NRC-98-0012, Comment Opposing Proposed Rule 10CFR50 & 70 Re Exemption from Criticality Accident Requirements. Detroit Edison Concerned That Proposed Changes Will Not Provide Sufficient Flexibility Meeting Regulations to Criticality Monitoring
| ML20198Q640 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 01/02/1998 |
| From: | Peterson N DETROIT EDISON CO. |
| To: | NRC OFFICE OF THE SECRETARY (SECY) |
| References | |
| CON-NRC-98-0012, CON-NRC-98-12, FRN-62FR63825, FRN-62FR63911, RULE-PR-50, RULE-PR-70 62FR63825-00007, 62FR63825-7, TAC-M96177, NUDOCS 9801230105 | |
| Download: ML20198Q640 (4) | |
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O-January 2,1998 NRC-98 0012 DOCKET NUhf8ERna 0# 7O PROPOSED RULE rn 3 Secretary
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U. S. Nuclear Regulatory Commission (G 2 A4 G39 it)
Washington D. C. 20555-0001 Attention: Rulemaking and Adjudications Staff
References:
1)
Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43 2)
NRC Letter dated October 31,1997 " Exemption From Criticality Accident Requirements in 10 CFR 70.24(a) Grand Gulf Nuclear Station, Unit 1 (TAC NO. M96177)"
Subject:
Detroit Edison Comments on the Proposed and Direct Final Rulemaking on Criticality Accident Requirements,10CFR Parts 50.68 and 70.24 (62 FR 63825 and 6391 h On December 3,1997, the Nuclear Regulatory Commission (NRC) issued a proposed and direct fmal rule with opportunity to comment on Criticality Accident Requirements (62 FR 63825 and 63911). The purpose of this letter is to submit Detroit Edison's comments on the above rules.
The enclosure to this letter provides Detroit Edison's comments on the above subject rules. Detroit Edison is concerned that the proposed changes will not provide sufficient flexibility in meeting the regulations relating to criticality monitoring and will require Detroit Edison to request an exemption from the rules unless the
. comments are satisfactorily resolved and/or incorporated in the final rule pior to its proposed effective date of February 17,1998.
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USNRC NRC 98 0012 Page 2 If you should have any questions concerning Detroit Edison's comments please contact liari O. Arora, Principal Licensing Engineer, at (313 or 734) 586 4213.
Sincerely, Norman K. Peterson Director, Nuclear Licensing Enclosure cc: K. Cozens (NEI)
D. J. Modeen (NEI)
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Enclosure to NRC 98 0012 Page1 Comments'en Final Rulemaking on Criticality Accident Requirements; 10CFR 50.68 and 70.24 y
10 CFR 50.68(bM3)
The requirement for Keff<0.98 with optimum moderation of fresh fuel of maximum; permissible U 235 enrichment loaded in the new fuel storage racks filled with low-
- density hydrogenous fluid cannot be met at some Boiling Water Reactors (BWRs).
General Electric (GE) dealt with this issue over 20 years ago, and concluded that there is an extremely remote possibility for inadvertently establishing critical conditions in the new fuel storage racks, or in a dry spent fuel pool loaded with new fuel.
An analysis by GE indicated that it would require the introduction of a low equivalent water density material to completely occupy the space in and around an array of fuel assemblies in storage for the occurrence of a criticality. Both 10x25 and 20x25 bundle arrays were analyzed, wPh and without gadolinia, to simulate reactivity conditions from -
initial core loads to the nost reactive design basis reload fuel (as of 1976). In all cases, the optimum moderatio i occurred when th.: equivalent water density was approximately equal to 0.2 gram /cc. In the worst cas, a range of equivalent water densities from 0.05 to 0.45 grams /cc was undesirable in conit. ming to the 0.98 Keff design basis limit.
In the interest of assuring safety margins in the areas where fuel is handled, additional -
controls that further reduce the probability of a criticality occurrence were recommended by_GE to their customers in Service Information Letter (SIL) 152 " Criticality Margins for Storage of New Fuel," dated March 31,1976. In summary, the SIL recommends actions for keeping the new fuel storage vault dry (drains open, no fire protection fogging nozzles in the area etc.).
Detroit Edison believes that criticality in the new fuel storage racks is not a credible event
. provided utilities followed the guidance given in SIL 152 and the criteria in 10 CFR 50.68(b)(3) should be revised to include exemption from the requirements if administrative controls preclude optimum moderation conditions.
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Enclosure to NRC-98 0012 Page 2 10 CFR 50.68(b)(6)
The NRC needs to define " Fuel Handling," and " Storage and Associated Handling Areas." This section requires that General Design Criteria (GDC) 63 be met. However, GDC 63 only addresses monitoring of the fuel storage and associated handling areas in terms of being in reactor refr-ling areas, and does not address the case v> hen the fuel is unloaded at another location. This needs to be clarified whether this is only a requirement during fuel assembly movement er ifit applies to movement ofinner metal containers without the outer container.
The proposed changes to 10 CFR 50.68 do not address the recent issue that the GE inner RA3 metal container by itselfis not considered to be an approved shipping container per 10 CFR 71, and therefore, the handling of the inner metal container without the outer wooden overpack falls under the 10 CFR 70.24 requirements, The proposed (10CFR 50.68 (b) (6)) rule does not clearly address the concem whether an approved shipping container (per 10 CFR 71) is required to prevent a criticality event, it is Detroit Edison's understanding that the inner container provides sufficient criticality protection. This agrees with the NRC statement as stated in an NRC grant of exemption (Reference 2) for Grand Gulfs 10 CFR 70.24 exemption request. In this grant of exemption, the NRC stated,"It is the inner metal container that ensures that a geometrica!!y safe configuration of the fuel is maintained during transport, handling, storage, and accident conditions, and that the introduction of any moderating agents to the fuel is precluded due to its leak tight construction."
We suggest revising 10 CFR 50.68 (b)(6) to read, ".. associated handling areas when fuel assemblies are removed from the approved metal containers per 10 CFR 71 to detect..."
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