05000255/LER-1994-010, :on 940302,two Hinged Horizontal Panels of Insulation Comprising Convection Barrier Not in Closed Position.Caused by Increase in Temp & Shallowness of Through Wall Gradients

:on 940302,two Hinged Horizontal Panels of Insulation Comprising Convection Barrier Not in Closed Position.Caused by Increase in Temp & Shallowness of Through Wall Gradients

ML18059A992
Person / Time
Site:	Palisades
Issue date:	05/11/1994
From:	Rogers D, Smedley R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-94-010, LER-94-10, NUDOCS 9405170146
Download: ML18059A992 (3)

LER-1994-010, on 940302,two Hinged Horizontal Panels of Insulation Comprising Convection Barrier Not in Closed Position.Caused by Increase in Temp & Shallowness of Through Wall Gradients

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ii)
2551994010R00 - NRC Website

text

consumers Power POW ERi Nii MICHlliAN"S. PROGRESS Palisades Nuclear Plant:

27780 Blue Star Memorial Highway, Covert, Ml 49043 May 11, 1994 Nuclear Regulatory Commission ATTN:

Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -

David W. Rogers Plant Safety and Licensing Director LICENSEE EVENT_ REPORT 94.-010 - OPEN CONVECTION BARRIER PANELS RESULT IN BIOSHIELD CONCRETE TEMPERATURES IN.EXCESS OF TECHNICAL SPECIFICATION LIMIT.

Licensee Event Report (LER)94-010 is attached. This event is reportable in acco~dance with 10CFR50.73 (a)(2)(ii)(B) as a condition outside the design basis of the plant.

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,David W. Rogers Plant Safety and Licensing Director CC Administrator; Region III, USNRC NRC Resident Inspector - Palisades Attachment 9405170146 940511 PDR ADOCK 05000255 S

PDR A CMS ENERGY COMPANY

I

,l NRC Form 388 U.S. NUCLEAR REGULATORY COMMISSION (9-83)

APPROVED OM8 NO. 3160--0104 EXPIRES: 8/31 /86 LICENSEE EVENT REPORT (LER)

FACILITY NAME (1)

DOCKET NUMBER 121 PAGE (3)

Palisades Plant olslol0Jol2lsl 5 1 I OF 0 12 TITLE 14> OPEN CONVECTION BARRIER PANELS RESULT IN BIOSHIELD CONCRETE TEMPERATURES IN EXCESS OF TECHNICAL SPECIFICATION LIMIT.

EVENT DATE (6)

LER NUMBER (8)

REPORT DATE 18)

OTHER FACILITIES INVOLVED (8)

SEQUENTIAL 1

• REVISION FACILITY NAMES MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR N/A o I 6 I o I o I o I I 0 13 012 9

4 914 o

I 1 Io o lo ols 1 I 1 914 N/A ol61ololol I

THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR I: fCh<<:lc OM ortnan1 of rho following} 111 l OPERATING N

MODE 19) 20.4021b) 20.406(c) 60.73(a)(2)(iv) 73.7l(b) 73.7i(c)

POWER 20.4061aH1 >m 60.38lcH1l 60.731aH2lM LEVEL

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20.4061aH1 Hiiil 60.73laH2Hil 60.7 31aH2Hviii)(A) below and in Text, 20.406(a)(1 )(iv) x 60.731aH2Hii) 60.731*H2Hviii)(B),

NRC Form 386A) 20.406(a)(1 )(v) 60.73(a)(2)(iii) 60.73(e)(2)(x)

LICENSEE CONTACT FOR THIS LER 1121 NAME TELEPHONE NUMBER Richard W. Sm!i!dley, Staff licensing Engineer AREA CODE I sl 1 Is 11sl41 -I s I 9 I 1 I 3 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

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SYSTEM COMPONENT TURER TO NPRDS

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I SUPPLEMENTAL REPORT EXPECTED 1141 MONTH DAY YEAR rxi NO EXPECTED n YES Uf,yea, complete EXPECTED SUBMISSION DA TEI SUBMISSION I

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DATE (161 ABSTRACT UJmft to 1400 -*** I.e., epproximllto/y fifteen aingl,,.-* typewritten lineal (16)

On March 2, 1994, with the plant in cold shutdown, it was verified that two of the hinged horizontal panels of insulation comprising the convection barrier around the reactor vessel were not in the closed position. later, on April 12, 1994, with the plant still in cold.shutdown, it was determined that the two open sections of the barrier allowed the concrete bioshield temperature to increase above limits established in the Technical Specifications.

Although the Technical Specification design limit for the concrete of 165

• F was exceeded, the bioshield was effected only where the reactor vessel insulation was open.

Preliminary analysis indicates that the bioshield wall remained operable. The lack of adverse impact to the bioshield was attributed to the loc,al nature of the temperature increase, the shallowness of the through wall gradients, the relatively low magnitude of the applied loads and the distribution of those loads. Both open sections of the barrier were closed cm March 1 3, 1994. The final analysis *of the impact of the openings in the convection shield on the bioshield itself will be completed before plant startup from the current maintenance outage.

,I

~RC Form 366A 18-831 FACILITY NAME 111 Palisades Plant

Event Description

LICENSEE EVENT REPORT (LERI TEXT CONTINUATION DOCKET NUMBER 121 YEAR

• LER NUMBER.131 SEQUENTIAL NUMBER U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 315~104 EXPIRES: B/31/85 REVISION NUMBER.

PAGE 141 0500025594-0 0

0 0

0 2

OF 0

2 On March 2, 1994, with the plant in cold shutdown, it was verified that two of the hinged horizontal panels of insulation in the convection barrier around the reactor vessel were not in the closed position. On April 12, 1994, with the plant in cold shutdown, analysis of data regarding open insulation indicated that the maximum allowed temperature of the concrete bioshield was exceeded by 25

• F to 65

• F. Palisades Technical Specification (TS) 3. 1 5 notes that the shield cooling system is required to be operable to maintain the temperature of concrete surrounding the reactor cavity below 165

• F. Both of the insulating panels were put back in place on March 13, 1994.

On November 7, 1988, it was identified that two of the convection barrier insulation panels were open. Reviews at that time, based on temperature readings in the upper region of the cavity, indicated that there was no significant effect on concrete temperatures with the two panels open. A work order had been initiated in 1992 to put the panels in the closed position during the 1993 refueling outage but was deferred because of the workload and ALARA concerns.

On March 3, 1993, a thermal analysis was performed and a shield wall temperature profile was developed. The analysis concluded that the insulation panels were needed to maintain the concrete temperature level below 1 6 5

• F.

ANALYSIS OF EVENT

Technical Specification 3.15 notes that the reactor shield cooling system *is in place to maintain th~ temperature of the concrete bioshield below 165

• F. A preliminary analysis of the effect of having two of.the insulation panels open. showed the impact, if any, would occur above the 600-foot elevation where the insulating panels are installed. The analysis also indicated that the temperature of the concrete surface and internal temperatures exceeded the 165

• F maximum when the insulation panels were not closed. This is reportable per 10CFR50.73 (a)(2)(ii)(BJ as a condition that was outside the design basis of the plant.

SAFETY SIGNIFICANCE AND OPERABILITY The reactor Shield Cooling System is designed to remove heat from the biological shield surrounding the reactor to limit any thermal stresses in the structural concrete. The insulation was installed as a convection barrier to prevent hot air in the lower region of the reactor from impacting the uninsulated shield wall above the barrier. Analyses performed since discovery of this condition indicates tha't a localized *increase in concrete temperature (above the open insulation) could occur and would diminish within the wall. Earlier studies of the impact of higher temperatures, in the 200

• F to 250

• F range, indicate that there would be no significant impact on the ability of the bioshield wall to perform its safety function because* there would be no adverse affect o the concrete itself. Therefore, based on preliminary analysis, the 200

• F to 230 ~ F localized temperatures caused by the open panels had no effect on the safety margin or the operability of the bioshield wall.

CORRECTIVE ACTIONS

• Plant pers,onnel put both insulation panels back in position March 13, 1994. The plant will complete a final th.ermal analysis of the biological shield wall. as result of this event to verify operability. The analysis will be completed prior to plant startup from the current outage. Also, an evaluation of the work order extension process will be completed by July 15, 1994 which is directed at the potential problem of missing an opportunity to correct an irlentified problem in a timely fashion.

PREVIOUS OCCURRENCES

None: