ML110410627
| ML110410627 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 02/10/2011 |
| From: | Barkley R NRC Region 1 |
| To: | Grinnell D C-10 Research & Education Foundation |
| Barkley R | |
| References | |
| Download: ML110410627 (3) | |
Text
February 10, 2011 Debbie Grinnell Research Advocate C-10 Research & Education Foundation, Inc.
44 Merrimac Street Newburyport, MA 01950
Dear Ms. Grinnell:
I am responding to several questions you provided to me verbally regarding gaseous releases from Seabrook Station, particularly in the 2007 - 2009 time period. At that time, you were concerned with the increase in the duration (including one 90-hour batch release) and the number of such releases (an approximate doubling since 2003), and asked why these releases occurred. In addition, you subsequently provided several specific questions to others in this office regarding steam generator inspection activities conducted during the 2009 refueling outage. In order to address your concerns, one of our health physicists looked into this matter during a regularly scheduled inspection in early December 2010. His observations are discussed below.
Unfortunately, I was not able to directly reach you at the C-10 office number in December and early January to provide an answer to your questions verbally. During our discussions in late January, you requested that I provide this response in writing or via email.
All of the releases that occurred were procedurally controlled by the licensee and while they constituted an increase over the number of prior year releases, these releases collectively remained a very small fraction of NRC regulatory limits. The increase in releases, both in duration and number, were attributed to operational and maintenance factors described below, and not to other factors such as changes in plant power output or an increase in fuel cladding failures.
With regard to the releases in question, we note that Seabrook Station operates on an 18-month fuel cycle. Thus the plant shut down in the fall of 2006, the spring of 2008 and the fall of 2009 for refueling, equipment inspections, and maintenance/surveillance testing. During these outages, the containment system is vented to the atmosphere at various times to equalize pressure between the interior and exterior of containment for ease of entry and exit. Between outages, containment purges, which constitute batch releases, also occurred on a number of occasions to maintain pressure and temperature within the proper range.
Due to problems experienced during 2008 - 2009 with the component cooling water system in containment (which removes containment heat in normal operation), the number of releases in this interval increased. In addition, during operations in 2009, a number of maintenance and operational activities were conducted on air and water cooling systems that have a release pathway to the environment. During these activities, or subsequent testing of these systems, releases categorized as batch releases occurred. Operation and testing of these systems while
D. Grinnell 2
the plant was at power released radioisotopes with short half-lives, such as Ar-41 and Xe-133, resulting in larger batch releases than if performed while the plant was shutdown. The specific plant evolution that resulted in the 90-hour batch release was not researched since the cumulative release was a very small fraction of NRC regulatory release limits and the inspector had other assigned priorities.
Also, during the fall 2009 outage, Seabrook conducted steam generator inspections, as required by NRC Technical Specifications, between October 2 - 19. As is typical of most licensees, Seabrook Station inspected the secondary side of the steam generators during the first several days of this period, removing accumulated secondary side corrosion products during that time, then spent the bulk of the later part of this period (October 9 - 19) conducting eddy current examinations of selected steam generator tubes from the primary side access manways.
Finally, I noted that you asked a series of questions related to temperature monitoring of the Independent Spent Fuel Storage Installation casks at Seabrook, since such temperature monitoring is required to ensure that passive cooling of the internal portion of the cask is occurring as designed. Since your questions were directed to Ms. Kristina Banovac in our Headquarters Office of Nuclear Materials Safety and Safeguards, that office is preparing a reply to you in this matter.
I trust we have answered your questions in this matter. Please contact me at (610) 337-5065 if you have future questions regarding the operation of Seabrook Station.
Sincerely,
/RA/
Richard S. Barkley, PE Technical Communications Assistant
ML110410627 After declaring this document AAn Official Agency Record@ it will be released to the Public.
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