N ; %$ (y .A."YllO-

• * ~ ' ~ * -

,, s. qa : s: >-- '

%N,[* vs..g'*L .< r:

Q 6

4 e 4 .t' .

s c Us .;f. a, s ".:~  %

. osr

.. e

++  : t .. a = . a. . o. . , r4

• , =

y 3'e., . .

s l *, *);* g , r *> . :a ~ ,

,' [

g

..r.

ef~,

,y:

i <,.N.

~ , .p~. ..h- ,.

y. n.' .. > , ,

' I k, .I 9"' ,g ,

=s , s .., N,

~p ':S *. n > ~ ;'

s- f~. '.4, ,

. - 's

- . . . , ,s . .

w r r:r e- ~. ! bi..- ' ..

~. .* b;% , , .

. y .%p.gf .M. 'dj, 'i .

~..

a <

, e, . - - .

r. ; C .

. ,o ,%ue,

.h -

cc-e .' CRM AE USS T5di, 'I^

..]..-

• e

,c k - ,

'

• jry 24 '

'e  ; . 9C18 $ .13dbd >. - t .

A f,;. 9

+s~. g.' . h' ,.

4. ,;h 'y'.. .j , pg ,10 Anas.

CXT (maa

't* j < g . ~

sc7e.h Terrie 364.1 3 -

3 eMH(HH*d t gg b

t .

' to ~u*

'.~ 1(10 Tt37b

+ ,N, ',i l(70M T57-5 MAIM STEAM UkJE RADI" ATIOM

'E ',ff'+

f,

. m s-h b >HIG84 A

pcy3.L. "

g l -

m-97.

k[kf

o -

s .,c

i. - (,' . .

CC-9 i

.h..-.t ;'%' -

T54,-(* MAlu 6 u E 3CTI h CC-6 _ Hg RApagm g

^ #.5  :,'** .

CFDR A.E.uSE)

" ,g . g. TE'S

.:', y ,- ,Q. ,

V , hl U - Ce.e _

{ .

5 '*" *'- .

CC-19. n ,

.s' 7' - pip -', N -

y ji

• 4 p:-

sc73  ;; Tareg

> 04 Ate As

,

• Tgh6 ' Tytwo Auct.wEfA utmy L

$ 1 w m (.54 % Occ.4) t! cssA sc73 T T 8" cc.e , { {I M isa 9tTM SUPPL OCC7)

~

, L pgp

-g-).a  : . :. . .ii..-_, .

hl!.-'{ . . _ . _ _ . . . . , _ . . _ _ _ .. _ . .

FIGURE 6 - Leg Radiation Monitor Channel A Aa

.y  ?

4

/

S

.' 'e r' 'd a'

,,w =,

. . -. t .m. -' -_ _ _ _ _ _ _ _ _

... ..s .

1 l

e 1-PA m 224VDC POWER SUPPLY 5y3 , Hl/-PG35 '

GMMSWlY RPS BUS A 214VDC POWER 2PPLY _ PANEL _ gygmgry EUS O Hil-PG3G ppS syS 3

+

FIGURE 7 - Radiation Monitoring Panels Power Sources

.' t gg m e eee r i-

~~

, l S8 y

hl l l I 9.3K I

, sans ausrf tiq>al -"

e " I I I

- N AUTO filP-GI --

u 8 " f 7 . -

25g N Tap.at - - ry I ! l 20t . .

' ,,;n.

e .l ; g

- - , - ___ . s' g) a

- y Jn < . M g 'up-an tiep as -

r 3

'Id I 1 43! p Y *'" ((dh oc wr 3 . slas n,

,, 4 k to e c 9a 4g- .

,' J!r <.--ow Q* . A(esef vegg)

' ~

l ,

, J W

l c'" ** a III

--' Sel i

%e 3s8 M '

oevi.

~*'

d I YA.

'sEs c'8 , , , .

a - -,oto .

so co ~ ,a

, f74 ,,* l (% e 44) r .

- '5' (c'8 -

.. a,

@,,) - ,, /A e w . ,

l w ..

f.

FIGURE 8 - LPRM Circuit Card 4R e

5 $ ;*

• 4

, s s

___? ~~ ~ ~

v-

[ ~ ::s - _ ,* j l *,[~r " .- s _

s. - - ; - r

,,e,, g '{

• I '%' ' s 4 ,

y,cc,g.-at d.,r :rr = , .,

't . , . ,

. qi

~j *

. e ; i -) V l i-

~. -

I ,[ e-- g a_

_8'