FRAPCON/FRAPTRAN Code Users Group Meeting
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FRAPCON/FRAPTRAN Code Users Group Meeting Effect of additional He production From B 10 mixed into the fuel. Ulsan National Institute of Science and Technology. Westin Charlotte Hotel, Charlotte September, 2013. I. INTRODUCTION. Current Burnable Absorbers: mostly integrated into fuel

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FRAPCON/FRAPTRAN Code Users Group Meeting Effect of additional He production

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Frapcon fraptran code users group meeting effect of additional he production

FRAPCON/FRAPTRAN Code Users Group Meeting

Effect of additional He production

From B10 mixed into the fuel

Ulsan National Institute of Science and Technology

Westin Charlotte Hotel, Charlotte

September, 2013


I introduction

I. INTRODUCTION

Current Burnable Absorbers: mostly integrated into fuel

  • Gd2O3, ZrB2 coated on fuel surface

    Concern over timely supply of Gd

    Development of B burnable absorber mixed in the fuel

    Use of B absorber in UO2 fuel

  • Preservation of B contents during sintering: BN : relatively good stability until the completion of sintering

  • Generation of He & Li by the absorption of neutron: affect the fuel performance

10B + n 7Li + 4He


Frapcon fraptran code users group meeting effect of additional he production

  • II. Evaluation Methods

In GASPRO, He production from U fission (hmgp) is calculated as:(cumulative amount if the fuel is burnt until time t with the heat flux qc)

where hmgp(t) = The amount of He produced from fission at time t [moles]

qc = Heat flux at the time t

ProblemTime(t) = Cumulative time at the time t

dco = outer diameter of cladding [ft]

deltaz = length of axial node [ft]


Frapcon fraptran code users group meeting effect of additional he production

  • II. Evaluation Methods

In subroutine “gaspro”, effective helium production at the beginning of the time step and at the end of the time step (using the total time to this point and the local power) are calculated.

The actual production ina timestepis calculated as the production from the previous time step plus the difference of the two previous quantities.


Frapcon fraptran code users group meeting effect of additional he production

  • II. Evaluation Methods

He Production from the absorption of neutron by B10

where HeProd(t) = The amount of He produced from added

B10at time t

= Boron moles at initial time [moles]

BU(t) = the burnup until the time t [GWD/MTU]

= the enrichment of the fuel

a,b,c= constants

The amount of He produced at time ‘t’ can be calculated as a function of BU(t)

(Chungchan Lee)


Frapcon fraptran code users group meeting effect of additional he production

  • II. Evaluation method

To sum-up hmgp(t) and Heprod(t), burnup of each axial node in Heprod(t) is simply calculated by using local power and uranium fuel mass ,like hmgp calculation.

The He produced in the time step is calculated as hmgp(end of time step) – hmgp(beginning of step) : calculated in TOTGAS subroutine


Frapcon fraptran code users group meeting effect of additional he production

  • II. Evaluation Methods

The actual cumulative production (hmgpt) is calculated at the production from the previous time step plus the difference of the two previous quantities.

He Production from fission


Frapcon fraptran code users group meeting effect of additional he production

He Production and B10 depletion

  • He production by B10 is added to the He from fission of U

  • : GASPRO & TOTGAS subroutines in FRAPCON

  • Total cumulative He production(hmgpt) is calculated in subroutine TOTGAS


Frapcon fraptran code users group meeting effect of additional he production

The total He production (both from fission and B10) is calculated in GASPRO as the sum of hmgp and Heprod as follows:

Current total He production is calculated as the

Hmgpt (total He) = hmgpt(prev. step) +

[ hmgp(End of current step) – hmgp(Beginning of current step)]

Total He production from fission and B10


Frapcon fraptran code users group meeting effect of additional he production

(i+1)th time step

(i-1)th time step

ORIGINAL

FRAPCON

GASPRO subroutine

hmgp(Beg.)

hmgp(End)

hmgp(End)

FRAPCON-UNI

GASPRO subroutine

hmgp(Beg.)=

hmgp(Beg.)+Heprod(Beg.)

hmgp(End)=

hmgp(End)+Heprod(End)

hmgp(Beg.)

Heprod(Beg.)

Heprod(End)

(i)th time step

TOTGAS subroutine

hmgpt(i) = hmgpt(i-1) +[hmgp(End) – hmgp(Beg.)]

Beginning(Beg.)

End


Frapcon fraptran code users group meeting effect of additional he production

He release to the gap : Booth model : FRAPCON recommendation

Fission gases release : F-M model with PNNL modification

Total amount of He released


Frapcon fraptran code users group meeting effect of additional he production

  • II. Evaluation Methods

Input description :PWR, UO2 fuel

6 cycle irradiated high BU rod : ~ 70 GWD/MTU : N05


Frapcon fraptran code users group meeting effect of additional he production

  • III. Results and Discussion

The total He : both from B10 and U fission.

300, 450, and 500 ppm boron by modified FRAPCON code,

and compared with original UO2 fuel (0 boron).

  • Fission gas release: rapidly

  • increases after ~36 GWD/MTU,

  • He release: continuous increase


Frapcon fraptran code users group meeting effect of additional he production

  • III. Results and Discussion

Rod Internal Pressure

  • minor influence of boron addition

  • up to 500ppm

Possible reasons

The less-than-expected release fraction of He compared with that of fission gas

The smaller production of He (by boron addition) compared with that of fission gas in the fuel rod

The difference in the release calculation models for He and fission gases


Frapcon fraptran code users group meeting effect of additional he production

  • III. Results and Discussion

Most of the He is generated until early stage of the burnup and then stays the same, while fission gas productions are continuously increasing.

The cumulative amount of the production of He is about 1/10 of fission gases

Gas Production


Frapcon fraptran code users group meeting effect of additional he production

  • III. Results and Discussion

Until medium burnup level(~37GWD/MTU), the RF of Xe is much less than that of He, but rapidly increase after that BU.

The RF of He is higher than those of other fission gases, but still in the 1~2.5 % range.

Cumulative release fraction (RF)


Conclusion

Conclusion

Considering the additional helium generated by neutron absorption of B10, the helium production terms in FRAPCON-UNI are modified well.

Based on booth model, helium release fraction should be higher than those of fission gases considering diffusivity , but at the end of life, fission gas(Xe) show a relatively higher release fraction than that of helium.

Like fission gases release, Forsberg-Massih model might be applied for evaluating helium release in the future.


Frapcon fraptran code users group meeting effect of additional he production

Thank you for your kind attention!


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