ML15264A411
| ML15264A411 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 08/28/1986 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Tucker H DUKE POWER CO. |
| References | |
| NUDOCS 8609100129 | |
| Download: ML15264A411 (8) | |
Text
gust 28, 1986 Dockets Nos. 50-269, 50-270 and 50-287 Mr. Hal B. Tucker Vice President - Nuclear Production Duke Power Company P. 0. Box 33189 422 South Church Street Charlotte, North Carolina 28242
Dear Mr. Tucker:
SUBJECT:
CORE FLOOD TANK - REQUEST FOR ADDITIONAL INFORMATION REGARDING: Oconee Nuclear Station, Units 1, 2 and 3 The current Technical Specifications for Oconee Nuclear Station Units 1, 2 and 3 (Oconee) require that, during normal reactor operation, an orderly reactor shutdown be commenced immediately upon the discovery of a low boron concentration in the core flood tanks (CFT).
On September 12, 1984, you requested an amendment to the Technical Specifications and,proposed that you be allowed 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> to correct a low boron situation before the commencement of the required reactor shutdown.
Due to leaking check valves, at times the CFTs suffer a slow influx of coolant from the reactor coolant system (RCS) which results in 'a low boron situation in the CFTs. When this occurs, several boron concentration adjustments are required to correct the CFT situation. Also, CFT'boron concentration changes have occurred as a result of leaking isolation valves in the CFT makeup system, along with the operators intentionally draining CFT coolant to keep the required CFT level within the allowable value. We understand that you submitted the proposed amendment to avoid the necessity of shutting down the reactor whenever a CFT low boron situation occurs. On November 22, 1985, to support the proposed change you submitted an analysis of a main steam line break accident with no boron in the CFTs. Your analysis showed acceptable consequences.
To complete our review, we need the additional information identified in the enclosure. We request that you respond to this request for additional 8609100129 860828 PDR ADOCK 05000269 P
-2 information within sixty days of receipt of this letter. The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under P.L.96-511.
Sincerely, John F. Stolz, Director PWR Project Directorate #6 Division of PWR Licensing-B
Enclosure:
As: stated cc w/enclosure:
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Mr. H. B. Tucker Oconee Nuclear Station Duke Power Company Units Nos. 1, 2 and 3 cc:
Mr. William L. Porter Mr. Paul F. Guill Duke Power Company Duke Power Company P. 0. Box 33189 Post Office Box 33189 422 South Church Street 422 South Church Street Charlotte, North Carolina 28242 Charlotte, North Carolina 28242 J. Michael McGarry, III, Esq.
Bishop, Liberman, Cook, Purcell & Reynolds 1200 Seventeenth Street, N.W.
Washington, D.C.
20036 Mr. Robert B. Borsum Babcock & Wilcox Nuclear Power Generation Division Suite 220, 7910 Woodmont Avenue Bethesda, Maryland 20814 Manager, LIS NUS Corporation 2536 Countryside Boulevard Clearwater, Florida 33515 Senior Resident Inspector U.S. Nuclear Regulatory Commission Route 2, Box 610 Seneca, South Carolina 29678 Regional Administrator U.S. Nuclear Regulatory Commission 101 Marietta Street, N.W.
Suite 3100 Atlanta, Georgia 30303 Mr. Heyward G. Shealy, Chief Bureau of Radiological Health South Carolina Department of Health and Environmental Control 2600 Bull Street Columbia, South Carolina 29201 Office of Intergovernmental Relations 116 West Jones Street Raleigh, North Carolina 27603 Honorable James M. Phinney County Supervisor of Oconee County Walhalla, South Carolina 29621
ENCLOSURE OCONEE CFT BORON REQUEST FOR ADDITIONAL INFORMATION
- 1. The NRC allows licensees and applicants to utilize the RETRAN computer code for licensing calculations if the intended user has demonstrated the ability to accurately model the plant and utilize the code. Since Duke apparently intends to justify the proposed Technical Specification change by the main steam line break (MSLB) calculation submitted, please submi't the information required by Generic Letter (GL) 83-11, "Licensee Qualification for Performing Safety Analyses in Support of Licensing Actions,' dated February 8, 1983, to demonstrate Duke's capability to properly use RETRAN. (A copy of GL 83-11 is attached.)
- 2. Listed below are some of the more important parameters for the original and new MSLB analyses.
SAR SLB SBL REANALYSIS MAXIMUM REACTIVITY
-.04
-.04 TIME OF MAXIMUM REACTIVITY 50 SEC 240 SEC RCS TEMP AT END OF TRANSIENT 550 DEGF 400 DEGF Explain the differences citing any different input parameters, dif ferent features of the codes used and any other relevant differences.
Also include a comparison of the original and new analyses predicted DNBR. Is the new MSLB calculation intended to be the new licensing basis MSLB calculation? If so, describe how this MSLB case bounds other MSLB cases.
- 3. How is it concluded that other design basis transients and accidents need not be re-examined to support the proposed Core Flood Tank (CFT)
Technical Specification change? For example, if any other design basis event assumes a non-zero CFT boron concentration, why shouldn't the impact of the proposed change be examined in that event?
- 4. The CFT boron concentration specification in the B&W Standard Tech nical Specifications (STS) is a good model to use in writing Technical Specifications. (A copy of the CFT boron concentration STS is attached.
Please explain Duke's position on modelling the boron concentration Technical Specification after the STS.
The STS has a provision for sampling CFT boron concentration whenever appropriate as dictated by the CFT level fluctuations.
Please explain Duke's position on having this feature in the Technical Specification.
Is keeping a high boron concentration in the CFT on a permanent basis a practical way to reduce incidences of low CFT boron concentration?
Given the (presumably known) valve leak rates and assuming you use a good boron monitoring procedure, how low could the CFT boron con centration go before being detected?. From this concentration, :how long would it take to get the boron concentration up to 1835 Dpm?
-2 Has Duke investigated any hardware changes that would mitigate the low boron problem such as (1) adding heat tracing so that a higher boron concentration could be kept in the CFT, (2) getting bigger supply lines to the CFT so that the boron concentration could be adjusted more quickly, (3) putting boron meters in the CFTs?
In the STS the action required for a CFT low boron situation is to attempt to correct the problem within one hour, after which an orderly shutdown must be commenced if the problem is not resolved.
The STS allows 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to sample the CFT boron concentration.
Discuss Duke's ability to control the CFT boron concentration on this time scale.
- 5. Describe the extent of back leakage past the two CFT discharge check valves that is being observed. Does this leakage meet the require ments of the In-Service Testing (IST) program? What attempts have been made to rectify the leakage problem? What analyses or tests have been done to ensure that, given the leakage problem, the check valves will not either fail to properly open or fail in the fully open position?
3/4.5 EMERGENCY CORE COOLING SYSTEMS (ECCS) 3/4.5.1 CORE FLOODING TANKS LIMITING CONDITION FOR OPERATION 3.5.1 Each reactor coolant system core flooding tank shall be OPERABLE with:
- a.
The isolation valve open,
- b.
A contained borated water volume between (
) and (
) cubic feet of borated water,
- c. Between (2270) and (
) ppm of boron, and
- d.
A nitrogen cover-pressure of between (575) and (625) psig.
APPLICABILITY:
MODES 1, 2 and 3*.
ACTION:
- a. With one core flooding tank inoperable, except as a result of a closed isolation valve, restore the inoperable tank to OPERABLE status within one hour or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
- b. With any core flooding tank inoperable due to the isolation valve being closed, either immediately open the isolation valve or be in at least HOT STANDBY within one hour and be in HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
SURVEILLANCE REQUIREMENTS 4.5.1.1 Each core floodinq tank shall be demonstrated OPERABLE:
- a. At least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by:
- 1. Verifying (by the absence of alarms) the contained borated water volume and nitrogen cover-pressure in the tanks, and
- 2.
Verifying that each tank isolation valve is open.
- b.
At least once per 31 days and within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of each solution volume increase of greater than or equal to (1% of tank volume),
by verifying the boron concentration of the tank solution.
- With Reactor Coolant pressure oreater than (800) psig.
B&W-STS 3/4 5-1 JUN 15 17
February 8, 1983 TO ALL OPERATINIl REACTOR LICENSFES SIIJECT:
LCFNS(EE.0UALIFICATION FoR PERFORMING S'JTY ;ALYSES I" SUPPORT OF L IC7NS1P; ACTIONS (Generic Letter No.
p3-11)
Gent 1 lwepon:
The puronse of this letter is to inforn you of t'e current practfce renardinq licensee Qualification for perforoinq safety analyses in supoOrt of licensing Actions.
Over the past few years, the nunber of licensees electina to performi their own safety analyses to support reload applications, technical specification anendments, etc... rather than contract the work out to their NSSS vendor or other ornanizations has increased substantially.
'W encourage utilities to verfonm their own safety analyses since it sionificantly imoroves their ti nderstandiri of plant behavior.
pC's exuerience with safety analyses using large, complex thernal-hydratulic comnuter codes such as PELAP and TRAC has shown that a large percentane of all errors or discrepancies discovered in safety andalses can he traced to the user rather than to the code itself. This realization has led NRP to Olace additional enphasis on assuring the capabilities of the code users as well-as on the codes themselves.
For example, for the past two years URP has been working with the Vendor Inspection 3ranch in Region IV to in snect the acceptability of the QA procedures used for code develoorlent, verification, use, and maintenance for all licensees and vendors involved with safety analysis codes presently under staff review.
While this aspect of our review focuses orinarily on the competence of the licensee and vendors regarding quality assurance practices, the technical cometence of the licensees and vendors with respect to their ability to set up an input deck, execute a code, and properly interpret the results must also he assured.
MRR obtains this assurance by reviewing the code verification information submitted by the licensee or vendor.
The information we look for includes conarisons perforned by the user of the code results to experirvental data, plant operational data, or other henchmarked analyses.
We are concerned however, that some licensees Planning to perforn their own safety analyses clay not intend to denonstrate their ability to use the code by perfon.inq their own code verification.
Rather, they plan to rely on the code verification work previously perfomoed by the code developer or others.
8302030304 OfFIE SURNAAE DATE ).........................
!rR does not conrsijder this accentable and each licensee or vendor wh.
intends to usje A safety analysis computer code to support licensinq actions should (henonstrate their grnficiency in usinq t0e code by subnittinq code verifi catinn nerforied by ther.i, not others.
In order to Clirinate problens on future licensing suhnittals, I request that you factor this into your future licensinq suhmittal plans.
Original signed by Darrell G. Eisenbut Darrell G. Eisenhut, Director flivision of Licensin.