ML103480632

Email, Request for Information, Round 3, License Amendment Request to Approve FSAR Change for Leak-Before-Break of the Pressurizer Surge Line

ML103480632
Person / Time
Site:	Waterford
Issue date:	12/14/2010
From:	Kalyanam N Plant Licensing Branch IV
To:	Sharon Bennett, Steelman W Entergy Operations
Kalyanam N, NRR/DORL/LPL4, 415-1480
References
TAC ME3420
Download: ML103480632 (1)

Text

From: Kalyanam, Kaly Sent: Tuesday, December 14, 2010 9:17 AM To: STEELMAN, WILLIAM J; BENNETT, STEVE A Cc: Lent, Susan; Burkhardt, Janet

Subject:

FW: RAI Response from Entergy for the Waterford 3 Surge Line LBB questions Attachments: 10-0083.pdf The SUNSI information is as follows:

Plant: Waterford Steam Electric Station, Unit 3 Docket No.: 50/382

Subject:

RAI on License Amendment Request for Approval of Leak-Before-Break of the Pressurizer Surge Line TAC No.: ME3420 SUNSI Review Done: Yes. Publicly Available, Normal Release, Non-sensitive, From: N. Kalyanam To: W. Steelman/S. Bennett W. Steelman/S. Bennett, On reviewing the Supplement dated November 23, 2010, the Nuclear Regulatory Commission Staff has the following additional requests for information:

Please provide the response at the earliest to support the need date of Entergy.

Thanks Kaly N. Kalyanam PM, Waterford 3 and Arkansas Nuclear One - Units 1 and 2

1. The response to NRC RAI-2 in Attachment 1 to the letter dated Entergy November 23, 2010, states:

The existing Waterford 3 TS LCO 3.4.5.1 provides the instrumentation necessary by RG 1.45 to detect RCS leakage for compliance with GDC 30. The leakage detection design requirements under GDC 4 assure that capability exists to detect an assumed leakage flaw (2.5 gpm) by a factor of 10 (0.25 gpm). This design capability is for the specifically analyzed Waterford 3 pressurizer surge line piping system under GDC 4 using deterministic fracture mechanics analysis. For compliance to SRP 3.6.3, Waterford 3

credits the containment sump level instrument which is one of the GDC 30 leakage detection instruments in TS LCO 3.4.5.1.

This response does not clearly identify the containment sump monitoring capabilities that would be required to consider the instrument Operable for TS LCO 3.4.5.1. Together, GDC 30, GDC 31, and GDC 4 specify that all parts of the reactor coolant pressure boundary be designed and installed to have a low probability of failure, the plant be designed with a means of detecting reactor coolant leakage, and the plant be designed with protection against dynamic effects of reactor coolant system piping ruptures. These design elements provide defense-in-depth. A modification to GDC 4 permitted the exclusion of protection against dynamic effects from the plant design basis when the probability of piping system rupture is accepted to be extremely small (i.e., leak-before-break (LBB)). Part of the basis for this determination is detecting pressure boundary leakage early such that the plant can be cooled down and depressurized well before a leak could propagate into a pipe rupture. The license amendment request credits a plant monitoring computer point to detect leakage at a level of 0.25 gpm using the containment sump level instrument output to satisfy LBB guidance. Explain how operability of this computer point relates to TS LCO 3.4.5.1.

2. The response to NRC RAI-2 in Attachment 1 to the letter dated Entergy November 23, 2010, states:

The establishment of a factor of 10 below the leakage flaw size provides conservative leakage detection sensitivity for meeting the guidance of SRP 3.6.3, but does not establish the need for a lower detection requirement as a new design basis limiting condition. Hence, the RCS leakage detection capability requirement in accordance with the guidance of SRP 3.6.3 does not represent a significant degradation of the RCPB that would require reduced leakage detection sensitivity in the technical specifications.

The response also cites representative industry data from EPRI MRP-109 in determining that the existing RCS leakage TS LCO 3.4.5.2 limit of 1.0 gpm provides ample response time to prevent rupture. However, the response does not address how the industry data satisfies SRP 3.6.3 guidance regarding margin to account for uncertainties in the determination of leakage from postulated cracks in piping. These uncertainties include the accuracy of leakage prediction for cracks of undetermined configuration and the potential for particulate material to partially plug the crack and reduce leakage. Without adequate accounting for uncertainties, the 1.0 gpm TS LCO for unidentified leakage may not provide adequate margin to the leakage crack size considered in the LBB analysis, and, therefore, would not provide the necessary assurance that the plant could be shutdown and depressurized in time to prevent pipe rupture. The response to Question 3 from the public meeting did not resolve the concern that rupture of an unrestrained pressurizer surge line could lead to a beyond-design basis accident. Thus the maintenance of a significant margin between the TS LCO for unidentified leakage and the LBB leakage crack leak rate is very important to safety. Therefore, explain how the EPRI MRP-109 data cited in the response demonstrate adequate margin to account for these types of uncertainties, or provide a revised TS LCO for unidentified leakage that provides adequate margin for uncertainties.