ML20045E225

LER 93-012-00:on 930529,unplanned PCIS Group I Isolation Signal Occurred While Opening MSIV During Startup,Resulting in Automatic Closing of Related Valves.Caused by Licensed Operator Error.Group 1 Isolation reset.W/930625 Ltr

ML20045E225
Person / Time
Site:	Pilgrim
Issue date:	06/25/1993
From:	Boulette E, Munro W BOSTON EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BECO-LTR-93-80, LER-93-012, LER-93-12, NUDOCS 9307010266
Download: ML20045E225 (5)

Text

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ff 10 CFR 50.73 BOSTON EDISON Pilgrim Nuclear Power Station Rocky Hdi Road Plymouth, Massachusetts o236o E. T. Boulette, PhD Senior Vice President-Nuclear June 25 , 1993 BECo Ltr. 93- 80 U.S. Nuclear Regulatory Commission Attn: -Document Control Desk Washington, D.C. 20555 Docket No. 50-293 License No. DPR-35 The enclosed Licensee Event Report (LER) 93-012-00, " Group 1 Isolation During Startup While Opening Main Steam Isolation Valve", is submitted in accordance with 10 CFR Part 50.73.

Please do not hesitate to contact me if there are any questions regarding this report.

'l bC E. T. Boulette, PhD WJM/bal

Enclosure:

LER 93-012-00 cc: Mr.- Thomas T. Martin Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Rd.

King of Prussia, PA 19406 Mr. R. B. Eaton Div. of Reactor Projects I/II Office of NRR - USNRC One White Flint North - Mail Stop 14D1 11555 Rockville Pike Rockville, MD 20852 Sr. NRC Resident Inspector - Pilgrim Station

. Standard BEco LER Distribution 010032 9307010266 930625 /

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NRC FOnM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 (5+921 EXPIRES 5/31/95

, FSTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS LICENSEE EVENT REPORT (LER) 2"*O G M E R M ETWO L O C AND RECORDS MANAGEMENT BRAfCH (MNBH T714), U.S. NUCLEAR REGULATORY COMMIPSiON, WASHINGTON, DC 205550001, AND TO THE PAPERWORK REDUCTION PFnECT (31540104), OFTICE (See reverse for riumber of digite/charriers for each block) OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) l PAGE(3)

PILGRIM NUCLEAR POWER STATION 05000 - 293 g 1 of 5 YiTLE (4)

Group 1 Isolation During Startup While Opening Main Steam isolation Valve EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

SEQUENTIAL REVIS10N F ACluTY NAME DOCKET NUMBER MOMH DM YEAR YEAR NUMBER NUMBER MONTH DAY YEAR N/A 05000 FACIUTY NAME DOCKET NUMBER 05 29 93 93 012 00 06 25 93 N/A 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REOUIREMENTS OF 10 CFR S (Check one or more)(11)

IN 20.402(b) 20.405(c) X 50.73(a)(2)(iv) 73.71(b)

PO 20.405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v)

LE E 001 73.71(c) 0)

20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER 20.405(a)(1)(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) g7ggg (g ,c,,y 20.405(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) ytgige,cy 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) Form 366A)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (include Area Code)

William J. Munro - Sr. Compliance Engineer (508) 747-8474 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER SUPPLEMENTAL REPORT EXPECTED (14) *"'" D# "

EXPECTED YES NO SUBMISSION i e yes, compeie EXPECTED SUBMISSION DATE)

X DATE (15) j ABSTRACT On May 29, 1993 at 0614 hours0.00711 days <br />0.171 hours <br />0.00102 weeks <br />2.33627e-4 months <br />, an unplanned Primary Containment Isolation Control System  ;

(PCIS) Group 1 isolation signal occurred while opening a Main Steam Isolation Valve (MSIV) during startup. The signal resulted in the automatic closing of the related_ valves. The isolation signal was caused by a high Reactor Vessel (RV) water level (+48 inches). The high water level occurred while opening an MSIV that caused a swell (expansion) of RV water. The root cause of the event was licensed operator error. While attempting to equalize steam line pressures, a misunderstood communication occurred between an operator and the Nuclear Watch Engineer regarding the RV water level and RV pressure. This caused the NWE to leave the 'C' inboard main steam isolation valve open longer than planned, resulting in a relatively greater decrease in RV pressure and a corresponding rise in RV water level to the point (+48 inches) where the high water level isolation occurred.

Contributing to the event was the fact that the MSIVs were opened with RV water level starting slightly higher than that directed by the applicable procedure and several manual isolation valves downstream of the MSIVs, thought to be closed, were open resulting in increased steam flow through the MSIV when opening the valve. The importance of procedural adherence and clear communication was stressed by the Chief Operating Engineer to the applicable Watch Engineer. Procedure 2.2.92 will be revised to ensure that applicable valves are checked in the event outboard steam pressure does not build up.

This event occurred during a startup with the reactor mode selector switch in the STARTUP position. The control rods were in a partially withdrawn position. The RV water temperature was 350 degrees Fahrenheit and the RV pressure was 140 psig. The reactor l power level was approximately one percent. This report is submitted in accordance with '

10 CFR 50.73(a)(2)(iv). This event posed no threat to the health and safety of the public.

NnC rORu a m i

NRC FORM 366A U.S. NUCLEAR HEGULATORY COMMISSION APPROVE BY O 8 0 3150-0104-LICENSEE EVENT REPORT (LER) fraL"Taa"iu"a L "J' %'a g gng g gEu g g o gnu TEXT CONTINUATION 8 em s ANo mGgt OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20501 FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) - PAGE (2)

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R 20f 5 PILGRIM NUCLEAR POWER STATION 05000-293 93 - 012- 00 VEXT (if more space is required, use additional copies of NRC Form 366A)(17)

EVENT DESCRIPTION .

On May 29,1993 at 0614 hours0.00711 days <br />0.171 hours <br />0.00102 weeks <br />2.33627e-4 months <br />, an unplanned Primary Con'tainment Isolation Control System '

(PCIS) Group 1 (one) isolation signal occurred. The signal was the result of'a high water .

level-in the Reactor Vessel that occurred while opening Main Steam System isolation valve:

(MSIV) A0-203-10. The MSIV was being opened with a differential pressure of approximately 140 psid across the seat of the MSIV.

The signal resulted in the following responses:

• The outboard MSIVs A0-203-2A/B/C/D, in the open position, closed automatically.

• The inboard MSIVs A0-203-1A/B/0, in the closed position, remained. closed. .

• The inboard MSIV A0-203-10 closed automatically.

• The. inboard and outboard Main Steam drain line isolation valves M0-220-1 and M0-220-2, in the open position, closed automatically. 1

• The inboard and outboard Sample System Valves A0-220-44 and -45, in-the open position, closed automatically. 't After reducing the RV water level, the isolation signal was reset.

Problem Report 93.9279 was written to document the. event. The NRC Operations Center was notified in accordance with 10 CFR 50.72 at 0810 hour0.00938 days <br />0.225 hours <br />0.00134 weeks <br />3.08205e-4 months <br />s:on May 29, 1993.

This event occurred during a startup with the reactor. mode selector switch in the STARTUP position. The control rods were in a partially withdrawn position. The Reactor' Vessel- '

(RV) water temperature was 350 degrees Fahrenheit and the RV pressure was 140 psig. The.-

reactor power . level was approximately one percent. The RV water level was being ~ manually ; J controlled and was approximately-+26 inches just prior to'the event.

CAUSE The cause for the high RV water level trip signal was the swell (expansion); of.the RV.

water that. occurred when the "C" inboard MSIV A0-203-1C.was opened with the."C" outboard-MSIV A0-203-2C in the open position. The root'cause was utility licensed operator error. 1 Following refueling outage No. 9.the plant was stsrted up with MSIVs closed to perform pre-op testing on the main turbine. .On May 29, 1993 operations personnel were performing-activities to restart the plant using Procedure 2.1.3,(Rev. 23) "Startup With MSIVs closed ,

Rx Pre'sures Less Than 600 psig." The Nuclear Watch Engineer (NWE) had indicated.that the-inboard MSIVs would have to be opened prior to pressurizing the reactor greater ~than 150 psig.  ;

NRC FCFW 366A @e2)

. - 1 RRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSloN APPROVED BY OMB NO,3150-0104 r s-m EXPIRES 5/31/95

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YEAR R MB 30f 5 PILGRIM NUCLEAR POWER STATION 05000-293 93 - -012- 00 TEXT (if more space is required, use additional copies of NRC Form 366A)(17)

The operators were using Procedure 2.2.92 (Rev. 25) " Main Steam Isolation and Turbine Bypass Valves". Section 7.1 " Opening MSIVs with Reactor Pressurized" instructs the operators to open the outboard MSIVs, equalize the main steam header and reactor pressures within 50 psig and then open the inboard MSIVs one at a time. Procedure 2.2.92 also contains a CAUTION statement to maintain a lower initial RV water level in the low end of the normal operating range at less than 24" to account for " swell" during opening of the MSIVs.

The valve lineup was configured to drain condensed steam from the main steam lines.

Following a warm-up of the drain lines, drain valve M0-220-04 was closed in an attempt to pressurize the main steam lines and obtain a 50 psi differential across the MSIVs (50 psid is the preferred differential; a maximum of 200 psid is allowed). After an hour there was no increase in pressure.

After discussion with the Chief Operating Engineer a decision was made by the NWE to open the inboard MSIVs for short periods of time to pressurize the lines. The reactor pressure was 140 psig. Control room operators were assigned to monitor reactor water level and outboard steam pressure, and to announce the parameters as each MSIV was opened.

Following the individual opening of the "A" and "B" inboard MSIVs the reactor water level swelled from +28 inches to +43 inches and +28 inches to +39 inches for "A" and "B" MSIVs respectively. The pressure in the outboard steam lines increased only slightly. When the NWE opened the "C" inboard MSIV a misunderstood communication occurred. The NWE misunderstood the announced steam line pressure as the RV water level and did not close the "C" inboard MSIV. RV water swelled from approximately +26 inches to approximately +48 inches and thereby resulted in the event.

CONTRIBUTING CAUSE Failure to follow Procedure 2.2.92 by lowering the reactor water level to 26" vice 24" to account for " swell" during opening of the MSIVs.

When the next shift crew performed a review of the main steam lineup, the steam supply valve-(H0-170) to the electrolytic compression modules and the SJAE Regulator Bypass valve (H0-160) were found in the open position. In addition, the "A" primary jet steam supply valve was frozen in the open position. Failure to isolate these valves prevented steam pressure from building up in the outboard steam lines.

CORRECTIVE ACTION On May 29, 1993 the Group 1 isolation was reset per Procedure 2.2.125.1 Reset Of Primary And Secondary Isolations, water level was restored and downstream steam auxiliary valves were closed allowing downstream piping to pressurize.

Procedure 2.2.92 will be revised to ensure that applicable valves are checked in the event outboard steam pressure does not build up, we um umm

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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVEo BY OM8 NO.3150-0104 mm EXPlRES 5/31/95  ;

ESTlMATED BURDEN PER RESPONSE 'O COMPLV WITH THIS Di LICENSEE EVENT REPORT (LER) 1"3?%2fLsfEisjA O INF T TEXT CONTINUATION 35To"m cSou SS"8EsHS"oTTEANaNm -

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A discussion was held between the Operations Section Manager, the Chief Operating Engineer '

and the applicable Nuclear Watch Engineer to stress the importance of procedural adherence and clear communications.

This event will be reviewed with all operating crews during Licensed Operator j Requalification. training. -

SAFETY CONSE0VENCES This event posed no threat to the health and safety of the public.  ;

The purpose of the RV high water level isolation is to protect against rapid .

i depressurization due to malfunction of the pressure regulator system during.startup when y; RV pressure is below 880 psig. ~!

The high RV water level trip signal resulted from the swell .(expansion).of RV water that occurred when the Main Steam line 'C' outboard MSIV was opened. The closing of.the Group 1 (one) isolation valves was the designed response to the high RV water level.

This report is submitted in accordance with 10 CFR 50.73(a)(2)(iv) because the closing of isolation valves, although a designed response, was not planned.

SIMILARITY TO PREVIOUS EVENTS A review was conducted of Pilgrim Station Licensee Event Reports (LERs) submitted since-January 1984. The review was focused to LERs submitted in accordance with- .

i 10 CFR 50.73(a)(2)(iv) that involved a similar event resulting from a high RV water level.  :

The review identified events reported-in LERs 50-293/89-007-00 and 92-004-00.

For LER 92-004-00, three Group 1 isolations occurred during a shutdown on-March 26-27, 1992. The second isolation occurred on March 26, 1992, at 2129 hours0.0246 days <br />0.591 hours <br />0.00352 weeks <br />8.100845e-4 months <br />, after the PCIS Group I circuitry was reset and while opening the-MSIVs with the RV pressure at q 82 psig and RV water level at +29 inches. The cause was high RV water level due'~ to swell; '

Prior to opening MSIV A0-203-10, the Main Steam header pressure:and RV pressure was:

equalized within. 50 psig in accordance with procedure 2.2.92 (Rev. 24)- section-7.1.-

However, the RV water level (+29 inches) was greater than the desired level for opening an MSIV with-the RV pressurized. Corrective action taken-included revising Procedure 2.2.92 (to.Rev. 25) to maintain a lower initial RV water level in the " Low End" of the normalL '

operating range at less than 24"' prior to opening an MSIV.with the RV pressurized.to account for swell.

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FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (2)

YEAR ET MD R Sof 5 PILGRIM NUCLEAR POWER STATION 05000-293 93 - -012-- 00 TEXT (if rnore space is required, use additional copies of NRC Form 366A)(17)

For LER 89-007-00, a Group 1 isolation occurred during the power scension program on ~

February 11, 1989, at 0936 hours0.0108 days <br />0.26 hours <br />0.00155 weeks <br />3.56148e-4 months <br />. At the time of the event, the reactor power level was 0.8 percent, the reactor mode selector switch was in the STARTUP position, the RV pressure was 278 psig, and the RV water level was approximately +34 inches. The inboard MSIVs A0-203-1A/B/C/D were in the open position with the outboard MSIVs A0-203~2A/B/D in the closed position. The outboard MSIV A0-203-2C was being opened with differential pressure of approximately 150 psid in accordance with Procedure TP 87.-219 (Rev. 3), "MSIV Opening Test", step 10.5. The isolation was the result of a high RV water level (+48 inches) due to swell that occurred while opening the MSIV. The cause of the event included a procedure weakness in that the procedure did not indicate a high RV water level could occur as a result of the test and did not specify or recommend an initial RV water level for the test. Procedure TP 87-219 was subsequently retired.

ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) CODES The EIIS codes for this report are as follows:

COMPONENTS CODES Valve, isolation (MSIV) ISV t SYSTEMS Containment Isolation Control System (PCIS) JM Engineered Safety Features Actuation System (PCIS) JE Main Steam System SB NRC FORM 366A (5-82)

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