ML19350B581
| ML19350B581 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah, McGuire  |
| Issue date: | 02/19/1981 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Atomic Safety and Licensing Board Panel |
| Shared Package | |
| ML19247D089 | List: |
| References | |
| TASK-AS, TASK-BN-81-02, TASK-BN-81-2 BN--81-02, BN-81-2, NUDOCS 8103230058 | |
| Download: ML19350B581 (2) | |
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Docket No.: 50-359 MEMORANDUM FOR: The Atomic Safety and Licensing Board for the McGuire Nuclear Station, Unit 1 FROM:
Robert L. Tedesco, Assistant Director for Licensing, DL
SUBJECT:
BOARD NOTIFICATION - HYDROGEN CONTROL MEASURES FOR SE000YAH (BN 81-02)
We are forwarding the following documents for your information:
1.
Memorandum, T. E. Murley to D. Eisenhut, February 10, 1981, with rough draft - Sandia Report " Analysis of Hydrogen Mitigation for Degraded Core Accident in the Sequoyah Nuclear Power Plant (Dec.1,1980),
2.
Memorandum, E. J. Hanrahan to the Comission, Jan. 22, 1981, with a report entitled " Evaluation of the Glow Plug Igniter Concept for use in the Sequoyah Nuclear Plant."
Both documents present singular views regarding :the use of specific hydrogen control maasures for the Sequoyah Nuclear Plant which utilizes a similar ice condenser containment design as in the McGuire Nuclear Station. The staff in its current review and evaluation of the Interim Distribution Ignition System will consider the views presented in these documents. We will continue to keep you infonred on this matter.
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Robert L. Tedesco, Assistant Directer for Licensing Division of Licensing
Enclosures:
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MEMORANDUM FOR:f-YTisenhut, Director Division of Licensing Office of t'uclear Reactor Regulation FROM:
Thomas E. Murley, Director Division of Safety Technology Office of Nuclear Reactor Regulation
SUBJECT:
SUCMITTAL OF ROUGH DRAFT-SANDIA REPORT"At;ALYSIS OF HYDROGEN MITIGATION FOR DEGRADED CORE ACCIDENTS Irl THE SEQUOYAH NUCLEAR POWER PLANT (DECEMBER 1, 1980)
FOR ASLB NOTIFICATION CONSIDERATION Discussion The interim distributed ignition system (IDIS) proposed by TVA and found acceptable by the staff for operation is the interim solution to the issue of hydrogen control for degraded core accidents. TVA in the design and installation of the IDIS has located 4 glow plug igniters in the upper plenum of the ice condenser sectton of the containment.
Sandia National Laboratory in the rough draf t report entitled, " Analysis of Hydrogen Mitigatiun for Degraded Core Accidents in the Sequoyah Nuclear Power Plant," December 1,1980, has recommended that the igniters located in the upper plenum be removed. Their basis for the recommendation is that there may be accident scenarios where the lower' compartment atmosphere is steam inerted or oxygen deficient.
Thus, the flow through the ice bed may exit with highly enriched hydrogen concentrations, concentrations high enough to be detonable (Sandia considers 18% as the lower limit of detonability). Sandia is concerned about the effects of detonations in the upper plenum region.
The staff previously considered this issue of igniter location and concluded that 1) typical small break analysis has not shown the lower compartment to be steam inerted or oxygen deficient; 2) TVA has considered the effects of detonations in the upper plenum and concluded that the effects are minimal and would not result in breach of containment; and 3) locating igniters in the upper plenum is beneficial for reducing the hydrogen accumulation in the upper compartment.
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D. Eisenhut However, as a result of my review of the draft Sandia report, I have recozmende of ice condenser plants be evaluated in more detail in th Since this rough draft document recommends an action suggesting the staff p on the upper plenum igniters may be unconservative, we recommend it be considere for submittal to any ASL Boards presently hearing operating license proceed or those hearing operating license amendments considering Hydrogen Control and Mitigation.
This is in conformance with NRR Office Letter 19, Revision 1-Procedures for Notification to Licensing Boards of Relevant and Material New Information.
TV Thomas 2. Murley, rector Division of Safety Technology Office of Nuclear Reactor Regulation
Enclosure:
Memorandum T. Murley to D. Ross dtd Feb. 9,19e l
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MEMORANDUM FOR: Denwood F. Ross, Jr., Director Division of Systems Integration a
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Thomas E. Murley, Director Division of Safety Technology
SUBJECT:
LCCATION OF IGNITERS IN ICE CONDENSER PLANTS I believe that further analysis is needed to deal with Sandia's concerns on i
the location of igniters in ice condenser plants. Specifically, tney state in NUREG/CR-1762,, Rough Draf t dated December 1,1980, the following:
Under certain accident conditions, the lower compartment could be inerted either by high' concentrations of steam, j
or by-low concentrations of oxygen. If this should occur, the interim deliberate ignition system (IDIS) as presently planned for Sequoyah has a serious shortcoming. The inerted gas mixture e1tering the bottom of the ice condensers will.
I emerge as an extremely rich mixture at the top. Concentrations i
could approaca or exceed the detonability limits in a toroidal I
region around the periphery at the top of the ice condensers.
Four igniters are presently planned for this region. ge, strongly recommend that those igniters be removed.
- Instead, we suggest tnat upper compartment deliverage ignition strategy should attempt to burn lean mixt'.::es high in the upper ccmpartment."
(emphasisadded)
If Sandia is correct that igniters are intended to be placed at the top of i
the ice condensers, then I believe their recommendation should be evaluated l
in more detail. In my judgment, it is unlikely that we will be able to show l
that inerted conditions cannot exist in the lower compartment. Sandia states that steam inerting can occur with steam fractions of 30-56 percent, depending on hydrogen concentration.
Under these circumstances, we would have to con-sider the possibility of a detonation in the upper plenum.
I don't believe this accident sequence is sufficiently probable that we need to modify ur-position regarding Sequoyah at this time. However, I believe h
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Denwood F. Ross, Jr.
2 FEB 9 TAl we should evaluate the pros and cons of igniters of further testing and analysis we are planning.
l Please keep me informed of your progress ortthis issue.
.s Thomas E. Murit y, Director Division of Safity Technology cc:
H. Denton D. Eisenhut e
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