NL-10-0618, Lsi Program Alternative HNP-ISI-ALT-09 Version 2
| ML100890051 | |
| Person / Time | |
|---|---|
| Site: | Hatch, South Texas  |
| Issue date: | 03/29/2010 |
| From: | Ajluni M Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-10-0618, TAC ME3327 | |
| Download: ML100890051 (9) | |
Text
Southern Nucleii' Operatmg (.ompllIlY. Inc March 29, 2010 SOUTHERN'\'
COMPANY rJl(;gl' (If ~)er[l!' }~!lf}' \-t 0 rltl Docket Nos.: 50-366 NL-10-0618 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant-Unit 2 lSI Program Alternative HNP-ISI-AL T-09 Version 2 Ladies and Gentlemen:
On February 16, 2010 Southern Nuclear Operating Company (SNC) proposed a code alternative for the Edwin I. Hatch Nuclear Plant (HNP)-Units 1 and 2.
Following discussions with NRC project management, SNC has revised the scope of the proposed alternative. This letter supersedes in its entirety, our submittal of February 16, 2010 contained in letter NL-10-0246 and is applicable for the HNP-Unit 2 maintenance shutdown of April 2010. Prior to SNC superseding the previous request, the NRC requested additional or supplemental information by letter dated March 23,2010. (TAC ME3327 and ME3328). This requested information is provided in Enclosure 1 to this letter. Enclosure 2 provides proposed Code Alternative HNP-ISI-ALT-09, Version 2.
Pursuant to 10 CFR 50.55a(a)(3)(ii), SNC hereby requests approval of an alternative to the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI, 2001 Edition through 2003 Addenda, Subsection IWB-5221 (a). SNC requests NRC approval of proposed Alternative HNP-ISI-ALT-09, Version 2, to perform the VT-2 visual examination during a system leakage test of Class 1 components with mechanical joint connections at a pressure lower than the Code required pressure following repair and replacement activities. This alternative is requested because compliance with the specified requirements would result in hardship without a compensating increase in the level of quality and safety.
According to 10 CFR50.55a(a)(3}, alternatives to the requirements of paragraph 50.55a(g) may be used, when authorized by the NRC, if an applicant demonstrates that the proposed alternatives would provide an acceptable level of
U.S. Nuclear Regulatory Commission NL-10-0618 Page 2 quality and safety or if the specified requirement would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The 2001 Edition through 2003 Addenda of the ASME Code,Section XI, Table IWB-2500-1, Examination Category B-P (Item Number B 15.10) requires the performance of a system pressure test in accordance with Section IWB-5220 for all ASME Code Class 1 pressure boundary components prior to plant startup following each reactor refueling outage. Paragraph IWB-5221 (a) requires that the system leakage test be conducted at a test pressure not less than the nominal operating pressure associated with 100% rated reactor power, which for HNP is 1045 psig. The above pressure test requirements are supplemented by 10 CFR50 ..55a(b)(2)(xxvi) which invokes the requirements of IWA-4540(c) of the 1998 Edition of the ASME Section XI Code for repair/replacement activities of Class 1, 2, and 3 mechanical jOint connections. This alternative proposes performing the system leakage test of Class 1, pressure retaining, mechanical joint connections at a pressure lower than the Code required pressure (i.e., at 920 psig) following repair and replacement activities not associated with a refueling outage (See ASME Interpretation XI-1-01-19).
A maintenance shutdown has been scheduled to begin on April 5, 2010 for HNP Unit 2. As part of the maintenance shutdown activities, two safety relief valve (SRV) pilots are scheduled to be replaced. It was recently determined that one SRV is experiencing internal leakage. Because of this unforeseen condition, SNC has conservatively decided to replace that SRV main body and its associated pilot assembly during the maintenance outage scheduled to begin on April 5, 2010. At this time, it is believed that there is no Class 1 pressure boundary leakage associated with the main body that is scheduled to be replaced. One of the two replacement pilots is associated with the SRV main body replacement. This recent determination results in a need to perform testing in accordance with IWB-5221 (a) at 1045 psig without the approval of this proposed alternative. The proposed alternative is needed in order to perform the VT-2 visual leakage examination at a lower pressure. Performing leakage examination at a lower pressure results in more bearable conditions for examination personnel and should result in a higher quality examination. The proposed alternative for pressure testing at 920 psig would allow detection of leakage if the mechanical joint connections are not leak tight.
The NRC has approved several similar relief requests for performing pressure tests at less than nominal operating pressure. A similar relief request was submitted for Pilgrim Nuclear Power Station. This approval was documented in the NRC letter of June 29, 2006 (TAC NO. MC8286). Hope Creek submitted a relief request on March 23, 2004, supplemented by a letter of May 18, 2004, with NRC approval granted on August 27,2004 (TAC No. MC2396. ML042010250).
Monticello submitted a relief request on August 27, 2003 and NRC approval was received in the letter of March 25,2004 (TAC No. MC0593, ML040700415).
Cooper submitted a relief request on January 9, 1998 which was approved by NRC letter dated February 26, 1998 (TAC No. MA0677).
u.s. Nuclear Regulatory Commission NL-10-0618 Page 3 Expedited approval of the proposed alternative is requested on or before April 9,2010 to allow the use of this proposed alternative for the Hatch-Unit 2 maintenance shutdown of April 2010.
This letter contains no NRC commitments. If you have any questions, please advise.
Respectfully submitted,
~ ~Of-.
M. J. Ajluni Manager - Nuclear Licensing MJA/PAH/phr
Enclosure:
1). Supplemental Information Requested by NRC Letter of March 23, 2010 2). Request for Alternative HNP-ISI-AL T-09, Version 2 cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. D. R. Madison, Vice President - Hatch Ms. P. M. Marino, Vice President - Engineering RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Hatch Mr. E. D. Morris, Senior Resident Inspector - Hatch Mr. P. Boyle, NRR Project Manager
ENCLOSURE 1 Edwin I Hatch Nuclear Plant-Unit 2 Supplemental Information Requested by NRC Letter of March 23, 2010
U.S. Nuclear Regulatory Commission NL-10-0618 Page 1 of Enclosure 1 Supplemental Information Requested by NRC Letter of March 23, 2010 NRC Request # I:
Provide clarification of the intent of your application with respect to whether an alternative is being proposed to the requirements of 10 CFR 50.55a(g) as it relates to the applicable Edition of the AS ME Code for HNP and the requirement stated in 10 CFR 50.55a(b)(2)(xxvi) for the pressure testing of mechanical joints. For example, the discussion in your application suggests that your application is applicable to mechanical joints, whereas many of the sections of the Code cited in your application appear applicable to the requirements for inspection of welded or brazed joints.
SNC Response:
SNC has revised HNP-ISI-ALT-09 to apply only to the supplemental ASME Section XI Code requirement invoked by 10 CFR 50.55a(b)(2)(xxvi) for the pressure testing of mechanical joints.
NRC Request #2:
Provide clarification of those components the RR applies to. Currently, in one location, the RR refers to all Class I items and in another location it refers to those components that are less than one inch in size and to mechanical connections.
SNC Response:
The location that refers to one inch size was a typo. The typo has been corrected in revised HNP-ISI-ALT-09. In addition, the request has been revised to apply only to mechanical joints.
NRC Request #3 Provide detai Is of the hardship involved with performing the test at a pressure of 1045 pounds per square inch gauge (psig), versus 920 psig. Specifically, provide details regarding whether the hardship is due to occupational radiation exposure at 100 percent versus 5 percent power, personnel safety issues involved with the additional heat-up time required to perform the test at 1045 psig, unusual alignments of valves, or other considerations.
SNC Response:
SNC has revised HNP-ISI-ALT-09 to provide specific details related to the hardship involved with additional heat-up time required to achieve 1045 psig specifically for the Unit 2 forced outage and details related to performance of a cold leakage test in lieu of a hot leakage test.
ENCLOSURE 2 Edwin I Hatch Nuclear Plant-Unit 2 151 Program Alternative HNP-ISI-ALT-09, Version 2
SOUTHERN NUCLEAR OPERATING COMPANY HNP-ISI-ALT-09, VERSION 2.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(ii)
Plant Site-Edwin I. Hatch Nuclear Plant - Units 2 Unit: I I Interval 4th lSI Interval, January I, 2006 through December 31 , 20 IS Interval Dates: I I Requested Approval is requested by April 9, 2010 to support testing during a Unit 2 Date for I Approval: I maintenance shutdown that is currently scheduled to begin on AprilS, 2010.
ASMECode Class I pressure retaining mechanical joint connections which require a VT-2 I Components Affected:
examination for leakage subsequent to repairlreplacement activities.
Applicable Code Edition ASME Section XI Code, 200 I Edition through the 2003 Addenda and Addenda:
I. IW A-4S40(a) requires a hydrostatic or system leakage test, in accordance with Applicable IWA-SOOO, for repair/replacement activities performed by welding or brazing Code on a pressure retaining boundary prior to, or as part of, returning to service.
Requirements: 2. IWB-S22I (a) requires the system leakage test to be conducted at a pressure not less than the nominal pressure associated with 100% rated reactor power.
IOCFRSO.SSa(b)(2)(xxvi) Pressure Testing Class }, 2, and 3 Mechanical Joints provides supplemental code requirements to those of IW A-4S40(a) stated above.
IOCFRSO.5Sa(b)(2)(xxvi) invokes the IW A-4540(c) repair/replacement activity provisions of the 1998 Edition of Section XI for pressure testing Class I, 2, and 3 mechanical joints when using the 2001 Edition through the latest edition and addenda of ASME Section XI. Therefore, even though the lSI Code of Record applicable at Plant Hatch does not require pressure testing and VT-2 examination of mechanical joint connections, the 1998 Edition of Section XI does.
Relief is requested from the test pressure requirement of IWB-522I (a) (i.e., 1045 psig) on the basis of hardship as cited below.
- Replacement of some components installed via mechanical joints (e.g., Safety Relief Valves (SRVs), pump mechanical seals) is planned during a Reason for maintenance shutdown which is scheduled to begin April 5, 2010. These Request:
repair/replacement activities will require a VT-2 leakage examination of the mechanical joint connections during unit startup.
- Nominal operation pressure (i.e., 1045 psig) will not be achieved until approximately 14-hours after reaching 920 psig during the startup sequence:
o Control Rod Drive withdrawal limitations and the associated gradual increases in reactor power, pressure and temperature.
o Technical Specification required Pressure versus Temperature limitations.
o Main steam line piping, turbine control and stop valve warming requirements.
o Main turbine warming requirements.
o Small increases in pressure over time to provide better seating I Page 1 of:l
SOUTHERN NUCLEAR OPERATING COMPANY HNP.ISI-ALT.09, VERSION 2.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR SO.SSa(a)(3)(ii) characteristics of the SRV s.
- VT-2 leakage examination inside the drywell (primary containment) represents a hardship at the nominal operating pressure of 1045 psig during start-up because of high ambient and component temperatures.
o Data was retrieved for a previous shutdown (5/2008) using instrumentation approximately 8 ft higher in elevation than the SRVs.
- Ambient temperature was approximately 143 degrees Fahrenheit once reaching 920 psig.
- Data shows ambient temperature increases to approximately 156 degrees Fahrenheit over a 14-hour period while holding pressure steady at 920 psig.
o The expected time during a maintenance shutdown to increase pressure from 920 psig to 1045 psig is approximately 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br />, therefore a ambient temperature increase of 13 degrees would be expected.
- Reactor Coolant System (ReS) nominal operating pressure results in drywell ambient temperatures that require special safety precautions such as ice vests and cool air supply lines for personnel performing the VT -2 examinations.
- These adverse conditions could also compromise the quality of the leakage examination due to the hardship imposed on examination personnel.
- Performance of a cold leakage test (non nuclear heat-up), such as that required following a refueling outage is not conducive following a maintenance shutdown as described below.
o Main Stearn Lines are flooded with Main Stearn Isolation Valves closed.
o The reactor pressure vessel (RPV) is required to be virtually water solid.
o Extensive valve manipulations, system lineups, and procedural controls are required in order to heat up and pressurize the ReS to establish the necessary test pressure.
o The additional valve lineups and system reconfigurations necessary to support this test will impose an additional challenge to the affected systems. A normal plant startup would then occur, after completion and subsequent recovery from the cold leakage test.
o Performing a cold leakage test would add approximately 2-days to the shutdown duration.
Plant Hatch will perform the required VT-2 leakage examination for any repairl replacement activities of mechanical joint connections performed during the April, 2010 maintenance shutdown at a ReS pressure of ~ 920 psig.
Proposed Disposition of any observed leakage will consider the marginal increase in Alternative leakage rates that might occur at the nominal operating pressure associated with and Basis for 100% rated reactor power (i.e., 1045 psig) and the actual reactor pressure when Use: the examination was performed.
In addition, dry well monitoring systems would detect leakage that might occur in mechanical joint connects at higher pressures associated with nominal reactor.
operation. These systems include drywell air temperature and pressure Page 2 of3
SOUTHERN NUCLEAR OPERATING COMPANY HNP*ISI*AL T*09, VERSION 2.0 PROPOSED ALTERNATIVE IN ACCORDANCE WITH 10 CFR 50.55a(a)(3)(ii) monitoring and the drywell floor and equipment drain sumps.
Since the RCS boundary is subjected to a leakage test and visual examination at nominal operating pressure (i.e., 1045 psig) near the end of every refueling outage and monitoring systems detect leakage inside the drywell, a leakage test and visual examination performed at 920 psig for the repair/replacement of mechanical joint connections provides adequate assurance of structural and pressure boundary integrity. Therefore, this proposed alternative should be I
granted pursuant to 10 CFR 50.55a(a)(3)(ii).
Duration of The Hatch Unit 2 maintenance shutdown currently scheduled to begin on April 5, Proposed Alternative: 2010.
- 1. Entergy Nuclear Northeast Pilgrim Nuclear Power Station 4th 10-Year Interval lSI Program Relief Request PRR-2, NRC T AC NO. MC8286 dated June 29, 2006.
- 2. Nuclear Management Company Monticello Nuclear Generating Plant 3rd 10 Year Interval lSI Program Relief Request RR-17, NRC TAC NO. MC0593 dated March 25, 2004
References:
- 3. PSEG Nuclear, LLC, Hope Creek Nuclear Generating Station, 2 nd IO-Year Interval lSI Program Relief Request HC-RR-12-023, NRC T AC No. MC2396 dated August 27, 2004
- 4. Nebraska Public Power District, Cooper Nuclear Station, 3rd 10-Year Interval lSI Program Relief Request PR-IO, NRC T AC No. MA0677 dated February 26, 1998.
i iting approval Page 3 of3