ML093100130

EPU - Draft RAI on Licensee'S 8/21/09 Response to Questions Regarding High Energy Line Break

ML093100130
Person / Time
Site:	Monticello
Issue date:	11/05/2009
From:	Tam P Plant Licensing Branch III
To:	Gunderson L, Loeffler R, Salamon G Northern States Power Co
Tam P
References
TAC MD9990
Download: ML093100130 (2)

Text

Accession No. ML093100130 From: Tam, Peter Sent: Thursday, November 05, 2009 7:34 AM To: 'Gunderson, Lynne'; 'Salamon, Gabor'; 'Loeffler, Richard A.'

Cc: Khanna, Meena; Tsirigotis, Alexander; Pascarelli, Robert

Subject:

Monticello EPU - Draft RAI on your 8/21/09 response (TAC MD9990)

Lynne:

In the 8/21/09 response (L-MT-09-044) to an RAI, the licensee confirmed that the criteria and requirements for high energy line breaks (HELBs) are based on the December 18, 1972 Giambusso letter; Standard Review Plan (SRP) 3.6.1 Rev. 1, July 1981; SRP 3.6.2 Rev. 1, July 1981 and Generic Letter 87-11 which allow elimination of the arbitrary intermediate pipe breaks. These criteria all define that a high energy line is a line which has a maximum operating temperature greater than 200°F or a maximum operating pressure greater than 275 psig. Although MNGP USAR Appendix I,Section I.1 has a statement which shows that the above criteria are used for the determination of high energy lines and the effects of the postulated breaks on these lines, the response to RAI No. 4 stated that: "The criteria for HELB consideration at Monticello are for piping systems that are >275 psig and >200°F, see USAR Appendix I.2. This is based on United States Atomic Energy Commission - Safety Evaluation by the Directorate of Licensing, Docket No. 50-263, Monticello Nuclear Generating Plant -

Analysis of the Consequences of High Energy Piping Failures Outside Containment, July 29, 1974,,,,"

We reviewed the MNGP USAR and the Atomic Energy Commission (AEC) Safety Evaluation (SE) for MNGP. We note that the AEC SE indicates that the criteria and requirements for HELB are included in the December 18, 1972, letter (the Giambusso letter). The Giambusso letter provided the definition of high-energy piping systems. It was worded Protection from pipe whip need not be provided (emphasis added) if both of the following piping system conditions are met: (1) the service temperature is less than 200F; and (emphasis added) (2) the design pressure is 275 psig or less. This obviously means that high-energy piping systems are those systems for which either the maximum service temperature is greater than 200OF or the maximum service pressure is greater than 275 psig. When the SRP was issued in November 1975 (NUREG-75/087), Section 3.6.1 of the SRP maintained this criterion and showed that systems that only meet one of the conditions (temperature or pressure) are considered high-energy systems. The AEC SE for MNGP specifically states that, A summary of the criteria and requirements included in our letter of December 18, 1972, is set forth below. What follows in the SE after this statement includes the following: Protection should be provided from ruptures in pipes carrying high energy fluid, where the temperature and pressure conditions of the fluid exceed 200 oF and 275 psig, respectively The and between 200 oF and 275 psig is not correct and appears to be a typo and the licensee misinterpreted the criteria and used an and instead of an or. The licensee is requested to provide a resolution for this apparent misinterpretation.

Please set up a conference call with me to discuss the above. This e-mail aims solely to prepare you and others for the proposed conference call. This e-mail does not formally convey an NRC staff position, and does not formally request for additional information.

Peter S. Tam, Senior Project Manager

Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Tel. 301-415-1451