ML20077F177
| ML20077F177 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 12/06/1994 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ULNRC-3110, NUDOCS 9412130294 | |
| Download: ML20077F177 (4) | |
Text
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1901 Chouteau Avenue Post Office Box 149 St. Louis, Mssaun 63166 l'
31& 554 2650 f -
U-NION Donald F. Schnell Etscrusc sen,o, wce r,es:sent u-13 December 6, 1994 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Mail Station P1-137 Washington, D.C. 20555 ULNRC-3110 Gentlemen:
DOCKET NUMBER 50-483 CALLAWAY PLANT ASLDLCQ_D_5 CASS_N-4 9 8 -1
Reference:
ULNRC-3042 dated July 8, 1994 The referenced letter requested NRC approval of ASME Code Case N-498-1 for use at Callaway Plant.
The following information supplements ULNRC-3042, and is provided at the request of the NRC.
Code Case N-498-0 provides for exemption of ASME Class 1 and Class 2-systems from the 10 year ISI hydrostatic testing requirements of Section XI of the ASME Code.
This Code Case has been endorsed by the NRC, and is currently listed in Regulatory Guide 1.147.
NRC approval of N-498-0 indicates NRC concurrence with several of the precepts which form the bases for N-498-0, including:
Hydrostatic testing' subjects piping and components to a pressure only slightly above design pressure.
This smali increase in pressure does not present a meaningful test of structural integrity.
Due to the relatively low pressures used, hydrostatic testing serves primarily as a means of leakage detection.
Industry experience has shown that leakage is more likely to be detected during normal system operation than during a hydrostatic test.
Most leaks are detected while the system is at normal operating pressure.
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U.S. Nuclear Regulatory Commission Page 2 10-year ISI hydrostatic tests are performed e
only once each 10-year interval.
System leakage tests at nominal operating pressure are conducted a minimum of once each refueling cycle for Class 1 systems, and once each 40 month period for Class 2 and Class 3 systems.
Hydrostatic testing imposes significant hardships on Owners, due the efforts required to set up and perform the tests.
Hydrostatic testing imposes considerable costs on Owners (including increases in critical path activities) without a commensurate increase in plant safety.
Revision 1 to Code Case N-498 exempts ASME Class 3 systems from 10-year ISI hydrostatic tests, in addition to maintaining the currently approved exemptions for ASME Class 1 a,d 2 systems.
The philosophy which formed the basis for approval of N-498-0 is equally applicable to N-498-1.
Cost impacts associated with ASME Class 3 systems are frequently significant, while hydrostatic tests on these systems do not provide a meaningful contribution to plant safety.
As examples of these increased costs, 65 ASME Class 3 ISI hydrostatic tests are required at the Callaway Plant each 10-year interval.
The cost of these tests is conservatively estimated at $253,760.00 per interval.
This estimate does not include costs associated with potential increases in refueling outage work scope, nor does it consider potential increased outage critical path.
Fifty-two of the 65 Class 3 hydrostatic tests are complete.
The remaining thirteen are required to be completed during Callawai's seventh refueling outage, which is scheduled to begin in March, 1995.
Ten of these thirteen affect Callaway's Diesel Generator oil systems.
All ten of these Diesel Generator hydrostatic tests will decrease Diesel Generator availability during the refueling outage.
This potential safety redu : tion alone is considered sufficient to offset any perceived safety increase resulting from hydrostatic testing; however, five of these ten hydrostatic tests will also increase outage critical path.
The result is a considerable hardship without a commensurate safety increase.
The three remaining hydrostatic tests apply to Component Cooling Wate systems.
While all three will increase component unavailability, one involves the "A" RHR pump and hee.t exchanger.
Performance of
'O U.S. Nuclear Regulatory Commission Page 3 this hydrostatic test will increase safety system unavailability, with a corresponding decrease in plant shutdown safety.
Pursuant to 10CFR50.55 (a) (3), approval for use of Code Case N-498-1 at the Callaway Station is hereby requested.
If you have any questions concerning this letter, please contact us.
Very truly yours, trou Donald F.
Schnell
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cc:
T. A.
Baxter, Esq.
i Shaw, Pittman, Potts & Trowbridge 2300-N. Street, N.W.
Washington, D.C.
20037 M. H.
Fletcher Professional Nuclear Consulting, Inc.
18225-A Flower Hill Way i
Gaithersburg, MD 20879-5334 l
L. Robert'Greger Chief, Reactor Project Branch 1 U.S. Nuclear Regulatory Commission Region III 801 Warrenville Road i
Lisle, IL 60532-4351 Bruce Bartlett
-Callaway Resident Office' U.S.
Regulatory Commission RR#1 Steedman, MO 65077 L. R. Wharton (2)
Office of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Commission 1 White Flint, North, Mail Stop 13E21 11555 Rockville Pike Rockville, MD 20852 Manager, Electric Department Missouri Public Service Commission P.O.
Box 360 Jefferson City, MO 65102
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