ML20199J355
| ML20199J355 | |
| Person / Time | |
|---|---|
| Site: | 07000036 |
| Issue date: | 01/30/1998 |
| From: | Sharkey R ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY, ASEA BROWN BOVERI, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| TAC-L30975, NUDOCS 9802050291 | |
| Download: ML20199J355 (35) | |
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ABB Docket No. 70-36 License No. SNM 33 Director, Office of Nuclear hiaterial Safety and Safeguards U.S. Nuclear Regulatory Commission A'ITN: Document Control Desk Washington, DC 20555-0001
Subject:
Request for Additional information, Chapter 4 Criticality Safety (TAC No. L30975)
Dear Dr. Soong:
Combustion lingineering hereby submits the additional infbrmation requested by your letter dated November 3,1997 concerning our application n; questing the revision of Chapter 4 of our license. Chang:s have been made to the April 17,1997 version as indicated in the responses to your questions and the entire Chapter 4 is resubmitted with a current date. The changes originally made to Chapter 4 in this amendment request were identified in the first phase of our Criticality Safety Program Update (CSPU) and were administrative in nature (designed to improve the readability of this chapter). We anticipate that additional changes will be necessary as the CSPU progresses. Thus, as we have indicated in our response to some of your questions, additional changes that were beyond the scope of our first submission will be addressed in future submittals.
If there are questions regarding this matter, please feel free to contact Mr. Ilal liskridge of my stalTat (314) 937-4691 lixt. 319 or myself at (314) 937 4691 lixt. 399.
Sincerely, COMBUSTION liNGINiiliRING, INC.
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v bMN Robert W. Sharkey Director, Regulatory Affairs Date f
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raw 680 linclosures:
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4 Enclosure I to RA98/680 Reply to Request for AdditionalInfbrmation Application Dated April 17,1997 Combustion Engineering,Inc.
Docket 70 36 Technical Quentions:
1.
In Chapter.t, provide a list of all critical;ty safety controls used at the site and their definitions (e.g.,
favorable geometry (which should ahvays be used in conjunction with another control), geometry 1
control, volume control, fixed neutron absorber, neutron absorbing additives, coticentration control of uranium, concentration control of moderators, mass control of uranium, mass control of moderators, process parameter contro!, control of array size, control of spacing fiom other fissile units, neutron interaction, reDection, etc.).
Chapter 4 discusses criticality safety controls used at Hematite. A list and definitions of criticality safety controls will be incorporated into a subsequent amendment request.
2.
Deline and explain the following types of conditions during processing operations: operating, normal, credible abnormal, accident, normal operating, and credible abnormal operating.
Operating, normali and normal operating are used interchangeably to describe processes or equipment operating within the design parameters for routine operation. Accident, credible abnormal, and credible abnormal operating are used interchangeably to denote off normal conditions for which there is a credible pathway.
3.
Three times you mention tb9t the ".. highest effective multiplication factor for nonnal or credible abnormal operating conditions shall be less than or equal to 0.95 including applicable biases and calculational uncertainties."
(a)
Explain why this is repeated in different places.
This is repeated for emphasis.
(b)
What is the justification for both the normal and credible abnonnal condition limits to be the same?
The limits are the same, both for ease of analysis and to take a conservative approach.
(c)
Why is there no multiplication factor limit (br aceident conditions?
Single contingency accident conditions have the same conservative multiplication factor limits as credible abnormal an6 credible abnormal operating conditions. See the answer
-to question two.
4 (d)
- What is the multiplication factor limit for accident conditions?
Yhe limit is 0.95. as stated above.
(c) llow were the limits for nonnal, credible abnormal, and accident conditions detennined?
The limit of 0.95 was arbitrarily selected as a very conservative limit value.
-4.
In Section 4.1.1 (b),
(a)-
The purpose of controls is to conduct safe operations. Change " achieve process throughput" to
" achieve safe operations."
l The phrase " achieve process throughput"in the context of Section 4.1.1 (b) refers to the reason favorable geometry contro's are not used for all processes and in no way implies that controls are not needed to conduct safe operations. To clarify, the phrase has been changed as suggested.
(b)
All three methods of communication (postings, operating procedures, and training) should be used to communicate infonnation to workers. Change " Procedures, or training" to " procedures,
_ and training."
Communications specifically refers to controlled parameters and their limits in cases when favorable geometry controls are not used. Postings contain controlled parameters and their limits when operators can monitor or affect those controlled parameters in the course of their duties. However, changing the "or" to an "and"in the sentence would require that all controls and limits be included in postings and would needlessly
[
complicate the postings. We believe that the current wording is appropriate.
5.
In Section 4.1.1 (c)
Credible abnormal conditions are likely to be encountered in a process. Thus, add " credible abnormal"
- conditions to the list of conditions under which the entire process will be suberitical.
This change has been made.
6.
In Section 4.1.3, Criticality safety evaluations should include all the relevant conditions in a process. Thus, add "nonnal b
and abnormal conditions" to the scenarios considered in the evaluation of nuclear criticality safety.
This is already included in " potential" scenarios.
2 r
4 7.
In Section 4.1.6, (a) lixplain why you renmved the restriction against intermixing empty and loaded containers.
This was considered to be unnecessary redundant control. Unmarked empty containers in an array are considered to be full.
(b) lixplain u hy empty containers should be allowed to be unsigned in non " empty container" areas.
Empty containers considered full and stored in accordance with procedures and postings governing the storage area obviously have no safety significance, signed or not.
However, empty containers are required by Section 4.1.6 to be so labeled unless they are in an area designated for storage of empty containers or the) are uncovered and therefore obviously empty of SNM. " Empty containers shall be labeled accordingly or placed in designated areas" has been reworded to state " Empty containers shall be labeled accordingly or placed in areas designated for the storage of empty containers" to clarify this requirement.
(c) lixplain why unsigned empty containers should be allowed to be uncovered.
Section 4.1.6 states:" Uncovered empty containers do not require an empty sign." An empty t.ign is not required because they can easily be verified as being empty.
I 8.
Section 4.1.7 does not include the description of how "Preoperational Testing" will be pertermed.
Modify the section to include it.
Section 4.1.7 states, "Preoperational testing and inspection shall be performed as described in Chapter 2, Section 2.7." Section 2.7 states, "If it is deemed necessary, by any reviewer, that an inspection of equipment, procedures. and postings to assure completeness prior to startup J
of a new or modified procet s, the requirement for such an inspection will be so designated in the Change Request. Such inspections shall be documented as part of the records for this facility change." Details ofinspection and any associated preoperational testing are very process or equipment dependent and are therefore best left to the specific evaluation. The implementing procedure for nuclear criticality safety evaluations requires a sign-off sheet containing the preoperational requirements to be prepared and transmitted to the person responsible for management of the change being processed.
9.
In Section 4.2.1.2, (a)
Provide a list and description of all multiparameter controls that are used at the site.
Parameters being controlled for processes at the site are listed in Table 4-4. In addition, administrative controls may be applied.
3 m
(b)
Explain what is meant by "or defined configurations ofindividual SNM units in a given process layout."
Defined configurations are the physicallayout, dimensions and spacing that are established for each operation during the analysis and evaluation.
(c)
Confirm that the term " nuclear safety analysis" includes both " criticality safety" and "' radiation protection",
it does not. Chapter 4 addresses only nuclear criticality safety. Radiation protection analysis is included in the change management process and is performed per requirements of Chapters 2 & 3 of the license. The term " nuclear safety" has been changed to " criticality safety" for clarification.
(d)
Deline and explain the term " safe unit."
" Safe units" mentioned in Section 4.2.1.2 are uranium concentration control safe units which are limited to a maximum of 25 grams of uranium per liter. The concept is similar to that cf a safe individual unit (SIU), discussed in,"
",n 4.2.1.1, without the requirement that the units be isolated from one ar Throughout the remainder of the chapter, " safe unit"is used synonymously w'
. or to indicate one unit of an array of SIUs.
10.
In Section 4.2.1.3 (e),
Justify why you remov.d the statement identifying that a program to periodically verify the presence of the parasitic isotopes would be maintained or reinstate this statement.
The statement referred specifically to the parasitic isotopes in enhanced structural parasitics.
This requirement was replaced by the broader requirement that the NCSE " consider the possibility of depletion of the parasitic isotope (s)in structural or fixed neutron absorbers."
" Consider" has been changed to " address" to clarify the intent of this change, which is more conservative.
I1.
In Section 4.2.1.3 (f),
(a)
Explain how maintaining structural integrity of this structure is included in the criticality safety evaluation.
Structural integrity is verified during construction and is normally not expected to change.
When necessary, maintenance of structuralintegrity is addressed in the NCSE. The requirements are specific to the unit beit.g evaluated
+= = = = =
4 n
(b) llow will the confirmation of the structural integrity be perfonned over time?
There is no specific program addressing structural integrity unless specified by a specific NCSE. We believe that any other structural degradation would be discovered in the normal course of operations.
12.
In Section 4.2.1.3 (1),
lixplain which " geometry" control fbr criticality safety is being used.
Any geometry control, including spacing, dimensions, !ayout or configuration.
13 in Section 4.2.1.3 (m),
lixplain how "less than full neutron reflection" could be considered a control for criticality safety, in some cases, the design of the equipment provides a limit either on the thleitness of the reflector or on the proximity of the reflector to the vessel containing SNM. In theae cases, the reactivity is reduced when compared to a tightly fitting, one foot thick water reflector (full reflection).
14.
In Section 4.2.2.1 (g),
Itevise to include that the criticality safety evaluation should show that the transit is safe before the transit is begun.
The sentence has been revised from, " Safe units in transit shall not be permitted to enter an exclusion area unless a criticality safety evaluation has been performed for such transit" to
" Safe units in transit shall not be permitted to enter an exclusion area unless a criticality safety evaluation has shown the transit to be safe."
15, in Section 4,.t.1 (i),
lixplain the sources and validation for the numerical values in this subpart.
A pellet pan of known weight and volume was filled successively with randomly stacked pellets and the weight was measured. See Chapter 14, Section 14.3.3.5 of this license, i
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==
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16.
In Section 4.2.2.1 (j),
Define and explain the phrase " include the double batch allowance."
The allowance for double batching nas been included in the values in Table 41, Part B. These values have been reduced from the minimum critical mass of UO by a factor of 2.3 (see 2
Section 4.2.1.1). If a second mass in the amount listed in Table 4-1, Pan B is then inadvertently transferred to a mass limited vessel (double batching), an adeciuate safety margin
- remains, 17.
In Section 4.2.2.1 (k),
Justify why you removed the restriction on the use of 927 containers in the Transportation Index of 100 or reinstate this statement.
Arrays of only 927A1 and 927C1 shipping packages, v> hen stacked no more than three high, have no array size limitations (Chapter 4, Secticn 4.2.4 (s), Chapter 13, Section 15.6.8). When in combination with other types of shipping packages, the more restrictive limit of a Tl of 100 is applied to the mixed array. Section 4.2.4 (s) states, " Feel assembly shipping containers other than the 927A1 and 927C1 containers, shall be stored in an array size not exceeding a total transportation index (TI) of one hundred." This phrasing was intended to indicate that 927A1 and 927C1 containers are not restricted to storage in arrays with a Tl of one hundred since, when stacked no more than three high, they are analyzed to be safe in an array with no horizontal array size limitation (Chapter 4, Section 4.2.4 (t)).
I 8.
In Section 4.2.4 (b),
Change "can be continued" to "may be continued."
- We want the evaluation done and the cause of the alarm corrected before the operation is allowed to continue. Section 4.2.4 (b) has been changed to reflect this.
19.
-in Section 4.' 4 (j),
Define " fraction" in the phrase " fraction of the calculated critical mass." Provide the basis for this value, it means less than a safe mass as listed in Tab!e 4.1, Part A. Section 4.2.4(j) has been revised to clarify.
20.
In Section 4.2.4 (o),
Confinn tha* a specific ciiticality safety evaluation is more limiting than the criticality safety evaluation performed for Table 41 Part A.
It is lot necessarily more limiting. This was discussed and resolved during the NRC's November 12 - 13,1997 visit to the Hematite site.
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0 21.
In Section 4,2.4 (u).
Confinn that the respective barrier completely surrounds each Receiver.
It does not, but it does exist where the unit is accessible by personnel. Subsequent evaluations
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have shown that no barrier is needed to enstare the criticality safety of the vessel. A future amendment will discuss the evaluations and request the removal of license restrictions.
22.
In Section 4.2.4 (v),
(a)
Confinn that the system involved is the reactor gas filtration system.
it is the reactor gas filtration system.
(b)
Confirm that the barrier completely surrounds the system.
It does not, but it does exist where the units are accessible by personnel. See response to Question 21.
23.
In Table 4-4, (a)
I' lease explain why all processes do not have two criticality safety contro.ls in order to meet the double contingency principle. Provide the names of the two controls for each process.
Table 4-4 is a listing of controlled parameters, not controls. The title of the table has been changed for clarification. Where only one parameter is identified at least two controls are provided for that parameter, (b)-
lixplain which " geometry" control for criticality safety is being used.
The parameter being controlled is either a Table 4-1 Safe Unit limit or an analyzed config" ration.
ClariMin/ Consistency Questions:
~ 24.
- ne " Table of Contents" for 1.icense SNM 33 should reflect the changes made in Chapter 4.
The Table of Contents will be revised and included with a subsequent revision.
25.
"linclosure I to RA565" dated April 17,1997, should reflect the correct infunnation in the ' Delete Page" Section.
This has been revised to show the correct information.
7
9 26.
In Table 4 1, Part II, Confirm that Note 3 should be changed to iefer to a definition in part (i)in Section 4.2.2.1.
Confirmed. This ge has been made.
27.
It appears that the o 'er and content of the sections in L nter 4 should be reorganized (e.g., Section 4.2.1.3 includes item. a no apparent order; Section 4.2.2.1 includes items that are unrelated to spacing; and Section 4.2.2 includes general and specili, items intermixed in no apparent order).
This will be addressed in a future revision.
28.
It appears that introductory paragraphs to describe the purpose of new sections are missing from certain sections (e.g., Section 4.2.1. 4.2.3,4.2.3.1,4.2.3.2, and 4.2.4).
This will be considered in future amendments.
29, lie consistent in your reference to other sections of the license (i.e., Chapter 2, Section 2.1 or Chapter 4 Section 4.2.3.2).
i The reference stated depends on the level of reference intended, i.e., whether the entire chapter, specific section or subsection is appropriate.
30.
lie consistent in your use of position titles in the license. They should be capitalized (e.g., " Nuclear Criticality Specialist" and "llealth Physics Technicians").
The position titles have been capitalized for consistency.
31.
In Section 4.1.1 (c), you should change " technical criteria" to " criteria."
This change has been made.
32.
In Section 4.1.7, you should remove the reference to Chapter 2, Section 2.7 because it does not contain a
- description of "Preoperational Testing",
This change has been made.
33.
In Section 4.1.8, you should change " Internal" to " Written."
This has been changed.
8
o 34.
In Section 4.2.1.1, you should.hange "When based on experimental data " to "For SIUs based on experimental data,."
This has been changed 35.
In Section 4.2.1.3 (I and m), you should change " evaluation" to " criticality safety evaluation."
This has been changed.
36.
In Section 4.2.2.1 (c)(second sentence), you should change " maximum mist density" to " credible maximum mist density."
This has been changed.
37, in Section 4.2.2.1 (d), you should add at the end of the sentence,"etc. "
This change has been made.
38.
In Section 4.2.4 (i) you should change '" unsafe vessels" to " unfavorable vessels "
This has been changed.
39.
Modify Section 4.2.5, Table 4-4 and Table 4 5, so that it is clear that the tables do not contain all of the major processes.
They do contain what we consider to be the major plant processes.
40.
Provide a title for Table 4-1.
As shown, Part A is titled " Safe Units Limits Meeting Fractional Critical Criteria for Surface Density Modeling" and Part B is titled "Other Operational Limits: 5 w/o 23sU or Less U0 ". We 2
will consider adding an overall title in a future submission.
9
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linclosure 2 to itA98/680 COMilliSTION ENGINEEltlNG,INC.
IIEMATITE NUCl. EAR FUEL, MANUFACTllRING FACILITY LIST OF AFFECTED 1%GES Combustion Engineering is resubmitting a revised Chapter 4, Nuclear Criticality Safety, to Part I of the SNM 33 license application in response to your lleguest Ib. Additional Infbrmation (llAl) dated November 3,1997. A revised Chapter 4 was originally submitted April 17,1997 per our commitment in the Criticality Safety Program Update Plan dated September 20.1996. This program was undertaken to thrmalize and strengthen our criticality safety program, and this revision to Chapter 4 is a key element in meeting the CSI'U objectives. Thi= submissmn constitutes a complete replacement ihr Chapter 4. Since we are resubmitting the revised Chapter 4 in its entirety, we have retained the designation of this edition as " revision 2" with a current common date ihr all pages. This submittal in response to your RAI replaces the submittal dated April 17, 1997. The pages of the license application affected are as ibliows:
1.ist of Affected Paces llektc_Pagg Add Page l' age No.
Ibn Date Page No.
lleL Dalc 4-1 and 4 2 0
1/28/94 41 through 1
1/30/98 43 0
6/14/94 4 23 4-4 through 4-6 0
1/28/94 4-7 through 4-10a 0
4/20!94 4-11 through 4 16 0
1/2S/94 417 and 417a l 1/26/96 4 18 1
12/15/95 4 19 0
1/28/95 l
4 20 through 1.3a 0
4/20/94 4 24 throagh 4 26 0
1/28/94 4-27 1
12/15/95 4 28 0
4/20!94
linclosure 3 to itA98/680 COMilUSTION ENGINEEltlMi, INC.
l ICENSE NO. SNM 33, CilAl'TEll 4 NUCI. EAR CRITICAL.lTY SAFETY Al FECTED l' AGES l
i 4
.lanuary 30,1998
CHAPTER 4 NUCLEAR CRITICALITY SAFETY The administrative conditions and technical criteria in this chapter provide protection against an unplanned nuclear chain reaction (criticality). These conditions and criteria are applicable where fissile materials are to be stored, handled, or processed, and where the quantitles of such fissile materials may create a potential nuclear criticality hazard.
Administrative conditions define:
(a)-
the design philosophy used in the definition of processes involving the handling and storage of special nuclear materials (SNM),
(b) the lines of responsibility for ensuring criticality safety aspects of the process are reviewed, documented, and approved by management, and (c) the written procedures and postings governing the processes for handling and storage of SNM.
Technical criteria provide the bases for:
(a) limits and controls used in the processing, handling, and storage of SNM, (b) criticality evaluations, and (c) engineered process controls.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-1
4.1 Administrative Conditions 4.1.1 Process Design Philosophy The process design philosophy used by Combustion Engineering, Inc. to ensure nuclear criticality safety is based on the following key elements:
(a)
Process design, with respect to the handling and storage of SNM, should, in general, incorporate sufficient factors of safety such that at least two unlikely, independent, and concurrent changes in process conditions are required before a criticality accident can occur. Process design which does not meet these doublo contingency criteria shall be explicitl) approved in Chapter 1, Section 1.6, of this application.
(b)
Physical controls, e.g., favorable geometry and permanently engineered controls shall be the preferred method of criticality control, to reduce dependence on administrative procedures. In some processes, types of control other than favorable geometry, e.g., moderation, concentration, and/or neutron absorbers may be used to achieve safe operations. In these cases, controlled parameters and their limits shall be clearly specified, approved by management as part of the review and approval of operating procedures, and communicated to affected personnel through postings, operating procedures, or training.
(c)
Before a new operation with SNM is begun or an existing operation is changed, it shall be determined that the entire process will be suberitical under normal and credible abnormal operating conditions, consistent with paragraph a) of this section and applicable technical criteria of Section 4.2.1.3.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 42
4 4.1.2 Positions Responsible for Criticality Safety Section 2.1 desciibes the responsibilities and authority for key organizational positions affecting safety. Section 2.2 specifies the p.cessional requirements for these positions.
4.1.3 Documenting Criticality Evaluations and Reviews Criticality evaluations associated with facility changes affecting the handling and storage of SNM in Nuclear Manufacturing shall be documented by a Nuclear Criticality Specialist and Independently reviewed.
The criticality evaluations shall consider potential scenarios which could lead to criticality and barriers erected against criticality in establishing applicable criticality limits and controls.
These limits and controls shall be incorporated into applicable written procedures and/or postings. Postings shall be approved by a qualified Nuclear Criticality Specialst.
j Procedures shall be approved by the Oirector, Regulatory Affairs. Day to-day monitoring cf workers for conformance to criticality limits and controls and administrative procedures shall be carried out by line supervision and Health Physics Technicians.
Documentation of the criticality evalt::stions shall be sufficiently detailed such that an independent reviewer can reconstruct the analysis and bases for the conditions presented. Criticality evaluations shallinclude assumptions affecting criticality safety process limits and controls. If explicit analyses using validated methodologies are used, the margin to criticality and a clear definition of off nominal conditions shall be provided, Criticality evulaations shall include a documented review by a qualified reviewer.
{
Records of the criticality evaluation and review sleall be maintained according to the requirements of Section 2.10 of this license.
License No. SNM 33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-3 i
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4 0
4.1.4 Written Procedures Operations involving the handling and storage of SNM shall be performed according to approved, written procedures.
Operations which include active engineered con'.rols shall have procedures which specify the inspection requirements, the calibration or functional test requirements, or other requirements appropriate for maintaining the active controls. Administrative controls and passive barriers which are relied upon for criticahty safety shall be described in appropriate procedures.
4.1.5 Posting of Limits and Controls Work and storage areas where SNM is handled, processed, or stored shall be posted with the nuclear safety limits and controls applicable to each area. The postings shall be approved by a Nuclear Criticality Specialist.
4.1.6 Labeling of Special Nuclear Material Mass limited containers, with the exception of shipping packages having a valid Certificate of Compliance, us3d in the transport, handling, or storage of special nuclear material shall be labeled with the amount, enrichment, and type of SNM contained.
Empty containers shall be labeled accordingly or placed in designated areas.
Uncovered empty containers do not require an empty sign.-
4.1.7 Preoperational Testing and Inspection Preoperational testing and inspection shall be performed as required by the criticality safety evaluation.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-4
4.1.8 Criticailty 01fety Design Ncw processes or changes in existing processes affecting the handling and storage of special nuclear material shall be evaluated for nuclear criticality safety. Written procedures shall specify appropriate criticality safety reviews and evaluations for facility changes affecting the handling and storage of SNM.
4.2 Technicc
Criteria E
4.2.1 Individual Units O
4.2.1.1 Safe Individual Units (SIU)
For SIUs based on experimental data, an SIU is defined as an iridividual, isolated suberitical unit of fully reflected, optimally moderated SNM whose characteristic mass or geometric parameter is reduced by the applicable safety factor: Mass - 2.3, Volume - 1.3, Slab Thickness - 1.2, Cylinder Diameter - 1.1. For SIUs determined from calculated data, the calculations shall be performed using validated computer analysis methods and the subcritical (safe) limit values calculated consistent v ?h paragraph 4.2.3.3 (a). A conservative process density shall be used.
The resulting units of SNM are Safe Individual Units when isolated from other units by distance or shielding (see Section 4.2.2).
Im License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-5 i
4.2.1.2 Subcritical Units (Subcrits)
Suberitical units other than Slus may use multiparameter controls such as mass, concentration, volume, moderation, etc., to achieve criticality safety. The configuration and composition of these subcritical units may depend upon the process involved and may include allowed individual SNM unit geometries which are less conservative than favorable geometry or defined configurations of individual SNM units in a given process layout.
Uranium concentration control safe units shall be limited to a maximum of 25 grams of l
uranium per liter, The effect of evaporation and/or precipitation shall be considered in the nuclear safety analysis, such that, if precipitated, a safe mass or favorable geometry will not be exceeded. Concentration controlled safe units shall not be considered to contribute to interacting arrays, but shall be located outside exclusion areas assigned by the surface density method.
l
. 4.2.1.3 Criteria (a)_
The possibility of the unintended accumulation of fissile materials in not readily accessible locations shall be minimized through equipment design or administrative controls or included in the criticality safety evaluation of the process.
(b)
Criticality safety evaluations shall include credible sources of internal moderation.
(c)
Criticality safety evaluations shall consider the neutron reflection properties of the environment as well as the heterogeneity of the fissi'e material within the subcrit on the effective multiplication factor. A conservative process density shall be used.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-6 4
(d)
Criticality safety evaluations shallinclude consideration of credible accident conditions consistent with the double contingency priaciple. Safety factors for Sius are defined in 4.2.1.1. For subcrits defined in 4.2.1.2, the highest effective multiplication factor, under normal or credible abnormal operating conditions, shall be less than 0.95 including applicable uncertainties and biases. An acceptable margin of subcriticality may be demonstrated using validated calculational methods or by comparison to existing calculations or critical experiments.
g (e)
Reactivity hold-down by other than fixed neutron absorbers shall not be used in
]
criticality evaluations. Explicit analyses of the effect of structural or fixed neutron absorbers shall use validated raethodologies. The criticality safey evaluation shall address the possibility of depletion of the parasitic isotope (s) in structural or fixed neutron absorbers. Borosilicate-glass raschig rings may be used in solutions of fissile materialin a manner consistent with ANSI /ANS 8.5-1986.
(f)
Whenever criticality safety is directly dependent on the integrity of a fixture, container, storage rack or other structure, design shall include consideration of structural integrity.
(g)
Computer analysis methods shall be validated in accordance with the criteria of Section 4.2.3.2 and Regulatory Guide 3.4, Revision 2, dated March 1986,
" Nuclear Criticality Safety in Operations with Fissionable Materials at Fuels and Materials Facilities". The highest effective multiplication factor derived by the validated analytical me' hods for credible operating conditions shall be less than or equal to 0.95 including applicable biases and calculational uncertainties.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-7
(h)
The analytical method (s) used for the safety evaluation of SlUs and the source of validation of the methods shall be specified.
-(i)
Mass control shall be administered using a calibrated mass measurement instrument.
(j)
Volume control shall be administered by the following methods: 1) geometric devices to restrict the volume; or 2) engineered devices or instrumentation to limit -
the accumulation of SNM.
(k)
Moderation control shall be administered by the following methods to restrict or measurt moderation: 1) instrumentation; 2) physical structure; or 3) a sampling l
l program.-
(1).
When geometry is used as a criticality safety control, the criticality s afety evaluation shall consider the effect of credible bulging or other deformation on criticality safety.
(m)
When 4ss than full neutron reflection is used as a critica!ity safety control, the criticality safety evaluation shall consider the effect of credible upset conditions leading to an increase in reflection on criticality safety.
4.2.2 Multiple Units and Arrays Criticality safety may be based on the use of limiting parameters which are applied to simple geometries. This approach uses safe units which assume optimum moderation and full reflection using published criticality data. Safe units may be arrayed using the surface density method. An alternate empirical method is the Solid Angle Method.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-8 E.-..
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A more rigorous memad is based on two dimensional transport and/or three dimensional Monte Carlo rnethods. These methods permit the evaluation of more complex geometric configurations of SNM and the evaluation of multiparameter control methods.
4.2.2.1 Spacing of Safe Units The following criteria shall be used:
(a)
Application of the surface density method of spacing safe mass, volume, or cylinder diameter lirnited units requires meeting the following criteria:
(1)
Safe mass, volume, or cylinder diameter limited units shall meet the maximum values defined in Table 4-1, Part A.
(2)
The spacing areas for the safe mass, volume, or cylinder diameter limited units of1able 4-1, Part A shall use spacing areas no less than those defined in Table 4-3. Safe units shall use a minimum spacing between units of twelve inches. Coplanar slabs specified in Table 4-1 require no additional spacing; non-coplanar slabs require a minimum spacing of twelve inches.
(3)
Each safe unit shall be approximately centered in its respective spacing area.
(b)
When the above criteria for the surface density model cannot be met, the spacing may be e Ablished by the solid angle method of TID-7016 (Rev. 2) providing that the applicable criteria on subcriticality of the primary unit and subtended solid angle of interacting units are met.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-9
(c)
Criticality safety shall be independent of the degree of moderation between units up to the maximum credible mist density. The credible maximum mist density will be determined by studying sources of water in the vicinity of the single units or errays. The maximum mist density may be limited by design and/or by administrative controls.
(d)
Safety margins for individual units and arrays shall be based on accident conditions such as flooding, multiple batching, fire, etc..
(e)
Optimum conditions (limiting case) of wate. moderation and heterogeneity credible for the system shall be determined in applicable calculations.
(f)
The water content will be verified to be less than 1.0 w/o in powder storage cans which are arranged in two layers on rollers conveyors.
(g)
Vessels and other items of equipment requiring exclusion areas shall have the limits of these areas clearly marked on the floor. Safe units in transit shall not be permitted to enter an exclusion area unless a criticality safety evaluation has shown the transit to be safe.
(h)
The analytical method (s) used for the safety evaluation of the spacing of safe units and the source of validation of the methods shall be specified.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-10
_o
(i)
Part B of Table 4-1 summarizes safe limits for pellets, pellet scrap, and Zircaloy clad pellet colutns. For the purposes of this license, sintered pellet diameters may range kom 0.32 to 0.40 inches. The limits for pellet scrap may be applied to any pellet diameters less than or equal to 0.40 inches. The safe mass limit for pellet scrap is based on the most reactive pellet diameter (0,10"). Randomly stacked pellets are defined as having a volume averaged density of 5.804
- 0.147 g/cc. The average void to UO volume ratio for randomly stacked pellets is 2
0.79965 i 0.04495. Lousely packed rods are defined as rods of a giveri diameter stacked on square or triangular pitches having an average gap between rods of up to 6 percent or up to 14 percent, respectively, of the clad outer diameter. This j
definition is applicable to clad pellet columns containing UO pellets having 2
diameters in the range of 0.3224 to 0.40 inches.
(j)
The safe mass limits of Table 4-1, Part B, include the double batching allowance.
This allowance may be eliminated for operations where double batching is not credible.
(k)
Loaded shipping containers may be stored in an array size not exceeding a total transportation index (TI) of one hundred. Container types may be mixed and the array may contain 927s.
4.2.3 Technical Data and Validation of Calculational Methods 4.2.3.1-Technical Data Safe unit limits which meet the suberiticality criteria for spacing by the surface density method are listed in Table 4-1, Part A. Minimum spacing criteria are as listed in Table 4-3.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-11
4 Mass limited units may be stacked on a vert l cal centerline with at least a 10 inch separation.
Table 4-2 provides safe limits for aqueous solutions with enrichments up to 5 w/o 235U The uranyl fluoride data may be used for UO.
4 Well distributed SNM may be stored based on areal density. Homogeneous material may be stored wit'i a maximum areal density of 5.2 kg UO (t'ive weight percent) per 2
square foot or 229 g 235 2
U/ft. Heterogeneous material may be stored with a maximum areal density of 4.9 kg UO (five weight percent) per square foc,t or 216 g 235 2
U/ft. No 2
spacing is regtdred.
4.2.3.2 Validation of Calculational Methods l
Criticality safety evaluations for SNM process / storage systems using computerized methodologies such as transport and Monte Carlo codes shall use validated models.
These models shall be validated by analysis of pertinent critical or subcritical
' experiments to define the range of applicability of the model and associated bias in calculated eigenvalues. The validation analyses for each model shall be documented consistent with ANSl/ANS-8.1-1983, " Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors," Independently reviewed, and retained according to the requirements of Section 2.10 of this license.
Computer codes used in validated calculational models shall be subjected to formal configuration control procedures. These procedures shall provide a defense against unauthorized changes to the algorithms in the codes. If authorized changes to the codes are made, the procedures shall require appropriate testing to verify the mathematical operations are performed as intended.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-12 9
4.2.3.3 - Other Criteria (a)
For validated computer analysis methods, the highest effective multiplication -
factor for normal or credible abnormal operatirig conditions'shall be less than or equal to 0.95 including applicable biases and calculational uncertainties.
The analytical method (s) used for criticality safety analyses and the source of (b)
. validation of the methods shall be specified.
I 4.2.4 Special Controls The following tect.nical criteria shall be used.
(a)
Process areas containing fissile materials will not have fire sprinkler systems.
Water hoses shall not be used to fight fires in the Oxide Building, and in Building Nos. 253,254; 255,256-1, and 230 (with the exception of the warehouse area).
(b)
The hygrometers on the plant air to the Receivers in the Oxide Building and to the micronizers and blenders in Buildings 254 and 255 will be set to alarm at a dew point no higher than 0 'C and checked on a 6 month interval. The hygrometers on the cooler hopper at the exit of the screw cooler in the oxide building will be -
set to alarm at a dew point no higher than 15 *C and checked on a 6 month period. Upon alarm, automati:: or manual action stops the process. The source of alarm must be investigated and the problem corrected before the process is allowed to contir.
(c)-
The R-2 and R-3 steam lines will have two (redundant) fail-safe shut-off valves, each activated by two independent high and low temperature alarm setpoints on the R-2 and R-3 reactors. The operability of this system will be ascertained at least once every 6 months.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-13
-Q.
The moisture content of the UO powder transferred into the bulk storage (d) 2 hoppers and the recycle storage hoppers will be verified as being less than or equal to one weight percent. The instruments used for measuring moisture in UO shall be calibrated on a 6 month interval. Loading and unloading of hoppers 2
shall be done with hoods that prevent water ingtess.
(e)
The R-1, R-2 and R-3 inlet pressure switches will be tested at least once every 6 months.
(f)
Dual, indepa
,at verifications of moisture content in UO shell be made prior to 2
transfer of...terial into the bulk storage hoppers or into the blenders in Buildings 254 or 255.
(g)
Moderation controlled containers shall be covered such that no moderator can enter the container whea external to protective hoods.
(h)
The number of 5 gallon cr less containers allowed on the second and third floors of Building 254 shall be limited as follows: lubricant and/or poreformer,12 on each floor; UO2 Powder,24 spaced on 2 foot centers on each floor. Additionally, the second and third floors of Building 254 shall be limited on each floor to a maximum of 10 gallons total of water, cleaning solutions, paints and powder moderators (exclusive of lubricant and poreformer) when the poreformer or lubricant mixing operations have material in process.
(i)
UO powder charges added to each poreformer mixer in Building 254 shall not 2
exceed 4.4 kg 235U License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-14
(j)
Fissile aqueous solution transfers from favorable to unfavorable geometry vessels j
in the wet recovery system shall have at least two independent methods for control of the fissile content of the solution prior to release of the solution to the unfavorable geometry vessel; solution transfers shall be limited such that the unsafe vessels never contain more than a safe batch. Physical barriers in piping systems shall exist to prevent the inadvertent transfer of fissile aqueous solutions to unfavorable geometry vessels.
l (k)
Process systems shall be designed to minimize the likelihood for the unanalyzed accumulation of fissile material within the system in addition, process procedures shall have provisions for verifying that fissile material has not inadvertently accumulated within the system, especially in those systems using unfavorable geometry containers.
(l)
Measurement controls sha!! be used whenever geometry controls are not used to ensure criticality safety. Instrumentation used for measurement controls shall be maintained as part of the calibration program or instrumentation qualification program.
(m)
Pellets and pellet scrap transferred in quantities greater than a safe mass between Building 230 and non-contiguous buildings shall be transported within a container that maintains a safe slab geometri (n)
Storage of sintered pellets in the Kardex storage device shall be limited to Kardex storage pans with a maximum of 70 kg of UO in each pan. There shall be a 2
minimum of two physical water barriers over Kardex pans to prevent the ingress of water.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-15
(o)
Criticality safety evaluations for ventilated hoods may be based on either the limits of Table 4-1, Part A, or have specific safety evaluations. For hoods employing more than one limit but based on Table 4-1, Part A, mechanical devices shall be used to ensure that the required minimum separation distance will ba maintained between SNM containers in accordance with Section 4.2.2.1.
(p)
The rod box storage matrix shall be limited to 112 rod storage boxes and prestack boxes. Thera shall be a minimum of two physical water barriers over the rod 3
storage boxes and prestack boxes to prevent the ingress of water.
(q)
Fuel assemblies, when wrapped and stored in the Fuel Assembly Storage Area shall have the bottom end open to ensure drainage of water.
(r)
Isolated fuel assemblies shall be limited to arrays of 16 x 16,14 x 14, and 10 x 10 rods and a maximum array size of 8.048" x 8.048", independent of the nun;ber of rods. Pellet diameters shall be less than or equal to 0.40" and greater than or equal to 0.3224". Fuel assembly designs outside this envelope shall require a criticality safety evaluation to ensure the ass 1.mbly and storage proc 3sses have adequate subcriticality margin.
(s)
Shipping package arrays containing SNM UO product shall be stored within the 2
security fence, in Building 230 or in the parking lot scath of Building 230. Loaded 927 (927A1 and 927C1) shipping packages shall be stored no more than three high. There are no restrictions on +he number of loaded 927 packages or their orientation in the horizontal plane. Loaded fuel shipping packages of types other than 927s shall be separated froin arrays of loaded, unrestricted 927 packages by at least twelve feet.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-16 e.
.n A
.e The volume of UO F solution in the vaporizer chest following a UFe leak and (t) 22 continuing steam flow into the chest shall be controlled by multiple, independent
!evel detection devices which shut off steam flow into the vaporizer.
(u)
Receivers No.1 and No. 2 shall t,... i have a barrier to ensure that no significant moderating material can be brought within 1 foot of the vessel surface.
(v)
The reactor gas filtration system shall have a barrier to ensure that no significant moderating material can be brought within 1 foot of the vessel surface.
4.2.5 C.;ticality Control Variables for Plant Processes Table 4-4 lists the criticality control variables for various major plant processes. Table 4-5 lists major plant processes which are controlled as Safe Individual Units.
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-17 o,
=
+
c ee O
Table 4-1 PART A. Safe Unit Limits Meeting Fractional Critical Criteria for Surface Density Modeling MASS (Kg UO )
2 w/o 235U Homogeneous Heterogeneous
>1.0 - 2.5 54 50
>2.5 - 3.0 41 38
>3.0 - 3.2 36 36
>3.2 - 3.4 35 33 l
>3.4 - 3.6 32 30.
>3.6 - 3.8 28 27
>3.8 - 4.1 24 24
>4.1 - 4.3 22 22-
>4.3 - 4.5 20 20
>4.5 - 4.7 18 18
>4.7 - 5.0 16 16 VOLUME (f)
>1.0 - 3.5 31 22
>3.5 - 4.1 25 18
>4.1 - 5.0 22 17 CYLINDER DIAMETER (In.)
>1.0 - 3.5 10.7 9.5
>3.5 - 4.1 9.8 8.9
>4.1 - 5.0 9.2 8.4 SLAB THICKNESS (In.)
l
>1.0 - 5.0 l
4.0 l (see Part B) l Licence No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-18 M
.g' Table 4-1 PART B. Other Operational Limits: 5 w/o 235U or less UO2-
~
Pellets (1)
Slab Th. (in.)
Cyl. Dia. (in).
-yol,(g)-
Kg UO (2) 2 Randomly Stacked
-4.65 10.2 31.4 90.85 Optimally Moderated-3.75 8.3 17.0 17.45 Pellet Scrap 3.75 8.3 17.0 14.55 Zircaloy Clad Rods-Slab Th.
Cyl. Dia. (in.)-
Loose Packeo (3) 7.15 14.7 l
Optimally Moderated 4.17
9.0 Notes
(1) Pellet OD 0.32" to 0.4" j
(2) Including Double Batching Allowance.
(3) See definition in third paragraph, Section 4.2.2.1, License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-19 s
x
Table 4-2 Aqueous Solution Limits for 235U Enrichments Less Than or Equal to 5 w/o 235U UO F22 UO (NO )2 2
3 235 )(1) 0.82 1.77 Mass (Kg U
Cylinder Diameter (in.)(1) 10.0 16.4 Stab Thickness (in.)(1) 4.42 8.33 Volume (liters)(1) 26.9 105.5 Concentration (g 235U/L)
Critical Limit 273 298 Subcritical Limit (2) 261.0 283.0 l
(1)
With safety margins (2)
ANSI /ANS-8.1-1983 Licensa No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70- 36 Page: 4-20 t..
i - in -,- - - r=>.
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m n..
i
- Table 4-3 Minimum Spacing Areas (1) for Homogeneous and
' ~
Heterogeneous Mass and Geometric Limits Spacing 2
Area (ft )-
Mass 3.5 Volume 9.0 Cylinder.(2),
5.0 (1)- Subject to a minimum edge-to-edge unit separation of 12 inches.
(2)
Per foot of cylinder height, e
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-21
Table 4-4 Criticality Control Variables for Plant Processes Plant Process Control Variable UF Vaporizer Volume - Note 1 6
Reactors R1 and R3 Geometry and Partial Reflection - Note 2 Reactor R2 Note 1 Reactor Offgas Filtration Geometry and Partial Reflection - Note 2 -
Receivers No.1 and No. 2 Geometry and Partial Reflection - Note T.
Bulk Storage and Recycle Hoppers Moderation l
Micronizer and Blender Moderation Buildings 254 and 255 Geometry Oxidation / Reduction Furnaces Slugging, Granulation and Pressing Batch and Moderation
{
SNM Shipment Offsite and Receipt Per Shipping Container Certificate of Onsite -
Comp!iance Kardex Storage Moderation - Note 1 Rod Box Storage Matrix Moderation - Note 1 Fuel Assembly Rack Storage Geometry - Note 1 UO Dryer Assembly Geometry 4
Notes 1.
See also Special Controls, Section 4.2.4.
2.
See also the Design Criteria associated with Partial Reflection, Sections 4.2.1.3(c) and 4.2.1.3(m).
License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Pag;. 4-22 1
d O
Table 4-5 SIU Controlled Piant Processes UF Scrubber 6
UO Cooler-Oxide Building 2
UO Cooler Discharge Hopper-Oxide Building 2
Pellet Press Oil Sump Pellet Handling in Buildings 254 and 255 Grinder Sludge Centrifuge Pellet Grinding Sump UFe Heel Removal Incinerator Oxide Building Trench and Sump Vacuum Cleaners Mop Buckets Building 240 Oxidation / Reduction Furnaces Filter Presses Dissolution Vesseis UO Precipitation Tank 4
UO Centrifuge 4
Hold and Evaporation Tank Complex ADU Piecipitation Tank Steam Cooker Analytical Laboratory License No. SNM-33 Revision 2 Date: 1/30/98 Docket No. 70-36 Page: 4-23
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