ML100500982

Spent Fuel Pool Criticality Presentation for Feb 17 Public Meeting

ML100500982
Person / Time
Site:	Millstone
Issue date:	02/17/2010
From:	Sanders C Plant Licensing Branch 1
To:	Dominion Nuclear Connecticut
Sandeers, Carleen, NRR/DORL, 415-1603
References
FOIA/PA-2011-0115
Download: ML100500982 (10)

Text

MP3 RAI 26-30 Response Plan

• RAJ 26

• Issue: Margin needed to cover power history effects

• NUREG/CR-666S estimated history effect magnitude -0.002 LiI<

• Soluble boron used for simulated fuel depletion was cited as a source of margin in RAI 5 response, boron margin information requested

• Response plan - Power history effect margin

• Review NUREG/CR-666S recommendation

• Deplete at constant power and add margin for history effects

• ORNL/TM-12973 says to apply margin as "uncertainty in k-n"

• Conservatively apply as a constant 0.002 LiI< bias in burnup requirement curves using burnup relationship discussed in RAI 2 7( b) response

• No bias needed for fresh fuel with no burnup history

• Penalty will be applied as part of RAI 30 response

MP3 RAI 26-30 Response Plan

• RAJ 26

• Response plan - Provide soluble boron margin

• Analysis used constant 1000 ppm for simulated depletions

• Provide cycle average boron for all completed cycles and current cycle

• Expect 50-100 ppm margin for SPU cycles based on recent cycles and currently operating SPU cycle

• Response plan - Clarify RAJ 5 soluble boron margin response

• 1000 ppm is projected to bound SPU cycles

• Cycle 6 (pre-SPU) had greater than 1000 ppm cycle average boron

• Outlier 21 month cycle

• All Cycle 6 fuel was depleted in at least one other cycle

• Maximum 2 cycle average boron is 1008 ppm

• Very small reactivity impact

• Multiple sources of compensating margin are available (credit as operated moderator temperature)

MP3 RAI 26-30 Response Plan

• RAJ 27(a)

• Issue: Provide code validation or justify not performing a criticality code validation for calculating RAI 21 penalties

• PARAGON / SCALE 5.1 used to develop RAI 21 burnup penalties

• PHOENIX / SCALE 4.4 used for original WCAP 16721 burnup calculations

• Response plan - SCALE 5.1

• Provide code validation information for SCALE 5.1

• Provide a comparison of SCALE 5.1 and SCALE 4.4 uncertainty and bias

• Bias difference between SCALE 5.1 and SCALE 4.4 cancels out for reactivity difference calculations

• Response plan - PARAGON

• PARAGON and PHOENIX are used to calculate isotopic content of depleted fuel determined at reactor operating conditions, not for K-eff in the SFP

• PARAGON SER permits use for the same purposes as PHOENIX

• Bias between PARAGON and PHOENIX cancels out for reactivity difference calculations

MP3 RAI 26-30 Response Plan

• RAJ 27(b)

• Issue: Explain the basis for Table 21-6 (~I( / ~Bu ratios)

• Response plan

• Values in Table 21-6 are superseded by RAJ 30 response

• Basis for the ratios is (K2-KI)/(Bu2-BuI) using values from WCAP Tables 4-9 and 4-10 over a burnup change of io GWD/MTU

• RAJ 27(C)

• Issue: Provide depletion parameters used in RAI 21 response

• Response plan

• Provide a list of depletion parameters used

• Moderator temperature

• Soluble boron

• Core power

• Fuel characteristics

• RAI 21 parameters are bounded by RAI 30 (higher moderator temperature)

MP3 RAI 26-30 Response Plan

• RAI27(d)

• Issue: Response to RAI 21 for No Blanket fuel takes credit for margin that earlier responses already took credit for as conservatisms

• Explain impact on earlier responses

• Explain how bias and uncertainty are affected by use of as-built fuel characteristics ana depletion conditions

• Response plan

• RAJ 21 response crediting as-built conditions was only for Region 2 for already depleted No Blanket fuel .

• Dominion will store all No Blanket fuel in Region 1 or Region 3

• Restriction footnote will be added to TS Figure 3.9-3 (Region 2)

• Region 1 justification:

• RAI 21 issue was justification of axial burnup shapes

• Region 1 burnup requirements are very low

• Uniform axial shape is conservative for low burnup

• Region 3 justification

• All No Blanket fuel was used in pre-uprate cycles

• Existing TS Figure 3.9-4 is basis for this fuel

MP3 RAI 26-30 Response Plan

• RAJ 27(e)

• Issue: Provide RAJ 21 title change to TS Figure 3.9-4

• Response plan

• RAJ 21 response was referring to changes made to TS Figure 3.9 4 that were already provided in the original submittal

• No change needed to TS Figure 3.9-4 as submitted in Dominion letter Serial Number 07-0450

MP3 RAI 26-30 Response Plan

• RAI 28

• Issue: Conflicting DNC and NUREG/CR-6760 conclusions about the effect of IFBA must be resolved

• DNC submittal indicates it is conservative to ignore IFBA

• NUREG/CR-6760 indicates it is non-conservative to ignore IFBA

• Response plan

• Recalculate IFBA effect

• Use maximum previous or proposed IFBA loading, 120 inch IFBA

• Use RAI 21 shapes and models, RAI 30 temperatures

• Determine burnup penalty versus assembly burnup

• Include in burnup penalty described in RAI 30

• Add burnup penalty to TS curves for Region 2 and Region 3

• Burnup requirement is too low for a penalty in Region 1

MP3 RAI 26-30 Response Plan

• RAJ 29

• Issue: Has MP3 used any flux suppression devices?

• RAJ 5 response stated that MP3 fuel management does not use fixed burnable absorbers

• Response plan - flux suppression devices

• MP3 has not used any flux suppression devices in any cycle

• Response plan - Clarify RAI 5 fixed burnable absorber response

• MP3 fuel management has no current or planned use of fixed burnable absorbers

• Batches B, C, and D (pre-SPU Cycles 1 and 2) had fixed absorbers in No Blanket fuel

• Clarification - Region 1:

• Existing TS Figure 3.9-1 bounds SPU analysis and is basis for pre-SPU fuel

• Burnup requirement is very low in Region 1

• Absorber history is not significant at very low burnup

• Clarification - Region 2:

• RAJ 27(d) response does not permit storage of No Blanket fuel in Region 2

• Clarification - Region T

• Existing TS Figure 3.9-4 is basis for pre-SPU fuel

MP3 RAI 26-30 Response Plan

• RAI30

• Issue: Provide the core average moderator exit temperature (nominal flow) and maximum assembly moderator exit temperature (minimum flow)

• It appears that a nominal rather than a conservative value was used

• Response plan

• Provide nominal core average moderator exit temperature (620 .4 F vs 628 F analyzed)

• Provide bounding maximum assembly moderator exit temperature versus burnup based on recent cycle fuel management and minimum TS flow

• Calculate moderator exit temperature penalty using RAI 21 models and burnup profiles

• Sum all relevant penalties

• Bounding exit moderator temperature penalty

• RAI 21 axial node and burnup shape penalty

• RAI 28 IFBA history penalty

• RAI 26 power history penalty

• Increase administrative margin from 0.1% ~K to 0.5% ~K

• Convert penalty to burnup using best estimate ~K/ ~Bu (WCAP Tables 4-9 and 4-10)

• Summarize RAI analysis conservatisms