ML20236N864
| ML20236N864 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/11/1998 |
| From: | Beckner W NRC (Affiliation Not Assigned) |
| To: | Ronald Bellamy NRC (Affiliation Not Assigned) |
| References | |
| GL-91-18, TAC-MA1696, NUDOCS 9807150316 | |
| Download: ML20236N864 (4) | |
Text
g9.wou Y
UNITED STATES g
j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20665-0001
. wl June 11, 1998 MEMORANDUM TO: Ronald R. Bellamy, Acting Project Director Project Directorate lil-3 Division of Reactor Project lil/IV, NRR A
FROM:
William D. Beckner, Chief y
Technical Specifications Branch Associate Director for Projects, NRR
SUBJECT:
TECHNICAL SPECIFICATION INTERPRETATION ON THE APPLICATION OF DAVIS BESSE TECHNICAL SPECIFICATION 3.6.5.1 AND 3.6.5.2 (TIA 98-005) (TAC NO. MA1696) in a memorandum to Elinor G. Adensam, Acting Director Division of Reactor Projects lil/IV from Geoffrey E. Grant, Director Division of Projects dated April 23,1998 Region ll1 requested that NRR review Davis-Besse (DB) Technical Specifications (TSs) 3.6.5.1,
" Emergency Ventilation System," and 3.6.5.2, " Shield Building Integrity," and determine
. whether the related Limiting Condition for Operation (LCO) Action statements are consistent with both specifications, and whether the licensee's position (TSIR 89-0007) of applying
. only TS 3.6.5.2 in cases where blowout panels or doors in the shield building (SB) have become inoperable, is appropriate. The Technical Specifications Branch (TSB) has reviewed the Action statements and the licensee's interpretation of the subject TS and finds that the Licensee's interpretation is not entirely correct.
At DB, a portion of the auxiliary building is designated the SB. The SB consists of several interconnected areas immediately adjacent to the reactor (containment) building which are maintained isolated from the rest of the auxiliary building to trap and control the release of any airborne radioactive materials released to the SB following a loss of coolant accident
'(LOCA). The SB design incorporates normally closed airtight doors to allow for normal personnel access to the SB, as well as several blowout panels.
' The blowout panels serve two separate safety functions. The first function is to " blow out" in response to a postulated high energy line break to relieve pressure in the enclosed mechanical penetration rooms as wel as to limit pressure on the external portions of the
. containment vessel. The second function is for the blowout panels to remain intact
-following a LOCA to maintain SB integrity, and thereby, limit possible uncontrolled, unmonitored offsite effluent relesses. Assisting with this second function is the SB emergency ventilation system (EVS). It is designed to draw a 0.25 inch WG vacuum on the SB envelope and to process airborne radioactive material from the SB through
' filters /adsorbers to an elevated, monitored release point.
l hU.f
' Q*[. b CONTACT: R.J. Giardina,TSB/NRR
}
h 301-415-3152 l.
9807150316 900611 Y
j' PDR ADOCK 05000346 P
c T
R. R. _ Bellamy 2
June 11, 1998 On November 26,1996, the licensee determined that a blowout panel was inoperable due to the failure of a blowout panel shear bolt. With one blowout panel shear bolt inoperable, the licensee'detwmined that the blowout panel would not remain intact following a LOCA.
Since the surveillance requirement for TS 3.6.5.2 specifically identifies that SB integrity be demonstrated by v6rifying, in part, that all SB envelope airtight doors and blowout panels are closed, the licensee inferred that only TS 3.6.5.2 with its 24-hour LCO action statement should be invoked due to the inoperable blowout panel. Thus the licensee entered TS 3.6.5.2. This position was also documented on a licensee internal TS interpretation (TSIR 89-0007).
The resident inspectors, however, questioned whether TS 3.6.5.1, " Emergency Ventilation System," was also applicable. This was based on the fact that with the blowout panel postulated to be blown out, both EVS trains would be incapable of performing as designed following a LOCA since the 0.25 inch WG vacuum within the SB would not be attainable.
The Region requested responses to the following questions:
1.
When an SB door, blowout panel, or other related SB barrier becomes inoperable, should both SB integrity as well as possible effects on EVS operability be considered in all cases?
No. Based. on the definition of OPERABLE - OPERABILITY, the structure, content and application of the DB TS which requires cascading and generic letter (GL) 91-18 on Degraded Condulons and Operability - Part 9900 " OPERABLE / OPERABILITY" Sections 3.4 " Support System Operability - Understanding System Interrelationships," and 6.12 " Support System Operability," the possible effects of SB inoperability on EVS Operability must be considered in those cases for which SB leaktightness c6nnot be maintained. In order for the EVS to maintain or meet the
- 0.25 inch WG negative pressure (TS 4.6.5.1.d.4) the SB integrity (leak tightness) must be maintained, if the leaktightness cannot be maintained then the actions of l
TS 5.6.5.1, or the Actions of both TS 3.6.5.1 and 3.6.5.2 must be entered depending on the extent of the leakage and the ability of the EVS to maintain negative pressure with the More Restrictive actions taking priority. If the SB 1
inoperability would result in the EVS not being capable of maintaining the negative pressure, then both TS Actions are entered.
' 2.
Does TS 3.6.5.2, " Shield Building Integrity," apply only to inoperable blowout panels and doors, or should other inoperable equipment, such as failed dampers that adversely impact SB integrity, all be included within the scope of TS 3.6.5.2?
The TS surveillance requirements as stated in CFR 50.36(c)(3) specify what the staff considers as the minimum requirements necessary to assure that the quality of the systems and components is maintained, that facility operation will be within safety limits and that the limiting conditions for operation will be met. GL91-18 Section 4.0 " Background" and NUREG 1430 to 1434 Bases STS SR 3.0.1 (DB TS 4.0.1) state that the performance of the surveillance requirements is usually considered to be sufficient to demonstrate operability provided that there is reasonable assurance
R. R. Bellamy 3
June 11, 1998 that the system continues to conform to all appropriate criteria in the current licensing basis (CLB). Whenever conformance to the appropriate criteria in the CLB is called into question, performance of the surveillance requirement alone is usually not sufficient to determine Operability. In this case, DB TS 3.6.5.2 includes more than just the airtight doors and blowout panels specified in TS 4.6.5.2. SB integrity is defined by DB TS definition 1.24 and the information contained in the DB FSAR.
l Thus, failed dampers that adversely impact SB integrity and SB structural integrity would also be included in the scope of TS 3.6.5.2.
3.
With both EVS trains inoperable (and therefore incapable of functioning as designed),
l entry into TS 3.0.3 is required and a plant shutdown initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
However, DB has taken the position (as documented in TSIR 89-0007) that with an inoperable blowout panel or door that involves a potential opening large enough to adversely impact the capability of both EVS trains to function as designed following l
a LOCA, only the 24-hour LCO of TS 3.6.5.2 is applicable. Is the guidance of TSIR 89-007 acceptable?
No, based on the discussion in 1 and 2 above, the guidance of TSIR 89-0007 is not acceptable in all situations. In the event described in the April 1998 memo (shear l
bolt failure), the inoperability could result in en opening in the SB such that the EVS ccu!d not meintain the required negative pressure, in this case, entry into TS 3.0.3 is required, and the guidance in TSIR 89-0007 is not applicable. However, if a blowout panel is inoperable such that it will not blow out in response to a postulated high energy line break, then the guidance of TSIR 89-0007 is applicable, since the EVS can still maintain the required negative pressure.
4.
The licensee recently submitted LER 50-346/97-011-00, which involved the possible adverse effects relating to the breaching of ventilation ductwork while working on a SB isolation damper. Would it be permissible for the licensee to intentionally remove a door, blowout panel or other barrier in the SB envelope for up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />?
Based on the response to question 1 and 3, as well as GL 91-18 Section 6.4
" Operability During TS Survelliances and Preventive Maintenance," the intentional removal of a door, blowout panel or other barrier to gain access to repair, to test, or perform PM on other systems or components is permissible, but the appropriate TS l
actions must be entered for the systems, structures and components made j
inoperable. If the inoperability (removal of the barrier) would result in the EVS not i
being capable of maintaining a negative pressure in the SB, then TS 3.0.3 would be entered. This position is consistent with the conclusion in Davis Besse LER 97-011-00 in which an access door was opened to clean and inspect a valve and the licensee concluded that they should have entered TS 3.0.3, but did not.
R. R. Bellamy 4
June 11, 1998 it should be noted that the improved STS (NUREG 1430 to 1434) does not have this problem (entry into TS 3.0.3 on inoperability of the shield building that leads to inability to maintain negative pressure). The improved STS includes the requirement to maintain or achieve a negative pressure as a SR in the SB (secondary containment in BWRs) LCO rather than the SB ventilation LCO. Therefore, TSB recommends that Davis Besse consider converting their TS to the improved STS.
l l
l I