ML17157C341
| ML17157C341 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 05/19/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17157C340 | List: |
| References | |
| NUDOCS 9305280361 | |
| Download: ML17157C341 (8) | |
Text
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kp*y4 UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 ENCLOSURE S
FETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TQ HYDROSTATIC TESTING OF LI UID RADIOACTIVE WASTE PIPING PENNSYLVANIA POWER
& LIGHT COMPANY ALLEGHENY ELECTRIC COOPERATIVE INC.
SUS UEHANNA STEAM ELECTRIC STATION UNITS 1
AND 2 DOCKET NOS.
50-387 AND 388
- 1. 0 INTRODUCTION By letter dated December 14,
- 1990, Pennsylvania Power and Light Company (PP&L or licensee) requested an exemption from hydrostatic testing requirements for a few specified welds and one coupling in certain limited sections of small diameter piping in the liquid radwaste system at the Susquehanna Steam Electric Station, Units 1 and 2.
All of the piping is located in the Radwaste building, which is adjacent to but separated from the two turbine buildings and the two reactor buildings.
2.0 BACKGROUND
The Liquid Waste Management System (LWMS) is described in Section 11.2 of the Final Safety Analysis Report (FSAR).
The system is designed so that no potentially radioactive liquids can be directly discharged to the environment unless they have been monitored and diluted.
The FSAR emphasizes that "the LWMS has no nuclear safety-related function as a design basis."
Major LWMS components are located in separate shielded compartments according to their radiation level.
Rooms of components containing significant amounts of liquid radwaste are provided with curbs and/or elevated door thresholds to retain any leakage.
Floor drains and sloped floors minimize the spread of any leakage and route any leakage to an intermediate pump or drain tank for processing.
Table 11.2-3 in the FSAR lists, among other things, the material of construction and the design pressure and design temperature for the
- pumps, tanks, piping, etc. in the LWMS.
The piping is all Type 304, Schedule 40 stainless steel.
The design pressure ranges from atmospheric to a maximum of 175 psig in one filter aid component.
The design temperature is generally in the order of 150 'F except for the components associated with the radwaste evaporators, which have design temperatures in the 250 'F to 350 F range.
During construction of SSES, system quality group classifications as defined in NRC Regulatory Guide 1.26 were determined by PP&L for each water, steam or radioactive waste system.
These classifications are discussed in Section 3.2.2 of the FSAR.
Section 3.2.2. 1 states that "certain portions of the radwaste system meet the additional requirements of guality Group D
(Augmented) as defined in the NRC Branch Technical Position (BTP)
ETSB ll-l, PDR ADDCK 05000387 P
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Revision 1, Parts IV and VI.
Portions of the radwaste system meeting the requirements of guality Group D (Augmented) may be determined from notes on the appropriate figures in Chapter 11."
This commitment was made in a letter to the NRC from PPKL (who, at the time, was an applicant) dated March 16, 1981, forwarding an FSAR revision to address seismic qualification of some radwaste subsystems.
BTP-ETSB 11-1, Revision 1, "Design Guidance for Radioactive Waste Management Systems Installed in Light-Water-Cooled Nuclear Power Plants" was issued in Hay 1976.
It was subsequently superseded by Regulatory Guide (RG)
- 1. 143, "Design Guidance for Radioactive Waste Management
- Systems, Structures, and Components Installed in Light-Mater-Cooled Nuclear Power Plants" which was initially issued in July 1978.
Revision 1 to RG 1.143 was issued October 1979, lq years prior to the March 16,
- 1981, commitment letter from PPKL.
The commitment to BTP ETSB ll-l was apparently not a significant consideration in the staff's initial assessment of the liquid radwaste systems at SSES.
In Section 11.2. 1 of NUREG-0776 (The NRC staff's Safety Evaluation Report for SSES, Units 1 and 2) issued April 1981, the staff found the liquid
'adwaste systems fully acceptable with no mention of either BTP ETSB ll-l or RG 1. 143.
The only area in which the commitment to BTP ETSB ll-l was apparently a consideration in the staff's assessment of the SSES design was for the gaseous radwaste system.
In Supplement No.
1 to NUREG-0776 dated June 1981 in Section 11.2.2, "Gaseous Waste Management Systems",
the staff referenced the March 16, 1981, letter from PPLL and stated:
"The letter provided a commitment by the applicants to modify Table 3.2-1 of the Susquehanna Steam Electric Station FSAR to show compliance with BTP ETSB ll.l.
We find this to be acceptable."
From the above, it is evident that the quality group classification and quality assurance provision for the liquid radwaste system at SSES were, at most, "guality Group D (Augmented)"
as defined in Parts IV and VI of BTP ETSB 11-1, Revision 1.
BTP ETSB ll-l, Revision 1 (and RG 1. 143) in Table 1 on Equipment Codes specifies that Radwaste piping and valves be designed and tested in accordance with ANSI B 31. 1 (American National Code for Pressure
- Piping, "Power Piping" sponsored by the American National Standards Institute (ANSI) and the American Society of Mechanical Engineers (ASHE)).
Since the construction records were not available, the writer could not determine what specific edition of B 31. 1 Bechtel used to design the systems but it likely was the Hay 1, 1977, edition.
In any case, for purposes of this assessment, the specific edition is not significant, since in the 20-year period between the 1967 edition and the 1986 edition (which more than spans the period that SSES Units 1 and 2 were under construction) there were no significant revisions in Sections 136 (Examination and Inspection) or Section 137 (Leak or Pressure Tests) of Chapter VI of ANSI B 31.1.
BTP ETSB 11. 1, Revision 1 specifies in Section IV "Additional Design, Construction and Testing Criteria" part "C." that:
"Completed process systems shall be pressure tested to the maximum ractical extent (emphasis added by writer).
Piping systems shall be hydrostatically tested in their entirety except at atmospheric tank connections where no isolation valves exist.
Testing of piping systems shall be performed in accordance with applicable ASME or ANSI codes, but in no case less than 75 psig.
The test pressure should be held for a minimum of 30 minutes with no leakage indicated.
Testing provisions should be incorporated to enable periodic evaluation of the operability and required functional performance of active components of the system."
Chapter VI of ANSI B 31.1, "Examination, Inspection and Testing" and more specifically Sections 136 and 137, specifies the testing that should be performed on systems designed and constructed in accordance with this Code.
The pertinent sections to this assessment are:
136.4.2 137.3.4-137.3.5 137,3.6
- 3. 0 EVALUATION Visual Examination states that "Visual examination consists of observation of whatever ortions of a com o ent or weld are ex osed to such observation, either before, during or after manufacture, fabrication, assembly or test.
(Underlining by author)
Required Hydrostatic Test Pressure.
Piping systems shall be subjected to a hydrostatic test pressure so that every point in the system is not less than 1.5 times the design pressure.
Hydrostatic Test Pressure Holding Time.
The hydrostatic test pressure shall be continuously maintained for a minimum time of 10 minutes and for such additional time as may be necessary to conduct the examinations for leakage.
Examination for Leakage.
Examinations for leakage shall be made of all joints and connections.
The piping system exclusive of possible localized instances at pump or valve packing shall show no visual evidence of weeping or leaking.
The licensee's letter of December 14, 1990, stated that "hydrostatic testing per the requirements for D-Augmented piping systems of NRC Branch Technical Position ETSB 11-1 was performed.
However, certain welds and couplings could not be visually inspected during the hydrostatic tests.
Therefore, this letter requests an exemption from the hydrostatic testing requirements for those welds and couplings."
The Commission has provisions for granting relief from certain ASHE Code requirements in accordance with 10 CFR 50.55a(g) for ASHE Code Class 1,
2 and 3 components.
The liquid radwaste piping is properly classified as Class D piping and was properly constructed in accordance with the ANSI B 31.1
Code.
The inservice inspection requirements of 10 CFR 50.55a do not apply to Class D piping. If a licensee does not meet a test requirement of the ANSI B 31.1
- Code, the licensee should evaluate and disposition the deviation in accordance with 10 CFR 50.59.
In discussions with the licensee's staff, they have concluded that the hydrostatic test they performed in 1987, coupled with the tests performed by Bechtel prior to acceptance of the liquid radwaste piping system, successfully demonstrated the integrity of the system, even though all welds could not be visually inspected.
Therefore, we reviewed the licensee's submittal as though it were a
10 CFR 50.59 determination.
For the reasons discussed
- below, we agree that the licensee has met the"leak testing requirements of NRC BTP ETSB 11.1 and ANSI B 31.1.
In discussions with the licensee's staff, they reported that Bechtel had not only radiographed all welds but had also performed a liquid penetrant examination of the welds in addition to hydrostatically testing the piping.
The hydrostatic test was conducted for at least the 30 minutes specified in BTP ETSB 11. 1 vs. the 10 minutes specified in ANSI B 31. 1.
Some editions of ANSI B 31. 1 state that:
"Where a hydrostatic test is not practical, an initial service leak test, a vacuum test, or 100 per cent radiography of all welded joints in an all-welded system may be substituted" (for the hydrostatic test).
The ANSI B 31. 1 requirement is to test at 1.5 times the design pressure.
The licensee's staff reported that the test pressure was at least 1.5 times the design pressure for each subsystem and that the pressure was held for at least the 30 minutes specified in BTP ETSB 11. 1.
During the 1987 rehydro-test, there were 10 field welds on the 3" Reactor Water Cleanup Phase Separator piping that were not visually inspected.
The welds are inside the Phase Separator Tank Rooms in a high radiation area.
Dose rates inside these tank rooms are in the order of 150 to 200 R/hour.
The design pressure for this 3" line is 140 psig.
A 2-gpm Teledyne hydro pump was used for the test and required only one stroke every 5 minutes to maintain pressure.
This stroke rate is consistent with the results of other hydro-tests performed at SSES where the field welds were fully visually inspected and no leakage was detected.
There has been no indications of leakage in this line in the subsequent 6 years of operation.
As noted previously, if there was any leakage in any of the liquid radwaste piping or components, it would be collected and processed.
The nondestructive examination previously performed on these welds could be considered an acceptable substitute for visual examination.
We conclude that the licensee visually examined the welds in this 3" line to the maximum practical extend and the hydro test satisfactorily met the requirements of both BTP ETSB 11.1 and ANSI B 31. 1.
During the 1987 hydro tests, there was a socket-welded coupling on the 2" spent resin transfer pump discharge line (to the liquid radwaste filters) that could not be visually inspected.
Design pressure for this 2" line is 160
psig.
The 2-gpm Teledyne pump that was used in the above test was also used to hydro this pump discharge line.
The coupling is located in a pipe chase which is inaccessible and also in a high radiation area.
The section of 2" piping with the coupling is located in a pipe chase enclosed on all sides and on top with stacked concrete shield blocks mortared in place.
In addition, a concrete slab has been poured over the top of the blocks for use as a walkway.
No entrance to this pipe chase exists.
The hydro pump required only 1 stroke every 2 minutes to maintain pressure.
We conclude that the licensee visually examined the weld in this 2" line during the hydro test to the maximum practical extent.
Considering the preservice, non-destructive examinations, hydro test, and the absence of leakage in the 6 years since the rehydro test was performed, we also conclude that the 1987 rehydro-test satisfactorily met the requirements of both BTP ETSB 11. 1 and ANSI B 31. 1.
Also located in the same pipe chase as the above coup1ing, is a 4" discharge line from the radwaste collection tank whose design pressure is 125 psig.
There were 3 field welds on this line that could not be visually inspected during the 1987 hydro test for the reasons discussed above.
The 2 gpm teledyne hydro pump used in the test required only 1 stroke every 2 minutes to maintain pressure in the piping.
Although the 3 welds could not be visually examined during the hydro test, there was no indication of water on the floor of the pipe chase.
The licensee concluded that they had visually examined all welds in this piping to the maximum practical extent.
We agree.
We also agree with the licensee's determination that the 1987 rehydro test satisfactorily met the requirements of both BTP ETSB11. 1 and ANSI B 31. 1.
4.0
SUMMARY
a.
The liquid radwaste piping at
- SSES, Units 1 and 2, is classified as Quality Group D (Augmented) or Qua1ity Group D and was designed and fabricated in accordance with the ANSI B 31. 1 Power Piping Code.
For this class piping, the licensee can evaluate and disposition hydrostatic test results under 10 CFR 50.59.
b.
The licensee committed to meet the additional requirements of Quality Group D (Augmented) as defined in BTP ETSB ll.1, Revision 1, Parts IV and VI.
With respect to hydrostatic tests, BTP ETSB 11. 1 specifies that the test pressure be maintained for 30 minutes versus the 10 minutes specified in ANSI B 31. 1.
The licensee has confirmed that in the 1987 hydrostatic tests of the liquid radwaste
- systems, test pressures were maintained for 30 minutes and the test pressure was at least 1.5 times the design pressure of the subsystem being tested.
c.
BTP ETSB 11. 1 specified that during hydrostatic tests, welds be visually examined to the maximum practical extent.
The licensee's position is that during the 1987 rehydro tests, they met this position.
We agree.
d.
The licensee's current position is that the 1987 hydro tests met the requirements of BTP ETSB ll.1 and ANSI B 31. 1 and demonstrated the structural integrity of system welds.
This has been supported by 6 years of operating experience.
We treated this position as though it were a
10 CFR 50.59 determination and reviewed the hydro test results on this basis.
We agree with the licensee's determination.
e.
Exemptions are neither necessary nor appropriate.
Principal Contributor:
R. Clark Date:
May 19, 1993
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