ML20195K148

Safety Evaluation Authorizing Relief Request RV-23A for Duration of Current 10 Yr IST Interval on Basis That Compliance with Code Requirements Would Result in Hardship Without Compensating Increase in Level of Quality & Safety

ML20195K148
Person / Time
Site:	Quad Cities
Issue date:	06/16/1999
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20195K146	List: ML20195K141 ML20195K148
References
NUDOCS 9906220010
Download: ML20195K148 (4)

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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30006 0001 o,k SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO INSERVICE TESTING PROGRAM RELIEF REQUEST FOR COMMONWEALTH EDISON COMPANY 8HQ MIDAMERICAN ENERGY COMPANY QUAD CITIES STATION UNITS 1 ANQ,2 DOCKET NUMBERS 50-254 AND 265 l

1.0 INTRODUCTION

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l The Code of FederalRegulations,10 CFR 50.55a, requires that inservics testing (IST) of J certain American Society of Mechanical Engineers (ASME) Code Class 1,2, and 3 pumps and valves are performed in accordance with Section XI of the ASME Boilerand Pressure Vessel ]

l Code (the Code) and applicable addenda, except where attematives have been authorized or )

relief has been requested by the licensee and granted by the Commission pursuant to Sections (a)(3)(i), (a)(3)(ii), or (f)(6)(i) of 10 CFR 50.55a. In proposing altematives or requesting relief, the licensee must demonstrate that: (1) the proposed altamatives provide an acceptable level of quality and safety; (2) compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety; or (3) conformance is impractical for its facility. Section 50.55a authorizes the Commission to approve attematives and to grant relief from ASME Code requirements upon making the necessary findings.

Guidance related to the development and implementation of IST programs is given in Generic Letter (GL) 89-04, " Guidance on Developing Acceptable Inservice Testing Programs," issued April 3,1989, and its Supplement 1 issued April 4,1995. Also see NUREG-1482, " Guidelines for Inservice Testing at Nuclear Power Plants," and NUREG/CR-6396, " Examples, Clarifications, and Guidance on Preparing Requests for Relief from Pump and Valve Inservice Testing Requirements."

The 1989 Edition of the ASME Code is the latest edition incorporated by reference in l Paragraph (b) of Section 50.55a. Subsection IWV of the 1989 Edition, which gives the  !

requirements for IST of valves, references Part 10 of the American National Standards institute /ASME Operations and Maintenance Standards (OM-10) as the rules for IST of valves.-

OM-10 replaces specific requirements in previous editions of Section XI, Subsection IWV, of the ASME Code. Subsection IWP of the 1989 Edition, which gives the requirements for IST of pumps, references Part 6 of the American National Standards institute /ASME Operations and Maintenance Standards (OM-6) as the rules for IST of pumps. OM-6 replaces specific requirements in previous editions of Section XI, Subsection lWP, of the ASME Code.

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9906220010 990616 '

PDR ADOCK 05000254 P PDR

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' The licensee's IST program covers the third 10-year IST interval for Quad Cities Station Units 1 and 2. By a letter dated April 9,1998, Commonwealth Edison Company (the licensee) submitted three relief requests (RV-02B, RV-038, and RV-23A) requesting relief from certain inservice testing requirements of ASME Code Section.XI. The staff reviewed the submittal and discussed the relief requests with the licensee on December 31,1998, and March 2,1999. As a result of the discussion with the NRC staff, the licensee reevaluated relief requests RV-02B and RV-038. ' Based on its review of industry practices and input from ASME Code experts, the licensee has determined that relief requests RV-02B and RV-03B are not required.

Accordingly, in a letter dated April 29,1999, the licensee withdrew these two relief requests.

The staff has completed its review of the remainhg relief request RV-23A and is providing the following evaluation.

2.0 VALVE RELIEF REQUEST RV-23A RV-23A applies to solenoid valves 2301-032-SO for both Unit 1 and Unit 2. The licensee requests relief from the stroke time test requirements of Paragraph 4.2.1 of OM Code, Part 10.

2.1 Licensee's Basis For The Relief Reauest The licensee states:

These valves are not equipped with position indication and the valves are totally enclosed, so valve position cannot be verified by direct observation. Therefore, it is impractical to exercise and stroke time these valves in accordance with Code requirements. Valve actuation may be indirectly verified by removing the HPCI system from service, filling the drain pot with water until the high level alarm is received, and observing that the high level alarm clears. It is impractical to assign a maximum limiting stroke time to these valves using this test method because the time for the alarm to clear would depend primarily on variables such as the rate of filling and the level of the drain pot when the filling is secured. The steam line drain pot is not equipped with direct level indication; therefore, the time required for the alarm to clear may vary significantly, Failure of these valves to perform their safety function would be indicated by a drain pot high level alarm during operation with low pressure steam. Additionally, ,

condensate entrapped in the steam would cause significant fluctuations in exhaust steam header pressure.

Compliance with the quarterly exercising and stroke timing requirements of the Code would require either system modifications to replace these valves with ones of testable design, or to purchase non-intrusive test equipment and develop new test methods and procedures. These altematives would be burdensome due to the costs involved.

m 2.2 Aftemate Testina The licensee states:

Stroke times will not be measured, and corrective actions based on stroke time will not be implemented.

Becauseixercising the subject valves without stroke timing provides no measure of valve degradation, a functional verification test is conducted on the drain pot level limit switches and the associated control room annunciators at least once every 90 days.

V.alve actuation will be. indirectly verified by removing the HPCI system from service and by filling the drain pot with water until the high level alarm is received. Positive draining of the HPCI drain pot will be indicated by a level increase in gland seal condenser and by the clearing of the high level alarm.

2.3 Evaluation These solenoid valves function as a backup to the exhaust line drain pot steam trap. During normal operation of the turbine using high quality steam, the drain path from the drain pot to the torus via the steam trap is adequate to remove condensate from the turbine exhaust line.

However, during turbine operation with low pressure and low quality steam (which is seen during HPCI surveillance testing during plant startup and as would be expected during HPCI operation during a small break LOCA), condensate collects in the drain pot faster than it can be drained through the trap. Under these conditions, solenoid valves 1(2)-230132 open automatically to drain to the gland seal condenser upon receipt of a signal from a drain pot level switch when the drain pot level reaches the high level alarm setpoint. A high level condition sounds an alarm in the control room.

- These valves are not equipped with position indication and the valves are totally enclosed, so valve position cannot be verified by direct observation. Therefore, it is not feasible to exercise and stroke time these valves in accordance with requirements of ASME OM Code, Paragraph 4.2.1.4(b). Compliance with the Code requirements would require either major system modifications, or to develop new test methods and procedures of using non-intrusive test equipment. -

- In lieu of the Code-required stroke time test, the licensee proposes a functional verification test using the drain pot level limit switches and the associated control room annunciators at least once every 90 days. Valve actuation and operability will be indirectly verified by the proposed test, i.e., by removing the HPCI system from service and by filling the drain pot with water until the high level alarm is received. Positive draining of the HPCI drain pot will also be indicated by a level increase in the gland seal condenser and by the clearing of the high level alarm.

Furthermore, failure of these valves to perform their safety function would also be indicated by a drain pot high level alarm during operation with low pressure steam. Additionally, condensate entrapped in the steam would be detected by significant fluctuations in exhaust steam header pressure. ,.

The staff finds that the proposed functional verification test and high water level alarms in the control room provide reasonable assurance of operational readiness of the affected valves, e _

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4 and compliance with the Code requirements would result in a hardship without a compensating increase in the level of quality and safety, it should be noted that in NUREG-1482 (page 4-15),

the staff discusses new diagnostic methods that have been developed to measure the stroke time or monitor the condition and degradation of SOVs. The licensee should review the industry practice and consider developing new diagnostic methods for use during the next 10 year IST interval. As such, pursuant to 10 CFR 50.55a(a)(3)(ii), the relief request RV-23A is authorized for the duration of the current 10-year IST interval.

3.0 CONCLUSION

Pursuant to10 CFR 50.55a(a)(3)(ii), the relief request RV-23A is authorized for the duration of the current 10 year IST interval on the basis that compliance with the Code requirements would result in a hardship without a compensating increase in the level of quality and safety. ,

Principal Contributor: J. Huang Dated: June 16, 1999 l

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