_ .. __ _ _ _ - - _ - _.

. ,

,

, .

~

. .

u c6ma- yvav -e en

A toweO O.s esO. 3iW-elm'"''" " **'"*

UCENSEE EVENT REPORT (LER)

- <=,m.Aciury =Ame ni

Fort St. Vrain, Unit No. 1 o is ; o g o I o i 21617 1|oF|017m6s

During SR 5.1.2c-X, Only h Of Total RSD Material Was Discharged From CRD#21av =r oAre m te . . re nm amen. mmes naven =

Hg WA6 '

IM DAY YeAA .AObfTv esAm 00cKeT mINN DAY veAA YEAR g g ..

N/A essioisio, , i

1|1 0| 5 84 8|4 0|1|2 0|0 1| ? 0|C A|a oI Gf8fotot i f- ~

v=. --r = n -, to == .nsuiname== = o,= p:n . nn,,e,Ar,,,e' " * * * ' N masw mene. sess nsim

___

m .ss wiw= _=e==m. n. _

_

01010 sseenwmen samme msswam.m_ ,em,,o, y ym ,n

<=> __

menwmem sesswam so a me., -

| ^ ;y ,7 _ _ _

< ~ . m.emme .,

;~ +; _~ - _, __

useuse es vAct =. 6e. neveLie Ga.6 seuessen

esaase- AmeA coo

Jim Eggebroten, Technical Services Engineerino Supervisor 31013 7: 81 51 -12 12 1214-eve c.= A os eAnuna ===nomearos

"*",u',',S ag",'g8 '' ,''j;'I. s-j"'"Q* "T.".L'E*l :$/?, cause sysvam - -rc^use 'vs * co'*oaeat ,, , .

,

"$FN @NE hi i i i i ii i i i iiJM. ,@;;i; igg.us

| | | | t I ; w '' e, ; ; g ; ; ; gaschTu DAY YeAAsuppLeasenrAL se, ORT espsCree fle

'

~l =o 0 13 015 8I5 |7 7] v u m , - a weereo r - aAm

Amer =Act<u . ,.a w . _ . ._ . A, nei ;

l.

I|

!

i

At 0830 hours on November 5,1984, with the reactor shutdown for control rod drive(CRD) inspection and maintenance, the reserve shutdown hopper of control rod driveand orifice assembly (CRDOA) #21 was functionally tested in the hot servicefacility per SR 5.1.2c-X, " Reserve Shutdown Assembly Functional Test". Duringperformance of the test, it was discovered that about 40 pounds of reserveshutdown material (40 weight percent boron) had been discharged from the hopperassembly. The reserve shutdown hopper is designed to release approximately80 pounds of material containing neutron absorbing boron carbide into the coreupon rupture of the hopper rupture disc.

The event was reported to the Nuclear Regulatory Commission at 1225 hours onNovember 5, 1984, per the requirements of 10 CFR 50.72(b)(2) "four hour report".

The failure of the CRDOA #21 hopper assembly to discharge an acceptable amount ofreserve shutdown material during performance of SR 5.1.2c-X is being reportedpursuant to the requirements of 10 CFR 50.73(a)(2)(v).

The reactor remained in a cold shutdown condition throughout this event.

An investigation is presently underway to determine why some of the reserve,

shutdown material was retained inside the CRDOA #21 hopper assembly.'

|8412260031 841205sace==3a PDR ADOCK 05000267'"" S PDR

.- -_ -- _. -! -

_ _ _ . - _

* *.

,

*-. ... . .

o.

r

, , , , , , , . us. nuetsaa aneuuroav -* * * ' LICENSEE EVENT REPORT (LER) TEXT CONTINUATION maovio o=s no. w em

awines; smas

; ,a ur, n, rm ua . mes aFort St. Vrain, Unit No. 1 age w ||7,:||=.... e

'

0|0 012 OF 0 17o |s lo Io |o | 216| 7 814 - 0|112 -

mr - . = ea a wm'

EVENT DESCRIPTION: - ' ,

The purpose of the reserve shutdown system is to provide a means of admittingsufficient negative reactivity into the core to ensure an adequate core shutdown

- ---margin -from any reactor operating condition completely independent of the controlrod system.

'NThe reserve shutdown system is composed of a storage hopper located between thecontrol rod drive mechanism and the thermal shield at the lower end of each~refueling penetration. Each hopper contains nominally spherical neutron absorbermaterial composed of boron and graphite. This absorber material is held insidethe~ hopper by a rupture disc.

A steel guide tube extends from the underside of the hopper to the top controlreflector block of.the associated core region. The guide tube engages the topreflector block, forming a clear passageway for the. reserve shutdown material tofall from the hopper, through the guide tube, and into the core (see Figures 1 and '

2).! Rupture of the hopper rupture disc and subsequent release of the absorber material

into the core is initiated by pressurizing the hopper with helium. Each hopper isconnected to a separate high pressure helium bottle (2200 psi nominal) by apressurizing line that allows helium flow from the bottle into the hopperimmediately above the rupture disc (Figure 3). These bottles have an alarm systemassociated with them that will actuate when the bottle pressure drops belowapproximately 1640 psig, at which time the bottles are replaced. Section 3.8.3.2of the FSAR analyzes reserve shutdown system performance with a minimum heliumbottle pressure of 1500 psig. In this case, if the rupture discs fail to burst at

'

the design differential pressure of 165 50 psi, the hopper pressure could buildto a maximum of 1015 psia. Since the reactor pressure is 700 psia, a minimumdifferential pressure of 315 psi can be imposed across the disc, assuring itsrupture.

~

SR 5.1.2c is performed to determine the reliability of the differential burstpressure of the disc., and detect any tendancy of the poison material to bridge or

| deteriorate in the hoppers over extended periods of time. The surveillanceconsists of placing the CRDOA inside the hot service facility over a pre-weighedcontainer, so that the reserve shutdown material will fall into the container whenthe rupture disc bursts. A helium line and pressure guage are connected to theCRDOA hopper assembly, and the hopper is pressurized until the rupture discbursts. The container is then weighed to determine the amount of reserve shutdownmaterial released during the test.* Eighty teight pounds 'of reserve shutdownmaterial must be released in order to satisfy SR 5.1.2c-X acceptance criteria.

Upon discovering that only forty pounds of reserve shutdown material had beenreleased during the test, maintenance personnel performed a visual inspection ofthe hopper internals using a borescope. The material that failed to. dischargefrom the hopper was removed, and samples were collected for internal analysis.~

Samples were also sent to Los Alamos National Laboratories for Nuclear Regulatory' Commission independent analysis,

g a ==1I - . . _ - - _ .,. . - . . . - , . . . - . . - - ._- -. ,, --. . . - _-

.- .. _- --

* *- . - - . - - . . . . _ . . . - - .

--- --- . .

.,..

... _ . . . - -- -

. o

WA esWCLSAR ReGWLATOR, _esmC h MBA -

UCENSEE EVENT REPORT (LER) TEXT CO'NTINUATION as,aaven ome =a sies e.***'

ameines: emas

ur, n. =e1 ===sa = os. W,.e. . .

Fort St. Vrain, Unit No. 1 .... s=egip ! =| . .

010 013 8' O 170111 2' o p f o lo lo l21617 814 --

v er -. wmi

ANALYSIS: .

The reserve shutdown system is designed to provide sufficient negai.ive reactivitycontrol to achieve hot shutdown conditions from any operating condition without

i movement of the control rods. This condition can be met with two of the thirty-seven reserve shutdown hoppers inoperable per LCO 4.1.6, providing for a totalnegative reactivity insertion of at least .088AK in'the equilibrium core. ,

The capability of pressurizing the reserve shutdown hoppers is demonstrated once-each quarter, during normal plant operation. The " low bottle pressure" alarmcircuitry is functionally tested once per quarter, and calibrated annually toinsGre that any loss of the minimum required rupture gas pressure is readilydetected (see SR 5.1.2). -

An of f-line functional test of a reserve shutdown assembly has been performedfollowing each of the three refueling cycles to date, as required per the Fort St.Vrain Technical Specifications. During each of these tests, the rupture discburst pressure was below 300 psid as required per Section 3.8.3.5 of the FSAR, andacceptable amounts of absorber material were released from the hoppers.

_

~

FSAR Section 3.8.3.4 analyzes the reserve shutdown neutron absorber material andconcludes that bridging and deterioration are not anticipated under thetemperature, radiation, and helium environment in which the material is storedinside the hoppers during operation.

Two reserve shutdown hoppers have been functionally tested as a result of controlrod drive problems recently encountered (see LER #84-008). The two reserveshutdown hoppers tested were on CRD0A #26 and CRDOA #21. During testing ofCRDOA #26, all of the reserve shutdown material (20 weight percent boron) wasreleased from the hopper as designed, however, the hopper assembly of CRD0A #21' (40 weight percent boron material) did not function properly as outlined in thisreport.

|The potential safety consequences of this event are currently being investigated'

and will be analyzed further once the cause and extent of the problem are known.

\

.

.

.

e

6

a

- ,_ . ~ _ . . _ . . . _ . . _ . . _ . . _ . . . _ . _ - . ._ - -

___ .- - _ _._ .-

,- . _ _ .. . . _ . _ .

,

.'.

.

assic pere 1|i A U.S. 88UCLEAR RESULATORY -T~

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Aaraovso ous e o. mo-oiosex, aas: em s.

FaceLITY esaast ste DOCRET seu.mER 421 LER esussegn tel PAGE (31

** =p.a' ! - ==vi.- :

'

ol 0 0 14 OF 0 17oislololo121617 814 - 01112 -

Ten - -. M C wim

_

m. _ .

Onn/\ o

;_.h '-'

-'''-~;"" CONTROL ROD DRIVEj - =,

-5 RESERVE SHUTDOWNi : :: :: -

/ ! .- ASSEMBLY;

l | w oon' -

,

3- - . - Pc.cTaAimas.

-

_

|

.-.-- Pcw

(|runsscatese !' -M , ,'

; ,g = -

w""u'."ve'5 :SYSTEM WELL

Toa acn rcica -. ,, . 79,f,; - - "

% *THtneaAL ,,,,,,,,, -- -gw.pj

-

, % Top my REFLECTot8A"8'E" N I

| | j | n,,|

- . ELrMLat!5!

. -sec nortrcton-

cournot noo -

hacrLtcToR --- ,, ,, ,,,,,, ""',,,gg ,ggy

-*-

soTToMg, ,

,, ,,

c w SUPPORT '''i^' M; #' .

''~ /

.

SLDcMS 'Lr ' 1-

. J | - Cent sampELcore SLs' PORTPOST 5 - e,,

support noon-'d d ' 'rtg j

4-/~co.c s Pro.r- e -.

% ,,,- -/-j -* # - ,,,,,,,sELastw ..

[1 , .

d' O|L#

,;,,,,CWKRA.AfofE MB'

- -Pcw LPeta ~"""'

- -

y -- Lowet naca>

) q.',-rLexetz Couase,

s... .. < -

?- |

N /|, \ geriensDEAD

..

''"*""""*

f~l.cf "

i,,,,,,,'''' , ,,1 .A -

,' } -I t <|| ,

j. _

_. -

Figure. 1. Reacter ; .*

._ ,

. - - - - ~ - --- . . . . . . - .

1; .-

, ._

_. _ _. _ . . . _ _ . _ ., _~__x____.____._._______________._ . _ _ _ . . _ _ . _ _ _ . _ _ __ ._ ,_

_. .. _ ._ ._

,- ,. . _ _ ~ . . .

. .

e

udtCPom me4 U.S. seuCLEAR REGULATOmv _"

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION AaeaovEc oaas sio. 3 iso-oio.EXPIRES. 0/3146

, ACILITY esaast 116 DOCKET sfundBER 12) Len esuess4R to: PAG 4 tal

aIvtam ; sa a, ia6 .

Ip

'

01 0 0|5 0F 0 |701112o15lololo|2|617 SI 4 --

Tuf n- . Rac = m mm

C S

'MOUffrING)FLANGE

j *'

iLEAD SHIELD Y,

. _

.

MECHANISM;_ _ . .

BOR0NATED r

GRAPHITE -SHIELD..

~ '

'

j

R5S5VI~

SYSTEM HOPPER fi.'q. -

/p GdNYd'-~

SHUTDOWN '

GRAPHITE,

i SHIELD i'

b

F|.-) -$

'

9 1 KA0 WOOL

- RUPTURE...

L $ || | [ THERMAL.

'.. SHIELD-. | ,

' -

DISC HOLDER')

, RESERVE [ y $EAL~

'

U E T BE l,

! f. 4 .-'

. ,,

'

i p'OlilFICE VAT.VE' .;| '

,1 ) * LIFTING R0D.

.. |- y ; -

!

h.l ORIFfCEVAlfE''

i /

h!h'

o

SH0CK'

CONTROL RODS N ABSORBER

FIG. 2 CONTROL AND ORIFICING ASSEMBLY

g,,- a

- _ - . _ - - . .= = .=.:_=. = -- :_.

,. .. , . - _ _ _ . . . _ _ _ . . . -. - _ _ . _

_-_ - - - - -

.. -. _ _ . _ .- __ .- .--

-.

, ,*

..

.

eenc posen 3334 ' U1 seUCLEAS LEIULATORY -- - -

"'LICENSEE EVENT REPORT (LER) TEXT CONTINUATION areaovio o.e w. aino-oios

Exetmts e/3145

PACitaTY854888 (16 DOCKET feutSER 82) gga ma qq pagg (3

"m''' - '*J.||,i:viaa

'

I o is lo |o lo | 21617 814 - 01112 01 0 016 0F 0 17-

Tat n- .- a.c = an.wim i

B TO C 15 TYPICAL FOR TOTAL OF 7 LINES*

,

e

8 TO C l$ TYPICAL FOR TOTAL OF 30 LINESC C

1 '7 TQ[4;. " {.i$.)

"_1

i d'#NA.Of& :.jir.{* Tpyi"

1! .

y; RESERVE -' .

*:.i5HUTDOWN -,

: SYSTEM Wj ,

]HORPER < ''""

i!.AND 3;s'

UIDF, NN - -s .

*

*UBE i

*

'' o sr u o_ _

1'k ERIMARY COOLANT SYST'EMMh M | 't!

HS [ M[ i,

'

- t_ _

CORE !!

k

(S) (S)i

| HELIUM HELIUM i 4'

STORAGE STORAGE ,4 ),

CYLINDERS CYLINDERSC M C ;T

' .

e

b i*

...-..

yh. . ..----

4 3r 3 r' db JL

!

(s) (8) ,

C ".

s ...

. ? '5.'|8 E ;-

';i . n. a:.

5, r'*:

._e - Y ,. . *

---

2 v~ ~

. .

m .

HELIUM $TORAGESYSTEM

Fig. 3e Reserve shutdown system flow diagram.

.,

-- - _ - _ - .-.--__:___- : :=- = := = = = = = = = .- .. ...- _ _. -

. . _ . . - _ . _ _ _ - _ _ _ _ _ _ _ _

. . _

g .* . *

.~

--

us. auctaan aammatoav -, , , , , ,

'**" UCENSEE EVENT REPORT ILER) TEXT CONTINUATION waovso case ** sies-****. EMPsata:8/3148

PaceLsTV enmass g,3 00Casi usumsssa es ten sammen im PAGE IS

Fort St. Vrain, Unit No. 1 =mpp ; =.... >

'

010 017 O O [I01112o |s lo lo lo l 21617 81 4 --

min . - .as ance an.wim

' CORRECTIVE ACTION: .

As mentioned previously, the cause and extent of this anomaly are presently underinvestigation, alon.g with the development of an appropriate plan for correctiveaction prior to returning the plant to operation.

A supplemental report will be submitted March 5, 1985..

. .

1 -

_i &_2

\ Jim HillTd :hical Services Technician;

_

; -

/'

[N hM| V NMd Eggebroten

Technical Services Engineering Supervisor

Licensing Review By:,

|

l

Es.1- raJim Graml

Nuclear Licensing-Opera ns. Supervisor.

.

C. H. FullerStation Manager '

'

' J.'W. Gahm/ Manager, Nuclear Production

'

gm-

-_- - - - - - =: :: _ . --z; .==_: - - ----____ r =_____ _: :__-__:. ._- x_

.

1.

public Service Company W OEHor^mdc,

16805 WCR 19 1/2, Platteville, Colorado 80651 f)w.

j

December 4, 1984Fort St. VrainUnit #1P-84515

Mr. Robert Martin, Regional AdministratorReactor Project Branch 1Region IV DEC -T 1984Nuclear Regulatory Commission y611 Ryan Plaza Drive, Suite 1000 '

uArlington, Texas 76011

ATTN: Mr. E. H. Johnson

REFERENCE: Facility Operating LicenseNo. OPR-34

Docket No. 50-267

Dear Mr. Collins:

Enclosed please find a copy of Licensee Event ReportNo. 50-267/84-012, Preliminary, submitted per the requirements of10 CFR 50.73(a)(2)(v).

Sincerely,

a

J. W. GahmManager, Nuclear Production

Enclosure

cc: Director, MIPC

JWG/djm

b

N Of

g#bV i

to n\\