ML19294A499
| ML19294A499 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/05/1978 |
| From: | Gilleland J TENNESSEE VALLEY AUTHORITY |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7812070170 | |
| Download: ML19294A499 (7) | |
Text
e TENNESSEE VALLEY AUTHORITY CH AT. ANOOGA, TENNESSEE 374o1 830 Power Building December 5, 1978 Director of Nuclear Reactor Regulation Attention:
Mr. Thomas A. Ippolito, Chief Branch No. 3 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Ippolito:
In the Matter of the
)
Docket No. 50-259 Tennessee Valley Authority
)
This is in response to your letter of November 22, 1978, to N. B. Hughes concerning a request for additional information to complete your review of the reload analysis for cycle three operation of Browns Ferry Nuclear Plant unit 1.
Enclosed is the additional information requested by your November 22, 1978, letter.
Very truly yours, f
hL 11f
/J. E. Gilleland Assistant Manager of Power Enclosure 7812070 1lo
\\\\
f An Equal Opportunity Employer
BROWNS FERRY L' NIT 1 RELOAD ANALYSIS FOR CYCLE 3 REQUEST FOR ADDITIONAL INFORMATION DOCKET No. 50-259 Question 1:
The transient analyses in the BF-1 submittal have been performed with the REDY code. A new improved code, ODYN, which is based on first principles, has been presented by GE.
The staff review of ODYN is expected to be completed within the next few months. The GE presentations show that the REDY code is more sensitive to the RPT than the ODYN code yielding lower ACPR values.
In order to assure the staff that the proposed change to the operating MCPR limits does not overestimate the benefit from RPT, we request that BF-1 supply an ODYN licensing basis reanalysis of transients. This should include an analysis of the load rejection without bypass (LRWOB),
turbine trip without bypass, and the feedwater controller failure.
Each of these transients with RPT should be analyzed with the proposed licensing basis ODYN code (as applied in letter from E. D. Fuller (GE) to D. F. Ross (NRC), June 26, 1978, Impact of ODYN Transient Model on Plant Operating Limit s).
Further, in order to verify the margin in the REDY and ODYN licensing bases, a best estimate ODYN analysis (as applied in the above referenced letter) of the LRWOB with RPT should be presented.
Without these evaluations some adjustment of the operating limit MCPR may be required in order to account for the possible non-conservatism of REDY when compared to ODYN.
Response
As stated in your question, the improved ODYN code has not been fully reviewed by NRC.
Therefore, to request that TVA supply an ODYN licensing basis reanalysis of any of the transients is unwarranted.
Until NRC's review of ODYN is complete, TVA's transient analyses will be based on the accepted REDY code.
Picase refer to TVA letter of November 30, 1978, to T. A. Ippolito from J. E. Gilleland concerning this subject on Browns Ferry unit 3.
Question 2:
In section 5.2. A of the proposed Technical Specifications (p. 330), line two should read:
"168 fuel assemblies of 63, fuel rods each" for the 8x8 fuel.
Response
This is correct.
We tequest that the Project Manager for Browns Ferry make the correction as stated in the question.
Question 3:
In Figure 8 of NED0-24136, should the righthand side curve be 100% rod line?
Response
No, the righthand side curve should be the 105% rod line. This is documented in NED0-24136 Revision 1, November 1978, submitted by TVA letter, J. E. Gilleland to H. R. Denton of November 30, 1978.
Question 4:
Provide a description of the modifications to the safety and safety / relief valves.
Response
The exist ng safety valves will be removed f rom their respective headers and two relief valves will replace them. These valves will be installed in the same manner as the existing 11 relief valves with tail pipes extending into the torus, etc.
A general description of the existing relief valve configura-tion is found in FSAR section 4.4.
The setpoints for these new valves are listed in the proposed technical specifications. All torus loads have been recalculated and found to be acceptable.
Also, the 3 stage topworks on six relief valves will be replaced with the more reliable 2 stage topworks.
Question 5:
Provide reference in Technical Specifications for ECCS LOCA analyses for small line breaks which assumed that 4/6 ADS valves were operable.
Response
Please have the Project Manager for Browns Ferry add the following sentence to the,last paragraph on page 167 of the proposal submitted by TVA's September 8, 1978, letter (TVA BFNP TS 115).
"The analyses supporting two ADS valves being out of service are presented in NEDO-24056 which was supplemented by TVA letter of October 28, 1977, J. E. Gilleland to E. G. Case and NEDO-24136."
Question 6:
Verify that the limiting pressure and power increase transient is the load rejection without bypass.
Response
Please refer to NEDO-24136, August 1978, page 3 item 9.
The limiting pressure and power increase transient is the load rejection without bypass. This is confirmed in NEDO-24136 Revision 1 dated November 1978 which you received by TVA's letter from J. E. Gilleland to H. R. Denton of November 30, 1978.
_3_
Question 7:
In section 3.6.D.1 of the proposed Technical Specifications, " orderly" is misspelled.
Response
Please have the Project Manager for Browns Ferry spell " orderly" correctly.
Question 8a:
Concerning the spectrum of postulated fuel loading errors, either show that any fuel loading error is detectable by the available nuclear instrumentation and hence correctable before fuel fails, or show that the consequences of of any fuel damage will remain a small fraction of the 10 CFR 100 guidelines.
The staff currently considers it sufficient if the operating reactor adjusts the operating limit MCPR such that the core wide safety limit MCPR will not be violated for the worst case fuel loading error.
Response
The core wide MCPR will be adjusted as necessary for the singic worst loading error.
Question 8b:
In our May 1978 SER on NEDE-24011P, we have approved alternate fuel loading error analyses, subj ec t to the conditions specified therein.
Please state whether your fuel loading analysis is the original model, or one of the alternates.
Response
T\\a's original submittal of NEDO-24136 of September 8, 1978, was based on the original model.
Ilowever, our submittal of November 30, 1978, J. E. Gilleland to 11. R. Denton utilizes the new method of fuel loading analyses.
Question 9:
Document in appropriate detail that the end-of-cycle RPT systems will be part of the reactor protection system, will fully conform to IEEE 279-1971, and will be appropriately qualified as Class lE equipment.
Response
The response to this question will be provided later.
Question 10:
In order that compliance with the single failure criterion can be verified, provide the control logic diagrams, P&ID's, and schematic diagrams for the RPT systems (including sensors, operating bypasses, and maintenance bypass features).
Response
The response to this question will be provided later.
Question 11:
Relative to IEEE 279 Section 4.20, describe the trip status indications for the RPT systems.
Response
Trip annunciators for RPT system A and RPT system B exist in the main control room.
Question 12:
Relative to IEEE 279 Section 4.12 and 4.24 describe the bypass status indica-tions for the RPT system.
Response
Out of service (bypass) annunciators for RPT system A and B exist in the main control room.
Question 13:
Relative to IEEE 279 Section 4.17, discuss the provisions for manual initiation of the RPT system.
Response
Manual initiation (breaker trips) can be accomplished f rom the auxiliary instrument room or the remote broaker switchgear.
Since be'cafit is derived from RPT only as a fast acting automatic system, there is no particular reason to have the operator's control room console equipped with manual RPT trip controls to supplement the normal pump trip controls.
Question 14:
The GE report NEDO-24119 discusses the testability of the RPT system.
a.
Relative to IEEE 279 Section 4.11, describe the bypass capabilities that are provided tu facilitate or.-line testing.
Response
Either RPT system may be bypassed independently from the auxiliary instru-ment room using a keylock switch.
RPT protection for both pumps is pre-served with om system in bypass.
b.
Relative to IEEE 279 Section 4.14, describe the means provided to control access to bypass capability.
Response
The auxiliary instrument room is a restricted area controlled by card-key access to authorized personnel. Also, the "RPT System Out of Service" annunciators in the main control room would alert the unit operator to unauthorized bypassing of the RPT logic, c.
-roposed note 17 for Table 3.2.B of the Technical Specifications allows both RPT systems to be out of service at one time for monthly f unctional testing. This is not acceptable as a regular condition. An acceptable procedure would be to functionally test only one RPT system at a time.
Also if both RPT systems are inoperable for a time comparable to the proposed testing time (8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />) reactor power should be reduced to
<30% or MCPR operating limits should be reduced to those for transient analyses without RPT.
Response
In order to test the four auto-scram channels during the monthly "stop valve closure" RPS surveillance, various pairs of stop valves are simultaneously closed by 10% (switch setpoint).
Certair. combinations of the tested stop valves will also trip both RPT systeme. Therefore, it is necessary to pit both RPT systems in " test" mode for a short time during the surveillance test to prevent tripping the recirculation pumps.
Nominal test duration is 5-15 minutes, add is done at reduced power (70-90%
maximum). Considering the brief time spent in the test condition and reduced power level, we have concluded that the present test methods are quite rear.anable.
Furthermore, it has been previously concluded that complete failure of the RPT is tolerable even under worst-case conditions.
(See November 18, 1978, unit 3 SER for Amendment No. 18.) At present, if both RPT systems become inoperable, we elect to reduce power to below 30% until the systems are returned to service. The expense of additional transient analyses without RPT is unwarranted in that this condition is very unlikely.
Question 15:
Provide startup test procedures and surveillance rcquirements for conservative verification of RPT delay times and flow coastdown calcu-lational assumptions. There should be a maximum and minimum specifi-cation on the delay time and flow rate coastdown.
Provide the LRWOB results of calculations with the minimum specification on delay time and the f ast flow coastdown.
Response
Startup tests will be conducted to measure the RPT delay time and flow coastdown rate for comparison with the transient calculational assumptions.
These tests have already been performed on BF-2 and acceptable agreement with the predicted response was observed.
Sufficient surveillance instructions will be written to comply with the proposed technical specificatirns.
Limiting transient results from LRWOB have been submitted in the reload licensing package.
Question 16:
Submit a procedure or propose a Technical Specification which provides for periodic testing of the response time of the RPT system.
Specifically, such ter-ing should demonstrate that the system can terminate the current to the pump motors in less than 200 milliseconds after the receipt of the sensor signal.
Response
The response time of the RPT system will be checked during the upcoming startup retest program. This testing not only requires tripping recircu-lation pumps, but extensive special test instrumentation and considerable engineering support. The RPT logic is of similar quality to the RPS logic, which has been well characterized with respect to response time.
- Also, there is no reason to expect sensible variation in the RPT trip breaker cycle time.
The pump current interrupt time will not be measured, but rather the flow coastdown rate.
.