ML19338E078

Significant Deficiency Rept SD 369/80-15:on 800917, Pressurizer Cavity Exceeded Design Temp.Caused by Insufficient Ventilation Cooling Flow & Higher than Design Heat Loads.Permanent Temp Monitoring Sys Will Be Installed

ML19338E078
Person / Time
Site:	McGuire
Issue date:	09/18/1980
From:	Donat T DUKE POWER CO.
To:
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8009240481
Download: ML19338E078 (4)

Text

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DUKE POWER COMPANY Powra Duit.ntxo

.we Sourn Cuencu Srnrer. Cuant.orre. N. C. ena42 wn.uw o. aa na cn. s n. September 18, 1980 A;r PattaDC'et S.gan. Pacouctrog I=

C E *M O N C. A m t A 704 373 4083 Mr. James P. O'Reilly, Director U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 Re: McGuire Nuclear Station Unit 1 Docket No. 50-369

Dear Mr. O'Reilly:

Pursuant SD 3f9/80-15. to 10CFR 50.55e please find attached Significant Deficiency Report

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Ve y truly yours,j',

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, N .. Ib. c w { &

'-- ' William O. '

Parker, Jr.l -)

LJB:ses cc: Director Office of Inspection & Enforcement Mr. Tom Donat, NRC Inspector U. S. Nuclear Regulatory Commission McGuire Nuclear Station Washington, D. C. 20555 So/9 s

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DUKE POWER COMPANY MCGUIRE NUCLEAR STATION Report Number: SD-369/80-15 Report Date: September 17, 1980 O

Facility: McGuire Nuclear Station, Unit 1 Identification cf Deficiency: Pressuricer Cavity Exceeded Design Temperature Description of Deficiency:

On August 19, 1980 W. H. Bradley and J. K. Berry advised Mr. Don Price, NRC/0IE, that during Unit 1 hot functional testing, the pressurizer compartment tenperature exceeded the design temperature of 120oF. This abnormally high temperature con-dition existed from approximately July 1, 1980 to July 17, 1980. The pressurizer compartment temperature is estimated to have reached 2500F during this period.

The abnormally high temperature was due to insufficient ventilation cooling flow and higher than design heat loads as a result of having removed several pieces of compartment piping insulation to record piping thermal growth measurements.

As a result of being exposed to sustained high temperature, some components located inside the compartment were damaged or the associated environmental qualification life compromised. The damaged equipment included hydraulic snubber reservoirs, valve electric motor operators and nylon electric cable ties.

Analysis of Safety Implications:

Assuming the following scenario the worse case implication of a postulated failure of the af fected safety-related equipment could result in some loss of reactor coolant.

1) Systems to lift.

transient (s) causes pressurizer power operated relief valve (PORV)

2) Single failure of pressurizer PORV causing it to remain open.  ;

3) Pressurizer PORV block valve electric motor operator (EMO) failes to operate l leaving a reactor coolant leak path open. The failure of the valve EMO is '

postulated to be due to a significant reduction in the qualified life of the EMO due to the high hot functional testing temperature in the pressurizer compartment : d occurrance of a postulated transient after the qualified life was exceeded.  !

Corrective Actiot.:

1 During subsequeat hot functional testing the pressurizer compartment operating temperature was reduced belcw the 1200F design value by a combination of the follcwing; replacing the removed insulation, adding additional insulation and increasing ventilation cooling air flow to the compartment, j

, 4 Corrective Action (Continued)

A permanent compartment temperature monitoring system has been designed and will be installed by October 3, 1980 to preclude similar situations.

Safety related components located inside the pressurizer compartment were evaluated to' determine the effects of high temperature. The following actions were taken:

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1) Electrical Cable The effect on electrical cable was evaluated and it was determined that no cable replacement is required.

2) Cable' Ties I

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The high temperature caused embrittlement of some nylon cable ties within cable trays. Metal cable ties have been installed in lieu of nylon ties where cable support is required, a

3) Pressurizer Safety Relief Valve Acoustic Leak Monitoring Equipment i

This equipment was evaluated and rather than expend effort to determine the finite remaining qualified life, the convertors were replaced. '

Installation of new solid state convertors is complete.

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4) Pressurizer Power Operated Relief Valve (PORV) Stem Mounted Limit Switches '

l Stes' mounted limit switches were replaced on pressurizer PORV's INC32B, INC34A and INC36B.

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5) Pressurizer PORV Block Valves The electric motor operators (EMO) on valves INC33A and 1NC35B were damaged 1

as a result of the high temperature. EM0's on PORV block valves INC31B, INC33A and 1NC35B were replaced, i

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6) Solenoid Valves i Solenoid valves were evaluated with respect to high temperature effects.

Six solenoi.1 valves, INCSV0320, INCSV0321, INCSV0340, INCSV0341, INCSV0360, 4

i 1NCSV0361,will be replaced by October 27, 1980.

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7) Hydraulic Snubbers .

4 All hydraulic snubbers were evaluated with respect to high temperature

' effects. The inspection revealed that six of the thirty-five snubber plastic reservoirs had yielded due to the high temperature.

Twenty-four, NC-671, 672, 673. 676, 682, 683, 684, 751, 759, 760, 795, 678, 6SS, 686, 689, 762, 763, 765, 767, 768, 750, 770, 766, and 773, of the hydraulic snubbers were replaced with mechanical snubbers. On the remaining eleven hydraulic snubbers, NC-687, 679, 769, 674, 753, 754, 756, 784, 677, 670, and 669, local plastic reservoirs were replaced with remote stainless steel metal reser! trs.

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8) Structural Evaluation The reinforced concrete pressurizer compartment was investigated to determine the structural effects of the high thermal gradient across the enclosure. The results of this investigation revealed no adverse structural effects of the reinforced concrete enclosure. In addition, the enclosure was physically inspected by a team of qualified structural e etneers. This inspection revealed no visable signs of cracking or

_. rete degradation.

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