RS-03-182, Withdrawal of Inservice Testing Program Relief Request
| ML032671080 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/15/2003 |
| From: | Simpson P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RS-03-182 | |
| Download: ML032671080 (2) | |
Text
Exeons.
Exelon Generation www.exeloncorp.com Nuclear 4300 Winfield Road Warrenville, IL 60555 RS-03-182 September 15, 2003 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249
Subject:
Withdrawal of Inservice Testing Program Relief Request
References:
(1)
Letter from R. J. Hovey (Exelon Generation Company, LLC) to U. S.
NRC, "Submittal of Proposed Alternatives and Reliefs to the Requirements of 10 CFR 50.55a Concerning the Fourth Ten-Year Interval Inservice Testing Program," dated April 30, 2003 (2)
Letter from P. R. Simpson (Exelon Generation Company, LLC) to U. S.
NRC, "Additional Information Regarding Inservice Testing Program Relief Requests," dated August 6, 2003 In Reference 1, Exelon Generation Company, LLC (EGC) proposed various code alternatives and reliefs associated with the fourth ten-year inservice testing (IST) program for Dresden Nuclear Power Station, Units 2 and 3. In a teleconference between Mr. L. W. Rossbach and other members of the NRC and Mr. A. R. Haeger and other members of EGC on August 12, 2003, the need for one of the relief requests, RV-02A, was discussed.
Request RV-02A proposed relief from the American Society of Mechanical Engineers (ASME)
Operation and Maintenance (OM) Code, 1998 Edition through 2000 Addenda, Paragraph ISTC-5114(b), concerning stroke timing of the main steam relief and safety/relief valves. Due to the lack of positive valve open indication, these valves are stroke timed using indirect indication of valve opening. Because of this design feature and the typically short stroke times for these valves, EGC requested relief to indirectly stroke time these valves and adopt a 3.5 second limiting stroke time, to account for variations in operator reaction time in measuring the stroke time.
In the August 12, 2003, teleconference the NRC pointed out that the measured stroke times of these valves at DNPS, including operator reaction times, historically have not exceeded values that, with rounding, do not exceed two seconds. The NRC stated that these measured stroke times are consistent with the requirements of Paragraph ISTC-5114(c), which specifies that valves with stroke times less than two seconds may be exempt from Paragraph ISTC-5114(b) and in such cases shall have a limiting stroke time of two seconds. The NRC stated that since the historical stroke times, which include operator reaction have been within the code requirements, the NRC would be reluctant to approve less restrictive stroke times.
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1V September 15, 2003 U. S. Nuclear Regulatory Commission Page 2 EGC responded that since the main steam relief and safety/relief valves historical stroke times, including operator reaction time, are sometimes slightly greater than two seconds, a two-second limiting stroke time might be overly conservative and require corrective actions in situations for which no valve degradation exists.
Also, during the teleconference, EGC noted that DNPS refurbishes or partially refurbishes the main steam relief and safety/relief valves during each refueling outage. In accordance with the ASME OM Code, Paragraph ISTC-3310, reference stroke time values are to be re-established or the previous values confirmed following valve replacement, repair, or maintenance.
Deviations from previous reference values are to be analyzed and determined acceptable.
Thus, the reference stroke times for the main steam relief and safety/relief valves at DNPS may vary during each refueling outage, but will be controlled in accordance with the ASME Code within the DNPS IST program.
Considering the above information, EGC has determined that its current practices for stroke timing of the main steam relief and safety/relief valves are in accordance with the ASME OM code and that no relief is required. Thus, EGC has decided to withdraw relief request RV-02A.
In Reference 2, EGC supplied additional information regarding relief request RV-02A. This information stated, in part, that Limerick Generating Station (LGS) had proposed a 3.5-second limiting stroke time in correspondence with the NRC. Upon further review, we have determined this statement to be in error since the LGS correspondence referenced did not propose a specific limiting stroke time.
Should you have any questions concerning this letter, please contact Mr. Allan R. Haeger at (630) 657-2807.
Respectfully, Patrick R. Simpson Manager, Licensing cc:
Regional Administrator - NRC Region IlIl NRC Senior Resident Inspector - Dresden Nuclear Power Station Office of Nuclear Facility Safety - Illinois Department of Nuclear Safety