ML20246Q238
| ML20246Q238 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 07/17/1989 |
| From: | Long R GENERAL PUBLIC UTILITIES CORP. |
| To: | Varga S Office of Nuclear Reactor Regulation |
| References | |
| C-89-676, C000-89-0676, NUDOCS 8907210035 | |
| Download: ML20246Q238 (5) | |
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2 GPU Nuclear Corporation
' NUCIMF One Upper Pond Road Parsippany, New Jersey 07054 i.
201-316-7000 TELEX 136-482 Writer's Direct Dial Number.
(201-316-7484)
July 17, 1989 C000-89-0676 Mr. Steven A. Varga, Director Division of Reactor Projects I/II U. S. Office of Nuclear Reactor Regulations Nuclear Regulatory Commission Washington, DC 20555 Dear Mr. Vargas Subjects Oyster Creek Nuclear Generating Station (OCNGS)
Docket No. 50-219 Compliance with 10 CFR 50.44 On June 27, 1989, I and other members of my staff met with the NRC to discuss Oyster Creek's compliance with the combustible gas control requirements of 10 CFR 50.44.
The meeting was arranged in responso to NRC letter dated i
May 1, 1989.
The stated purpose of the meeting was to resolve questions of compliance with 10 CFR 50.44.
The letter expressed the staff's intent to either issue a safety evaluation accepting the Oyster Creek design or proposed modifications, or to issue an order requiring compliance with section 50.44.
As you and I agreed, and based on your conversatienc with my staff, I cxpected that, in addition to focusing on the nitrogen inerting system, the staff would explain its views on the technical and legal bases provided by GPU Nuclear for its compliance position.
Since previous meetings had not accomplished resolution, the presence of senior GPU Nuclear and NRC r;.anagement was deemed necessary.
The meeting was not conducted as planned with regard to the level of management in attendance or the agreed upon agenda. More importantly, progress toward resolution of the issue was not accomplished.
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GPU Nuclear Corporation is a subsidiary of General Public Utilities Corporation i
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COMPLIANCE WITH 10 CFR 50.44 July 17, 1989 l
-Page 2 I
I The staff has communicated to us at various meetings that an active repressurization and purge system in addition to the inerted containment is required to satisfy the requirements of 50.44.
Thc staff has not i
however explained the technical need for such a system or the legal basis l
for requiring it.
Unfortunately, the NRC staff at the meeting did not j
I clarify the-basis for the staff's position or explain why GPU Nuclear's compliance position was not technic-?ly and legally acceptable.
The staff's focus at the June 27 meeting was on how GPU Nuclear could increase the reliability of the Oyster Creek nitrogen injection capability by upgrading selected areas of the system.
Oyster Creek has the j
capability to vec.t and purge the conta,iment with air or nitrogen if necessary. However, the systems for this capability are not needed nor used for section 50.44 events, and GPU Nuclear does not take credit for i
l them in its compliance with section 50.44, Nevertheless, as part of the preparation for the meeting, the GPU Nuclear staff addressed the question of whether a repressurization and purge system designed in accordence with the applicable criteria would improve safety at Oyster Creek for events within the scope of 50.44, or for events beyond the scope of 50.44.
Based on Revision 4 of the BWR Emergency Operating Procedure Guidelines, which has been approved by the NRC, a repressurization system would not be utilized.
In addition, venting and purging with nitrogen under post-LOCA conditions would not be attempted because of the prolonged duration to purge the containment of a combustible gas mixtura. Oni;' under an extremely unlikely combination of post-LOCA events beyond the scope of section 50.44, including the unavu11 ability of the higher volume air purge line, would purging with nitrogen be contemplated. Upgrading the current nitrogen injection system would result in an insignificant reduction in risk.
The GPU Nuclear compliance position has been before tre staff for a considerable period of time.
Our compliance position was most recently addressed in our letter of May 31, 1988. That letter also addressed the Lacertainties we perceived in the staff's regulatory and technical bases nor its conclusions. The key points of the GPU Nuclear compliance pouitio,- and our concerns with the staff's views, are set forth in the attachment to this letter.
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-COMPLIANCE WITH 10 CFR 50.44 o
July 17, 1989 Page 3 GPU Nuclear has invested very substantially in modifications to upgrade the safety and reliability of the Oyster Creek Nuclear Generating Station. We have formal processes, including the Inteorated Schedule, for evaluating priorities and allocating resources to those modifications which give substantial improvements to plant safety and reliability.
Careful considerations of further improvements to maintain containment integrity are part of the Individual Plant Examinations and Severe Accident Management program development, which are ongoing. These efforts reqaire the full atte:.cion of both GPU Nuclear and the NRC staf f.
We are confident that we have provided boti the regulatory and technical basis for compliance with section 50.44.
T'!e staf f's May 1 letter raised the potential of an order requiring compliance with section 50.44.
We left the June 27 meeting with the impression that the staff may be interpreting section 50.44 to encompar. events beyond tl.a scope of the regulation as written. We are more than willing to discuss any requirements or concerns you may have for situations beyond the scope of the regulation, and in fact we have done so, but any such concerns clearly should not be the basis for an order requiring compliance with that regulation.
In conducting its review of NEDO-22155, we would hope that (a) the staff will evaluate it against the requirements of 50.44 as it is written, and (b) that we will have the opportunity to respond to any concerns the staff might identify.
It is essential you consider the key points GPU Nuclear has made on this issue and provide to us the technical and regulatory basis for the staff's position.
R (A Robert L. Long Vice President & Director, Planning & Nuclear Safety RLL/crb Attachment cc Regional Administrator Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, FA 19406 l
Resident Inspector Oyster Creek Nuclear Generating Station Mr. Alex Dromerick U.S.
Nuclear Regulatory Commission Mail Station P1-137 Washington, DC 20555 l
U.S. Nuclear Regulatory Commission Attn: Document Control Desk l
Washington, DC 20555
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L COMPLIANCE WITH 10 CFR 50.44-g
- July 17,-19891 ATTACHMENT Oyster Creek's inerted' containment provides a safe and effective means of post-LOCA combustible gas control, and is in full compliance with the requirements of 50.44.
The GPU Nuclear compliance position is relatively
' straightforward and is based on.the. regulation as written.
Section 50.44(g) requires a combu;tible gas' control system designed to meet the requirements'of General Design criteria (GDC) 41, 42 and 43 of Appendix A to Part 50.
Dyster Creek's inerted containment isLin compliance with
' these criteria in all applicable respects.
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The. amount of metal water reaction to be assumed is governed by 50.44(d)(1)'and is approximately 1% for Oyster Creek. Those events which yield this amount of metal-water reaction are considered within the scope of 50.44.
For 50.44 events, the technical basis for the adequacy of the inerted containment for post-LOCA combustible gas control is contained in the BWR Owners Group report, NEDO-22155, " Generation and Mitigation of Combustible Gas Mixtures in Inerted Mark I Containments," along with various GPU Nuclear submittals and presentations showing that Oyster Creek is conservatively bounded by the analysir in the report. NEDO-22155 demonstrates that oxygen concentration are maintained below Regulatory l
Guide 1.7 combustible gas limits withou requiring containment venting, j
containment repressurization or hydrogen recombiners. The methodology, I
which uses a mechanistically derived oxygen generation rate, is consistent i
with the guidance of Regulatory Guide 1.7 in that it calculates the net i
yield of gasses generated.
j Following a LOCA, the inerted containment is isolated. GPU Nuclear has demonstrated, through its response to Generic' letter 84-09, that there are.
j no unacceptable sources of oxygen.
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GPU Nuclear does not understand the NRC staff's position in several
.f respects. First, the staff has stated that 50.44(g) requires an active j
purge /repressurization system in addition to the inerted containment. The staff, however, has not provided an explanation of its regulatory or technical basis for that interpretation, GPU Nuclear does not read ti.st l
I
. requirement in the regulation, nor does the NRC's Office of the General I
Counsel (OGC).
In a letter dated August 31, 1987 to the BWR Owners Group, OGC stated that sections 50.44(g) and 50.44(c)(3)(1) can be satisfied with i
a " technically acceptable inerted containment system."
The staff has l
never questioned the technical acceptability of the Oyster Creek
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containment with respect to the requirement to meet GDC 41, 42 and 43.
Second, the staff stated at the June 27 meeting that technical acceptability will depend on its review of NEDO-22155. The staff has advised GPU Nuclear that the report is acceptable for purposes of t'
compliance with the recombiner rule in section 50.44(c)(3)(ii), but that it has not been reviewed or accepted for purposes of compliance with section 50.44(g).
It is unclear how a technical report can be approved for one aspect of a regulation, but not for another aspect of the same regulation.
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I COMPLIANCE WITH 10 CFR 50.44 July 17, - 1989.
Page 2 Third, although NEDO-22165 was submitted to.the staff'over seven years.
ago, on' June 21, 1982, GPU Nuclear has not been informed'of any problems with referencing it as a basis for compliance with section 50.44(g). At the June 27 meeting, the staff stated that it was in the process of reviewing the report with respect to the Advanced Boiling Water Reactor p
and that it had identified several concerns that may hinder staff acceptance. The concerns were not communicated to GPU Nuclear. GPU Nuclear is aware that the staff previously expressed three concerns with the' report to another Mark I BWR licensee, but those concerns were not presented in any detail and aesmed to relate to events beyond the assumptions required for purposes of section 50.44.
At the June 27 meeting the staff. stated that the amount of metal-water reaction to be assumed ranges from 0 to 75% and is required by the regulation. This is clearly beyond the requirements of 50.44(d)(1) or any other provision of section 50.44.
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