ML20033B435

Forwards Responses to NRC 811118 Informal Questions Re Cycle 4 Reload Rept,Per 811118 Telcon

ML20033B435
Person / Time
Site:	Crystal River
Issue date:	11/20/1981
From:	Cross W FLORIDA POWER CORP.
To:	Office of Nuclear Reactor Regulation
References
3F-1181-31, TAC-46962, NUDOCS 8112010408
Download: ML20033B435 (3)

Text

-

.ee n g.,

,'_l L ;..- *,5 4

8

's

's 1. ',-

'... f I y

g, ' ;;:

ug; M

Pow co a,o.,er io =

g 4'

/g-November 20,1981

/[

< (,h

,.91 3

File: 3-0-3-a-3 Ov3 01981s - $

1. 3F-ll81-31 M u,rMWw B/ /

Director k

U b

7 Office of Nuclear Reactor Regulation s

U.S. Nuclear Regulatory Commission 4

Washington, D.C. 20555

SUBJECT:

Crystal River Unit 3 Docket No. 50-302 Operating License No. DPR-72 Response to Questions on the Crystal River Unit 3, Reload Report (BAW-1684)

Dear Sir:

Enclowd are Florida Power Corporation's responses to informal questions raised by your staff on the Crystal River Unit 3, Cycle 4 Reload Report as discussed by telephone on November 18,1981.

Very truly yours, FLORIDA POWER CORPORATION W. A. Cross

Manager, Nuclear Licensing KFP:gs Enclosure 0f 8112010408 811120 E

PDR ADOCK 05000302

.P P.DR IL 3:

(

General Office 3201 inirty fourin street souin. P O Box 14042. St. Petersburg, Florca '33733 813-866-5151

Response to NRC Questions page 2 Considering the previously accepted design basis used in the FSAR, other transient evaluations for Cycles 3 and 4 are considered to be bounded by previously accepted analyses.

Question 6) What is the value of peak allowable linear heat generation rate (LHGR) for Cycle 3 and Cycle 4.

Response

The maximum LHGR corresponding to centerline fuel melt (Tech. Spec. Limit) is 20.1 KW/FT. Maximum operating LHGR limits are determined by LOCA analyses and are given in Table 7.2 of the respective Reload Reports.

Question 7) Figure 8-4, Pressure / Temperature limit Curves Provide the MDNBR value on which these curves are based.

Response

The curves of figure 8-4 are based on 1.433 MDNBR (1.30 correlation limit, plus 10.2% DNBR used to offset DNBR reduction due to rod bow).

Question 8) Why power and flow changed in Cycle 4 compared to Cycle 3 for these curves.

Response

The power and flow changed due to increased instrument string error adjustments on trip delay time and partial pump power calculations. The Cycic 3 powers are stated as a percent of 2568 MWt (the basis for the analysis) while the Cycle 4 powers as a percent of 2544 MWt (113.05% of 2544 MWt = 112% of 2568 MWt).

I l

l l

l

[

i 9:

6

)?

RESPONSE TO NRC QUESTIONS ON THE CRYSTAL RIVER UNIT 3 RELOAD REPORT Question 1) What is the value of the maximum core bypass flow for Cycle 3 (Cycle 4 value is 8.1%)?

Response

The Cycle 3 maximum core bypass flow is 10.4% based on 108 assemblies with open guide tubes. The 8.1% bypass flow for Cycle 4 is based on the insertion of 64 lumped burnable poison (LBP) rods.

Question 2) You have stated 3.5% DNBR reduction due to rod bow. Do you 2

have sufficient DNBR margin to offset the DNBR reduction?

If you please, provide the magnitude of the margin and source of this margin.

Response

All plant operation limits are. based on minimum DNBR criteria containing the design minimum DNBR limit of.1.30 (B&W correlation) plus a 10.2% DNBR mcrgin available to offset DNBR reduction due to rod bow.

Question 3) Why the DNBR value is increased to 2.05 for Cycle 6, compared to DNBR of 1.98 for Cycle 5, when the incoming batch 6 fuellis 4

hydraulically and geometrically similar to the fuel remaining in the core from the previous cycles.

Response

The DNBR value is increased to 2.05 for Cycle 4 (not cycle 6) i due to the decreased core bypass flow.

(See response to Question 1)

Question 4) Which is the limiting transient.

Question 5) What is the value of minimum DNBR for the limiting transient for Cycle 3 & Cycle 4?

Response (4&5) A difference in minimum DNBR exists for the limiting loss of flow transients analyzed for Cycles 3 and 4 because of increased RPS instrument errors. The following table provides a comparison of MDNBR between Cyc1,es 3 and 4.

Summary of MDNBR Results for Limiting Loss-of-Coolant-Flow Transients i

j.

Transient Cycle 3 (B&W-2)

Cycle 4 (B&W-2)

One-pump coastdown (flux / flow trip) 1.75 1.69 Four-pump coastdown (pump monitor trip) 2.10 2.10

-.