ML14184A958
| ML14184A958 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 06/10/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML14184A957 | List: |
| References | |
| NUDOCS 9206160421 | |
| Download: ML14184A958 (5) | |
Text
00 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OF THE THIRD TEN-YEAR INTERVAL INSERVICE INSPECTION REQUESTS FOR RELIEF NOS. I AND 2 FOR CAROLINA POWER AND LIGHT COMPANY H.B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-261
1.0 INTRODUCTION
Technical Specification 4.0.1 for H. B. Robinson Steam Electric Plant, Unit No. 2 (HBR-2), states that the inservice inspection and testing of the American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code and applicable Addenda as required by 10 CFR 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). As stated in 10 CFR 50.55a(a)(3), alternatives to the requirements of paragraph (g) may be used if (i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the third ten-year interval comply with the requirements in the latest Edition and Addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) on the date twelve months prior to the start of the 120-month inspection interval, subject to the limitations and modifications listed therein. The applicable Edition of Section XI of the ASME Code for the HBR-2 third 10-year ISI interval is the 1986 Edition. The components (including supports) may meet the requirements set forth in subsequent Editions and Addenda of the ASME Code incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein.
9206160421 920610 PDR ADOCK 05000261 P
-2 Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section XI of the ASME Code is not practical for their facility, information shall be submitted to the Commission in support of that determination and a request made for relief from the ASME Code requirement. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(i), the Commission may grant relief and may impose alternative requirements that are determined to be authorized by law, when the relief will not endanger life, property, or the common defense and security, and is otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.
The licensee, Carolina Power & Light Company, in a letter dated January 22, 1992, submitted Relief Requests 1 and 2, for the third 10-year inservice inspection (ISI) interval, which began February 19, 1992.
The staff, with technical assistance from its contractor, the Idaho National Engineering Laboratory (INEL), has evaluated the subject requests for relief in the following sections.
2.0 EVALUATION The information provided by the licensee in support of the requests for relief from impractical requirements has been evaluated and the bases for granting relief from those requirements are documented below.
A.
Request for Relief No. 1. VT-2 Examination of Class 1 Bolted Connections at Test Conditions Code Requirement: Section XI, Paragraph IWA-5242(a) requires, for systems borated for the purpose of controlling reactivity, that insulation be removed from pressure retaining bolted connections for VT-2 visual examinations performed during system pressure tests.
Section XI, Table IWB-2500-1, Examination Category B-P, Footnote 5, requires that the system leakage test (IWB-5221) be conducted prior to plant start-up following each reactor refueling outage.
Licensee's Code Relief Request: Relief is requested from removing the insulation for performance of the Code-required VT-2 visual examination of bolted connections on the Class 1 boundary while the system is at elevated temperature and pressure.
Licensee's Basis for Requesting Relief: The licensee states that in order to achieve the test pressure (2235 psig) required by paragraph IWB-5221, heat-up limitations of the Technical Specifications would require a reactor coolant system (RCS) temperature of no less than 500*F. It is not considered prudent from a personnel safety standpoint to reinstall insulation under these elevated temperature and pressure conditions. With elevated ambient temperatures.limiting stay times in
-3 the area and contact temperatures on pressure boundary components approaching 500*F, reinstallation of bolted connection insulation under these conditions is considered impractical.
Per paragraph IWA-5245, a cooldown for the purpose of conducting the visual examination (and subsequent insulation installation) is an allowed option provided the test pressure and holding period are satisfied. As stated above, this would require raising the RCS to full operating pressure and temperature and then proceeding through a cooldown operation to allow insulation replacement. This is considered an unnecessary hardship and would require an undesired RCS thermal cycle to accomplish. The time required to depressurize/cooldown, replace insulation, and return to normal operating temperature and pressure is estimated at five days.
The proposed alternative is considered to supplement and enhance the IE Bulletin 82-02 and Generic Letter 88-05 programs currently in place that address bolting integrity.
Licensee's Proposed Alternative Examination:
Insulated, pressure retaining, bolted connections shall have the insulation removed for VT-2 examination. The examination shall be conducted at the Table IWB-2500-1 frequency (each refueling outage).
However, the bolted connection VT-2 examination need not be performed in conjunction with the pressure test or while the system is at pressure.
In keeping with paragraphs IWA-2212 and IWA-5242(c), the VT-2 examination on these bolted connections will focus on discoloration, residue, boric acid accumulation, etc., or other evidence of borated water leakage.
Prior to plant start-up, following each refueling outage, these bolted connections will be reinsulated and the entire Class 1 boundary will be pressure tested in accordance with paragraph IWB-5221 and Table IWB 2500-1.
Staff Evaluation: The Code requires that a VT-2 visual examination be performed during the system leakage test each refueling outage at the test conditions (pressure and temperature) designated for that system.
For systems borated for the purpose of controlling reactivity, insulation shall be removed from pressure retaining bolted connections.
The heat-up limitations of the HBR-2 Technical Specifications require that the RCS temperature be at least 500"F for the Code-required test pressure. The licensee proposes to perform a VT-2 visual examination of the bolted connections, with the insulation removed, each refueling outage at zero or static pressure. Based on the personnel safety implications of reinstalling the insulation at elevated temperature, and the undesirable extra thermal cycle of the entire RCS if allowed to depressurize and cool down, the Code-required examination is impractical to perform.
-4 Because borated water leaves a crystalline residue, the proposed alternative examination provides a reasonable assurance that any previous leakage at bolted connections would be detected. The Code required VT-2 visual examination portion of the system leakage test, prior to plant start-up, helps detect any new leakage that may occur.
However, the system leakage test does not provide sufficient time for leakage to saturate the unremoved insulation at all bolted connections and become detectable. In addition to the licensee's proposed alternative, the system should be pressurized to nominal operating pressure for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated systems and 10 minutes for noninsulated systems prior to performing the VT-2 visual examination.
It is concluded that installing insulation during reactor operating conditions at bolted connections creates a personnel hazard due to the elevated temperature and pressure. Therefore, pursuant to 10 CFR 50.55a(g)(6)(i), relief from the VT-2 visual examination of bolted connections with insulation removed and while the system is pressurized is granted provided the licensee's proposed alternative examination is completed as stated and the systems are held at nominal operating pressure for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated systems and 10 minutes for noninsulated systems prior to performing the VT-2 visual examination and plant start-up.
B.
Request for Relief No. 2. Corrective Action for Leaking Bolted Connection Code Requirement:
Section XI, paragraph IWA-5250(a)(2) requires that if leakage occurs at a bolted connection, the bolting shall be removed, VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100.
Licensee's Code Relief Request:
Relief is requested to use the 1990 Addenda of ASME Code,Section XI, paragraph IWA-5250(a)(2).
Licensee's Basis for Requesting Relief: The licensee states that the requirement to remove all bolting when leakages are detected is not considered to be consistent with good ALARA practice, particularly regarding new assemblies, as would be the case during refueling outages.
The exposure, costs, and manpower saved by use of the 1990 Addenda would be approximately 90 percent for each assembly in question.
Various programs/procedures are currently in place at HBR-2 to monitor for leakage and corrosion so that there would be no additional nuclear safety concerns created by the use of the 1990 Addenda as requested.
The proposed alternative is judged to be as capable of detecting any significant problems as the 1986 ASME Code requirements.
Licensee's Proposed Alternative Examination:
As required by the 1990 Addenda, paragraph IWA-5250(a)(2), "If leakage occurs at a bolted connection, one of the bolts shall be removed, VT-3 examined, and evaluated in accordance with IWA-3100. The bolt selected shall be the
-5 one closest to the source of leakage. When the removed bolt has evidence of degradation, all remaining bolting in the connection shall be removed, VT-3 examined, and evaluated in accordance with IWA-3100."
Staff Evaluation: The 1986 Edition requires that all bolting be removed and VT-3 visually examined at all leaking bolted connections. The licensee's alternative examination proposes to remove the bolt closest to the leakage and when the removed bolt has evidence of degradation, all remaining bolting in the connection shall be removed, VT-3 examined, and evaluated. This proposed alternative provides an acceptable level of quality and safety in that one of the bolts that is exposed to the leakage will receive the examination and, if degradation is discovered, the remaining bolting will be removed, examined and evaluated.
Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the licensee's proposed alternative examination is authorized as requested.
3.0 CONCLUSION
Paragraph 10 CFR 50.55a(g)(4) requires that components (including supports) that are classified as ASME Code Class 1, 2, and 3 meet the requirements, except design and access provisions and preservice requirements, set forth in applicable Editions of ASME Section XI to the extent practical within the limitations of design, geometry, and materials of construction.of the components. Pursuant to 10 CFR 50.55a(g)(5)(iii), the licensee determined that conformance with certain Code requirements is impractical for his facility and submitted supporting technical justification.
Pursuant to 10 CFR 50.55a(g)(6)(i), the staff has determined that certain requirements of the Code are impractical for HBR-2, and relief may be granted for the issues described in Request for Relief No. 1 provided that the systems are held at nominal operating pressure for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated systems and 10 minutes for noninsulated systems prior to performing the VT-2 visual examination and plant start-up. This relief is being granted giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. Pursuant to 10 CFR 50.55a(a)(3)(i), the licensee's proposed alternative examination in Request for Relief No. 2 is acceptable and will provide an acceptable level of quality and safety. Such relief and alternative examinations are authorized by law, will not endanger life, property, or the common defense and security, and is otherwise in the public interest.
Principal Contributor: Tom McLellan Date:
iune 10, 1992