ML20003E011

Responds to IE Bulletin 80-25, Operating Problems W/Target Rock Safety Relief Valves at Bwrs. Facility in Process of Revising Corrective Maint Procedures.Detailed Response to Applicable Questions Encl

ML20003E011
Person / Time
Site:	Zimmer
Issue date:	03/17/1981
From:	Borgmann E CINCINNATI GAS & ELECTRIC CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-80-25, NUDOCS 8104020052
Download: ML20003E011 (7)

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THE CINCINNATI GAS & ELECTRIC COMPANY CINCIN N ATt OHIO 4 5201 March 17, 1981 L A. BORGMANN stN'on v CE amtsectNT U.S. Nuclear Regulatory Commission ( N Region III 799 Roosevelt Road q. g O.

Glen Ellyn, Illinois 60137 i d Attention: Mr. James G. Keppler,

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Regional Director >  %

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RE: WM. H. ZIMMER NUCLEAR POWER STA (O IE BULLETIN 80-25, DOCKET 50-358,1#,E G PROBLEMS WITF TARGE;T ROCK SAFETY RELIEF VALVES W.O. 57300, JOB E-5590, FILE IE-3 RING Gentlemen:

This is in response to the above referenced IE Bulletin concerning Operating Problems with Target Rock Safety F.elief Valves.

An investigation was initiated to determine the applicability of this Bulletin to the Zimmer Station. In this investigation, the test procedures and acceptance criteria were examined for our safety relief valves and actuator assemblies.

Also, methods of detecting and correcting Safety Relief Valve malfunctions were evaluated. In addition, the drywell pneumatic system was evaluated to determine if it meets the criteria specified in this Bulletin.

Zimmer Station Unit 1 is equipped with Crosby Valve and Gage Co. Safety Relief Valves and actuator assemblies.

Recently, these valve's have undergone an extensive retrofitting program to install a new flexible disc design which greatly reduces seat leakage, and to install a redesigned Pneumatic Actuator Assembly to increase reliability of the SRV in the relief mode of operation. With the recent improvement in the design of these valves, we expect operating problems to be minimized.

The Cincinnati Gas & Electric Company is in the process of revising corrective maintenance procedures to assure that malfunctioning SRV's are dispositioned in accordance with this Bulletin. Also, we have initiated cn Engineering Change Request to provide annunciation to the control room when a high or low l pressure condition exists in the drywell pneumatic supply system. l Operating procedures will be developed for high or low pressure conditions in the drywell pneumatic supply system. For a detailed response to applicable questions in this Bulletin, please refer to Attachment 1.

%AR 2 3199; s104ou o O'5 2 -

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To: U.S. Nuclear Regulatory Commission March 17, 1981 o

Re: Wm. H. Zimmer Nuclear Power Station Page #2 Unit 1 - IE Bulletin 80-25, Docket 50-358, Operating Problems with Target Rock Safety Relief Valves, W.O. 57300, Job E-5590, File IE-3 Ring We believe this response meets your requirements, therefore this item is considered closed.

Approximately sixty (60) man-hours have been expended in the review and preparation of this response.

Very truly yours, THE CINCINNATI GAS & ELECTRIC COMPANY By i , -f M f/ d}~ "f r ' d '^

E. A. Borgmann~~

RWR:bt Attachment cc: NRC Office of Inspection and Enforcement Division of Reactor Construction Inspection Washington, D.C. 20555 NRC Resident Inspector Attn: Mr. F. T. Daniels Sargent & Lundy Attn: Mr. R. F. Scheibel W. W. Schwiers J. D. Flynn S. G. Salay J. R. Schott H. C. Brinkmann W. D. Waymire State of Ohio )

County of Hamilton)ss Sworntoandgbscribedbeforeme this /7 day of March, 1981.

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Notary Public  !

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l ATTACHMENT 1  ;

Requested Action: In the event that a S/R valve, regardless of make or model (e.g. , both two or three stage) , fails to function as designed, excepting for pressure setpoint requirements, and the cause of the malfunction is not clearly determined, understood, and therefore corrected, standard operating procedures shall require that the entire valve be removed from service, disassembled, inspected, adjusted, and pressure setpoint tested with steam for proper operation prior to returning the valve to service. These overhaul requirements shall be at least equivalent to those applicable to periodic surveillance rehabilitation requirements. Appropriate revisions to your operating procedures shall be made to include these requirements.

Response: A malfunctioning Crosby SRV will be detected by operating personnel, who will initiate a work request'to correct the problem. Maintenance personnel will perform corrective maintenance in accordance with plant Corrective Maintenance Procedure ME. CMP.3.35.

A statement will be inserted in the precautions and limitations section, and one in the acceptance criteria as follows:

3.4 In the event that a S/R valve has failed to function as designed, excepting for pressure setpoint requirements, and the cause of the malfunction is not clearly determined, understood, and therefore corrected, remove the valve from service, disassemble, inspect, adjust, and test pressure setpoint prior to returning valve to service (IEB 80-25) .

6.4 In the event that this S/R valve was being worked on due to a failure to function as designed, excepting for pressure setpoint requirements, and the cause of the malfunction was not clearly determined, understood and corrected, ensure valve was disassembled, inspected, adjusted, and has'its pressure setpoint tested before returning valve to service (IEB 80-25) .

The insertion of these statements will assure compliance to  !

this Bulletin.

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l o Requested Action: A review of your S/R valve pneumatic supply i systems shall be performed to determine the potential fo:

and magnitude of an overpressure condition. The determined overpressure potential of the pneumatic supply shall be compared with the maximum operating pressure capabilities of the solenoid actuator valves serving the S/R valves, sc as to determine whether supply pressure could result in valve malfunction. Protective devices (such as relief valves) shall be installed in the proximity of the S/R valves and set to protect against supply pressure in excess of the operating pressure capabilities of the solenoid actuator device. In addition, consideration should be given to modification or replacement to reduce the sensitivity of the solenoid actuator to pneumatic supply overpressure. Further, the failure, either high or low, of the pneumatic supply system shall be annunciated to the control room operator. The annunciated supply pressure should be measured at a location as close as practical to the S/R valves and downstream of any check valve connecting two or more pneumatic sources. Appropriate operating procedures shall be provided to guide operator response to such an occurrence of high or low supply pressure.

Response: The Zimmer Main Steam Relief System consists of thirteen (13) air actuated Crosby Safety Relief Valves. Six (6) of these valves are included in the Automatic Depressurization System (ADS). See attached drawings M-40 Sheets 1,2 for the Drywell Pneumatic System. 'All SRV actuators receive supply air from the drywell pneumatic air system, which has a maximum operating pressure of 100 PSIG, design pressure is 230 PSIG, relief valves are set at 175 PSIG upstream of the control valve, and 125 PSIG downstream of the control valve, low pressure alarm setting is 90 PSIG. The low pressure alarm is sensed on the drywell pneumatic supply outside containment. A control valve set at 100 PSIG regulates pressure to the SRV actuators.

The six (6) ADS SRV actuators receive a backup supply from the drywell pneumatic nitrogen cylinders. This backup supply has a maximum operating pressure of 175 PSIG, a design pressure of 250 PSIG, relief valve setting is 250 PSIG, low pressure alarm setting on each SRV Accumulator is 145 PSIG. Each nitrogen bank is equipped with an alarm with a low pressure setpoint of 500 PSIG, sensed on the nitrogen system header outside centainment. A control valve set at 150 PSIG regulates pressure to the ADS SRV actuators.

All twenty (20) of the Zimmer SRV's (12 installed, 7 spares) are designed and tested to the same criteria. A review i of Crosby procedure MPP-4400 enabled us to find the following criteria on the SRV's and their actuator assemblies:

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The Pneumatic Actuator assemblies are designed for a pressure of 250 PSIG and a temperature of 350 deg. F.

Each actuator assembly is subjected to an aerostatic test at 313+ 2 PSIG for five minutes in both the fully open and fully closed positions. Each actuator is subjected to a leak test in both the fully open and fully closed positions. Thepressure for this test is 200+ 2 PSIG in the closed position and 313@ 2 PSIG in the fully open position. The test duration is five (5) minutes in each position after full pressure is reached. Total actuator system leakage cannot exceed 0.100 scfh.

Each solenoid valve is leak tested in the closed (de-energized) position by individually pressurizing each inlet port to 200 +0 PSIG for a duration of ten (10) minutes.

-5 Individual solenoid valve leakage cannot exceed 0.02 scfh.

Conclusions:

The ADS valves have adequate annunciation to the control room if a low pressure condition exists in the drywell pneumatic supply. The Crosby SRV actuator assemblies are designed to the pneumatic supply system design conditions.

The leak rate criteria for each solenoid (0.02 scfh) is much less than that of the actuator (0.100 scfh), there-fore, it is our judgment that a leak through the solenoids will not inadvertently actuate the SRV. Failure of a pressure control valve could result in a higher than normal pressure, however, the design value of the actuator assembly would not be exceeded.

The pneumatic supply to the ADS and Non-ADS valves will be annunciated to the control room when a high or low pressure condition exists. The pressure will be measured downstream of the source header check valves on each system. It is

our opinion that the existing relief valves, one located on the air receiver, set at 175 PSIG, the second located downstream of the control valve on the Non-ADS system, set at 125 PSIG, the third located on the pneumatic system supply just downstream of the nitrogen system control valve, set at 250 PSIG, provide adequate system overpressure protection.

Operator procedures will be developed for high or low

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pressure conditions on the drywell pneumatic system.

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