ML18033A650
| ML18033A650 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 02/14/1989 |
| From: | NRC OFFICE OF SPECIAL PROJECTS |
| To: | |
| Shared Package | |
| ML18033A646 | List: |
| References | |
| NUDOCS 8903030419 | |
| Download: ML18033A650 (5) | |
Text
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NUCLEAR REGULATORY COMMISSION WASHINGTON, O. C. 20555 ENCLOSURE 2
SAFETY EVALUATION BY THE OFFICE OF SPECIAL PROJECTS RELATING TO RELIEF FROM THE BOILER AND PRESSURE VESSEL CODE SECTION XI, "RULES FOR INSERVICE INSPECTION OF NUCLEAR POWER PLANT COMPONENTS - DIVISION 1" TENNESSEE VALLEY AUTHORITY BROWNS FERRY PLANT, UNITS 1, 2, AND 3 DOCKET NOS. 50-259, 50-260, AND 50-296 I. 0 INTRODUCTION Section 50.55a, "Codes and Standards,"
of 10 CFR Part 50 requires, in part, that certain safety-related pumps and valves meet the requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (hereafter "the Code" ).
In order to meet the requirements of this regulation, the Tennessee Valley 'Authority (TVA) has submitted to the NRC its first ten year interval inservice System Pressure Test (SPT) program.
Regulation 10 CFR 50. 55a(g)(6)(i ) authorizes the Commission to grant relief from these requirements upon making the necessary
- findings, and the Commission may authorize alternatives to the Code requirements.
This SE contains the NRC staff's findings with respect to granting or not granting relief request H-12 submitted as part of the licensee's inservice SPT program.
1.1
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Relief from the hydrostatic test pressure requirements for Class 2 components of the 1974 Edition, Summer 1975 Addenda,Section XI of the Code is requested.
1.1
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a.
IWC-5220 Pressure 1.
The system hydrostatic test pressure shall be at least 1.25 times the system design pressure (PD) and conducted at a test temperature not less than 100'F except as may be required to meet the test temperature requirements of IWA-5230.
2.
The test temperature may be reduced in accordance with the following table when system hydrostatic testing is required to be conducted at temperatures above 100'F in order to meet the fracture toughness criteria applicable to ferritic materials of which the system components are constructed.
8903030419 8902i4 PDR ADQCK 05000259 PDR
Test Tem erature Test Pressure 100'F 200'F 300 F
400'F 500'F b.
IMA-5230 Temperature 1.25 PD 1.20 PD 1.15 PD 1.10 PD 1.05 PQ The system leakage test and system hydros tatic pressure test shall be conducted at a test temperature that will satisfy the fnllowing requirements:
1.
The test temperature for the initial preservice system pressure test shall satisfy the requirements specified in Section III.
2.
The test temperature of IMA-5230(a) shall be modified for inservice system leakage tests and system hydrostatic pressure tests (1) as necessary during ihe service lifetime of the nuclear power system, following the results obtained from each set of tests of the material specimens withdrawn from the reactor vessel in accordance with the reactor material surveillance
- program, and (2) as required, to meet the fracture toughness criteria applicable to ferritic materials of system components as specified by the enforcement authorities having jurisdiction at the plant site.
3.
The examinations may be performed after the system pressure has been reduced to a level coincident with a temperature of 200'F.
1.3 Licensee's Basis for Re uestin Relief The portion of the Control Rod Drive (CRD) piping subject to this request has a design pressure of 1750 psig and a design temperature of 150'F.
The applicable Code requires a hydrostatic test pressure of 2188 psig.
The design corfiguration of the Hydraulic Control Unit (185 each in Units 1, 2, and 3) has a piston with pressure seals that should not have differential pressure greater than 300 psig, otherwise they may be damaged.
This limitation requires nitrogen
+o be supplied to the opposite side of the piston within 300 psig of the hydrostatic test pressure, which would be a minimum of 1888 psig.
The nitrogen tank has a rupture disc design burst pressure of 1900 to 2100 psig.
At the minimum hydrostatic test pressure of 2188 psig, the minimum required nitrogen pressure would be 1888 psig which would require the rupture disc to be removed and plugged.
This high pressure nitrogen (1888 psig) poses danger to personnel in that a large quantity of nitrogen is released into the space occupied by the test personnel when the nitrogen tank rupture disc is removed.
If the test pressure i" reduced to 1. 1 times the design pressure, as allowed by IMC-5222 of the 1977 Edition Minter 1977 Addenda and later Codes, the hydro-static pressure will be reduced to 1925 psig, which allows the nitrogen pressure to be reduced to 1625 psig to maintain the 300 psig pressure differential.
This lower nitrogen pressure (1625 psig) does not require the rupture disc to be removed.
Therefore, both the lower nitrogen pressure and not removing the rupture disc will (1) reduce the amount of nitrogen released into plant spaces, (2) simplify the procedure, and (3) reduce the chance of irgury to personnel or damage to equipment.
1.4 Alternative Testin perform CRD system hydrostatic pressure test at 1. 1 times system design pressure (PD) for the Class 2
CRD piping between valves FCV 85-39B and FCV-85-617, and the the piping and components between valves FCY 85-39A, FCV-85-590, FCV-85-589 and hydraulic accumulator water side in the 185 Hydraulic Control Units of Browns Ferry, Units 1, 2, and 3.
2.0 STAFF EVALUATION The NRC staff has reviewed the licensee's relief request H-12 for the SPT of certain class 2 piping (piping and components of 185 Hydraulic Control Units in the Control Rod Drive System in each of the three Browns Ferry Units) at 1.25 times the system design pressure.
The burden of removing 185 nitrogen tank rupture discs for each unit, plugging the openings temporarily and reinstalling the rupture discs af er the tests with the attendant releases of large amounts of nitrogen gas in confined spaces with personnel is significant.
The licensee's submittal includes a
proposal to incorporate an alternative pressure test at 1. 1 versus the required 1.25 times system design pressure.
The performance of system pressure tests at the proposed l. 1 times system design pressure versus the present requirement of 1.25,times system design pressure is allowed by later editions of the Code.
The licensee will be performing these pressure tests'during the next inspection interval to one of these later editions of the Code by the regulations, i.e., at 1. 1 times system design pressure.
3.0 CONCLUSION
Based on the staff review of the licensee's relief request H-12 for Browns Ferry, Units 1, 2, and 3, the staff concludes that the licensee's request for relief from certain specific requirements of Section XI of the ASYiE Code is acceptable.
Any additional program changes such as revisions or additional relief requests should be submitted to staff review and should not be implemented prior to review and approval by the staff.
The staff has determined (1) that relief may be granted pursuant to 10 CFR 50.55a(g)(6)(i) based on our finding that certain requirements of Section XI of the Code are impractical, and (2) that granting relief where the Code requirements are impractical is authorized by law and (3) that
granting relief in conjunctiom with the proposed alternative testing requirement will not endanger life or property, or the common defense and
- security, and is otherwise in the public interest considering the burden that could result if they were imposed on the facility.
Principal Contributor:
D.
E. Smith pated:
February 14,"1989
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