ML20137W989

Forwards Addendum to 860219 Summary Rept Re Resolution of Issues from 851226 Reactor Trip,Replacing Page 41.Addendum Addresses Remote Isolation Capability for Main Steam Lines, Independent of ICS Power & Controls

ML20137W989
Person / Time
Site:	Rancho Seco
Issue date:	02/24/1986
From:	Reinaldo Rodriguez SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Martin J, Miraglia F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V), Office of Nuclear Reactor Regulation
References
RJR-86-082, RJR-86-82, TAC-60462, NUDOCS 8603040245
Download: ML20137W989 (4)

Text

!

i

$SMUD 19 SACRAMENTO MUNICIPAL UTILITY DISTRICT 6201 S Street. P.O Bo= 15830. Sacramento CA 95852 1830,1916:452 3211 AN LLE CIHIC SYS T EA1 SE HVING T HL HL AH I W C AW (wd A

'.M rq 7 7 ,s p: , ,,..

RJR 86-082 3

February 24, 1986 JB MARTIN ADMINISTRATOR DIRECTOR OF NUCLEAR REACTOR REGULATION US NUCLEAR REGULATORY COMMISSION ATTENTION FRANK J MIRAGLIA JR DIRECTOR REGION V PWR-B DIVISION OFFICE OF INSPECTION AND ENFORCEMENT US NUCLEAR REGULATORY COMMISSION 1450 MARIA LANE SUITE 210 WASHINGTON D C 20555 WALNUT CREEK CA 94596 DOCKET 50-312 RANCHO SECO NUCLEAR GENERATING STATION UNIT NO 1 RESOLUTION OF ISSUES REGARDING THE DECEMBER 26, 1985 REACTOR TRIP - ADDENDUM 1

Reference:

1) JB Martin to RJ Rodriguez - Confirmatory Action Letter -

Return of Rancho Seco to Power Operations - December 26, 1985

2) RJ Rodriguez to JB Martin and FJ Miraglia - Schedule for Return of Rancho Seco to Power Operations f rom Transient of December 26, 1985 - January 24, 1986

3) RJ Rodriguez to JB Martin and FJ Miraglia - Resolution of Issues Regarding the December 26, 1985 Reactor Trip -

February 19, 1986 Please incorporate the enclosed pages into your copy of the District's Summary Report, Reference 3, in place of the existing page 41. This aridendum addresses the Remote Isolation capability for the Main Steam Lines, independent of ICS power and controls.

/yR. J. RODRIGUEZ v ASSISTANT GENERAL MANAGER, NUCLEAR Attachments 8

\

%ii'344 $1 x & a1 RANCHO SECO NUCLEAR GENERATING STATION r 14440 Twin Cities Road, Herald, CA 95038 9799;(209) 333 2935

~

VI. 3. (Continu:d)

It became clear in meeting the requirements of NUREG 0737, that the number of modifications imposed in Rancho Seco would exceed the electrical capacity of its existing emergency diesel generators. The District decided in 1980-81 to purchase two additional diesel generators to augment the existing system. The District originally

. planned the installation of these new generators during the Cycle 7 refueling outage. This schedule was compatible with the installation of the majority of the TMI modifications, as well as the implementation of EFIC. The diesels purchased were made by TOI and the District, as well as several other utilities, were forced into a major TDI generator requalification program as a result of design problems discovered on the Shoreham plant diesels. This requalification program required both time (several years) and resources to complete. The current schedule will have the diesels operational during the Cycle 8 refueling outage.

Since EFIC, and several other modifications, were tied to the installation of the diesels, the Olstrict was forced to defer implementation of EFIC. This delay also afforded the Olstrict time to take a closer look at EFIC as installed at CR-3 and ANO-1.

Because of some initial startup and operational difficulties at these installations, the District decided on installing the indication portions of EFIC during Cycle 8. This would allow the operators to gain familiarity with the system during an operating cycle.

Likewise, the District has been interfacing with the staff of ANO-1 to minimize any operational problems and benefit from the ANO experience, as the District's EFIC will closely resemble the ANO EFIC.

In October 1985, the District committed to accelerate implementation of EFIC. The District outlined the specifics of the EFIC implementation in a letter to the NRC dated January 17, 1986. This implementation will result in the majority of the EFIC actuation and control functions being operational at the completion of the Cycle 8 refueling outage.

4. Other Modifications Many of the event related recommendations deal with potential modifications. These are beyond the requirements for startup and are being evaluated on their merits for subsequent incorporation. Some potential modifications, which have been determined to either be unnecessary or inappropriate, are discussed below.

addendum 1

VI. 4. 1. Remote Isolation Capability for Main Steam Lines The Rancho Seco NSS design does not incorporate Main Steam

. Isolation Valves (MSIVs), thus, it relles upon the capability to remotely isolate the main steam loads at each point where they interface with the main steam lines. Through December 26, 1985, the six Atmospheric Dump Valves and the four Turbine Bypass Valves, were not independent of the ICS. Subsequently, the controls to these ten valves have been modified to make their operation independent of the ICS. The following discussion addresses the remaining loads on the steam mains.

As shown on the accompanying Figure 1, the Main Steam lines are provided with remotely controlled motor operated valves (MOVs) which allow the control room operator to isolate each branch or load from its steam main. These valves are powered by diesel generator backed 480 VAC power. Their control circuits are individually powered through the associated power breaker, hence, there is no interaction or relationship to the ICS, At the end of the main steam lines are the four Turbine Throttle Valves which accomplist the Turbine Trip function. These valves are Electro-Hydraulic in that they are held open by hydraulic pressure. The turbine trip signal is developed in the Reactor Protection System (RPS), which then causes the turbine to trip independent of the ICS.

The only other device effected by the ICS is the Aurillary Steam lieader control station. As already discussed, this device will open to 50% upon Loss of ICS power. Should the operator elect to isolate that line, NOVs are provided which are powered and controlled independent of the ICS.

By providing control to these valves, independent of the ICS, the control room operator can ef fectively isolate the main steam loads, should that become necessary or desirable. Walkdown of the individual steam lines identified eight steam traps, which are piped into the main condenser, which do not have remote isolation capability. These lines are too small to constitute an overcooling load on the NSS, as such they do not require remote isolation capability, nor are they ef fected by ICS power or operation.

VII. ROOT CAUSE(S)

The Rancho Seco incident Analysis Group (IAG) has responsibility to determine the " root cause" of problems or events at the facility. This involves addressing the progrannutic causes as well as the direct causes unique to specific occurrences.

-41a-addendum 1

=

e >

• • ot 1 esee.:

seanen mat ,ei,,, w a sas 2 Y

?'. -

m 2 W

< N d

• C E

1

. 2

1 .

18,9g

& ew 05-g

@-1 E9'MIWMfAh'*."E.lM P.'Ma , ff.icMnVM*,;c.~g+ ,,*g

_ c

, -(nq -

-T C :: pl

= e. . . -

1. , , i 3 -2 s s.  !

i .l i ia e __ -tc. -

8,.

a r 9,( +

- e p.-

3 pM [ elh i5 M ,% +-

.- h, (. O D . s x a' cvb*

s e e .

l I  : .. ._

.:. %: g! "To E

8, x Ir y @.-

3 ) 3 *

• d .g

./

~

s

./

% )-C gE

• Y 2

h: s:sI-g u h s 5 -

j m miul T

g Q-j -

- f "ows e," "e) @

u. --t:-- .

s ,,

g u --

i, *

,J't' J W , -. . .,. .. J  !:

leEl .m=. h  ;,

Ir .

-=

15

.f, r r o. .,

(

= e-I i --q ,

b ,

E

!!!il . .

j=i M -

ol.I E GH: I!

. =

8 - .

-t. .

I t

I

-m-_ m o