ML20059M961
| ML20059M961 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 11/05/1993 |
| From: | Feigenbaum T NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-88-17, NYN-93154, NUDOCS 9311300019 | |
| Download: ML20059M961 (3) | |
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Seab o k NH 03874 Telephone (603)474-9521 Facsimile (603)474-2987 i
Energy Service Corporation Ted C. Feigenbaum Seni r Vice President and NYN-93154 Chief Nuclear Officer
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November 5,1993 U.S. Nuclear Regulatory Commission
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Washington, L).C. 20555
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Attention:
Document Control Desk
References:
(a)
Facility Operating License No. NPF-86, Docket No. 50-443 (b)
NRC Generic Letter 88-17, dated October 17, l'988, " Loss of Decay Heat Removal" (c)
Pub!h: Service of New Hampshire, New Ifampshire-Yankee Division (NHY)
Letter NYN-89012 dated February 3,1989, " Response to Generic Letter 88-17,"
G.S. Thomas to USNRC
.i (d)
Public. Service of New Hampshire, New Hampshire Yankee Division (NiiY)-
Letter NYN-89001 dated January 3,1989, " Response to Generic'. Letter 88-17,"
G.S. Tim:nas to USNRC
Subject:
Revised Commitment Related to Generic Letter 88-17 Gentlemen:
The purpose of this letter is to notify the NRC that' North Atlantic has revised a commitment made in Reference (c) regarding the use of a temporary sight glass (tygon hose) during Reactor Coolant System (RCS) reduced inventory conditions at Seabrook Station.
Generic Letter (GL) 88-17 requested licensees to take actions to reduce the probability of occurrence or consequences of loss of decay heat removal. One of the requested actions was to provide at least two independent, continuous RCS water level indications whenever the RCS is in a reduced inventory condition with irradiated fuel in the reactor vessel.
References (c) and (d) provided information pursuant to 10 CFR 50.54(f) regarding actions taken or planned in response to GL 88-17 at Seabrook Station. Three RCS level indications are used at Seabrook Station during reduced RCS inventory conditions. They are: 1) a wide range RCS level indication provided by differential pressure measurement,2) a narrow range RCS level indication provided -
by ultrasonic measurement, and 3) a sight glass (tygon tube). The wide and narrow range level sensors have overlapping spans to provide continuous level indication from a pressurizer level of approximately 30 percent to a level below the RCS pipe mid-plane.
9311300019 931105" 0500O4 3 h lD l
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November 5,1993 Attention:
Document Control Desk Page two 1
Reference (c) stated that the sight glass would not be used for RCS level monitoring following i completion of certain design modiGeations (unless the wide range level indication became unavailable).
The design modi 0 cations were: 1) installation of the narrow range level indication an'd 2) modification of the wide range level indication to increase its van and improve its accuracy. Although the design modiGcations have been completed, North Atlantic ntends to continue use of the sight glass during RCS draining and reduced inventory conditions.
Design features have been provided to ensure that both the sight glass and the wide range level-indication are accurate and reliable. The sight glass and vide range level transmitter are both referenced to the pressurizer steam space. This feature ensures that both level instruments are measuring the same parameter. It also precludes inaccurate level indication resulting fnm a pressure differebec between then RCS and the Containment atmosphere. Permanent reference-level elegt%n marks have,been provided in the Containment Building to facilitate sight glass readings. In addition to efet&n narks, signiGcant '
levels such as the pressurizer lower instrume~ tap, reactor vessel Gange, RCS pipe to, mid-loop, and bottom have been indicated.
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- Procedural requirements ensure that the sight glass is an accurate and reliable RCy level indicator.
3 Following depressurization and venting of the RCS, the sight glass is installed in agrdance mith approved instructions. These instructions ensure that the sight glass is properly installed, Mlled. yentgl,and -
placed in service. Procedures for draining the RCS require botn the sight glass and the widirange RCS level indication to be in service prior to reducing RCS water level below the pressurizer indicatec' tevel
- range. Procedures also require agreement between sight glass, wide range and na: row range level readings -
within a speciGed tolerance during RCS draining and reducu inventory conditions. Finally, procedures'-
specify the required action to be taken in the event that any tu level measurements disagree beyond the cllowed tolerance.
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- n the design features and procedural requirements summarized above, North Atlantic concludes to
, $t glass will provide a highly reliable, redundant and diverse indication of RCS water level during Kt. m:aining and reduced inventory conditions. North Atlantic concludes that use of the sight glass during RCS draining'and reduced inventory conditions is a conservative measure to provide further assurance that decay heat removal capability will be maintained.
Should you have any questions en this matter, please contact Mr. James M. Peschel, Regulatory Compliance Manager at (603) 474-9521 extension 3772.
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Ver(truly yours,
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Ted C. Feigenbaum/
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U.S. Nuclear Regulatory Commission November 5,1993
' Attention:
Document Control Desk Page three
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Mr. Thomas T. Martin R:gional Administrator U.S. Nuclear Regulatory Commission Region 1 475 Allendale Road King of Prussia, PA 19406 Mr. Albert W. De Agazio, Sr. Project Manager.
Project Directorate 1-4 Division of Reactor Projects U.S. Nuclear Regulatory Commission l
Washington, DC 20555 Mr. Noel Dudley i
NRC Senior Resident inspector
' P.O. Box 1149 Seabrook, NII 03874 b
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