ML17228A857
| ML17228A857 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 09/21/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17228A856 | List: |
| References | |
| TAC-M89906, NUDOCS 9409280165 | |
| Download: ML17228A857 (3) | |
Text
~44~ ~50II+
~o Cy A,
I O
IVl0 Cy
~O
++*++
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE RE UEST FOR RELIEF NO.
15 TAC NO.
M89906 DOCKET NO. 50-335 FLORIDA POWER AND LIGHT COMPANY ST.
LUCIE PLANT UNIT 1
- 1. 0 INTRODUCTION In a letter of July 15;
- 1994, as supplemented on August 4, 1994, Florida Power and Light Company (FPL), the licensee, submitted a request for relief from the required hydrostatic pressure test following the installation of a" replacement valve at St. Lucie Plant, Unit l.
In the original submittal (relief request 15), the licensee proposed an alternative consisting of Code Case N-416-1 with additional preservice nondestructive examinations (NDEs).
The NRC has not endorsed Code Case N-416-1.
In the supplement (relief request 15A), the licensee submitted additional and clarifying information in support of the original request and removed the reference to Code Case N-416-1 from the proposed alternative.
The licensee's submittal, as supplemented, contains sufficient information for the evaluation of the proposed alternative to the required hydrostatic test.
2.0 BACKGROUND
During the October 30, 1994, refueling outage, the licensee has scheduled the replacement of a 10-inch gate valve at St. Lucie Plant, Unit 1.
The valve, identification number V-3480, is located in the safety injection system between the reactor coolant system (RCS) and one of the safety injection cooling trains.
The valve is classified as an American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code Class 1 valve.
The approved ASME edition for the current second inspection interval at St. Lucie is the 1983 Edition, Summer 1983 Addenda.
3.
~ERE E
EN The examination requirements for valve V-3480 are specified in Table IWB-2500-1, Examination Category B-J, Item B9. 11, Surface and volumetric examination of the circumferential welds; Examination Category B-M-2, Item B12.50, Visual, VT-3 the internal surface; and Examination Category B-P, Items B15.51 and B15.71, system hydrostatic test of the valve and connecting piping.
4.0 RE VEST FOR RELIEF The licensee requested relief from the requirements specified in Table IWB-2500-1, Examination Category B-P, Items B15.51 and B15.71 following the replacement of valve V-3480.
94092EIOi65 940921
'DR ADOCK 05000335 P
'DR
5.0 BASIS FOR RELIEF The Code of Federal Regulations, 10 CFR 50.55a(a)(3)(ii),
allows for the use of proposed alternatives to Code requirements provided that the licensee demonstrates that compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
- 5. 1 Hardshi or Unusual Difficult To perform the hydrostatic pressure test, the licensee states:
It is not feasible to isolate the replacement valve and installation welds from the reactor pressure boundary.
In order to perform the hydrostatic pressure
- test, a freeze seal must be installed between valve V-3480 and the reactor coolant system loop A hot leg.
In the event of leakage, loss of this freeze seal during the test could cause loss of RCS inventory.
The performance of the required RCS hydrostatic pressure test would result in extending the outage schedule by as much as two days and increase the radiation dose to plant personnel by approximately 55 manrem.
5.2 Safet and ualit The licensee states that the safety and quality is assured as a result of the following:
A hydrostatic pressure test of valve V-3480 will'be conducted in the shop at a
pressure of 5675 psi.
The performance of a hydrostatic test at a pressure greater than the nominal system operating pressure is of little benefit with respect to assuring system integrity.
This has been recognized by the ASME Code committee through issuance of several ASME Code cases (examples:
N-416-0, N-498, and N-416-1).
The structural integrity of the replacement welds can best be assured by the conduct of NDEs (volumetric and surface examination methods).
6.0 PROPOSED ALTERNATIVE EXAMINATION The licensee proposed to conduct the following examinations and tests:
NDEs (radiography and surface) shall be performed in accordance with the methods and acceptance criteria of Subsection NB-5000 of the 1980 Edition through Winter 1980 Addenda of Section III.
Following the installation of replacement valve (V-3480) and prior to returning the shutdown cooling valve to service, the shutdown cooling return line would receive an inservice pressure test based on the nominal operating pressure of 257 to 267 psia and at a temperature less than 325'F.
Prior to or immediately upon returning the valve to normal operating service, a visual examination (VT-2) shall be performed in conjunction with a system leakage test, using the 1983 Edition through the Summer 1983 Addenda of Section XI, in accordance with IWA-5000 based on the nominal operating pressure of 2250 psia and temperature.
The system pressure testing hold times shall be 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated components and 10 minutes for uninsulated components.
Use of this relief request shall be documented on an NIS-2 form.
In addition to the NDE requirements of Section III, FPL will conduct preservice NDEs as required by the 1983 Edition through the Summer 1983 Addenda of Section XI of the ASME Code.
As required by the in-service test (pump and valve) program, FPL shall conduct preservice tests (leak rate and stroke) before placing the valve into service.
7.0 APPLICATION TIME PERIOD FOR RELIEF
'he licensee requested relief through the end of the inspection interval, February 10, 1998.
- 8. 0 EVALUATION The NRC has not endorsed Code Case N-416-1 and 1992 Edition of Section XI of the ASME Code that was referenced by the document.
The NRC staff reviewed the licensee's request for relief independently of Code Case N-416-1 and the 1992 Edition of Section XI of the ASME Code.
The licensee reports the difficulties in performing a hydrostatic test on valve V-3480.
The difficulties have been recognized in Code Case N-416 for Class 2 systems, which has been endorsed by the NRC in Regulatory Guide
- 1. 147, Revision 10.
The valve cannot be isolated from the reactor vessel pressure boundary.
In order to perform the required hydrostatic pressure test, the reactor vessel and a large portion of the reactor pressure'boundary would have to be pressurized or a freeze plug capable of withstanding 2295 psig for 10 minutes for uninsulated piping and 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated piping would have to be installed in the 10-inch pipe.
The licensee states that the performance of the test would extend the outage by two days and increase the radiation exposure to plant personnel by an estimated 55 manrems.
The valve's integrity is verified with a preinstallation hydrostatic pressure test conducted at a pressure of 5675 psi.
The proposed system leakage test is conducted at 2250 psia, which is only 2 percent below the required system hydrostatic test pressure of 2295 psia.
The small increase in pressure associated with the system hydrostatic test produces only a small increase in stresses.
By using the test pressures of a system leakage test, the hold times for a system hydrostatic test, and conducting a VT-2 visual examination, the system's leakage integrity is assured.
By using the NDE performed in accordance with the methods and acceptance criteria of the applicable subsections of Section III with the additional testing described
- above, the structural integrity of the welds is assured.