05000315/LER-1998-029, :on 980422,SFP Ventilation Sys Was Noted Inoperable.Caused by Design Deficiency.Safety Evaluation Successfully Performed & Appropriate Surveillance Testing Completed

:on 980422,SFP Ventilation Sys Was Noted Inoperable.Caused by Design Deficiency.Safety Evaluation Successfully Performed & Appropriate Surveillance Testing Completed

ML17334A764
Person / Time
Site:	Cook
Issue date:	06/26/1998
From:	Malin D, Sampson J INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-98-029, LER-98-29, NUDOCS 9807020058
Download: ML17334A764 (8)

LER-1998-029, on 980422,SFP Ventilation Sys Was Noted Inoperable.Caused by Design Deficiency.Safety Evaluation Successfully Performed & Appropriate Surveillance Testing Completed

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3151998029R00 - NRC Website

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Amencan tleclnc Vower Cook Nuclear Plant One Cook Place Bndgman, Ml49106 6164655901 June 26, 1998 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Operating Licenses DPR-58 Docket No. 50-315 Document Control Manager:

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NRC Fprm 366 e 4-95)

U.S. NUCLEAR REGULATORYCOMMISSION LICENSEE EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

APPROVED BYOMB NO. 51$0410$

EKPIRES OU50r5$

ESTLVIATED BURDEN PER

RESPONSE

TO COMPLY WITH TISS MAI43ATORY INFORMATIONCOIAECTIONREOUEST'. 50.0 HRS. REPORTED lESSONS LEARNED ARE INCORPORATED INTO THE UCENSSIG PROCESS AND FEO BACK TO UIDUSTRY. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATIONAND RECORDS MANAGEMENTBRANCH (T4 Fss), U.S. NUCLEAR REGUlATORY COMMISSIOIL WASHINGTON.

OC 205554001, ANO TO THE PAPERWORK REDUCTION PROIECT (51500101), OFFICE OF MANAGEMENTAND BUDGET,WASISNGTOILDC 20505 FACILITYNAME(1)

TITLE(4)

Cook Nuclear Plant Unit 1 DOCKET NUMBER (2) 50-315 PAGE (3) 1 of3 Spent Fuel Pool Ventilation Inoperable Due to Original Design Deficiency EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILITIESINVOLVED(8)

MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REVISION MONTH NUMBER DAY YEAR A ILITYNAM Cook Unit 2 ACILI NAM O

NUM 50-316 CKET NUMBER 04 22 98 98

029 00 06 26 98 OPERATING MODE (9) 20.2201 (b) 20.2203(a)(2)(v) 50.73(a)(2)(i) 50.73(a)(2)(viii)

THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR li: (Check one or more) (11)

POWER LEVEL(10) i t

00 20.2203(a)(1) 20.2203(a)(2)(i) 20.2203(a)(2)(ii) 20.2203(a)(2)(iii) 20.2203(a)(2)(iv) 20.2203(a)(3)(i) 20.2203(a)(3)(ii) 20.2203(a)(4) 50.36(c)(1) 50.36(c)(2)

LICENSEE CONTACT FOR THIS LER (12) 50.73(a)(2)(ii) 50.73(a)(2)(iii) 50.73(a)(2)(iv) 50.73(a)(2)(v) 50.73(a)(2)(vii) 50.73(a)(2)(x) 73.71 OTHER poesy VIAostrsor oerovr or h NRC Form SSSA Mr. Douglas Malin, Nuclear Fuels Manager TELEPHONE NUMBER(Indude Arse Code) 616/697-5065 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPROS

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS SUPPLEMENTAL REPORT EXPECTED (14)

YES (ItYes, complete EXPECTED SUBMISSION DATE).

X NO EXPECTED SUBMISSION DATE (15)

MON H Abstract (Limitto 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

In April 1998, with Units 1 and 2 in Mode 5, plant personnel writing the Radiation Monitoring System Design Basis Document (DBD) questioned a statement made in response to Question 9.4 of the SAR. This question requested evidence that the response time of the charcoal absorber bypass damper after a high radiation signal was received was adequate to prevent a p'otential "puffrelease" to the environment. After researching existing documentation and performance of a scoping calculation, it was determined that the 3 second response time of the bypass damper was unacceptable since a release would reach the bypass damper in less than 3 seconds, thus rendering the Spent Fuel Pool Ventilation system inoperable.

Since this condition was previously unknown, no compensatory actions had been historically taken.

On May 27, 1998, this condition was determined to be reportable under 10CFR50.73(a)(2)(ii), as operation prohibited by the plant's Technical Specifications.

The root cause of this condition is a design deficiency, which has been present since plant construction.

The Spent Fuel Pool Ventilation system was declared inoperable.

The analysis of record for fuel handling accidents will be updated, as will the applicable section(s) in the UFSAR. Once the analysis has been updated, a 10CFR50.59 Safety Evaluation successfully performed, and the appropriate surveillance testing completed, the ventilation system will be declared operable.

Evaluation of this condition determined that even without the charcoal bed in service, the consequences of a postulated fuel handling accident are bounded by the current analysis of record.

Therefore, this condition was determined to be of no

safety significance

NRC FORM 366 (4-95)

NRC ORM 366A (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION FACILITYNAME(1)

Cook Nuclear Plant Unit 1 DOCKET NUMBER(2) 50-315 YEAR 98 LER NUMBER (6)

SEQUENTIAL NUMBER 029 REVISION NUMBER 00 PAGE (3) 2of3 TEXT (tfmore space is required, use additional copies ofNRC Form (366A) (1 7)

CONDITION PRIOR TO EVENT

Unit 1 was in Mode 5, Cold Shutdown Unit 2 was in Mode 5, Cold Shutdown

DESCRIPTION OF EVENT

In April 1998, plant personnel writing the Radiation Monitoring System (RMS) Design Basis Document (DBD) questioned the required response time of the Spent Fuel Pool Area monitor, known as R-5. Documentation could not located that supported the following statement made in response to Question P9.4 in the SAR:

"Exhausted air from the spent fuel pit willreach the charcoal filter bypass dampers in 4 seconds (based on the shortest path). The time elapsed from receiving a high radiation signal at the radiation monitor to the full shut position of the carbon filter bypass damper is less than 3 seconds."

The investigation revealed that there is little existing documentation on this original design feature. After an extensive search, it was determined that no information could be located which supported, or provided a basis for, the statement in the SAR.

A scoping calculation was performed for the time expected for a release from the pool to reach the dampers.

This calculation indicated that the time was less than 1 second, much less conservative than the 4 seconds stated in the SAR.

Since the response time for the combination of monitor and bypass damper movement is stated to be less than 3 seconds, and no test data indicating that it is faster than 1 second could be located, the system was considered to be inoperable.

CAUSE OF EVENT

This condition is attributed to a deficiency in the original design.

As no documentation of the original postulated air transport time versus time for damper operation could be located, it is not possible to determine the basis for the design of the system.

ANALYSISOF EVENT On May 27, 1998, with both Unit 1 and Unit 2 in Mode 5, it was concluded that this event was reportable under 10CFR50.73(a)(2)(i)(B), as an operation prohibited by the plant Technical Specifications.

This conclusion was reached because the Spent Fuel Pool Ventilation system was inoperable from time of plant startup and has remained inoperable.

Technical Specification 3.9.12, which prohibits fuel movement with the system inoperable, was violated whenever fuel was moved without the charcoal filter being in service. Although the Spent Fuel Pool Radiation Monitor successfully passed its surveillance testing, the system responded in a time frame greater than assumed for the design basis.

Evaluation of this condition revealed that the charcoal filterserves contributes little to the lowering of radiation levels released to the environment as a result of a fuel handling accident.

Even without the benefits of charcoal absorption, the consequences of such an accident are bounded by the current analysis of record for a fuel,handling accident in containment.

As an ample margin exists between the bounding analysis value and the 10CFR100 limits, this condition has been determined to be of no safety significance.

NRC'FORM 366A (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION FACILITYNAME(1)

Cook Nuclear Plant Unit 1 DOCKET NUMBER(2) 50-315 YEAR 98 LER NUMBER (6)

SEQUENTIAL NUMBER 029 REVISION NUMBER 00 PAGE (3) 3of3 TEXT (ifmore space is required, use addliional copies ofNRC Form (366A) (17)

ANALYSISOF EVENT (cont'd)

The delay in determining the reportability of this condition is due largely to the scarcity of information pertaining to this design feature.

No documentation or calculation could be found to support the response time and air transit times reported in the response to Question 49.4 of the SAR. A preliminary determination originally concluded that the condition was not reportable because there was no commitment or surveillance to time damper travel. The reportability ultimately hinged on the results of the scoping calculation. The final determination of reportability was made when the results of the calculation were provided and proved to be less conservative than the value reported in response to Question C9.4 of the SAR.

CORRECTIVE ACTIONS

The spent fuel pool ventilation system was declared inoperable.

The analysis of record and UFSAR section(s) for fuel handling accidents in the Auxiliary Building willbe'updated so that no credit is taken for the charcoal absorption when determining off-site dose consequences.

Once the analysis is updated, a 10CFR50.59 Safety Evaluation successfully performed, and required surveillances completed, the ventilation system willbe declared operable.

Until that time the system willremain inoperable.

FAILEDCOMPONENT IDENTIFICATION Not Applicable

PREVIOUS SIMILAREVENTS

None-NRI FORM 366A (4-95)