2CAN118702, Application for Amend to License NPF-6,revising Tech Spec 3/4.7.1.1 to Allow Main Steam Line Hydrostatic Test During 2R6 Refueling Outage.Related Info Encl.Fee Paid
| ML20237B449 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 11/30/1987 |
| From: | Tison Campbell ARKANSAS POWER & LIGHT CO. |
| To: | Calvo J NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20237B452 | List: |
| References | |
| 2CAN118702, NUDOCS 8712160271 | |
| Download: ML20237B449 (6) | |
Text
r-s ARKANSAS POWER & LIGHT COMPANY CAPIT0L TOWER BUILDING /P. O. B0X 551/UTTLE ROCK, ARKANSAS 72203/(501) 377 3525 November 30, 1987 T. GENE CAMPBELL Vice President Nuclear Operations 2CAN118702 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Attn:
Mr. Jose A. Calvo, Director Project Directorate IV Division of Reactor Projects III, IV, V and Special Projects
SUBJECT:
Arkansas Nuclear One - Unit 2 Docket No. 50-368 License No. NPF-6 Technical Specification 3/4.7.1.1 Change Request 1
to Allow Main Steam Line Hydrostatic Test During 2R6
Dear Mr. Calvo:
AP&L is scheduled to perform a 10 year hydrostatic test on the ANO-2 Main Steam System during the upcoming 2R6 refueling outage, presently scheduled to begin in early February 1988.
This hydrostatic test is required by Section XI of the ASME Boiler and Pressure Vessel Code, to which ANO-2 is committed by Section 4.0.5 of the Technical Speci fications.
The hydrostatic test will be performed using steam as the pressurizing medium as allowed by the 1980 edition of the ASME code.
The test will be performed with the reactor at hot standby (Mode 3) conditions using reactor coolant pump heat.
The ASME required test pressure is 1.05 times the system design pressure at the test temperature.
Therefore, in order to perform this test, eight of the ten main steam code safety valves must l
l be gagged (rendered such that they will not open) and the two remaining valves reset, as the current setpoints are below the required test pressure.
The two
]
operable valves will be reset to a value above the test pressure but low enough to provide appropriate overpressure protection.
i l
The present ANO-2 Technical Specification (TS) 3/4.7.1.1 requires that all main steam line code safety valves be operable in Mode 3, with lift settings as specified in Table 3.7-5.
This specification is based on requiring sufficient safety valve steam relief capacity to dissipate the heat energy generated at certain reactor power levels.
TS Table 3.7-1 specifies the maximum allowable power level for operation with less than the total number of operable safety valves.
A smaller amount of energy is created during the hydrotest, therefore sufficient relief capacity will exist with two of the safety valves operable.
Therefore, we are proposing a change that would allow gagging of the safety valves for the hydrostatic test.
A similar change was approved for ANO-1 by issuance of TS Amendment 90, dated December 20, 1984 (ICAN128405).
k g
8712160271 071130 I) g }c,(e c k f / $ 0 0 0
,\\
PDR ADOCg 050 B
P
..,v.oea Mioot.s soum uviuries svsteu'
. November 30,.1987 AP&L has evaluated the proposed changes in accordance with 10CFR50.91(a)(3) using the criteria in 10CFR50.92(c) and determined that these changes involve no significant hazards consideration.
The bases for this determination are included as an attachment to this proposed change submittal.
The circumstances of this amendment request are not exigent or emergency; however, expeditious processing is necessary as this change will be required for the main steam hydrostatic testing, presently scheduled to begin immediately after the power reduction for the 2R6 refueling outage in February 1988.
A copy of this amendment request has been sent to Ms. Greta Dicus, Director, Division of Radiation Control and Emergency Management, Arkansas Department of 4
Health, in accordance with 10CFR50.91(b)(1).
Pursuant to 10CFR170.12(c), we are including a check in the amount of $150.00 an application fee for the processing of this amendment.
Very truly yours,
- Miuru
%[
3 T. Gene Campbel I
TGC:rbt Attachments cc:
Ms. Greta Dicus, Director Division of Radiation Control and Emergency Management Arkansas Department of Health 4815 West Markham Street Little Rock, AR 72201 l
1 1
STATE OF ARKANSAS
)
)
SS COUNTY OF PULASKI
)
I, T. Gene Campbell, being duly sworn, subscribe to and say that I am Vice President of Nuclear Operations for Arkansas Power & Light Company; that I have full authority to execute this oath; that I have read the
~
document numbered 2CAN118702 and know the contents thereof; and that to the best of my knowledge, information and belief the statements in it are true.
l A
wa Y5
/
T. Gene Campbell SUBSCRIBED AND SWORN T0 before me, a Notary Public in and for the County and State above named, this [ day of MO/gn(/X4 >
i 1987.
l 1
Notary Public My Commission Expires:
9-/ H 9
..~
DESCRIPTION OF AMENDMENT REQUESJ The Inservice Inspection Progtam for ANO-2 is based on the 1974 Edition of Section XI of the ASME Code (the Code), through Summer 1975 Addenum, which requirer Class 2 systems to be hydrostatically tested at 1.05 times the design pressure of the system if the test temperature is above 500 F.
The design pressure of the ANO-2 main steam system is 1085 psig (ANO-2 SAR Chapter 4).
The main steam system is unisolated from the main steam code safety valves and the hydrostatic test pressure is higher than the set pressures of the main steam code safety valves.
Therefore, to accompli A Re test requirements, AP&L proposes to gag (render the valves such that they will not open) eight of the ten safety valves, reset two at a higher pressure than the test pressure, and utilize reactor coolant pump heat to produce steam as the pressurizing medium
-as allowed by the 1980 Edition of Section XI of the Code.
The test is presently planned to be performed after the plant power reduction to hot standby conditions (with the reactor subcritical), before proceeding with the plant cooldown to cold shutdown for the 2R6 refueling outage.
Main steam system pressure will be maintained at the required test pressure (between 1160 and 1200 psig) using the Steam Dump and Bypass Control System.
The minimum pressure is based on the Code minimum test pressure plus an allowance for measurement uncertainties; the maximum is based on the code safety valve manufacturer's recommendation for maximum setpoint increase.
The two operable code safeties will be reset to 1200 -10 +0 psig from their normal setpoints of 1132 psig.
Sufficient overpressure protection can be provided by only one of the code safeties, as the total steam produced by reactor coolant pump and reactor decay heat input, conservatively calculated, amounts to less than 20% of the steam j
relief capacity of one main steam code safety valve.
The test will be conducted with the Reactor Trip Breakers (RTBs) open to assure adequate shutdown margin.
Using steam instead of water for the pressurizing medium allows the hydrostatic test to be performed at hot standby (Mode 3) conditions and results in significant savings in outage time and resources.
Hot standby is a convenient plant condition for steam system hydrostatic testing, and is also the point at which other secondary equipment can be tested, such as setting the moisture separator reheater safety setpoi.its, and performing the main turbine overspeed trip setpoint test.
Performing the hydrostatic test using water would require removing the existing main steam code safeties and replacing them with blank flanges, and providing an alternate means of overpressure protection, such as installing relief valves.
The potential for damage to any steam safeties is i
great in the event they are required to relieve water instead of steam.
The ASME required test pressure would be 1.25 times system design pressure if the test temperature was betweEn 100 F and 200 F.
Valve removal ar.d replacement, filling the main steam system with water after the plant is in cold shutdown, then pressurizing the water to the required test pressure would require a significant amount of additional outage time and resources.
As presently written, ANO-2 Technical Specification 3/4.7.1.1 requires tnat all ten of the main steam line code safety valves be operable if the reactor is at i
and above Mode 3 (hot standby) conditions.
The proposed change would make an exception to tHs specification when the reactor is in Mode 3 and the secondary system hydrostatic test is being performed.
A similar change was approved for ANO-1 by issuance of TS Amendment 90, dated December 20, 1984 (1CNA128405).
Additionally, the proposed change would require that the RTBs be open for the duration of the hydrostatic test.
This assures that adequate protection is-maintained for SAR Chapter 15 events, such as Uncontrolled CEA Withdrawal, CEA Ejection and Main Steam Line Break, by requiring that all CEAs be inserted in the reactor core and effectively preventing their withdrawal.
DETERMINATION OF SIGNIFICANT HAZARDS Arkansas Power & Light Company has performed an analysis of the proposed change in accordance with 10 CFR 50.91 (a)(1) regarding no significant hazards consideration using the standards in 10 CFR 50.92(c).
A discussion of these standards as they relate to this amendment request follows:
)
i Criterion 1 - Does Not Involve a Significant Increase in the Probability or Consequences of an Accident Previously Evaluated.
The proposed change would not involve an increase in the probability or consequences of an accident previously evaluated because the reactor would not be critical and the pressures in the main steam system would not exceed the design margin.
Although the hydrostatic test requires the main steam system to be at a higher than normal pressure, sufficient overpressure protection will be provided by the two operable code safety valves.
Therefore, the probability of j
a main steam line break (MSLB)-accident will not be increased.
Notwithstanding the evaluation that the proposed change did not represent an increase in MSLB l
probability, the hydrostatic test slightly affects the initial conditions l
assumed in the SAR evaluation of the spectrum of MSLB accidents, so these.
I effects were evaluated to assure that they did not involve an increase in the 3
consequences of a MSLB.
The elevated secondary system pressure will require a I
higher primary system average temperature because of the thermodynamic coupling I
at the Mode 3 plant conditions (the main steam system pressure is the saturation pressure for the existing RCS temperature).
A RCS average temperature of 545 F at Hot Standby results in a daturated secondary steam pressure of about 1000 psi.
The required hydrostatic test pressure upper bound of 1200 psi will correspond to a RCS average temperature about 20*F higher.
In the event of a postulated MSLB, this could result in a slightly greater cooldown, and therefore a slightly greater positive reactivity addition, than that assumed in the MSLB evaluation.
{
However, the consequences of a postulated MSLB would still be bounded by the MSLB accident analysis.
The analysis contains much conservatism, for example, it assumes bounding CEA (rod) worths and Moderator Temperature Coefficient (MTC) of Reactivity.
The hydrostatic test will be performed with significantly greater available shutdown margin and a much less negative MTC.
The negative reactivity associated with these considerations is much greater than the slight additional positive reactivity addition made possible by the elevated secondary system pressure; therefore, an increase in the consequences of a postulated MSLB is not involved, i
The higher RCS average temperature associated with the elevated main steam system pressure required for the hydrostatic test was also evaluated for any affects on related Chapter 15 events, such as the Uncontrolled CEA Withdrawal from a Subtritical Condition and the CEA Ejection.
Although the conservative assumptions used for the SAR Chapter 15 analyses would still bound the consequences of these events with the higher initial RCS temperature, AP&L has elected to perform the hydrostatic test with all CEAs inserted in the reactor core, and has proposed the TS change to require that the RTBs shall be open for the dura' ion of the test to effectively prevent any possible CEA withdrawal scenario. The worth of the assumed ejected CEA is less'than the amount the core will be subcritical.
Therefore, an increase in the probability or j
consequences of a CEA withdrawal or ejection event is not involved.
At the end of core life, criticality can not occur at hot conditions with all rods l
inserted.
Additionally, the available shutdown margin and dilution monitor l
administrative procedural requiremEA further assure that an increase in the l
probability or consequences of a Boron dilution event is not involved.
j i
t
I l
Criterion 2 - Does Not Create the Possibility of a New or Different Kind of I
Accident from any Previously Evaluated The proposed change would not create the possibility of a new or different kind of accident from any previously evaluated.
Analyses of a spectrum of MSLB and CEA withdrawal accidents were performed for the ANO-2 FSAR and evaluated again for each core reload to demonstrate acceptable consequences.
Allowing a system hydrostatic test will not create the possiblity of a new or different kind of accident.
Any postulated accident that could result from such a change would be bounded by accidents previously evaluated.
Criterion 3 - Does Not Involve a Significant Reduction in a Margin of Safety The proposed change would not involve a significant reduction in a margin of safety because the energy required to provide the pressures for testing could t
be dissipated through the two operable (ungagged) code safety valves, thus preventing an overpressure in the main steam system.
This would provide the same or higher level of protection normally provided to the steam system by the ten safety valves when the reactor is operating at full power.
In addition, the proposed change would allow testing such that the steam system will not incur the stresses which would result from the weight of the water if tested by water pressure.
Although it could be perceived that the proposed change could allow some reduction in a margin of safety by allowing a higher than normal main steam pressure with a lower steam relief capacity, hydrostatic testing is required by ASME Section XI and, in fact, preserves the margin of safety by demonstrating the integrity of the main steam system pressure boundary.
It could also be perceived that the higher _RCS average temperature associated with the elevated secondary system pressure required for the hydrostatic testing could reduce the margin of safety, but as discussed under Criterion 1 above, this potential effect is slight and is offset by the conservatism inherent in the accident analyses and the conditions under which the testing will be performed.
The Commission has provided guidance concerning the application of the standards for determining whether a significant hazards consideration exists.
This J
guidance includes examples (51 FR 7750) of typos of amendments that are considered not likely to involve significant hazards considerations.
The change proposed in this amendment is not directly comparable to any of the examples j
identified in 51 FR 7750.
1 Based upon the above evaluation, AP&L has determined that the proposed change does not involve a significant hazards consideration.
)
l i
i 4