ML20197B370
| ML20197B370 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 05/10/1986 |
| From: | Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | Noonan V Office of Nuclear Reactor Regulation |
| References | |
| SBN-1043, NUDOCS 8605130008 | |
| Download: ML20197B370 (10) | |
Text
-
I' SEABROOK STATION Engineering Office Ll Pubec Service of New HampeNro Mew Hompshire Yankee Division May 10, 1986 SBN-1043 T.F. B7.1.2 United States Nuclear Regulatory Commission Washington, DC 20555 Attention:
Mr. Vincent S. Noonan, Project Director PWR Project Directorate No. 5
Reference:
(a) Construction Permits CPPR-135 and CPPR-136, Docket Nos. 50-443 and 50-444
Subject:
Primary Auxiliary Building (PAB) Radiation Monitor
Dear Sir:
The Seabrook Station FSAR Section 12.3.4.2.2(c), " Primary Auxiliary Building Monitor - Channel 6532," states that the sample withdrawal point for this monitor is upstream of Filter Train F-16.
In fact, the actual plant configuration has the sample withdrawal point downstream of the filter train.
We were requested by your Mr. R. Serbu to provide a discussion on the existing design and a justification for the present configuration. provides that justification and concludes that the isokinetic nozzles for RM-6532-1 and RM-6532-2 can remain downstream of the PAB ventilation filters. Attachment 1 provides the necessary FSAR changes which will be incorporated in the FSAR via a future amendment.
Should you or your staff have any questions, please do not L<.sitate to contact us.
We do request that the acceptability of this subject be reflected in a future supplement to Seabrook Station's SER.
Very truly ours,
- -ds[.
d60513OOO8 860910
/
PDR ADOCK 00000443
/s. f A
PDR John DeVincentis Director of Engineering Attachments cc: Atomic Safety and Licensing Board Service List
\\
P O Bor 300. Sootwook, NH 03874 Totophone (603) 474.%21 o
,h'
\\
Diane Curran, Esquire Calvin A. Canney j
Harmon & Weiss City Manager 2001 S. Street, N.W.
City Hall Suite 430 126 Daniel Street Washington, D.C.
20009 Portsmouth, NH 03801 Sherwin E. Turk, Esq.
Stephen E. Merrill, Esquire Office of the Executive Legal Director Attorney General U.S. Nuclear Regulatory Commission George Dana Bisbee, Esquire Tenth Floor Assistant Attorney General Washington, DC 20555 Office of the Attorney General 25 Capitol Street Robert A. Backus Esquire Concord, NH 03301-6397 116 Lowell Street P.O. Box 516 Mr. J. P. Nadeau Manchester, NH 03105 Selectmen's Office 10 Central Road Philip Ahrens Esquire Rye, NH 03870 Assistant Attorney General Department of The Attorney General Mr. Angie Machiros Statehouse Station #6 Chairman of the Board of Selectmen Augusta, ME 04333 Town of Newbury Newbury, MA 01950 Mrs. Sandra Gavutis Chairman, Board of Selectmen Mr. William S. Lord RFD 1 - Box 1154 Board of Selectmen Kennsington, NH 03827 Town Hall - Friend Street Amesbury, MA 01913 Carol S. Sneider, Esquire Assistant Attorney General Senator Goc!'n J. Humphrey Department of the Attorney General 1 Pillsbury street One Ashburton Place, 19th Floor Concord, NH 1
Boston, MA 02108 (ATTN: Hert Jo).ston)
Senator Gordon J. Humphrey H. Joserh Flynn, Esquire U.S. Senate Office ?f General Counsel Washington, DC 20510 Federsi Emergency Management Agency (ATTN: Tom Burack) 500 C Street, SW We M. ton, DC 20472 Richard A. Hampe Esq.
Hampe and McNicholas Paul Mc2achern, Esquire 35 Pleasant Street Matthew T. Brock, Esquire Concord, NH 03301 Shaines & McEachern 25 Maplewood Avenue Donald E. Chick P.O. Box 360 Town Manager Portsmouth, NH 03801 Town of Exeter 10 Front Street Gary W. Holmes, Esq.
Exeter, NH 03833 Holmes & Ells 47 Winnacunnet Road Brentwood Board of Selectmen Hampton, NH 03841 RFD Dalton Road Brentwood, NH 03833 Mr. Ed Thomas FEMA Region I l.
Peter J. Mathews, Mayor 442 John W. McCormack PO & Courthouse City Hall Boston, MA 02109 Newburyport, MA 01950 Stanley W. Knowles., Chairman Board of Selectmen P.O. Box 710
[
North Hampton, NH 03862
ATTACHMENT 1 SBN-1043 SB 1 & 2 Amendment 49 FSAR May 1983 f
Indication ans alarm is available locally and in the main control room for both units.
See Subsections 5.2.5.3.b.2, 5.2.5.5.b and 5.2.5.5.c for a further discussion of monitoring requirements.
(b) Waste Process Building Monitor - Channel 6531 The major potential release of airborne radioactivity in the waste processing building is that associated with
.the gaseous waste processing system. The gas dryers, carbon delay beds and the two gas compressors are situated in their individual compartments, and these compartments are ventilated in such a way that they are at a negative pressure with respect to surrounding areas. The ducted ventilation exhaust is continuously sampled and monitored.
The sample is returned to the ducted ventilation exhaust line which is directed to the Unit 1 vent.
Both the sampling point and the return are downstream of the filters in the ventilation-exhaust line outside the building.
Information from this channel is displayed and alarmed on the radiation monitoring system panel in the main control room of Unit 1 and locally.
(c) Primary Auxiliary Building Monitor - Channel 6532 Three minimum ventilation areas have been defined for the primary auxiliary building:
(1) Heat exchanger, thermal regeneration demineralizer, and mixed bed demineralizer area, (2) Volume control tank area, and (3) Charging pump area.
These areas, which are potential sources of airborne activity, are maintained at a negative pressure with respect to surrounding areas. The PAB ventilation system collects-potentially contaminated air through a duct system and discharges it to the plant vent via filter train F-16.
The sample withdrawal point for this monitor desp4 (RM-65_32) isgup:ter-of filter train F-16.
The location of this sample withdrawal point provides an early warning to the operating personnel in the event that radioactive material becomes airborne in the PAB.
Indicatior, and alarm is available locally and in the main control room. An alarm indication on these monitors would trigger a radiological evaluation witt..a the areas 45 i
48 12.3-20
SBN-1043 ATTACHMENT 2 DISCUSSION ON PRESENT CONFIGURATION OF PAB RADIATION MONITOR BACKGROUND FSAR Section 12.3.4.2 states that monitored points within the station ventilation system are in areas where potential personnel exposure to radiation is most likely and in several ventilation exhaust ducts.
The Primary Auxiliary Building (PAB) ventilation system is monitored as follows:
RM No.
Description Type Range 6532-1 Air Particulate Skid-Mounted 10 10-7 uci/cm3 6532-2 Radiogas Skid-Mounted 10 10-3 uCi/cm3 6567 Miscellaneous Ventilation Duct-Mounted 101 - 106 cpm 6568 Containment Enclosure Duct-Mounted 101 - 106 cpm Monitor 6567 is located at the inlet to the PAB cleanup filter. The following areas are monitored by this detector:
valve aisle, volume control tank area, sample heat exchanger room, sample room fume hood, degassifier area, PAB lower level Elevation -6 ft., and PAB filter and heat exchanger area.
Monitor 6568 is located in the exhaust duct from the containment enclosure at the inlet to the cleanup filter. The following areas are monitored by this detector:
charging pump cubicles, safety injection pump cubicles, residual heat removal equipment areas, containment spray pump and heat exchanger equipment areas, mechanical penetration area, and the containment enclosure ventilation equipment area.
Monitors 6567 and 6568 are gross activity monitors located in the ducts upstream of the PAB ventilation filters. Monitors 6532-1 and -2 on the other hand are skid-mounted. They utilize isokinetic nozzles and sample lines to draw a sample from the downstream side of the PAB filters. The total exhaust.
f f
l--
flow from the PAB ventilation system is 41,500 cfm. Attachment 3 is a detailed list of the areas and rooms that discharge via the PAB ventilation filters to the plant vent stack.
The PAB ventilation filter housing is a box approximately 18 ft. x 15 ft. x 15 ft.
The PAB ventilation ducts enter this housing approximately 2-1/2 f t. away from the prefilters.
FSAR Section 12.2.2.2 (Leakage Sources - Auxiliary Building) notes that there are several areas in the PAB which have a concentration of piping and valves with a potential for significant contributions to airborne contamination. None of these areas require continuous occupancy. The design basis maximum leakage rate to the PAB, per NUREG-0017, is 20 spd. The source for these areas is reactor coolant with 0.25% fuel clad defects, as presented in Table 11.T-1+.
Airborne concentrations are presented in Table 12.2-35 (Attachment 4 to this letter) for the average contaminated area. shows the expected airborne noble gas and iodino concentrations with 0.25% fuel clad defects. Note that particulates are not expected. Iodines are expected to be accompanied by noble gases.
Section 12.3.4.2, Page 12-7, of the Seabrook Safety Evaluation Report (SER) states:
"The applicant will also provide upstream monitoring for the PAB" (emphasis cdded).
Furthermore, FSAR Section 12.3.4.2.a (Airborne Radioactivity Monitoring Instrumentation) states:
"The sensitivity of the airborne radioactivity monitors is such that they should be capable of detecting ten (10) MPC hours
.of particulate, iodine, and gaseous radioactivity in those plant areas which have contained sources of airborne radioactivity and which may be occupied by personnel....".
DISCUSSION As noted in our telephone conversation with your Mr. Serbu on April 15, 1986, we have determined that the isokinetic nozzles for the PAB ventilation monitor (RM-6532-1, RM-6532-2) have been installed downstream of the PAB ventilation filters rather than upstream as previously required in the SER.
We would like to state our reasons for proposing that the nozzles remain in their installed (downstream) location.
During operation with defective fuel, it is expected that noble gases and iodine predominantly will be present in the PAB ventilation.
Iodine is not likely to be present without noble gases. With respect to monitoring for noble gases, RM-6532-2 will function whether the sample line inlet is upstream or downstream of the PAB filters. Noble gases will penetrate the prefilters, HEPA filters, and charcoal adsorbers. Noble gases are usually tl.) first indication of a breach or leak in a Reactor Coolant System in the PAB.
In addition, Monitor RM-6567 and 6568 would also provide indication of a gross increase in activity in their respective ducts. Radiation protection personnel would be alerted to the need for sampling of the PAB to identify the source of contamination.
Sampling is accomplished using approved procedures for noble gases, particulates, and lodines.
Samples are analyzed in the counting laboratory.
In addition, the station utilizes portable Continuous Air Monitors (CAMS) which aid in pinpointing the affected plant area. Normally one CAM is dedicated for use in the PAB.
Note that RM-6532 does not have radiolodine monitoring capability.
This limitation is imposed by the state-of-the-art in radiation monitors.
A sample is collected for laboratory analysis. There is no monitor alarm.
Detection of in-plant iodine is, therefore, dependent upon an effective plant air sampling program.
3
With c aspect tu nanitor ing for noble gases and iodines, the location of the sample nozzles upstream oc downstream of the PAB filters is irrelevant.
The HEPA filters remove 99.97% of 0.3 micron particles. Therefore, the downnt. ream location of the nozzles will render the particulate channel useful for cnly gross releases of particulates from the PAB.
An indication of 10~
uCi/cm, the minimum sensitivity of the monitor, would mean the testream concentration is on the order of 3 x 10~
uCi/cm or that the filters have been breached.
As stated earlier, particulates are not expected in the PAB ventilation system. Furthermore, a concentration of 3 x 10~
uci/cm in a ventilation line carrying 41,500 cfm would be indicative of a gross failure and is not credible during routine operations.
Particulates are sampled routinely during operation as are noble gases and iodines. Mobile CAMS are also used to monitor particulate concentrations.
Activities which have a high potent ial for gent'ating particulates (e.g., grinding, welding on contamir.ated cystems) will be controlled by a radiation work permit system. Procedures require air sampling, use of respirators, and portable ventilation units during such work as warranted by the degree of hazard.
SUMMARY
We believe the isokinetic nozzles for RM-6532-1 and RM-6532-2 can remain downstream of the PAB ventilation filters for the following reasons:
1.
Monitors RM-6567 and RM-6568, located upstream of the filters, provide indication of gross activity in the ventilation system.
2.
Monitor RM-6532-2 (PAB radiogas) will continue to provide indication of a release of noble gas to the ventilation system in the present downstream location.
3.
There are.a minimum of 25 cubicles or other vent lines that are inputs to the PAB ventilation system.
4.
Item 3, in conjunction with the 41,500 cfm PAB ventilation flow rate, makes it unlikely that a single monitor located upstream or downstream of the PAB filters will detect 10 MPC-hours. This is due to dilution of the room or cubicle ventilation flow in the larger flow of the PAB ventilation system.
5.
Monitoring upstream of the PAB filters in accordance with ANSI Standards is not practical-since the other ventilation lines enter the housing only about 2-1/2 ft. away from the prefilters. An adequate mixing zone prior to the sample nozzles cannot be provided.
6.
A detailed, proceduralized program for monitoring, sampling, and analyzing air samples exists. Portable CAMS and air samplers are used to monitor and sample the PAB atmosphere. Results are trended during normal operation and periods of shutdown to ensure adequate base line data is collected. This data will enable Radiation Protection personnel to take appropriate action when abnormal conditions are encountered. -
y j
SBN-1043 ATTACHMENT 3 Areas and cubicles that discharge to the PAB filters:
,q r r' Charging Pump Rooms (3)
Valve Aisle re V
'f' Pipe Chase (Elevation 53'-0")
,f /
CVCT j,v I
Hot Sample Room (2)
/.
Fume-Hood Seal Water Heat Exchanger Moderating Heat Exchanger Letdown Chiller Letdown Heat Exchanger (2)
Degassifier Area Seal Water Return Filter Seal Water Injection Filter (2)
[
Reactor Coolant Filter Prefilter Fuel Pool Post-Filter F
Fuel Pool Prefilter Aerated Vent Header Hydrogenated Ven'c Header
~
Condenser Mechanical Vacuum Pumps s.
J w
P f
e d
, L.
(
u ATTACMfENT 4 SBN-1043 SB 1 & 2 FSAR TABLE 12.2-35 PRIMARY AUXILIARY BUILDING AIRBORNE ISOTOPIC CONCENTRATIONS 1.45 x 105 ft3 Volume
=
Ventilation Rate 41,500 cfm
=
Specific Activity Isotope (gCi/cc)
MPC Fraction Kr-85m 2.61 - 08*
4.35 - 03 Kr-85 2.03 - 09 2.03 - 04 Kr-87 1.92 - 08 1.92 - 02 Kr-88 5.12 - 08 5.12 - 02 Xe-131m 1.04 - 09 5.22 - 05 Xe-133m 8.60 - 09 8.59 - 04 Xe-133 3.87 - 07 3.87 - 02
(
Xe-135m 1.24 - 08 1.24 - 02 Xe-135 4.80 - 08 1.20 - 02 Xe-138 8.89 - 09 8.89 - 03 I-131 2.90 - 10 3.23 - 02 I-132 1.03 - 10 5.17 - 04 I-133 4.60 - 11 1.53 - 03 I-134 6.48 - 11 1.30 - 04 I-135 2.51 - 10 2.51 - 03 4
TOTAL 5.65 - 07 1.85 - 01
- 2. 61 - 08 = 2. 61 x' 10-8 L.,
.. -. -.