ML20133A311
| ML20133A311 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 12/19/1996 |
| From: | Frizzle C Maine Yankee |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CDF-96-198, MN-96-178, NUDOCS 9612310037 | |
| Download: ML20133A311 (9) | |
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MaineYankee RE L 4 ABL E E L F.C T RICIT Y SINC E 19 72 329 Bath Road Charles D. Frizzle Brunswick, Maine 04011 President and Chief Executive Officer December 19, 1996 (207) 798-4100 MN-96-178 CDF-96-198 i
UNITED STATES NUCLEAR REGULATORY COMMISSION Attention: Document Control Desk Washington, D.C.
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References:
(a)
License No. DPR-36 (Docket No. 50-309)
(b)
MYAPCo Letter to USNRC dated April 22, 1971 i
(c)
USNRC Letter to MYAPCo dated August 9. 1971 (SNM-1258)
(d)
MYAPCo Letter to USNRC dated March 24. 1988. (MN-88-30).
" Technical Specification Proposed Change 138: Fuel Enrichment Limit" (e)
USNRC Letter to MYAPCo dated March 15,1994 " Issuance of Amendment No. 144"
Subject:
Request for Exemption from 10 CFR Part 70.24 Gentlemen:
Pursuant to the requirements set forth in 10CFR50.12.
10CFR70.24(d', and the guidance contained in NRC Regulatory Guide-8.12, Maine Yankee Atomic Power Co. hereby requests an exemption from the requirements'of 10CFR70.24 " Criticality Accident Requirements".
10CFR70.24 requires, in part, a criticality alarm system, and related procedures and drills.
The attachment to this letter contains the exemption request with an evaluation that justifies the exemption.
This requested exemption is similar to the one previously granted within Maine Yankee Atomic Power Company's Special Nuclear i
Material License (SNM-1258) (Reference (c)).
Very truly yours, A
l Charles D. Frizzle President and Chief Executive Officer Attachment c:
Mr. Hubert Miller Mr. Daniel H. Dorman Mr. Patrick J. Dostie I
Mr. Jimi Yerokun 1
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Mr. Uldis Vanags l
9612310037 961219 PDR ADOCK 05000309 l
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ATIACHMENT EXEMP_ TION R QUESI 4
ER0M_10.CERZO.24 J
CRITICALIILHONITORINGXQUIREMENTS 1.
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DESCRIETIOPLOF_ REQUESTED _ EXEMRIION 4
Maine Yankee Atomic Power Co. hereby requests exemption from 10CFR70,24.
j 10CFR70.24(a) which specifies the requirements for a monitoring system that will i
energize clearly audible alarms if an accidental criticality occurs in each area in which special nuclear material (SNM) is handled, used or stored.
Also.
10CFR70.24(a) requires that emergency procedures be maintained for each area in which licensed SNM is handled, used, or stored to ensure that all personnel i
withdraw to an area of safety upon the sounding of the alarm. These procedures must include the conduct of drills to familiarize personnel with the evacuation plan, designation of responsible individuals for determining the cause of the alarm, and placement of radiation survey instruments in accessible locations for use in such an emergency.
3 This exemption would be similar to one previously applied for in Reference (b).
and granted within Maine Yankee's Special Nuclear Materials License No. SNM-1258, 1
Reference (c), which was issued on August 9,1971.
This exemption was not I
explicitly included in the operating license for Maine Yankee.
1 II.
JUSTIEICATION _E0R_ GRANTING _THE_ EXEMETION_ REQUESTS 4
.The specific requirements for granting exemptions from Part 70 regulations are i
set forth in 10CFR70.24(d) and 10CFR70.14(a).
In Section 70.24(d), NRC I
anticipated that. licensees 'may request relief from the requirements of 10CFR70.24(a) by applying for an exemption from section 70.24, in'whole or in 4
a part, if good cause is shown. Maine Yankee believes that good cause exists based upon the positions presented below in the context of the requirements of i
L Under Section 70.14(a), the Commission is authorized to grant an exemption upon a demonstration that the exemption: (A) is authorized by law: (B) will not t
endanger life or property or the common defense or security: and (C) is in-the i
public interest.
The following justification addresses each of these requirements and demonstrates that the Commission should grant the requested j
exemption.
j A.
The_ Exemption _Is_Autbotized_By_ Law The Commission's authority to grant requests for exemptions from its regulations has existed since 1956.
The particular authority to grant
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exemptions from the requirements of Part 70 was codified in 10CFR70.14 in l
1972.
Furthermore, the Commission anticipated this type of exemption request in 10CFR70.24(d).
j B.
The_ Exemption _Will_Not_Enda ngen tife_0r_Eroperty_0r_Ihe_ Common _ Defens e_a nd j
Secutity 4'
An exemption request will not endanger life or property or the common defense and security if it can be shown that the request meets the statutory standard of adequate protection to the health and safety of the public.
Furthermore, to ensure the common defense and security are not Page 1
endangered, diversion of SNM must be shown to be precluded.
In light of i
these standards, we describe below how the use, storage, and handling of SNM at Maine Yankee provides adequate protection to the health and safety of the public, and precludes loss or diversion of SNM.
In particular, we focus on the following points: design, characteristics, and existing accident analyses.
1.
Useaf_SNM SNM at Maine Yankee is principally in the form of nuclear fuel.
However, other quantities of SNM are used (and stored) at Maine Yankee in the form of fissile material incorporated into nuclear instrumentation (wide range logarithymic detectors, in-vessel and ex-vessel flux monitoring capsules), reactor sources. Health Physics sources, and Quality Control radiography sources.
The facilities licensed pursuant to 10 CFR Part 50 are exempt from Section 70.24(b) for SNM "used or to be used in the reactor" pursuant to Section 70.24(c).
Thus the focus of the exemption request is directed toward the requirements of 70.24(a).
The amount of special nuclear material contained in the nuclear instrumentation and reactor sources is small, less than the quantities specified in Section 70.24(a).
The small quantity of special nuclear material present in the nuclear instrumentation and the form in which the special nuclear material is maintained (a very thin coating sprayed on the inside of the sealed fission chamber contained at the end of each monitor) preclude inadvertent criticality.
The amount of special nuclear material contained in the Health Physics and Quality Control sources is also less than an amount that could achieve criticality and less than the amounts specified in 10 CFR 70.24(a).
This special nuclear material is used for Health Physics instrument calibrations and Quality Control industrial radiography. Limits on the quantities of this material will preclude inadvertent criticality.
Inadvertent or accidental criticality in the reactor vessel is precluded through compliance with the facility Technical Specifications which include reactivity control requirements (e.g.,
shutdown margin demonstrations, limits on control rod movements).
l instrumentation requirements (e.g., reactor power and radiation i
monitors), and controls on refueling operations.
In addition, the l
plant operator's continuous attention directed toward instruments monitoring behavior of the nuclear fuel in the reactor assures that the facility is operated in such a manner as to preclude inadvertent criticality.
Finally since access to the fuel in the reactor vessel is not physically possible while in use and is procedurally controlled during refueling, there are no concerns associated with loss or diversion of the fuel.
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Therefore, the requirements of 10 CFR 70.24 are not necessary for special nuclear material in the form of nuclear fuel while used in the reactor vessel or in the form of instrumentation or sources, and thus granting this exemption will not endanger life or property or the common defense and security.
2.
Storagelf_SNM SNM. as nuclear fuel, is stored in either the spent fuel pool or the new fuel storage room.
_The spent fuel pool is used to store irradiated fuel under water after its discharge from the reactor and new fuel prior to loading it into the reactor.
The spent fuel pool is designed to store the fuel in a geometric array that precludes criticality.
In addition, existing Technical Specifications limits on the effective neutron multiplication factor. K r, are maintained less than or equal to 0.95 even with the pool fill'ed with unborated water.
The Maine Yankee spent fuel storage facility, as approved by Reference (e)2. is located within the fuel building and has a total capacity of 2019 fuel assemblies with two separate storage regions.
Region I has a nominal center-to-center spacing between storage cells of 10.5 inches and is designed to accommodate new fuel with a maximum enrichment of 4.5 weight percent (w/o) U-235. or spent fuel regardless of its discharge burnup. Region II has a nominal center-to-center spacing of 9.085 inches and is designed to accommodate fuel assemblies of various initial enrichments that have accumulated i
specified minimum burnups.
The design of the spent fuel storage-racks incorporates Boral as a neutron absorber in the cell walls, thereby allowing for closer, more dense storage of spent fuel.
The storage facility, which contains spent fuel storage racks, is constructed of reinforced concrete with a stainless steel lining and i
is an integral part of the fuel building.
The facility provides a cooling and shielding medium for the spent fuel (borated water) although no credit is taken for the presence of boron in the pool water in meeting the criticality limits.
The pool is designed to safely resist the hypothetical earthquake or tornado, as well as the applied loads of the water and fuel.
The new fuel storage room is designed for the dry storage of 160 fuel assemblies with a minimum center-to-center spacing of 20 inches. The new fuel room floor has two floor' drains which prevent flooding of the new fuel room.
Even though the room is designed to prevent flooding, criticality analyses have been performed to demonstrate that the fuel storage configuration would maintain an effective neutron multiplication factor. K,fr. less than or equal to 0.95. if flooded, and less than or equal to 0.98 with optimum low
' The implementation of Amendment No.144 (Reracking) is currently ongoing.
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density moderation (foam) for fuel enrichments up to 5.5 weight percent (w/o) U-235. The flooded condition is analyzed with unborated water at 68 F. The criticality analysis is described in Reference (d).
l The new fuel storage room can also be used to store limited quantities of special nuclear material other than fuel.
This material may be stored behind a fence, separate from new fuel assemblies. Criticality analyses have been performed to demonstrate that even if a quantity of pure Uranium-235 thirty-five times greater than the quantities'specified in Section 70.24(a) were to be spherically configured and axially centered on the active length of a fuel assembly, the new fuel storage configuration would maintain an effective neutron multiplication factor, K,rr, less than or equal to 0.95, assuming the new fuel storage room is filled with 160 fuel assemblies at an enrichment of 5.0 weight percent Uranium-235.
Special Nuclear Material License No. SNM-1258 (Reference (c)), which was issued for Maine Yankee Atomic Power Co. On August 9,1971, approved an exemption from the provision of 10 CFR 70.24. As part of this special nuclear material license, an additional control for the new fuel storage room was implemented to preclude inadvertent criticality.
Specifically, new fuel assemblies had to be stored in I
such a manner that the polyethylene wrappers would be open at the bottom so that water would drain freely from the assemblies in the l
event of flooding and subsequent draining of the new fuel storage facility.
Procedure 5-64-4 "New Fuel Handling" includes direction to remove the wrapper prior to loading the fuel into the new fuel storage area. No other administrative controls for storage need to be implemented due to the design of the new fuel storage facility and the results of the criticality analysis which concluded that criticality is not possible in the facility.
The presence of an accidental criticality monitoring system would l
not ensure against the loss or diversion of SNM material; consequently, the absence of such a system does not affect the capability of Maine Yankee to ensure SNM is safeguarded.
Therefore, the requirements of Section 70.24 are not necessary for the SNM stored in the ew fuel storage room or spent fuel pool, and j
thus, granting this exemption will not endanger life or property or i
the common defense and security.
3.
Handling _oLSNM New fuel assemblies are delivered by truck to the site in steel containers. The new fuel containers are unloaded and conveyed into the fuel building where the 5-ton crane picks up each fuel assembly, one at a time, and transports it to storage in the new fuel storage racks.
To place an assembly in the pool, the fuel assembly is placed in the fuel elevator by the 5-ton crane. The fuel elevator Page 4
lowers the fuel assembly to the bottom of the fuel pool.
From the i
fuel elevator, the fuel assembly is. moved by the movable platform j
hoist to the fuel assembly upender for transport into -the 1
containment, or into a spent fuel storage location prior to i
transporting it to the upender.
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Unirradiated and irradiated fuel-is moved to and from the reactor i
l vessel and spent fuel pool racks to accommodate ' refueling i
i operations.
In all cases, fuel movements are procedurally i
i controlled and designed to preclude conditions involving criticality concerns.
In addition, the Technical Specifications.specifically address refueling operations and limit the handling of fuel to ensure against an inadvertent criticality and to preclude certain i
movements over the spent fuel pool and the reactor vessel.
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i The likelihood of a fuel handling incident is minimized by i
administrative controls and physical limitations imposed on. fuel handling operations.
All refueling operations are conducted in accordance with prescribed procedures under direct surveillance of a qualified supervisor.
Also. before any refueling operations.
begin verification of complete control element-assembly (CEA) insertion is obtained by tripping each CEA individually to obtain indication of assembly drop and disengagement from the drive train.
Boron concentration in the coolant is raised to the refueling concentration and verified by sampling. The refueling concentration insures that the core is at least five percent-delta k/k subcritical.
The shutdown margin of five percent delta k/k will keep the core substantially subcritical, even if the highest worth
'CEAs were inadvertently withdrawn from the core without compensating i
boron addition.
i As part of the application for a s)ecial nuclear material license.
Reference (b). Maine Yankee descri)ed the physical characteristics of the new and spent fuel building and certain administrative controls. Among these controls was a commitment to handle new fuel j
assemblies individually and allow only one new fuel assembly to be moved at one time. The use of current fuel building equipment will 1
not permit more that one new fuel assembly to be outside the shipping container at a given time which is not in an acceptable J
designed fuel assembly location. Therefore, based on the process for receiving and handling new fuel Maine Yankee does not believe'the restrictions identified in Reference (b) are required.
While movement of nuclear fuel. presents a potential opportunity for its loss or diversion, the existing procedural controls also ensure i
SNM handling is authorized and monitored. Similarly, the absence of an accidental criticality monitoring system does not affect the j
capability of Maine Yankee to ensure SNM is safeguarded.
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d Therefore, the requirements of Section 70.24 are not necessary for the handling of SNM, and thus, granting this exemption will not endanger life or property or the common defense and security.
C.
The_ Exemption _Requestslr_e_In_Thelubli c_ Interest The guidance provided in Section C.1 of Regulatory Guide 8.12.
" Criticality Accident Alarm Systems." Rev. 2 (October 1988) states:
"Section 70.24 of 10CFR Part 70 requires alarm coverage in each area
'in which such licensed special nuclear material is handled, used or stored.... ' whereas paragraph 4.2.1 of the standard states that the need for criticality alarms must be evaluated for such areas.
If such an evaluation does not determine that a potential for criticality exists, as for example where the quantities or form of s)ecial nuclear material make criticality practically impossible or w1ere geometric spacing is used to preclude criticality, such as in some storage spaces for unirradiated nuclear plant fuel, it is appropriate to request an exemption from 70.24."
This language indicates that where a licensee determines that design and/or procedural safeguards ensure against conditions of accidental criticality, compliance with Section 70.24(a) would not serve the i
underlying purpose of the regulation.
As discussed above in Section II.B. the design of and safety analyses for the spent fuel pool and new fuel storage room, as well as the associated procedural control and Technical Specification requirements, ensure that conditions of accidental criticality are precluded.
Therefore, the application of 10CFR70.24 to Maine Yankee Atomic Power Co. would not serve i
and is act necessary to achieve the underlying purpose of this requirement.
The continued maintenance of a criticality accident monitoring system would require a considerable expenditure of resources.
These resource expenditures would include the operation and maintenance of the system for the life of the Maine Yankee plant as well as the planning and conducting of drills specifically designed to respond to a criticality accident that has been shown by analysis not to be credible.
In light of the purpose of an accidental criticality monitoring system, these resources could otherwise be put to better use improving the operation of Maine Yankee.
Therefore. Maine Yankee concludes that compliance with 10CFR70.24 would result in an undue hardship and other resource e.xpenditures that are significantly in excess of those likely contemplated when this regulation was adopted.
We understand that exemptions from the requirements of 10CFR70.24 have been granted under similar circumstances to Part 50 licensees. Therefore, we conclude that since Maine Yankee is similar in all material respects to other facilities granted such an exemption, compliance with 10CFR70.24 would create an undue hardship and other resource expenditures significantly in excess of those incurred by others similarly situated!
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t We also understand that the NRC is considering a rulemaking to make this kind of exemption request unnecessary.
In SECY-96-147. " Planning for Pursuing Regulatory Improvement in the Area of Exem)tions Granted to Regulations", dated July 1,1996, the NRC staff providet plans to identify and prioritize rulemaking actions to reduce the need for exemptions. 'One of the candidate rulemaking actions was for 10CFR70.24 as follows:
"This regulation requires criticality monitors to be used at a facility if certain quantity limits for-special nuclear materials are exceeded.
The staff envisions that the regulatory language could be changed to require cr'ticality monitors for those cases in' i
which an evaluation has determined that a criticality is credible.
The change-is expected to make the rule more performance based for Part 50 licensees, whose fuel handling facilities, equipment, and procedures are designed to prevent inadvertent criticality events."
This rulemaking action, as envisioned by the SECY paper, would make the rule more performance based, less prescriptive and essentially in agreement with this requested exemption.
Continued monitoring based on 10CFR70.24 is unnecessary because of the lack of a credible accident that would produce a criticality.
The burden of criticality monitoring for new and spent fuel would expend Maine Yankee resources that'could be better used to augment the safe operation of the plant in other areas.
Consequently, the exemption request is in the public interest and should be granted pursuant to 10CFR70.14(a).
III. CONCLUSION 1
Because an exemption from the requirements of 10CFR70.24 for Maine Yankee is authorized by law, will not endanger life or property or the common defense and security, is in the public interest, and is requested for good cause, we respectfully submit that, in accordance with the requirements of 10CFR70.14(a) and 70.24(d), the NRC should grant the requested exemption.
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