ML19332C951
| ML19332C951 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 11/16/1989 |
| From: | Sylvia B DETROIT EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML19332C952 | List: |
| References | |
| CON-NRC-89-0215, CON-NRC-89-215 NUDOCS 8911290218 | |
| Download: ML19332C951 (14) | |
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S. Ralph $yld Sernor v4e hepoent
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November 16, 1989 NIC-89-0215 U. S. Welear Regulatory Ccunission Attn Document Control Desk Washington, D. C.
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References:
- 1) Fermi 2 NIC Docket No. 50-341 NIC License No. ifF-43
- 2) Detroit Eison Letter to NIC, NE-89-0209,
" Control Room hergency Filtration System, License condition", dated Septenber 27, 1989
- 3) Detroit Mison letter to NIC, NIC-88-0185,
" Proposed Technical Specification Change (License Amendnent) - Control Room hergency Filtration Systen (3/4.7.2)",
dated Decenber 22, 1988
- 4) Detroit Eison Letter to NBC, EF2-72039,
" Clarification of Position on Silicone Duct Sealant ani Other Issues", dated January 8,1985
Subject:
Proposed Technical Specification Change (License Amendment) - Control Room Dergency Filtration Systen (3/4.7.2) pursuant to 10CFR50.90, Detroit Mison Company hereby proposes to amerd Operating License IFF-43 for the Fermi 2 plant by incorporating the enclosso changes into the Plant Tecialcal Specifications. The proposed changes provide surveillance requirements for periodic leakage testing and visual inspection of the Control Rom Emergency Filtration System to assure the integrity of those portions of the system external to the Control Rom. 'Jhis application for amendment is submitted pursuant to License Condition 2.C(7) of the Fermi 2 Operating License and satisfies the requirements of this License Condition. 'Iherefore, the deletion of License Condition 2.C(7) is
. included in this proposal.
Detroit Mison has evaluatal the proposed Technical Specifications against the criteria of 1GCFR50.92 and determined that no significant hazards consideration is involved. '!he Fermi 2 Chsite Review Organization has approved and the melear Safety Review Group has f001 reviewed the proposed '!%chnical Specifications and concurs with the enclosed determinations. In accordance with 10CFR50.91, Detroit I l Mison has provided a copy of this letter to the State of Michigan.
8911290218 891116
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USIOC November 16, 1989 j
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100-89-0215 Page 2
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If you have any questions, please contet Mr. Glen Ohlemacher at (313)
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596-4275.
Sincerely 1
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Ihclosure ocs A. B. Davis R. W. Defayette W. G. Rogers J. F. Stang.
Supervisor, Advanced Planning and Review Section, Michigan Public Service Cmunission I
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USNRC Novenber 16, 1989 NIC-89-0215 Pge 3 I
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I, B. RhLPH Sn,VIA, do hereby affirm that the foregoing statenents are i
based on facts and circunstances which are true and ecurate to the best of my knowledge and belief.
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E rat #H SYLVIA Senior Vic'e President l
tWAd'L-. 1989, before me i
On this
/b day of personally appeared B. Ralph Syl41a, being first duly sworn and says that he executed the foregoing as his free act and deed.
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Notary Public ROSALIE A ARMETTA Nokry Pubuc. Monroe County. Ml WCommisalonEmpiresJcnit.1992 l.
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NRC-89-0215 Page 1 INTRODUCTION i
During the initial licensing of Fermi 2, cencerns about the use of silicone sealant on duct work in the Control Room Emergency Filtration System (CREFS) outside of the main control room zone were raised by the NRC. The concerns dealt with the ability of the silicone sealant l
to perform its sealing function over the designed plant lifetime of 40 years. The resolution of these concerns, which are discussed in detail in Section 6.4.1 of the Fermi 2 Safety Evaluatioa Report l
(NUREG-0748) Supplements 5 and 6 (SSER 5 and 6), resulted in the issuance of the Fermi 2 Operating License (NPF-43) with Condition 2.C(7).
Condition 2.C(7) reads as follows:
4 (7) Control Room Habitability (Section 6.4.1, SSER #6) 6 Prior to startup following the first refueling outage, DECO shall provide assurance to the NRC staff that potential contamination pathways through those portions of the control room t
air-conditioning system which are external to the control room zone will not have a significant adverse impact on control room habitability, or will propose a technical specification which provides for periodic leakage testing to assure the integrity of those external portions of the control room air-conditioning s
system.
l As discussed in Reference 2, Detroit, Edison has decided to follow the option provided in the License Condition to propose a Technical Specification for periodio leakage testing. This proposal provides the required Technical Specification.
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Enclosure t)
Page 2
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i To provide additional assurance that unexpected degradation of the silicone does not occur between leakage tests, Detroit Edison is
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proposing a surveillance requirement for visual inspection of accessible portions of the ductwork of concern. The proposed surveillance will require an annual inspection to verify that the silicone sealant has not undergone cracking, debonding, or other abnormal degradation.
This proposal satisfies the provisions of License Condition 2.C(7).
I Therefore, deletion of this condition from the license is proposed.
EVALUATION The proposed periodic leakage test surveillance requirement consists of three parts. These are test method, acceptance criteria, and test frequency. Each aspect is evaluated individually below. The proposed visual inspection requirements are evaluated in conjunction with the discussion of the proposed leakage test frequency.
Test Method The proposed duct leakage testing is specified to be performed in accordance with ANSI N510-1980. This document provides the industry standards for the testing of emergency flitration systems at nuclear power plants.
Included are acceptable methods for duct leak testing.
Since ANSI N510-1980 provides the most recent industry standard for testing of the type proposed, Detroit Edison believes it is acceptable-to reference the standard in this surveillance requirement. Further,
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this is consistent with other CREFS surveillance requirements, such as system flow rate verification, which reference ANSI N510-1980.
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I Enclosure to j
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NRC-89-0215 Page 3 1
i The surveillance requirement must also specify the test pressures of concern.
In this case, there are four ducts of concern. Each duct must be tested at two pressures; one pressure represents the maximum negative pressure expected for that duct during normal system operation, the other pressure represents the maximum negative pressure expected for that duct during operation with a single failure of a damper. The single damper failure chosen is the one that results in the greatest negative pressure in all four ducts of concern. These test conditions, rather than the specific pressures for each duct, are listed in the Specification. Specifying that the test pressures be at or more negative than the maximum negative pressure expected for each of the four specific duct sections of concern during normal system operation and during operation with a single damper failure assures that the tests will be conducted at the appropriate pressures while l
eliminating the need for future Technical Specification changes if the normal operating pressure in a specific duct changes over the life of the plant. The calculations performed for test pressures for the first refueling outage are contained in Attachment 1.
i Acceptance Criteria Leakage into the subject ducts would provide a path of unfiltered air L
inleakage into the Control Room. Currently, the calculations for radiological dose to Control Room personnel assume a 10 standard cubic foot per minute (sofa) inleakage from all sources averaged over the 30-day period. This calculation, as documented in Section 6.4.1 of SSERS, resulted in a dose of 16.1 ren to the thyroid, which is well below the criteria of General Design Criteria (GDC) 19 of 10CFR50 Appendix A.
The GDC 19 criteria is 5 rem whole body exposure or the equivalent. The NRC Standard Review Plan (NUREG-0800' Section 6.4
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Enclo;ure to NRO-89-0215-l Page 4 i
i provides 30 ren thyroid dose as a standard for meeting the GDC 19 j
criteria.
To support the establishment of appropriate acceptance criteria for this surveillance requirement, Detroit Edison has recalculated the dose to the Control Room personnel based upon new unfiltered air inleakage assumptions. The same methodology and other assumptions i
used by the NRC staff in the pre-operating license review were used in these calculations, with the exception of the dose conversion factors for iodine. The more recently established values were used, which are contained in Regulatory Guide 1.109, Revision 1, October 1977.
Details on the dose calculation are found in the attached Design Calculation 5107 (Attachment 2).
In addition to unfiltered inleakage due to duct leakage, unfiltered air may enter the Control Room due to the openings of Control Room doors for ingress and egress during the 30-day period. The Fermi 2 l
Control Room has vestibules installed in the doorways which are used for normal ingress and egress. Although other doors penetrate the Control Room envelope, these doors would not normally be used under accident conditions. Detroit Edison has determined that a leakage of 1.0 scfm averaged over the 30-day period can be conservatively assigned to the opening of Control Room access doors. This is based upon calculations of air exchange during periodic use of the doors.
The Fermi 2 CREFS consists of redundant, divisional, fans and dampers
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and non-redundant passive flow paths. The failure of a damper can 2
L cause significantly increased negative pressures in the subject ductwork. However, this occurrence will be readily detected by the Control Room operator from Control Room indication and alarms. For this reason, the duration of CREFS operation in this " failure mode" is 1
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Enclosure to i
NRC-89-0215 Page 5
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limited to 30 minutes.
At that time it is assumed that the operator shifts to the operable division of the CREFS. The calculations performed assume the single damper failure occurs at the worst point-in the scenario, which is at the time of accident initiation.
The Fermi 2 accident analysis, in general, allows credit to be taken for operator action following time periods ranging from 10 minutes to 30 minutes. For' conservatism, 30 minutes is designated as the time required for the operator to d9tect the damper failure and shift CREFS operation to the unaffected division of active components.
The revised control room dose calculations, which include the I
calculations for in-leakage for doors as well as for duct in-leakage, are attached as Attachment 2.
The assumed combined inleakage for the four ducts under both the normal and failure modes of CREFS operation correspond to the acceptance criteria for the proposed leakage testing.
Test Frequency i
Detroit Edison is proposing that this duct leakage testing be performed at least once per 36 months. This interval corresponds to every second refueling outage.
In Reference 4, Detroit Edison provided the NRC staff with information concerning the properties of silicone sealant. This information 0
included that silicone sealant has an expected 40-year life at 202 F 7 rad environments. The and that the sealant is qualified for 1x10 temperature and radiation levels at Fermi 2 for this application are well below these levels.
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Enclosure t)
Page 6 i
In addition, two sections of the ductwork of concern were leak tested per ANSI N510-1980 in August 1984. The results, when compared to similar tests performed recently in October 1989, shows that the leakage characteristics of the ducts have not significantly changed in the intervening 62 months.
1 The above information indicates that, once tested, the ductwork and the associated sealant should be expected to maintain their integrity I
for the proposed 36 month surveillance test interval. However; the concern that, once the sealant reaches its end of life, the material will rapidly deteriorate must be addressed.
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Firstly, the duct longitudina) seams in question were braze welded
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prior to the application of the sealant. Thus, the sealant acts as a backup to the weld and if the sealant completely failed the leakage characteristics of the ductwork is not expected to be appreciably changed. 'However, since the application of sealant was an accepted construction practice at the time of Fermi 2's corstruction, the ducts were never leak tested without the sealant applied. Consequently, the effect of complete sealant failure cannot be quantified.
I For this reason, Detroit Edison is proposing an additional visual inspection program (Surveillance Requirement 4.7.2.2) for the silicone sealant on the ductwork of concern which is accessible during normal l
plant operation. This sealant will be visually inspected for deterioration annually. Since the accessible seams are representative of all the seams of concern (the environment of all seams is the same), the additional inspections will provide additional assurance that an onset of general deterioration of the silicone sealant between tests does not go undetected.
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Enclosure to NRC-89-0215-1 Page 7 Since the appropriate course of action for a finding from these visual inspections depends on the nature of the finding, the proposed
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surveillance requires that the intended course of action be provided to the NRC staff in a Special Report within 111 days of the finding.
The nature of the finding could require a more prompt reporting requireaent to be invoked, and any actions necessary to assure safe l
plant operation will be taken regardless of the time frame for the j
Special Report.
i Finally; if, notwithstanding the above, the leakage characteristics of the ductwork of concern were to deteriorate the following conservatisms exist to mitigate the consequencest 1)
The ductwork of concern is located in the enclosed Auxiliary l
Building and is therefore not directly in the radioactive plume created by the accident scenario.
(See Figure 1) 2)
Some portions of the ductwork do not experience negative pressures unless significant filter loading occurs. This condition is not expected to occur.
3)
There exists a aargin of 11 3 rem to the thyroid between the results of the new Control Room dose calculation (18.7 rem thyroid) and the GDC 19 criteria (30 rem thyroid).
For these reasons, Detroit Edison believes the prcposed surveillance P
intervals to be acceptable.
Enclosure to NRC-89-0215 Page 8 SIGNIFICANT HAZARDS ODIISIDERATION i
In accordance with 10CFR50 92, Detroit Edison has made a determination j
that the proposed amendment involves no significant har.ards considerations. To make this determination, Detroit Edison must f
f establish that operation in accordance with the proposed amendment would not
- 1) involve a significant increase in the probability or consequences of an accident previously evaluated, or 2) create the possibility of a new or different kind of accident from any accident previously evaluated, or 3) involve a significant reduction in a t
margin of safety.
The proposed change to include surveillance requirements to assure the integrity of those portions of the Control Room Emergency Filtration l
System (CREFS) external to the Control Room does not
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1)
Involve a significant increase in the probability or consequences of an accident previously evaluated. The new surveillance requirements act to give assurance that the radiation dose to Control Room personnel is maintained below the criteria of General Design Criteria (GDC) 19 of 10CFR50 Appendix A as previously evaluated. As such, the change acts to ensure that-the consequences of previously evaluated accidents remain as 1
evaluated. The CREFS is not associated with any accident initiating mechanism; therefore, the probability of ar.?
previously evaluated accident is unchanged.
2)
Create the possibility of a new or different kind of accident from any accident previously evaluated. The change provides verification that passive features of the CREFS are not degrading. The proposed leakage test must be performed when the
Enclosura to NRC-89-0215 Page 9 j
i ductwork to be tested is permitted by the Technical Specifications to be out-of-service, or the ACTION statement for i
CREFS will apply. Therefore, the test does not affect the ability of the CREFS to operate in the normal or emergency mode when required. Conduct of the proposed inspections does not affect the normal or emergency modes of CREFS operation. The i
proposal does not result in any modification of sys'am or plant i
design. Therefore, the proposal does not create any new accident initiating mechanisms.
3)
Involve a significant reduction in a margin of safety. The change assures that the radiation dose to Control Room personnel during accident conditions remain below CDC 19 criteria over the plant lifetime.
In so doing, the change acts to maintain the t
margin of safety, Based on the above, Detroit Edison has determined that the proposed amendment does not involve a significant hazards consideration.
l ENVIROIDG3fTAL INPACT Detroit Edison has reviewed the proposed Technical Specification j-l changes against the criteria of 10CFR51.22 for environmental considerations. The proposed change does not involve a significant hazards consideration, nor significantly change the types or significantly increase the amounts of effluents that may be released offsite, nor significantly increase individual or curulative i
occupational radiation exposures. Based on the foregoing, Detroit Edison concludes that the proposed Technical Specifications do meet the criteria given in 10CFR51.22(c)(9) for a categorical exclusion from the requirements for an Environmental Impact Statement.
Enc 1:sure t3 4
NRC-89-0215 Page 10 00NCLUSION In Reference 3, Detroit Edison submitted a proposal to change the CREFS Technical Specification to aake improvements in usability and l
clarity. The attached proposed Technical Specification change is I
based upon the current Fermi 2 Technical Specifications. The proposed Technical Specification changes for the Reference 3 proposal which j
includes the provisions of this proposal are also attached.
Based on the evaluation above
- 1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and 2) such activities will be conducted in compliance with the Commission's regulations and p"oposed amendments will not be inimical to the common defense and security or to the health and safety of the public.
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