ML083170371
| ML083170371 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/12/2008 |
| From: | Calvert Cliffs |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| Download: ML083170371 (4) | |
Text
ATTACHMENT (1)
ALTERNATIVE PRESSURE BOUNDARY REQUIREMENTS DURING CLASS 1 SYSTEM PRESSURE TESTS, REQUEST FOR ALTERNATIVE RELIEF REQUEST PT-3-01 Calvert Cliffs Nuclear Power Plant, Inc.
November 12, 2008
ATTACHMENT (1)
ALTERNATIVE PRESSURE BOUNDARY REQUIREMENTS DURING CLASS 1 SYSTEM PRESSURE TESTS, REQUEST FOR ALTERNATIVE RELIEF REQUEST PT-3-01 American Society of Mechanical Engineers (ASME) Code Component(s) Affected The affected component is the Calvert Cliffs Nuclear Power Plant (Calvert Cliffs) Units 1 and 2 Class 1 pressure boundary extending beyond the first normally closed valve to the second boundary component.
Specifically, this request relates to Examination Category B-P and Item Numbers B15.50 (Piping) and B15.70 (Valves) from Table IWB-2500-1 and Subparagraph IWB-5222(b) of the ASME Boiler and Pressure Vessel Code (Code)Section XI.
Applicable Code Edition and Addenda
American Society of Mechanical Engineers Code,Section XI, Rules and Inservice Inspection of Nuclear Power Plant Components, 1998 Edition (no Addenda).
Applicable Code Requirement
American Society of Mechanical Engineers Code,Section XI, Subparagraph IWB-5222(b) boundaries states, The pressure retaining boundary during the system leakage test conducted at or near the end of each inspection interval shall extend to all Class 1 pressure retaining components within the system boundary.
Relief is requested from the specific ASME Code,Section XI, Subparagraph IWB-5222(b) requirement to extend the pressure boundary to all Class 1 pressure retaining components during the system leakage tests conducted at or near the end of the inspection interval.
Reason for Request
Pursuant to the provisions of 10 CFR 50.55a(a)(3)(ii), Calvert Cliffs requests approval to perform the examination of select Class 1 piping and valves at plant conditions other than those required by the ASME Code. Specifically, Calvert Cliffs proposes to conduct this required system leakage examination of the Class 1 pressure retaining components with the first normally closed or "inboard" isolation valves in their normally closed positions.
Relief is requested in accordance with 10 CFR 50.55a(a)(3)(ii) on the basis that hardship and unusual difficulty exists in establishing a system configuration that will subject all Class 1 pressure boundary components to Reactor Coolant System (RCS) pressure during the system pressure test without a compensating increase in the level of quality and safety. Extending the pressure retaining boundary during the system pressure test to all Class 1 pressure retaining components beyond the first normally closed valve, will require a number of off-normal temporary system configurations that includes, in some locations, the use of temporary piping installations, such as hard-pipe jumpers, and test pumps in order to achieve test pressures at system segments beyond the first isolation valve. Since the Class 1 system pressure testing is performed in Mode 3, these temporary configurations would conflict with Technical Specification requirements. In addition, establishment of and restoration from such temporary configurations will take a considerable amount of time, result in an unwarranted increase in worker radiation exposure, and will contribute to the risk of delaying normal plant startup following the refueling outage.
Based on the above reasons, extension of the boundary subjected to RCS pressure during this system leakage test at the end of the inspection interval to include all Class 1 pressure retaining components within the system boundary represents a hardship and unusual difficulty that does not provide a compensating increase in the level of quality and safety provided by the examination.
1
ATTACHMENT (1)
ALTERNATIVE PRESSURE BOUNDARY REQUIREMENTS DURING CLASS 1 SYSTEM PRESSURE TESTS, REQUEST FOR ALTERNATIVE RELIEF REQUEST PT-3-01 Specific Description of Areas Affected The following is specific information pertaining to the various Class 1 pressure boundary segments for which relief has been requested.
RCS Vent and Drain Lines Segments Relief is requested from pressurizing piping between the inboard and outboard isolation device on small size vent and drain lines. These RCS vent and drain piping segments provide the design required double isolation barrier for the reactor coolant pressure boundary through the use of double manual isolation valves. In normal plant operation both of the vent and drain isolation valves are maintained in a closed position. As a result, the outboard valve only sees pressure if the inboard valve is open or leaks by the seat. Seat leakage, although undesirable, is not indicative of a flaw in the pressure boundary. The IWB-5222(b) required leakage test of these piping segments in Mode 3 would require the opening of the first isolation valve at the normal operating RCS temperature and pressure conditions. In so doing, the design requirement for two primary coolant pressure boundary isolation devices would be violated.
Additionally, opening these valves introduces the potential risk for spills and personnel contamination and since these RCS vent and drain valves are located in close proximity to RCS loop piping, personnel positioning these valves would have to enter high radiation areas within Containment. In addition to this end of inspection interval system leakage test, these RCS vent and drain piping segments are inspected, as required by IWB-5222(a), by a similar system leakage test at the conclusion of each refueling outage. For these tests, the system leakage test is conducted with the RCS drain and vent valves in their normal position (closed position). No external or visible leakage is allowed for the test to be acceptable. Since this type of test will assure that the combined first and second isolation devices are effective in maintaining the reactor coolant pressure boundary at normal operating temperature and pressure, any increase in safety achieved from the configuration required by IWB-5222(b) is not commensurate with the hardship of performing such testing.
Shutdown Cooling Suction Segment The shutdown cooling suction line consists of piping between the two shutdown cooling suction valves MOV-651 and MOV-652. These valves are administratively controlled to remain closed when the RCS is pressurized above 260 psia. A control interlock prevents opening of the valves from the Control Room with RCS pressures above 309 psia as required by Calvert Cliffs Technical Specifications. Thus, in order to achieve the full pressurization conditions as required by IWB-5222(b), a temporary configuration would have to be installed.
At the conclusion of each refueling outage this entire shutdown cooling suction piping segment is examined as part of the Class 1 system examination [IWB-5222(a)]. No external or visible leakage is allowed for the test to be acceptable. This line is also subject to periodic containment local leak rate testing which tests each valves containment isolation capability. These tests, combined with the periodic nondestructive examination prescribed by Calvert Cliffs in-service inspection program, provide assurance that the combined first and second isolation valves and the piping between are effective in maintaining the integrity of the reactor coolant pressure boundary. Any further increase in safety achieved from the configuration required by IWB-5222(b) is not commensurate with the hardship of performing such testing.
Safety Injection Header Segments These piping segments provide the flow path for safety injection tank, high pressure and low pressure safety injection, and shutdown cooling supply to the RCS. Associated fill, vent, drain, and instrument 2
ATTACHMENT (1)
ALTERNATIVE PRESSURE BOUNDARY REQUIREMENTS DURING CLASS 1 SYSTEM PRESSURE TESTS, REQUEST FOR ALTERNATIVE RELIEF REQUEST PT-3-01 lines are also included within these segments. The primary isolation devices are 12 inch loop check valves oriented to flow into the RCS. The piping segments provide the design required double isolation barrier for the reactor coolant pressure boundary. These lines are all statically pressurized during normal operation at safety injection tank pressure and are monitored for leakage by pressure and level indications and associated alarms. Additionally these lines are visually examined both during the RCS system leakage test as Class 1 boundary lines and during the Class 2 high pressure safety injection system leakage test. No external or visible leakage is allowed for these tests to be acceptable. Since this testing will assure that the pressure boundary is effective, the increase in safety achieved from the configuration required by IWB-5222(b) is not commensurate with the hardship of performing such testing.
Proposed Alternative and Basis for Use Proposed Alternative Calvert Cliffs will conduct the required end of interval system pressure tests as prescribed by Table IWB-2500-1, Examination Category B-P, using the boundary conditions and full examination coverage of IWB-5222(a). In addition those Class 1 pressure boundary portions of the systems described above that are statically pressurized during normal operation and/or pressurized during the high pressure safety injection system functional pressure test will be visually examined during both the RCS system leakage test and the functional pressure test conditions.
Duration of Proposed Alternative The proposed alternative will be implemented for the remainder of the Third Ten-Year In-Service Inspection interval.
Basis for Use 10 CFR 50.55a(a)(3) states:
Proposed alternatives to the requirements of paragraphs (c), (d), (e), (f), (g), and (h) of this section or portions thereof may be used when authorized by the Director, Office of Nuclear Reactor Regulation, or Director, Office of New Reactors, as appropriate. The applicant shall demonstrate that:
(i) The proposed alternatives would provide an acceptable level of quality and safety, or (ii) Compliance with specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The objective of the required extended pressure boundary conditions is to detect evidence of leakage and thereby verify the integrity of the RCS pressure boundary beyond the first isolation valve. As discussed above, Calvert Cliffs believes that in order to meet the requirement of IWB-5222(b), the establishment of and the return from the required temporary configuration will involve considerable time to accomplish, result in unwarranted increase in worker radiation exposure, and will risk delay of normal plant startup following the refueling operation. All of these actions constitute a hardship without a compensating increase in the level of quality and safety. Therefore Calvert Cliffs requests authorization to perform the requested alternative to the code requirement pursuant to 10CFR 50.55a(a)(3)(ii).
3