ML20050B566

Advises That RTD Bypass Loop Flow Rate Periodical Verification Is Not Necessary.Requests NRC Reconsider Matter.Results of Analysis Re RTD Loop Transport Delay Time Encl.Proper Valve Alignment Will Be Verified

ML20050B566
Person / Time
Site:	Wolf Creek, Callaway, 05000000
Issue date:	04/02/1982
From:	Petrick N STANDARDIZED NUCLEAR UNIT POWER PLANT SYSTEM
To:	Harold Denton Office of Nuclear Reactor Regulation
References
RTR-NUREG-0830, RTR-NUREG-830 82-018, 82-18, NUDOCS 8204060057
Download: ML20050B566 (4)

Text

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SNUPPS Standardized Nuclear Unit Power Plant System 5 Choke Cherry Road Rockvdle, Meryland 20850 (301)869 8010 April 2,1982 SLNRC 82 018 FILE:

0543.1 SUBJ:

Callaway SER-Proposed Technical Specification 4C

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Mr. Harold R. Denton, Director

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Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Conunission g

Washington, D. C. 20555 f.

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Docket Nos:

STN 50-482 and STN 50-483

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Reference:

NUREG-0830, Callaway Safety Evaluation Report CI 4

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Dear Mr. Denton:

997 p

The referenced report states in Sections 7.2.2.2 and 16. that the NRC plans to require in the Technical Specificatior.s that RTD bypass loop flow rate be periodically verified.

The SNUPPS Utilities do not believe this verification is necessary and request that the NRC reconsider the matter.

During the review of the SNUPPS FSAR, the NRC's Instrumentation and Control Systems Branch (ICSB) expressed a concern that flow degradation in the bypass loops could adversely affect the response time of the temperature signals provided for reactor protection. The NRC stated that flow degradation could be caused by corrosion product deposition or improper valve line-ups.

1.0 second.

The safety analyses use a conservative assumption of 2.0 hDO l The functional requirement for the RTD loop transport delay time is seconds for the manifold transport time and heating. An analysis was 5

performed to calculate the delay time for the condition that return line flow is equal to 90 percent (the low flow alarm setpoint) of the

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flow for clean piping. This flow reduction was assumed to be caused by fouling in the hot leg only in order to give the maximum delay time.

The results of the analysis are as follows:

8204060057 820402 PDR ADOCK 05000482 A

PDR

I SLNRC 82 018 -

Page Two Delay Times (Sec.)

Loop Hot Leg Cold Leg 1

.84

.84 2

.84

.74 3

.81

.97 4

.94

.81 Theref e, if fouling occurred suco that the flow rate was reduced to the.ow flow alann, the systen would still meet the 1.0 second functional requirement.

Another evaluation consisted of:

(1) calculation of the current RTD Bypass System delay time with no fouling (base line resistance coef-ficients), and (2) calculation of the effect of increased fouling (increased resistance coefficients) on the systen delay times.

Figure 1 is a plot of the increase in the hot and cold leg transport delay time as a function of the percent increase in piping loss coefficient due to fouling.

Loop 1 was used as a representative loop to generate this plot but Loops 2, 3, and 4 behave similarly. Summa-rizing this part of the evaluation, the hot lea loss coefficients would have to increase by the anounts listed below before the 1.0 second maximum delay time would be reached.

Increase in H.L. Loss Coefficient Loop Necessary for 1.0 Sec. Delay Time 1

100%

2 103%

3 106%

4 68%

Changes in loss coefficients of this magnitude are not credible.

Cancerning improper valve line-ups, the SNUPPS Utilities will verify proper valve alignment after any maintenance or testing that requires valve operation.

An independent, second operator check of the valve line-up will also be made. This administrative procedure is similar to that used in other safety systems where proper valve line-up is important.

In addition, if any one valve were inadvertently left closed, the flow through the return loop would be less than the low flow alarm setpoint and a low flow alarm would occur.

SLNRC 82- 018 Page Three Based on the above evaluation, the SNUPPS Utilities do not believe that the additional surveillance suggested by the NRC Staff is justified.

-Your attention to this matter is appreciated.

Very truly yours, 9

Nicholas A. Petrick RLS/mtk4b8-10 cc:

G. L. Koester KGE D. T. McPhee KCPL D. F. Schnell UE T. E Vandel NRC/WC J. H. Neisler NRC/ CAL f

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