ML19208A923
| ML19208A923 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/03/1979 |
| From: | Sherwood G GENERAL ELECTRIC CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| MFN-199-79, NUDOCS 7909180290 | |
| Download: ML19208A923 (2) | |
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GENERALh ELECTRIC NUCLEAR ENERGY PROJECTS DIVISION GENERAL ELECTRIC COMPANY,175 CURTNER AVE _, SAN JOSE. CALIFORNIA 95125 C
August 3, 1979 i
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MFN-199-79 U. S. Nuclear Regulatory Commission
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Office of Nuclear Regulation Q '\\ (
Washington, D.C.
20555 Attention: Harold R. Denton, Director y
SUBJECT:
INERTING 0F BWR MARK I & II CONTAINMENTS 1
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Gentlemen:
This letter is to appeal the proposed ruling for inerting BWR ~iark I and II containments contained in the NRC Lessons Learned Task Force, NUREG-0578.
We believe that inerting will not add to the safety of the Mark I andill containments.
General Electric recognizes the NRC must take action to reduce and remove the uncertainties related to the TMI accident; however, we believe that the proposed ruling on inerting in the BWR Mark I and II is counter productive to safety, and does not logically follow from the observations of the.TMI incident. The reasons for our appeal are as follow:
o The ;equence of events at TMI, incluuing operator action, led to a cessation of core flow. This apparently caused stagnant voiding of the core, elevated zirconium tempera-I tures, and hydrogen was generated by,the chemical reaction i between zirconium and steam.
Mr tr,e operating BWR's there; is no known sequence of eventst including operator actions,-
that can cause a cessation of core flow when water inventory is available.
Core flow is greatest in the jet-pump type. of BWR, but even in the BWR 2, core flow is more than adequate to prevent fuel damage. This was demonst ated during the Oyster Creek transient of May 2, 1979. Therefore, the probability of core damage of the m>1nitude of TMI is highly unlikely for any of our BWR's.
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U. S. Nuclear Regulatory Commission MFN -199-79 August 3, 1979 Page 2 o
Even if a TMI event were postulated for the BWR, no significant hydrogen would be released because of the inherent BWR hydraulic characteristics resulting in the' core remaining covered with water. Studies show that if hydrogen up to 12% by volume were burned inside the '
containment, the design pressure would not be exceeded.
o The impact on utilities of inerting are substantial in-cluding limiting containment accessibilii.y, and probably most important, increasing personnel hazard.
Utilities have shown tht plant reliability is improved if contaiti-ment access is available for periodic checks and main tenance.
o The proposed NRC rule is premature because the NRC staff has not considered GE and licensee arguments in making a recommendation for inerting. Moreover, the NRC and in-dustry will review the hydrogen generation issue as part of ANS 56.1; therefore, NRC v.tions should await these !
recomme..dations.
In summary, we believe that both analyses and tests (as well as operating plant events) have shown that inerting is not necessary, and there is substantial margin in BWR Mark I and Mark II containments.
As we stated above, the twc most important factors which argue against inerting BWR containments are:
(a) superior BWR core protection which assures.no significant hydrogen release for an event similar to TMI, and (b) inert-ing cannot be justified on e risk-benefit basis.
If inerting is required, all light water con _tainments should be included. The proposed ruling, because of these aqfrents, appears discriminatory to the BWR.
We recommend that the NRC not propose inerting of Mark I and Mark II con-tainments since this does not provide a benefit equivalent to the cost and human hazard to operators, and does not change the risk to the public. We would be pleased to elaborate on the,detai.ls and our reasoning at your con-s venience.
Very truly yours, t
Glenn G. Sherwood, Manager Safety and Licensing Operation ljb cc: R.,.Mattson
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tA7. Ross D. Eisenhut V. Stello D10,CS I