ML20056C500
| ML20056C500 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 08/31/1992 |
| From: | Zuber N Advisory Committee on Reactor Safeguards |
| To: | Catton I Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-CT-2040, CT-2040, NUDOCS 9306240281 | |
| Download: ML20056C500 (5) | |
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August 31, 1992 1
MDORANDEM 'IO:
I. Catton, Chairman, Thermal-Hydraulic Phenomena Subccanittee FROM:
N.' Zuber, ACRS Consultant i
SUBJECT:
ACRS Thermal-Hydraulic Phenomena Subccanittee Meeting:
GE Generic Power Uprate Program / Fermi Unit 2 Power Increase August 18, 1992, Bethesda, Maryland This memorandum presents my comments and reccanendations concerning the General-Electric (GE) generic power uprate prcgram and the proposed 5% power increase:
for Fermi-2.
It is organized in two sections: Section A addresses the power uprater Section B deals with the generic problem of code documentation.-
A.
Power Uprate Fu,-~ -- i by GEl/IEco Ccanents In my memorandum of April 7, 1992, I noted four concerns related to GE/
I DECO presentations of March 26, 1992. These concerns'have been addressed I
in a satisfactory manner at the present (August 18,.1992) meeting.
Specifically:
1 Effeet of Radial Power Profile on Spray Penetration Although calculations.have not been performed with the TRAC-3-D code to determine the effect of a flatter power profile on spray-J 3 g(){ _ penetration, I accept GE's. position that these calculations are.
i not needed (foria 5% power increase) because the'ECC system.has sufficient safety _ margin to acu-. Mate an increase of 15%.
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August 31, 1992 fl. Zuber to I. Catton ACRS T-H Subconmittee Meeting, 8/18/92 A. Power Ucrate Proposed by GE/ DECO, Continued
- 2. Core Power Stability I agree with fiRR's position that the stability problem should be addressed and resolved as a generic issue, and not in the context of a 5% power increase.
I understand that the power / flow stabili-ty problem will be the topic of the T-H Suhr=nittee meeting in September.
- 3. Steam Flow and Heat Balance Calculations At the March 26 meeting, GE's discussion of steam flow and heat balance calculations was not very clear. The explanation provi-ded at the August 18 meeting was both clear and satisfactory.
- 4. Core Water Invel Calculations of feed water transients discussed by GE at the March' meeting indicated a large (5 feet) decrease of water level in the vessel. This was of some concern because it did not seem to be a realistic value.
In addressing this concern, GE noted that the results presented-in March were erroneous. ! Jew calculations performed for Fermi-2 indicate a level decrease of only one foot. I find this new value realistic and acceptable.
August 31, 1992 N. Zuber to I. Catton ACRS T-H Subcountittee Meeting, 8/18/92 A. Power Uprate Promsed by GE/ DECO, Continued Conclusions and Recmmendations
-The concerns and questions raised during the two meetings (Mardt 26, 1992 and August 18, 1992) were addressed by GE/ DECO and by the staff in a pro-fessional and satisfactory manner.
I found their responsiveness and co-operative spirit nest gratifying.
-The program was well organized and managed by both parties, that is, by the industry and by the staff.
-The requested 5% power uprate is well within safety margins available in present plants. It is also within the " noise" level of computer code capa-bilities.
Consequently, it is my judgement that 1.
GE's generic power uprate program should be app'toved, and 2.
Fermi-2 should be granted the requested 5% power increase.
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August 31, 1992 N. Zuber to I. Catton ACRS T-H Subcomittee Meeting, 8/18/92
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i B. Availability of Cbde humorttatie During the meeting GE mentioned calculations performed with a computer code:
(SHEX) with which I was not familiar. Although these calculations were only peripheral to the main topic of the meeting, I am taking this opportunity to address briefly the problem of code documentation, inasmuch as it is a generic issue.
Comments and Reconmendations Thermal-Hydraulic and severe accident' issues are most often addressed'and' resolved by means'of computer code calculations.. Frequently, the results of
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- 1) The reports have not been written (or updated) and/or
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- 2) The reports are proprietary.
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~Thus, any judgements made at the tine of the meeting must'in large part be.
based upon belief and. faith, rather than on documented facts and evidence,.
and a sound technical review and assessment of the results cannot.be made.
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-1 It is true that' the appropriate code documents are eventually _made available to the ACRS. However, the. time which elapses between the' initial' discussion and access to.' supporting code documentation sometimes amounts.to many. nonths.
At_'best, such' delays are counterproductive to a timely, efficient, and. sound technical review process.
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August 31, 1992 N. Zuber to I. Catten ACRS T-H Subcommittee Meeting, 8/18/92 B. Availability of Code Documentation, Continued Coments and Recomendations, Cont'd.
Consequently, I would recommend that whenever the industry and/or staff pre-sent and discuss the results of calculations performed by a computer code, they should make available to the ACRS the documents which descrite the par-ticular version of the code. This should be done before or at the time of the presentation.
I realize that code developers and managers will find this recmmendation-distressful and will, therefore, find numerous reasons to oppose it. How-ever, I believe that in a regulatory agency, technical issues nust be ad-dressed and resolved in a traceable and accountable manner.
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