ML18067A758

LER 97-010-00:on 970930,determined That Inadequacy in App R Analysis Resulted in Condition Outside Design Basis of Plant.Caused by Missing Cable in Circuit & Raceway Schedule. Developed New Evaluation Re ASD Valves Validation

ML18067A758
Person / Time
Site:	Palisades
Issue date:	10/30/1997
From:	Kozup C CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML18067A757	List: ML18067A756 ML18067A758
References
LER-97-010, LER-97-10, NUDOCS 9711050112
Download: ML18067A758 (5)

Text

,I I

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 I (4195) EXPIRES 4/30/98 I

ES'TlMATEl BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REOUEST: 50.0 HRS. REPORTED LESSONS LEARNED ARE INCORPORATED LICENSEE EVENT REPORT (LER) INTO THE LICENSING PROCESS ANO FED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION ANO RECORDS MANAGEMENT BRANCH (T-8 F33). U.S. "-'CLEAR REGULATORY COMMISSION, WASHINGTON, DC 2055$-

0001, AND TO THE PAPERWORK REDUCTION PROJECT (31~10ol, OFFICE OF (See reverse for required number of digits/characters for each block) MANAGEMENT ANO BUDGET. WASHINGTON, DC 20503 FACILITY NAME (1) CONSUMERS ENERGY COMPANY DOCKET NUMBER (2) Page (3)

PALISADES NUCLEAR PLANT 05000255 1of5 TITLE (4) LICENSEE EVENT REPORT 97-010 - INADEQUACY IN APPENDIX R ANALYSIS RES ULTS IN A CONDITION OUTSIDE THE DESIGN BASIS OF THE PLANT EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR I SEQUENTIAL NUMBER REVISION NUMBER MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 05000 FACILITY NAME DOCKET NUMBER

• 10 30 97 97 - 010 - 00 10 30 97 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 1.0 CFR§: (Check one or more) (11)

MODE (9) N 20.2201(b) 20.2203(a)(2)(v) 50. 73(a)(2)(i) 50.73(a)(2)(iii) 20.2203(a)(1) 20.2203(a)(3)(i) x 50. 73(a)(2)(ii) 50.73(a)(2)(x)

I POWER LEVEL (10)

I I 0 20.2203(a)(2)(i) 20.2203(a)(2)(ii) 20.2203(a)(3)(ii) 20.2203(a)(4) 50.73(a)(2)(iii)

50. 73(a)(2)(iv) 73.71 OTHER I

20.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v) Specify in Abstract below or 1:11s .*. 20.22031aH2Hivl 50.361cH2l 50.731aH2Hviil in NRC Form 366A LICENSEE CONTACT FOR THIS LER (12)

NAME Charles S. Kozup, Licensing Engineer TELEPHONE NUMBER (Include Area Code)

(616) 764-2241 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 113\

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS TONPRDS SUPPLEMENTAL REPORT EXPECTED (14\ MONTH DAY YEAR*

I YES If ves COMPLETE EXPECTED COMPLETION DATE

. x I NO EXPECTED SUBMISSION DATE 115\

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

A 10 CFR 50, Appendix R analysis concluded the simultaneous opening of two main steam line atmospheric steam dump valves (ASDVs) required termination of the steam generator blowdown by local manual actions within ten minutes. In the analysis, opening of two of the four main steam ASDVs occurred spuriously from a hot short. Recent reviews of the Appendix R analysis determined it should have accounted for all four main steam ASDVs and the turbine bypass valve (TBV) spuriously opening.

A new evaluation indicates that lotal manual actions must be completed within six minutes to close the ASDVs in the event of the App~ndix B fire scenario resulting in all four ASDVs and the TBV opening. A walk-through verification concluded that the ASDVs could be closed within six minutes.

The procedure has been revised and operator training of the procedure revision has been completed.

This event is reportable in accordance with 10 CFR 50.73(a)(2)(ii)(B) as a condition outside the plant design basis. The earlier Appendix R analysis contained errors which could have potentially placed the plant in a scenario which was not addressed with approved procedures.

9711050112 9 7 1030 a

~DR ADOCK 0 50002 PoR 5

--1 NRC FORM 366a U.S. NUCLEAR REGULATORY COMMISSION I!

4195 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION

~

FACILITY NAME 11 l DOCKET12l LER NUMBER 16)

CONSUMERS ENERGY COMPANY YEAR 1* SEQUENTIAL REVISION NUMBER NUMBER 05000255 5 PALISADES NUCLEAR PLANT 97 - 010 - 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

EVENT DESCRIPTION On September 30, 1997, the plant was in hor shutdown and the primary coolant system was at 534°F. An Appendix R Program review of the Off Normal Procedure (ONP) 25.2, "Alternate Safe Shutdown Procedure", and the electrical circuitry associated with the main steam line atmospheric steam dump valves (ASDVs) was being conducted. This review determined that Appendix R analysis, EA-APR-95-019, "Plant Response to Two Stuck-Open ASDVs Under Appendix R Conditions", did not account for all four ASDVs and the turbine pypass valve (TBV) spuriously opening as a result of a fire. The opening of all four ASDVs and the TBV was initially determined to be within the plant design basis and not reportable, based on engineering judgement that the ASDVs could be closed within ten minutes, and the blowdown was within the analyzed steam generator blowdown. A new evaluation of the condition, with all four ASDVs and the TBV spuriously opening from the same fire, identified that manual action was necessary to close the.

ASDVs within six minutes. On October 4, 1997, with the plant in cold shutdown, the condition was determined reportable under 10CFR50.73 as a condition outside the plant design basis.

The original circuit analysis did not conclude that all four ASDVs and* the TBV would open. The circuit analysis conclusion resulted from one cable not being included in the analysis. This cable, which was not identified on the circuit and raceway schedule (C&RS), ran between control room control panels, EC01 arid EC12. This cable was also not correctly identified on the schematic diagram and not factored into the original analysis. Therefore, when the circuit analysis was done for components in the cable spreading room and the control room, it was concluded that a hot short could affect only two ASDVs.

The steps for conducting a circuit analysis are summarized as follows:

1. Review the safe shutdown equipment list to determine the components required and their positions. .

2. For each component, review the applical..J1e. schematic diagram, and other diagrams and drawings as-required, and perform circuit analysis.

3. Using the cable and raceway schedule, obtain a list of all the cables associated with the scheme number identified for each component to be analyzed. Enter the cables on the circuit analysis worksheet.

4. Review each cable based on the cable connections in the electrical circuit to determine the effects of a fire induced short, hot short, open circuit, and short to ground, etc.

NRC FORM 366a U.S. NUCLEAR REGULATORY COMMISSION 4195 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME 11 \ DOCKETl2\ LER NUMBER 16\ PAGE CONSUMERS ENERGY COMPANY PALISADES NUCLEAR PLANT 05000255 YEAR I SEQUENTIAL NUMBER REVISION NUMBER 3 OF 5 97 - 010 - 00 TEXT {If more*space 1s required, use additional copies of NRC Form 366A) (17)

Upon completion of the circuit analysis, the raceways (cable trays and conduits) are located and verified for each cable. A functional requirements analysis is completed to* determine the time frame for operator actions, and a safe shutdown assessment is completed to determine the systems and methods used to achieve safe shutdown. Feasibility of manual actions are then assessed and procedures are revised as necessary to carry out the manual actions.

The review of the schematic diagrams and other drawings in step 2 (above) was done for the ASDV's scheme. The file drawings serve to identify the circuits shown on the cable and raceway schedule. Had the cable that is routed from EC01 to EC12, through the cable spreading room, been identified on the C&RS, step 3 would have captured the cable. Additionally, had the

$Chematic diagram identified the cable as. a field run cable, the cross checking against the C&RS would have identified a discrepancy that would have required resolution. In step 4, an evaluation of the effects of a fire on that cable would have occurred. Since the cable did not appear on the C&RS and was not properly identified on the schematic diagram, identifying it and its potential failure was dependent on the reviewers' knowledge of the operation of the ASDVs and the rigor in which the reviewers checked the schematic diagrams.

Although this event resulted from an omission on the C&RS, we have a high level of confidence in the C&RS as it pertains to these Appendix R circuits. This confidence is due to the scope of the work conducted in the Appendix R enhancement project to ensure completeness of the Appendix R circuits in the C&RS. Significant resources in the Appendix R enhancement project were directed at ensuring that circuits were correctly indicated on the C&RS. Circuits were verified by multiple references. The C&RS circuits were checked against plant schematic drawings. The cable routing was checked using raceway location drawings and all routings were checked to verify that the routing was feasible and logical. If a discrepancy resulted, it was resolved via further drawing reviews, modification package reviews, walkdowns, or tone tracing wires.

Because of this prior work to verify cable routing and correct the identified deficiencies, we have a high degree of confidence that the Appendix R circuits are where the C&RS indicates.

Additional opportunities to identify and disposition the condition resulting in spurious opening of all four ASDVs occurred in the follow-up assessments leading to the manual actions feasibility analys-is~ During these--assessments, Appendix R systems reviews should have raised questions on. the comprehensive effects of a fire on all four ASDV control circuits. During the manual actions feasibility analysis, it was recognized that a quick-open circuit for the ASDVs and the TBV may be affected. Informal discussions ensued where it was concluded that the opening of all four ASDVs and the TBV was acceptable; a decision erroneously reached by considering the timing for closing all four ASDVs on an analysis conducted for a plant response to two stuck open ASDVs. Neither the recognition of the unanalyzed condition, nor its resolution were brought to the attention of

i

-.. , - ::..-*-., *;,I NRC FORM 366a U.S. NUCLEAR REGULATORY COMMISSION I 4195 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION

[;]

FACILITY NAME 11 l DOCKETl2\ LER NUMBER 6l CONSUMERS ENERGY COMPANY PALISADES NUCLEAR PLANT 05000255 YEAR I SEQUENTIAL NUMBER REVISION NUMBER 5

97 - 010 - 00 TEXT (If more space 1s required, use add1t1onal copies of NRG Form 366A) (17) other Appendix R staff. As a result, no action was taken to update the engineering analysis to account for four ASDVs opening. Although accounting for all four ASDVs opening in the feasibility analysis, due to the lack of communication, ONP 25.2 was inappropriately revised to indicate that closing one or two ASDVs, versus all four, may be necessary within ten minutes.

ANALYSIS OF EVENT The probability of a control room or cable spreading room fire resulting in the ASDVs spuriously opening due to a hot short affecting this particular circuit is relatively low. The significance of the condition is that the analysis did not fully account for the effects of an Appendix R fire scenario in the control room or cable spreading room. As a result, the analysis did not adequately evaluate the severity of the transient that may have been caused by the fire. Without timely manual action to close the ASDVs and subsequently initiate auxiliary feedwater, the opening of all ASDVs and the TBV could lead to blowdown of the steam generators and rapid cooling of the primary coolant

. system. After the steam generators blow dry, a loss of natural circulation core cooling would occur. A loss of core cooling would create voiding in the upper head area of the reactor vessel and could lead to fuel clad damage. This fire scenario, without intervening timely manual action, is not acceptable. Therefore, the analysis did not meet the Appendix R requirements.

CAUSE OF THE EVENT The cause of this event is considered to be the missing (unidentified) cable in the C&RS that is routed in the cable spreading room from control panel EC01 to control panel EC12. This cable is also not identified as a field run cable on the circuit diagram. . In this case, cross checking the C&RS with the schematic drawings to verify circuits was not sufficient to prevent the error from occurring.

A contributing factor is that the systems review did not determine the comprehensive effects of a fire on the ASDV control circuit. A second contributing factor to this evenf is that during the

• manual adions feasibility a*nalysis, neither the recognition nor resolution 0fthe potential-condition where four ASDVs could spuriously open, was sufficiently communicated to the remainder of the Appendix R project personnel. Because others on the project were not aware of the condition, the need to revise the analysis for the plant response to two stuck open ASDVs was not identified.

Timing for the manual actions necessary to close the ASDVs was , therefore, based on an inappropriate analysis, and the changes made to procedure ONP 25.2 were inadequate.

I 1

• I i

I NRC FORM 366a U.S. NUCLEAR REGULATORY COMMISSION 4195 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION

~

FACILITY NAME f1 I DOCKETl2\ LER NUMBER 61 CONSUMERS ENERGY COMPANY PALISADES NUCLEAR PLANT 05000255 YEAR I SEQUENTIAL NUMBER REVISION NUMBER 5

97 - 010 - 00 TEXT (If more space 1s required, use add1t1onal copies of NRC Form 366A) (17)

CORRECTIVE ACTIONS COMPLETED The following actions have been completed:

1. The new evaluation which established the six-minute manual action closure requirements for the ASDVs has been validated on the plant simulator to verify the time necessary to accomplish the manual actions for coping with all four ASDVs opening in an Appendix R fire scenario.

2. Operations has validated that the manual actions to close the ASDVs within six minutes can be accomplished.

3. Off Normal Procedure ONP 25.2 has been revised to ensure timely completion of manual actions to close the ASDVs, and subsequently initiate auxiliary feedwater, in the event of a fire and opening of four ASDVs.

4. Operators have been trained on the revision to ONP 25.2 that incorporated changes for initiating closure of all four ASDVs.

5. The site. expectations for the communication of issues and concerns has been discussed with the present Appendix R program staff.

CORRECTIVE ACTIONS TO BE COMPLETED The following actions will be completed:

1.* A revision to the circuit and raceway schedule and to the schematic diagram will be completed to identify the cable in the ASDV circuit that is routed from control panel EC01 to control panel EC12.

2. The Appendix R Engineering Analysis will be updated with the results of-the evaluation that four ASDVs and the Turbine Bypass Valve (TBV) could possibly open in the postulated fire scenario.

3. Following completion of the Appendix R analyses validation, a cumulative review of the manual actions required by Operations personnel will be conducted.