05000272/LER-1990-019-01, :on 900603,main Steam Line Isolation Actuation Occurred & Bistables for Low Steam Line Pressure Logic Tripped.Caused by Equipment/Design Concerns W/Sensing Lines. Design Mods Re Flow Instrumentation Underway

:on 900603,main Steam Line Isolation Actuation Occurred & Bistables for Low Steam Line Pressure Logic Tripped.Caused by Equipment/Design Concerns W/Sensing Lines. Design Mods Re Flow Instrumentation Underway

ML18095A327
Person / Time
Site:	Salem
Issue date:	07/03/1990
From:	Miller L, Pollack M Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-019-01, LER-90-19-1, NUDOCS 9007060239
Download: ML18095A327 (5)

LER-1990-019, on 900603,main Steam Line Isolation Actuation Occurred & Bistables for Low Steam Line Pressure Logic Tripped.Caused by Equipment/Design Concerns W/Sensing Lines. Design Mods Re Flow Instrumentation Underway

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)
2721990019R01 - NRC Website

text

1*

e i

() PS~G Public Service Electri_c and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem G.enerating Station U. s. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-70 DOCKET NO. 50-272 UNIT NO. 1 LICENSEE EVENT REPORT 90-019-00 July 03, 1990 This Licensee Event Report is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR 50.73(a) (2) (iv}.

This report is required within thirty (30) days of discovery.

MJP:pc Distribution Sincerely yours, L. K. Miller General Manager -

Salem Operations 95*2189 (10M) 12-89

""c l'er* *

~I.

U.1. NUCLU.11 lllCIULATOllY COMlllSIOlt

- OVID 0.. NO. 21111-0lCM LICENSEE EVENT REPORT (LEAJ TITLI 1'1 ESF Actuation:* Main Steamline Islolation Due To Equipment Design/Equipment Concerns IVENT DATE ltll Liii NUMBER Ill llEl'OllT DA TE 171 OTifEll FACILITIH INVOLVIO *I FACILITY NAMQ DOCKET NUMIERlll Of'ERATINO THll llEPORT II IU8MITTED 'URIUANT TO THE "EOUIREMENll OF 10 CFll §: (Ch<<lr ono °' morw of"" lollowlttfl 1111

--MOO--ET"ll_I _ _._4_._--t 20.4021~1 20.-lol

.,_2!

I0.72lall211111 l'OWE" I

. 20.-1*1111111 LEVEL 1101 0 01 0 20.40llllll111111 iA*= :::::::::

IO.Mlollll I0.31(01121 1--

I0.731*1121111 i--

I0.731111211111 I0.731al!21UHI I0.7'1all21M l50.7J_lall2lllll I0.7Jlall2llw!HllAI I0.7:1lall2llwllillll

-. I0.7:11al!211*1 LICENSEE CONTACT fOll THIS LEll (!II 7:1.71~1 7:1.71181 OTifEll 15-lfy In Abfowt Nlow *ntl In Tur. NRC,,_

3B6AJ NAME TELEPHONE NUlo!llEll AREA CODE M. J. Pollack -

LER Coordinator COMPLETE ONE LINE FOR EACH.COMPONENT FAILURE DEICllllED IN THll llll'ORT 11:11

CAUSE

SYSTEM COMPONENT MANUFAC.

TUR ER I

I I I

I I

I I

I I I I I I

IUPPLEMENTAL REPORT EXPECTED IHI f

YES (If yn. <0mplot1 EXPECTED SUtlMISSION DATE!

UITRACT (Lim/I ro 14()() ll>>C*. I.e.* epprox/mettly fir...n rl"fl**IPOCO rypewri,..n final 1111 I

I I

I I

I I I MANUFAC.

TUR ER I

I I

I I I EX,ECTED SUtlM1$$10N DATE 1151.

On 6/3/90 at 0712 hours0.00824 days <br />0.198 hours <br />0.00118 weeks <br />2.70916e-4 months <br />, a Main Steamline Isolation actuation MONTH

.DAY "fAll I

I I

occurred.

• At the time of the event, the Unit was in Mode 4 and heating up in preparation for startup.

The Main Steamline Isolation signal was generated upon completion of the High Steamline Flow coincident with Low Steamline Pres~ure logic (by design).

In Mode 4, the bistables for low steamline pressure are tripped due to plant conditions providing half of the logic signal required for Main Steamline Isolation.

The high steamline,flow logic was completed when the bistables for No. 11 and No. 12 Steam Generator (S/G) high steamline flow tripped.

Main Steamline Isolation is an Engineered Safety Feature (ESF).

The root cause of this event has been attributed to possible equipment/design concerns associated with the main steamline flow transmitter sensing lines.

The initial investigation by Maintenance personnel, to determine why the Nos. 11 and 12 S/G high steamline flow bistables tripped, did not identify any failed components.

A channel functional test, of the subject steam flow channels, was successfully completed.

. Steamline flow measuring.design concerns have previously been identified via LER 272/88-017-01 (i.e., steamline flow measurement drift concern).

Engineering believes that the drift concern and this recent event appear to have a related cause.

Design modifications, to correct the main steamline flow instrumentation concerns, are under development.

NFIC Form JSe 19.aJ>

LICENSEE EVEN'!' REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 DOCKET NUMBER 5000272

PLANT AND SYSTEM IDENTIFICATION

Westinghouse

- Pressurized Water Reactor LER NUMBER 90-019-00 PAGE 2 of 4 Energy Industry Identification System (EIIS) codes are identified in the text as {xxl IDENTIFICATION OF OCCURRENCE:

Engineered Safety Feature Actuation; Main Steamline Isolation Due to Equipment/Design Concerns Event Date:

6/03/90 Report Date:

7/03/90 This report was initiated by Incident Report No.90-369.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 4 (Hot Shutdown); Reactor in preparation for startup Tevg at approximately 270°F and increasing DESCRIPTION OF OCCURRENCE:

On June 3, 1990 at 0712 hours0.00824 days <br />0.198 hours <br />0.00118 weeks <br />2.70916e-4 months <br />, a Main Steamline Isolation actuation

{JEI occurred.

At the time of the event, the Unit was in Mode 4 (Hot Standby) and heating up in preparation for startup.

The Main Steamline Isolation signal was generated upon completion of the High Steamline Flow coincident with Low Steamline Pressure logic (by design).

In Mode 4, the bistables for low steamline pressure are tripped due to plant conditions providing half of the logic signal required for Main Steamline Isolation.

The high steamline flow logic was completed when the bistables for No. 11 and No. 12 Steam Generator (S/G) high steamline flow tripped..

Main Steamline Isolation is an Engineered Safety Feature (ESF).

• Therefore, on June 03, 1990 at 0840 hours0.00972 days <br />0.233 hours <br />0.00139 weeks <br />3.1962e-4 months <br />, the Main Steamline Isolation signal event was reported to the Nuclear Regulatory Commission in accordance with Code of Federal Regulations 10CFR 50.72(b) (2) (ii).

APPARENT CAUSE OF OCCURRENCE:

The root cause of this event has been attributed to possible equipment/design concerns associated with the main steamline flow transmitter sensing lines.

The initial investigation by Maintenance personnel, to determine why the Nos. 11 and 12 S/G high steamline flow bistables tripped, did not identify any failed ~omponents.

A channel functional test, of the

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1 APPARENT CAUSE OF OCCURRENCE:

DOCKET NUMBER 5000272 (cont'd)

LER NUMBER 90-019-00 subject-steam flow channels, was successfully completed.

PAGE 3 of 4 The Salem design arrangement of a main steamline flow differential pressure measurement system includes two (2) taps (to provide 100%

redundancy) on the high and low pressure side of the main steamline venturi.

Attached to the taps are 1" manual globe valve~.

Steam is directed through l" pipe to condensate pots located near the high pressure tap.

The steam is then. directed to the Rosemount model 1153HD5 differential pressure transmitters via a 3/8" line.

Steamline flow measuring design concerns have previously been identified vi.a LER 272/88-017-01.

That LER addresses steamline flow measurement drift when the Unit is at power.

Engineering believes that the drift concern and this recent event appear to be related to design concerns associated with the transmitter sensing lines.

Possible causes of these events are discussed in a detailed study which had been completed in support of LER 272/88-017-01.

ANALYSIS OF OCCURRENCE:

Main Steamline Isolation protection is applicable only in Mode 1 Power Operation}, Mode 2 (Critical Operation}, and Mode 3 (Hot Standby}. It is designed to ~itigate the consequences of various design base accidents including main steamline rupture and steam generator primary to secondary tube rupture.

In Mode 4, the reactor is subcritical with Tavg greater than 200°F but less than 350°F.

Decay heat is removed either by the Residual Heat Removal system or via steaming from the steam generators.

Makeup water to the S/Gs can be supplied by either a Condensate Pump or by an Auxiliary* Feedwater Pump.

In Mode 4, the Auxiliary Feedwater System {BAJ is not required to be oper~ble.

During this event, decay heat removal was accomplished using the Residual Heat Removal (RHR) System {BPI via No. 11 RHR Pump.

When*

the Main Steamline Isolation signal was actuated, the four MS7 Main Steamline Drain Valves, open in support of main steamline warmup (procedure IOP-2), went closed as ~esigned.

The other valves which would close on a Main Steamline Isolation signal were already closed.

Since this event was not the result of an actual plant need for Main Steam Isolation, this event did not affect the health or safety of the public.

However, since Main Steam Isolation is an ESF system,*

this event is reportable to the Nuclear Regulatory Commission in accordance with Code of Federal Regulations 10CFR50.73(a} (2) (iv}.

CORRECTIVE ACTION

Design modifications to correct the main steamline flow instrumentation concerns are under development for implementation (as

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 1

CORRECTIVE ACTION

(cont'd)

DOCKET NUMBER 5000272 LER NUMBER 90-019-00 per the corrective actions to LER 272/88-017-01).

MJP:pc SORC Mtg.90-079 General Manager -

Salem Operations PAGE 4 of 4